package main

import (
    "log"
    "strings"
    "sync"

    "github.com/tidwall/redcon"
)

var addr = ":6380"

func main() {
    var mu sync.RWMutex
    var items = make(map[string]string)
    go log.Printf("started server at %s", addr)
    err := redcon.ListenAndServe(addr,
        func(conn redcon.Conn, commands [][]string) {
            for _, args := range commands {
                switch strings.ToLower(args[0]) {
                default:
                    conn.WriteError("ERR unknown command '" + args[0] + "'")
                case "ping":
                    conn.WriteString("PONG")
                case "quit":
                    conn.WriteString("OK")
                    conn.Close()
                case "set":
                    if len(args) != 3 {
                        conn.WriteError("ERR wrong number of arguments for '" + args[0] + "' command")
                        continue
                    }
                    mu.Lock()
                    items[args[1]] = args[2]
                    mu.Unlock()
                    conn.WriteString("OK")
                case "get":
                    if len(args) != 2 {
                        conn.WriteError("ERR wrong number of arguments for '" + args[0] + "' command")
                        continue
                    }
                    mu.RLock()
                    val, ok := items[args[1]]
                    mu.RUnlock()
                    if !ok {
                        conn.WriteNull()
                    } else {
                        conn.WriteBulk(val)
                    }
                case "del":
                    if len(args) != 2 {
                        conn.WriteError("ERR wrong number of arguments for '" + args[0] + "' command")
                        continue
                    }
                    mu.Lock()
                    _, ok := items[args[1]]
                    delete(items, args[1])
                    mu.Unlock()
                    if !ok {
                        conn.WriteInt(0)
                    } else {
                        conn.WriteInt(1)
                    }
                }
            }
        },
        func(conn redcon.Conn) bool {
            // use this function to accept or deny the connection.
            // log.Printf("accept: %s", conn.RemoteAddr())
            return true
        },
        func(conn redcon.Conn, err error) {
            // this is called when the connection has been closed
            // log.Printf("closed: %s, err: %v", conn.RemoteAddr(), err)
        },
    )
    if err != nil {
        log.Fatal(err)
    }
}