package main

import (
	"bytes"
	"crypto/rand"
	"encoding/json"
	"fmt"
	"math/big"
	"os"
	"text/template"

	log "github.com/sirupsen/logrus"

	"github.com/Luzifer/rconfig/v2"
	"github.com/Luzifer/twitch-bot/v3/plugins"
)

var (
	cfg = struct {
		BotRespond     bool   `flag:"bot-respond,b" default:"false" description:"Wrap output in a respond directive for twitch-bot"`
		Count          int64  `flag:"count,c" default:"1" description:"How many dice to throw?"`
		LogLevel       string `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"`
		Sides          int64  `flag:"sides,s" default:"6" description:"How many sides does the dice have?"`
		Template       string `flag:"template" vardefault:"tpl" description:"Template to format the result with"`
		Type           string `flag:"type,t" default:"dice" description:"What to throw (coin, dice)"`
		VersionAndExit bool   `flag:"version" default:"false" description:"Prints current version and exits"`
	}{}

	version = "dev"
)

func init() {
	rconfig.AutoEnv(true)
	rconfig.SetVariableDefaults(map[string]string{
		"tpl": `I threw {{.count}}x {{if eq .type "coin"}}coin{{else}}W{{.sides}}{{end}} for you and got:{{ range .results}} {{ if eq $.type "coin" }}{{ if eq . 1 }}Head{{ else }}Number{{ end }}{{ else }}{{ . }}{{ end }}{{ end }}`,
	})
	if err := rconfig.ParseAndValidate(&cfg); err != nil {
		log.Fatalf("Unable to parse commandline options: %s", err)
	}

	if cfg.VersionAndExit {
		fmt.Printf("dice %s\n", version)
		os.Exit(0)
	}

	if l, err := log.ParseLevel(cfg.LogLevel); err != nil {
		log.WithError(err).Fatal("Unable to parse log level")
	} else {
		log.SetLevel(l)
	}
}

func main() {
	var (
		results []int64
		sum     int64
	)

	switch cfg.Type {
	case "coin":
		results, sum = getResults(2, cfg.Count)

	case "dice":
		if cfg.Sides == 0 {
			// There is no [0..0] dice.
			log.Fatal("There is no 0-sided dice")
		}
		results, sum = getResults(cfg.Sides, cfg.Count)

	default:
		log.WithField("type", cfg.Type).Fatal("Don't know how to throw that")
	}

	t, err := template.New("output").Parse(cfg.Template)
	if err != nil {
		log.WithError(err).Fatal("Unable to parse template")
	}

	text := new(bytes.Buffer)
	if err = t.Execute(text, map[string]interface{}{
		"count":   cfg.Count,
		"results": results,
		"sides":   cfg.Sides,
		"sum":     sum,
		"type":    cfg.Type,
	}); err != nil {
		log.WithError(err).Fatal("Unable to execute template")
	}

	if !cfg.BotRespond {
		fmt.Println(text.String())
		return
	}

	output := []plugins.RuleAction{
		{
			Type: "respond",
			Attributes: plugins.FieldCollectionFromData(map[string]any{
				"message": text.String(),
			}),
		},
	}

	if err = json.NewEncoder(os.Stdout).Encode(output); err != nil {
		log.WithError(err).Fatal("Unable to encode bot response")
	}
}

func getRandomNumber(sides int64) int64 {
	n, _ := rand.Int(rand.Reader, big.NewInt(sides))
	return n.Int64()
}

func getResults(sides, count int64) (res []int64, sum int64) {
	for i := int64(0); i < count; i++ {
		v := getRandomNumber(sides) + 1
		res = append(res, v)
		sum += v
	}

	return res, sum
}