package main

import (
	"context"
	"io"
	"log"
	"math/rand"
	"net/http"
	"os"
	"strings"
	"text/template"
	"time"

	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
	"gopkg.in/yaml.v3"
)

type ImageProvider interface {
	GetImage() string
}

type LocalProvider struct{}

type S3Provider struct {
	confHundler ConfHandler
}

func (p LocalProvider) GetImage() string {
	return GetRandImg()
}

func (p S3Provider) GetImage() string {
	return p.confHundler.GetRandImgS3()
}

func GetPicsArray() []string {
	files, err := os.ReadDir("images")
	if err != nil {
		log.Printf("Ошибка чтения директории: %v", err)
		return []string{}
	}
	if len(files) == 0 {
		return []string{"no images"}
	}
	var filesNames = make([]string, len(files))
	for i, file := range files {
		filesNames[i] = string("images/" + file.Name())
	}
	return filesNames
}

func (conf *ConfHandler) GetRandImgS3() string {
	picsArray := GetObjectsFilenames(conf.ConfigHandler, *conf.minioClient)
	return picsArray[rand.Intn(len(picsArray))]
}

func GetRandImg() string {
	picsArray := GetPicsArray()
	if len(picsArray) == 0 {
		return ""
	}
	return picsArray[rand.Intn(len(picsArray))]
}

func ReturnPicFilename(provider ImageProvider) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		image := provider.GetImage()
		io.Copy(w, strings.NewReader(image))
		log.Println("Картинка отдана")
	}
}

func ReturnHTML(provider ImageProvider) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		htmlOpen, err := template.ParseFiles("dist/index.html")
		if err != nil {
			log.Println(err.Error())
			return
		}
		image := provider.GetImage()
		if err := htmlOpen.Execute(w, image); err != nil {
			log.Printf("Ошибка рендеринга: %v", err)
		}
	}
}

type Config struct {
	UseS3     bool   `yaml:"use_s3"`
	Address   string `yaml:"address"`
	Bucket    string `yaml:"bucket"`
	AccessKey string `yaml:"access_key"`
	SecretKey string `yaml:"secret_key"`
}

type ConfHandler struct {
	ConfigHandler Config
	minioClient   *minio.Client
}

func InitConf(filename string) Config {
	var conf Config
	configFile, _ := os.ReadFile(filename)
	err := yaml.Unmarshal(configFile, &conf)
	if err != nil {
		log.Fatal(err)
	}

	return conf
}

func GetObjectsFilenames(conf Config, minioClient minio.Client) []string {

	ctx, cancel := context.WithCancel(context.Background())

	defer cancel()

	objectCh := minioClient.ListObjects(ctx, conf.Bucket, minio.ListObjectsOptions{Recursive: false})

	log.Println(objectCh)
	objectsKeyArr := []string{}

	for object := range objectCh {
		if object.Err != nil {
			log.Println(object.Err)
		}
		objectsKeyArr = append(objectsKeyArr, "https://"+conf.Address+"/"+conf.Bucket+"/"+object.Key)
	}
	return objectsKeyArr
}

func main() {
	log.Println("Server Start")
	rand.New(rand.NewSource(time.Now().UnixNano()))
	conf := InitConf("config.yaml")
	imagesDir := http.FileServer(http.Dir("images"))
	staticDir := http.FileServer(http.Dir("dist/assets"))
	http.Handle("/images/", http.StripPrefix("/images/", imagesDir))
	http.Handle("/assets/", http.StripPrefix("/assets/", staticDir))

	var provider ImageProvider

	if !conf.UseS3 {
		provider = LocalProvider{}
	} else {
		minioClient, err := minio.New(conf.Address, &minio.Options{
			Creds:  credentials.NewStaticV4(conf.AccessKey, conf.SecretKey, ""),
			Secure: true,
		})

		if err != nil {
			log.Fatalln(err)
		}
		provider = S3Provider{
			confHundler: ConfHandler{
				ConfigHandler: conf,
				minioClient:   minioClient,
			},
		}
	}
	http.HandleFunc("/rand", ReturnPicFilename(provider))
	http.HandleFunc("/", ReturnHTML(provider))
	http.ListenAndServe(":3666", nil)
}