package service

import (
	"context"
	"database/sql"
	"electricity_bill_calc/cache"
	"electricity_bill_calc/config"
	"electricity_bill_calc/exceptions"
	"electricity_bill_calc/global"
	"electricity_bill_calc/logger"
	"electricity_bill_calc/model"
	"fmt"
	"strconv"
	"time"

	"github.com/fufuok/utils"
	"github.com/samber/lo"
	"github.com/uptrace/bun"
	"go.uber.org/zap"
)

type _ChargeService struct {
	l *zap.Logger
}

var ChargeService = _ChargeService{
	l: logger.Named("Service", "Charge"),
}

func (c _ChargeService) CreateChargeRecord(charge *model.UserCharge, extendWithIgnoreSettle bool) error {
	ctx, cancel := global.TimeoutContext()
	defer cancel()
	tx, err := global.DB.BeginTx(ctx, &sql.TxOptions{})
	if err != nil {
		return err
	}
	_, err = tx.NewInsert().Model(charge).Exec(ctx)
	if err != nil {
		tx.Rollback()
		return err
	}
	if extendWithIgnoreSettle {
		err := c.updateUserExpiration(&tx, ctx, charge.UserId, charge.ChargeTo)
		if err != nil {
			return err
		}
	}
	err = tx.Commit()
	if err != nil {
		tx.Rollback()
		return err
	}
	cache.AbolishRelation("charge")
	return nil
}

func (c _ChargeService) SettleCharge(seq int64, uid string) error {
	ctx, cancel := global.TimeoutContext()
	defer cancel()
	tx, err := global.DB.BeginTx(ctx, &sql.TxOptions{})
	if err != nil {
		return err
	}
	var record = new(model.UserCharge)
	err = tx.NewSelect().Model(&record).
		Where("seq = ?", seq).
		Where("user_id = ?", uid).
		Scan(ctx)
	if err != nil {
		return nil
	}
	if record == nil {
		return exceptions.NewNotFoundError("未找到匹配指定条件的计费记录。")
	}
	currentTime := time.Now()
	_, err = tx.NewUpdate().Model((*model.UserCharge)(nil)).
		Where("seq = ?", seq).
		Where("user_id = ?", uid).
		Set("settled = ?", true).
		Set("settled_at = ?", currentTime).
		Exec(ctx)
	if err != nil {
		tx.Rollback()
		return err
	}
	err = c.updateUserExpiration(&tx, ctx, uid, record.ChargeTo)
	if err != nil {
		return err
	}
	err = tx.Commit()
	if err != nil {
		tx.Rollback()
		return err
	}
	cache.AbolishRelation(fmt.Sprintf("charge:%s:%d", uid, seq))
	return nil
}

func (c _ChargeService) RefundCharge(seq int64, uid string) error {
	ctx, cancel := global.TimeoutContext()
	defer cancel()
	tx, err := global.DB.BeginTx(ctx, &sql.TxOptions{})
	if err != nil {
		return err
	}
	currentTime := time.Now()
	res, err := tx.NewUpdate().Model((*model.UserCharge)(nil)).
		Where("seq = ?", seq).
		Where("user_id = ?", uid).
		Set("refunded = ?", true).
		Set("refunded_at = ?", currentTime).
		Exec(ctx)
	if err != nil {
		tx.Rollback()
		return err
	}
	if rows, _ := res.RowsAffected(); rows == 0 {
		tx.Rollback()
		return exceptions.NewNotFoundError("未找到匹配指定条件的计费记录。")
	}
	lastValidExpriation, err := c.lastValidChargeTo(&tx, &ctx, uid)
	if err != nil {
		tx.Rollback()
		return exceptions.NewNotFoundError("未找到最后合法的计费时间。")
	}
	err = c.updateUserExpiration(&tx, ctx, uid, lastValidExpriation)
	if err != nil {
		return err
	}
	err = tx.Commit()
	if err != nil {
		tx.Rollback()
		return err
	}
	cache.AbolishRelation(fmt.Sprintf("charge:%s:%d", uid, seq))
	return nil
}

func (c _ChargeService) CancelCharge(seq int64, uid string) error {
	ctx, cancel := global.TimeoutContext()
	defer cancel()
	tx, err := global.DB.BeginTx(ctx, &sql.TxOptions{})
	if err != nil {
		return err
	}
	currentTime := time.Now()
	res, err := tx.NewUpdate().Model((*model.UserCharge)(nil)).
		Where("seq = ?", seq).
		Where("user_id = ?", uid).
		Set("cancelled = ?", true).
		Set("cancelled_at = ?", currentTime).
		Exec(ctx)
	if err != nil {
		tx.Rollback()
		return err
	}
	if rows, _ := res.RowsAffected(); rows == 0 {
		tx.Rollback()
		return exceptions.NewNotFoundError("未找到匹配指定条件的计费记录。")
	}
	err = tx.Commit()
	if err != nil {
		tx.Rollback()
		return err
	}
	tx, err = global.DB.BeginTx(ctx, &sql.TxOptions{})
	if err != nil {
		return err
	}
	lastValidExpriation, err := c.lastValidChargeTo(&tx, &ctx, uid)
	if err != nil {
		return exceptions.NewNotFoundError("未找到最后合法的计费时间。")
	}
	err = c.updateUserExpiration(&tx, ctx, uid, lastValidExpriation)
	if err != nil {
		return err
	}
	err = tx.Commit()
	if err != nil {
		tx.Rollback()
		return err
	}
	cache.AbolishRelation("user")
	cache.AbolishRelation(fmt.Sprintf("user:%s", uid))
	cache.AbolishRelation("charge")
	cache.AbolishRelation(fmt.Sprintf("charge:%s:%d", uid, seq))
	return nil
}

func (ch _ChargeService) updateUserExpiration(tx *bun.Tx, ctx context.Context, uid string, expiration model.Date) error {
	_, err := tx.NewUpdate().Model((*model.UserDetail)(nil)).
		Set("service_expiration = ?", expiration).
		Where("id = ?", uid).
		Exec(ctx)
	if err != nil {
		tx.Rollback()
	}
	cache.AbolishRelation(fmt.Sprintf("user:%s", uid))
	return err
}

func (_ChargeService) ListPagedChargeRecord(keyword, beginDate, endDate string, page int) ([]model.ChargeWithName, int64, error) {
	var (
		cond      = global.DB.NewSelect()
		condition = make([]string, 0)
		charges   = make([]model.UserCharge, 0)
	)
	cond = cond.Model(&charges).Relation("Detail")
	condition = append(condition, strconv.Itoa(page))
	if len(keyword) != 0 {
		keywordCond := "%" + keyword + "%"
		cond = cond.WhereGroup(" and ", func(q *bun.SelectQuery) *bun.SelectQuery {
			return q.Where("d.mame like ?", keywordCond).
				WhereOr("d.abbr like ?", keywordCond)
		})
		condition = append(condition, keyword)
	}
	if len(beginDate) != 0 {
		beginTime, err := time.ParseInLocation("2006-01-02", beginDate, time.Local)
		beginTime = utils.BeginOfDay(beginTime)
		if err != nil {
			return make([]model.ChargeWithName, 0), 0, err
		}
		cond = cond.Where("c.created_at >= ?", beginTime)
		condition = append(condition, strconv.FormatInt(beginTime.Unix(), 10))
	}
	if len(endDate) != 0 {
		endTime, err := time.ParseInLocation("2006-01-02", endDate, time.Local)
		endTime = utils.EndOfDay(endTime)
		if err != nil {
			return make([]model.ChargeWithName, 0), 0, err
		}
		cond = cond.Where("c.created_at <= ?", endTime)
		condition = append(condition, strconv.FormatInt(endTime.Unix(), 10))
	}

	if cachedTotal, err := cache.RetreiveCount("charge_with_name", condition...); cachedTotal != -1 && err == nil {
		if cachedCharges, _ := cache.RetreiveSearch[[]model.ChargeWithName]("charge_with_name", condition...); cachedCharges != nil {
			return *cachedCharges, cachedTotal, nil
		}
	}

	startItem := (page - 1) * config.ServiceSettings.ItemsPageSize
	var (
		total int
		err   error
	)
	ctx, cancel := global.TimeoutContext()
	defer cancel()
	total, err = cond.Limit(config.ServiceSettings.ItemsPageSize).Offset(startItem).ScanAndCount(ctx)

	relations := []string{"charge"}
	chargesWithName := make([]model.ChargeWithName, 0)
	for _, c := range charges {
		chargesWithName = append(chargesWithName, model.ChargeWithName{
			UserCharge: c,
			UserDetail: *c.Detail,
		})
		relations = append(relations, fmt.Sprintf("charge:%s:%d", c.UserId, c.Seq))
	}

	cache.CacheCount(relations, "charge_with_name", int64(total), condition...)
	cache.CacheSearch(chargesWithName, relations, "charge_with_name", condition...)
	return chargesWithName, int64(total), err
}

func (_ChargeService) lastValidChargeTo(tx *bun.Tx, ctx *context.Context, uid string) (model.Date, error) {
	var records []model.Date
	err := tx.NewSelect().Table("user_charge").
		Where("settled = ? and cancelled = ? and refunded = ? and user_id = ?", true, false, false, uid).
		Column("charge_to").
		Scan(*ctx, &records)
	if err != nil {
		return model.NewEmptyDate(), nil
	}
	lastValid := lo.Reduce(records, func(acc, elem model.Date, index int) model.Date {
		if elem.Time.After(acc.Time) {
			return elem
		} else {
			return acc
		}
	}, model.NewEmptyDate())
	return lastValid, nil
}