package repository

import (
	"context"
	"regexp"
	"strings"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"

	"shop/internal/models"
)

type CategoryRepository struct {
	pool *pgxpool.Pool
}

func NewCategoryRepository(pool *pgxpool.Pool) *CategoryRepository {
	return &CategoryRepository{pool: pool}
}

var slugRe = regexp.MustCompile(`[^a-z0-9]+`)

func Slugify(name string) string {
	translit := map[rune]string{
		'а': "a", 'б': "b", 'в': "v", 'г': "g", 'д': "d", 'е': "e", 'ё': "e",
		'ж': "zh", 'з': "z", 'и': "i", 'й': "y", 'к': "k", 'л': "l", 'м': "m",
		'н': "n", 'о': "o", 'п': "p", 'р': "r", 'с': "s", 'т': "t", 'у': "u",
		'ф': "f", 'х': "h", 'ц': "ts", 'ч': "ch", 'ш': "sh", 'щ': "sch",
		'ъ': "", 'ы': "y", 'ь': "", 'э': "e", 'ю': "yu", 'я': "ya",
	}
	var b strings.Builder
	for _, r := range strings.ToLower(name) {
		if t, ok := translit[r]; ok {
			b.WriteString(t)
		} else if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') {
			b.WriteRune(r)
		} else if r == ' ' || r == '-' {
			b.WriteRune('-')
		}
	}
	s := slugRe.ReplaceAllString(b.String(), "-")
	return strings.Trim(s, "-")
}

func (r *CategoryRepository) All(ctx context.Context) ([]models.Category, error) {
	rows, err := r.pool.Query(ctx, `
		SELECT c.id, c.name, c.slug, c.description, c.sort_order,
		       COUNT(p.id) FILTER (WHERE p.is_active = true) AS cnt
		FROM categories c
		LEFT JOIN products p ON p.category_id = c.id
		GROUP BY c.id
		ORDER BY c.sort_order, c.name
	`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var list []models.Category
	for rows.Next() {
		var c models.Category
		if err := rows.Scan(&c.ID, &c.Name, &c.Slug, &c.Description, &c.SortOrder, &c.Count); err != nil {
			return nil, err
		}
		list = append(list, c)
	}
	return list, rows.Err()
}

func (r *CategoryRepository) GetBySlug(ctx context.Context, slug string) (models.Category, error) {
	var c models.Category
	err := r.pool.QueryRow(ctx, `
		SELECT id, name, slug, description, sort_order FROM categories WHERE slug = $1
	`, slug).Scan(&c.ID, &c.Name, &c.Slug, &c.Description, &c.SortOrder)
	return c, err
}

func (r *CategoryRepository) GetByID(ctx context.Context, id int) (models.Category, error) {
	var c models.Category
	err := r.pool.QueryRow(ctx, `
		SELECT id, name, slug, description, sort_order FROM categories WHERE id = $1
	`, id).Scan(&c.ID, &c.Name, &c.Slug, &c.Description, &c.SortOrder)
	return c, err
}

func (r *CategoryRepository) Create(ctx context.Context, name, description string) (models.Category, error) {
	slug := Slugify(name)
	var c models.Category
	err := r.pool.QueryRow(ctx, `
		INSERT INTO categories (name, slug, description)
		VALUES ($1, $2, $3)
		ON CONFLICT (slug) DO UPDATE SET name = EXCLUDED.name
		RETURNING id, name, slug, description, sort_order
	`, name, slug, description).Scan(&c.ID, &c.Name, &c.Slug, &c.Description, &c.SortOrder)
	return c, err
}

func (r *CategoryRepository) Update(ctx context.Context, c *models.Category) error {
	tag, err := r.pool.Exec(ctx, `
		UPDATE categories SET name = $1, slug = $2, description = $3, sort_order = $4 WHERE id = $5
	`, c.Name, c.Slug, c.Description, c.SortOrder, c.ID)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return pgx.ErrNoRows
	}
	return nil
}

func (r *CategoryRepository) Delete(ctx context.Context, id int) error {
	_, err := r.pool.Exec(ctx, `UPDATE products SET category_id = NULL WHERE category_id = $1`, id)
	if err != nil {
		return err
	}
	tag, err := r.pool.Exec(ctx, `DELETE FROM categories WHERE id = $1`, id)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return pgx.ErrNoRows
	}
	return nil
}