/*jslint newcap: true */
/*global XMLHttpRequest: false, FormData: false */
/*
 * Inline Text Attachment
 *
 * Author: Roy van Kaathoven
 * Contact: ik@royvankaathoven.nl
 */
(function(document, window) {
  'use strict';

  var inlineAttachment = function(options, instance) {
    this.settings = inlineAttachment.util.merge(options, inlineAttachment.defaults);
    this.editor = instance;
    this.filenameTag = '{filename}';
    this.lastValue = null;
  };

  /**
   * Will holds the available editors
   *
   * @type {Object}
   */
  inlineAttachment.editors = {};

  /**
   * Utility functions
   */
  inlineAttachment.util = {

    /**
     * Simple function to merge the given objects
     *
     * @param {Object[]} object Multiple object parameters
     * @returns {Object}
     */
    merge: function() {
      var result = {};
      for (var i = arguments.length - 1; i >= 0; i--) {
        var obj = arguments[i];
        for (var k in obj) {
          if (obj.hasOwnProperty(k)) {
            result[k] = obj[k];
          }
        }
      }
      return result;
    },

    /**
     * Append a line of text at the bottom, ensuring there aren't unnecessary newlines
     *
     * @param {String} appended Current content
     * @param {String} previous Value which should be appended after the current content
     */
    appendInItsOwnLine: function(previous, appended) {
      return (previous + "\n\n[[D]]" + appended)
        .replace(/(\n{2,})\[\[D\]\]/, "\n\n")
        .replace(/^(\n*)/, "");
    },

    /**
     * Inserts the given value at the current cursor position of the textarea element
     *
     * @param  {HtmlElement} el
     * @param  {String} value Text which will be inserted at the cursor position
     */
    insertTextAtCursor: function(el, text) {
      var scrollPos = el.scrollTop,
        strPos = 0,
        browser = false,
        range;

      if ((el.selectionStart || el.selectionStart === '0')) {
        browser = "ff";
      } else if (document.selection) {
        browser = "ie";
      }

      if (browser === "ie") {
        el.focus();
        range = document.selection.createRange();
        range.moveStart('character', -el.value.length);
        strPos = range.text.length;
      } else if (browser === "ff") {
        strPos = el.selectionStart;
      }

      var front = (el.value).substring(0, strPos);
      var back = (el.value).substring(strPos, el.value.length);
      el.value = front + text + back;
      strPos = strPos + text.length;
      if (browser === "ie") {
        el.focus();
        range = document.selection.createRange();
        range.moveStart('character', -el.value.length);
        range.moveStart('character', strPos);
        range.moveEnd('character', 0);
        range.select();
      } else if (browser === "ff") {
        el.selectionStart = strPos;
        el.selectionEnd = strPos;
        el.focus();
      }
      el.scrollTop = scrollPos;
    }
  };

  /**
   * Default configuration options
   *
   * @type {Object}
   */
  inlineAttachment.defaults = {
    /**
     * URL where the file will be send
     */
    uploadUrl: 'uploadimage',

    /**
     * Which method will be used to send the file to the upload URL
     */
    uploadMethod: 'POST',

    /**
     * Name in which the file will be placed
     */
    uploadFieldName: 'image',

    /**
     * Extension which will be used when a file extension could not
     * be detected
     */
    defualtExtension: 'png',

    /**
     * JSON field which refers to the uploaded file URL
     */
    jsonFieldName: 'link',

    /**
     * Allowed MIME types
     */
    allowedTypes: [
      'image/jpeg',
      'image/png',
      'image/jpg',
      'image/gif'
    ],

    /**
     * Text which will be inserted when dropping or pasting a file.
     * Acts as a placeholder which will be replaced when the file is done with uploading
     */
    progressText: '![Uploading file...{filename}]()',

    /**
     * When a file has successfully been uploaded the progressText
     * will be replaced by the urlText, the {filename} tag will be replaced
     * by the filename that has been returned by the server
     */
    urlText: "![]({filename})",

    /**
     * Text which will be used when uploading has failed
     */
    errorText: "Error uploading file",

    /**
     * Extra parameters which will be send when uploading a file
     */
    extraParams: {},

    /**
     * Extra headers which will be send when uploading a file
     */
    extraHeaders: {},

    /**
     * Before the file is send
     */
    beforeFileUpload: function() {
      return true;
    },

    /**
     * Triggers when a file is dropped or pasted
     */
    onFileReceived: function() {},

    /**
     * Custom upload handler
     *
     * @return {Boolean} when false is returned it will prevent default upload behavior
     */
    onFileUploadResponse: function() {
      return true;
    },

    /**
     * Custom error handler. Runs after removing the placeholder text and before the alert().
     * Return false from this function to prevent the alert dialog.
     *
     * @return {Boolean} when false is returned it will prevent default error behavior
     */
    onFileUploadError: function() {
      return true;
    },

    /**
     * When a file has succesfully been uploaded
     */
    onFileUploaded: function() {}
  };

  /**
   * Uploads the blob
   *
   * @param  {Blob} file blob data received from event.dataTransfer object
   * @return {XMLHttpRequest} request object which sends the file
   */
  inlineAttachment.prototype.uploadFile = function(file, id) {
    var me = this,
      formData = new FormData(),
      xhr = new XMLHttpRequest(),
      id = id,
      settings = this.settings,
      extension = settings.defualtExtension;

    if (typeof settings.setupFormData === 'function') {
      settings.setupFormData(formData, file);
    }

    // Attach the file. If coming from clipboard, add a default filename (only works in Chrome for now)
    // http://stackoverflow.com/questions/6664967/how-to-give-a-blob-uploaded-as-formdata-a-file-name
    if (file.name) {
      var fileNameMatches = file.name.match(/\.(.+)$/);
      if (fileNameMatches) {
        extension = fileNameMatches[1];
      }
    }

    var remoteFilename = "image-" + Date.now() + "." + extension;
    if (typeof settings.remoteFilename === 'function') {
      remoteFilename = settings.remoteFilename(file);
    }

    formData.append(settings.uploadFieldName, file, remoteFilename);

    // Append the extra parameters to the formdata
    if (typeof settings.extraParams === "object") {
      for (var key in settings.extraParams) {
        if (settings.extraParams.hasOwnProperty(key)) {
          formData.append(key, settings.extraParams[key]);
        }
      }
    }

    xhr.open('POST', settings.uploadUrl);

    // Add any available extra headers
    if (typeof settings.extraHeaders === "object") {
        for (var header in settings.extraHeaders) {
            if (settings.extraHeaders.hasOwnProperty(header)) {
                xhr.setRequestHeader(header, settings.extraHeaders[header]);
            }
        }
    }

    xhr.onload = function() {
      // If HTTP status is OK or Created
      if (xhr.status === 200 || xhr.status === 201) {
        me.onFileUploadResponse(xhr, id);
      } else {
        me.onFileUploadError(xhr, id);
      }
    };
    if (settings.beforeFileUpload(xhr) !== false) {
      xhr.send(formData);
    }
    return xhr;
  };

  /**
   * Returns if the given file is allowed to handle
   *
   * @param {File} clipboard data file
   */
  inlineAttachment.prototype.isFileAllowed = function(file) {
    if (this.settings.allowedTypes.indexOf('*') === 0){
      return true;
    } else {
      return this.settings.allowedTypes.indexOf(file.type) >= 0;
    }
  };

  /**
   * Handles upload response
   *
   * @param  {XMLHttpRequest} xhr
   * @return {Void}
   */
  inlineAttachment.prototype.onFileUploadResponse = function(xhr, id) {
    if (this.settings.onFileUploadResponse.call(this, xhr) !== false) {
      var result = JSON.parse(xhr.responseText),
        filename = result[this.settings.jsonFieldName];
        
      if (result && filename) {
          var replacements = [];
          var string = this.settings.progressText.replace(this.filenameTag, id);
          var lines = this.editor.getValue().split('\n');
        var newValue = this.settings.urlText.replace(this.filenameTag, filename);
          for(var i = 0; i < lines.length; i++) {
            var ch = lines[i].indexOf(string);
            if(ch != -1)
                replacements.push({replacement:newValue, from:{line:i, ch:ch}, to:{line:i, ch:ch + string.length}});
        }
          for(var i = 0; i < replacements.length; i++)
            this.editor.replaceRange(replacements[i]);
      }
    }
  };


  /**
   * Called when a file has failed to upload
   *
   * @param  {XMLHttpRequest} xhr
   * @return {Void}
   */
  inlineAttachment.prototype.onFileUploadError = function(xhr, id) {
    if (this.settings.onFileUploadError.call(this, xhr) !== false) {
      var replacements = [];
      var string = this.settings.progressText.replace(this.filenameTag, id);
      var lines = this.editor.getValue().split('\n');
        for(var i = 0; i < lines.length; i++) {
            var ch = lines[i].indexOf(this.lastValue);
            if(ch != -1)
                replacements.push({replacement:"", from:{line:i, ch:ch}, to:{line:i, ch:ch + string.length}});
        }
        for(var i = 0; i < replacements.length; i++)
            this.editor.replaceRange(replacements[i]);
    }
  };

  /**
   * Called when a file has been inserted, either by drop or paste
   *
   * @param  {File} file
   * @return {Void}
   */
  inlineAttachment.prototype.onFileInserted = function(file, id) {
    if (this.settings.onFileReceived.call(this, file) !== false) {
      this.lastValue = this.settings.progressText.replace(this.filenameTag, id);
      this.editor.insertValue(this.lastValue + "\n");
    }
  };


  /**
   * Called when a paste event occured
   * @param  {Event} e
   * @return {Boolean} if the event was handled
   */
  inlineAttachment.prototype.onPaste = function(e) {
    var result = false,
      clipboardData = e.clipboardData,
      items;

    if (typeof clipboardData === "object") {
      items = clipboardData.items || clipboardData.files || [];

      for (var i = 0; i < items.length; i++) {
        var item = items[i];
        if (this.isFileAllowed(item)) {
          result = true;
          var id = ID();
          this.onFileInserted(item.getAsFile(), id);
          this.uploadFile(item.getAsFile(), id);
        }
      }
    }

    if (result) { e.preventDefault(); }

    return result;
  };

  /**
   * Called when a drop event occures
   * @param  {Event} e
   * @return {Boolean} if the event was handled
   */
  inlineAttachment.prototype.onDrop = function(e) {
    var result = false;
    for (var i = 0; i < e.dataTransfer.files.length; i++) {
      var file = e.dataTransfer.files[i];
      if (this.isFileAllowed(file)) {
        result = true;
        var id = ID();
        this.onFileInserted(file, id);
        this.uploadFile(file, id);
      }
    }

    return result;
  };

  window.inlineAttachment = inlineAttachment;

})(document, window);

// Generate unique IDs for use as pseudo-private/protected names.
// Similar in concept to
// <http://wiki.ecmascript.org/doku.php?id=strawman:names>.
//
// The goals of this function are twofold:
// 
// * Provide a way to generate a string guaranteed to be unique when compared
//   to other strings generated by this function.
// * Make the string complex enough that it is highly unlikely to be
//   accidentally duplicated by hand (this is key if you're using `ID`
//   as a private/protected name on an object).
//
// Use:
//
//     var privateName = ID();
//     var o = { 'public': 'foo' };
//     o[privateName] = 'bar';
var ID = function () {
  // Math.random should be unique because of its seeding algorithm.
  // Convert it to base 36 (numbers + letters), and grab the first 9 characters
  // after the decimal.
  return '_' + Math.random().toString(36).substr(2, 9);
};