package model

import (
	"context"
	"time"

	"spark-server/internal/module/conversation/entity"
	"spark-server/internal/pkg/errs"
)

// ConversationMember maps table conversation_members.
type ConversationMember struct {
	ID             int64     `gorm:"column:id;primaryKey;autoIncrement;comment:行 id，表内自增，仅内部用；业务唯一键是 (conversation_id, user_id)"`
	ConversationID int64     `gorm:"column:conversation_id;comment:会话 id"`
	UserID         int64     `gorm:"column:user_id;comment:成员 user_id"`
	LastReadMsgID  int64     `gorm:"column:last_read_msg_id;comment:该成员已读到的最大消息 id，未读真相；Redis 丢了可从此重建"`
	JoinedAt       time.Time `gorm:"column:joined_at;comment:加入会话时间"`
	Muted          int       `gorm:"column:muted;comment:0=未静音 1=免打扰"`
}

func (ConversationMember) TableName() string { return "t_conversation_members" }

func (r *ConversationMember) entity() *entity.Member {
	if r == nil {
		return nil
	}
	m := &entity.Member{
		ConversationID: r.ConversationID, UserID: r.UserID,
		LastReadMsgID: r.LastReadMsgID, JoinedAtMS: r.JoinedAt.UnixMilli(),
	}
	m.Muted = r.Muted != 0
	return m
}

func (m *Repo) ListMemberIDs(ctx context.Context, conversationID int64) ([]int64, error) {
	if conversationID <= 0 {
		return nil, errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return nil, err
	}
	var rows []ConversationMember
	if err := db.Where("conversation_id = ?", conversationID).Find(&rows).Error; err != nil {
		return nil, mapDBErr(err)
	}
	ids := make([]int64, 0, len(rows))
	for i := range rows {
		ids = append(ids, rows[i].UserID)
	}
	return ids, nil
}

func (m *Repo) UpdateLastRead(ctx context.Context, conversationID, userID, msgID int64) error {
	if conversationID <= 0 || userID <= 0 || msgID <= 0 {
		return errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return err
	}
	res := db.Model(&ConversationMember{}).
		Where("conversation_id = ? AND user_id = ? AND last_read_msg_id < ?", conversationID, userID, msgID).
		Update("last_read_msg_id", msgID)
	if res.Error != nil {
		return mapDBErr(res.Error)
	}
	if res.RowsAffected > 0 {
		return nil
	}
	var n int64
	if err := db.Model(&ConversationMember{}).
		Where("conversation_id = ? AND user_id = ?", conversationID, userID).
		Count(&n).Error; err != nil {
		return mapDBErr(err)
	}
	if n == 0 {
		return errs.ErrNotFound
	}
	return nil
}

func (m *Repo) DialogFaces(ctx context.Context, viewerID int64, conversationIDs []int64) (map[int64]entity.DialogFace, error) {
	out := map[int64]entity.DialogFace{}
	if len(conversationIDs) == 0 {
		return out, nil
	}
	db, err := m.session(ctx)
	if err != nil {
		return nil, err
	}
	type faceRow struct {
		ID            int64 `gorm:"column:id"`
		Type          int   `gorm:"column:type"`
		UserSmall     int64 `gorm:"column:user_small"`
		UserBig       int64 `gorm:"column:user_big"`
		GroupID       int64 `gorm:"column:group_id"`
		LastReadMsgID int64 `gorm:"column:last_read_msg_id"`
	}
	var rows []faceRow
	err = db.Table("t_conversations AS c").
		Select("c.id, c.type, COALESCE(p.user_small, 0) AS user_small, COALESCE(p.user_big, 0) AS user_big, COALESCE(g.id, 0) AS group_id, COALESCE(mem.last_read_msg_id, 0) AS last_read_msg_id").
		Joins("LEFT JOIN t_p2p_conversations AS p ON p.conversation_id = c.id").
		Joins("LEFT JOIN t_groups AS g ON g.conversation_id = c.id").
		Joins("LEFT JOIN t_conversation_members AS mem ON mem.conversation_id = c.id AND mem.user_id = ?", viewerID).
		Where("c.id IN ?", conversationIDs).
		Scan(&rows).Error
	if err != nil {
		return nil, mapDBErr(err)
	}
	for i := range rows {
		row := rows[i]
		face := entity.DialogFace{
			ConversationID: row.ID, Type: entity.Type(row.Type),
			GroupID: row.GroupID, LastReadMsgID: row.LastReadMsgID,
		}
		if face.Type == entity.TypeP2P {
			switch {
			case row.UserSmall == viewerID:
				face.PeerID = row.UserBig
			case row.UserBig == viewerID:
				face.PeerID = row.UserSmall
			}
		}
		out[row.ID] = face
	}
	return out, nil
}

func (m *Repo) GetMember(ctx context.Context, conversationID, userID int64) (*entity.Member, error) {
	if conversationID <= 0 || userID <= 0 {
		return nil, errs.ErrInvalidArgument
	}
	db, err := m.session(ctx)
	if err != nil {
		return nil, err
	}
	var row ConversationMember
	if err := db.Where("conversation_id = ? AND user_id = ?", conversationID, userID).Take(&row).Error; err != nil {
		return nil, mapDBErr(err)
	}
	return row.entity(), nil
}