package coinser

import (
	"bytes"
	"context"
	"encoding/csv"
	"strconv"
	"time"
	"videoweb/app/api/proto"
	"videoweb/pub/common/response"
	"videoweb/pub/common/srvdef"
	"videoweb/pub/common/utils"
	"videoweb/pub/models/cointransmod"
	"videoweb/pub/pubdef"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo/options"
)

const (
	// coinTransDefaultPageSize 金币余额明细默认每页数量
	coinTransDefaultPageSize int64 = 10
	// coinTransMaxPageSize 金币余额明细最大每页数量，避免单次请求拉取过多流水
	coinTransMaxPageSize int64 = 100
	// coinTransTypeAll 全部交易
	coinTransTypeAll int64 = 0
	// coinTransTypeRecharge 充值交易
	coinTransTypeRecharge int64 = 1
	// coinTransTypeConsume 消费交易
	coinTransTypeConsume int64 = 2
	// coinTransTypeReward 奖励交易
	coinTransTypeReward int64 = 3
)

var (
	// coinTransListProjection 余额明细只读取列表展示需要的字段，降低Mongo读取成本
	coinTransListProjection = bson.D{
		{Key: cointransmod.FN.CoinTrans.Id, Value: 1},
		{Key: cointransmod.FN.CoinTrans.FlowDir, Value: 1},
		{Key: cointransmod.FN.CoinTrans.TranType, Value: 1},
		{Key: cointransmod.FN.CoinTrans.Amount, Value: 1},
		{Key: cointransmod.FN.CoinTrans.BalanceBefore, Value: 1},
		{Key: cointransmod.FN.CoinTrans.BalanceAfter, Value: 1},
		{Key: cointransmod.FN.CoinTrans.OrderNo, Value: 1},
		{Key: cointransmod.FN.CoinTrans.RelatedId, Value: 1},
		{Key: cointransmod.FN.CoinTrans.Remark, Value: 1},
		{Key: cointransmod.FN.CoinTrans.CreatedAt, Value: 1},
	}

	// coinTransListSort 按交易时间倒序展示余额明细
	coinTransListSort = bson.D{
		{Key: cointransmod.FN.CoinTrans.CreatedAt, Value: -1},
	}

	// coinTransListHint 匹配 coin_trans 的 userId+createdAt 复合索引
	coinTransListHint = bson.D{
		{Key: cointransmod.FN.CoinTrans.UserId, Value: 1},
		{Key: cointransmod.FN.CoinTrans.CreatedAt, Value: -1},
	}
)

// GetCoinTransList 查询当前用户金币余额明细
//
// 只查询当前登录用户的流水，按交易时间倒序分页，pageSize 最大限制为100
func GetCoinTransList(ctx context.Context, userId int64, page, pageSize int64, transType int64) (*response.BasePageResp, *srvdef.SrvErr) {
	if userId <= 0 {
		return nil, srvdef.New(srvdef.ErrUserNotExsit, "", "")
	}
	page, pageSize = normalizeCoinTransPage(page, pageSize)
	filter := bson.M{
		cointransmod.FN.CoinTrans.UserId: userId,
	}
	if err := applyCoinTransTypeFilter(filter, transType); err != nil {
		return nil, err
	}
	total, err := cointransmod.CountCoinTrans(ctx, filter)
	if err != nil {
		return nil, err
	}
	if total <= 0 {
		return &response.BasePageResp{
			TotalCount: 0,
			PageSize:   int(pageSize),
			PageNum:    int(page),
			List:       make([]*proto.CoinTransListItemResp, 0),
		}, nil
	}
	list, err1 := cointransmod.FindManyCoinTrans(ctx, filter, options.Find().
		SetProjection(coinTransListProjection).
		SetSort(coinTransListSort).
		SetHint(coinTransListHint).
		SetSkip((page-1)*pageSize).
		SetLimit(pageSize))
	if err1 != nil {
		return nil, err1
	}
	resp := make([]*proto.CoinTransListItemResp, 0, len(list))
	for _, item := range list {
		resp = append(resp, coinTransToListItemResp(item))
	}
	return &response.BasePageResp{
		TotalCount: total,
		PageSize:   int(pageSize),
		PageNum:    int(page),
		List:       resp,
	}, nil
}

// ExportCoinTrans 导出当前用户金币余额明细CSV
func ExportCoinTrans(ctx context.Context, userId int64, transType int64) ([]byte, string, *srvdef.SrvErr) {
	if userId <= 0 {
		return nil, "", srvdef.New(srvdef.ErrUserNotExsit, "", "")
	}
	filter := bson.M{
		cointransmod.FN.CoinTrans.UserId: userId,
	}
	if err := applyCoinTransTypeFilter(filter, transType); err != nil {
		return nil, "", err
	}
	list, err := cointransmod.FindManyCoinTrans(ctx, filter, options.Find().
		SetProjection(coinTransListProjection).
		SetSort(coinTransListSort).
		SetHint(coinTransListHint))
	if err != nil {
		return nil, "", err
	}
	data, serr := buildCoinTransCSV(list)
	if serr != nil {
		return nil, "", serr
	}
	return data, coinTransExportFileName(transType), nil
}

// buildCoinTransCSV 构建金币流水CSV文件内容
func buildCoinTransCSV(list cointransmod.CoinTransList) ([]byte, *srvdef.SrvErr) {
	var buf bytes.Buffer
	buf.WriteString("\xEF\xBB\xBF")
	writer := csv.NewWriter(&buf)
	if err := writer.Write([]string{"类型", "说明", "时间", "金币变动"}); err != nil {
		return nil, srvdef.New(srvdef.ExcelExportErr, "文件导出错误", "文件导出错误")
	}
	for _, item := range list {
		resp := coinTransToListItemResp(item)
		if resp == nil {
			continue
		}
		if err := writer.Write([]string{
			resp.TranTypeName,
			resp.Title,
			resp.CreatedAt,
			formatCoinTransChange(resp.ChangeAmount),
		}); err != nil {
			return nil, srvdef.New(srvdef.ExcelExportErr, "文件导出错误", "文件导出错误")
		}
	}
	writer.Flush()
	if err := writer.Error(); err != nil {
		return nil, srvdef.New(srvdef.ExcelExportErr, "文件导出错误", "文件导出错误")
	}
	return buf.Bytes(), nil
}

// coinTransExportFileName 生成金币流水导出文件名
func coinTransExportFileName(transType int64) string {
	name := "交易明细"
	switch transType {
	case coinTransTypeRecharge:
		name = "充值明细"
	case coinTransTypeConsume:
		name = "消费明细"
	case coinTransTypeReward:
		name = "奖励明细"
	}
	return name + "_" + time.Now().In(utils.LocBJ).Format("20060102150405") + ".csv"
}

// formatCoinTransChange 格式化金币变动值
func formatCoinTransChange(change int64) string {
	if change > 0 {
		return "+" + strconv.FormatInt(change, 10)
	}
	return strconv.FormatInt(change, 10)
}

// applyCoinTransTypeFilter 按交易明细Tab追加筛选条件
func applyCoinTransTypeFilter(filter bson.M, transType int64) *srvdef.SrvErr {
	switch transType {
	case coinTransTypeAll:
		return nil
	case coinTransTypeRecharge:
		filter[cointransmod.FN.CoinTrans.TranType] = cointransmod.TranTypeCoinRecharge
	case coinTransTypeConsume:
		filter[cointransmod.FN.CoinTrans.FlowDir] = cointransmod.FlowOut
	case coinTransTypeReward:
		filter[cointransmod.FN.CoinTrans.FlowDir] = cointransmod.FlowIn
		filter[cointransmod.FN.CoinTrans.TranType] = bson.M{"$ne": cointransmod.TranTypeCoinRecharge}
	default:
		return srvdef.New(srvdef.ErrParamError, "类型错误", "类型错误")
	}
	return nil
}

// normalizeCoinTransPage 规范化金币流水分页参数
//
// page 小于等于0时按第1页处理；pageSize 未传时使用默认值，超过上限时截断
func normalizeCoinTransPage(page, pageSize int64) (int64, int64) {
	if page <= 0 {
		page = 1
	}
	if pageSize <= 0 {
		pageSize = coinTransDefaultPageSize
	}
	if pageSize > coinTransMaxPageSize {
		pageSize = coinTransMaxPageSize
	}
	return page, pageSize
}

// coinTransToListItemResp 转换金币流水响应项
//
// amount 保持数据库中的正数金额，changeAmount 根据收支方向转换为带正负号的变动金额
func coinTransToListItemResp(item *cointransmod.CoinTrans) *proto.CoinTransListItemResp {
	title := item.Remark
	if title == "" {
		title = item.TranType.Desc()
	}
	changeAmount := item.Amount
	if item.FlowDir == cointransmod.FlowOut {
		changeAmount = -item.Amount
	}
	return &proto.CoinTransListItemResp{
		Id:            item.Id,
		Title:         title,
		FlowDir:       item.FlowDir,
		FlowDirName:   item.FlowDir.Desc(),
		TranType:      item.TranType,
		TranTypeName:  item.TranType.Desc(),
		Amount:        item.Amount,
		ChangeAmount:  changeAmount,
		BalanceBefore: item.BalanceBefore,
		BalanceAfter:  item.BalanceAfter,
		OrderNo:       item.OrderNo,
		RelatedId:     item.RelatedId,
		Remark:        item.Remark,
		CreatedAt:     formatCoinTransTime(item.CreatedAt),
	}
}

func formatCoinTransTime(t time.Time) string {
	if t.IsZero() {
		return ""
	}
	return t.In(utils.LocBJ).Format(pubdef.TimeISO)
}