'use strict';

var path = require('path');
var replace = require('replace-ext');
var buffer = require('is-buffer');

module.exports = VFile;

var own = {}.hasOwnProperty;
var proto = VFile.prototype;

proto.toString = toString;

/* Order of setting (least specific to most), we need this because
 * otherwise `{stem: 'a', path: '~/b.js'}` would throw, as a path
 * is needed before a stem can be set. */
var order = [
  'history',
  'path',
  'basename',
  'stem',
  'extname',
  'dirname'
];

/* Construct a new file. */
function VFile(options) {
  var prop;
  var index;
  var length;

  if (!options) {
    options = {};
  } else if (typeof options === 'string' || buffer(options)) {
    options = {contents: options};
  } else if ('message' in options && 'messages' in options) {
    return options;
  }

  if (!(this instanceof VFile)) {
    return new VFile(options);
  }

  this.data = {};
  this.messages = [];
  this.history = [];
  this.cwd = process.cwd();

  /* Set path related properties in the correct order. */
  index = -1;
  length = order.length;

  while (++index < length) {
    prop = order[index];

    if (own.call(options, prop)) {
      this[prop] = options[prop];
    }
  }

  /* Set non-path related properties. */
  for (prop in options) {
    if (order.indexOf(prop) === -1) {
      this[prop] = options[prop];
    }
  }
}

/* Access full path (`~/index.min.js`). */
Object.defineProperty(proto, 'path', {
  get: function () {
    return this.history[this.history.length - 1];
  },
  set: function (path) {
    assertNonEmpty(path, 'path');

    if (path !== this.path) {
      this.history.push(path);
    }
  }
});

/* Access parent path (`~`). */
Object.defineProperty(proto, 'dirname', {
  get: function () {
    return typeof this.path === 'string' ? path.dirname(this.path) : undefined;
  },
  set: function (dirname) {
    assertPath(this.path, 'dirname');
    this.path = path.join(dirname || '', this.basename);
  }
});

/* Access basename (`index.min.js`). */
Object.defineProperty(proto, 'basename', {
  get: function () {
    return typeof this.path === 'string' ? path.basename(this.path) : undefined;
  },
  set: function (basename) {
    assertNonEmpty(basename, 'basename');
    assertPart(basename, 'basename');
    this.path = path.join(this.dirname || '', basename);
  }
});

/* Access extname (`.js`). */
Object.defineProperty(proto, 'extname', {
  get: function () {
    return typeof this.path === 'string' ? path.extname(this.path) : undefined;
  },
  set: function (extname) {
    var ext = extname || '';

    assertPart(ext, 'extname');
    assertPath(this.path, 'extname');

    if (ext) {
      if (ext.charAt(0) !== '.') {
        throw new Error('`extname` must start with `.`');
      }

      if (ext.indexOf('.', 1) !== -1) {
        throw new Error('`extname` cannot contain multiple dots');
      }
    }

    this.path = replace(this.path, ext);
  }
});

/* Access stem (`index.min`). */
Object.defineProperty(proto, 'stem', {
  get: function () {
    return typeof this.path === 'string' ? path.basename(this.path, this.extname) : undefined;
  },
  set: function (stem) {
    assertNonEmpty(stem, 'stem');
    assertPart(stem, 'stem');
    this.path = path.join(this.dirname || '', stem + (this.extname || ''));
  }
});

/* Get the value of the file. */
function toString(encoding) {
  var value = this.contents || '';
  return buffer(value) ? value.toString(encoding) : String(value);
}

/* Assert that `part` is not a path (i.e., does
 * not contain `path.sep`). */
function assertPart(part, name) {
  if (part.indexOf(path.sep) !== -1) {
    throw new Error('`' + name + '` cannot be a path: did not expect `' + path.sep + '`');
  }
}

/* Assert that `part` is not empty. */
function assertNonEmpty(part, name) {
  if (!part) {
    throw new Error('`' + name + '` cannot be empty');
  }
}

/* Assert `path` exists. */
function assertPath(path, name) {
  if (!path) {
    throw new Error('Setting `' + name + '` requires `path` to be set too');
  }
}