package store

import (
	"fmt"
	"time"
	"unicode/utf8"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"

	"github.com/wangjia/pay/internal/model"
)

// WebhookDeliveryRow is the row type returned by WebhookStore (alias to the model).
type WebhookDeliveryRow = model.WebhookDelivery

type WebhookStore struct{ db *gorm.DB }

func NewWebhookStore(db *gorm.DB) *WebhookStore { return &WebhookStore{db: db} }

// EnqueueDelivery inserts an outbox row; a duplicate (out_trade_no,event_type,refund_id)
// is a no-op (idempotent enqueue) via ON CONFLICT DO NOTHING. refundID is the
// refund's idempotency dimension (payment events pass "").
func (s *WebhookStore) EnqueueDelivery(outTradeNo, bizSystem, eventType, refundID, payload string) error {
	row := model.WebhookDelivery{
		OutTradeNo: outTradeNo, BizSystem: bizSystem, EventType: eventType,
		RefundID: refundID, Payload: payload,
	}
	err := s.db.Clauses(clause.OnConflict{
		Columns:   []clause.Column{{Name: "out_trade_no"}, {Name: "event_type"}, {Name: "refund_id"}},
		DoNothing: true,
	}).Create(&row).Error
	if err != nil {
		return fmt.Errorf("store.EnqueueDelivery: %w", err)
	}
	return nil
}

func (s *WebhookStore) ListUndelivered(limit int) ([]WebhookDeliveryRow, error) {
	if limit <= 0 || limit > 200 {
		limit = 50
	}
	var out []WebhookDeliveryRow
	if err := s.db.Where("delivered = ?", false).Order("id ASC").Limit(limit).Find(&out).Error; err != nil {
		return nil, fmt.Errorf("store.ListUndelivered: %w", err)
	}
	return out, nil
}

func (s *WebhookStore) MarkDelivered(id uint64) error {
	if err := s.db.Model(&model.WebhookDelivery{}).Where("id = ?", id).
		Update("delivered", true).Error; err != nil {
		return fmt.Errorf("store.MarkDelivered: %w", err)
	}
	return nil
}

// truncateUTF8 safely truncates a string to n bytes without splitting UTF-8 runes.
func truncateUTF8(s string, n int) string {
	if len(s) <= n {
		return s
	}
	s = s[:n]
	for len(s) > 0 && !utf8.ValidString(s) {
		s = s[:len(s)-1]
	}
	return s
}

// MarkFailed increments attempts and records the last error, leaving the row
// undelivered for the next retry sweep. Superseded in production by
// ScheduleRetry/MarkDead (退避感知);kept for existing callers/tests.
func (s *WebhookStore) MarkFailed(id uint64, errMsg string) error {
	errMsg = truncateUTF8(errMsg, 255)
	if err := s.db.Model(&model.WebhookDelivery{}).Where("id = ?", id).
		Updates(map[string]any{
			"attempts":   gorm.Expr("attempts + 1"),
			"last_error": errMsg,
		}).Error; err != nil {
		return fmt.Errorf("store.MarkFailed: %w", err)
	}
	return nil
}

// ListDeliverable 取「未投递、未死信、且退避到点(next_attempt_at NULL 或 <= now)」的行。
func (s *WebhookStore) ListDeliverable(now time.Time, limit int) ([]WebhookDeliveryRow, error) {
	if limit <= 0 || limit > 200 {
		limit = 50
	}
	var out []WebhookDeliveryRow
	if err := s.db.
		Where("delivered = ? AND dead = ? AND (next_attempt_at IS NULL OR next_attempt_at <= ?)", false, false, now).
		Order("id ASC").Limit(limit).Find(&out).Error; err != nil {
		return nil, fmt.Errorf("store.ListDeliverable: %w", err)
	}
	return out, nil
}

// ScheduleRetry 记一次失败并排下次重试:attempts+1、last_error、next_attempt_at=nextAt。
func (s *WebhookStore) ScheduleRetry(id uint64, errMsg string, nextAt time.Time) error {
	errMsg = truncateUTF8(errMsg, 255)
	if err := s.db.Model(&model.WebhookDelivery{}).Where("id = ?", id).
		Updates(map[string]any{
			"attempts":        gorm.Expr("attempts + 1"),
			"last_error":      errMsg,
			"next_attempt_at": nextAt,
		}).Error; err != nil {
		return fmt.Errorf("store.ScheduleRetry: %w", err)
	}
	return nil
}

// MarkDead 达最大次数后放弃:attempts+1、dead=true、last_error。行留库供人工/对账排查。
func (s *WebhookStore) MarkDead(id uint64, errMsg string) error {
	errMsg = truncateUTF8(errMsg, 255)
	if err := s.db.Model(&model.WebhookDelivery{}).Where("id = ?", id).
		Updates(map[string]any{
			"attempts":   gorm.Expr("attempts + 1"),
			"dead":       true,
			"last_error": errMsg,
		}).Error; err != nil {
		return fmt.Errorf("store.MarkDead: %w", err)
	}
	return nil
}