UserPostQueries.php: add user post queries class

inc/Data/PageFetchResult.php

@@ -0,0 +1,15 @@
+<?php
+namespace Vichan\Data;
+
+
+/**
+ * A page of user posts.
+ */
+class PageFetchResult {
+	/**
+	 * @var array[array] Posts grouped by board uri.
+	 */
+	public array $by_uri;
+	public ?string $cursor_prev;
+	public ?string $cursor_next;
+}

inc/Data/UserPostQueries.php

@@ -0,0 +1,115 @@
+<?php
+namespace Vichan\Data;
+
+use Vichan\Functions\Net;
+
+
+/**
+ * Browse user posts
+ */
+class UserPostQueries {
+	private const CURSOR_TYPE_PREV = 'p';
+	private const CURSOR_TYPE_NEXT = 'n';
+
+	private \PDO $pdo;
+
+	public function __construct(\PDO $pdo) {
+		$this->pdo = $pdo;
+	}
+
+	/**
+	 * Fetch a page of user posts.
+	 *
+	 * @param array $board_uris The uris of the boards that should be included.
+	 * @param string $ip The IP of the target user.
+	 * @param integer $page_size The Number of posts that should be fetched.
+	 * @param string|null $cursor The directional cursor to fetch the next or previous page. Null to start from the beginning.
+	 * @return PageFetchResult
+	 */
+	public function fetchPaginatedByIp(array $board_uris, string $ip, int $page_size, ?string $cursor = null): PageFetchResult {
+		// Decode the cursor.
+		if ($cursor !== null) {
+			list($cursor_type, $uri_id_cursor_map) = Net\decode_cursor($cursor);
+		} else {
+			// Defaults if $cursor is an invalid string.
+			$cursor_type = null;
+			$uri_id_cursor_map = [];
+		}
+		$next_cursor_map = [];
+		$prev_cursor_map = [];
+		$rows = [];
+
+		foreach ($board_uris as $uri) {
+			// Extract the cursor relative to the board.
+			$id_cursor = false;
+			if (isset($uri_id_cursor_map[$uri])) {
+				$value = $uri_id_cursor_map[$uri];
+				if (\is_numeric($value)) {
+					$id_cursor = (int)$value;
+				}
+			}
+
+			if ($id_cursor === false) {
+				$query = $this->pdo->prepare(sprintf('SELECT * FROM `posts_%s` WHERE `ip` = :ip ORDER BY `sticky` DESC, `id` DESC LIMIT :limit', $uri));
+				$query->bindValue(':ip', $ip);
+				$query->bindValue(':limit', $page_size + 1, \PDO::PARAM_INT); // Always fetch more.
+				$query->execute();
+				$posts = $query->fetchAll(\PDO::FETCH_ASSOC);
+			} elseif ($cursor_type === self::CURSOR_TYPE_NEXT) {
+				$query = $this->pdo->prepare(sprintf('SELECT * FROM `posts_%s` WHERE `ip` = :ip AND `id` <= :start_id ORDER BY `sticky` DESC, `id` DESC LIMIT :limit', $uri));
+				$query->bindValue(':ip', $ip);
+				$query->bindValue(':start_id', $id_cursor, \PDO::PARAM_INT);
+				$query->bindValue(':limit', $page_size + 2, \PDO::PARAM_INT); // Always fetch more.
+				$query->execute();
+				$posts = $query->fetchAll(\PDO::FETCH_ASSOC);
+			} elseif ($cursor_type === self::CURSOR_TYPE_PREV) {
+				$query = $this->pdo->prepare(sprintf('SELECT * FROM `posts_%s` WHERE `ip` = :ip AND `id` >= :start_id ORDER BY `sticky` ASC, `id` ASC LIMIT :limit', $uri));
+				$query->bindValue(':ip', $ip);
+				$query->bindValue(':start_id', $id_cursor, \PDO::PARAM_INT);
+				$query->bindValue(':limit', $page_size + 2, \PDO::PARAM_INT); // Always fetch more.
+				$query->execute();
+				$posts = \array_reverse($query->fetchAll(\PDO::FETCH_ASSOC));
+			} else {
+				throw new \RuntimeException("Unknown cursor type '$cursor_type'");
+			}
+
+			$posts_count = \count($posts);
+
+			if ($posts_count === $page_size + 2) {
+				$has_extra_prev_post = true;
+				$has_extra_end_post = true;
+			} elseif ($posts_count === $page_size + 1) {
+				$has_extra_prev_post = $id_cursor !== false && $id_cursor === (int)$posts[0]['id'];
+				$has_extra_end_post = !$has_extra_prev_post;
+			} else {
+				$has_extra_prev_post = false;
+				$has_extra_end_post = false;
+			}
+
+			// Since we fetched one post bellow and/or above the limit, we always know if there are any posts after the current page.
+
+			// Get the previous cursor, if any.
+			if ($has_extra_prev_post) {
+				\array_shift($posts);
+				$posts_count--;
+				// Select the most recent post.
+				$prev_cursor_map[$uri] = $posts[0]['id'];
+			}
+			// Get the next cursor, if any.
+			if ($has_extra_end_post) {
+				\array_pop($posts);
+				// Select the oldest post.
+				$next_cursor_map[$uri] = $posts[$posts_count - 2]['id'];
+			}
+
+			$rows[$uri] = $posts;
+		}
+
+		$res = new PageFetchResult();
+		$res->by_uri = $rows;
+		$res->cursor_prev = !empty($prev_cursor_map) ? Net\encode_cursor(self::CURSOR_TYPE_PREV, $prev_cursor_map) : null;
+		$res->cursor_next = !empty($next_cursor_map) ? Net\encode_cursor(self::CURSOR_TYPE_NEXT, $next_cursor_map) : null;
+
+		return $res;
+	}
+}