package file

import (
	"context"
	"errors"
	"mime/multipart"
	"strings"
)

var (
	ErrDependencyUnavailable = errors.New("dependency unavailable")
	ErrInvalidFile           = errors.New("invalid file")
)

const maxUploadSize = 10 * 1024 * 1024

var allowedContentTypes = map[string]bool{
	"image/jpeg":      true,
	"image/png":       true,
	"image/webp":      true,
	"application/pdf": true,
}

type Service struct {
	storage *Storage
}

func NewService(storage *Storage) *Service {
	return &Service{storage: storage}
}

func (s *Service) Upload(req uploadRequest) (*UploadDTO, error) {
	if s.storage == nil {
		return nil, ErrDependencyUnavailable
	}
	if req.Header == nil || req.Reader == nil || req.Header.Size <= 0 || req.Header.Size > maxUploadSize {
		return nil, ErrInvalidFile
	}
	contentType := req.ContentType
	if contentType == "" {
		contentType = req.Header.Header.Get("Content-Type")
	}
	if !allowedContentTypes[contentType] {
		return nil, ErrInvalidFile
	}
	scene := normalizeScene(req.Scene)
	key, err := s.storage.Put(req.Context, scene, req.Header, req.Reader, contentType)
	if err != nil {
		return nil, err
	}
	return &UploadDTO{
		ObjectKey:   key,
		URL:         "/api/files/object?key=" + key,
		Filename:    req.Header.Filename,
		ContentType: contentType,
		Size:        req.Header.Size,
	}, nil
}

func normalizeScene(scene string) string {
	scene = strings.TrimSpace(strings.ToLower(scene))
	switch scene {
	case "listing", "handoff", "dispute", "realname", "avatar":
		return scene
	default:
		return "misc"
	}
}

type uploadRequest struct {
	Context     context.Context
	Scene       string
	Header      *multipart.FileHeader
	Reader      multipart.File
	ContentType string
}