/* jshint node:true */
var fs = require('fs');
var cp = require('child_process');
var glob = require('glob');
var ini = require('ini');
var Cache = require('./cache');
var request = require('request');

var HTTP_REGEX = /^https?:\/\//i;
/**
 * Load a JSON file (http or local)
 *
 * @param filePath The path of the json file
 * @return Promise
 */
exports.loadJSON = function(jsonUrl) {
  if( HTTP_REGEX.test(jsonUrl) ) {
    return exports.fetchRemoteJSON(jsonUrl);
  } else {
    return exports.loadLocalJSON(jsonUrl);
  }
};

/**
 * Load a remote JSON file via http
 *
 * @param filePath The path of the json file
 * @return Promise
 */
exports.fetchRemoteJSON = function(fileUrl) {
  return new Promise(function(resolve, reject) {
    request(fileUrl, { followRedirect: true, json: true }, function (err, res, body) {
      if(err) return reject(err);
      return resolve(body);
    });
  });
};


/**
 * Load a local JSON file
 *
 * @param filePath The path of the json file
 * @return Promise
 */
exports.loadLocalJSON = function(filePath) {
  return new Promise(function(resolve, reject) {
    fs.readFile(filePath, 'utf8', function(err, fileContent) {
      if(err) return reject(err);
      try {
        var json = JSON.parse(fileContent);
        return resolve(json);
      } catch(err) {
        return reject(err);
      }
    });
  });
};

exports.saveJSON = function(filePath, obj) {

  var jsonStr = JSON.stringify(obj, null, 2);

  return new Promise(function(resolve, reject) {
    fs.writeFile(filePath, jsonStr, function(err) {
      if(err) return reject(err);
      return resolve();
    });
  });

};

/**
 * Load a INI file
 *
 * @param filePath The path of the json file
 * @return Promise
 */
exports.loadINIFile = function(filePath) {
  return new Promise(function(resolve, reject) {
    fs.readFile(filePath, 'utf8', function(err, content) {
      if(err) return reject(err);
      try {
        var decoded = ini.decode(content);
        return resolve(decoded);
      } catch(err) {
        return reject(err);
      }
    });
  });
};

exports.clearFreeDesktopFlags = function(exec) {
  return exec.replace(/%[uUdDfFnNickvm]/g, '');
};

exports.runApp = function(execPath, opts) {

  opts = opts || {};

  return new Promise(function(resolve, reject) {
    try {

      if(opts.clearFreeDesktopFlags) {
        execPath = exports.clearFreeDesktopFlags(execPath);
      }

      var isDev = process.env.NODE_ENV === 'development';

      var child = cp.spawn(execPath, {
        detached: true,
        shell: true,
        stdio: [
          'ignore',
          isDev ? process.stdout : 'ignore',
          isDev ? process.stderr : 'ignore'
        ]
      });

      // Detach the child process
      child.unref();

    } catch(err) {
      return reject(err);
    }

    // Execute the rest after all I/O operations in this tick
    let immediateId = setImmediate(() => {

      // We do not want to be notified of child events after launch
      child.removeAllListeners();

      try {
        // Check if the child process is still alive, should throw otherwise
        child.kill(0);
      } catch(err) {
        return reject(err);
      }

      return resolve(child);

    });

    // If the child process exit with an exit code != 0, reject the promise
    child.once('close', code => {
      if(code === 0) return;
      clearImmediate(immediateId);
      child.removeAllListeners();
      return reject(`Program exited with a exit code "${code}"`);
    });

    // If an error occurs during the process launch, reject the promise
    child.once('error', err => {
      clearImmediate(immediateId);
      child.removeAllListeners();
      return reject(err);
    });

  });
};

var _searchCache = new Cache();

exports.findFiles = function(pattern, opts) {
  return new Promise(function(resolve, reject) {

    var cachedResult = _searchCache.get([pattern, opts]);
    if( cachedResult !== undefined) {
      return resolve(cachedResult);
    }

    glob(pattern, opts, function(err, files) {
      if(err) return reject(err);
      _searchCache.set([pattern, opts], files);
      return resolve(files);
    });

  });
};

exports.exists = function(filePath) {
  return new Promise(function(resolve) {
    fs.exists(filePath, resolve);
  });
};