package activity

import (
	"context"
	"crypto/rand"
	"crypto/sha256"
	"encoding/json"
	"errors"
	"sort"

	"bindbox-game/internal/repository/mysql/model"

	"gorm.io/gorm"
)

var algoVersion = "v1-hmac-256"

func (s *service) CommitIssueRandom(ctx context.Context, issueID int64) (*IssueRandomCommitment, error) {
	// 检查活动期数状态
	issue, err := s.readDB.ActivityIssues.WithContext(ctx).
		Where(s.readDB.ActivityIssues.ID.Eq(issueID)).
		First()
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, errors.New("活动期数不存在")
		}
		return nil, err
	}

	// 只允许在未开始状态(3)生成承诺
	if issue.Status != 3 {
		return nil, errors.New("只能在期数未开始状态下生成随机承诺")
	}

	// 检查是否已存在承诺（防止重复生成）
	existing, _ := s.readDB.IssueRandomCommitments.WithContext(ctx).
		Where(s.readDB.IssueRandomCommitments.IssueID.Eq(issueID)).
		First()
	if existing != nil {
		return nil, errors.New("该期数已存在随机承诺，不可重复生成")
	}

	items, err := s.readDB.ActivityRewardSettings.WithContext(ctx).
		Where(s.readDB.ActivityRewardSettings.IssueID.Eq(issueID)).
		Order(s.readDB.ActivityRewardSettings.ID).
		Find()
	if err != nil {
		return nil, err
	}
	if len(items) == 0 {
		return nil, errors.New("该期数未配置奖励，无法生成随机承诺")
	}
	canonical := make([]ReceiptItem, 0, len(items))
	var weightsTotal int64
	for _, it := range items {
		canonical = append(canonical, ReceiptItem{ID: it.ID, Name: it.Name, Weight: it.Weight, QuantityBefore: it.Quantity})
		if it.Weight > 0 && (it.Quantity == -1 || it.Quantity > 0) {
			weightsTotal += int64(it.Weight)
		}
	}

	// 检查奖池权重是否有效
	if weightsTotal <= 0 {
		return nil, errors.New("奖池配置无效：总权重必须大于0")
	}

	sort.Slice(canonical, func(i, j int) bool { return canonical[i].ID < canonical[j].ID })
	b, _ := json.Marshal(canonical)
	itemsRoot := sha256.Sum256(b)
	master := make([]byte, 32)
	_, _ = rand.Read(master)
	serverHash := sha256.Sum256(master)

	nextVer := int32(1)
	enc, _ := maskSeed(master, issueID, nextVer)
	rec := &model.IssueRandomCommitments{
		IssueID:          issueID,
		AlgoVersion:      algoVersion,
		ServerSeedMaster: enc,
		ServerSeedHash:   serverHash[:],
		ItemsRoot:        itemsRoot[:],
		WeightsTotal:     weightsTotal,
		StateVersion:     nextVer,
	}
	if err := s.writeDB.IssueRandomCommitments.WithContext(ctx).Create(rec); err != nil {
		return nil, err
	}
	return &IssueRandomCommitment{
		AlgoVersion:      rec.AlgoVersion,
		IssueID:          rec.IssueID,
		ServerSeedMaster: rec.ServerSeedMaster,
		ServerSeedHash:   rec.ServerSeedHash,
		ItemsRoot:        rec.ItemsRoot,
		WeightsTotal:     rec.WeightsTotal,
		StateVersion:     rec.StateVersion,
	}, nil
}

func (s *service) GetIssueRandomCommit(ctx context.Context, issueID int64) (*IssueRandomCommitment, error) {
	latest, err := s.readDB.IssueRandomCommitments.WithContext(ctx).
		Where(s.readDB.IssueRandomCommitments.IssueID.Eq(issueID)).
		Order(s.readDB.IssueRandomCommitments.StateVersion.Desc()).
		Take()
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, nil // 没有找到记录是正常的，表示尚未生成承诺
		}
		return nil, err
	}
	return &IssueRandomCommitment{
		AlgoVersion:      latest.AlgoVersion,
		IssueID:          latest.IssueID,
		ServerSeedMaster: latest.ServerSeedMaster,
		ServerSeedHash:   latest.ServerSeedHash,
		ItemsRoot:        latest.ItemsRoot,
		WeightsTotal:     latest.WeightsTotal,
		StateVersion:     latest.StateVersion,
	}, nil
}

func (s *service) GetIssueRandomCommitHistory(ctx context.Context, issueID int64) ([]*IssueRandomCommitment, error) {
	commitments, err := s.readDB.IssueRandomCommitments.WithContext(ctx).
		Where(s.readDB.IssueRandomCommitments.IssueID.Eq(issueID)).
		Order(s.readDB.IssueRandomCommitments.StateVersion.Desc()).
		Find()
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			return []*IssueRandomCommitment{}, nil // 返回空数组而不是错误
		}
		return nil, err
	}

	result := make([]*IssueRandomCommitment, 0, len(commitments))
	for _, commit := range commitments {
		result = append(result, &IssueRandomCommitment{
			AlgoVersion:      commit.AlgoVersion,
			IssueID:          commit.IssueID,
			ServerSeedMaster: commit.ServerSeedMaster,
			ServerSeedHash:   commit.ServerSeedHash,
			ItemsRoot:        commit.ItemsRoot,
			WeightsTotal:     commit.WeightsTotal,
			StateVersion:     commit.StateVersion,
		})
	}
	return result, nil
}