// Package lottery implements the user-side lottery HTTP endpoints:
//   GET /api/v1/lottery/config
//   POST /api/v1/lottery/draw
//   GET /api/v1/lottery/records
//   POST /api/v1/lottery/claim (Stage 1: returns 4010 not_claimable)
package lottery

import (
	"context"
	"encoding/json"
	"strings"

	"github.com/perfect-panel/server/internal/logic/lottery/draw"
	modelLottery "github.com/perfect-panel/server/internal/model/lottery"
	userModel "github.com/perfect-panel/server/internal/model/user"
	"github.com/perfect-panel/server/internal/svc"
	"github.com/perfect-panel/server/internal/types"
	"github.com/perfect-panel/server/pkg/constant"
	"github.com/perfect-panel/server/pkg/logger"
	"github.com/perfect-panel/server/pkg/xerr"
	"github.com/pkg/errors"
	"gorm.io/gorm"
)

// currentUserId 取 middleware.AuthMiddleware 注入的 user 上下文。
// 匿名 / 未登录返回 0；handler 侧应当由 AuthMiddleware 已经拦截。
func currentUserId(ctx context.Context) int64 {
	u, ok := ctx.Value(constant.CtxKeyUser).(*userModel.User)
	if !ok || u == nil {
		return 0
	}
	return u.Id
}

// ---- GET /config ------------------------------------------------------------

// QueryLotteryConfigLogic 组装活动 + 奖品 + 用户门槛/次数状态。
type QueryLotteryConfigLogic struct {
	logger.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewQueryLotteryConfigLogic(ctx context.Context, svcCtx *svc.ServiceContext) *QueryLotteryConfigLogic {
	return &QueryLotteryConfigLogic{
		Logger: logger.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *QueryLotteryConfigLogic) QueryLotteryConfig(req *types.GetLotteryConfigRequest) (*types.GetLotteryConfigResponse, error) {
	userId := currentUserId(l.ctx)
	if userId == 0 {
		return nil, xerr.NewErrCode(xerr.ErrorTokenInvalid)
	}
	activity, err := l.loadActivity(req.ActivityId)
	if err != nil {
		return nil, err
	}
	prizes, err := l.loadPrizes(req.ActivityId)
	if err != nil {
		return nil, err
	}
	remaining, _ := l.svcCtx.LotteryChance.Query(l.ctx, userId, req.ActivityId)

	resp := &types.GetLotteryConfigResponse{
		Activity: types.LotteryActivityConfig{
			Id:          activity.Id,
			Title:       activity.Title,
			Description: activity.Description,
			StartAt:     activity.StartAt.Unix(),
			EndAt:       activity.EndAt.Unix(),
			Status:      activity.Status,
			GridSize:    activity.GridSize,
		},
		User: types.LotteryUserStatus{
			ChancesRemaining: remaining,
			// Eligible / UnmetReasons 需要 RuleContextBuilder；PR C 里 draw 路径
			// 用真实构造器，config 路径为节省 DB 查询暂只返回次数，前端拿到
			// 未通过时的具体 reason 是在 POST /draw 返回码 100001 里附带的。
			Eligible: true,
		},
	}
	resp.Activity.Prizes = make([]types.LotteryPrizeConfig, 0, len(prizes))
	for _, p := range prizes {
		soldOut := p.RemainingStock.Valid && p.RemainingStock.Int64 <= 0
		resp.Activity.Prizes = append(resp.Activity.Prizes, types.LotteryPrizeConfig{
			Slot:    p.Slot,
			Id:      p.Id,
			Type:    p.Type,
			Name:    p.Name,
			IconUrl: p.IconURL,
			Config:  json.RawMessage(defaultIfEmpty(p.Config)),
			SoldOut: soldOut,
		})
	}
	return resp, nil
}

func (l *QueryLotteryConfigLogic) loadActivity(id int64) (*modelLottery.Activity, error) {
	var activity modelLottery.Activity
	err := l.svcCtx.DB.WithContext(l.ctx).Where("id = ?", id).First(&activity).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, xerr.NewErrCode(xerr.LotteryActivityEnded)
		}
		return nil, errors.Wrap(xerr.NewErrCode(xerr.DatabaseQueryError), err.Error())
	}
	if activity.Status == modelLottery.ActivityStatusEnded {
		return nil, xerr.NewErrCode(xerr.LotteryActivityEnded)
	}
	return &activity, nil
}

func (l *QueryLotteryConfigLogic) loadPrizes(activityId int64) ([]modelLottery.Prize, error) {
	var prizes []modelLottery.Prize
	err := l.svcCtx.DB.WithContext(l.ctx).
		Where("activity_id = ?", activityId).
		Order("slot ASC").
		Find(&prizes).Error
	if err != nil {
		return nil, errors.Wrap(xerr.NewErrCode(xerr.DatabaseQueryError), err.Error())
	}
	return prizes, nil
}

func defaultIfEmpty(s string) string {
	if strings.TrimSpace(s) == "" {
		return "{}"
	}
	return s
}

// ---- POST /draw -------------------------------------------------------------

// DrawLotteryLogic 是 POST /draw 的入口，委托给 draw.Service。
type DrawLotteryLogic struct {
	logger.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewDrawLotteryLogic(ctx context.Context, svcCtx *svc.ServiceContext) *DrawLotteryLogic {
	return &DrawLotteryLogic{
		Logger: logger.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *DrawLotteryLogic) DrawLottery(req *types.DrawLotteryRequest) (*types.DrawLotteryResponse, error) {
	userId := currentUserId(l.ctx)
	if userId == 0 {
		return nil, xerr.NewErrCode(xerr.ErrorTokenInvalid)
	}
	if l.svcCtx.LotteryDrawService == nil {
		return nil, xerr.NewErrCode(xerr.LotteryActivityEnded)
	}
	result, err := l.svcCtx.LotteryDrawService.Draw(l.ctx, draw.Request{
		UserId:      userId,
		ActivityId:  req.ActivityId,
		ClientNonce: req.ClientNonce,
	})
	if err != nil {
		return nil, err
	}
	resp := &types.DrawLotteryResponse{
		DrawId:           result.DrawId,
		IsWin:            result.IsWin,
		ChancesRemaining: result.ChancesRemaining,
		Claim: types.LotteryClaimStatus{
			Required:    result.Claim.Required,
			AutoClaimed: result.Claim.AutoClaimed,
			Message:     result.Claim.Message,
		},
	}
	if result.Prize != nil {
		resp.Prize = &types.DrawnPrize{
			Slot:   result.Prize.Slot,
			Id:     result.Prize.Id,
			Type:   result.Prize.Type,
			Name:   result.Prize.Name,
			Config: result.Prize.Config,
		}
	}
	return resp, nil
}

// ---- GET /records ----------------------------------------------------------

// QueryLotteryRecordsLogic 分页列出当前用户的中奖流水。
type QueryLotteryRecordsLogic struct {
	logger.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewQueryLotteryRecordsLogic(ctx context.Context, svcCtx *svc.ServiceContext) *QueryLotteryRecordsLogic {
	return &QueryLotteryRecordsLogic{
		Logger: logger.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *QueryLotteryRecordsLogic) QueryLotteryRecords(req *types.GetLotteryRecordsRequest) (*types.GetLotteryRecordsResponse, error) {
	userId := currentUserId(l.ctx)
	if userId == 0 {
		return nil, xerr.NewErrCode(xerr.ErrorTokenInvalid)
	}
	page, size := req.Page, req.Size
	if page <= 0 {
		page = 1
	}
	if size <= 0 || size > 200 {
		size = 20
	}
	db := l.svcCtx.DB.WithContext(l.ctx).
		Model(&modelLottery.Draw{}).
		Where("user_id = ?", userId)
	if req.ActivityId > 0 {
		db = db.Where("activity_id = ?", req.ActivityId)
	}
	if state := recordStatusFilter(req.Status); state != "" {
		switch state {
		case "unclaimed":
			db = db.Where("dispatch_state = ?", modelLottery.DispatchStatePendingClaim)
		case "paid":
			db = db.Where("dispatch_state = ?", modelLottery.DispatchStatePaid)
		case "expired":
			db = db.Where("dispatch_state = ?", modelLottery.DispatchStateExpired)
		}
	}
	var total int64
	if err := db.Count(&total).Error; err != nil {
		return nil, errors.Wrap(xerr.NewErrCode(xerr.DatabaseQueryError), err.Error())
	}
	var draws []modelLottery.Draw
	if err := db.Order("drawn_at DESC").Limit(size).Offset((page - 1) * size).Find(&draws).Error; err != nil {
		return nil, errors.Wrap(xerr.NewErrCode(xerr.DatabaseQueryError), err.Error())
	}
	snapshots, err := l.loadPrizeSnapshots(draws)
	if err != nil {
		return nil, err
	}
	resp := &types.GetLotteryRecordsResponse{Total: total, List: make([]types.LotteryRecord, 0, len(draws))}
	for _, d := range draws {
		record := types.LotteryRecord{
			DrawId:        d.Id,
			ActivityId:    d.ActivityId,
			IsWin:         d.IsWin,
			DispatchState: d.DispatchState,
			DrawnAt:       d.DrawnAt.Unix(),
		}
		if snap, ok := snapshots[d.Id]; ok {
			record.Prize = &types.DrawnPrize{
				Slot:   snap.Slot,
				Id:     snap.PrizeId,
				Type:   snap.Type,
				Name:   snap.Name,
				Config: json.RawMessage(defaultIfEmpty(snap.Config)),
			}
		}
		resp.List = append(resp.List, record)
	}
	return resp, nil
}

func (l *QueryLotteryRecordsLogic) loadPrizeSnapshots(draws []modelLottery.Draw) (map[int64]modelLottery.PrizeSnapshot, error) {
	if len(draws) == 0 {
		return nil, nil
	}
	ids := make([]int64, 0, len(draws))
	for _, d := range draws {
		ids = append(ids, d.Id)
	}
	var snaps []modelLottery.PrizeSnapshot
	if err := l.svcCtx.DB.WithContext(l.ctx).Where("draw_id IN ?", ids).Find(&snaps).Error; err != nil {
		return nil, errors.Wrap(xerr.NewErrCode(xerr.DatabaseQueryError), err.Error())
	}
	out := make(map[int64]modelLottery.PrizeSnapshot, len(snaps))
	for _, s := range snaps {
		out[s.DrawId] = s
	}
	return out, nil
}

func recordStatusFilter(s string) string {
	switch strings.ToLower(strings.TrimSpace(s)) {
	case "", "all":
		return ""
	case "unclaimed", "paid", "expired":
		return strings.ToLower(s)
	default:
		return ""
	}
}

// ---- POST /claim ----------------------------------------------------------

// ClaimLotteryPrizeLogic 是 Stage 2 才实装的入口；Stage 1 直接返回 4010。
type ClaimLotteryPrizeLogic struct {
	logger.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewClaimLotteryPrizeLogic(ctx context.Context, svcCtx *svc.ServiceContext) *ClaimLotteryPrizeLogic {
	return &ClaimLotteryPrizeLogic{
		Logger: logger.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *ClaimLotteryPrizeLogic) ClaimLotteryPrize(_ *types.ClaimLotteryPrizeRequest) (*types.ClaimLotteryPrizeResponse, error) {
	if currentUserId(l.ctx) == 0 {
		return nil, xerr.NewErrCode(xerr.ErrorTokenInvalid)
	}
	// Stage 1 不实装人工领奖流程。
	return nil, xerr.NewErrCode(xerr.LotteryNotClaimable)
}