package repository

import (
	"context"
	"errors"
	"fmt"

	"gorm.io/gorm"
	"pay-bridge/internal/model"
)

// SequenceRepository 序列数据访问
type SequenceRepository struct {
	db *gorm.DB
}

func NewSequenceRepository(db *gorm.DB) *SequenceRepository {
	return &SequenceRepository{db: db}
}

// IncrAndGet 原子自增并返回新值（行级锁）
func (r *SequenceRepository) IncrAndGet(ctx context.Context, appID string, seqType model.SeqType) (uint64, error) {
	var seq model.OrderSequence

	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		// 加行锁读取
		if err := tx.Set("gorm:query_option", "FOR UPDATE").
			Where("app_id = ? AND seq_type = ?", appID, seqType).
			First(&seq).Error; err != nil {
			if !errors.Is(err, gorm.ErrRecordNotFound) {
				return err
			}
			// 自动初始化序列
			prefix := defaultPrefix(seqType)
			seq = model.OrderSequence{
				AppID:        appID,
				SeqType:      seqType,
				Prefix:       prefix,
				CurrentValue: 0,
				Step:         1,
			}
			if err := tx.Create(&seq).Error; err != nil {
				return err
			}
			// 重新加锁读
			return tx.Set("gorm:query_option", "FOR UPDATE").
				Where("app_id = ? AND seq_type = ?", appID, seqType).
				First(&seq).Error
		}
		return nil
	})
	if err != nil {
		return 0, err
	}

	// 自增
	newVal := seq.CurrentValue + uint64(seq.Step)
	if err := r.db.WithContext(ctx).Model(&model.OrderSequence{}).
		Where("id = ?", seq.ID).
		Update("current_value", newVal).Error; err != nil {
		return 0, err
	}
	return newVal, nil
}

func defaultPrefix(t model.SeqType) string {
	switch t {
	case model.SeqTypeTrade:
		return "PAY"
	case model.SeqTypeRefund:
		return "REF"
	case model.SeqTypeSharing:
		return "SHA"
	default:
		return "ORD"
	}
}

// GetPrefix 获取序列前缀
func (r *SequenceRepository) GetPrefix(ctx context.Context, appID string, seqType model.SeqType) (string, error) {
	var seq model.OrderSequence
	err := r.db.WithContext(ctx).Where("app_id = ? AND seq_type = ?", appID, seqType).First(&seq).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return fmt.Sprintf("%s", defaultPrefix(seqType)), nil
	}
	if err != nil {
		return "", err
	}
	return seq.Prefix, nil
}