const EXPORTED_SYMBOLS=["AsyncBatch"];

function AsyncBatch(parentBatch, name, onErrorCallback)
{
  if (parentBatch && !(parentBatch instanceof AsyncBatch))
    throw new Error(parentBatch+" is not instance of AsyncBatch");
  if (!name)
    throw new Error("Unnamed batches are disallowed.");
  let _steps = [];
  let _onError = onErrorCallback;
  let _name=name;
  let _isRunning = false
  Object.defineProperty(this,"steps",{get: function(){ return _steps; }});
  Object.defineProperty(this,"step",{get: function(){ return this._step.bind(this); }});
  Object.defineProperty(this, "name", {get: function() { return _name; }});
  Object.defineProperty(this,"parent", {get: function(){ return parentBatch; }});
  Object.defineProperty(this, "onError", {get: function(){ return _onError; }});
  Object.defineProperty(this, "isRunning", {get: function(){ return _isRunning; }, set: function(value){ _isRunning = value; }});
}

AsyncBatch.prototype = 
{
  childBatch: function(name)
  {
    return new AsyncBatch(this, name, null);
  },
  
  toString: function()
  {
    let names=[];
    let parent=this;
    while(parent)
    {
      names.unshift(parent.name);
      parent=parent.parent;
    }
    return "[AsyncBatch."+names.join(".")+"]";
  },
  
  addSteps: function(stepsArray, thisObj)
  {
    stepsArray.forEach((function(elem)
    {
      this.steps.push({func: elem, thisObj: thisObj});
    }).bind(this));
  },
  
  safeCall: function(step, args)
  {
    try
    {
      if (typeof(step.thisObj) == "object")
        step.func.apply(step.thisObj, args);
      else
        step.func(args);
    }
    catch(err)
    {
      if (typeof(step.thisObj) == "object")
        Components.utils.reportError(step.thisObj+" on AsyncBatch.safeCall: "+err.message);
      else
        Components.utils.reportError("AsyncBatch.safeCall: "+err.message);
      let parent = this;
      while(parent)
      {
        if (parent.onError)
          parent.onError.apply(step.thisObj, [err])
        parent = parent.parent;
      }
    }
  },
  
  get root()
  {
    let parent = this;
    while(parent.parent)
      parent = parent.parent;
    return parent;
  },
  
  _step: function()
  {
    if (!this.isRunning)
    {
      if (this.steps.length==0)
        throw new Error("Empty batches are disallowed.");
      if (!this.onError && !this.parent)
        throw new Error("Root batch must have an onError handler.");
      this.isRunning = true;
    }
    if (this.steps.length==0)
    {
      if (this.parent)
        this.parent.step.apply(null, Array.prototype.slice.call(arguments));
      return;
    }
    this.safeCall(this.steps.shift(), Array.prototype.slice.call(arguments));
  },
  
  clear: function()
  {
    while (this.steps.length>0)
      this.steps.pop();
  }
};

let batch = new AsyncBatch(null, "updateToVer2", this.handleError);
batch.addSteps([function()
{
  fpcln.backupDB(1, batch.step);                                                                }, function(aStatus) {
  
  if (!Components.isSuccessCode(aStatus))
    throw new Error("dbwrapper.updateToVer2: Database file backup creation error.");
  this.applyScripts(scripts, batch.step);                                                       }, function() {
  
  fpcln.getAddonsChrome(batch.step);                                                             }, function(chromes) {
  
  let stmt=this.buildStatement("update installed_addons set chrome=[:chrome] where ext_id=[:id]", chromes);
  this.executeStatement(stmt, batch.step);                                                       }, function() {
  
  .................
}], this);
batch.step();

fixBrokenDRI: function(parentBatch)
{
  var batch = parentBatch.childBatch("fixBrokenDRI");
  batch.addSteps([function() {
    var stmt = this.mDBConn.createStatement("select id, table_name, column_name from v$broken_links");
    this.executeStatement(stmt, batch.step);                                                      }, function(results) {
    
    ..................
    var stmts=[];
    ...................
    this.executeStatementsArray(stmts, batch.step);
  }], this);
  batch.step();
},