// Copyright 2014, 2015 by Sascha L. Teichmann
// Use of this source code is governed by the MIT license
// that can be found in the LICENSE file.

package main

import (
	"bufio"
	"log"
	"net"
	"strconv"
)

var (
	redisOk          = []byte("+OK\r\n")
	redisPong        = []byte("+PONG\r\n")
	redisError       = []byte("-ERR\r\n")
	redisNoSuchBlock = []byte("$-1\r\n")
	redisCrnl        = []byte("\r\n")
	redisEmptyArray  = []byte("*0\r\n")
	redisQueued      = []byte("+QUEUED\r\n")
	redisTrue        = []byte(":1\r\n")
	redisFalse       = []byte(":0\r\n")
)

type connection struct {
	conn              net.Conn
	session           session
	maxBulkStringSize int64
	boolArray         []bool
}

func newConnection(conn net.Conn, sess session, maxBulkStringSize int64) *connection {
	return &connection{
		conn:              conn,
		session:           sess,
		maxBulkStringSize: maxBulkStringSize,
		boolArray:         []bool{}}
}

func (c *connection) run() {
	defer func() {
		c.session.close()
		c.conn.Close()
	}()
	r := bufio.NewReaderSize(c.conn, 8*1024)
	parser := newRedisParser(r, c, c.maxBulkStringSize)
	parser.parse()
	log.Println("client disconnected")
}

func logError(err error) bool {
	if err != nil {
		log.Printf("ERROR: %s\n", err)
		return false
	}
	return true
}

func (c *connection) hdel(hash, key []byte) bool {

	success, err := c.session.del(hash, key)
	if err != nil {
		return c.writeError(err)
	}

	return c.writeBool(success)
}

func (c *connection) hget(hash, key []byte) bool {

	var err error
	var data []byte
	if data, err = c.session.fetch(hash, key); err != nil {
		return c.writeError(err)
	}

	return c.writeBlock(data)
}

func (c *connection) hset(hash, key, data []byte) bool {

	var err error
	var exists bool
	if exists, err = c.session.store(hash, key, data); err != nil {
		return c.writeError(err)
	}

	if c.session.inTransaction() {
		c.boolArray = append(c.boolArray, exists)
		return c.writeQueued()
	}

	return c.writeBool(exists)
}

func (c *connection) multi() bool {
	if c.session.inTransaction() {
		log.Println("WARN: Already running transaction.")
	} else {
		if err := c.session.beginTransaction(); err != nil {
			return c.writeError(err)
		}
	}
	return c.writeOk()
}

func (c *connection) exec() bool {
	if !c.session.inTransaction() {
		return c.writeEmptyArray()
	}
	arr := c.boolArray
	c.boolArray = []bool{}
	if err := c.session.commitTransaction(); err != nil {
		return c.writeError(err)
	}
	return c.writeBoolArray(arr)
}

func (c *connection) hkeys(hash []byte) bool {
	var (
		err  error
		n    int
		keys <-chan []byte
		done = make(chan struct{})
	)
	defer close(done)

	if keys, n, err = c.session.allKeys(hash, done); err != nil {
		return c.writeError(err)
	}

	if n == 0 {
		return c.writeEmptyArray()
	}

	if _, err := c.conn.Write(redisLength('*', n)); err != nil {
		return logError(err)
	}

	for key := range keys {
		if err = c.writeBulkString(key); err != nil {
			return logError(err)
		}
	}
	return true
}

func (c *connection) ping() bool {
	return c.writeMessage(redisPong)
}

func (c *connection) hSpatial(hash, first, second []byte) bool {
	var (
		err    error
		blocks <-chan block
		done   = make(chan struct{})
	)
	defer close(done)

	if blocks, err = c.session.spatialQuery(hash, first, second, done); err != nil {
		return c.writeError(err)
	}

	for block := range blocks {
		if err = c.writeBulkString(block.Key); err != nil {
			return logError(err)
		}
		if err = c.writeBulkString(block.Data); err != nil {
			return logError(err)
		}
	}

	return logError(c.writeBulkString(nil))
}

func (c *connection) writeError(err error) bool {
	logError(err)
	return c.writeMessage(redisError)
}

func (c *connection) writeEmptyArray() bool {
	return c.writeMessage(redisEmptyArray)
}

func (c *connection) writeBool(b bool) bool {
	if b {
		return c.writeMessage(redisTrue)
	}
	return c.writeMessage(redisFalse)
}

func redisLength(prefix byte, s int) []byte {
	buf := append(make([]byte, 0, 16), prefix)
	return append(strconv.AppendInt(buf, int64(s), 10), '\r', '\n')
}

func (c *connection) writeBoolArray(arr []bool) bool {
	if _, err := c.conn.Write(redisLength('*', len(arr))); err != nil {
		return logError(err)
	}
	for _, b := range arr {
		if !c.writeBool(b) {
			return false
		}
	}
	return true
}

func (c *connection) writeMessage(msg []byte) bool {
	_, err := c.conn.Write(msg)
	return logError(err)
}

func (c *connection) writeOk() bool {
	return c.writeMessage(redisOk)
}

func (c *connection) writeQueued() bool {
	return c.writeMessage(redisQueued)
}

func (c *connection) writeBlock(data []byte) bool {
	return logError(c.writeBulkString(data))
}

func (c *connection) writeBulkString(data []byte) (err error) {
	con := c.conn
	if data == nil {
		_, err = con.Write(redisNoSuchBlock)
	} else {
		if _, err = con.Write(redisLength('$', len(data))); err != nil {
			return
		}
		if _, err = con.Write(data); err != nil {
			return
		}
		_, err = con.Write(redisCrnl)
	}
	return
}