package drive

import (
	"context"
	"errors"
	"io"
	"net/http"
	"os"
	"path"
	"strconv"
	"strings"
	"time"

	"github.com/ultisuite/ulti-backend/internal/api/paginate"
	"github.com/ultisuite/ulti-backend/internal/api/query"
	"github.com/ultisuite/ulti-backend/internal/nextcloud"
)

var (
	ErrNotFound      = errors.New("not found")
	ErrConflict      = errors.New("conflict")
	ErrForbidden     = errors.New("forbidden")
	ErrQuotaExceeded = errors.New("quota exceeded")
	ErrInvalid       = errors.New("invalid request")
)

type Service struct {
	nc               *nextcloud.Client
	maxUploadBytes   int64
	quotaReserveByte int64
}

func NewService(nc *nextcloud.Client) *Service {
	return &Service{
		nc:               nc,
		maxUploadBytes:   envInt64("ULTID_DRIVE_MAX_UPLOAD_BYTES", 0),
		quotaReserveByte: envInt64("ULTID_DRIVE_QUOTA_RESERVED_BYTES", 0),
	}
}

type FilesList struct {
	Files      []nextcloud.FileInfo `json:"files"`
	Pagination query.PaginationMeta `json:"pagination,omitempty"`
}

func (s *Service) ListFiles(ctx context.Context, userID, path string, params query.ListParams) (FilesList, error) {
	if path == "" {
		path = "/"
	}
	files, err := s.nc.ListFiles(ctx, userID, path)
	if err != nil {
		return FilesList{}, mapDriveError(err)
	}
	filtered := filterFiles(files, params.Q)
	page, total := paginate.Slice(filtered, params.Offset(), params.Limit())
	return FilesList{
		Files:      page,
		Pagination: params.Meta(&total),
	}, nil
}

func (s *Service) ListTrash(ctx context.Context, userID string, params query.ListParams) (FilesList, error) {
	files, err := s.nc.ListTrash(ctx, userID)
	if err != nil {
		return FilesList{}, mapDriveError(err)
	}
	filtered := filterFiles(files, params.Q)
	page, total := paginate.Slice(filtered, params.Offset(), params.Limit())
	return FilesList{
		Files:      page,
		Pagination: params.Meta(&total),
	}, nil
}

func (s *Service) ListRecent(ctx context.Context, userID string, params query.ListParams) (FilesList, error) {
	files, err := s.nc.ListRecent(ctx, userID, params.Limit())
	if err != nil {
		return FilesList{}, mapDriveError(err)
	}
	filtered := filterFiles(files, params.Q)
	page, total := paginate.Slice(filtered, params.Offset(), params.Limit())
	return FilesList{
		Files:      page,
		Pagination: params.Meta(&total),
	}, nil
}

func (s *Service) ListStarred(ctx context.Context, userID, basePath string, params query.ListParams) (FilesList, error) {
	if basePath == "" {
		basePath = "/"
	}
	files, err := s.nc.ListFiles(ctx, userID, basePath)
	if err != nil {
		return FilesList{}, mapDriveError(err)
	}
	starred := make([]nextcloud.FileInfo, 0, len(files))
	for _, f := range files {
		if f.IsFavorite {
			starred = append(starred, f)
		}
	}
	filtered := filterFiles(starred, params.Q)
	page, total := paginate.Slice(filtered, params.Offset(), params.Limit())
	return FilesList{
		Files:      page,
		Pagination: params.Meta(&total),
	}, nil
}

func (s *Service) Upload(ctx context.Context, userID, path string, body io.Reader, contentType string, contentLength int64) error {
	if err := s.ensureQuota(ctx, userID, contentLength); err != nil {
		return err
	}
	return mapDriveError(s.nc.Upload(ctx, userID, path, body, contentType))
}

func (s *Service) UploadChunk(ctx context.Context, userID, uploadID, targetPath string, chunk ChunkUpload, body io.Reader, contentType string) error {
	if err := mapDriveError(s.nc.UploadChunk(ctx, userID, uploadID, chunkName(chunk.Index), body, contentType)); err != nil {
		return err
	}
	if !chunk.Complete {
		return nil
	}

	if err := s.ensureQuota(ctx, userID, chunk.TotalSize); err != nil {
		_ = s.nc.AbortChunkUpload(ctx, userID, uploadID)
		return err
	}
	if err := mapDriveError(s.nc.AssembleChunks(ctx, userID, uploadID, targetPath, chunk.TotalSize)); err != nil {
		return err
	}
	return nil
}

func (s *Service) Download(ctx context.Context, userID, path string) (io.ReadCloser, string, error) {
	body, contentType, err := s.nc.Download(ctx, userID, path)
	if err != nil {
		return nil, "", mapDriveError(err)
	}
	return body, contentType, nil
}

func (s *Service) Delete(ctx context.Context, userID, path string) error {
	return mapDriveError(s.nc.Delete(ctx, userID, path))
}

func (s *Service) CreateFolder(ctx context.Context, userID, path string) error {
	return mapDriveError(s.nc.CreateFolder(ctx, userID, path))
}

func (s *Service) Move(ctx context.Context, userID, source, destination string) error {
	return mapDriveError(s.nc.Move(ctx, userID, source, destination))
}

func (s *Service) Copy(ctx context.Context, userID, source, destination string) error {
	return mapDriveError(s.nc.Copy(ctx, userID, source, destination))
}

func (s *Service) Rename(ctx context.Context, userID, filePath, newName string) error {
	if strings.Contains(newName, "/") {
		return ErrInvalid
	}
	dir := path.Dir("/" + strings.TrimPrefix(filePath, "/"))
	destination := path.Join(dir, newName)
	return mapDriveError(s.nc.Move(ctx, userID, filePath, destination))
}

func (s *Service) CreateShare(ctx context.Context, userID, filePath string, shareType, permissions int) (*nextcloud.ShareInfo, error) {
	share, err := s.nc.CreateShare(ctx, userID, filePath, shareType, permissions)
	if err != nil {
		return nil, mapDriveError(err)
	}
	return share, nil
}

func filterFiles(files []nextcloud.FileInfo, q string) []nextcloud.FileInfo {
	q = strings.ToLower(strings.TrimSpace(q))
	if q == "" {
		return files
	}
	out := make([]nextcloud.FileInfo, 0, len(files))
	for _, f := range files {
		if strings.Contains(strings.ToLower(f.Name), q) ||
			strings.Contains(strings.ToLower(f.Path), q) {
			out = append(out, f)
		}
	}
	return out
}

type ChunkUpload struct {
	Index     int
	Total     int
	TotalSize int64
	Complete  bool
}

func chunkName(index int) string {
	return strconv.FormatInt(int64(index), 10)
}

func (s *Service) ensureQuota(ctx context.Context, userID string, incomingBytes int64) error {
	if s.maxUploadBytes > 0 && incomingBytes > s.maxUploadBytes {
		return ErrQuotaExceeded
	}
	quota, err := s.nc.GetQuota(ctx, userID)
	if err != nil {
		return mapDriveError(err)
	}
	if incomingBytes <= 0 {
		return nil
	}
	if quota.Free <= 0 {
		return ErrQuotaExceeded
	}
	if incomingBytes+s.quotaReserveByte > quota.Free {
		return ErrQuotaExceeded
	}
	return nil
}

func mapDriveError(err error) error {
	if err == nil {
		return nil
	}
	var statusErr *nextcloud.HTTPStatusError
	if !errors.As(err, &statusErr) {
		return err
	}
	switch statusErr.StatusCode {
	case http.StatusNotFound:
		return ErrNotFound
	case http.StatusConflict:
		return ErrConflict
	case http.StatusForbidden, http.StatusUnauthorized:
		return ErrForbidden
	case http.StatusInsufficientStorage, http.StatusRequestEntityTooLarge:
		return ErrQuotaExceeded
	case http.StatusBadRequest:
		return ErrInvalid
	default:
		return err
	}
}

func envInt64(key string, fallback int64) int64 {
	raw := strings.TrimSpace(os.Getenv(key))
	if raw == "" {
		return fallback
	}
	n, err := strconv.ParseInt(raw, 10, 64)
	if err != nil {
		return fallback
	}
	return n
}

func parseModTime(value string) time.Time {
	if value == "" {
		return time.Time{}
	}
	if t, err := time.Parse(time.RFC3339, value); err == nil {
		return t
	}
	if t, err := time.Parse(time.RFC1123, value); err == nil {
		return t
	}
	return time.Time{}
}