package services

import (
	"errors"
	"fmt"
	"regexp"
	"strings"

	"gauth-central/internal/database"
	"gauth-central/internal/models"

	"gorm.io/gorm"
)

const defaultHomeVideoURL = "https://www.youtube.com/watch?v=6zM4p_A0ISk"

type HomeService struct{}

func NewHomeService() *HomeService {
	return &HomeService{}
}

// CreateHome creates a new home entry with optional tag relations.
func (s *HomeService) CreateHome(
	name string,
	title string,
	button1 string,
	button2 string,
	video string,
	keywords string,
	image string,
	tagIDs []string,
	isActive bool,
) (*models.Home, error) {
	if strings.TrimSpace(video) == "" {
		video = defaultHomeVideoURL
	}

	slug := s.generateUniqueSlug(slugify(name), "")

	home := models.Home{
		Name:     name,
		Title:    title,
		Button1:  button1,
		Button2:  button2,
		Video:    video,
		Keywords: keywords,
		Image:    image,
		Slug:     slug,
		IsActive: isActive,
	}

	if len(tagIDs) > 0 {
		tags, err := s.fetchTagsByIDs(tagIDs)
		if err != nil {
			return nil, err
		}
		home.Tags = tags
	}

	if err := database.DB.Create(&home).Error; err != nil {
		return nil, err
	}

	return s.GetHomeByID(home.ID.String())
}

// GetAllHomes retrieves all homes. Use onlyActive to filter public data.
func (s *HomeService) GetAllHomes(onlyActive bool) ([]models.Home, error) {
	var homes []models.Home
	query := database.DB.Preload("Tags").Order("created_at desc")
	if onlyActive {
		query = query.Where("is_active = ?", true)
	}

	if err := query.Find(&homes).Error; err != nil {
		return nil, err
	}

	return homes, nil
}

// GetHomeByID retrieves a home by ID.
func (s *HomeService) GetHomeByID(id string) (*models.Home, error) {
	var home models.Home
	if err := database.DB.Preload("Tags").Where("id = ?", id).First(&home).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("home not found")
		}
		return nil, err
	}
	return &home, nil
}

// GetHomeBySlug retrieves a home by slug. Use onlyActive to limit public access.
func (s *HomeService) GetHomeBySlug(slug string, onlyActive bool) (*models.Home, error) {
	var home models.Home
	query := database.DB.Preload("Tags").Where("slug = ?", slug)
	if onlyActive {
		query = query.Where("is_active = ?", true)
	}

	if err := query.First(&home).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("home not found")
		}
		return nil, err
	}

	return &home, nil
}

// UpdateHome updates an existing home entry and its tag relations.
func (s *HomeService) UpdateHome(
	id string,
	name *string,
	title *string,
	button1 *string,
	button2 *string,
	video *string,
	keywords *string,
	image *string,
	slug *string,
	tagIDs *[]string,
	isActive *bool,
) (*models.Home, error) {
	home, err := s.GetHomeByID(id)
	if err != nil {
		return nil, err
	}

	updates := map[string]interface{}{}
	if name != nil {
		updates["name"] = *name
	}
	if title != nil {
		updates["title"] = *title
	}
	if button1 != nil {
		updates["button1"] = *button1
	}
	if button2 != nil {
		updates["button2"] = *button2
	}
	if video != nil {
		updates["video"] = *video
	}
	if keywords != nil {
		updates["keywords"] = *keywords
	}
	if image != nil {
		updates["image"] = *image
	}
	if slug != nil {
		clean := slugify(*slug)
		if clean == "" {
			return nil, errors.New("slug cannot be empty")
		}
		if s.slugExists(clean, id) {
			return nil, errors.New("slug already exists")
		}
		updates["slug"] = clean
	}
	if isActive != nil {
		updates["is_active"] = *isActive
	}

	if len(updates) > 0 {
		if err := database.DB.Model(home).Updates(updates).Error; err != nil {
			return nil, err
		}
	}

	if tagIDs != nil {
		tags, err := s.fetchTagsByIDs(*tagIDs)
		if err != nil {
			return nil, err
		}
		if err := database.DB.Model(home).Association("Tags").Replace(tags); err != nil {
			return nil, err
		}
	}

	return s.GetHomeByID(id)
}

// DeleteHome deletes a home by ID.
func (s *HomeService) DeleteHome(id string) error {
	result := database.DB.Delete(&models.Home{}, "id = ?", id)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return errors.New("home not found")
	}
	return nil
}

func (s *HomeService) fetchTagsByIDs(tagIDs []string) ([]models.Tag, error) {
	var tags []models.Tag
	if len(tagIDs) == 0 {
		return tags, nil
	}

	if err := database.DB.Where("id IN ?", tagIDs).Find(&tags).Error; err != nil {
		return nil, err
	}
	if len(tags) != len(tagIDs) {
		return nil, errors.New("one or more tags not found")
	}
	return tags, nil
}

func (s *HomeService) generateUniqueSlug(baseSlug string, excludeID string) string {
	slug := baseSlug
	counter := 1
	for s.slugExists(slug, excludeID) {
		slug = fmt.Sprintf("%s-%d", baseSlug, counter)
		counter++
	}
	return slug
}

func (s *HomeService) slugExists(slug string, excludeID string) bool {
	var count int64
	query := database.DB.Model(&models.Home{}).Where("slug = ?", slug)
	if excludeID != "" {
		query = query.Where("id <> ?", excludeID)
	}
	query.Count(&count)
	return count > 0
}

func slugify(input string) string {
	clean := strings.TrimSpace(input)
	if clean == "" {
		return ""
	}

	replacer := strings.NewReplacer(
		"ı", "i",
		"İ", "i",
		"ş", "s",
		"Ş", "s",
		"ğ", "g",
		"Ğ", "g",
		"ç", "c",
		"Ç", "c",
		"ö", "o",
		"Ö", "o",
		"ü", "u",
		"Ü", "u",
	)

	clean = strings.ToLower(replacer.Replace(clean))
	re := regexp.MustCompile(`[^a-z0-9]+`)
	clean = re.ReplaceAllString(clean, "-")
	clean = strings.Trim(clean, "-")
	if clean == "" {
		return "home"
	}
	return clean
}