import http from "node:http";
import { join } from "node:path";
import { readFileSync, readdirSync } from "node:fs";
import { fileURLToPath } from "node:url";
import { dirname } from "node:path";
import vm from "node:vm";
import axios from "axios";
import { v4 as uuidv4 } from "uuid";
import jwt from "jsonwebtoken";
import { create as xmlBuilder } from "xmlbuilder2";
import { logger } from "./logger.js";

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

const globalVMContext = {
  URLSearchParams,
  console: logger,
  crypto,
  axios,
  uuidv4,
  jwt,
  xmlBuilder,
};

let globalVariableContext = {};

/**
 * Load all JSON files from global/ directory and make them available as global objects
 * Pattern: global/filename.json -> globalVariableContext['filename']
 */
function loadGlobalObjects() {
  const globalDir = join(__dirname, "..", "global");

  try {
    const files = readdirSync(globalDir).filter(
      (f) => f.endsWith(".json") && !f.endsWith(".example"),
    );

    files.forEach((file) => {
      const objectName = file.replace(".json", "");
      const filePath = join(globalDir, file);

      try {
        const content = readFileSync(filePath, "utf-8");
        const data = JSON.parse(content);
        globalVariableContext[objectName] = data;
        logger.info(`Loaded global object: ${objectName}`, {
          file: file,
          keys: Object.keys(data),
        });
      } catch (error) {
        logger.error(`Failed to load global object from ${file}`, {
          error: error.message,
        });
        throw error;
      }
    });

    logger.info(`Loaded ${files.length} global objects from ${globalDir}`);
  } catch (error) {
    logger.error("Failed to load global objects", {
      directory: globalDir,
      error: error.message,
    });
    throw error;
  }
}

/**
 * Load configuration from config/default.json
 * Merges with environment variables (ENV takes precedence)
 *
 * @returns {Object} Configuration object
 */
function loadConfig() {
  const configPath = join(__dirname, "..", "config", "default.json");
  const configData = readFileSync(configPath, "utf-8");
  const config = JSON.parse(configData);

  // Merge environment variables (ENV vars take precedence)
  config.server.port = process.env.PORT
    ? parseInt(process.env.PORT, 10)
    : config.server.port;
  config.server.host = process.env.HOST || config.server.host;
  config.logging.level = process.env.LOG_LEVEL || config.logging.level;

  return config;
}

/**
 * Validate configuration
 * @param {Object} config - Configuration object
 * @throws {Error} If configuration is invalid
 */
function validateConfig(config) {
  const errors = [];

  // Validate server configuration
  if (
    !config.server.port ||
    config.server.port < 1 ||
    config.server.port > 65535
  ) {
    errors.push("Invalid server.port (must be 1-65535)");
  }

  if (errors.length > 0) {
    throw new Error(`Configuration validation failed:\n${errors.join("\n")}`);
  }
}

/**
 * Start the HTTP server
 */
async function startServer() {
  try {
    // Load configuration into global.config
    global.config = loadConfig();

    // Load global objects from global/ directory (e.g., service account keys)
    loadGlobalObjects();

    logger.info("Starting Proxy Script Server...");
    logger.info(
      `Configuration loaded: ${JSON.stringify({
        port: global.config.server.port,
        host: global.config.server.host,
        logLevel: global.config.logging.level,
      })}`,
    );

    // Validate configuration
    validateConfig(global.config);
    logger.info("Configuration validated successfully");

    const proxyPath = join(__dirname, "proxy.js");
    const proxyCode = readFileSync(proxyPath, "utf-8");
    const script = new vm.Script(proxyCode, { filename: "proxy.js" });

    // Create HTTP server that delegates all requests to proxy
    const server = http.createServer((req, res) => {
      try {
        // Create a context with all globals that proxy.js needs
        const context = vm.createContext({
          ...globalVMContext,
          ...globalVariableContext,
          req,
          res,
        });
        script.runInContext(context);
      } catch (error) {
        logger.error("Request handling failed", {
          error: error.message,
          stack: error.stack,
        });
        res.statusCode = 500;
        res.end("Internal Server Error");
      }
    });

    // Graceful shutdown
    const shutdown = () => {
      logger.info("\nShutting down gracefully...");
      server.close(() => {
        logger.info("Server closed");
        process.exit(0);
      });

      // Force shutdown after 10 seconds
      setTimeout(() => {
        logger.error("Forced shutdown after timeout");
        process.exit(1);
      }, 10000);
    };

    process.on("SIGTERM", shutdown);
    process.on("SIGINT", shutdown);

    // Start listening
    server.listen(global.config.server.port, global.config.server.host, () => {
      logger.info("Server listening", {
        port: global.config.server.port,
        host: global.config.server.host,
      });
    });
  } catch (error) {
    logger.error("Failed to start server", {
      error: error.message,
      stack: error.stack,
    });
    process.exit(1);
  }
}

// Start the server
startServer();