...

herodb/src/db/model_methods.rs

@@ -1,7 +1,7 @@
 use crate::db::db::DB;
 use crate::db::base::{SledDBResult, SledModel};
 use crate::impl_model_methods;
-use crate::models::biz::{Product, Sale, Currency, ExchangeRate};
+use crate::models::biz::{Product, Sale, Currency, ExchangeRate, Service, Customer, Contract, Invoice};
 
 // Implement model-specific methods for Product
 impl_model_methods!(Product, product, products);
@@ -13,4 +13,16 @@ impl_model_methods!(Sale, sale, sales);
 impl_model_methods!(Currency, currency, currencies);
 
 // Implement model-specific methods for ExchangeRate
-impl_model_methods!(ExchangeRate, exchange_rate, exchange_rates);
+impl_model_methods!(ExchangeRate, exchange_rate, exchange_rates);
+
+// Implement model-specific methods for Service
+impl_model_methods!(Service, service, services);
+
+// Implement model-specific methods for Customer
+impl_model_methods!(Customer, customer, customers);
+
+// Implement model-specific methods for Contract
+impl_model_methods!(Contract, contract, contracts);
+
+// Implement model-specific methods for Invoice
+impl_model_methods!(Invoice, invoice, invoices);

herodb/src/models/biz/business_models_plan.md

@@ -0,0 +1,371 @@
+# Business Models Implementation Plan
+
+## Overview
+
+This document outlines the plan for implementing new business models in the codebase:
+
+1. **Service**: For tracking recurring payments (similar to Sale)
+2. **Customer**: For storing customer information
+3. **Contract**: For linking services or sales to customers
+4. **Invoice**: For invoicing customers
+
+## Model Diagrams
+
+### Core Models and Relationships
+
+```mermaid
+classDiagram
+    class Service {
+        +id: u32
+        +customer_id: u32
+        +total_amount: Currency
+        +status: ServiceStatus
+        +billing_frequency: BillingFrequency
+        +service_date: DateTime~Utc~
+        +created_at: DateTime~Utc~
+        +updated_at: DateTime~Utc~
+        +items: Vec~ServiceItem~
+        +calculate_total()
+    }
+    
+    class ServiceItem {
+        +id: u32
+        +service_id: u32
+        +name: String
+        +quantity: i32
+        +unit_price: Currency
+        +subtotal: Currency
+        +tax_rate: f64
+        +tax_amount: Currency
+        +is_taxable: bool
+        +active_till: DateTime~Utc~
+    }
+    
+    class Customer {
+        +id: u32
+        +name: String
+        +description: String
+        +pubkey: String
+        +contact_ids: Vec~u32~
+        +created_at: DateTime~Utc~
+        +updated_at: DateTime~Utc~
+    }
+    
+    class Contract {
+        +id: u32
+        +customer_id: u32
+        +service_id: Option~u32~
+        +sale_id: Option~u32~
+        +terms: String
+        +start_date: DateTime~Utc~
+        +end_date: DateTime~Utc~
+        +auto_renewal: bool
+        +renewal_terms: String
+        +status: ContractStatus
+        +created_at: DateTime~Utc~
+        +updated_at: DateTime~Utc~
+    }
+    
+    class Invoice {
+        +id: u32
+        +customer_id: u32
+        +total_amount: Currency
+        +balance_due: Currency
+        +status: InvoiceStatus
+        +payment_status: PaymentStatus
+        +issue_date: DateTime~Utc~
+        +due_date: DateTime~Utc~
+        +created_at: DateTime~Utc~
+        +updated_at: DateTime~Utc~
+        +items: Vec~InvoiceItem~
+        +payments: Vec~Payment~
+    }
+    
+    class InvoiceItem {
+        +id: u32
+        +invoice_id: u32
+        +description: String
+        +amount: Currency
+        +service_id: Option~u32~
+        +sale_id: Option~u32~
+    }
+    
+    class Payment {
+        +amount: Currency
+        +date: DateTime~Utc~
+        +method: String
+    }
+    
+    Service "1" -- "many" ServiceItem : contains
+    Customer "1" -- "many" Service : has
+    Customer "1" -- "many" Contract : has
+    Contract "1" -- "0..1" Service : references
+    Contract "1" -- "0..1" Sale : references
+    Invoice "1" -- "many" InvoiceItem : contains
+    Invoice "1" -- "many" Payment : contains
+    Customer "1" -- "many" Invoice : has
+    InvoiceItem "1" -- "0..1" Service : references
+    InvoiceItem "1" -- "0..1" Sale : references
+```
+
+### Enums and Supporting Types
+
+```mermaid
+classDiagram
+    class BillingFrequency {
+        <<enumeration>>
+        Hourly
+        Daily
+        Weekly
+        Monthly
+        Yearly
+    }
+    
+    class ServiceStatus {
+        <<enumeration>>
+        Active
+        Paused
+        Cancelled
+        Completed
+    }
+    
+    class ContractStatus {
+        <<enumeration>>
+        Active
+        Expired
+        Terminated
+    }
+    
+    class InvoiceStatus {
+        <<enumeration>>
+        Draft
+        Sent
+        Paid
+        Overdue
+        Cancelled
+    }
+    
+    class PaymentStatus {
+        <<enumeration>>
+        Unpaid
+        PartiallyPaid
+        Paid
+    }
+    
+    Service -- ServiceStatus : has
+    Service -- BillingFrequency : has
+    Contract -- ContractStatus : has
+    Invoice -- InvoiceStatus : has
+    Invoice -- PaymentStatus : has
+```
+
+## Detailed Implementation Plan
+
+### 1. Service and ServiceItem (service.rs)
+
+The Service model will be similar to Sale but designed for recurring payments:
+
+- **Service**: Main struct for tracking recurring services
+  - Fields: 
+    - id: u32
+    - customer_id: u32
+    - total_amount: Currency
+    - status: ServiceStatus
+    - billing_frequency: BillingFrequency
+    - service_date: DateTime<Utc>
+    - created_at: DateTime<Utc>
+    - updated_at: DateTime<Utc>
+    - items: Vec<ServiceItem>
+  - Methods: 
+    - calculate_total(): Updates the total_amount based on all items
+    - add_item(item: ServiceItem): Adds an item and updates the total
+    - update_status(status: ServiceStatus): Updates the status and timestamp
+  
+- **ServiceItem**: Items within a service (similar to SaleItem)
+  - Fields: 
+    - id: u32
+    - service_id: u32
+    - name: String
+    - quantity: i32
+    - unit_price: Currency
+    - subtotal: Currency
+    - tax_rate: f64
+    - tax_amount: Currency
+    - is_taxable: bool
+    - active_till: DateTime<Utc>
+  - Methods: 
+    - calculate_subtotal(): Calculates subtotal based on quantity and unit_price
+    - calculate_tax(): Calculates tax amount based on subtotal and tax_rate
+
+- **BillingFrequency**: Enum for different billing periods
+  - Variants: Hourly, Daily, Weekly, Monthly, Yearly
+
+- **ServiceStatus**: Enum for service status
+  - Variants: Active, Paused, Cancelled, Completed
+
+### 2. Customer (customer.rs)
+
+The Customer model will store customer information:
+
+- **Customer**: Main struct for customer data
+  - Fields: 
+    - id: u32
+    - name: String
+    - description: String
+    - pubkey: String
+    - contact_ids: Vec<u32>
+    - created_at: DateTime<Utc>
+    - updated_at: DateTime<Utc>
+  - Methods: 
+    - add_contact(contact_id: u32): Adds a contact ID to the list
+    - remove_contact(contact_id: u32): Removes a contact ID from the list
+
+### 3. Contract (contract.rs)
+
+The Contract model will link services or sales to customers:
+
+- **Contract**: Main struct for contract data
+  - Fields: 
+    - id: u32
+    - customer_id: u32
+    - service_id: Option<u32>
+    - sale_id: Option<u32>
+    - terms: String
+    - start_date: DateTime<Utc>
+    - end_date: DateTime<Utc>
+    - auto_renewal: bool
+    - renewal_terms: String
+    - status: ContractStatus
+    - created_at: DateTime<Utc>
+    - updated_at: DateTime<Utc>
+  - Methods: 
+    - is_active(): bool - Checks if the contract is currently active
+    - is_expired(): bool - Checks if the contract has expired
+    - renew(): Updates the contract dates based on renewal terms
+
+- **ContractStatus**: Enum for contract status
+  - Variants: Active, Expired, Terminated
+
+### 4. Invoice (invoice.rs)
+
+The Invoice model will handle billing:
+
+- **Invoice**: Main struct for invoice data
+  - Fields: 
+    - id: u32
+    - customer_id: u32
+    - total_amount: Currency
+    - balance_due: Currency
+    - status: InvoiceStatus
+    - payment_status: PaymentStatus
+    - issue_date: DateTime<Utc>
+    - due_date: DateTime<Utc>
+    - created_at: DateTime<Utc>
+    - updated_at: DateTime<Utc>
+    - items: Vec<InvoiceItem>
+    - payments: Vec<Payment>
+  - Methods: 
+    - calculate_total(): Updates the total_amount based on all items
+    - add_item(item: InvoiceItem): Adds an item and updates the total
+    - add_payment(payment: Payment): Adds a payment and updates balance_due and payment_status
+    - update_status(status: InvoiceStatus): Updates the status and timestamp
+    - calculate_balance(): Updates the balance_due based on total_amount and payments
+
+- **InvoiceItem**: Items within an invoice
+  - Fields: 
+    - id: u32
+    - invoice_id: u32
+    - description: String
+    - amount: Currency
+    - service_id: Option<u32>
+    - sale_id: Option<u32>
+
+- **Payment**: Struct for tracking payments
+  - Fields:
+    - amount: Currency
+    - date: DateTime<Utc>
+    - method: String
+
+- **InvoiceStatus**: Enum for invoice status
+  - Variants: Draft, Sent, Paid, Overdue, Cancelled
+
+- **PaymentStatus**: Enum for payment status
+  - Variants: Unpaid, PartiallyPaid, Paid
+
+### 5. Updates to mod.rs
+
+We'll need to update the mod.rs file to include the new modules and re-export the types:
+
+```rust
+pub mod currency;
+pub mod product;
+pub mod sale;
+pub mod exchange_rate;
+pub mod service;
+pub mod customer;
+pub mod contract;
+pub mod invoice;
+
+// Re-export all model types for convenience
+pub use product::{Product, ProductComponent, ProductType, ProductStatus};
+pub use sale::{Sale, SaleItem, SaleStatus};
+pub use currency::Currency;
+pub use exchange_rate::{ExchangeRate, ExchangeRateService, EXCHANGE_RATE_SERVICE};
+pub use service::{Service, ServiceItem, ServiceStatus, BillingFrequency};
+pub use customer::Customer;
+pub use contract::{Contract, ContractStatus};
+pub use invoice::{Invoice, InvoiceItem, InvoiceStatus, PaymentStatus, Payment};
+
+// Re-export builder types
+pub use product::{ProductBuilder, ProductComponentBuilder};
+pub use sale::{SaleBuilder, SaleItemBuilder};
+pub use currency::CurrencyBuilder;
+pub use exchange_rate::ExchangeRateBuilder;
+pub use service::{ServiceBuilder, ServiceItemBuilder};
+pub use customer::CustomerBuilder;
+pub use contract::ContractBuilder;
+pub use invoice::{InvoiceBuilder, InvoiceItemBuilder};
+```
+
+### 6. Updates to model_methods.rs
+
+We'll need to update the model_methods.rs file to implement the model methods for the new models:
+
+```rust
+use crate::db::db::DB;
+use crate::db::base::{SledDBResult, SledModel};
+use crate::impl_model_methods;
+use crate::models::biz::{Product, Sale, Currency, ExchangeRate, Service, Customer, Contract, Invoice};
+
+// Implement model-specific methods for Product
+impl_model_methods!(Product, product, products);
+
+// Implement model-specific methods for Sale
+impl_model_methods!(Sale, sale, sales);
+
+// Implement model-specific methods for Currency
+impl_model_methods!(Currency, currency, currencies);
+
+// Implement model-specific methods for ExchangeRate
+impl_model_methods!(ExchangeRate, exchange_rate, exchange_rates);
+
+// Implement model-specific methods for Service
+impl_model_methods!(Service, service, services);
+
+// Implement model-specific methods for Customer
+impl_model_methods!(Customer, customer, customers);
+
+// Implement model-specific methods for Contract
+impl_model_methods!(Contract, contract, contracts);
+
+// Implement model-specific methods for Invoice
+impl_model_methods!(Invoice, invoice, invoices);
+```
+
+## Implementation Approach
+
+1. Create the new model files (service.rs, customer.rs, contract.rs, invoice.rs)
+2. Implement the structs, enums, and methods for each model
+3. Update mod.rs to include the new modules and re-export the types
+4. Update model_methods.rs to implement the model methods for the new models
+5. Test the new models with example code

herodb/src/models/biz/contract.rs

@@ -0,0 +1,250 @@
+use crate::db::base::{SledModel, Storable}; // Import Sled traits from db module
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+
+/// ContractStatus represents the status of a contract
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum ContractStatus {
+    Active,
+    Expired,
+    Terminated,
+}
+
+/// Contract represents a legal agreement between a customer and the business
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Contract {
+    pub id: u32,
+    pub customer_id: u32,
+    pub service_id: Option<u32>,
+    pub sale_id: Option<u32>,
+    pub terms: String,
+    pub start_date: DateTime<Utc>,
+    pub end_date: DateTime<Utc>,
+    pub auto_renewal: bool,
+    pub renewal_terms: String,
+    pub status: ContractStatus,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: DateTime<Utc>,
+}
+
+impl Contract {
+    /// Create a new contract with default timestamps
+    pub fn new(
+        id: u32,
+        customer_id: u32,
+        terms: String,
+        start_date: DateTime<Utc>,
+        end_date: DateTime<Utc>,
+        auto_renewal: bool,
+        renewal_terms: String,
+    ) -> Self {
+        let now = Utc::now();
+        Self {
+            id,
+            customer_id,
+            service_id: None,
+            sale_id: None,
+            terms,
+            start_date,
+            end_date,
+            auto_renewal,
+            renewal_terms,
+            status: ContractStatus::Active,
+            created_at: now,
+            updated_at: now,
+        }
+    }
+    
+    /// Link the contract to a service
+    pub fn link_to_service(&mut self, service_id: u32) {
+        self.service_id = Some(service_id);
+        self.sale_id = None; // A contract can only be linked to either a service or a sale
+        self.updated_at = Utc::now();
+    }
+    
+    /// Link the contract to a sale
+    pub fn link_to_sale(&mut self, sale_id: u32) {
+        self.sale_id = Some(sale_id);
+        self.service_id = None; // A contract can only be linked to either a service or a sale
+        self.updated_at = Utc::now();
+    }
+    
+    /// Check if the contract is currently active
+    pub fn is_active(&self) -> bool {
+        let now = Utc::now();
+        self.status == ContractStatus::Active && 
+            now >= self.start_date && 
+            now <= self.end_date
+    }
+    
+    /// Check if the contract has expired
+    pub fn is_expired(&self) -> bool {
+        let now = Utc::now();
+        now > self.end_date
+    }
+    
+    /// Update the contract status
+    pub fn update_status(&mut self, status: ContractStatus) {
+        self.status = status;
+        self.updated_at = Utc::now();
+    }
+    
+    /// Renew the contract based on renewal terms
+    pub fn renew(&mut self) -> Result<(), &'static str> {
+        if !self.auto_renewal {
+            return Err("Contract is not set for auto-renewal");
+        }
+        
+        if self.status != ContractStatus::Active {
+            return Err("Cannot renew a non-active contract");
+        }
+        
+        // Calculate new dates based on the current end date
+        let duration = self.end_date - self.start_date;
+        self.start_date = self.end_date;
+        self.end_date = self.end_date + duration;
+        
+        self.updated_at = Utc::now();
+        Ok(())
+    }
+}
+
+/// Builder for Contract
+pub struct ContractBuilder {
+    id: Option<u32>,
+    customer_id: Option<u32>,
+    service_id: Option<u32>,
+    sale_id: Option<u32>,
+    terms: Option<String>,
+    start_date: Option<DateTime<Utc>>,
+    end_date: Option<DateTime<Utc>>,
+    auto_renewal: Option<bool>,
+    renewal_terms: Option<String>,
+    status: Option<ContractStatus>,
+    created_at: Option<DateTime<Utc>>,
+    updated_at: Option<DateTime<Utc>>,
+}
+
+impl ContractBuilder {
+    /// Create a new ContractBuilder with all fields set to None
+    pub fn new() -> Self {
+        Self {
+            id: None,
+            customer_id: None,
+            service_id: None,
+            sale_id: None,
+            terms: None,
+            start_date: None,
+            end_date: None,
+            auto_renewal: None,
+            renewal_terms: None,
+            status: None,
+            created_at: None,
+            updated_at: None,
+        }
+    }
+
+    /// Set the id
+    pub fn id(mut self, id: u32) -> Self {
+        self.id = Some(id);
+        self
+    }
+
+    /// Set the customer_id
+    pub fn customer_id(mut self, customer_id: u32) -> Self {
+        self.customer_id = Some(customer_id);
+        self
+    }
+
+    /// Set the service_id
+    pub fn service_id(mut self, service_id: u32) -> Self {
+        self.service_id = Some(service_id);
+        self.sale_id = None; // A contract can only be linked to either a service or a sale
+        self
+    }
+
+    /// Set the sale_id
+    pub fn sale_id(mut self, sale_id: u32) -> Self {
+        self.sale_id = Some(sale_id);
+        self.service_id = None; // A contract can only be linked to either a service or a sale
+        self
+    }
+
+    /// Set the terms
+    pub fn terms<S: Into<String>>(mut self, terms: S) -> Self {
+        self.terms = Some(terms.into());
+        self
+    }
+
+    /// Set the start_date
+    pub fn start_date(mut self, start_date: DateTime<Utc>) -> Self {
+        self.start_date = Some(start_date);
+        self
+    }
+
+    /// Set the end_date
+    pub fn end_date(mut self, end_date: DateTime<Utc>) -> Self {
+        self.end_date = Some(end_date);
+        self
+    }
+
+    /// Set auto_renewal
+    pub fn auto_renewal(mut self, auto_renewal: bool) -> Self {
+        self.auto_renewal = Some(auto_renewal);
+        self
+    }
+
+    /// Set the renewal_terms
+    pub fn renewal_terms<S: Into<String>>(mut self, renewal_terms: S) -> Self {
+        self.renewal_terms = Some(renewal_terms.into());
+        self
+    }
+
+    /// Set the status
+    pub fn status(mut self, status: ContractStatus) -> Self {
+        self.status = Some(status);
+        self
+    }
+
+    /// Build the Contract object
+    pub fn build(self) -> Result<Contract, &'static str> {
+        let now = Utc::now();
+        
+        // Validate that start_date is before end_date
+        let start_date = self.start_date.ok_or("start_date is required")?;
+        let end_date = self.end_date.ok_or("end_date is required")?;
+        
+        if start_date >= end_date {
+            return Err("start_date must be before end_date");
+        }
+        
+        Ok(Contract {
+            id: self.id.ok_or("id is required")?,
+            customer_id: self.customer_id.ok_or("customer_id is required")?,
+            service_id: self.service_id,
+            sale_id: self.sale_id,
+            terms: self.terms.ok_or("terms is required")?,
+            start_date,
+            end_date,
+            auto_renewal: self.auto_renewal.unwrap_or(false),
+            renewal_terms: self.renewal_terms.ok_or("renewal_terms is required")?,
+            status: self.status.unwrap_or(ContractStatus::Active),
+            created_at: self.created_at.unwrap_or(now),
+            updated_at: self.updated_at.unwrap_or(now),
+        })
+    }
+}
+
+// Implement Storable trait (provides default dump/load)
+impl Storable for Contract {}
+
+// Implement SledModel trait
+impl SledModel for Contract {
+    fn get_id(&self) -> String {
+        self.id.to_string()
+    }
+
+    fn db_prefix() -> &'static str {
+        "contract"
+    }
+}

herodb/src/models/biz/customer.rs

@@ -0,0 +1,148 @@
+use crate::db::base::{SledModel, Storable}; // Import Sled traits from db module
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+
+/// Customer represents a customer who can purchase products or services
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Customer {
+    pub id: u32,
+    pub name: String,
+    pub description: String,
+    pub pubkey: String,
+    pub contact_ids: Vec<u32>,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: DateTime<Utc>,
+}
+
+impl Customer {
+    /// Create a new customer with default timestamps
+    pub fn new(
+        id: u32,
+        name: String,
+        description: String,
+        pubkey: String,
+    ) -> Self {
+        let now = Utc::now();
+        Self {
+            id,
+            name,
+            description,
+            pubkey,
+            contact_ids: Vec::new(),
+            created_at: now,
+            updated_at: now,
+        }
+    }
+    
+    /// Add a contact ID to the customer
+    pub fn add_contact(&mut self, contact_id: u32) {
+        if !self.contact_ids.contains(&contact_id) {
+            self.contact_ids.push(contact_id);
+            self.updated_at = Utc::now();
+        }
+    }
+    
+    /// Remove a contact ID from the customer
+    pub fn remove_contact(&mut self, contact_id: u32) -> bool {
+        let len = self.contact_ids.len();
+        self.contact_ids.retain(|&id| id != contact_id);
+        
+        if self.contact_ids.len() < len {
+            self.updated_at = Utc::now();
+            true
+        } else {
+            false
+        }
+    }
+}
+
+/// Builder for Customer
+pub struct CustomerBuilder {
+    id: Option<u32>,
+    name: Option<String>,
+    description: Option<String>,
+    pubkey: Option<String>,
+    contact_ids: Vec<u32>,
+    created_at: Option<DateTime<Utc>>,
+    updated_at: Option<DateTime<Utc>>,
+}
+
+impl CustomerBuilder {
+    /// Create a new CustomerBuilder with all fields set to None
+    pub fn new() -> Self {
+        Self {
+            id: None,
+            name: None,
+            description: None,
+            pubkey: None,
+            contact_ids: Vec::new(),
+            created_at: None,
+            updated_at: None,
+        }
+    }
+
+    /// Set the id
+    pub fn id(mut self, id: u32) -> Self {
+        self.id = Some(id);
+        self
+    }
+
+    /// Set the name
+    pub fn name<S: Into<String>>(mut self, name: S) -> Self {
+        self.name = Some(name.into());
+        self
+    }
+
+    /// Set the description
+    pub fn description<S: Into<String>>(mut self, description: S) -> Self {
+        self.description = Some(description.into());
+        self
+    }
+
+    /// Set the pubkey
+    pub fn pubkey<S: Into<String>>(mut self, pubkey: S) -> Self {
+        self.pubkey = Some(pubkey.into());
+        self
+    }
+
+    /// Add a contact ID
+    pub fn add_contact(mut self, contact_id: u32) -> Self {
+        self.contact_ids.push(contact_id);
+        self
+    }
+
+    /// Set multiple contact IDs
+    pub fn contact_ids(mut self, contact_ids: Vec<u32>) -> Self {
+        self.contact_ids = contact_ids;
+        self
+    }
+
+    /// Build the Customer object
+    pub fn build(self) -> Result<Customer, &'static str> {
+        let now = Utc::now();
+        
+        Ok(Customer {
+            id: self.id.ok_or("id is required")?,
+            name: self.name.ok_or("name is required")?,
+            description: self.description.ok_or("description is required")?,
+            pubkey: self.pubkey.ok_or("pubkey is required")?,
+            contact_ids: self.contact_ids,
+            created_at: self.created_at.unwrap_or(now),
+            updated_at: self.updated_at.unwrap_or(now),
+        })
+    }
+}
+
+// Implement Storable trait (provides default dump/load)
+impl Storable for Customer {}
+
+// Implement SledModel trait
+impl SledModel for Customer {
+    fn get_id(&self) -> String {
+        self.id.to_string()
+    }
+
+    fn db_prefix() -> &'static str {
+        "customer"
+    }
+}

herodb/src/models/biz/invoice.rs

@@ -0,0 +1,507 @@
+use crate::models::biz::Currency; // Use crate:: for importing from the module
+use crate::db::base::{SledModel, Storable}; // Import Sled traits from db module
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+
+/// InvoiceStatus represents the status of an invoice
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum InvoiceStatus {
+    Draft,
+    Sent,
+    Paid,
+    Overdue,
+    Cancelled,
+}
+
+/// PaymentStatus represents the payment status of an invoice
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum PaymentStatus {
+    Unpaid,
+    PartiallyPaid,
+    Paid,
+}
+
+/// Payment represents a payment made against an invoice
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Payment {
+    pub amount: Currency,
+    pub date: DateTime<Utc>,
+    pub method: String,
+}
+
+impl Payment {
+    /// Create a new payment
+    pub fn new(amount: Currency, method: String) -> Self {
+        Self {
+            amount,
+            date: Utc::now(),
+            method,
+        }
+    }
+}
+
+/// InvoiceItem represents an item in an invoice
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct InvoiceItem {
+    pub id: u32,
+    pub invoice_id: u32,
+    pub description: String,
+    pub amount: Currency,
+    pub service_id: Option<u32>,
+    pub sale_id: Option<u32>,
+}
+
+impl InvoiceItem {
+    /// Create a new invoice item
+    pub fn new(
+        id: u32,
+        invoice_id: u32,
+        description: String,
+        amount: Currency,
+    ) -> Self {
+        Self {
+            id,
+            invoice_id,
+            description,
+            amount,
+            service_id: None,
+            sale_id: None,
+        }
+    }
+    
+    /// Link the invoice item to a service
+    pub fn link_to_service(&mut self, service_id: u32) {
+        self.service_id = Some(service_id);
+        self.sale_id = None; // An invoice item can only be linked to either a service or a sale
+    }
+    
+    /// Link the invoice item to a sale
+    pub fn link_to_sale(&mut self, sale_id: u32) {
+        self.sale_id = Some(sale_id);
+        self.service_id = None; // An invoice item can only be linked to either a service or a sale
+    }
+}
+
+/// Builder for InvoiceItem
+pub struct InvoiceItemBuilder {
+    id: Option<u32>,
+    invoice_id: Option<u32>,
+    description: Option<String>,
+    amount: Option<Currency>,
+    service_id: Option<u32>,
+    sale_id: Option<u32>,
+}
+
+impl InvoiceItemBuilder {
+    /// Create a new InvoiceItemBuilder with all fields set to None
+    pub fn new() -> Self {
+        Self {
+            id: None,
+            invoice_id: None,
+            description: None,
+            amount: None,
+            service_id: None,
+            sale_id: None,
+        }
+    }
+
+    /// Set the id
+    pub fn id(mut self, id: u32) -> Self {
+        self.id = Some(id);
+        self
+    }
+
+    /// Set the invoice_id
+    pub fn invoice_id(mut self, invoice_id: u32) -> Self {
+        self.invoice_id = Some(invoice_id);
+        self
+    }
+
+    /// Set the description
+    pub fn description<S: Into<String>>(mut self, description: S) -> Self {
+        self.description = Some(description.into());
+        self
+    }
+
+    /// Set the amount
+    pub fn amount(mut self, amount: Currency) -> Self {
+        self.amount = Some(amount);
+        self
+    }
+
+    /// Set the service_id
+    pub fn service_id(mut self, service_id: u32) -> Self {
+        self.service_id = Some(service_id);
+        self.sale_id = None; // An invoice item can only be linked to either a service or a sale
+        self
+    }
+
+    /// Set the sale_id
+    pub fn sale_id(mut self, sale_id: u32) -> Self {
+        self.sale_id = Some(sale_id);
+        self.service_id = None; // An invoice item can only be linked to either a service or a sale
+        self
+    }
+
+    /// Build the InvoiceItem object
+    pub fn build(self) -> Result<InvoiceItem, &'static str> {
+        Ok(InvoiceItem {
+            id: self.id.ok_or("id is required")?,
+            invoice_id: self.invoice_id.ok_or("invoice_id is required")?,
+            description: self.description.ok_or("description is required")?,
+            amount: self.amount.ok_or("amount is required")?,
+            service_id: self.service_id,
+            sale_id: self.sale_id,
+        })
+    }
+}
+
+/// Invoice represents an invoice sent to a customer
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Invoice {
+    pub id: u32,
+    pub customer_id: u32,
+    pub total_amount: Currency,
+    pub balance_due: Currency,
+    pub status: InvoiceStatus,
+    pub payment_status: PaymentStatus,
+    pub issue_date: DateTime<Utc>,
+    pub due_date: DateTime<Utc>,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: DateTime<Utc>,
+    pub items: Vec<InvoiceItem>,
+    pub payments: Vec<Payment>,
+}
+
+impl Invoice {
+    /// Create a new invoice with default timestamps
+    pub fn new(
+        id: u32,
+        customer_id: u32,
+        currency_code: String,
+        issue_date: DateTime<Utc>,
+        due_date: DateTime<Utc>,
+    ) -> Self {
+        let now = Utc::now();
+        let zero_amount = Currency {
+            amount: 0.0,
+            currency_code: currency_code.clone(),
+        };
+        
+        Self {
+            id,
+            customer_id,
+            total_amount: zero_amount.clone(),
+            balance_due: zero_amount,
+            status: InvoiceStatus::Draft,
+            payment_status: PaymentStatus::Unpaid,
+            issue_date,
+            due_date,
+            created_at: now,
+            updated_at: now,
+            items: Vec::new(),
+            payments: Vec::new(),
+        }
+    }
+    
+    /// Add an item to the invoice and update the total amount
+    pub fn add_item(&mut self, item: InvoiceItem) {
+        // Make sure the item's invoice_id matches this invoice
+        assert_eq!(self.id, item.invoice_id, "Item invoice_id must match invoice id");
+        
+        // Update the total amount
+        if self.items.is_empty() {
+            // First item, initialize the total amount with the same currency
+            self.total_amount = Currency {
+                amount: item.amount.amount,
+                currency_code: item.amount.currency_code.clone(),
+            };
+            self.balance_due = Currency {
+                amount: item.amount.amount,
+                currency_code: item.amount.currency_code.clone(),
+            };
+        } else {
+            // Add to the existing total
+            // (Assumes all items have the same currency)
+            self.total_amount.amount += item.amount.amount;
+            self.balance_due.amount += item.amount.amount;
+        }
+        
+        // Add the item to the list
+        self.items.push(item);
+        
+        // Update the invoice timestamp
+        self.updated_at = Utc::now();
+    }
+    
+    /// Calculate the total amount based on all items
+    pub fn calculate_total(&mut self) {
+        if self.items.is_empty() {
+            return;
+        }
+        
+        // Get the currency code from the first item
+        let currency_code = self.items[0].amount.currency_code.clone();
+        
+        // Calculate the total amount
+        let mut total = 0.0;
+        for item in &self.items {
+            total += item.amount.amount;
+        }
+        
+        // Update the total amount
+        self.total_amount = Currency {
+            amount: total,
+            currency_code: currency_code.clone(),
+        };
+        
+        // Recalculate the balance due
+        self.calculate_balance();
+        
+        // Update the invoice timestamp
+        self.updated_at = Utc::now();
+    }
+    
+    /// Add a payment to the invoice and update the balance due and payment status
+    pub fn add_payment(&mut self, payment: Payment) {
+        // Update the balance due
+        self.balance_due.amount -= payment.amount.amount;
+        
+        // Add the payment to the list
+        self.payments.push(payment);
+        
+        // Update the payment status
+        self.update_payment_status();
+        
+        // Update the invoice timestamp
+        self.updated_at = Utc::now();
+    }
+    
+    /// Calculate the balance due based on total amount and payments
+    pub fn calculate_balance(&mut self) {
+        // Start with the total amount
+        let mut balance = self.total_amount.amount;
+        
+        // Subtract all payments
+        for payment in &self.payments {
+            balance -= payment.amount.amount;
+        }
+        
+        // Update the balance due
+        self.balance_due = Currency {
+            amount: balance,
+            currency_code: self.total_amount.currency_code.clone(),
+        };
+        
+        // Update the payment status
+        self.update_payment_status();
+    }
+    
+    /// Update the payment status based on the balance due
+    fn update_payment_status(&mut self) {
+        if self.balance_due.amount <= 0.0 {
+            self.payment_status = PaymentStatus::Paid;
+            // If fully paid, also update the invoice status
+            if self.status != InvoiceStatus::Cancelled {
+                self.status = InvoiceStatus::Paid;
+            }
+        } else if self.payments.is_empty() {
+            self.payment_status = PaymentStatus::Unpaid;
+        } else {
+            self.payment_status = PaymentStatus::PartiallyPaid;
+        }
+    }
+    
+    /// Update the status of the invoice
+    pub fn update_status(&mut self, status: InvoiceStatus) {
+        self.status = status;
+        self.updated_at = Utc::now();
+        
+        // If the invoice is cancelled, don't change the payment status
+        if status != InvoiceStatus::Cancelled {
+            // Re-evaluate the payment status
+            self.update_payment_status();
+        }
+    }
+    
+    /// Check if the invoice is overdue
+    pub fn is_overdue(&self) -> bool {
+        let now = Utc::now();
+        self.payment_status != PaymentStatus::Paid && 
+            now > self.due_date && 
+            self.status != InvoiceStatus::Cancelled
+    }
+    
+    /// Mark the invoice as overdue if it's past the due date
+    pub fn check_if_overdue(&mut self) -> bool {
+        if self.is_overdue() && self.status != InvoiceStatus::Overdue {
+            self.status = InvoiceStatus::Overdue;
+            self.updated_at = Utc::now();
+            true
+        } else {
+            false
+        }
+    }
+}
+
+/// Builder for Invoice
+pub struct InvoiceBuilder {
+    id: Option<u32>,
+    customer_id: Option<u32>,
+    total_amount: Option<Currency>,
+    balance_due: Option<Currency>,
+    status: Option<InvoiceStatus>,
+    payment_status: Option<PaymentStatus>,
+    issue_date: Option<DateTime<Utc>>,
+    due_date: Option<DateTime<Utc>>,
+    created_at: Option<DateTime<Utc>>,
+    updated_at: Option<DateTime<Utc>>,
+    items: Vec<InvoiceItem>,
+    payments: Vec<Payment>,
+    currency_code: Option<String>,
+}
+
+impl InvoiceBuilder {
+    /// Create a new InvoiceBuilder with all fields set to None
+    pub fn new() -> Self {
+        Self {
+            id: None,
+            customer_id: None,
+            total_amount: None,
+            balance_due: None,
+            status: None,
+            payment_status: None,
+            issue_date: None,
+            due_date: None,
+            created_at: None,
+            updated_at: None,
+            items: Vec::new(),
+            payments: Vec::new(),
+            currency_code: None,
+        }
+    }
+
+    /// Set the id
+    pub fn id(mut self, id: u32) -> Self {
+        self.id = Some(id);
+        self
+    }
+
+    /// Set the customer_id
+    pub fn customer_id(mut self, customer_id: u32) -> Self {
+        self.customer_id = Some(customer_id);
+        self
+    }
+
+    /// Set the currency_code
+    pub fn currency_code<S: Into<String>>(mut self, currency_code: S) -> Self {
+        self.currency_code = Some(currency_code.into());
+        self
+    }
+
+    /// Set the status
+    pub fn status(mut self, status: InvoiceStatus) -> Self {
+        self.status = Some(status);
+        self
+    }
+
+    /// Set the issue_date
+    pub fn issue_date(mut self, issue_date: DateTime<Utc>) -> Self {
+        self.issue_date = Some(issue_date);
+        self
+    }
+
+    /// Set the due_date
+    pub fn due_date(mut self, due_date: DateTime<Utc>) -> Self {
+        self.due_date = Some(due_date);
+        self
+    }
+
+    /// Add an item to the invoice
+    pub fn add_item(mut self, item: InvoiceItem) -> Self {
+        self.items.push(item);
+        self
+    }
+
+    /// Add a payment to the invoice
+    pub fn add_payment(mut self, payment: Payment) -> Self {
+        self.payments.push(payment);
+        self
+    }
+
+    /// Build the Invoice object
+    pub fn build(self) -> Result<Invoice, &'static str> {
+        let now = Utc::now();
+        let id = self.id.ok_or("id is required")?;
+        let currency_code = self.currency_code.ok_or("currency_code is required")?;
+        
+        // Initialize with empty total amount and balance due
+        let mut total_amount = Currency {
+            amount: 0.0,
+            currency_code: currency_code.clone(),
+        };
+        
+        // Calculate total amount from items
+        for item in &self.items {
+            // Make sure the item's invoice_id matches this invoice
+            if item.invoice_id != id {
+                return Err("Item invoice_id must match invoice id");
+            }
+            
+            total_amount.amount += item.amount.amount;
+        }
+        
+        // Calculate balance due (total minus payments)
+        let mut balance_due = total_amount.clone();
+        for payment in &self.payments {
+            balance_due.amount -= payment.amount.amount;
+        }
+        
+        // Determine payment status
+        let payment_status = if balance_due.amount <= 0.0 {
+            PaymentStatus::Paid
+        } else if self.payments.is_empty() {
+            PaymentStatus::Unpaid
+        } else {
+            PaymentStatus::PartiallyPaid
+        };
+        
+        // Determine invoice status if not provided
+        let status = if let Some(status) = self.status {
+            status
+        } else if payment_status == PaymentStatus::Paid {
+            InvoiceStatus::Paid
+        } else {
+            InvoiceStatus::Draft
+        };
+
+        Ok(Invoice {
+            id,
+            customer_id: self.customer_id.ok_or("customer_id is required")?,
+            total_amount: self.total_amount.unwrap_or(total_amount),
+            balance_due: self.balance_due.unwrap_or(balance_due),
+            status,
+            payment_status,
+            issue_date: self.issue_date.ok_or("issue_date is required")?,
+            due_date: self.due_date.ok_or("due_date is required")?,
+            created_at: self.created_at.unwrap_or(now),
+            updated_at: self.updated_at.unwrap_or(now),
+            items: self.items,
+            payments: self.payments,
+        })
+    }
+}
+
+// Implement Storable trait (provides default dump/load)
+impl Storable for Invoice {}
+
+// Implement SledModel trait
+impl SledModel for Invoice {
+    fn get_id(&self) -> String {
+        self.id.to_string()
+    }
+
+    fn db_prefix() -> &'static str {
+        "invoice"
+    }
+}

herodb/src/models/biz/mod.rs

@@ -2,15 +2,27 @@ pub mod currency;
 pub mod product;
 pub mod sale;
 pub mod exchange_rate;
+pub mod service;
+pub mod customer;
+pub mod contract;
+pub mod invoice;
 
 // Re-export all model types for convenience
 pub use product::{Product, ProductComponent, ProductType, ProductStatus};
 pub use sale::{Sale, SaleItem, SaleStatus};
 pub use currency::Currency;
 pub use exchange_rate::{ExchangeRate, ExchangeRateService, EXCHANGE_RATE_SERVICE};
+pub use service::{Service, ServiceItem, ServiceStatus, BillingFrequency};
+pub use customer::Customer;
+pub use contract::{Contract, ContractStatus};
+pub use invoice::{Invoice, InvoiceItem, InvoiceStatus, PaymentStatus, Payment};
 
 // Re-export builder types
 pub use product::{ProductBuilder, ProductComponentBuilder};
 pub use sale::{SaleBuilder, SaleItemBuilder};
 pub use currency::CurrencyBuilder;
-pub use exchange_rate::ExchangeRateBuilder;
+pub use exchange_rate::ExchangeRateBuilder;
+pub use service::{ServiceBuilder, ServiceItemBuilder};
+pub use customer::CustomerBuilder;
+pub use contract::ContractBuilder;
+pub use invoice::{InvoiceBuilder, InvoiceItemBuilder};

herodb/src/models/biz/service.rs

@@ -0,0 +1,469 @@
+use crate::models::biz::Currency; // Use crate:: for importing from the module
+use crate::db::base::{SledModel, Storable}; // Import Sled traits from db module
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+
+/// BillingFrequency represents the frequency of billing for a service
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum BillingFrequency {
+    Hourly,
+    Daily,
+    Weekly,
+    Monthly,
+    Yearly,
+}
+
+/// ServiceStatus represents the status of a service
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum ServiceStatus {
+    Active,
+    Paused,
+    Cancelled,
+    Completed,
+}
+
+/// ServiceItem represents an item in a service
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ServiceItem {
+    pub id: u32,
+    pub service_id: u32,
+    pub product_id: u32,
+    pub name: String,
+    pub quantity: i32,
+    pub unit_price: Currency,
+    pub subtotal: Currency,
+    pub tax_rate: f64,
+    pub tax_amount: Currency,
+    pub is_taxable: bool,
+    pub active_till: DateTime<Utc>,
+}
+
+impl ServiceItem {
+    /// Create a new service item
+    pub fn new(
+        id: u32,
+        service_id: u32,
+        product_id: u32,
+        name: String,
+        quantity: i32,
+        unit_price: Currency,
+        tax_rate: f64,
+        is_taxable: bool,
+        active_till: DateTime<Utc>,
+    ) -> Self {
+        // Calculate subtotal
+        let amount = unit_price.amount * quantity as f64;
+        let subtotal = Currency {
+            amount,
+            currency_code: unit_price.currency_code.clone(),
+        };
+        
+        // Calculate tax amount if taxable
+        let tax_amount = if is_taxable {
+            Currency {
+                amount: subtotal.amount * tax_rate,
+                currency_code: unit_price.currency_code.clone(),
+            }
+        } else {
+            Currency {
+                amount: 0.0,
+                currency_code: unit_price.currency_code.clone(),
+            }
+        };
+        
+        Self {
+            id,
+            service_id,
+            product_id,
+            name,
+            quantity,
+            unit_price,
+            subtotal,
+            tax_rate,
+            tax_amount,
+            is_taxable,
+            active_till,
+        }
+    }
+    
+    /// Calculate the subtotal based on quantity and unit price
+    pub fn calculate_subtotal(&mut self) {
+        let amount = self.unit_price.amount * self.quantity as f64;
+        self.subtotal = Currency {
+            amount,
+            currency_code: self.unit_price.currency_code.clone(),
+        };
+    }
+    
+    /// Calculate the tax amount based on subtotal and tax rate
+    pub fn calculate_tax(&mut self) {
+        if self.is_taxable {
+            self.tax_amount = Currency {
+                amount: self.subtotal.amount * self.tax_rate,
+                currency_code: self.subtotal.currency_code.clone(),
+            };
+        } else {
+            self.tax_amount = Currency {
+                amount: 0.0,
+                currency_code: self.subtotal.currency_code.clone(),
+            };
+        }
+    }
+}
+
+/// Builder for ServiceItem
+pub struct ServiceItemBuilder {
+    id: Option<u32>,
+    service_id: Option<u32>,
+    product_id: Option<u32>,
+    name: Option<String>,
+    quantity: Option<i32>,
+    unit_price: Option<Currency>,
+    subtotal: Option<Currency>,
+    tax_rate: Option<f64>,
+    tax_amount: Option<Currency>,
+    is_taxable: Option<bool>,
+    active_till: Option<DateTime<Utc>>,
+}
+
+impl ServiceItemBuilder {
+    /// Create a new ServiceItemBuilder with all fields set to None
+    pub fn new() -> Self {
+        Self {
+            id: None,
+            service_id: None,
+            product_id: None,
+            name: None,
+            quantity: None,
+            unit_price: None,
+            subtotal: None,
+            tax_rate: None,
+            tax_amount: None,
+            is_taxable: None,
+            active_till: None,
+        }
+    }
+
+    /// Set the id
+    pub fn id(mut self, id: u32) -> Self {
+        self.id = Some(id);
+        self
+    }
+
+    /// Set the service_id
+    pub fn service_id(mut self, service_id: u32) -> Self {
+        self.service_id = Some(service_id);
+        self
+    }
+
+    /// Set the product_id
+    pub fn product_id(mut self, product_id: u32) -> Self {
+        self.product_id = Some(product_id);
+        self
+    }
+
+    /// Set the name
+    pub fn name<S: Into<String>>(mut self, name: S) -> Self {
+        self.name = Some(name.into());
+        self
+    }
+
+    /// Set the quantity
+    pub fn quantity(mut self, quantity: i32) -> Self {
+        self.quantity = Some(quantity);
+        self
+    }
+
+    /// Set the unit_price
+    pub fn unit_price(mut self, unit_price: Currency) -> Self {
+        self.unit_price = Some(unit_price);
+        self
+    }
+
+    /// Set the tax_rate
+    pub fn tax_rate(mut self, tax_rate: f64) -> Self {
+        self.tax_rate = Some(tax_rate);
+        self
+    }
+
+    /// Set is_taxable
+    pub fn is_taxable(mut self, is_taxable: bool) -> Self {
+        self.is_taxable = Some(is_taxable);
+        self
+    }
+
+    /// Set the active_till
+    pub fn active_till(mut self, active_till: DateTime<Utc>) -> Self {
+        self.active_till = Some(active_till);
+        self
+    }
+
+    /// Build the ServiceItem object
+    pub fn build(self) -> Result<ServiceItem, &'static str> {
+        let unit_price = self.unit_price.ok_or("unit_price is required")?;
+        let quantity = self.quantity.ok_or("quantity is required")?;
+        let tax_rate = self.tax_rate.unwrap_or(0.0);
+        let is_taxable = self.is_taxable.unwrap_or(false);
+        
+        // Calculate subtotal
+        let amount = unit_price.amount * quantity as f64;
+        let subtotal = Currency {
+            amount,
+            currency_code: unit_price.currency_code.clone(),
+        };
+        
+        // Calculate tax amount if taxable
+        let tax_amount = if is_taxable {
+            Currency {
+                amount: subtotal.amount * tax_rate,
+                currency_code: unit_price.currency_code.clone(),
+            }
+        } else {
+            Currency {
+                amount: 0.0,
+                currency_code: unit_price.currency_code.clone(),
+            }
+        };
+
+        Ok(ServiceItem {
+            id: self.id.ok_or("id is required")?,
+            service_id: self.service_id.ok_or("service_id is required")?,
+            product_id: self.product_id.ok_or("product_id is required")?,
+            name: self.name.ok_or("name is required")?,
+            quantity,
+            unit_price,
+            subtotal,
+            tax_rate,
+            tax_amount,
+            is_taxable,
+            active_till: self.active_till.ok_or("active_till is required")?,
+        })
+    }
+}
+
+/// Service represents a recurring service with billing frequency
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Service {
+    pub id: u32,
+    pub customer_id: u32,
+    pub total_amount: Currency,
+    pub status: ServiceStatus,
+    pub billing_frequency: BillingFrequency,
+    pub service_date: DateTime<Utc>,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: DateTime<Utc>,
+    pub items: Vec<ServiceItem>,
+}
+
+impl Service {
+    /// Create a new service with default timestamps
+    pub fn new(
+        id: u32,
+        customer_id: u32,
+        currency_code: String,
+        status: ServiceStatus,
+        billing_frequency: BillingFrequency,
+    ) -> Self {
+        let now = Utc::now();
+        Self {
+            id,
+            customer_id,
+            total_amount: Currency { amount: 0.0, currency_code },
+            status,
+            billing_frequency,
+            service_date: now,
+            created_at: now,
+            updated_at: now,
+            items: Vec::new(),
+        }
+    }
+    
+    /// Add an item to the service and update the total amount
+    pub fn add_item(&mut self, item: ServiceItem) {
+        // Make sure the item's service_id matches this service
+        assert_eq!(self.id, item.service_id, "Item service_id must match service id");
+        
+        // Update the total amount
+        if self.items.is_empty() {
+            // First item, initialize the total amount with the same currency
+            self.total_amount = Currency {
+                amount: item.subtotal.amount + item.tax_amount.amount,
+                currency_code: item.subtotal.currency_code.clone(),
+            };
+        } else {
+            // Add to the existing total
+            // (Assumes all items have the same currency)
+            self.total_amount.amount += item.subtotal.amount + item.tax_amount.amount;
+        }
+        
+        // Add the item to the list
+        self.items.push(item);
+        
+        // Update the service timestamp
+        self.updated_at = Utc::now();
+    }
+    
+    /// Calculate the total amount based on all items
+    pub fn calculate_total(&mut self) {
+        if self.items.is_empty() {
+            return;
+        }
+        
+        // Get the currency code from the first item
+        let currency_code = self.items[0].subtotal.currency_code.clone();
+        
+        // Calculate the total amount
+        let mut total = 0.0;
+        for item in &self.items {
+            total += item.subtotal.amount + item.tax_amount.amount;
+        }
+        
+        // Update the total amount
+        self.total_amount = Currency {
+            amount: total,
+            currency_code,
+        };
+        
+        // Update the service timestamp
+        self.updated_at = Utc::now();
+    }
+    
+    /// Update the status of the service
+    pub fn update_status(&mut self, status: ServiceStatus) {
+        self.status = status;
+        self.updated_at = Utc::now();
+    }
+}
+
+/// Builder for Service
+pub struct ServiceBuilder {
+    id: Option<u32>,
+    customer_id: Option<u32>,
+    total_amount: Option<Currency>,
+    status: Option<ServiceStatus>,
+    billing_frequency: Option<BillingFrequency>,
+    service_date: Option<DateTime<Utc>>,
+    created_at: Option<DateTime<Utc>>,
+    updated_at: Option<DateTime<Utc>>,
+    items: Vec<ServiceItem>,
+    currency_code: Option<String>,
+}
+
+impl ServiceBuilder {
+    /// Create a new ServiceBuilder with all fields set to None
+    pub fn new() -> Self {
+        Self {
+            id: None,
+            customer_id: None,
+            total_amount: None,
+            status: None,
+            billing_frequency: None,
+            service_date: None,
+            created_at: None,
+            updated_at: None,
+            items: Vec::new(),
+            currency_code: None,
+        }
+    }
+
+    /// Set the id
+    pub fn id(mut self, id: u32) -> Self {
+        self.id = Some(id);
+        self
+    }
+
+    /// Set the customer_id
+    pub fn customer_id(mut self, customer_id: u32) -> Self {
+        self.customer_id = Some(customer_id);
+        self
+    }
+
+    /// Set the currency_code
+    pub fn currency_code<S: Into<String>>(mut self, currency_code: S) -> Self {
+        self.currency_code = Some(currency_code.into());
+        self
+    }
+
+    /// Set the status
+    pub fn status(mut self, status: ServiceStatus) -> Self {
+        self.status = Some(status);
+        self
+    }
+
+    /// Set the billing_frequency
+    pub fn billing_frequency(mut self, billing_frequency: BillingFrequency) -> Self {
+        self.billing_frequency = Some(billing_frequency);
+        self
+    }
+
+    /// Set the service_date
+    pub fn service_date(mut self, service_date: DateTime<Utc>) -> Self {
+        self.service_date = Some(service_date);
+        self
+    }
+
+    /// Add an item to the service
+    pub fn add_item(mut self, item: ServiceItem) -> Self {
+        self.items.push(item);
+        self
+    }
+
+    /// Build the Service object
+    pub fn build(self) -> Result<Service, &'static str> {
+        let now = Utc::now();
+        let id = self.id.ok_or("id is required")?;
+        let currency_code = self.currency_code.ok_or("currency_code is required")?;
+        
+        // Initialize with empty total amount
+        let mut total_amount = Currency {
+            amount: 0.0,
+            currency_code: currency_code.clone(),
+        };
+        
+        // Calculate total amount from items
+        for item in &self.items {
+            // Make sure the item's service_id matches this service
+            if item.service_id != id {
+                return Err("Item service_id must match service id");
+            }
+            
+            if total_amount.amount == 0.0 {
+                // First item, initialize the total amount with the same currency
+                total_amount = Currency {
+                    amount: item.subtotal.amount + item.tax_amount.amount,
+                    currency_code: item.subtotal.currency_code.clone(),
+                };
+            } else {
+                // Add to the existing total
+                // (Assumes all items have the same currency)
+                total_amount.amount += item.subtotal.amount + item.tax_amount.amount;
+            }
+        }
+
+        Ok(Service {
+            id,
+            customer_id: self.customer_id.ok_or("customer_id is required")?,
+            total_amount: self.total_amount.unwrap_or(total_amount),
+            status: self.status.ok_or("status is required")?,
+            billing_frequency: self.billing_frequency.ok_or("billing_frequency is required")?,
+            service_date: self.service_date.unwrap_or(now),
+            created_at: self.created_at.unwrap_or(now),
+            updated_at: self.updated_at.unwrap_or(now),
+            items: self.items,
+        })
+    }
+}
+
+// Implement Storable trait (provides default dump/load)
+impl Storable for Service {}
+
+// Implement SledModel trait
+impl SledModel for Service {
+    fn get_id(&self) -> String {
+        self.id.to_string()
+    }
+
+    fn db_prefix() -> &'static str {
+        "service"
+    }
+}