// Copyright Joyent, Inc. and other Node contributors.
//
// 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.

// Based on https://github.com/joyent/node/blob/41e53e557992a7d552a8e23de035f9463da25c99/lib/path.js
define(function() {

  // resolves . and .. elements in a path array with directory names there
  // must be no slashes, empty elements, or device names (c:\) in the array
  // (so also no leading and trailing slashes - it does not distinguish
  // relative and absolute paths)
  function normalizeArray(parts, allowAboveRoot) {
    // if the path tries to go above the root, `up` ends up > 0
    var up = 0;
    for (var i = parts.length - 1; i >= 0; i--) {
      var last = parts[i];
      if (last === '.') {
        parts.splice(i, 1);
      } else if (last === '..') {
        parts.splice(i, 1);
        up++;
      } else if (up) {
        parts.splice(i, 1);
        up--;
      }
    }

    // if the path is allowed to go above the root, restore leading ..s
    if (allowAboveRoot) {
      for (; up--; up) {
        parts.unshift('..');
      }
    }

    return parts;
  }

  // Split a filename into [root, dir, basename, ext], unix version
  // 'root' is just a slash, or nothing.
  var splitPathRe =
        /^(\/?)([\s\S]+\/(?!$)|\/)?((?:\.{1,2}$|[\s\S]+?)?(\.[^.\/]*)?)$/;
  var splitPath = function(filename) {
    var result = splitPathRe.exec(filename);
    return [result[1] || '', result[2] || '', result[3] || '', result[4] || ''];
  };

  // path.resolve([from ...], to)
  function resolve() {
    var resolvedPath = '',
        resolvedAbsolute = false;

    for (var i = arguments.length - 1; i >= -1 && !resolvedAbsolute; i--) {
      var path = arguments[i];

      // Skip empty and invalid entries
      if (typeof path !== 'string' || !path) {
        continue;
      }

      resolvedPath = path + '/' + resolvedPath;
      resolvedAbsolute = path.charAt(0) === '/';
    }

    // At this point the path should be resolved to a full absolute path, but
    // handle relative paths to be safe (might happen when process.cwd() fails)

    // Normalize the path
    resolvedPath = normalizeArray(resolvedPath.split('/').filter(function(p) {
      return !!p;
    }), !resolvedAbsolute).join('/');

    return ((resolvedAbsolute ? '/' : '') + resolvedPath) || '.';
  }

  // path.normalize(path)
  function normalize(path) {
    var isAbsolute = path.charAt(0) === '/',
        trailingSlash = path.substr(-1) === '/';

    // Normalize the path
    path = normalizeArray(path.split('/').filter(function(p) {
      return !!p;
    }), !isAbsolute).join('/');

    if (!path && !isAbsolute) {
      path = '.';
    }
    if (path && trailingSlash) {
      path += '/';
    }

    return (isAbsolute ? '/' : '') + path;
  }

  function join() {
    var paths = Array.prototype.slice.call(arguments, 0);
    return normalize(paths.filter(function(p, index) {
      return p && typeof p === 'string';
    }).join('/'));
  }

  // path.relative(from, to)
  function relative(from, to) {
    from = exports.resolve(from).substr(1);
    to = exports.resolve(to).substr(1);

    function trim(arr) {
      var start = 0;
      for (; start < arr.length; start++) {
        if (arr[start] !== '') break;
      }

      var end = arr.length - 1;
      for (; end >= 0; end--) {
        if (arr[end] !== '') break;
      }

      if (start > end) return [];
      return arr.slice(start, end - start + 1);
    }

    var fromParts = trim(from.split('/'));
    var toParts = trim(to.split('/'));

    var length = Math.min(fromParts.length, toParts.length);
    var samePartsLength = length;
    for (var i = 0; i < length; i++) {
      if (fromParts[i] !== toParts[i]) {
        samePartsLength = i;
        break;
      }
    }

    var outputParts = [];
    for (var i = samePartsLength; i < fromParts.length; i++) {
      outputParts.push('..');
    }

    outputParts = outputParts.concat(toParts.slice(samePartsLength));

    return outputParts.join('/');
  }

  function dirname(path) {
    var result = splitPath(path),
        root = result[0],
        dir = result[1];

    if (!root && !dir) {
      // No dirname whatsoever
      return '.';
    }

    if (dir) {
      // It has a dirname, strip trailing slash
      dir = dir.substr(0, dir.length - 1);
    }

    return root + dir;
  }

  function basename(path, ext) {
    var f = splitPath(path)[2];
    // TODO: make this comparison case-insensitive on windows?
    if (ext && f.substr(-1 * ext.length) === ext) {
      f = f.substr(0, f.length - ext.length);
    }
    return f;
  }

  function extname(path) {
    return splitPath(path)[3];
  }

  // NOTE: we don't support path.exists() or path.existsSync(), which are deprecated,
  // and need a FileSystem instance to work.  Use fs.stat().

  return {
    normalize: normalize,
    resolve: resolve,
    join: join,
    relative: relative,
    sep: '/',
    delimiter: ':',
    dirname: dirname,
    basename: basename,
    extname: extname
  };

});