package service

import (
	"context"

	"github.com/calendarapi/internal/models"
	"github.com/calendarapi/internal/repository"
	"github.com/calendarapi/internal/utils"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

type TagService struct {
	queries *repository.Queries
}

func NewTagService(queries *repository.Queries) *TagService {
	return &TagService{queries: queries}
}

type CreateTagRequest struct {
	Name  string
	Color *string
}

type UpdateTagRequest struct {
	Name  *string
	Color *string
}

func (s *TagService) Create(ctx context.Context, userID uuid.UUID, req CreateTagRequest) (*models.Tag, error) {
	if len(req.Name) < 1 || len(req.Name) > 50 {
		return nil, models.NewValidationError("tag name must be 1-50 characters")
	}
	color := "#6B7280"
	if req.Color != nil {
		if err := utils.ValidateColor(*req.Color); err != nil {
			return nil, err
		}
		color = *req.Color
	}

	id := uuid.New()
	t, err := s.queries.CreateTag(ctx, repository.CreateTagParams{
		ID:      utils.ToPgUUID(id),
		OwnerID: utils.ToPgUUID(userID),
		Name:    req.Name,
		Column4: color,
	})
	if err != nil {
		return nil, models.ErrInternal
	}

	tag := tagFromDB(t)
	return &tag, nil
}

func (s *TagService) Get(ctx context.Context, userID uuid.UUID, tagID uuid.UUID) (*models.Tag, error) {
	t, err := s.queries.GetTagByID(ctx, repository.GetTagByIDParams{
		ID:      utils.ToPgUUID(tagID),
		OwnerID: utils.ToPgUUID(userID),
	})
	if err != nil {
		if err == pgx.ErrNoRows {
			return nil, models.ErrNotFound
		}
		return nil, models.ErrInternal
	}
	tag := tagFromDB(t)
	return &tag, nil
}

func (s *TagService) List(ctx context.Context, userID uuid.UUID) ([]models.Tag, error) {
	rows, err := s.queries.ListTagsByOwner(ctx, utils.ToPgUUID(userID))
	if err != nil {
		return nil, models.ErrInternal
	}

	tags := make([]models.Tag, 0, len(rows))
	for _, r := range rows {
		tags = append(tags, tagFromDB(r))
	}
	return tags, nil
}

func (s *TagService) Update(ctx context.Context, userID uuid.UUID, tagID uuid.UUID, req UpdateTagRequest) (*models.Tag, error) {
	if req.Name != nil && (len(*req.Name) < 1 || len(*req.Name) > 50) {
		return nil, models.NewValidationError("tag name must be 1-50 characters")
	}
	if req.Color != nil {
		if err := utils.ValidateColor(*req.Color); err != nil {
			return nil, err
		}
	}

	updateParams := repository.UpdateTagParams{
		ID:      utils.ToPgUUID(tagID),
		OwnerID: utils.ToPgUUID(userID),
	}
	if req.Name != nil {
		updateParams.Name = utils.ToPgTextPtr(req.Name)
	}
	if req.Color != nil {
		updateParams.Color = utils.ToPgTextPtr(req.Color)
	}

	t, err := s.queries.UpdateTag(ctx, updateParams)
	if err != nil {
		if err == pgx.ErrNoRows {
			return nil, models.ErrNotFound
		}
		return nil, models.ErrInternal
	}
	tag := tagFromDB(t)
	return &tag, nil
}

func (s *TagService) Delete(ctx context.Context, userID uuid.UUID, tagID uuid.UUID) error {
	err := s.queries.DeleteTag(ctx, repository.DeleteTagParams{
		ID:      utils.ToPgUUID(tagID),
		OwnerID: utils.ToPgUUID(userID),
	})
	if err != nil {
		return models.ErrInternal
	}
	return nil
}

func (s *TagService) AttachToTask(ctx context.Context, userID uuid.UUID, tagID uuid.UUID, taskID uuid.UUID) error {
	if _, err := s.queries.GetTagByID(ctx, repository.GetTagByIDParams{
		ID:      utils.ToPgUUID(tagID),
		OwnerID: utils.ToPgUUID(userID),
	}); err != nil {
		if err == pgx.ErrNoRows {
			return models.ErrNotFound
		}
		return models.ErrInternal
	}
	return s.queries.AttachTagToTask(ctx, repository.AttachTagToTaskParams{
		TaskID: utils.ToPgUUID(taskID),
		TagID:  utils.ToPgUUID(tagID),
	})
}

func (s *TagService) DetachFromTask(ctx context.Context, userID uuid.UUID, tagID uuid.UUID, taskID uuid.UUID) error {
	if _, err := s.queries.GetTagByID(ctx, repository.GetTagByIDParams{
		ID:      utils.ToPgUUID(tagID),
		OwnerID: utils.ToPgUUID(userID),
	}); err != nil {
		if err == pgx.ErrNoRows {
			return models.ErrNotFound
		}
		return models.ErrInternal
	}
	return s.queries.DetachTagFromTask(ctx, repository.DetachTagFromTaskParams{
		TaskID: utils.ToPgUUID(taskID),
		TagID:  utils.ToPgUUID(tagID),
	})
}