const express = require('express');
const fs = require('fs').promises;
const path = require('path');

const {
    plugins,
    plugin_name_to_folder_name,
    plugin_data_path,
} = require('../../../public/script.js');

const extensionName = "Amily-Databin";
const extensionVersion = "0.0.1-a";

const storageBasePath = path.join(plugin_data_path, 'cc.amily49.amily-databin');
let sourceTypes = {}; // Will be loaded from sourcetype.json

/**
 * Builds a safe file path and prevents path traversal attacks.
 */
function getSafeFilePath(source, objName, file) {
    if (typeof source !== 'string' && typeof source !== 'number' || typeof objName !== 'string' || typeof file !== 'string') {
        return null;
    }
    const sanitize = (part) => String(part).replace(/\.\./g, '').replace(/[/\]/g, '');
    const safeSource = sanitize(source);
    const safeObjName = sanitize(objName);
    const safeFile = sanitize(file);
    
    if (!safeSource || !safeObjName || !safeFile) return null;
    
    return path.join(storageBasePath, safeSource, safeObjName, safeFile);
}

// #region Server-side Business Logic per SourceType
// These functions implement the "strategy" for each source type.

/** Generic save handler */
async function defaultSaveStrategy(filePath, data) {
    await fs.mkdir(path.dirname(filePath), { recursive: true });
    await fs.writeFile(filePath, JSON.stringify(data, null, 2), 'utf8');
}

// #endregion

(async () => {
    try {
        // Load source types from the file on startup.
        const sourceTypesRaw = await fs.readFile(path.join(__dirname, 'sourcetype.json'), 'utf8');
        sourceTypes = JSON.parse(sourceTypesRaw);
        
        // Ensure the base storage directory exists.
        await fs.mkdir(storageBasePath, { recursive: true });
    } catch (error) {
        console.error(`[${extensionName}] Critical startup error:`, error);
        return; // Stop loading the plugin
    }

    const router = express.Router();

    // Endpoint to serve the source type map to the client
    router.get('/sourcetype', (req, res) => {
        res.json(sourceTypes);
    });

    router.get('/data', async (req, res) => {
        const filePath = getSafeFilePath(req.query.source, req.query.objName, req.query.file);
        if (!filePath) return res.status(400).send("Invalid parameters.");

        try {
            const fileContent = await fs.readFile(filePath, 'utf8');
            res.json(JSON.parse(fileContent));
        } catch (error) {
            if (error.code === 'ENOENT') return res.status(404).send('Not found.');
            console.error(`[${extensionName}] Error reading file ${filePath}:`, error);
            res.status(500).send('Internal Server Error');
        }
    });

    router.post('/data', async (req, res) => {
        const { source, objName, file, data } = req.body;
        const filePath = getSafeFilePath(source, objName, file);

        if (!filePath) return res.status(400).send("Invalid parameters.");
        if (data === undefined) return res.status(400).send("'data' is required.");

        const sourceType = parseInt(source, 10);

        try {
            // Strategy pattern based on source type
            switch (sourceType) {
                case sourceTypes.CHAT_LOG:
                case sourceTypes.CHARACTER_CARD:
                case sourceTypes.WORLD_BOOK:
                    // For now, all implemented types use the default save strategy.
                    await defaultSaveStrategy(filePath, data);
                    res.status(200).send('Data saved successfully.');
                    break;
                
                default:
                    // If the source type is known but not implemented, or unknown.
                    res.status(501).send(`Save handler for source type '${sourceType}' is not implemented.`);
                    break;
            }
        } catch (error) {
            console.error(`[${extensionName}] Error in POST /data for source ${sourceType}:`, error);
            res.status(500).send('Internal Server Error');
        }
    });
    
    router.delete('/data', async (req, res) => {
        const filePath = getSafeFilePath(req.query.source, req.query.objName, req.query.file);
        if (!filePath) return res.status(400).send("Invalid parameters.");

        try {
            await fs.unlink(filePath);
            res.status(200).send('Data deleted successfully.');
        } catch (error) {
            if (error.code === 'ENOENT') return res.status(200).send('Not found.');
            console.error(`[${extensionName}] Error deleting file ${filePath}:`, error);
            res.status(500).send('Internal Server Error');
        }
    });

    plugins[extensionName] = {
        name: extensionName,
        version: extensionVersion,
        is_enabled: true,
        folder_name: plugin_name_to_folder_name[extensionName],
        router: router,
        assets: ['client.js'],
    };

    console.log(`[${extensionName}] version ${extensionVersion} loaded. Storage path: ${storageBasePath}`);
})();