/**
 * Content Processing Service
 * Implements the content processing pipeline as described in the specs
 * Uses Blake hashing for content integrity and encryption key generation
 */

import { cryptoService } from './crypto.service';
import { ipfsService } from './ipfs.service';

/**
 * Interface for processed content metadata
 */
interface ProcessedContentMetadata {
    originalFilename: string;
    normalizedFilename: string;
    blakeHash: string;
    ipfsCid: string;
    combinedKey: string;
    contentType: string;
    size: number;
    timestamp: number;
}

/**
 * Service for processing content files
 * Implements the content processing pipeline:
 * 1. File discovery
 * 2. Filename normalization
 * 3. Original content hashing (Blake)
 * 4. Content encryption
 * 5. Encrypted content upload to IPFS
 */
class ContentProcessorService {
    /**
     * Process a file through the content processing pipeline
     * @param file - File to process
     * @returns Promise<ProcessedContentMetadata> - Metadata of the processed content
     */
    async processFile(file: File): Promise<ProcessedContentMetadata> {
        try {
            // Step 1: Get file information
            const originalFilename = file.name;
            
            // Step 2: Normalize filename (lowercase and snake_case)
            const normalizedFilename = this.normalizeFilename(originalFilename);
            
            // Step 3: Hash the original content using Blake3
            const blakeHash = await cryptoService.hashFileBlake3AsHex(file);
            
            // Step 4: Encrypt the content using the Blake hash as the key
            // Note: This is a placeholder for actual encryption implementation
            const encryptedContent = await this.encryptContent(file, blakeHash);
            
            // Step 5: Upload the encrypted content to IPFS
            const ipfsCid = await ipfsService.uploadContent(encryptedContent);
            
            // Create the combined key (Blake hash + IPFS CID)
            const combinedKey = cryptoService.combineBlakeHashAndIpfsCid(blakeHash, ipfsCid);
            
            // Return the metadata
            return {
                originalFilename,
                normalizedFilename,
                blakeHash,
                ipfsCid,
                combinedKey,
                contentType: file.type,
                size: file.size,
                timestamp: Date.now()
            };
        } catch (error) {
            console.error('Error processing file:', error);
            throw error;
        }
    }
    
    /**
     * Normalize a filename to lowercase and snake_case
     * @param filename - Original filename
     * @returns Normalized filename
     */
    normalizeFilename(filename: string): string {
        // Remove file extension
        const parts = filename.split('.');
        const extension = parts.pop() || '';
        let name = parts.join('.');
        
        // Convert to lowercase
        name = name.toLowerCase();
        
        // Replace spaces and special characters with underscores
        name = name.replace(/[^a-z0-9]/g, '_');
        
        // Replace multiple underscores with a single one
        name = name.replace(/_+/g, '_');
        
        // Remove leading and trailing underscores
        name = name.replace(/^_+|_+$/g, '');
        
        // Add extension back if it exists
        if (extension) {
            name = `${name}.${extension.toLowerCase()}`;
        }
        
        return name;
    }
    
    /**
     * Encrypt content using the Blake hash as the key
     * This is a placeholder for actual encryption implementation
     * @param file - File to encrypt
     * @param key - Encryption key (Blake hash)
     * @returns Promise<string> - Encrypted content as string
     */
    async encryptContent(file: File, key: string): Promise<string> {
        // TODO: Implement actual encryption
        // For now, we'll just return a mock encrypted content
        // This should be replaced with actual encryption using the Blake hash as the key
        
        // Convert the file to a string
        const arrayBuffer = await file.arrayBuffer();
        const contentBytes = new Uint8Array(arrayBuffer);
        
        // Mock encryption by XORing with the key bytes
        // This is NOT secure and is only for demonstration purposes
        const keyBytes = cryptoService.hexToBytes(key);
        const encryptedBytes = new Uint8Array(contentBytes.length);
        
        for (let i = 0; i < contentBytes.length; i++) {
            encryptedBytes[i] = contentBytes[i] ^ keyBytes[i % keyBytes.length];
        }
        
        // Convert to base64 for storage
        return btoa(String.fromCharCode.apply(null, Array.from(encryptedBytes)));
    }
    
    /**
     * Decrypt content using the Blake hash as the key
     * This is a placeholder for actual decryption implementation
     * @param encryptedContent - Encrypted content as string
     * @param key - Decryption key (Blake hash)
     * @returns Promise<Uint8Array> - Decrypted content as Uint8Array
     */
    async decryptContent(encryptedContent: string, key: string): Promise<Uint8Array> {
        // TODO: Implement actual decryption
        // For now, we'll just return a mock decrypted content
        // This should be replaced with actual decryption using the Blake hash as the key
        
        // Convert the base64 string to bytes
        const encryptedBytes = new Uint8Array(
            atob(encryptedContent).split('').map(c => c.charCodeAt(0))
        );
        
        // Mock decryption by XORing with the key bytes
        // This is NOT secure and is only for demonstration purposes
        const keyBytes = cryptoService.hexToBytes(key);
        const decryptedBytes = new Uint8Array(encryptedBytes.length);
        
        for (let i = 0; i < encryptedBytes.length; i++) {
            decryptedBytes[i] = encryptedBytes[i] ^ keyBytes[i % keyBytes.length];
        }
        
        return decryptedBytes;
    }
}

// Create a singleton instance
export const contentProcessorService = new ContentProcessorService();