rhaj/rhai_wrapper/examples/rust_rhai_wrapper_example.rs

use rhai::Engine;
use rhai_wrapper::rust_rhai_wrapper;
use std::error::Error;
use std::fmt;

// Define a custom error type for Result examples
#[derive(Debug, Clone)]
struct MyError(String);

impl fmt::Display for MyError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl Error for MyError {}

impl From<String> for MyError {
    fn from(s: String) -> Self {
        MyError(s)
    }
}

fn main() {
    // Create a Rhai engine
    let mut engine = Engine::new();
    
    // 1. Basic example: Add two numbers
    // Define the original Rust function
    fn add(a: i32, b: i32) -> i32 {
        a + b
    }
    
    // Register it with Rhai
    engine.register_fn("add_rhai", add);
    
    // Create a wrapper function that calls Rhai which calls the Rust function
    rust_rhai_wrapper!(add_via_rhai, "add_rhai", (i32, i32) -> i32);
    
    // Test the full circle
    let result = add_via_rhai(&mut engine, 5, 3);
    println!("add_via_rhai(5, 3) = {}", result);
    
    // 2. String manipulation example
    fn concat(s1: String, s2: String) -> String {
        format!("{} {}", s1, s2)
    }
    
    engine.register_fn("concat_rhai", concat);
    rust_rhai_wrapper!(concat_via_rhai, "concat_rhai", (String, String) -> String);
    
    let result = concat_via_rhai(&mut engine, "Hello".to_string(), "World".to_string());
    println!("concat_via_rhai(\"Hello\", \"World\") = {}", result);
    
    // 3. Function with no arguments
    fn get_random() -> i32 {
        42 // Not so random, but it's just an example
    }
    
    engine.register_fn("get_random_rhai", get_random);
    rust_rhai_wrapper!(get_random_via_rhai, "get_random_rhai", () -> i32);
    
    let result = get_random_via_rhai(&mut engine);
    println!("get_random_via_rhai() = {}", result);
    
    // 4. Function with more arguments
    fn calculate(a: i32, b: i32, c: i32, d: i32) -> i32 {
        a + b * c - d
    }
    
    engine.register_fn("calculate_rhai", calculate);
    rust_rhai_wrapper!(calculate_via_rhai, "calculate_rhai", (i32, i32, i32, i32) -> i32);
    
    let result = calculate_via_rhai(&mut engine, 5, 3, 2, 1);
    println!("calculate_via_rhai(5, 3, 2, 1) = {}", result);
    
    // 5. Function that handles errors with a custom return type
    fn divide(a: i32, b: i32) -> Result<i32, String> {
        if b == 0 {
            Err("Division by zero".to_string())
        } else {
            Ok(a / b)
        }
    }
    
    // Register a safe division function that returns an array with success flag and result/error
    engine.register_fn("safe_divide", |a: i32, b: i32| -> rhai::Array {
        if b == 0 {
            // Return [false, error message]
            let mut arr = rhai::Array::new();
            arr.push(rhai::Dynamic::from(false));
            arr.push(rhai::Dynamic::from("Division by zero"));
            arr
        } else {
            // Return [true, result]
            let mut arr = rhai::Array::new();
            arr.push(rhai::Dynamic::from(true));
            arr.push(rhai::Dynamic::from(a / b));
            arr
        }
    });
    
    // Create a wrapper for the safe_divide function
    rust_rhai_wrapper!(safe_divide_via_rhai, "safe_divide", (i32, i32) -> rhai::Array);
    
    // Test success case
    let result = safe_divide_via_rhai(&mut engine, 10, 2);
    println!("safe_divide_via_rhai(10, 2) = {:?}", result);
    
    // Test error case
    let result = safe_divide_via_rhai(&mut engine, 10, 0);
    println!("safe_divide_via_rhai(10, 0) = {:?}", result);
    
    // Process the result
    let success = result[0].as_bool().unwrap();
    if success {
        println!("Division result: {}", result[1].as_int().unwrap());
    } else {
        println!("Division error: {}", result[1].clone().into_string().unwrap());
    }
    
    // 6. Complex example: Using a custom type with Rhai
    #[derive(Debug, Clone)]
    struct Person {
        name: String,
        age: i32,
    }
    
    // Register type and methods with Rhai
    engine.register_type::<Person>();
    engine.register_fn("new_person", |name: String, age: i32| -> Person {
        Person { name, age }
    });
    engine.register_fn("get_name", |p: &mut Person| -> String {
        p.name.clone()
    });
    engine.register_fn("get_age", |p: &mut Person| -> i32 {
        p.age
    });
    engine.register_fn("is_adult", |p: &mut Person| -> bool {
        p.age >= 18
    });
    
    // Register a function that creates a person and checks if they're an adult
    engine.register_fn("create_and_check_person", |name: String, age: i32| -> rhai::Array {
        let person = Person { name, age };
        let is_adult = person.age >= 18;
        
        // Create an array with the person and the is_adult flag
        let mut arr = rhai::Array::new();
        
        // Convert the person to a map for Rhai
        let mut map = rhai::Map::new();
        map.insert("name".into(), rhai::Dynamic::from(person.name));
        map.insert("age".into(), rhai::Dynamic::from(person.age));
        
        arr.push(rhai::Dynamic::from(map));
        arr.push(rhai::Dynamic::from(is_adult));
        arr
    });
    
    // Create a wrapper for the Rhai function
    rust_rhai_wrapper!(create_person_via_rhai, "create_and_check_person", (String, i32) -> rhai::Array);
    
    // Test the wrapper
    let result = create_person_via_rhai(&mut engine, "Alice".to_string(), 25);
    println!("create_person_via_rhai(\"Alice\", 25) = {:?}", result);
    
    // Extract data from the Rhai array
    let person_map = result[0].clone().try_cast::<rhai::Map>().expect("Expected a Map");
    let is_adult = result[1].clone().as_bool().expect("Expected a boolean");
    
    println!("Person: {:?}, Is Adult: {}", person_map, is_adult);
    
    println!("All examples completed successfully!");
}