package services

import (
	"crypto/rand"
	"encoding/base64"
	"encoding/hex"
	"errors"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/google/uuid"
	qr "github.com/yeqown/go-qrcode/v2"
	"github.com/yeqown/go-qrcode/writer/standard"

	"git.beifan.cn/trace-system/backend-go/database"
	"git.beifan.cn/trace-system/backend-go/models"
)

// SerialsService 序列号服务
type SerialsService struct{}

// Generate 生成序列号
func (s *SerialsService) Generate(
	companyName string,
	quantity int,
	validDays int,
	userId uint,
	prefix ...string,
) ([]models.Serial, error) {
	var serials []models.Serial
	validUntil := time.Now().AddDate(0, 0, validDays)

	// 检查公司是否存在，不存在则创建
	var company models.Company
	result := database.DB.Where("company_name = ?", companyName).First(&company)
	if result.Error != nil {
		company = models.Company{
			CompanyName: companyName,
			IsActive:    true,
		}
		result = database.DB.Create(&company)
		if result.Error != nil {
			return nil, fmt.Errorf("创建公司失败: %w", result.Error)
		}
	}

	// 生成序列号前缀
	var serialPrefix string
	if len(prefix) > 0 && prefix[0] != "" {
		serialPrefix = strings.ToUpper(strings.ReplaceAll(prefix[0], "[^A-Z0-9]", ""))
	} else {
		serialPrefix = fmt.Sprintf("BF%d", time.Now().Year()%100)
	}

	// 预生成所有序列号
	serialNumbers := make(map[string]bool)
	for i := 0; i < quantity; {
		randomBytes := make([]byte, 3)
		if _, err := rand.Read(randomBytes); err != nil {
			return nil, fmt.Errorf("生成随机数失败: %w", err)
		}
		randomPart := hex.EncodeToString(randomBytes)[:6]
		serialNumber := fmt.Sprintf("%s%s", serialPrefix, randomPart)

		if serialNumbers[serialNumber] {
			continue
		}

		var existingSerial models.Serial
		checkResult := database.DB.Where("serial_number = ?", serialNumber).First(&existingSerial)
		if checkResult.Error != nil {
			serialNumbers[serialNumber] = true
			i++
		}
	}

	for serialNumber := range serialNumbers {
		serial := models.Serial{
			SerialNumber: strings.ToUpper(serialNumber),
			CompanyName:  companyName,
			ValidUntil:   &validUntil,
			CreatedBy:    &userId,
			IsActive:     true,
		}
		serials = append(serials, serial)
	}

	// 保存到数据库
	result = database.DB.Create(&serials)
	if result.Error != nil {
		return nil, fmt.Errorf("保存序列号失败: %w", result.Error)
	}

	return serials, nil
}

// GenerateQRCode 生成二维码
func (s *SerialsService) GenerateQRCode(
	serialNumber string,
	baseUrl string,
	requestHost string,
	protocol string,
) (string, string, error) {
	var serial models.Serial
	result := database.DB.Preload("User").Where("serial_number = ?", strings.ToUpper(serialNumber)).First(&serial)
	if result.Error != nil {
		return "", "", fmt.Errorf("查询序列号失败: %w", errors.New("序列号不存在"))
	}

	if !serial.IsActive {
		return "", "", fmt.Errorf("序列号状态无效: %w", errors.New("序列号已被禁用"))
	}

	if serial.ValidUntil != nil && serial.ValidUntil.Before(time.Now()) {
		return "", "", fmt.Errorf("序列号已过期")
	}

	// 确定查询 URL
	if baseUrl == "" {
		baseUrl = fmt.Sprintf("%s://%s/query.html", protocol, requestHost)
	}

	var queryUrl string
	if strings.Contains(baseUrl, "?") {
		queryUrl = fmt.Sprintf("%s&serial=%s", baseUrl, serial.SerialNumber)
	} else {
		queryUrl = fmt.Sprintf("%s?serial=%s", baseUrl, serial.SerialNumber)
	}

	// 生成二维码到临时文件
	filePath := fmt.Sprintf("temp_qr_%s.png", uuid.New().String())
	writer, err := standard.New(filePath, standard.WithQRWidth(6))
	if err != nil {
		return "", "", fmt.Errorf("二维码写入器创建失败: %w", err)
	}

	qrc, errCode := qr.New(queryUrl)
	if errCode != nil {
		os.Remove(filePath)
		return "", "", fmt.Errorf("二维码创建失败: %w", errCode)
	}

	if errSave := qrc.Save(writer); errSave != nil {
		os.Remove(filePath)
		return "", "", fmt.Errorf("二维码保存失败: %w", errSave)
	}

	// 读取文件内容
	fileContent, errRead := os.ReadFile(filePath)
	if errRead != nil {
		os.Remove(filePath)
		return "", "", fmt.Errorf("二维码文件读取失败: %w", errRead)
	}

	// 删除临时文件
	os.Remove(filePath)

	// 转换为 base64
	qrCodeBase64 := fmt.Sprintf("data:image/png;base64,%s", base64.StdEncoding.EncodeToString(fileContent))
	return qrCodeBase64, queryUrl, nil
}

// Query 查询序列号信息
func (s *SerialsService) Query(serialNumber string) (*models.Serial, error) {
	var serial models.Serial
	result := database.DB.Preload("User").Where("serial_number = ?", strings.ToUpper(serialNumber)).First(&serial)
	if result.Error != nil {
		return nil, fmt.Errorf("查询序列号失败: %w", errors.New("序列号不存在"))
	}

	if serial.ValidUntil != nil && serial.ValidUntil.Before(time.Now()) {
		return nil, fmt.Errorf("序列号已过期")
	}

	return &serial, nil
}

// FindAll 获取序列号列表
func (s *SerialsService) FindAll(page int, limit int, search string) ([]models.Serial, int, int, error) {
	var serials []models.Serial
	var total int64

	offset := (page - 1) * limit
	db := database.DB.Preload("User")

	// 搜索条件
	if search != "" {
		db = db.Where("serial_number LIKE ? OR company_name LIKE ?", "%"+search+"%", "%"+search+"%")
	}

	// 获取总数
	countQuery := db.Model(&models.Serial{})
	if search != "" {
		countQuery = countQuery.Where("serial_number LIKE ? OR company_name LIKE ?", "%"+search+"%", "%"+search+"%")
	}
	countQuery.Count(&total)

	// 分页查询
	result := db.Model(&models.Serial{}).Order("created_at DESC").Offset(offset).Limit(limit).Find(&serials)
	if result.Error != nil {
		return nil, 0, 0, fmt.Errorf("查询序列号列表失败: %w", result.Error)
	}

	totalPages := (int(total) + limit - 1) / limit

	return serials, int(total), totalPages, nil
}

// Update 更新序列号信息
func (s *SerialsService) Update(serialNumber string, updateData models.UpdateSerialDTO) (*models.Serial, error) {
	var serial models.Serial
	result := database.DB.Where("serial_number = ?", strings.ToUpper(serialNumber)).First(&serial)
	if result.Error != nil {
		return nil, fmt.Errorf("查询序列号失败: %w", errors.New("序列号不存在"))
	}

	if updateData.CompanyName != "" {
		// 检查公司是否存在
		var company models.Company
		companyResult := database.DB.Where("company_name = ?", updateData.CompanyName).First(&company)
		if companyResult.Error != nil {
			company = models.Company{
				CompanyName: updateData.CompanyName,
				IsActive:    true,
			}
			database.DB.Create(&company)
		}

		serial.CompanyName = updateData.CompanyName
	}

	if updateData.ValidUntil != nil {
		serial.ValidUntil = updateData.ValidUntil
	}

	if updateData.IsActive != nil {
		serial.IsActive = *updateData.IsActive
	}

	result = database.DB.Save(&serial)
	if result.Error != nil {
		return nil, fmt.Errorf("更新序列号失败: %w", result.Error)
	}

	_ = database.DB.Preload("User").Where("serial_number = ?", serial.SerialNumber).First(&serial)

	return &serial, nil
}

// Revoke 吊销序列号
func (s *SerialsService) Revoke(serialNumber string) error {
	var serial models.Serial
	result := database.DB.Where("serial_number = ?", strings.ToUpper(serialNumber)).First(&serial)
	if result.Error != nil {
		return fmt.Errorf("查询序列号失败: %w", errors.New("序列号不存在"))
	}

	if !serial.IsActive {
		return fmt.Errorf("序列号状态无效: %w", errors.New("序列号已被吊销"))
	}

	serial.IsActive = false
	result = database.DB.Save(&serial)
	if result.Error != nil {
		return fmt.Errorf("吊销序列号失败: %w", result.Error)
	}

	return nil
}