var fs = require('fs');
var cp = require('child_process');
var glob = require('glob');
var ini = require('ini');
var Cache = require('./cache');

/**
 * Load a JSON file
 *
 * @param filePath The path of the json file
 * @return Promise
 */
exports.loadJSON = 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 || {};

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

  return new Promise(function(resolve, reject) {
    cp.exec(execPath, function(err) {
      if(err) return reject(err);
      return resolve();
    });
  });
};

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);
  });
};