/**
 * Implementation of server component.
 * Init and start server instance.
 */
var logger = require('pomelo-logger').getLogger('pomelo', __filename);
var fs = require('fs');
var path = require('path');
var pathUtil = require('../util/pathUtil');
var Loader = require('pomelo-loader');
var utils = require('../util/utils');
var schedule = require('pomelo-scheduler');
var events = require('../util/events');
var Constants = require('../util/constants');
var FilterService = require('../common/service/filterService');
var HandlerService = require('../common/service/handlerService');

var ST_INITED = 0;    // server inited
var ST_STARTED = 1;   // server started
var ST_STOPED = 2;    // server stoped

/**
 * Server factory function.
 *
 * @param {Object} app  current application context
 * @return {Object} erver instance
 */
module.exports.create = function(app, opts) {
  return new Server(app, opts);
};

var Server = function (app, opts) {
  this.opts = opts || {};
  this.app = app;
  this.globalFilterService = null;
  this.filterService = null;
  this.handlerService = null;
  this.crons = [];
  this.jobs = {};
  this.state = ST_INITED;

  app.event.on(events.ADD_CRONS, this.addCrons.bind(this));
  app.event.on(events.REMOVE_CRONS, this.removeCrons.bind(this));
};

var pro = Server.prototype;

/**
 * Server lifecycle callback
 */
pro.start = function() {
  if(this.state > ST_INITED) {
    return;
  }

  this.globalFilterService = initFilter(true, this.app);
  this.filterService = initFilter(false, this.app);
  this.handlerService = initHandler(this.app, this.opts);
  this.cronHandlers = loadCronHandlers(this.app);
  loadCrons(this, this.app);
  this.state = ST_STARTED;
};

pro.afterStart = function() {
  scheduleCrons(this, this.crons);
};

/**
 * Stop server
 */
pro.stop = function() {
  this.state = ST_STOPED;
};

/**
 * Global handler.
 *
 * @param  {Object} msg request message
 * @param  {Object} session session object
 * @param  {Callback} callback function 
 */
pro.globalHandle = function(msg, session, cb) {
  if(this.state !== ST_STARTED) {
    utils.invokeCallback(cb, new Error('server not started'));
    return;
  }

  var routeRecord = parseRoute(msg.route);
  if(!routeRecord) {
    utils.invokeCallback(cb, new Error('meet unknown route message %j', msg.route));
    return;
  }

  var self = this;
  var dispatch = function(err, resp, opts) {
    if(err) {
      handleError(true, self, err, msg, session, resp, opts, function(err, resp, opts) {
        response(true, self, err, msg, session, resp, opts, cb);
      });
      return;
    }

    if(self.app.getServerType() !== routeRecord.serverType) {
      doForward(self.app, msg, session, routeRecord, function(err, resp, opts) {
        response(true, self, err, msg, session, resp, opts, cb);
      });
    } else {
      doHandle(self, msg, session, routeRecord, function(err, resp, opts) {
        response(true, self, err, msg, session, resp, opts, cb);
      });
    }
  };
  beforeFilter(true, self, msg, session, dispatch);
};

/**
 * Handle request
 */
pro.handle = function(msg, session, cb) {
   if(this.state !== ST_STARTED) {
    cb(new Error('server not started'));
    return;
  }

  var routeRecord = parseRoute(msg.route);
  doHandle(this, msg, session, routeRecord, cb);
};

/**
 * Add crons at runtime.
 *
 * @param {Array} crons would be added in application
 */
pro.addCrons = function(crons) {
  this.cronHandlers = loadCronHandlers(this.app);
  for(var i=0, l=crons.length; i<l; i++) {
    var cron = crons[i];
    checkAndAdd(cron, this.crons, this);
  }
  scheduleCrons(this, crons);
};

/**
 * Remove crons at runtime.
 *
 * @param {Array} crons would be removed in application
 */
pro.removeCrons = function(crons) {
  for(var i=0, l=crons.length; i<l; i++) {
    var cron = crons[i];
    var id = parseInt(cron.id);
    if(!!this.jobs[id]) {
      schedule.cancelJob(this.jobs[id]);
    } else {
      logger.warn('cron is not in application: %j', cron);
    }
  }
};

var initFilter = function(isGlobal, app) {
  var service = new FilterService();
  var befores, afters;

  if(isGlobal) {
    befores = app.get(Constants.KEYWORDS.GLOBAL_BEFORE_FILTER);
    afters = app.get(Constants.KEYWORDS.GLOBAL_AFTER_FILTER);
  } else {
    befores = app.get(Constants.KEYWORDS.BEFORE_FILTER);
    afters = app.get(Constants.KEYWORDS.AFTER_FILTER);
  }

  var i, l;
  if(befores) {
    for(i=0, l=befores.length; i<l; i++) {
      service.before(befores[i]);
    }
  }

  if(afters) {
    for(i=0, l=afters.length; i<l; i++) {
      service.after(afters[i]);
    }
  }

  return service;
};

var initHandler = function(app, opts) {
  return new HandlerService(app, opts);
};

/**
 * Load cron handlers from current application
 */
var loadCronHandlers = function(app) {
  var p = pathUtil.getCronPath(app.getBase(), app.getServerType());
  if(p) {
    return Loader.load(p, app);
  }
};

/**
 * Load crons from configure file
 */
var loadCrons = function(server, app) {
  var env = app.get(Constants.RESERVED.ENV);
  var p = path.join(app.getBase(), Constants.FILEPATH.CRON);
  if(!fs.existsSync(p)) {
    p = path.join(app.getBase(), Constants.FILEPATH.CONFIG_DIR, env, path.basename(Constants.FILEPATH.CRON));
    if (!fs.existsSync(p)) {
      return;
    }
  }
  app.loadConfigBaseApp(Constants.RESERVED.CRONS, Constants.FILEPATH.CRON);
  var crons = app.get(Constants.RESERVED.CRONS);
  for(var serverType in crons) {
    if(app.serverType === serverType) {
      var list = crons[serverType];
      for(var i = 0; i<list.length; i++) {
        if(!list[i].serverId) {
          checkAndAdd(list[i], server.crons, server);
        } else {
          if(app.serverId === list[i].serverId) {
            checkAndAdd(list[i], server.crons, server);
          }
        }
      }
    }
  }
};

/**
 * Fire before filter chain if any
 */
var beforeFilter = function(isGlobal, server, msg, session, cb) {
  var fm;
  if(isGlobal) {
    fm = server.globalFilterService;
  } else {
    fm = server.filterService;
  }
  if(fm) {
    fm.beforeFilter(msg, session, cb);
  } else {
    utils.invokeCallback(cb);
  }
};

/**
 * Fire after filter chain if have
 */
var afterFilter = function(isGlobal, server, err, msg, session, resp, opts, cb) {
  var fm;
  if(isGlobal) {
    fm = server.globalFilterService;
  } else {
    fm = server.filterService;
  }
  if(fm) {
    if(isGlobal) {
      fm.afterFilter(err, msg, session, resp, function() {
        // do nothing
      });
    } else {
      fm.afterFilter(err, msg, session, resp, function(err) {
        cb(err, resp, opts);
      });
    }
  }
};

/**
 * pass err to the global error handler if specified
 */
var handleError = function(isGlobal, server, err, msg, session, resp, opts, cb) {
  var handler;
  if(isGlobal) {
    handler = server.app.get(Constants.RESERVED.GLOBAL_ERROR_HANDLER);
  } else {
    handler = server.app.get(Constants.RESERVED.ERROR_HANDLER);
  }
  if(!handler) {
    logger.debug('no default error handler to resolve unknown exception. ' + err.stack);
    utils.invokeCallback(cb, err, resp, opts);
  } else {
    if(handler.length === 5) {
      handler(err, msg, resp, session, cb);
    } else {
       handler(err, msg, resp, session, opts, cb);     
    }
  }
};

/**
 * Send response to client and fire after filter chain if any.
 */

var response = function(isGlobal, server, err, msg, session, resp, opts, cb) {
  if(isGlobal) {
    cb(err, resp, opts);
    // after filter should not interfere response
    afterFilter(isGlobal, server, err, msg, session, resp, opts, cb);
  } else {
    afterFilter(isGlobal, server, err, msg, session, resp, opts, cb);
  }
};

/**
 * Parse route string.
 *
 * @param  {String} route route string, such as: serverName.handlerName.methodName
 * @return {Object}       parse result object or null for illeagle route string
 */
var parseRoute = function(route) {
  if(!route) {
    return null;
  }
  var ts = route.split('.');
  if(ts.length !== 3) {
    return null;
  }

  return {
    route: route,
    serverType: ts[0],
    handler: ts[1],
    method: ts[2]
  };
};

var doForward = function(app, msg, session, routeRecord, cb) {
  var finished = false;
  //should route to other servers
  try {
    app.sysrpc[routeRecord.serverType].msgRemote.forwardMessage(
      session,
      msg,
      session.export(),
      function(err, resp, opts) {
        if(err) {
          logger.error('fail to process remote message:' + err.stack);
        }
        finished = true;
        utils.invokeCallback(cb, err, resp, opts);
      }
    );
  } catch(err) {
    if(!finished) {
      logger.error('fail to forward message:' + err.stack);
      utils.invokeCallback(cb, err);
    }
  }
};

var doHandle = function(server, msg, session, routeRecord, cb) {
  var originMsg = msg;
  msg = msg.body || {};
  msg.__route__ = originMsg.route;

  var self = server;

  var handle = function(err, resp, opts) {
    if(err) {
      // error from before filter
      handleError(false, self, err, msg, session, resp, opts, function(err, resp, opts) {
        response(false, self, err, msg, session, resp, opts, cb);
      });
      return;
    }

    self.handlerService.handle(routeRecord, msg, session, function(err, resp, opts) {
      if(err) {
        //error from handler
        handleError(false, self, err, msg, session, resp, opts, function(err, resp, opts) {
          response(false, self, err, msg, session, resp, opts, cb);
        });
        return;
      }

      response(false, self, err, msg, session, resp, opts, cb);
    });
  };  //end of handle

  beforeFilter(false, server, msg, session, handle);
};

/**
 * Schedule crons
 */
var scheduleCrons = function(server, crons) {
  var handlers = server.cronHandlers;
  for(var i = 0; i<crons.length; i++) {
    var cronInfo = crons[i];
    var time = cronInfo.time;
    var action = cronInfo.action;
    var jobId = cronInfo.id;

    if(!time || !action || !jobId) {
      logger.error('cron miss necessary parameters: %j', cronInfo);
      continue;
    }

    if(action.indexOf('.') < 0) {
      logger.error('cron action is error format: %j', cronInfo);
      continue;
    }
    
    var cron = action.split('.')[0];
    var job = action.split('.')[1];
    var handler = handlers[cron];
    
    if(!handler) {
      logger.error('could not find cron: %j', cronInfo);
      continue;
    }
      
    if(typeof handler[job] !== 'function') {
      logger.error('could not find cron job: %j, %s', cronInfo, job);
      continue;
    }
      
    var id = schedule.scheduleJob(time, handler[job].bind(handler));
    server.jobs[jobId] = id;
  }
};

/**
 * If cron is not in crons then put it in the array.
 */
var checkAndAdd = function(cron, crons, server) {
  if(!containCron(cron.id, crons)) {
    server.crons.push(cron);
  } else {
    logger.warn('cron is duplicated: %j', cron);
  }
};

/**
 * Check if cron is in crons.
 */
var containCron = function(id, crons) {
  for(var i=0, l=crons.length; i<l; i++) {
    if(id === crons[i].id) {
      return true;
    }
  }
  return false;
};