package s3

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"

	"ultone/internal/log"

	"github.com/samber/lo"
)

type s3_dir struct {
	ctx context.Context
	dir string
}

func (s *s3_dir) clean() {
	now := time.Now()

	filepath.Walk(s.dir, func(p string, info fs.FileInfo, err error) error {
		if info.IsDir() {
			return nil
		}

		if strings.HasPrefix(info.Name(), ".meta_") {
			bs, err := os.ReadFile(p)
			if err != nil {
				log.Warn(s.ctx, "s3.by_dir: read meta err, err = %s", err.Error())
				return nil
			}

			nm := new(meta)
			if err = json.Unmarshal(bs, nm); err != nil {
				log.Warn(s.ctx, "s3.by_dir: unmarshal meta err, err = %s", err.Error())
				return nil
			}

			if nm.ExpireAt > 0 && time.UnixMilli(nm.ExpireAt).Before(now) {
				os.Remove(p)
				base := strings.TrimPrefix(info.Name(), ".meta_")
				dir := filepath.Dir(p)
				os.Remove(path.Join(dir, base))
			}
		}

		return nil
	})
}

// Delete implements S3.
func (s *s3_dir) Delete(ctx context.Context, bucket string, key string) error {
	location := path.Join(s.dir, bucket, key)
	info, err := os.Stat(location)
	if err != nil {
		return err
	}

	if info.IsDir() {
		return fmt.Errorf("target is dir")
	}

	os.Remove(path.Join(s.dir, bucket, ".meta_"+key))

	return os.Remove(location)
}

// Get implements S3.
func (s *s3_dir) Get(ctx context.Context, bucket string, key string) (*Object, error) {
	location := path.Join(s.dir, bucket, key)
	info, err := os.Stat(location)
	if err != nil {
		return nil, err
	}

	if info.IsDir() {
		return nil, fmt.Errorf("target is dir")
	}

	var (
		f   io.ReadCloser
		bs  []byte
		obj = &Object{}
	)

	if f, err = os.Open(location); err != nil {
		return nil, err
	}

	obj.Body = f

	if bs, err = os.ReadFile(path.Join(s.dir, bucket, ".meta_"+key)); err != nil {
		log.Warn(ctx, "s3.dir: open file meta err, err = %v", err)
		return obj, nil
	}

	m := new(meta)
	if err = json.Unmarshal(bs, m); err != nil {
		log.Warn(ctx, "s3.dir: unmarshal meta err, err = %v", err)
		return obj, nil
	}

	obj.ContentType = m.ContentType
	obj.Size = m.Size
	obj.ExpireAt = m.ExpireAt

	return obj, nil
}

// Put implements S3.
func (s *s3_dir) Put(ctx context.Context, bucket string, key string, obj *Object) error {
	if bucket != "" {
		os.MkdirAll(path.Join(s.dir, bucket), 0o755)
	}

	location := path.Join(s.dir, bucket, key)
	ml := path.Join(s.dir, bucket, ".meta_"+key)

	bs, err := io.ReadAll(obj.Body)
	if err != nil {
		return err
	}

	if obj.Size != 0 && obj.Size != int64(len(bs)) {
		return fmt.Errorf("object size mismatch")
	}

	obj.Size = int64(len(bs))

	if obj.ContentType == "" {
		obj.ContentType = http.DetectContentType(lo.If(len(bs) >= 128, bs[:128]).Else(bs))
	}

	if err = os.WriteFile(location, bs, 0o644); err != nil {
		return err
	}

	m := &meta{
		ContentType: obj.ContentType,
		Size:        obj.Size,
		ExpireAt:    obj.ExpireAt,
	}

	ms, _ := json.Marshal(m)
	os.WriteFile(ml, ms, 0o644)

	return nil
}

func newDirClient(ctx context.Context, dir string) (S3, error) {
	dir = filepath.ToSlash(dir)
	info, err := os.Stat(dir)
	if err != nil {
		if errors.Is(err, fs.ErrNotExist) {
			if err = os.MkdirAll(dir, 0o755); err != nil {
				return nil, err
			}
		}

		return nil, err
	}

	if !info.IsDir() {
		return nil, fmt.Errorf("target dir exist but not dir")
	}

	c := &s3_dir{ctx: ctx, dir: dir}

	// todo: expire files
	go func() {
		ticker := time.NewTicker(10 * time.Minute)
		for {
			select {
			case <-ctx.Done():
				return
			case t := <-ticker.C:
				log.Debug(ctx, "s3.by_dir: start clean up s3 dir @%s", t.Format("2006-01-02T15:04:05"))
				c.clean()
			}
		}
	}()

	return c, nil
}