package invite

import (
	"chatapp3-golang/internal/model"
	"chatapp3-golang/internal/utils"
	"context"
	"errors"
	"fmt"
	"time"

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

// ClaimTask 处理邀请任务奖励领取请求。
func (s *InviteService) ClaimTask(ctx context.Context, user AuthUser, req TaskClaimRequest) (*TaskClaimResponse, error) {
	if req.RuleID == 0 {
		return nil, NewAppError(400, "invalid_rule_id", "ruleId is required")
	}
	bundle, err := s.loadBundle(ctx, user.SysOrigin)
	if err != nil {
		return nil, err
	}
	rule := findRuleByID(bundle.Rules, req.RuleID)
	if rule == nil || !rule.Enabled {
		return nil, NewAppError(404, "rule_not_found", "rule not found")
	}
	if rule.RuleType != ruleTypeInviterValidCount && rule.RuleType != ruleTypeInviterTotalRecharge {
		return nil, NewAppError(400, "invalid_rule_type", "rule cannot be claimed manually")
	}

	monthKey := monthKeyAt(time.Now(), normalizeTimezone(bundle.Config.Timezone))
	claimed, err := s.hasTaskClaim(ctx, user.SysOrigin, user.UserID, monthKey, rule.ID)
	if err != nil {
		return nil, err
	}
	monthly, err := s.findMonthlyProgress(ctx, user.SysOrigin, user.UserID, monthKey)
	if err != nil {
		return nil, err
	}
	progressValue := monthly.TotalRecharge
	if rule.RuleType == ruleTypeInviterValidCount {
		progressValue = monthly.InviteCount
	}
	if claimed {
		return &TaskClaimResponse{
			Claimed:        true,
			AlreadyClaimed: true,
			RuleID:         rule.ID,
			RuleType:       rule.RuleType,
			Progress:       progressValue,
			Threshold:      rule.ThresholdValue,
			Reward:         rewardFromRule(rule),
		}, nil
	}
	if progressValue < rule.ThresholdValue {
		return nil, NewAppError(400, "task_not_reached", "task threshold not reached")
	}

	// 先发奖，再落领取记录；发奖侧通过 businessKey 兜底幂等。
	_, err = s.dispatchReward(ctx, rewardDispatchInput{
		SysOrigin:     user.SysOrigin,
		MonthKey:      monthKey,
		InviterUserID: refInt64(user.UserID),
		TargetUserID:  user.UserID,
		Reward:        rewardFromRule(rule),
		Scene:         rule.RuleType,
		RuleID:        refInt64(rule.ID),
		BusinessKey:   fmt.Sprintf("claim:%d:%s:%d", user.UserID, monthKey, rule.ID),
		GoldOrigin:    mapGoldOrigin(rule.RuleType),
		PropsOrigin:   mapPropsOrigin(rule.RuleType),
		Remark:        "resident invite monthly task reward",
	})
	if err != nil {
		return nil, err
	}

	now := time.Now()
	err = s.repo.DB.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := s.createTaskClaimIfAbsentTx(tx, user.SysOrigin, user.UserID, monthKey, rule.ID, now); err != nil {
			return err
		}
		return nil
	})
	if err != nil {
		return nil, err
	}

	return &TaskClaimResponse{
		Claimed:        true,
		AlreadyClaimed: false,
		RuleID:         rule.ID,
		RuleType:       rule.RuleType,
		Progress:       progressValue,
		Threshold:      rule.ThresholdValue,
		Reward:         rewardFromRule(rule),
	}, nil
}

// hasTaskClaim 判断任务是否已经被领取。
func (s *InviteService) hasTaskClaim(ctx context.Context, sysOrigin string, inviterUserID int64, monthKey string, ruleID int64) (bool, error) {
	var count int64
	err := s.repo.DB.WithContext(ctx).
		Model(&model.InviteCampaignTaskClaim{}).
		Where("sys_origin = ? AND inviter_user_id = ? AND month_key = ? AND rule_id = ?", sysOrigin, inviterUserID, monthKey, ruleID).
		Count(&count).Error
	return count > 0, err
}

// incrementMonthlyProgressTx 在事务里更新月度进度。
func (s *InviteService) incrementMonthlyProgressTx(tx *gorm.DB, sysOrigin string, inviterUserID int64, monthKey string, mutate func(item *model.InviteCampaignMonthlyProgress)) error {
	var progress model.InviteCampaignMonthlyProgress
	err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).
		Where("sys_origin = ? AND inviter_user_id = ? AND month_key = ?", sysOrigin, inviterUserID, monthKey).
		First(&progress).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		id, idErr := utils.NextID()
		if idErr != nil {
			return idErr
		}
		now := time.Now()
		progress = model.InviteCampaignMonthlyProgress{
			ID:            id,
			SysOrigin:     sysOrigin,
			InviterUserID: inviterUserID,
			MonthKey:      monthKey,
			CreateTime:    now,
			UpdateTime:    now,
		}
		mutate(&progress)
		return tx.Create(&progress).Error
	}
	if err != nil {
		return err
	}
	mutate(&progress)
	progress.UpdateTime = time.Now()
	return tx.Save(&progress).Error
}

// createTaskClaimIfAbsentTx 在事务里创建领取记录，避免重复领取。
func (s *InviteService) createTaskClaimIfAbsentTx(tx *gorm.DB, sysOrigin string, inviterUserID int64, monthKey string, ruleID int64, claimTime time.Time) error {
	var existing model.InviteCampaignTaskClaim
	err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).
		Where("sys_origin = ? AND inviter_user_id = ? AND month_key = ? AND rule_id = ?", sysOrigin, inviterUserID, monthKey, ruleID).
		First(&existing).Error
	if err == nil {
		return nil
	}
	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return err
	}
	id, idErr := utils.NextID()
	if idErr != nil {
		return idErr
	}
	return tx.Create(&model.InviteCampaignTaskClaim{
		ID:            id,
		SysOrigin:     sysOrigin,
		InviterUserID: inviterUserID,
		MonthKey:      monthKey,
		RuleID:        ruleID,
		ClaimTime:     claimTime,
		CreateTime:    claimTime,
		UpdateTime:    claimTime,
	}).Error
}