/**
 * All writing related code here. This is so that we can separate the async code from sync code
 * for testability
 */
var qfs = require('q-fs');
var Q = require('qq');
var OUTPUT_DIR = "build/docs/";
var fs = require('fs');

exports.output = function(file, content) {
  var fullPath = OUTPUT_DIR + file;
  var dir = parent(fullPath);
  return Q.when(exports.makeDir(dir), function(error) {
    qfs.write(fullPath, exports.toString(content));
  });
};

//recursively create directory
exports.makeDir = function(path) {
  var parts = path.split(/\//);
  var path = ".";
  //Sequentially create directories
  var done = Q.defer();
  (function createPart() {

    if(!parts.length) {
      done.resolve();
    } else {
      path += "/" + parts.shift();
      qfs.isDirectory(path).then(function(isDir) {
        if(!isDir) {
          qfs.makeDirectory(path);
        }
        createPart();
      });
    }
  })();
  return done.promise;
};

exports.copyTpl = function(filename) {
  return exports.copy('docs/src/templates/' + filename, OUTPUT_DIR + filename);
};

/* Copy files from one place to another.
 * @param from{string} path of the source file to be copied
 * @param to{string} path of where the copied file should be stored
 * @param  transform{function=} transfromation function to be applied before return
 */
exports.copy = function(from, to, transform) {
  var args = Array.prototype.slice.call(arguments, 3);

  // We have to use binary reading, Since some characters are unicode.
  return qfs.read(from, 'b').then(function(content) {
    if (transform) {
      args.unshift(content.toString());
      content = transform.apply(null, args);
    }
    qfs.write(to, content);
  });
}

/* Replace placeholders in content accordingly
 * @param content{string} content to be modified
 * @param replacements{obj} key and value pairs in which key will be replaced with value in content
 */
exports.replace = function(content, replacements) {
  for(key in replacements) {
    content = content.replace(key, replacements[key]);
  }
  return content;
}

exports.copyDir = function copyDir(dir) {
  return qfs.listDirectoryTree('docs/' + dir).then(function(dirs) {
    var done;
    dirs.forEach(function(dirToMake) {
      done = Q.when(done, function() {
       return exports.makeDir("./build/" + dirToMake);
      });
    });
    return done;
  }).then(function() {
    return qfs.listTree('docs/' + dir);
  }).then(function(files) {
    files.forEach( function(file) {
      exports.copy(file,'./build/' + file);
    });
  });
};

exports.merge = function(srcs, to) {
  return merge(srcs.map(function(src) { return 'docs/src/templates/' + src; }), OUTPUT_DIR + to);
};

function merge(srcs, to) {
  var contents = [];
  //Sequentially read file
  var done;
  srcs.forEach(function(src) {
    done = Q.when(done, function(content) {
      if(content) contents.push(content);
      return qfs.read(src, 'b');
    });
  });

  // write to file
  return Q.when(done, function(content) {
    contents.push(content);
    qfs.write(to, contents.join('\n'));
  });
}

//----------------------- Synchronous Methods ----------------------------------

function parent(file) {
  var parts = file.split('/');
  parts.pop();
  return parts.join('/');
}


exports.toString = function toString(obj) {
  switch (typeof obj) {
  case 'string':
    return obj;
  case 'object':
    if (obj instanceof Array) {
      obj.forEach(function(value, key) {
        obj[key] = toString(value);
      });
      return obj.join('');
    } else {
      return JSON.stringify(obj);
    }
  }
  return obj;
};


function noop() {};
