/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

function utf16to8(str) {
    var out, i, len, c;

    out = "";
    len = str.length;
    for(i = 0; i < len; i++) 
    { 
        c = str.charCodeAt(i);   
        if ((c >= 0x0001) && (c <= 0x007F))
        {
            out += str.charAt(i);
        }
        else if (c > 0x07FF)
        {
            out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
            out += String.fromCharCode(0x80 | ((c >>  6) & 0x3F));
            out += String.fromCharCode(0x80 | ((c >>  0) & 0x3F));
        } 
        else
        {
            out += String.fromCharCode(0xC0 | ((c >>  6) & 0x1F));
            out += String.fromCharCode(0x80 | ((c >>  0) & 0x3F));
        }
    }
    return out;
}

function utf8to16(str) {
     var out, i, len, c;
     var char2, char3;

     out = "";
     len = str.length;
     i = 0;
     while(i < len) {   c = str.charCodeAt(i++);   switch(c >> 4)
  {
    case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
      // 0xxxxxxx
      out += str.charAt(i-1);
      break;
    case 12: case 13:
      // 110x xxxx   10xx xxxx
      char2 = str.charCodeAt(i++);
      out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
      break;
    case 14:
      // 1110 xxxx  10xx xxxx  10xx xxxx
      char2 = str.charCodeAt(i++);
      char3 = str.charCodeAt(i++);
      out += String.fromCharCode(((c & 0x0F) << 12) |
         ((char2 & 0x3F) << 6) |
         ((char3 & 0x3F) << 0));
      break;
  }
     }

     return out;
 }

var dump = function(msg) {
  log(msg);
};

/* General utilities used throughout devtools. */

/**
 * Turn the error |aError| into a string, without fail.
 */
this.safeErrorString = function safeErrorString(aError) {
  try {
    let errorString = aError.toString();
    if (typeof errorString === "string") {
      // Attempt to attach a stack to |errorString|. If it throws an error, or
      // isn't a string, don't use it.
      try {
        if (aError.stack) {
          let stack = aError.stack.toString();
          if (typeof stack === "string") {
            errorString += "\nStack: " + stack;
          }
        }
      } catch (ee) { }

      return errorString;
    }
  } catch (ee) { }

  return "<failed trying to find error description>";
}


/**
 * Report that |aWho| threw an exception, |aException|.
 */
this.reportException = function reportException(aWho, aException) {
  let msg = aWho + " threw an exception: " + safeErrorString(aException);

  dump(msg + "\n");

  // if (Components.utils.reportError) {
  //   /*
  //    * Note that the xpcshell test harness registers an observer for
  //    * console messages, so when we're running tests, this will cause
  //    * the test to quit.
  //    */
  //   Components.utils.reportError(msg);
  // }
}

/**
 * Given a handler function that may throw, return an infallible handler
 * function that calls the fallible handler, and logs any exceptions it
 * throws.
 *
 * @param aHandler function
 *      A handler function, which may throw.
 * @param aName string
 *      A name for aHandler, for use in error messages. If omitted, we use
 *      aHandler.name.
 *
 * (SpiderMonkey does generate good names for anonymous functions, but we
 * don't have a way to get at them from JavaScript at the moment.)
 */
this.makeInfallible = function makeInfallible(aHandler, aName) {
  if (!aName)
    aName = aHandler.name;

  return function (/* arguments */) {
    try {
      return aHandler.apply(this, arguments);
    } catch (ex) {
      let who = "Handler function";
      if (aName) {
        who += " " + aName;
      }
      reportException(who, ex);
    }
  }
}

const executeSoon = aFn => {
  Services.tm.mainThread.dispatch({
    run: this.makeInfallible(aFn)
  }, Components.interfaces.nsIThread.DISPATCH_NORMAL);
}

/**
 * Like Array.prototype.forEach, but doesn't cause jankiness when iterating over
 * very large arrays by yielding to the browser and continuing execution on the
 * next tick.
 *
 * @param Array aArray
 *        The array being iterated over.
 * @param Function aFn
 *        The function called on each item in the array.
 * @returns Promise
 *          A promise that is resolved once the whole array has been iterated
 *          over.
 */
this.yieldingEach = function yieldingEach(aArray, aFn) {
  const deferred = promise.defer();

  let i = 0;
  let len = aArray.length;

  (function loop() {
    const start = Date.now();

    while (i < len) {
      // Don't block the main thread for longer than 16 ms at a time. To
      // maintain 60fps, you have to render every frame in at least 16ms; we
      // aren't including time spent in non-JS here, but this is Good
      // Enough(tm).
      if (Date.now() - start > 16) {
        executeSoon(loop);
        return;
      }

      try {
        aFn(aArray[i++]);
      } catch (e) {
        deferred.reject(e);
        return;
      }
    }

    deferred.resolve();
  }());

  return deferred.promise;
}


/**
 * Like XPCOMUtils.defineLazyGetter, but with a |this| sensitive getter that
 * allows the lazy getter to be defined on a prototype and work correctly with
 * instances.
 *
 * @param Object aObject
 *        The prototype object to define the lazy getter on.
 * @param String aKey
 *        The key to define the lazy getter on.
 * @param Function aCallback
 *        The callback that will be called to determine the value. Will be
 *        called with the |this| value of the current instance.
 */
this.defineLazyPrototypeGetter =
function defineLazyPrototypeGetter(aObject, aKey, aCallback) {
  Object.defineProperty(aObject, aKey, {
    configurable: true,
    get: function() {
      const value = aCallback.call(this);

      Object.defineProperty(this, aKey, {
        configurable: true,
        writable: true,
        value: value
      });

      return value;
    }
  });
}