const path = require('path');
const fs = require('fs');
const { USER_DIRECTORY_TEMPLATE, DEFAULT_USER, PUBLIC_DIRECTORIES } = require('./constants');
const { getConfigValue, color, delay } = require('./util');
const express = require('express');

const DATA_ROOT = getConfigValue('dataRoot', './data');

/**
 * @typedef {Object} User
 * @property {string} uuid - The user's id
 * @property {string} handle - The user's short handle. Used for directories and other references
 * @property {string} name - The user's name. Displayed in the UI
 * @property {number} created - The timestamp when the user was created
 * @property {string} password - SHA256 hash of the user's password
 */

/**
 * @typedef {Object} UserDirectoryList
 * @property {string} root - The root directory for the user
 * @property {string} thumbnails - The directory where the thumbnails are stored
 * @property {string} thumbnailsBg - The directory where the background thumbnails are stored
 * @property {string} thumbnailsAvatar - The directory where the avatar thumbnails are stored
 * @property {string} worlds - The directory where the WI are stored
 * @property {string} user - The directory where the user's public data is stored
 * @property {string} avatars - The directory where the avatars are stored
 * @property {string} userImages - The directory where the images are stored
 * @property {string} groups - The directory where the groups are stored
 * @property {string} groupChats - The directory where the group chats are stored
 * @property {string} chats - The directory where the chats are stored
 * @property {string} characters - The directory where the characters are stored
 * @property {string} backgrounds - The directory where the backgrounds are stored
 * @property {string} novelAI_Settings - The directory where the NovelAI settings are stored
 * @property {string} koboldAI_Settings - The directory where the KoboldAI settings are stored
 * @property {string} openAI_Settings - The directory where the OpenAI settings are stored
 * @property {string} textGen_Settings - The directory where the TextGen settings are stored
 * @property {string} themes - The directory where the themes are stored
 * @property {string} movingUI - The directory where the moving UI data is stored
 * @property {string} extensions - The directory where the extensions are stored
 * @property {string} instruct - The directory where the instruct templates is stored
 * @property {string} context - The directory where the context templates is stored
 * @property {string} quickreplies - The directory where the quick replies are stored
 * @property {string} assets - The directory where the assets are stored
 * @property {string} comfyWorkflows - The directory where the ComfyUI workflows are stored
 * @property {string} files - The directory where the uploaded files are stored
 * @property {string} vectors - The directory where the vectors are stored
 */

/**
 * Perform migration from the old user data format to the new one.
 */
async function migrateUserData() {
    const publicDirectory = path.join(process.cwd(), 'public');

    // No need to migrate if the characters directory doesn't exists
    if (!fs.existsSync(path.join(publicDirectory, 'characters'))) {
        return;
    }

    const TIMEOUT = 10;

    console.log();
    console.log(color.magenta('Preparing to migrate user data...'));
    console.log(`All public data will be moved to the ${DATA_ROOT} directory.`);
    console.log('This process may take a while depending on the amount of data to move.');
    console.log(`Backups will be placed in the ${PUBLIC_DIRECTORIES.backups} directory.`);
    console.log(`The process will start in ${TIMEOUT} seconds. Press Ctrl+C to cancel.`);

    for (let i = TIMEOUT; i > 0; i--) {
        console.log(`${i}...`);
        await delay(1000);
    }

    console.log(color.magenta('Starting migration... Do not interrupt the process!'));

    const userDirectories = getUserDirectories(DEFAULT_USER.handle);

    const dataMigrationMap = [
        {
            old: path.join(publicDirectory, 'assets'),
            new: userDirectories.assets,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'backgrounds'),
            new: userDirectories.backgrounds,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'characters'),
            new: userDirectories.characters,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'chats'),
            new: userDirectories.chats,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'context'),
            new: userDirectories.context,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'group chats'),
            new: userDirectories.groupChats,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'groups'),
            new: userDirectories.groups,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'instruct'),
            new: userDirectories.instruct,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'KoboldAI Settings'),
            new: userDirectories.koboldAI_Settings,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'movingUI'),
            new: userDirectories.movingUI,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'NovelAI Settings'),
            new: userDirectories.novelAI_Settings,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'OpenAI Settings'),
            new: userDirectories.openAI_Settings,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'QuickReplies'),
            new: userDirectories.quickreplies,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'TextGen Settings'),
            new: userDirectories.textGen_Settings,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'themes'),
            new: userDirectories.themes,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'user'),
            new: userDirectories.user,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'User Avatars'),
            new: userDirectories.avatars,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'worlds'),
            new: userDirectories.worlds,
            file: false,
        },
        {
            old: path.join(publicDirectory, 'scripts/extensions/third-party'),
            new: userDirectories.extensions,
            file: false,
        },
        {
            old: path.join(process.cwd(), 'thumbnails'),
            new: userDirectories.thumbnails,
            file: false,
        },
        {
            old: path.join(process.cwd(), 'vectors'),
            new: userDirectories.vectors,
            file: false,
        },
        {
            old: path.join(process.cwd(), 'secrets.json'),
            new: path.join(userDirectories.root, 'secrets.json'),
            file: true,
        },
        {
            old: path.join(publicDirectory, 'settings.json'),
            new: path.join(userDirectories.root, 'settings.json'),
            file: true,
        },
        {
            old: path.join(publicDirectory, 'stats.json'),
            new: path.join(userDirectories.root, 'stats.json'),
            file: true,
        },
    ];

    const currentDate = new Date().toISOString().split('T')[0];
    const backupDirectory = path.join(process.cwd(), PUBLIC_DIRECTORIES.backups, '_migration', currentDate);

    if (!fs.existsSync(backupDirectory)) {
        fs.mkdirSync(backupDirectory, { recursive: true });
    }

    const errors = [];

    for (const migration of dataMigrationMap) {
        console.log(`Migrating ${migration.old} to ${migration.new}...`);

        try {
            if (!fs.existsSync(migration.old)) {
                console.log(color.yellow(`Skipping migration of ${migration.old} as it does not exist.`));
                continue;
            }

            if (migration.file) {
                // Copy the file to the new location
                fs.cpSync(migration.old, migration.new, { force: true });
                // Move the file to the backup location
                fs.renameSync(migration.old, path.join(backupDirectory, path.basename(migration.old)));
            } else {
                // Copy the directory to the new location
                fs.cpSync(migration.old, migration.new, { recursive: true, force: true });
                // Move the directory to the backup location
                fs.renameSync(migration.old, path.join(backupDirectory, path.basename(migration.old)));
            }
        } catch (error) {
            console.error(color.red(`Error migrating ${migration.old} to ${migration.new}:`), error.message);
            errors.push(migration.old);
        }
    }

    if (errors.length > 0) {
        console.log(color.red('Migration completed with errors. Move the following files manually:'));
        errors.forEach(error => console.error(error));
    }

    console.log(color.green('Migration completed!'));
}

/**
 * Initializes the user storage. Currently a no-op.
 * @returns {Promise<void>}
 */
async function initUserStorage() {
    return Promise.resolve();
}

/**
 * Gets a user for the current request. Hard coded to return the default user.
 * @param {import('express').Request} _req - The request object. Currently unused.
 * @returns {Promise<string>} - The user's handle
 */
async function getCurrentUserHandle(_req) {
    return DEFAULT_USER.handle;
}

/**
 * Gets a list of all user handles. Currently hard coded to return the default user's handle.
 * @returns {Promise<string[]>} - The list of user handles
 */
async function getAllUserHandles() {
    return [DEFAULT_USER.handle];
}

/**
 * Gets the directories listing for the provided user.
 * @param {import('express').Request} req - The request object
 * @returns {Promise<UserDirectoryList>} - The user's directories like {worlds: 'data/user0/worlds/', ...
 */
async function getCurrentUserDirectories(req) {
    const handle = await getCurrentUserHandle(req);
    return getUserDirectories(handle);
}

/**
 * Gets the directories listing for the provided user.
 * @param {string} handle User handle
 * @returns {UserDirectoryList} User directories
 */
function getUserDirectories(handle) {
    const directories = structuredClone(USER_DIRECTORY_TEMPLATE);
    for (const key in directories) {
        directories[key] = path.join(DATA_ROOT, handle, USER_DIRECTORY_TEMPLATE[key]);
    }
    return directories;
}

/**
 * Middleware to add user data to the request object.
 * @returns {import('express').RequestHandler}
 */
function userDataMiddleware() {
    /**
     * Middleware to add user data to the request object.
     * @param {import('express').Request} req Request object
     * @param {import('express').Response} res Response object
     * @param {import('express').NextFunction} next Next function
     */
    return async (req, res, next) => {
        const directories = await getCurrentUserDirectories(req);
        req.user = {
            profile: DEFAULT_USER,
            directories: directories,
        };
        next();
    };
}

/**
 * Creates a route handler for serving files from a specific directory.
 * @param {(req: import('express').Request) => string} directoryFn A function that returns the directory path to serve files from
 * @returns {import('express').RequestHandler}
 */
function createRouteHandler(directoryFn) {
    return async (req, res) => {
        try {
            const directory = directoryFn(req);
            const filePath = decodeURIComponent(req.params[0]);
            return res.sendFile(filePath, { root: directory });
        } catch (error) {
            console.error(error);
            return res.sendStatus(404);
        }
    };
}

/**
 * Express router for serving files from the user's directories.
 */
const router = express.Router();
router.use('/backgrounds/*', createRouteHandler(req => req.user.directories.backgrounds));
router.use('/characters/*', createRouteHandler(req => req.user.directories.characters));
router.use('/User%20Avatars/*', createRouteHandler(req => req.user.directories.avatars));
router.use('/assets/*', createRouteHandler(req => req.user.directories.assets));
router.use('/user/images/*', createRouteHandler(req => req.user.directories.userImages));
router.use('/user/files/*', createRouteHandler(req => req.user.directories.files));
router.use('/scripts/extensions/third-party/*', createRouteHandler(req => req.user.directories.extensions));

module.exports = {
    initUserStorage,
    getCurrentUserDirectories,
    getCurrentUserHandle,
    getAllUserHandles,
    getUserDirectories,
    userDataMiddleware,
    migrateUserData,
    router,
};