package message

import (
	"database/sql"

	"git.asio.asia/nixevol/NixMsg/internal/protocol"
)

// dispatchMinimalTx 是 M1 最小分发：单聊插一条 pending；群按当前成员去掉发送者各插 pending；
// 消息改为 dispatched。完整 7.4 规则见 DEVIATIONS「消息 M」。
func dispatchMinimalTx(tx *sql.Tx, seq int64, senderID, destKind, destID string, sendAt int64, keep int, nowMs int64) (string, error) {
	recipients := make([]string, 0, 8)
	switch destKind {
	case protocol.TargetEndpoint:
		recipients = append(recipients, destID)
	case protocol.TargetGroup:
		rows, err := tx.Query(`
SELECT endpoint_id FROM group_members WHERE group_id = ? AND endpoint_id != ?`, destID, senderID)
		if err != nil {
			return "", err
		}
		defer func() { _ = rows.Close() }()
		for rows.Next() {
			var id string
			if err := rows.Scan(&id); err != nil {
				return "", err
			}
			recipients = append(recipients, id)
		}
		if err := rows.Err(); err != nil {
			return "", err
		}
	default:
		return "", errCode(protocol.CodeBadRequest, "invalid dest_kind")
	}

	for _, ep := range recipients {
		if _, err := tx.Exec(`
INSERT INTO deliveries(seq, endpoint_id, send_at, keep, state, reason, expire_at, pushed_conn, pushed_at, attempts, updated_at)
VALUES(?,?,?,?,?,?,NULL,NULL,NULL,0,?)`,
			seq, ep, sendAt, keep, DeliveryPending, "", nowMs,
		); err != nil {
			return "", err
		}
	}

	state := StateDispatched
	if _, err := tx.Exec(`UPDATE messages SET state = ? WHERE seq = ?`, state, seq); err != nil {
		return "", err
	}
	return state, nil
}