/*
# MIT License

### Copyright (C) 2011 by Charlie McConnell

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

var fs = require('fs'),
    path = require('path');

module.exports = ncp;
ncp.ncp = ncp;

function ncp (source, dest, options, callback) {
  var cback = callback;

  if (!callback) {
    cback = options;
    options = {};
  }

  var basePath = process.cwd(),
      currentPath = path.resolve(basePath, source),
      targetPath = path.resolve(basePath, dest),
      filter = options.filter,
      rename = options.rename,
      transform = options.transform,
      clobber = options.clobber !== false,
      modified = options.modified,
      dereference = options.dereference,
      errs = null,
      started = 0,
      finished = 0,
      running = 0,
      limit = options.limit || ncp.limit || 16;

  limit = (limit < 1) ? 1 : (limit > 512) ? 512 : limit;

  startCopy(currentPath);
  
  function startCopy(source) {
    started++;
    if (filter) {
      if (filter instanceof RegExp) {
        if (!filter.test(source)) {
          return cb(true);
        }
      }
      else if (typeof filter === 'function') {
        if (!filter(source)) {
          return cb(true);
        }
      }
    }
    return getStats(source);
  }

  function getStats(source) {
    var stat = dereference ? fs.stat : fs.lstat;
    if (running >= limit) {
      return setImmediate(function () {
        getStats(source);
      });
    }
    running++;
    stat(source, function (err, stats) {
      var item = {};
      if (err) {
        return onError(err);
      }

      // We need to get the mode from the stats object and preserve it.
      item.name = source;
      item.mode = stats.mode;
      item.mtime = stats.mtime; //modified time
      item.atime = stats.atime; //access time

      if (stats.isDirectory()) {
        return onDir(item);
      }
      else if (stats.isFile()) {
        return onFile(item);
      }
      else if (stats.isSymbolicLink()) {
        // Symlinks don't really need to know about the mode.
        return onLink(source);
      }
    });
  }

  function onFile(file) {
    var target = file.name.replace(currentPath, targetPath);
    if(rename) {
      target =  rename(target);
    }
    isWritable(target, function (writable) {
      if (writable) {
        return copyFile(file, target);
      }
      if(clobber) {
        rmFile(target, function () {
          copyFile(file, target);
        });
      }
      if (modified) {
        var stat = dereference ? fs.stat : fs.lstat;
        stat(target, function(err, stats) {
            //if souce modified time greater to target modified time copy file
            if (file.mtime.getTime()>stats.mtime.getTime())
                copyFile(file, target);
            else return cb();
        });
      }
      else {
        return cb();
      }
    });
  }

  function copyFile(file, target) {
    var readStream = fs.createReadStream(file.name),
        writeStream = fs.createWriteStream(target, { mode: file.mode });
    
    readStream.on('error', onError);
    writeStream.on('error', onError);
    
    if(transform) {
      transform(readStream, writeStream, file);
    } else {
      writeStream.on('open', function() {
        readStream.pipe(writeStream);
      });
    }
    writeStream.once('finish', function() {
        if (modified) {
            //target file modified date sync.
            fs.utimesSync(target, file.atime, file.mtime);
            cb();
        }
        else cb();
    });
  }

  function rmFile(file, done) {
    fs.unlink(file, function (err) {
      if (err) {
        return onError(err);
      }
      return done();
    });
  }

  function onDir(dir) {
    var target = dir.name.replace(currentPath, targetPath);
    isWritable(target, function (writable) {
      if (writable) {
        return mkDir(dir, target);
      }
      copyDir(dir.name);
    });
  }

  function mkDir(dir, target) {
    fs.mkdir(target, dir.mode, function (err) {
      if (err) {
        return onError(err);
      }
      copyDir(dir.name);
    });
  }

  function copyDir(dir) {
    fs.readdir(dir, function (err, items) {
      if (err) {
        return onError(err);
      }
      items.forEach(function (item) {
        startCopy(path.join(dir, item));
      });
      return cb();
    });
  }

  function onLink(link) {
    var target = link.replace(currentPath, targetPath);
    fs.readlink(link, function (err, resolvedPath) {
      if (err) {
        return onError(err);
      }
      checkLink(resolvedPath, target);
    });
  }

  function checkLink(resolvedPath, target) {
    if (dereference) {
      resolvedPath = path.resolve(basePath, resolvedPath);
    }
    isWritable(target, function (writable) {
      if (writable) {
        return makeLink(resolvedPath, target);
      }
      fs.readlink(target, function (err, targetDest) {
        if (err) {
          return onError(err);
        }
        if (dereference) {
          targetDest = path.resolve(basePath, targetDest);
        }
        if (targetDest === resolvedPath) {
          return cb();
        }
        return rmFile(target, function () {
          makeLink(resolvedPath, target);
        });
      });
    });
  }

  function makeLink(linkPath, target) {
    fs.symlink(linkPath, target, function (err) {
      if (err) {
        return onError(err);
      }
      return cb();
    });
  }

  function isWritable(path, done) {
    fs.lstat(path, function (err) {
      if (err) {
        if (err.code === 'ENOENT') return done(true);
        return done(false);
      }
      return done(false);
    });
  }

  function onError(err) {
    if (options.stopOnError) {
      return cback(err);
    }
    else if (!errs && options.errs) {
      errs = fs.createWriteStream(options.errs);
    }
    else if (!errs) {
      errs = [];
    }
    if (typeof errs.write === 'undefined') {
      errs.push(err);
    }
    else { 
      errs.write(err.stack + '\n\n');
    }
    return cb();
  }

  function cb(skipped) {
    if (!skipped) running--;
    finished++;
    if ((started === finished) && (running === 0)) {
      if (cback !== undefined ) {
        return errs ? cback(errs) : cback(null);
      }
    }
  }
}