package services

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"
	"jd-book-uploader/models"
	"jd-book-uploader/utils"
)

// CreateBook creates a new book record in the database
func CreateBook(ctx context.Context, req *models.BookCreateRequest) (*models.Book, error) {
	if DB == nil {
		return nil, fmt.Errorf("database connection not initialized")
	}

	// Generate UUID for book_code
	bookCode := uuid.New().String()

	// Generate slug from book name
	slug := utils.GenerateSlug(req.BookName)

	// Set default discount if not provided
	discount := req.Discount
	if discount < 0 {
		discount = 0
	}

	now := time.Now()

	// Insert book into database
	query := `
		INSERT INTO books (
			book_code, book_name, cost, price, discount, quantity,
			publisher_author, category, description, image_url, slug,
			created_at, updated_at
		) VALUES (
			$1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13
		) RETURNING 
			book_code, book_name, cost, price, discount, quantity,
			publisher_author, category, description, image_url, slug,
			created_at, updated_at
	`

	var book models.Book
	err := DB.QueryRow(ctx, query,
		bookCode,
		req.BookName,
		req.Cost,
		req.Price,
		discount,
		req.Quantity,
		req.PublisherAuthor,
		req.Category,
		req.Description,
		req.ImageURL,
		slug,
		now,
		now,
	).Scan(
		&book.BookCode,
		&book.BookName,
		&book.Cost,
		&book.Price,
		&book.Discount,
		&book.Quantity,
		&book.PublisherAuthor,
		&book.Category,
		&book.Description,
		&book.ImageURL,
		&book.Slug,
		&book.CreatedAt,
		&book.UpdatedAt,
	)

	if err != nil {
		// Check for duplicate key error
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) {
			if pgErr.Code == "23505" { // unique_violation
				return nil, fmt.Errorf("book with this code already exists")
			}
		}
		return nil, fmt.Errorf("failed to create book: %w", err)
	}

	return &book, nil
}

// GetBookByCode retrieves a book by its code
func GetBookByCode(ctx context.Context, bookCode string) (*models.Book, error) {
	if DB == nil {
		return nil, fmt.Errorf("database connection not initialized")
	}

	query := `
		SELECT 
			book_code, book_name, cost, price, discount, quantity,
			publisher_author, category, description, image_url, slug,
			created_at, updated_at
		FROM books
		WHERE book_code = $1
	`

	var book models.Book
	err := DB.QueryRow(ctx, query, bookCode).Scan(
		&book.BookCode,
		&book.BookName,
		&book.Cost,
		&book.Price,
		&book.Discount,
		&book.Quantity,
		&book.PublisherAuthor,
		&book.Category,
		&book.Description,
		&book.ImageURL,
		&book.Slug,
		&book.CreatedAt,
		&book.UpdatedAt,
	)

	if err != nil {
		if err == pgx.ErrNoRows {
			return nil, fmt.Errorf("book not found")
		}
		return nil, fmt.Errorf("failed to get book: %w", err)
	}

	return &book, nil
}

// BookSlugExists checks if a slug already exists in the books table
func BookSlugExists(ctx context.Context, slug string) (bool, error) {
	if DB == nil {
		return false, fmt.Errorf("database connection not initialized")
	}

	query := `SELECT EXISTS(SELECT 1 FROM books WHERE slug = $1)`
	var exists bool
	err := DB.QueryRow(ctx, query, slug).Scan(&exists)
	if err != nil {
		return false, fmt.Errorf("failed to check slug existence: %w", err)
	}

	return exists, nil
}