package realname

import (
	"context"
	"errors"
	"strings"

	"hfb_sys/backend/internal/logging"
	"hfb_sys/backend/internal/model"
	"hfb_sys/backend/internal/modules/invitation"
	"hfb_sys/backend/pkg/crypto"

	"go.uber.org/zap"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

const idNoFingerprintDomain = "realname_id"

type Repository struct {
	db        *gorm.DB
	encryptor crypto.Encryptor
	idHashKey string
}

func NewRepository(db *gorm.DB, encryptor crypto.Encryptor, idHashKey string) *Repository {
	if encryptor == nil {
		encryptor = &crypto.MockEncryptor{}
	}
	return &Repository{db: db, encryptor: encryptor, idHashKey: strings.TrimSpace(idHashKey)}
}

func (r *Repository) FindByUserID(ctx context.Context, userID uint64) (*model.UserRealname, error) {
	var record model.UserRealname
	if err := r.db.WithContext(ctx).Where("user_id = ?", userID).First(&record).Error; err != nil {
		return nil, err
	}
	return &record, nil
}

// IsVerifiedUser 判断当前账号是否已经完成实名认证。
func (r *Repository) IsVerifiedUser(ctx context.Context, userID uint64) (bool, error) {
	var userStatus string
	if err := r.db.WithContext(ctx).Model(&model.User{}).
		Where("id = ?", userID).Pluck("realname_status", &userStatus).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return false, nil
		}
		return false, err
	}
	if userStatus == "verified" {
		return true, nil
	}
	var count int64
	err := r.db.WithContext(ctx).Model(&model.UserRealname{}).
		Where("user_id = ? AND status = ?", userID, StatusVerified).
		Count(&count).Error
	return count > 0, err
}

// ExistsVerifiedIdentity 判断身份证是否已绑定到其他已实名账号。
// 新记录直接查 HMAC 指纹；存量记录没有指纹时按脱敏号取候选并解密精确比对，
// 命中后顺手补写指纹，避免每次重复解密。
func (r *Repository) ExistsVerifiedIdentity(ctx context.Context, userID uint64, idNo string) (bool, error) {
	idNo = normalizeIDNo(idNo)
	if idNo == "" {
		return false, nil
	}
	idNoHash := FingerprintIDNo(r.idHashKey, idNo)

	var count int64
	if err := r.db.WithContext(ctx).Model(&model.UserRealname{}).
		Where("status = ? AND id_no_hash = ? AND user_id <> ?", StatusVerified, idNoHash, userID).
		Count(&count).Error; err != nil {
		return false, err
	}
	if count > 0 {
		return true, nil
	}

	masked := maskIDNo(idNo)
	var candidates []model.UserRealname
	if err := r.db.WithContext(ctx).
		Where("status = ? AND user_id <> ? AND masked_id_no = ?", StatusVerified, userID, masked).
		Find(&candidates).Error; err != nil {
		return false, err
	}
	for _, candidate := range candidates {
		plain, err := r.encryptor.Decrypt(candidate.EncryptedIDNo)
		if err != nil {
			logging.FromContext(ctx).Warn("实名存量身份证解密失败，无法完成唯一性比对",
				zap.String("module", "realname"),
				zap.Uint64("realname_id", candidate.ID),
				zap.Error(err),
			)
			continue
		}
		if normalizeIDNo(plain) != idNo {
			continue
		}
		if candidate.IDNoHash == nil || *candidate.IDNoHash != idNoHash {
			r.backfillIDNoHash(ctx, candidate.ID, idNoHash)
		}
		return true, nil
	}
	return false, nil
}

func (r *Repository) backfillIDNoHash(ctx context.Context, recordID uint64, idNoHash string) {
	err := r.db.WithContext(ctx).Model(&model.UserRealname{}).
		Where("id = ? AND (id_no_hash IS NULL OR id_no_hash <> ?)", recordID, idNoHash).
		Update("id_no_hash", idNoHash).Error
	if err != nil && !isDuplicateIDNoError(err) {
		logging.FromContext(ctx).Warn("实名身份证指纹回填失败",
			zap.String("module", "realname"),
			zap.Uint64("realname_id", recordID),
			zap.Error(err),
		)
	}
}

// SaveResult 保存实名结果并更新用户实名状态。idNoHash 仅认证通过时写入。
func (r *Repository) SaveResult(ctx context.Context, userID uint64, provider string, result ProviderResult, idNoHash string) (*model.UserRealname, error) {
	record := model.UserRealname{
		UserID:          userID,
		Provider:        provider,
		ProviderOrderNo: result.ProviderOrderNo,
		Status:          result.Status,
		MaskedName:      result.MaskedName,
		EncryptedName:   result.EncryptedName,
		MaskedIDNo:      result.MaskedIDNo,
		EncryptedIDNo:   result.EncryptedIDNo,
		VerifiedAt:      result.VerifiedAt,
		FailReason:      result.FailReason,
	}
	if result.Status == StatusVerified && strings.TrimSpace(idNoHash) != "" {
		hash := strings.TrimSpace(idNoHash)
		record.IDNoHash = &hash
	}

	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var existing model.UserRealname
		findErr := tx.Clauses(clause.Locking{Strength: "UPDATE"}).
			Where("user_id = ?", userID).First(&existing).Error
		switch {
		case findErr == nil:
			existing.Provider = record.Provider
			existing.ProviderOrderNo = record.ProviderOrderNo
			existing.Status = record.Status
			existing.MaskedName = record.MaskedName
			existing.EncryptedName = record.EncryptedName
			existing.MaskedIDNo = record.MaskedIDNo
			existing.EncryptedIDNo = record.EncryptedIDNo
			existing.IDNoHash = record.IDNoHash
			existing.VerifiedAt = record.VerifiedAt
			existing.FailReason = record.FailReason
			if err := tx.Save(&existing).Error; err != nil {
				if isDuplicateIDNoError(err) {
					return ErrIDNoAlreadyUsed
				}
				return err
			}
		case errors.Is(findErr, gorm.ErrRecordNotFound):
			if err := tx.Create(&record).Error; err != nil {
				if isDuplicateIDNoError(err) {
					return ErrIDNoAlreadyUsed
				}
				return err
			}
		default:
			return findErr
		}

		userStatus := StatusRejected
		if result.Status == StatusVerified {
			userStatus = "verified"
		}
		if result.Status == StatusPending {
			userStatus = "pending"
		}
		if err := tx.Model(&model.User{}).Where("id = ?", userID).Update("realname_status", userStatus).Error; err != nil {
			return err
		}
		if userStatus == "verified" {
			_ = invitation.OnUserRealnameVerifiedTx(tx, userID)
		}
		return nil
	})
	if err != nil {
		return nil, err
	}
	return r.FindByUserID(ctx, userID)
}

// FingerprintIDNo 生成身份证号的稳定盲索引。
func FingerprintIDNo(secret, idNo string) string {
	return crypto.FingerprintHMAC(secret, idNoFingerprintDomain, normalizeIDNo(idNo))
}

func normalizeIDNo(idNo string) string {
	return strings.ToUpper(strings.TrimSpace(idNo))
}

func isDuplicateIDNoError(err error) bool {
	if err == nil {
		return false
	}
	if errors.Is(err, gorm.ErrDuplicatedKey) {
		return true
	}
	text := strings.ToLower(err.Error())
	return strings.Contains(text, "1062") && strings.Contains(text, "uk_user_realname_id_no_hash")
}

// IsIDNoDuplicateError 供其他模块复用身份证唯一键冲突判断。
func IsIDNoDuplicateError(err error) bool {
	return isDuplicateIDNoError(err)
}