<?php
namespace FeedReaderCentral;

use SQLite3;
use SQLite3Result;
use SQLite3Stmt;

/**
 * A list of items to be displayed
 *
 * This is a wrapper for retrieval and display of arbitrary lists of items based on a SQLite result.
 */
class ItemList {

    /** @var SQLite3Result The list of items to be displayed */
    private SQLite3Result $items;

    /** @var string The error message generated by executing a query */
    public string $error = '';

    /**
     * Is there an error condition associated with this list?
     *
     * @return bool True if there is an error condition associated with this list, false if not
     */
    public function isError(): bool {
        return $this->error != '';
    }

    /** @var bool Whether to render a link to the feed to which the item belongs */
    public bool $linkFeed = false;

    /** @var bool Whether to display the feed to which the item belongs */
    public bool $displayFeed = false;

    /** @var bool Whether to show read / bookmarked indicators on posts */
    public bool $showIndicators = false;

    /**
     * Constructor
     *
     * @param SQLite3 $db The database connection (used to retrieve error information if the query fails)
     * @param SQLite3Stmt $query The query to retrieve the items for this list
     * @param string $itemType The type of item being displayed (unread, bookmark, etc.)
     * @param string $returnURL The URL to which the item page should return once the item has been viewed
     */
    private function __construct(SQLite3 $db, SQLite3Stmt $query, public string $itemType, public string $returnURL = '')
    {
        $result = $query->execute();
        if (!$result) {
            $this->error = 'SQLite error: ' . $db->lastErrorMsg();
        } else {
            $this->items = $result;
        }
    }

    /**
     * Create an item list query
     *
     * @param SQLite3 $db The database connection to use to obtain items
     * @param array $criteria One or more SQL WHERE conditions (will be combined with AND)
     * @param array $parameters Parameters to be added to the query (key index 0, value index 1; optional)
     * @return SQLite3Stmt The query, ready to be executed
     */
    private static function makeQuery(SQLite3 $db, array $criteria, array $parameters = []): SQLite3Stmt
    {
        $where = empty($criteria) ? '' : 'AND ' . implode(' AND ', $criteria);
        $sql   = <<<SQL
        SELECT item.id, item.feed_id, item.title AS item_title, coalesce(item.updated_on, item.published_on) AS as_of,
               item.is_read, item.is_bookmarked, feed.title AS feed_title
        FROM item INNER JOIN feed ON feed.id = item.feed_id
        WHERE feed.user_id = :userId $where
        ORDER BY coalesce(item.updated_on, item.published_on) DESC
        SQL;
        $query = $db->prepare($sql);
        $query->bindValue(':userId', $_SESSION[Key::USER_ID]);
        foreach ($parameters as $param) $query->bindValue($param[0], $param[1]);
        return $query;
    }

    /**
     * Create an item list with all the current user's bookmarked items
     *
     * @param SQLite3 $db The database connection to use to obtain items
     * @return static An item list with all bookmarked items
     */
    public static function allBookmarked(SQLite3 $db): static
    {
        $list = new static($db, self::makeQuery($db, ['item.is_bookmarked = 1']), 'Bookmarked', '/?bookmarked');
        $list->linkFeed = true;
        return $list;
    }

    /**
     * Create an item list with all the current user's unread items
     *
     * @param SQLite3 $db The database connection to use to obtain items
     * @return static An item list with all unread items
     */
    public static function allUnread(SQLite3 $db): static
    {
        $list = new static($db, self::makeQuery($db, ['item.is_read = 0']), 'Unread');
        $list->linkFeed = true;
        return $list;
    }

    /**
     * Create an item list with all items for the given feed
     *
     * @param int $feedId The ID of the feed for which items should be retrieved
     * @param SQLite3 $db The database connection to use to obtain items
     * @return static An item list with all items for the given feed
     */
    public static function allForFeed(int $feedId, SQLite3 $db): static
    {
        $list = new static($db, self::makeQuery($db, ['feed.id = :feed'], [[':feed', $feedId]]), '',
            "/feed/items?id=$feedId");
        $list->showIndicators = true;
        return $list;
    }

    /**
     * Create an item list with unread items for the given feed
     *
     * @param int $feedId The ID of the feed for which items should be retrieved
     * @param SQLite3 $db The database connection to use to obtain items
     * @return static An item list with unread items for the given feed
     */
    public static function unreadForFeed(int $feedId, SQLite3 $db): static
    {
        return new static($db, self::makeQuery($db, ['feed.id = :feed', 'item.is_read = 0'], [[':feed', $feedId]]),
            'Unread', "/feed/items?id=$feedId&unread");
    }

    /**
     * Create an item list with bookmarked items for the given feed
     *
     * @param int $feedId The ID of the feed for which items should be retrieved
     * @param SQLite3 $db The database connection to use to obtain items
     * @return static An item list with bookmarked items for the given feed
     */
    public static function bookmarkedForFeed(int $feedId, SQLite3 $db): static
    {
        return new static($db,
            self::makeQuery($db, ['feed.id = :feed', 'item.is_bookmarked = 1'], [[':feed', $feedId]]), 'Bookmarked',
            "/feed/items?id=$feedId&bookmarked");
    }

    /**
     * Create an item list with items matching given search terms
     *
     * @param string $search The item search terms / query
     * @param bool $isBookmarked Whether to restrict the search to bookmarked items
     * @param SQLite3 $db The database connection to use to obtain items
     * @return static An item list match the given search terms
     */
    public static function matchingSearch(string $search, bool $isBookmarked, SQLite3 $db): static
    {
        $where   = $isBookmarked ? ['item.is_bookmarked = 1'] : [];
        $where[] = 'item.id IN (SELECT ROWID FROM item_search WHERE content MATCH :search)';
        $list = new static($db, self::makeQuery($db, $where, [[':search', $search]]),
            'Matching' . ($isBookmarked ? ' Bookmarked' : ''),
            "/search?search=$search&items=" . ($isBookmarked ? 'bookmarked' : 'all'));
        $list->showIndicators = true;
        $list->displayFeed    = true;
        return $list;
    }

    /**
     * Render this item list
     */
    public function render(): void
    {
        if ($this->isError()) { ?>
            <p>Error retrieving list:<br><?=$this->error?><?php
            return;
        }
        $item = $this->items->fetchArray(SQLITE3_ASSOC);
        $return = $this->returnURL == '' ? '' : '&from=' . urlencode($this->returnURL);
        echo '<article>';
        if ($item) {
            while ($item) { ?>
                <p><?=hx_get("/item?id={$item['id']}$return", strip_tags($item['item_title']))?><br>
                <small><?php
                    if ($this->showIndicators) {
                        if (!$item['is_read']) echo '<strong>Unread</strong> &nbsp; ';
                        if ($item['is_bookmarked']) echo '<strong>Bookmarked</strong> &nbsp; ';
                    }
                    echo '<em>' . date_time($item['as_of']) . '</em>';
                    if ($this->linkFeed) {
                        echo ' &bull; ' .
                            hx_get("/feed/items?id={$item['feed_id']}&" . strtolower($this->itemType),
                                htmlentities($item['feed_title']));
                    } elseif ($this->displayFeed) {
                        echo ' &bull; ' . htmlentities($item['feed_title']);
                    } ?>
                </small><?php
                $item = $this->items->fetchArray(SQLITE3_ASSOC);
            }
        } else { ?>
            <p><em>There are no <?=strtolower($this->itemType)?> items</em><?php
        }
        echo '</article>';
    }
}