// Conversation memory handler for DubAPI bot
class MemoryHandler {
    constructor(options = {}) {
        // Maximum number of messages to remember per user
        this.maxMessagesPerUser = options.maxMessagesPerUser || 50;
        // Maximum age of messages to keep (in milliseconds)
        this.maxMemoryAge = options.maxMemoryAge || 30 * 60 * 1000; // Default: 30 minutes
        // Memory storage: Map of username -> array of message objects
        this.memories = new Map();
        
        console.log(`Memory handler initialized (max ${this.maxMessagesPerUser} messages per user, ${this.maxMemoryAge/60000} minutes retention)`);
        
        // Set up periodic cleanup
        this.startCleanupInterval();
    }
    
    /**
     * Add a message to a user's conversation history
     * @param {string} username - The username of the person speaking
     * @param {string} message - The message content
     * @param {boolean} isBot - Whether this message was from the bot
     */
    addMessage(username, message, isBot = false) {
        // Normalize username to lowercase for consistent lookups
        const normalizedUsername = username.toLowerCase();
        
        // Get or create user's memory array
        if (!this.memories.has(normalizedUsername)) {
            this.memories.set(normalizedUsername, []);
        }
        
        const userMemory = this.memories.get(normalizedUsername);
        
        // Add new message with timestamp
        userMemory.push({
            timestamp: Date.now(),
            message: message,
            isBot: isBot
        });
        
        // Trim to max size if needed
        if (userMemory.length > this.maxMessagesPerUser) {
            userMemory.shift(); // Remove oldest message
        }
    }
    
    /**
     * Get conversation history for a user
     * @param {string} username - The username to get history for
     * @param {number} limit - Maximum number of messages to retrieve (defaults to all)
     * @returns {Array} - Array of conversation messages
     */
    getConversationHistory(username, limit = null) {
        const normalizedUsername = username.toLowerCase();
        
        if (!this.memories.has(normalizedUsername)) {
            return [];
        }
        
        const userMemory = this.memories.get(normalizedUsername);
        const result = limit ? userMemory.slice(-limit) : userMemory;
        
        return result;
    }
    
    /**
     * Format conversation history for use in AI prompt
     * @param {string} username - The username to get history for
     * @param {number} limit - Maximum number of messages to include
     * @returns {string} - Formatted conversation history
     */
    getFormattedHistory(username, limit = 5) {
        const history = this.getConversationHistory(username, limit);
        
        if (history.length === 0) {
            return "";
        }
        
        let formatted = "Previous conversation:\n";
        
        history.forEach(item => {
            const speaker = item.isBot ? "Bot" : username;
            formatted += `${speaker}: ${item.message}\n`;
        });
        
        return formatted;
    }
    
    /**
     * Remove old messages from memory that exceed the age limit
     */
    cleanupOldMessages() {
        const now = Date.now();
        const cutoffTime = now - this.maxMemoryAge;
        
        // Check each user's memory
        for (const [username, messages] of this.memories.entries()) {
            // Filter out old messages
            const freshMessages = messages.filter(msg => msg.timestamp >= cutoffTime);
            
            if (freshMessages.length === 0) {
                // Remove empty memory arrays
                this.memories.delete(username);
            } else if (freshMessages.length < messages.length) {
                // Update with only fresh messages
                this.memories.set(username, freshMessages);
            }
        }
    }
    
    /**
     * Start automatic cleanup interval
     */
    startCleanupInterval() {
        // Run cleanup every 5 minutes
        setInterval(() => {
            this.cleanupOldMessages();
        }, 5 * 60 * 1000);
    }
    
    /**
     * Get stats about the memory system
     * @returns {Object} - Stats about memory usage
     */
    getStats() {
        return {
            userCount: this.memories.size,
            totalMessages: Array.from(this.memories.values())
                .reduce((total, messages) => total + messages.length, 0),
            oldestMessage: this.getOldestMessageTime()
        };
    }
    
    /**
     * Get the timestamp of the oldest message in memory
     * @returns {number|null} - Timestamp or null if no messages
     */
    getOldestMessageTime() {
        let oldest = null;
        
        for (const messages of this.memories.values()) {
            for (const msg of messages) {
                if (oldest === null || msg.timestamp < oldest) {
                    oldest = msg.timestamp;
                }
            }
        }
        
        return oldest;
    }
}

module.exports = MemoryHandler;