/**
 *  Chahuadev Framework - Error Handler Module
 * Error Detection, Logging & Debugging Support
 * 
 *  Chahua Development Thailand
 *  CEO: Saharath C.
 *  www.chahuadev.com
 */

const fs = require('fs');
const path = require('path');

class ErrorHandler {
    constructor() {
        this.errorTypes = {
            VALIDATION: 'validation',
            SECURITY: 'security',
            EXECUTION: 'execution',
            SYSTEM: 'system',
            NETWORK: 'network',
            BRIDGE: 'bridge',
            CONTEXT: 'context'
        };

        this.logFile = path.join(process.cwd(), 'logs', 'errors.log');
        this.debugMode = process.env.DEBUG === 'true' || process.env.NODE_ENV === 'development';
        
        this.ensureLogDirectory();
        console.log(' Error Handler initialized');
    }

    /**
     * Handle and log error
     * @param {Error|string} error - Error object or message
     * @param {string} type - Error type
     * @param {Object} context - Pipeline context
     * @param {Object} metadata - Additional metadata
     * @returns {Object} Processed error info
     */
    handle(error, type = this.errorTypes.SYSTEM, context = null, metadata = {}) {
        const errorInfo = this.processError(error, type, context, metadata);
        
        // Log error
        this.log(errorInfo);
        
        // Console output based on debug mode
        if (this.debugMode) {
            this.debugOutput(errorInfo);
        } else {
            console.error(` ${errorInfo.type}: ${errorInfo.message}`);
        }

        return errorInfo;
    }

    /**
     * Process error into standardized format
     * @private
     * @param {Error|string} error - Error object or message
     * @param {string} type - Error type
     * @param {Object} context - Pipeline context
     * @param {Object} metadata - Additional metadata
     * @returns {Object} Processed error info
     */
    processError(error, type, context, metadata) {
        const timestamp = new Date().toISOString();
        const errorId = this.generateErrorId();

        let errorInfo = {
            id: errorId,
            timestamp: timestamp,
            type: type,
            message: '',
            stack: null,
            code: null,
            details: {},
            context: null,
            metadata: metadata || {}
        };

        // Extract error information
        if (error instanceof Error) {
            errorInfo.message = error.message;
            errorInfo.stack = error.stack;
            errorInfo.code = error.code || null;
            
            // Extract additional error properties
            if (error.errno) errorInfo.details.errno = error.errno;
            if (error.syscall) errorInfo.details.syscall = error.syscall;
            if (error.path) errorInfo.details.path = error.path;
        } else {
            errorInfo.message = String(error);
        }

        // Add context information
        if (context) {
            errorInfo.context = {
                pipelineId: context.pipelineId,
                pipelineType: context.pipelineType,
                currentStep: context.steps.length > 0 ? 
                    context.steps[context.steps.length - 1].stepName : 'unknown',
                executionStatus: context.execution.status,
                systemType: context.systemInfo.detectedType
            };
        }

        // Add environment information
        errorInfo.environment = {
            nodeVersion: process.version,
            platform: process.platform,
            arch: process.arch,
            memory: process.memoryUsage(),
            uptime: process.uptime()
        };

        return errorInfo;
    }

    /**
     * Log error to file
     * @private
     * @param {Object} errorInfo - Processed error information
     */
    log(errorInfo) {
        try {
            const logEntry = JSON.stringify(errorInfo) + '\n';
            fs.appendFileSync(this.logFile, logEntry, 'utf8');
        } catch (logError) {
            console.error('Failed to write error log:', logError.message);
        }
    }

    /**
     * Debug output to console
     * @private
     * @param {Object} errorInfo - Processed error information
     */
    debugOutput(errorInfo) {
        console.error('\n=== CHAHUADEV ERROR DEBUG ===');
        console.error(` Error ID: ${errorInfo.id}`);
        console.error(` Timestamp: ${errorInfo.timestamp}`);
        console.error(`  Type: ${errorInfo.type}`);
        console.error(` Message: ${errorInfo.message}`);
        
        if (errorInfo.context) {
            console.error(` Pipeline: ${errorInfo.context.pipelineId}`);
            console.error(` Step: ${errorInfo.context.currentStep}`);
        }
        
        if (errorInfo.stack && this.debugMode) {
            console.error(` Stack Trace:\n${errorInfo.stack}`);
        }
        
        if (Object.keys(errorInfo.details).length > 0) {
            console.error(' Details:', errorInfo.details);
        }
        
        console.error('========================\n');
    }

    /**
     * Create validation error
     * @param {string} message - Error message
     * @param {Object} context - Pipeline context
     * @param {Object} validationData - Validation specific data
     * @returns {Object} Error info
     */
    validation(message, context = null, validationData = {}) {
        return this.handle(
            new Error(message), 
            this.errorTypes.VALIDATION, 
            context, 
            { validationData }
        );
    }

    /**
     * Create security error
     * @param {string} message - Error message
     * @param {Object} context - Pipeline context
     * @param {Object} securityData - Security specific data
     * @returns {Object} Error info
     */
    security(message, context = null, securityData = {}) {
        return this.handle(
            new Error(message), 
            this.errorTypes.SECURITY, 
            context, 
            { securityData }
        );
    }

    /**
     * Create execution error
     * @param {string} message - Error message
     * @param {Object} context - Pipeline context
     * @param {Object} executionData - Execution specific data
     * @returns {Object} Error info
     */
    execution(message, context = null, executionData = {}) {
        return this.handle(
            new Error(message), 
            this.errorTypes.EXECUTION, 
            context, 
            { executionData }
        );
    }

    /**
     * Create bridge communication error
     * @param {string} message - Error message
     * @param {Object} context - Pipeline context
     * @param {Object} bridgeData - Bridge specific data
     * @returns {Object} Error info
     */
    bridge(message, context = null, bridgeData = {}) {
        return this.handle(
            new Error(message), 
            this.errorTypes.BRIDGE, 
            context, 
            { bridgeData }
        );
    }

    /**
     * Create context error
     * @param {string} message - Error message
     * @param {Object} context - Pipeline context
     * @param {Object} contextData - Context specific data
     * @returns {Object} Error info
     */
    context(message, context = null, contextData = {}) {
        return this.handle(
            new Error(message), 
            this.errorTypes.CONTEXT, 
            context, 
            { contextData }
        );
    }

    /**
     * Wrap function with error handling
     * @param {Function} fn - Function to wrap
     * @param {string} errorType - Error type for this function
     * @param {Object} context - Pipeline context
     * @returns {Function} Wrapped function
     */
    wrap(fn, errorType = this.errorTypes.SYSTEM, context = null) {
        return async (...args) => {
            try {
                return await fn(...args);
            } catch (error) {
                this.handle(error, errorType, context, { 
                    functionName: fn.name,
                    arguments: args.length 
                });
                throw error; // Re-throw for upstream handling
            }
        };
    }

    /**
     * Get recent errors
     * @param {number} limit - Number of recent errors to get
     * @param {string} type - Filter by error type
     * @returns {Array} Array of error objects
     */
    getRecentErrors(limit = 10, type = null) {
        try {
            if (!fs.existsSync(this.logFile)) {
                return [];
            }

            const logContent = fs.readFileSync(this.logFile, 'utf8');
            const lines = logContent.trim().split('\n').filter(line => line);
            
            let errors = lines.map(line => {
                try {
                    return JSON.parse(line);
                } catch (e) {
                    return null;
                }
            }).filter(error => error !== null);

            // Filter by type if specified
            if (type) {
                errors = errors.filter(error => error.type === type);
            }

            // Sort by timestamp (newest first) and limit
            return errors
                .sort((a, b) => new Date(b.timestamp) - new Date(a.timestamp))
                .slice(0, limit);
                
        } catch (error) {
            console.error('Failed to read error log:', error.message);
            return [];
        }
    }

    /**
     * Clear error logs
     * @returns {boolean} Success status
     */
    clearLogs() {
        try {
            if (fs.existsSync(this.logFile)) {
                fs.writeFileSync(this.logFile, '', 'utf8');
                console.log(' Error logs cleared');
                return true;
            }
            return true;
        } catch (error) {
            console.error('Failed to clear error logs:', error.message);
            return false;
        }
    }

    /**
     * Generate unique error ID
     * @private
     * @returns {string} Error ID
     */
    generateErrorId() {
        const timestamp = Date.now();
        const random = Math.random().toString(36).substring(2, 8);
        return `err_${timestamp}_${random}`;
    }

    /**
     * Ensure log directory exists
     * @private
     */
    ensureLogDirectory() {
        const logDir = path.dirname(this.logFile);
        if (!fs.existsSync(logDir)) {
            try {
                fs.mkdirSync(logDir, { recursive: true });
            } catch (error) {
                console.warn('Could not create log directory:', error.message);
            }
        }
    }

    /**
     * Get error handler status
     * @returns {Object} Status information
     */
    getStatus() {
        return {
            errorTypes: Object.values(this.errorTypes),
            logFile: this.logFile,
            debugMode: this.debugMode,
            logExists: fs.existsSync(this.logFile),
            ready: true
        };
    }

    /**
     * Set debug mode
     * @param {boolean} enabled - Enable debug mode
     */
    setDebugMode(enabled) {
        this.debugMode = enabled;
        console.log(` Debug mode: ${enabled ? 'enabled' : 'disabled'}`);
    }

    /**
     * Log error with type and metadata (for BaseStrategy compatibility)
     * @param {string} type - Error type
     * @param {Error|string} error - Error object or message
     * @param {Object} metadata - Additional metadata
     */
    logError(type, error, metadata = {}) {
        this.handle(error, type, null, metadata);
    }
}

// Export class (not singleton)
module.exports = ErrorHandler;