package refund

import (
	"context"
	stderrors "errors"
	"strconv"
	"time"

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

	"github.com/break/junhong_cmp_fiber/internal/infrastructure/audit"
	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/internal/model/dto"
	"github.com/break/junhong_cmp_fiber/pkg/auditcontext"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
	"github.com/break/junhong_cmp_fiber/pkg/middleware"
)

// assetPostErrorMessageMax 是尝试记录与退款单上错误摘要的最大长度（字符）。
const assetPostErrorMessageMax = 500

// ProcessAssetPostProcessing 是 Outbox 投递（含补偿扫描重投）的退款资产后处理入口。
// 后处理失败只更新重试状态并返回 nil，由补偿扫描按下次重试时间拉起，不靠 Outbox 自身重投；
// 只有读写退款单本身失败时返回错误，交给 Outbox 重试。
func (s *Service) ProcessAssetPostProcessing(ctx context.Context, refundID uint) error {
	return s.runAssetPostProcessing(ctx, refundID, constants.RefundPostTriggerOutbox)
}

// RetryAssetPostProcessingByAdmin 是后台人工重试接口：仅平台账号，按详情可见范围定位后重试并返回最新详情。
func (s *Service) RetryAssetPostProcessingByAdmin(ctx context.Context, refundID uint) (*dto.RefundResponse, error) {
	userType := middleware.GetUserTypeFromContext(ctx)
	if userType != constants.UserTypeSuperAdmin && userType != constants.UserTypePlatform {
		return nil, errors.New(errors.CodeForbidden, "只有平台账号可以重试退款资产后处理")
	}
	if _, err := s.refundStore.GetByID(ctx, refundID); err != nil {
		return nil, errors.New(errors.CodeNotFound, "退款申请不存在")
	}
	if err := s.RetryAssetPostProcessing(ctx, refundID); err != nil {
		return nil, err
	}
	return s.GetByID(ctx, refundID)
}

// RetryAssetPostProcessing 是人工重试入口，只允许对"需人工处理"的退款单发起。
func (s *Service) RetryAssetPostProcessing(ctx context.Context, refundID uint) error {
	var refund model.RefundRequest
	if err := s.db.WithContext(ctx).Select("id", "status", "asset_reset", "asset_post_status").First(&refund, refundID).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return errors.New(errors.CodeNotFound, "退款单不存在")
		}
		return errors.Wrap(errors.CodeDatabaseError, err, "查询退款单失败")
	}
	if refund.AssetReset || refund.AssetPostStatus != model.RefundAssetPostManualRequired {
		return errors.New(errors.CodeInvalidStatus, "只有需人工处理的退款单可以重试资产后处理")
	}
	if err := s.runAssetPostProcessing(ctx, refundID, constants.RefundPostTriggerManual); err != nil {
		return err
	}
	if err := s.db.WithContext(ctx).Select("asset_reset", "asset_post_last_error").First(&refund, refundID).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "复核退款资产后处理状态失败")
	}
	if !refund.AssetReset {
		return errors.New(errors.CodeServiceUnavailable, "资产后处理仍未完成："+refund.AssetPostLastError)
	}
	return nil
}

func (s *Service) runAssetPostProcessing(ctx context.Context, refundID uint, trigger string) error {
	var refund model.RefundRequest
	if err := s.db.WithContext(ctx).Where("id = ?", refundID).First(&refund).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "查询退款单失败")
	}
	if refund.AssetReset {
		return nil
	}
	now := time.Now()
	if trigger == constants.RefundPostTriggerOutbox {
		if refund.AssetPostStatus == model.RefundAssetPostManualRequired {
			return nil
		}
		if refund.AssetPostNextAt != nil && refund.AssetPostNextAt.After(now) {
			return nil
		}
		ctx = auditcontext.With(ctx, auditcontext.Context{
			ActorKind: constants.AuditActorSystemTask, ActorID: constants.AuditActorIDRefundAssetPostProcessing,
			ActorName: "退款资产自动后处理任务", Source: constants.AuditSourceWorker, CorrelationID: refund.RefundNo,
		})
	}

	// 先占用本次尝试序号，使完成审计能读到总尝试次数。
	attempt := refund.AssetPostAttempts + 1
	if err := s.db.WithContext(ctx).Model(&model.RefundRequest{}).Where("id = ?", refundID).
		Update("asset_post_attempts", attempt).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "更新退款资产后处理次数失败")
	}
	refund.AssetPostAttempts = attempt

	outcome := s.handleRefundAssetProcessing(ctx, &refund)
	record := s.recordAssetPostAttempt(ctx, &refund, outcome, attempt, trigger, time.Since(now))
	if outcome.Err == nil {
		return s.completeAssetPostProcessing(ctx, refundID)
	}
	return s.failAssetPostProcessing(ctx, &refund, outcome, attempt, trigger, record)
}

func (s *Service) completeAssetPostProcessing(ctx context.Context, refundID uint) error {
	if err := s.db.WithContext(ctx).Model(&model.RefundRequest{}).Where("id = ?", refundID).Updates(map[string]any{
		"asset_post_status": model.RefundAssetPostCompleted, "asset_post_last_error": "", "asset_post_next_at": nil,
	}).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "更新退款资产后处理状态失败")
	}
	return nil
}

func (s *Service) failAssetPostProcessing(
	ctx context.Context, refund *model.RefundRequest, outcome refundAssetOutcome, attempt int, trigger string, record *model.RefundPostProcessAttempt,
) error {
	message := truncateRunes(outcome.Err.Error(), assetPostErrorMessageMax)
	updates := map[string]any{"asset_post_last_error": message}
	final := attempt >= constants.RefundPostMaxAttempts
	if final {
		updates["asset_post_status"] = model.RefundAssetPostManualRequired
		updates["asset_post_next_at"] = nil
	} else {
		updates["asset_post_status"] = model.RefundAssetPostRetryPending
		updates["asset_post_next_at"] = time.Now().Add(assetPostBackoff(attempt))
	}
	if err := s.db.WithContext(ctx).Model(&model.RefundRequest{}).Where("id = ?", refund.ID).Updates(updates).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "更新退款资产后处理重试状态失败")
	}
	s.recordAssetPostFailureAudit(ctx, refund, outcome, attempt, record, final || trigger == constants.RefundPostTriggerManual)
	return nil
}

// recordAssetPostFailureAudit 写后处理失败：中间失败只写应用日志，转人工或人工重试失败写审计结论。
func (s *Service) recordAssetPostFailureAudit(
	ctx context.Context, refund *model.RefundRequest, outcome refundAssetOutcome, attempt int, record *model.RefundPostProcessAttempt, final bool,
) {
	if s.auditWriter == nil || s.db == nil {
		return
	}
	primary := audit.RefundResource(refund, constants.AuditResourceRelationPrimary, constants.AuditResourceRoleRefundTarget)
	primary.SubjectVisibility = constants.AuditSubjectInternalOnly
	input := audit.AppendInput{
		EventID:    "refund:" + strconv.FormatUint(uint64(refund.ID), 10) + ":asset-processed:failed:" + strconv.Itoa(attempt),
		ActionCode: constants.AuditActionRefundAssetProcessed, Summary: "退款资产后处理失败（" + outcome.Step + "）",
		ScopeType: constants.AuditScopePlatform, CorrelationID: refund.RefundNo, Resources: []audit.ResourceInput{primary},
		Final: final, Attempt: attempt,
		Metadata: map[string]any{"asset_post_attempts": attempt, "step": outcome.Step, "manual_required": attempt >= constants.RefundPostMaxAttempts},
	}
	if final {
		input.Summary = "退款资产后处理重试用尽，转人工处理（" + outcome.Step + "）"
		for key, value := range assetPostOutcomeMetadata(ctx, s.db, refund) {
			input.Metadata[key] = value
		}
	}
	if record != nil && record.ID > 0 {
		input.AttemptRecordID = strconv.FormatUint(uint64(record.ID), 10)
	}
	s.auditWriter.RecordFailure(ctx, s.db, input, outcome.Err)
}

// recordAssetPostAttempt 写一条尝试记录；写入失败只告警，不影响后处理结果。
func (s *Service) recordAssetPostAttempt(
	ctx context.Context, refund *model.RefundRequest, outcome refundAssetOutcome, attempt int, trigger string, duration time.Duration,
) *model.RefundPostProcessAttempt {
	record := &model.RefundPostProcessAttempt{
		RefundID: refund.ID, RefundNo: refund.RefundNo, Step: outcome.Step, AssetType: outcome.AssetType, AssetID: outcome.AssetID,
		Attempt: attempt, Trigger: trigger, Result: constants.RefundPostResultSuccess, DurationMS: int(duration.Milliseconds()),
	}
	if outcome.AssetType == constants.AssetTypeIotCard && outcome.AssetID > 0 {
		var card model.IotCard
		if err := s.db.WithContext(ctx).Select("iccid").First(&card, outcome.AssetID).Error; err == nil {
			record.ICCID = card.ICCID
		}
	}
	if outcome.Err != nil {
		record.Result = constants.RefundPostResultFailed
		record.ErrorCode, record.ErrorMessage = assetPostErrorDetail(outcome.Err)
	}
	if err := s.db.WithContext(ctx).Create(record).Error; err != nil {
		s.logger.Warn("写退款资产后处理尝试记录失败", zap.Uint("refund_id", refund.ID), zap.Int("attempt", attempt), zap.Error(err))
		return nil
	}
	return record
}

// assetPostOutcomeMetadata 返回结论审计需要的总尝试次数、首次失败时间与最后错误。
func assetPostOutcomeMetadata(ctx context.Context, db *gorm.DB, refund *model.RefundRequest) map[string]any {
	metadata := map[string]any{"asset_post_attempts": refund.AssetPostAttempts}
	var first model.RefundPostProcessAttempt
	if err := db.WithContext(ctx).Where("refund_id = ? AND result = ?", refund.ID, constants.RefundPostResultFailed).
		Order("created_at ASC, id ASC").Limit(1).Find(&first).Error; err == nil && first.ID > 0 {
		metadata["first_failed_at"] = first.CreatedAt
	}
	var last model.RefundPostProcessAttempt
	if err := db.WithContext(ctx).Where("refund_id = ? AND result = ?", refund.ID, constants.RefundPostResultFailed).
		Order("created_at DESC, id DESC").Limit(1).Find(&last).Error; err == nil && last.ID > 0 {
		metadata["last_error_code"] = last.ErrorCode
	}
	return metadata
}

// assetPostBackoff 返回第 attempt 次失败后的重试间隔：2^(attempt-1) 分钟，最长 1 小时。
func assetPostBackoff(attempt int) time.Duration {
	if attempt < 1 {
		attempt = 1
	}
	if attempt > 7 {
		return constants.RefundPostMaxBackoff
	}
	delay := time.Duration(1<<(attempt-1)) * time.Minute
	if delay > constants.RefundPostMaxBackoff {
		return constants.RefundPostMaxBackoff
	}
	return delay
}

func assetPostErrorDetail(err error) (string, string) {
	code := strconv.Itoa(errors.CodeInternalError)
	var appErr *errors.AppError
	if stderrors.As(err, &appErr) && appErr != nil {
		code = strconv.Itoa(appErr.Code)
	}
	return code, truncateRunes(err.Error(), assetPostErrorMessageMax)
}

func truncateRunes(value string, limit int) string {
	runes := []rune(value)
	if len(runes) <= limit {
		return value
	}
	return string(runes[:limit])
}