package commands

import (
	"errors"
	"redisClone/pkg/core"
)
func SingleKey(args []string) []string {
    return []string{args[1]}
}

func AllSubsequentKeys(args []string) []string {
    return args[1:]
}

func NoKeys(args []string) []string {
    return nil
}

type CommandDef struct{
	MinArgs int
	ExtractKeys func(args []string)[]string
	Execute func(args []string, getShard func(k string) *core.Shard) interface{}
}

func DispatchBaseCommand(db core.RedisDB ,commandName string, args []string) interface{} {
    cmd, exists := Registry[commandName]
    if !exists {
        return nil
    }

    if len(args) < cmd.MinArgs {
        return errors.New("wrong number of arguments")
    }

    keys := cmd.ExtractKeys(args)
    
    db.Lock(keys)
    defer db.Unlock(keys)
    return cmd.Execute(args, db.GetShard)
}

var Registry = map[string]CommandDef{
    "GET": {
        MinArgs:     2,
        ExtractKeys: SingleKey,
        Execute: Get,
    },
	"SET": {
		MinArgs:	3,
		ExtractKeys: SingleKey,
		Execute: Set,
	},
    "DEL": {
        MinArgs:     2,
        ExtractKeys: AllSubsequentKeys,
        Execute: Del,
    },
}