/**
 * The Pad Manager is a Factory for pad Objects
 */

/*
 * 2011 Peter 'Pita' Martischka (Primary Technology Ltd)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS-IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

var ERR = require("async-stacktrace");
var customError = require("../utils/customError");
var Pad = require("../db/Pad").Pad;
var db = require("./DB").db;

/** 
 * An Object containing all known Pads. Provides "get" and "set" functions,
 * which should be used instead of indexing with brackets. These prepend a
 * colon to the key, to avoid conflicting with built-in Object methods or with
 * these functions themselves.
 *
 * If this is needed in other places, it would be wise to make this a prototype
 * that's defined somewhere more sensible.
 */
var globalPads = {
    get: function (name) { return this[':'+name]; },
    set: function (name, value) { this[':'+name] = value; },
    remove: function (name) { delete this[':'+name]; }
};

/**
 * An array of padId transformations. These represent changes in pad name policy over
 * time, and allow us to "play back" these changes so legacy padIds can be found.
 */
var padIdTransforms = [
  [/\s+/g, '_'],
  [/:+/g, '_']
];

/**
 * Returns a Pad Object with the callback
 * @param id A String with the id of the pad
 * @param {Function} callback 
 */
exports.getPad = function(id, text, callback)
{    
  //check if this is a valid padId
  if(!exports.isValidPadId(id))
  {
    callback(new customError(id + " is not a valid padId","apierror"));
    return;
  }
  
  //make text an optional parameter
  if(typeof text == "function")
  {
    callback = text;
    text = null;
  }
  
  //check if this is a valid text
  if(text != null)
  {
    //check if text is a string
    if(typeof text != "string")
    {
      callback(new customError("text is not a string","apierror"));
      return;
    }
    
    //check if text is less than 100k chars
    if(text.length > 100000)
    {
      callback(new customError("text must be less than 100k chars","apierror"));
      return;
    }
  }
  
  var pad = globalPads.get(id);
  
  //return pad if its already loaded
  if(pad != null)
  {
    callback(null, pad);
  }
  //try to load pad
  else
  {
    pad = new Pad(id);
    
    //initalize the pad
    pad.init(text, function(err)
    {
      if(ERR(err, callback)) return;
      
      globalPads.set(id, pad);
      callback(null, pad);
    });
  }
}

//checks if a pad exists
exports.doesPadExists = function(padId, callback)
{
  db.get("pad:"+padId, function(err, value)
  {
    if(ERR(err, callback)) return;
    callback(null, value != null);  
  });
}

//returns a sanitized padId, respecting legacy pad id formats
exports.sanitizePadId = function(padId, callback) {
  var transform_index = arguments[2] || 0;
  //we're out of possible transformations, so just return it
  if(transform_index >= padIdTransforms.length)
  {
    callback(padId);
  }
  //check if padId exists
  else
  {
    exports.doesPadExists(padId, function(junk, exists)
    {
      if(exists)
      {
        callback(padId);
      }
      else
      {
        //get the next transformation *that's different*
        var transformedPadId = padId;
        while(transformedPadId == padId && transform_index < padIdTransforms.length)
        {
          transformedPadId = padId.replace(padIdTransforms[transform_index][0], padIdTransforms[transform_index][1]);
          transform_index += 1;
        }
        //check the next transform
        exports.sanitizePadId(transformedPadId, callback, transform_index);
      }
    });
  }
}

exports.isValidPadId = function(padId)
{
  return /^(g.[a-zA-Z0-9]{16}\$)?[^$]{1,50}$/.test(padId);
}

//removes a pad from the array
exports.unloadPad = function(padId)
{
  if(globalPads.get(padId))
    globalPads.remove(padId);
}