<?php
/**
 * A centralized place for data access for the application
 */
class Data {

    /**
     * Obtain a new connection to the database
     * @return SQLite3 A new connection to the database
     */
    public static function getConnection(): SQLite3 {
        $db = new SQLite3(implode(DIRECTORY_SEPARATOR, [__DIR__, '..', 'data', DATABASE_NAME]));
        $db->exec('PRAGMA foreign_keys = ON;');
        return $db;
    }

    /**
     * Make sure the expected tables exist
     */
    public static function ensureDb(): void {
        $db = self::getConnection();
        $tables = array();
        $tableQuery = $db->query("SELECT name FROM sqlite_master WHERE type = 'table'");
        while ($table = $tableQuery->fetchArray(SQLITE3_NUM)) $tables[] = $table[0];
        if (!in_array('frc_user', $tables)) {
            $query = <<<'SQL'
                CREATE TABLE frc_user (
                    id       INTEGER NOT NULL PRIMARY KEY,
                    email    TEXT    NOT NULL,
                    password TEXT    NOT NULL)
                SQL;
            $db->exec($query);
            $db->exec('CREATE INDEX idx_user_email ON frc_user (email)');
        }
        if (!in_array('feed', $tables)) {
            $query = <<<'SQL'
                CREATE TABLE feed (
                    id         INTEGER NOT NULL PRIMARY KEY,
                    user_id    INTEGER NOT NULL,
                    url        TEXT    NOT NULL,
                    title      TEXT,
                    updated_on TEXT,
                    checked_on TEXT,
                    FOREIGN KEY (user_id) REFERENCES frc_user (id))
                SQL;
            $db->exec($query);
        }
        if (!in_array('item', $tables)) {
            $query = <<<'SQL'
                CREATE TABLE item (
                    id            INTEGER NOT NULL PRIMARY KEY,
                    feed_id       INTEGER NOT NULL,
                    title         TEXT    NOT NULL,
                    item_guid     TEXT    NOT NULL,
                    item_link     TEXT    NOT NULL,
                    published_on  TEXT    NOT NULL,
                    updated_on    TEXT,
                    content       TEXT    NOT NULL,
                    is_read       BOOLEAN NOT NULL DEFAULT 0,
                    is_bookmarked BOOLEAN NOT NULL DEFAULT 0,
                    FOREIGN KEY (feed_id) REFERENCES feed (id))
                SQL;
            $db->exec($query);
        }
        $db->close();
    }

    /**
     * Parse/format a date/time from a string
     *
     * @param ?string $value The date/time to be parsed and formatted
     * @return string|null The date/time in `DateTimeInterface::ATOM` format, or `null` if the input cannot be parsed
     */
    public static function formatDate(?string $value): ?string {
        try {
            return $value ? (new DateTimeImmutable($value))->format(DateTimeInterface::ATOM) : null;
        } catch (Exception) {
            return null;
        }
    }

    /**
     * Return the last SQLite error message as a result array
     *
     * @param SQLite3 $db The database connection on which the error has occurred
     * @return string[] ['error' => message] for last SQLite error message
     */
    public static function error(SQLite3 $db): array {
        return ['error' => 'SQLite error: ' . $db->lastErrorMsg()];
    }
}