package livechat

import (
	"context"
	"errors"
	"time"

	"gorm.io/gorm"

	biz "kra/internal/biz/livechat"
)

type Provider interface{ DB() *gorm.DB }

type repo struct{ data Provider }

func NewRepo(data Provider) biz.Repo { return &repo{data: data} }

type messagePO struct {
	ID           uint   `gorm:"primaryKey"`
	RoomID       uint   `gorm:"index"`
	Type         string `gorm:"size:20;index"`
	UserID       uint   `gorm:"index"`
	Username     string `gorm:"size:120"`
	Nickname     string `gorm:"size:120"`
	Avatar       string `gorm:"size:1000"`
	Content      string `gorm:"size:255"`
	GiftID       uint
	GiftName     string `gorm:"size:60"`
	GiftIcon     string `gorm:"size:1000"`
	Quantity     int
	DiamondTotal int64
	CreatedAt    time.Time `gorm:"index"`
}

func (messagePO) TableName() string { return "live_chat_messages" }

type userSnapshot struct {
	ID       uint
	Username string
	Nickname string
	Avatar   string
}

func (r *repo) ListRecent(ctx context.Context, roomID uint, limit int) ([]*biz.Message, error) {
	if err := r.ensureRoom(ctx, roomID); err != nil {
		return nil, err
	}
	var rows []messagePO
	if err := r.data.DB().WithContext(ctx).Where("room_id = ?", roomID).Order("id DESC").Limit(limit).Find(&rows).Error; err != nil {
		return nil, err
	}
	out := make([]*biz.Message, 0, len(rows))
	for i := len(rows) - 1; i >= 0; i-- {
		out = append(out, toBiz(&rows[i]))
	}
	return out, nil
}

func (r *repo) CreateChat(ctx context.Context, roomID, userID uint, content string) (*biz.Message, error) {
	if err := r.ensureRoom(ctx, roomID); err != nil {
		return nil, err
	}
	user, err := r.user(ctx, userID)
	if err != nil {
		return nil, err
	}
	row := &messagePO{RoomID: roomID, Type: biz.TypeChat, UserID: user.ID, Username: user.Username, Nickname: user.Nickname, Avatar: user.Avatar, Content: content}
	if err = r.createAndPrune(ctx, row); err != nil {
		return nil, err
	}
	return toBiz(row), nil
}

func (r *repo) CreateGift(ctx context.Context, gift *biz.GiftSnapshot) (*biz.Message, error) {
	if err := r.ensureRoom(ctx, gift.RoomID); err != nil {
		return nil, err
	}
	user, err := r.user(ctx, gift.UserID)
	if err != nil {
		return nil, err
	}
	username, nickname := gift.Username, gift.Nickname
	if username == "" {
		username = user.Username
	}
	if nickname == "" {
		nickname = user.Nickname
	}
	row := &messagePO{RoomID: gift.RoomID, Type: biz.TypeGift, UserID: gift.UserID, Username: username, Nickname: nickname, Avatar: user.Avatar, GiftID: gift.GiftID, GiftName: gift.GiftName, GiftIcon: gift.GiftIcon, Quantity: gift.Quantity, DiamondTotal: gift.DiamondTotal}
	if err = r.createAndPrune(ctx, row); err != nil {
		return nil, err
	}
	return toBiz(row), nil
}

func (r *repo) createAndPrune(ctx context.Context, row *messagePO) error {
	return r.data.DB().WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := tx.Create(row).Error; err != nil {
			return err
		}
		var boundary messagePO
		err := tx.Select("id").Where("room_id = ?", row.RoomID).Order("id DESC").Offset(99).Limit(1).Take(&boundary).Error
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil
		}
		if err != nil {
			return err
		}
		return tx.Where("room_id = ? AND id < ?", row.RoomID, boundary.ID).Delete(&messagePO{}).Error
	})
}

func (r *repo) ensureRoom(ctx context.Context, roomID uint) error {
	var count int64
	if err := r.data.DB().WithContext(ctx).Table("live_rooms").Where("id = ? AND deleted_at IS NULL AND enabled = ?", roomID, true).Count(&count).Error; err != nil {
		return err
	}
	if count == 0 {
		return biz.ErrRoomNotFound
	}
	return nil
}

func (r *repo) user(ctx context.Context, userID uint) (*userSnapshot, error) {
	var row userSnapshot
	if err := r.data.DB().WithContext(ctx).Table("sys_users").Select("id, username, nick_name AS nickname, header_img AS avatar").Where("id = ? AND deleted_at IS NULL AND enable = ?", userID, 1).Scan(&row).Error; err != nil {
		return nil, err
	}
	if row.ID == 0 {
		return nil, biz.ErrUserNotFound
	}
	return &row, nil
}

func toBiz(row *messagePO) *biz.Message {
	return &biz.Message{ID: row.ID, RoomID: row.RoomID, Type: row.Type, UserID: row.UserID, Username: row.Username, Nickname: row.Nickname, Avatar: row.Avatar, Content: row.Content, GiftID: row.GiftID, GiftName: row.GiftName, GiftIcon: row.GiftIcon, Quantity: row.Quantity, DiamondTotal: row.DiamondTotal, CreatedAt: row.CreatedAt}
}