"use strict";

var copy = require('../connection/utils').copy
  , retrieveBSON = require('../connection/utils').retrieveBSON
  , KillCursor = require('../connection/commands').KillCursor
  , GetMore = require('../connection/commands').GetMore
  , Query = require('../connection/commands').Query
  , f = require('util').format
  , MongoError = require('../error')
  , getReadPreference = require('./shared').getReadPreference;

var BSON = retrieveBSON(),
  Long = BSON.Long;

var WireProtocol = function() {}

//
// Execute a write operation
var executeWrite = function(pool, bson, type, opsField, ns, ops, options, callback) {
  if(ops.length == 0) throw new MongoError("insert must contain at least one document");
  if(typeof options == 'function') {
    callback = options;
    options = {};
    options = options || {};
  }

  // Split the ns up to get db and collection
  var p = ns.split(".");
  var d = p.shift();
  // Options
  var ordered = typeof options.ordered == 'boolean' ? options.ordered : true;
  var writeConcern = options.writeConcern;

  // return skeleton
  var writeCommand = {};
  writeCommand[type] = p.join('.');
  writeCommand[opsField] = ops;
  writeCommand.ordered = ordered;

  // Did we specify a write concern
  if(writeConcern && Object.keys(writeConcern).length > 0) {
    writeCommand.writeConcern = writeConcern;
  }

  // Do we have bypassDocumentValidation set, then enable it on the write command
  if(typeof options.bypassDocumentValidation == 'boolean') {
    writeCommand.bypassDocumentValidation = options.bypassDocumentValidation;
  }

  // Options object
  var opts = { command: true };
  var queryOptions = { checkKeys : false, numberToSkip: 0, numberToReturn: 1 };
  if(type == 'insert') queryOptions.checkKeys = true;
  // Ensure we support serialization of functions
  if(options.serializeFunctions) queryOptions.serializeFunctions = options.serializeFunctions;
  // Do not serialize the undefined fields
  if(options.ignoreUndefined) queryOptions.ignoreUndefined = options.ignoreUndefined;

  try {
    // Create write command
    var cmd = new Query(bson, f("%s.$cmd", d), writeCommand, queryOptions);
    // Execute command
    pool.write(cmd, opts, callback);
  } catch(err) {
    callback(err);
  }
}

//
// Needs to support legacy mass insert as well as ordered/unordered legacy
// emulation
//
WireProtocol.prototype.insert = function(pool, ismaster, ns, bson, ops, options, callback) {
  executeWrite(pool, bson, 'insert', 'documents', ns, ops, options, callback);
}

WireProtocol.prototype.update = function(pool, ismaster, ns, bson, ops, options, callback) {
  executeWrite(pool, bson, 'update', 'updates', ns, ops, options, callback);
}

WireProtocol.prototype.remove = function(pool, ismaster, ns, bson, ops, options, callback) {
  executeWrite(pool, bson, 'delete', 'deletes', ns, ops, options, callback);
}

WireProtocol.prototype.killCursor = function(bson, ns, cursorId, pool, callback) {
  // Create a kill cursor command
  var killCursor = new KillCursor(bson, [cursorId]);
  // Execute the kill cursor command
  if(pool && pool.isConnected()) {
    pool.write(killCursor, {
      immediateRelease:true, noResponse: true
    });
  }

  // Callback
  if(typeof callback == 'function') callback(null, null);
}

WireProtocol.prototype.getMore = function(bson, ns, cursorState, batchSize, raw, connection, options, callback) {
  // Create getMore command
  var getMore = new GetMore(bson, ns, cursorState.cursorId, {numberToReturn: batchSize});

  // Query callback
  var queryCallback = function(err, result) {
    if(err) return callback(err);
    // Get the raw message
    var r = result.message;

    // If we have a timed out query or a cursor that was killed
    if((r.responseFlags & (1 << 0)) != 0) {
      return callback(new MongoError("cursor does not exist, was killed or timed out"), null);
    }

    // Ensure we have a Long valie cursor id
    var cursorId = typeof r.cursorId == 'number'
      ? Long.fromNumber(r.cursorId)
      : r.cursorId;

    // Set all the values
    cursorState.documents = r.documents;
    cursorState.cursorId = cursorId;

    // Return
    callback(null, null, r.connection);
  }

  // If we have a raw query decorate the function
  if(raw) {
    queryCallback.raw = raw;
  }

  // Check if we need to promote longs
  if(typeof cursorState.promoteLongs == 'boolean') {
    queryCallback.promoteLongs = cursorState.promoteLongs;
  }

  if(typeof cursorState.promoteValues == 'boolean') {
    queryCallback.promoteValues = cursorState.promoteValues;
  }

  if(typeof cursorState.promoteBuffers == 'boolean') {
    queryCallback.promoteBuffers = cursorState.promoteBuffers;
  }

  // Write out the getMore command
  connection.write(getMore, queryCallback);
}

WireProtocol.prototype.command = function(bson, ns, cmd, cursorState, topology, options) {
  // Establish type of command
  if(cmd.find) {
    return setupClassicFind(bson, ns, cmd, cursorState, topology, options)
  } else if(cursorState.cursorId != null) {
    return;
  } else if(cmd) {
    return setupCommand(bson, ns, cmd, cursorState, topology, options);
  } else {
    throw new MongoError(f("command %s does not return a cursor", JSON.stringify(cmd)));
  }
}

//
// Execute a find command
var setupClassicFind = function(bson, ns, cmd, cursorState, topology, options) {
  // Ensure we have at least some options
  options = options || {};
  // Get the readPreference
  var readPreference = getReadPreference(cmd, options);
  // Set the optional batchSize
  cursorState.batchSize = cmd.batchSize || cursorState.batchSize;
  var numberToReturn = 0;

  // Unpack the limit and batchSize values
  if(cursorState.limit == 0) {
    numberToReturn = cursorState.batchSize;
  } else if(cursorState.limit < 0 || cursorState.limit < cursorState.batchSize || (cursorState.limit > 0 && cursorState.batchSize == 0)) {
    numberToReturn = cursorState.limit;
  } else {
    numberToReturn = cursorState.batchSize;
  }

  var numberToSkip = cursorState.skip || 0;
  // Build actual find command
  var findCmd = {};
  // Using special modifier
  var usesSpecialModifier = false;

  // We have a Mongos topology, check if we need to add a readPreference
  if(topology.type == 'mongos' && readPreference) {
    findCmd['$readPreference'] = readPreference.toJSON();
    usesSpecialModifier = true;
  }

  // Add special modifiers to the query
  if(cmd.sort) findCmd['orderby'] = cmd.sort, usesSpecialModifier = true;
  if(cmd.hint) findCmd['$hint'] = cmd.hint, usesSpecialModifier = true;
  if(cmd.snapshot) findCmd['$snapshot'] = cmd.snapshot, usesSpecialModifier = true;
  if(cmd.returnKey) findCmd['$returnKey'] = cmd.returnKey, usesSpecialModifier = true;
  if(cmd.maxScan) findCmd['$maxScan'] = cmd.maxScan, usesSpecialModifier = true;
  if(cmd.min) findCmd['$min'] = cmd.min, usesSpecialModifier = true;
  if(cmd.max) findCmd['$max'] = cmd.max, usesSpecialModifier = true;
  if(cmd.showDiskLoc) findCmd['$showDiskLoc'] = cmd.showDiskLoc, usesSpecialModifier = true;
  if(cmd.comment) findCmd['$comment'] = cmd.comment, usesSpecialModifier = true;
  if(cmd.maxTimeMS) findCmd['$maxTimeMS'] = cmd.maxTimeMS, usesSpecialModifier = true;

  if(cmd.explain) {
	// nToReturn must be 0 (match all) or negative (match N and close cursor)
	// nToReturn > 0 will give explain results equivalent to limit(0)
    numberToReturn = -Math.abs(cmd.limit || 0);
    usesSpecialModifier = true;
    findCmd['$explain'] = true;
  }

  // If we have a special modifier
  if(usesSpecialModifier) {
    findCmd['$query'] = cmd.query;
  } else {
    findCmd = cmd.query;
  }

  // Throw on majority readConcern passed in
  if(cmd.readConcern && cmd.readConcern.level != 'local') {
    throw new MongoError(f('server find command does not support a readConcern level of %s', cmd.readConcern.level));
  }

  // Remove readConcern, ensure no failing commands
  if(cmd.readConcern) {
    cmd = copy(cmd);
    delete cmd['readConcern'];
  }

  // Serialize functions
  var serializeFunctions = typeof options.serializeFunctions == 'boolean'
    ? options.serializeFunctions : false;
  var ignoreUndefined = typeof options.ignoreUndefined == 'boolean'
    ? options.ignoreUndefined : false;

  // Build Query object
  var query = new Query(bson, ns, findCmd, {
      numberToSkip: numberToSkip, numberToReturn: numberToReturn
    , checkKeys: false, returnFieldSelector: cmd.fields
    , serializeFunctions: serializeFunctions
    , ignoreUndefined: ignoreUndefined
  });

  // Set query flags
  query.slaveOk = readPreference.slaveOk();

  // Set up the option bits for wire protocol
  if(typeof cmd.tailable == 'boolean') {
    query.tailable = cmd.tailable;
  }

  if(typeof cmd.oplogReplay == 'boolean') {
    query.oplogReplay = cmd.oplogReplay;
  }

  if(typeof cmd.noCursorTimeout == 'boolean') {
    query.noCursorTimeout = cmd.noCursorTimeout;
  }

  if(typeof cmd.awaitData == 'boolean') {
    query.awaitData = cmd.awaitData;
  }

  if(typeof cmd.partial == 'boolean') {
    query.partial = cmd.partial;
  }

  // Return the query
  return query;
}

//
// Set up a command cursor
var setupCommand = function(bson, ns, cmd, cursorState, topology, options) {
  // Set empty options object
  options = options || {}
  // Get the readPreference
  var readPreference = getReadPreference(cmd, options);

  // Final query
  var finalCmd = {};
  for(var name in cmd) {
    finalCmd[name] = cmd[name];
  }

  // Build command namespace
  var parts = ns.split(/\./);

  // Serialize functions
  var serializeFunctions = typeof options.serializeFunctions == 'boolean'
    ? options.serializeFunctions : false;

  var ignoreUndefined = typeof options.ignoreUndefined == 'boolean'
    ? options.ignoreUndefined : false;

  // Throw on majority readConcern passed in
  if(cmd.readConcern && cmd.readConcern.level != 'local') {
    throw new MongoError(f('server %s command does not support a readConcern level of %s', JSON.stringify(cmd), cmd.readConcern.level));
  }

  // Remove readConcern, ensure no failing commands
  if(cmd.readConcern) delete cmd['readConcern'];

  // We have a Mongos topology, check if we need to add a readPreference
  if(topology.type == 'mongos'
    && readPreference
    && readPreference.preference != 'primary') {
    finalCmd = {
      '$query': finalCmd,
      '$readPreference': readPreference.toJSON()
    };
  }

  // Build Query object
  var query = new Query(bson, f('%s.$cmd', parts.shift()), finalCmd, {
      numberToSkip: 0, numberToReturn: -1
    , checkKeys: false, serializeFunctions: serializeFunctions
    , ignoreUndefined: ignoreUndefined
  });

  // Set query flags
  query.slaveOk = readPreference.slaveOk();

  // Return the query
  return query;
}

module.exports = WireProtocol;
