package repository

import (
	"database/sql"
	"fmt"
	"strings"

	"github.com/wmms/wmms/internal/model"
	"github.com/wmms/wmms/pkg/database"
)

// BeginTx starts a new database transaction
func BeginTx() (*sql.Tx, error) {
	return database.DB.Begin()
}

type MaterialRepo struct{}

func NewMaterialRepo() *MaterialRepo {
	return &MaterialRepo{}
}

func (r *MaterialRepo) Create(m *model.Material) error {
	query := `INSERT INTO materials (material_code, name, material_image, spec, category, unit, warning_stock) VALUES (?, ?, ?, ?, ?, ?, ?)`
	result, err := database.DB.Exec(query, m.MaterialCode, m.Name, m.MaterialImage, m.Spec, m.Category, m.Unit, m.WarningStock)
	if err != nil {
		if strings.Contains(err.Error(), "Duplicate entry") {
			return fmt.Errorf("material code already exists")
		}
		return err
	}
	id, err := result.LastInsertId()
	if err != nil {
		return err
	}
	m.ID = id
	return r.GetByID(m.ID, m)
}

func (r *MaterialRepo) GetByID(id int64, m *model.Material) error {
	query := `SELECT id, material_code, name, material_image, spec, category, unit, warning_stock, current_stock, created_at, updated_at FROM materials WHERE id = ?`
	var materialImage sql.NullString
	err := database.DB.QueryRow(query, id).Scan(&m.ID, &m.MaterialCode, &m.Name, &materialImage, &m.Spec, &m.Category, &m.Unit, &m.WarningStock, &m.CurrentStock, &m.CreatedAt, &m.UpdatedAt)
	if err != nil {
		return err
	}
	if materialImage.Valid {
		m.MaterialImage = &materialImage.String
	}
	return nil
}

func (r *MaterialRepo) GetByMaterialCode(code string) (*model.Material, error) {
	m := &model.Material{}
	query := `SELECT id, material_code, name, material_image, spec, category, unit, warning_stock, current_stock, created_at, updated_at FROM materials WHERE material_code = ?`
	var materialImage sql.NullString
	err := database.DB.QueryRow(query, code).Scan(&m.ID, &m.MaterialCode, &m.Name, &materialImage, &m.Spec, &m.Category, &m.Unit, &m.WarningStock, &m.CurrentStock, &m.CreatedAt, &m.UpdatedAt)
	if err != nil {
		return nil, err
	}
	if materialImage.Valid {
		m.MaterialImage = &materialImage.String
	}
	return m, nil
}

func (r *MaterialRepo) List(search, category string, limit, offset int) ([]model.Material, int64, error) {
	countQuery := `SELECT COUNT(*) FROM materials WHERE 1=1`
	var countArgs []interface{}

	if search != "" {
		countQuery += ` AND (material_code LIKE ? OR name LIKE ?)`
		searchPattern := "%" + search + "%"
		countArgs = append(countArgs, searchPattern, searchPattern)
	}
	if category != "" {
		countQuery += ` AND category = ?`
		countArgs = append(countArgs, category)
	}

	var total int64
	err := database.DB.QueryRow(countQuery, countArgs...).Scan(&total)
	if err != nil {
		return nil, 0, err
	}

	query := `SELECT id, material_code, name, material_image, spec, category, unit, warning_stock, current_stock, created_at, updated_at FROM materials WHERE 1=1`
	var args []interface{}

	if search != "" {
		query += ` AND (material_code LIKE ? OR name LIKE ?)`
		searchPattern := "%" + search + "%"
		args = append(args, searchPattern, searchPattern)
	}
	if category != "" {
		query += ` AND category = ?`
		args = append(args, category)
	}
	query += ` ORDER BY id DESC LIMIT ? OFFSET ?`
	args = append(args, limit, offset)

	rows, err := database.DB.Query(query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var materials []model.Material
	for rows.Next() {
		var m model.Material
		var materialImage sql.NullString
		err := rows.Scan(&m.ID, &m.MaterialCode, &m.Name, &materialImage, &m.Spec, &m.Category, &m.Unit, &m.WarningStock, &m.CurrentStock, &m.CreatedAt, &m.UpdatedAt)
		if err != nil {
			return nil, 0, err
		}
		if materialImage.Valid {
			m.MaterialImage = &materialImage.String
		}
		materials = append(materials, m)
	}
	return materials, total, nil
}

func (r *MaterialRepo) Update(id int64, req *model.UpdateMaterialRequest) error {
	var sets []string
	var args []interface{}

	if req.MaterialCode != "" {
		sets = append(sets, "material_code = ?")
		args = append(args, req.MaterialCode)
	}
	if req.Name != "" {
		sets = append(sets, "name = ?")
		args = append(args, req.Name)
	}
	if req.MaterialImage != "" {
		sets = append(sets, "material_image = ?")
		args = append(args, req.MaterialImage)
	}
	if req.Spec != "" {
		sets = append(sets, "spec = ?")
		args = append(args, req.Spec)
	}
	if req.Category != "" {
		sets = append(sets, "category = ?")
		args = append(args, req.Category)
	}
	if req.Unit != "" {
		sets = append(sets, "unit = ?")
		args = append(args, req.Unit)
	}
	if req.WarningStock > 0 {
		sets = append(sets, "warning_stock = ?")
		args = append(args, req.WarningStock)
	}

	if len(sets) == 0 {
		return nil
	}

	query := fmt.Sprintf("UPDATE materials SET %s WHERE id = ?", strings.Join(sets, ", "))
	args = append(args, id)
	_, err := database.DB.Exec(query, args...)
	return err
}

func (r *MaterialRepo) Delete(id int64) error {
	// Check if material has related records
	var count int

	// Check inbound_items
	database.DB.QueryRow(`SELECT COUNT(*) FROM inbound_items WHERE material_id = ?`, id).Scan(&count)
	if count > 0 {
		return fmt.Errorf("该物料有入库记录，无法删除")
	}

	// Check outbound_items
	database.DB.QueryRow(`SELECT COUNT(*) FROM outbound_items WHERE material_id = ?`, id).Scan(&count)
	if count > 0 {
		return fmt.Errorf("该物料有出库记录，无法删除")
	}

	// Check stock_logs
	database.DB.QueryRow(`SELECT COUNT(*) FROM stock_logs WHERE material_id = ?`, id).Scan(&count)
	if count > 0 {
		return fmt.Errorf("该物料有库存流水记录，无法删除")
	}

	_, err := database.DB.Exec(`DELETE FROM materials WHERE id = ?`, id)
	return err
}

func (r *MaterialRepo) UpdateStock(id int64, delta int) error {
	query := `UPDATE materials SET current_stock = current_stock + ? WHERE id = ?`
	result, err := database.DB.Exec(query, delta, id)
	if err != nil {
		return err
	}
	affected, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if affected == 0 {
		return sql.ErrNoRows
	}
	return nil
}

func (r *MaterialRepo) GetStock(id int64) (int, error) {
	var stock int
	query := `SELECT current_stock FROM materials WHERE id = ?`
	err := database.DB.QueryRow(query, id).Scan(&stock)
	return stock, err
}

// GetStockForUpdateTx gets stock with row lock within a transaction (prevents race condition)
func (r *MaterialRepo) GetStockForUpdateTx(tx *sql.Tx, id int64) (int, error) {
	query := `SELECT current_stock FROM materials WHERE id = ? FOR UPDATE`
	var stock int
	err := tx.QueryRow(query, id).Scan(&stock)
	return stock, err
}

// UpdateStockTx updates stock within a transaction
func (r *MaterialRepo) UpdateStockTx(tx *sql.Tx, id int64, delta int) error {
	query := `UPDATE materials SET current_stock = current_stock + ? WHERE id = ?`
	_, err := tx.Exec(query, delta, id)
	return err
}