var step = require('step');
var PSQL = require('cartodb-psql');
var assert = require('assert');

function PostgresFormat(id) {
    this.id = id;
}

PostgresFormat.prototype = {

  getQuery: function(sql/*, options*/) {
    return sql;
  },

  getContentType: function(){
    return this._contentType;
  },

  getFileExtension: function() {
    return this.id;
  }

};

PostgresFormat.prototype.handleQueryRow = function(row, result) {
    result.addRow(row);
};

PostgresFormat.prototype.handleQueryRowWithSkipFields = function(row, result) {
    var sf = this.opts.skipfields;
    for ( var j=0; j<sf.length; ++j ) {
        delete row[sf[j]];
    }
    this.handleQueryRow(row, result);
};

PostgresFormat.prototype.handleNotice = function(msg, result) {
    if ( ! result.notices ) {
        result.notices = [];
    }
    for (var i=0; i<msg.length; i++) {
        result.notices.push(msg[i]);
    }
};

PostgresFormat.prototype.handleQueryEnd = function(result) {
  this.queryCanceller = undefined;

  if ( this.error ) {
    this.callback(this.error);
    return;
  }

  if ( this.opts.profiler ) {
      this.opts.profiler.done('gotRows');
  }

  this.opts.total_time = (Date.now() - this.start_time)/1000;

  // Drop field description for skipped fields
  if (this.hasSkipFields) {
    var sf = this.opts.skipfields;
    var newfields = [];
    for ( var j=0; j<result.fields.length; ++j ) {
      var f = result.fields[j];
      if ( sf.indexOf(f.name) === -1 ) {
          newfields.push(f);
      }
    }
    result.fields = newfields;
  }

  var that = this;

  step (
    function packageResult() {
      if ( that.opts.abortChecker ) {
        that.opts.abortChecker('packageResult');
      }
      that.transform(result, that.opts, this);
    },
    function sendResults(err, out){

        assert.ifError(err);

        // return to browser
        if ( out ) {
          if ( that.opts.beforeSink ) {
              that.opts.beforeSink();
          }
          that.opts.sink.send(out);
        } else {
          console.error("No output from transform, doing nothing ?!");
        }
    },
    function errorHandle(err){
        that.callback(err);
    }
  );
};

PostgresFormat.prototype.sendResponse = function(opts, callback) {
  if ( this.callback ) {
    callback(new Error("Invalid double call to .sendResponse on a pg formatter"));
    return;
  }
  this.callback = callback;
  this.opts = opts;

  this.hasSkipFields = opts.skipfields.length;

  var sql = this.getQuery(opts.sql, {
    gn: opts.gn,
    dp: opts.dp,
    skipfields: opts.skipfields
  });

  var that = this;

  this.start_time = Date.now();

  this.client = new PSQL(opts.dbopts, {}, { destroyOnError: true });
  this.client.eventedQuery(sql, function(err, query, queryCanceller) {
      that.queryCanceller = queryCanceller;
      if (err) {
        callback(err);
        return;
      }
      if ( that.opts.profiler ) {
          that.opts.profiler.done('eventedQuery');
      }

      if (that.hasSkipFields) {
          query.on('row', that.handleQueryRowWithSkipFields.bind(that));
      } else {
          query.on('row', that.handleQueryRow.bind(that));
      }
      query.on('end', that.handleQueryEnd.bind(that));
      query.on('error', function(err) {
          that.error = err;
          if (err.message && err.message.match(/row too large, was \d* bytes/i)) {
              console.error(JSON.stringify({
                  username: opts.username,
                  type: 'row_size_limit_exceeded',
                  error: err.message
              }));
          }
      });
      query.on('notice', function(msg) {
          that.handleNotice(msg, query._result);
      });
  });
};

PostgresFormat.prototype.cancel = function() {
    if (this.queryCanceller) {
        this.queryCanceller.call();
    }
};

module.exports = PostgresFormat;