S2OJ/web/app/models/ClickZans.php

<?php

class ClickZans {
	public static function getTable($type) {
		switch ($type) {
			case 'B':
				return 'blogs';
			case 'BC':
				return 'blogs_comments';
			case 'P':
				return 'problems';
			case 'C':
				return 'contests';
		}
		return null;
	}

	public static function canClickZan($id, $type, $user) {
		switch ($type) {
			case 'P':
				return UOJProblem::query($id)->userCanClickZan($user);
			default:
				return true;
		}
	}

	public static function query($id, $type, $user) {
		if ($user == null) {
			return 0;
		}
		$row = DB::selectFirst([
			"select val from click_zans",
			"where", [
				'username' => $user['username'],
				'type' => $type,
				'target_id' => $id
			]
		]);
		if ($row == null) {
			return 0;
		}
		return $row['val'];
	}

	public static function click($id, $type, $user, $delta) {
		if (!DB::$in_transaction) {
			return DB::transaction(fn () => ClickZans::click($id, $type, $user, $delta));
		}

		$table_name = ClickZans::getTable($type);

		$cur = ClickZans::query($id, $type, $user);

		$row = DB::selectFirst([
			"select zan from", DB::table($table_name),
			"where", ['id' => $id], DB::for_update()
		]);
		if (!$row) {
			return '<div class="text-danger">failed</div>';
		}

		if ($cur != $delta) {
			$cur += $delta;
			if ($cur == 0) {
				DB::delete([
					"delete from click_zans",
					"where", [
						'username' => Auth::id(),
						'type' => $type,
						'target_id' => $id
					]
				]);
			} elseif ($cur != $delta) {
				DB::update([
					"update click_zans",
					"set", ['val' => $cur],
					"where", [
						'username' => Auth::id(),
						'type' => $type,
						'target_id' => $id
					]
				]);
			} else {
				DB::insert([
					"insert into click_zans",
					"(username, type, target_id, val)", "values",
					DB::tuple([Auth::id(), $type, $id, $cur])
				]);
			}
			$cnt = $row['zan'] + $delta;
			DB::update([
				"update", DB::table($table_name),
				"set", ['zan' => $cnt],
				"where", ['id' => $id]
			]);
		} else {
			$cnt = $row['zan'];
		}

		return ClickZans::getBlock($type, $id, $cnt, $cur);
	}

	public static function getBlock($type, $id, $cnt, $val = null) {
		if ($val === null) {
			$val = ClickZans::query($id, $type, Auth::user());
		}
		return '<div class="uoj-click-zan-block" data-id="' . $id . '" data-type="' . $type . '" data-val="' . $val . '" data-cnt="' . $cnt . '"></div>';
	}

	public static function getCntBlock($cnt) {
		$cls = 'uoj-click-zan-block-';
		if ($cnt > 0) {
			$cls .= 'positive';
		} elseif ($cnt < 0) {
			$cls .= 'negative';
		} else {
			$cls .= 'neutral';
		}

		$display_cnt = $cnt > 0 ? '+' . $cnt : $cnt;

		if ($cnt < 0) $display_cnt = '-';

		return '<span class="' . $cls . '"><span class="uoj-click-zan-cnt">[<strong>' . $display_cnt . '</strong>]</span></span>';
	}
}