package services

import (
	"context"
	"encoding/base64"
	"errors"
	"fmt"
	"strconv"
	"strings"
	"time"

	"gogs.fxtmmsk.ru/foxtime/photoplaces/backend/internal/models"
)

func encodeCursor(p *models.Place) string {
	s := p.ID + "|" + strconv.FormatInt(p.CreatedAt.UnixNano(), 10) + "|" + fmt.Sprintf("%.6f", p.Rating)
	return base64.RawURLEncoding.EncodeToString([]byte(s))
}

func DecodeCursor(cursor string) (id string, createdAt time.Time, rating float64, err error) {
	b, err := base64.RawURLEncoding.DecodeString(cursor)
	if err != nil {
		return "", time.Time{}, 0, fmt.Errorf("decode cursor: %w", err)
	}
	parts := strings.SplitN(string(b), "|", 3)
	if len(parts) < 2 {
		return "", time.Time{}, 0, fmt.Errorf("invalid cursor format")
	}
	id = parts[0]
	createdAtUnix, err := strconv.ParseInt(parts[1], 10, 64)
	if err != nil {
		return "", time.Time{}, 0, fmt.Errorf("parse cursor created_at: %w", err)
	}
	createdAt = time.Unix(0, createdAtUnix)
	if len(parts) > 2 {
		rating, _ = strconv.ParseFloat(parts[2], 64)
	}
	return
}

var (
	ErrNotYourPlace = errors.New("not your place")
	ErrPlaceNotFound = errors.New("place not found")
)

type PlaceRepo interface {
	Create(ctx context.Context, place *models.Place) error
	GetByID(ctx context.Context, id string) (*models.Place, error)
	List(ctx context.Context, filter models.PlaceFilter) ([]*models.Place, error)
	Update(ctx context.Context, place *models.Place) error
	UpdateStatus(ctx context.Context, id, status, comment string) error
	SoftDelete(ctx context.Context, id string) error
	SetTags(ctx context.Context, placeID string, tags []models.Tag) error
	SetFeatures(ctx context.Context, placeID string, features []models.Feature) error
	GetTags(ctx context.Context, placeID string) ([]models.Tag, error)
	GetFeatures(ctx context.Context, placeID string) ([]models.Feature, error)
	GetTagsBatch(ctx context.Context, placeIDs []string) (map[string][]models.Tag, error)
	GetFeaturesBatch(ctx context.Context, placeIDs []string) (map[string][]models.Feature, error)
}

type PlaceService struct {
	placeRepo PlaceRepo
}

func NewPlaceService(placeRepo PlaceRepo) *PlaceService {
	return &PlaceService{placeRepo: placeRepo}
}

type CreatePlaceInput struct {
	OwnerID    string
	Type       string
	Title      string
	Description *string
	Address    *string
	Lat        float64
	Lng        float64
	CoverImage *string
	AccessInfo *string
	HourlyRate *int
	Currency   string
	MinHours   int
	Tags       []models.Tag
	Features   []models.Feature
}

func (s *PlaceService) Create(ctx context.Context, input CreatePlaceInput) (*models.Place, error) {
	place := &models.Place{
		Type:       input.Type,
		OwnerID:    input.OwnerID,
		Title:      input.Title,
		Description: input.Description,
		Address:    input.Address,
		Lat:        input.Lat,
		Lng:        input.Lng,
		CoverImage: input.CoverImage,
		AccessInfo: input.AccessInfo,
		Status:     "pending_moderation",
		HourlyRate: input.HourlyRate,
		Currency:   input.Currency,
		MinHours:   input.MinHours,
		Tags:       input.Tags,
		Features:   input.Features,
	}

	if err := s.placeRepo.Create(ctx, place); err != nil {
		return nil, fmt.Errorf("create place: %w", err)
	}

	return place, nil
}

func (s *PlaceService) GetByID(ctx context.Context, id string, fetchTags bool) (*models.Place, error) {
	place, err := s.placeRepo.GetByID(ctx, id)
	if err != nil {
		return nil, err
	}
	if place == nil {
		return nil, nil
	}

	if fetchTags {
		tags, err := s.placeRepo.GetTags(ctx, id)
		if err != nil {
			return nil, err
		}
		place.Tags = tags

		features, err := s.placeRepo.GetFeatures(ctx, id)
		if err != nil {
			return nil, err
		}
		place.Features = features
	}

	return place, nil
}

func (s *PlaceService) List(ctx context.Context, filter models.PlaceFilter) (*models.PaginatedPlaces, error) {
	places, err := s.placeRepo.List(ctx, filter)
	if err != nil {
		return nil, err
	}

	if filter.IncludeTagsFeatures && len(places) > 0 {
		placeIDs := make([]string, len(places))
		for i, p := range places {
			placeIDs[i] = p.ID
		}

		tagsMap, err := s.placeRepo.GetTagsBatch(ctx, placeIDs)
		if err != nil {
			return nil, err
		}

		featuresMap, err := s.placeRepo.GetFeaturesBatch(ctx, placeIDs)
		if err != nil {
			return nil, err
		}

		for _, p := range places {
			if tags, ok := tagsMap[p.ID]; ok {
				p.Tags = tags
			}
			if features, ok := featuresMap[p.ID]; ok {
				p.Features = features
			}
		}
	}

	limit := filter.Limit()
	hasMore := len(places) > limit
	if hasMore {
		places = places[:limit]
	}

	var nextCursor string
	if hasMore && len(places) > 0 {
		nextCursor = encodeCursor(places[len(places)-1])
	}

	return &models.PaginatedPlaces{
		Data:       places,
		NextCursor: nextCursor,
		HasMore:    hasMore,
	}, nil
}

type UpdatePlaceInput struct {
	ID         string
	OwnerID    string
	Title      *string
	Description *string
	Address    *string
	Lat        *float64
	Lng        *float64
	CoverImage *string
	AccessInfo *string
	HourlyRate *int
	Currency   *string
	MinHours   *int
}

func (s *PlaceService) Update(ctx context.Context, input UpdatePlaceInput, isModerator bool) (*models.Place, error) {
	place, err := s.placeRepo.GetByID(ctx, input.ID)
	if err != nil {
		return nil, err
	}
	if place == nil {
		return nil, nil
	}

	if !isModerator && place.OwnerID != input.OwnerID {
		return nil, fmt.Errorf("%w: user %s tried to update place %s", ErrNotYourPlace, input.OwnerID, input.ID)
	}

	if input.Title != nil { place.Title = *input.Title }
	if input.Description != nil { place.Description = input.Description }
	if input.Address != nil { place.Address = input.Address }
	if input.Lat != nil { place.Lat = *input.Lat }
	if input.Lng != nil { place.Lng = *input.Lng }
	if input.CoverImage != nil { place.CoverImage = input.CoverImage }
	if input.AccessInfo != nil { place.AccessInfo = input.AccessInfo }
	if input.HourlyRate != nil { place.HourlyRate = input.HourlyRate }
	if input.Currency != nil { place.Currency = *input.Currency }
	if input.MinHours != nil { place.MinHours = *input.MinHours }

	if !isModerator {
		place.Status = "pending_moderation"
	}

	if err := s.placeRepo.Update(ctx, place); err != nil {
		return nil, err
	}

	return place, nil
}

func (s *PlaceService) Moderate(ctx context.Context, id, action, comment, moderatorID string) error {
	var status string
	switch action {
	case "approve":
		status = "published"
	case "reject":
		status = "rejected"
	default:
		return fmt.Errorf("unknown action: %s", action)
	}

	return s.placeRepo.UpdateStatus(ctx, id, status, comment)
}

func (s *PlaceService) Delete(ctx context.Context, id string) error {
	return s.placeRepo.SoftDelete(ctx, id)
}