import fs from 'fs';
import path from 'path';
import crypto from 'crypto';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const USERS_FILE = process.env.PICUPPER_USERS_FILE || path.join(__dirname, 'users.json');

/**
 * Load users from JSON file
 */
export function loadUsers() {
    if (!fs.existsSync(USERS_FILE)) {
        return {};
    }

    try {
        const data = fs.readFileSync(USERS_FILE, 'utf-8');
        return JSON.parse(data);
    } catch (error) {
        console.error('Error loading users file:', error.message);
        return {};
    }
}

/**
 * Save users to JSON file
 */
export function saveUsers(users) {
    fs.writeFileSync(USERS_FILE, JSON.stringify(users, null, 2));
}

/**
 * Generate a secure API key
 */
export function generateApiKey() {
    return crypto.randomBytes(32).toString('hex');
}

/**
 * Add a new user with generated API key
 */
export function addUser(username, description = '') {
    const users = loadUsers();

    if (users[username]) {
        throw new Error(`User '${username}' already exists`);
    }

    const apiKey = generateApiKey();

    users[username] = {
        apiKey,
        description,
        createdAt: new Date().toISOString(),
        enabled: true
    };

    saveUsers(users);
    return apiKey;
}

/**
 * Remove a user
 */
export function removeUser(username) {
    const users = loadUsers();

    if (!users[username]) {
        throw new Error(`User '${username}' not found`);
    }

    delete users[username];
    saveUsers(users);
}

/**
 * Regenerate API key for a user
 */
export function regenerateApiKey(username) {
    const users = loadUsers();

    if (!users[username]) {
        throw new Error(`User '${username}' not found`);
    }

    const newApiKey = generateApiKey();
    users[username].apiKey = newApiKey;
    users[username].keyRegeneratedAt = new Date().toISOString();

    saveUsers(users);
    return newApiKey;
}

/**
 * Enable/disable a user
 */
export function setUserEnabled(username, enabled) {
    const users = loadUsers();

    if (!users[username]) {
        throw new Error(`User '${username}' not found`);
    }

    users[username].enabled = enabled;
    saveUsers(users);
}

/**
 * List all users (without exposing full API keys)
 */
export function listUsers() {
    const users = loadUsers();

    return Object.entries(users).map(([username, data]) => ({
        username,
        description: data.description,
        createdAt: data.createdAt,
        enabled: data.enabled,
        keyPreview: data.apiKey.substring(0, 8) + '...'
    }));
}

/**
 * Validate an API key and return the username if valid
 */
export function validateApiKey(apiKey) {
    const users = loadUsers();

    for (const [username, data] of Object.entries(users)) {
        if (data.apiKey === apiKey && data.enabled) {
            return username;
        }
    }

    return null;
}