'use strict';

const util = require('util');
const isWindows = process.platform === 'win32';

function assertPath(path) {
  if (typeof path !== 'string') {
    throw new TypeError('Path must be a string. Received ' +
                        util.inspect(path));
  }
}

// resolves . and .. elements in a path array with directory names there
// must be no slashes 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) {
  var res = [];
  for (var i = 0; i < parts.length; i++) {
    var p = parts[i];

    // ignore empty parts
    if (!p || p === '.')
      continue;

    if (p === '..') {
      if (res.length && res[res.length - 1] !== '..') {
        res.pop();
      } else if (allowAboveRoot) {
        res.push('..');
      }
    } else {
      res.push(p);
    }
  }

  return res;
}

// Returns an array with empty elements removed from either end of the input
// array or the original array if no elements need to be removed
function trimArray(arr) {
  var lastIndex = arr.length - 1;
  var start = 0;
  for (; start <= lastIndex; start++) {
    if (arr[start])
      break;
  }

  var end = lastIndex;
  for (; end >= 0; end--) {
    if (arr[end])
      break;
  }

  if (start === 0 && end === lastIndex)
    return arr;
  if (start > end)
    return [];
  return arr.slice(start, end + 1);
}

// Regex to split a windows path into three parts: [*, device, slash,
// tail] windows-only
const splitDeviceRe =
    /^([a-zA-Z]:|[\\\/]{2}[^\\\/]+[\\\/]+[^\\\/]+)?([\\\/])?([\s\S]*?)$/;

// Regex to split the tail part of the above into [*, dir, basename, ext]
const splitTailRe =
    /^([\s\S]*?)((?:\.{1,2}|[^\\\/]+?|)(\.[^.\/\\]*|))(?:[\\\/]*)$/;

var win32 = {};

// Function to split a filename into [root, dir, basename, ext]
function win32SplitPath(filename) {
  // Separate device+slash from tail
  var result = splitDeviceRe.exec(filename),
      device = (result[1] || '') + (result[2] || ''),
      tail = result[3];
  // Split the tail into dir, basename and extension
  var result2 = splitTailRe.exec(tail),
      dir = result2[1],
      basename = result2[2],
      ext = result2[3];
  return [device, dir, basename, ext];
}

function win32StatPath(path) {
  var result = splitDeviceRe.exec(path),
      device = result[1] || '',
      isUnc = !!device && device[1] !== ':';
  return {
    device,
    isUnc,
    isAbsolute: isUnc || !!result[2], // UNC paths are always absolute
    tail: result[3]
  };
}

function normalizeUNCRoot(device) {
  return '\\\\' + device.replace(/^[\\\/]+/, '').replace(/[\\\/]+/g, '\\');
}

// path.resolve([from ...], to)
win32.resolve = function() {
  var resolvedDevice = '',
      resolvedTail = '',
      resolvedAbsolute = false;

  for (var i = arguments.length - 1; i >= -1; i--) {
    var path;
    if (i >= 0) {
      path = arguments[i];
    } else if (!resolvedDevice) {
      path = process.cwd();
    } else {
      // Windows has the concept of drive-specific current working
      // directories. If we've resolved a drive letter but not yet an
      // absolute path, get cwd for that drive. We're sure the device is not
      // an unc path at this points, because unc paths are always absolute.
      path = process.env['=' + resolvedDevice];
      // Verify that a drive-local cwd was found and that it actually points
      // to our drive. If not, default to the drive's root.
      if (!path || path.substr(0, 3).toLowerCase() !==
          resolvedDevice.toLowerCase() + '\\') {
        path = resolvedDevice + '\\';
      }
    }

    assertPath(path);

    // Skip empty entries
    if (path === '') {
      continue;
    }

    var result = win32StatPath(path),
        device = result.device,
        isUnc = result.isUnc,
        isAbsolute = result.isAbsolute,
        tail = result.tail;

    if (device &&
        resolvedDevice &&
        device.toLowerCase() !== resolvedDevice.toLowerCase()) {
      // This path points to another device so it is not applicable
      continue;
    }

    if (!resolvedDevice) {
      resolvedDevice = device;
    }
    if (!resolvedAbsolute) {
      resolvedTail = tail + '\\' + resolvedTail;
      resolvedAbsolute = isAbsolute;
    }

    if (resolvedDevice && resolvedAbsolute) {
      break;
    }
  }

  // Convert slashes to backslashes when `resolvedDevice` points to an UNC
  // root. Also squash multiple slashes into a single one where appropriate.
  if (isUnc) {
    resolvedDevice = normalizeUNCRoot(resolvedDevice);
  }

  // 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 tail path
  resolvedTail = normalizeArray(resolvedTail.split(/[\\\/]+/),
                                !resolvedAbsolute).join('\\');

  return (resolvedDevice + (resolvedAbsolute ? '\\' : '') + resolvedTail) ||
         '.';
};


win32.normalize = function(path) {
  assertPath(path);

  var result = win32StatPath(path),
      device = result.device,
      isUnc = result.isUnc,
      isAbsolute = result.isAbsolute,
      tail = result.tail,
      trailingSlash = /[\\\/]$/.test(tail);

  // Normalize the tail path
  tail = normalizeArray(tail.split(/[\\\/]+/), !isAbsolute).join('\\');

  if (!tail && !isAbsolute) {
    tail = '.';
  }
  if (tail && trailingSlash) {
    tail += '\\';
  }

  // Convert slashes to backslashes when `device` points to an UNC root.
  // Also squash multiple slashes into a single one where appropriate.
  if (isUnc) {
    device = normalizeUNCRoot(device);
  }

  return device + (isAbsolute ? '\\' : '') + tail;
};


win32.isAbsolute = function(path) {
  assertPath(path);
  return win32StatPath(path).isAbsolute;
};

win32.join = function() {
  var paths = [];
  for (var i = 0; i < arguments.length; i++) {
    var arg = arguments[i];
    assertPath(arg);
    if (arg) {
      paths.push(arg);
    }
  }

  var joined = paths.join('\\');

  // Make sure that the joined path doesn't start with two slashes, because
  // normalize() will mistake it for an UNC path then.
  //
  // This step is skipped when it is very clear that the user actually
  // intended to point at an UNC path. This is assumed when the first
  // non-empty string arguments starts with exactly two slashes followed by
  // at least one more non-slash character.
  //
  // Note that for normalize() to treat a path as an UNC path it needs to
  // have at least 2 components, so we don't filter for that here.
  // This means that the user can use join to construct UNC paths from
  // a server name and a share name; for example:
  //   path.join('//server', 'share') -> '\\\\server\\share\')
  if (!/^[\\\/]{2}[^\\\/]/.test(paths[0])) {
    joined = joined.replace(/^[\\\/]{2,}/, '\\');
  }

  return win32.normalize(joined);
};


// path.relative(from, to)
// it will solve the relative path from 'from' to 'to', for instance:
// from = 'C:\\orandea\\test\\aaa'
// to = 'C:\\orandea\\impl\\bbb'
// The output of the function should be: '..\\..\\impl\\bbb'
win32.relative = function(from, to) {
  assertPath(from);
  assertPath(to);

  from = win32.resolve(from);
  to = win32.resolve(to);

  // windows is not case sensitive
  var lowerFrom = from.toLowerCase();
  var lowerTo = to.toLowerCase();

  var toParts = trimArray(to.split('\\'));

  var lowerFromParts = trimArray(lowerFrom.split('\\'));
  var lowerToParts = trimArray(lowerTo.split('\\'));

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

  if (samePartsLength === 0) {
    return to;
  }

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

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

  return outputParts.join('\\');
};


win32._makeLong = function(path) {
  // Note: this will *probably* throw somewhere.
  if (typeof path !== 'string')
    return path;

  if (!path) {
    return '';
  }

  var resolvedPath = win32.resolve(path);

  if (/^[a-zA-Z]\:\\/.test(resolvedPath)) {
    // path is local filesystem path, which needs to be converted
    // to long UNC path.
    return '\\\\?\\' + resolvedPath;
  } else if (/^\\\\[^?.]/.test(resolvedPath)) {
    // path is network UNC path, which needs to be converted
    // to long UNC path.
    return '\\\\?\\UNC\\' + resolvedPath.substring(2);
  }

  return path;
};


win32.dirname = function(path) {
  var result = win32SplitPath(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;
};


win32.basename = function(path, ext) {
  if (ext !== undefined && typeof ext !== 'string')
    throw new TypeError('"ext" argument must be a string');

  var f = win32SplitPath(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;
};


win32.extname = function(path) {
  return win32SplitPath(path)[3];
};


win32.format = function(pathObject) {
  if (pathObject === null || typeof pathObject !== 'object') {
    throw new TypeError(
        'Parameter "pathObject" must be an object, not ' + typeof pathObject
    );
  }

  var root = pathObject.root || '';

  if (typeof root !== 'string') {
    throw new TypeError(
        '"pathObject.root" must be a string or undefined, not ' +
        typeof pathObject.root
    );
  }

  var dir = pathObject.dir;
  var base = pathObject.base || '';
  if (!dir) {
    return base;
  }
  if (dir[dir.length - 1] === win32.sep) {
    return dir + base;
  }
  return dir + win32.sep + base;
};


win32.parse = function(pathString) {
  assertPath(pathString);

  var allParts = win32SplitPath(pathString);
  return {
    root: allParts[0],
    dir: allParts[0] + allParts[1].slice(0, -1),
    base: allParts[2],
    ext: allParts[3],
    name: allParts[2].slice(0, allParts[2].length - allParts[3].length)
  };
};


win32.sep = '\\';
win32.delimiter = ';';


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


function posixSplitPath(filename) {
  const out = splitPathRe.exec(filename);
  out.shift();
  return out;
}


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

  for (var i = arguments.length - 1; i >= -1 && !resolvedAbsolute; i--) {
    var path = (i >= 0) ? arguments[i] : process.cwd();

    assertPath(path);

    // Skip empty entries
    if (path === '') {
      continue;
    }

    resolvedPath = path + '/' + resolvedPath;
    resolvedAbsolute = path[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('/'),
                                !resolvedAbsolute).join('/');

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

// path.normalize(path)
// posix version
posix.normalize = function(path) {
  assertPath(path);

  var isAbsolute = posix.isAbsolute(path),
      trailingSlash = path && path[path.length - 1] === '/';

  // Normalize the path
  path = normalizeArray(path.split('/'), !isAbsolute).join('/');

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

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

// posix version
posix.isAbsolute = function(path) {
  assertPath(path);
  return !!path && path[0] === '/';
};

// posix version
posix.join = function() {
  var path = '';
  for (var i = 0; i < arguments.length; i++) {
    var segment = arguments[i];
    assertPath(segment);
    if (segment) {
      if (!path) {
        path += segment;
      } else {
        path += '/' + segment;
      }
    }
  }
  return posix.normalize(path);
};


// path.relative(from, to)
// posix version
posix.relative = function(from, to) {
  assertPath(from);
  assertPath(to);

  from = posix.resolve(from).substr(1);
  to = posix.resolve(to).substr(1);

  var fromParts = trimArray(from.split('/'));
  var toParts = trimArray(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('/');
};


posix._makeLong = function(path) {
  return path;
};


posix.dirname = function(path) {
  var result = posixSplitPath(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;
};


posix.basename = function(path, ext) {
  if (ext !== undefined && typeof ext !== 'string')
    throw new TypeError('"ext" argument must be a string');

  var f = posixSplitPath(path)[2];

  if (ext && f.substr(-1 * ext.length) === ext) {
    f = f.substr(0, f.length - ext.length);
  }
  return f;
};


posix.extname = function(path) {
  return posixSplitPath(path)[3];
};


posix.format = function(pathObject) {
  if (pathObject === null || typeof pathObject !== 'object') {
    throw new TypeError(
        'Parameter "pathObject" must be an object, not ' + typeof pathObject
    );
  }

  var root = pathObject.root || '';

  if (typeof root !== 'string') {
    throw new TypeError(
        '"pathObject.root" must be a string or undefined, not ' +
        typeof pathObject.root
    );
  }

  var dir = pathObject.dir ? pathObject.dir + posix.sep : '';
  var base = pathObject.base || '';
  return dir + base;
};


posix.parse = function(pathString) {
  assertPath(pathString);

  var allParts = posixSplitPath(pathString);
  return {
    root: allParts[0],
    dir: allParts[0] + allParts[1].slice(0, -1),
    base: allParts[2],
    ext: allParts[3],
    name: allParts[2].slice(0, allParts[2].length - allParts[3].length)
  };
};


posix.sep = '/';
posix.delimiter = ':';


if (isWindows)
  module.exports = win32;
else /* posix */
  module.exports = posix;

module.exports.posix = posix;
module.exports.win32 = win32;