<?php

declare(strict_types=1);

namespace App;

use PDO;

final class Database
{
    public static function connect(string $path): PDO
    {
        $dir = dirname($path);
        if (!is_dir($dir) && !mkdir($dir, 0775, true) && !is_dir($dir)) {
            throw new \RuntimeException(sprintf('Unable to create database directory "%s".', $dir));
        }

        $pdo = new PDO('sqlite:' . $path, null, null, [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES => false,
        ]);

        $pdo->exec('PRAGMA journal_mode = WAL');
        $pdo->exec('PRAGMA busy_timeout = 5000');
        $pdo->exec('PRAGMA foreign_keys = ON');

        self::migrate($pdo);

        return $pdo;
    }

    private static function migrate(PDO $pdo): void
    {
        $pdo->exec(<<<'SQL'
            CREATE TABLE IF NOT EXISTS items (
                id           TEXT PRIMARY KEY,
                source       TEXT NOT NULL,
                feed_label   TEXT,
                feed_url     TEXT NOT NULL,
                title        TEXT NOT NULL,
                link         TEXT NOT NULL,
                author       TEXT,
                published_at TEXT,
                description  TEXT,
                thumbnail    TEXT,
                fetched_at   TEXT NOT NULL
            )
            SQL);

        $pdo->exec('CREATE INDEX IF NOT EXISTS idx_items_published ON items (published_at DESC)');
        $pdo->exec('CREATE INDEX IF NOT EXISTS idx_items_source ON items (source, published_at DESC)');

        $pdo->exec(<<<'SQL'
            CREATE TABLE IF NOT EXISTS feeds (
                url             TEXT PRIMARY KEY,
                source          TEXT NOT NULL,
                label           TEXT,
                last_attempt_at TEXT,
                last_success_at TEXT,
                last_error      TEXT,
                origin          TEXT NOT NULL DEFAULT 'config',
                enabled         INTEGER NOT NULL DEFAULT 1
            )
            SQL);

        // SQLite has no "ADD COLUMN IF NOT EXISTS": migrate pre-existing tables.
        self::addColumn($pdo, 'feeds', 'origin', "ALTER TABLE feeds ADD COLUMN origin TEXT NOT NULL DEFAULT 'config'");
        self::addColumn($pdo, 'feeds', 'enabled', 'ALTER TABLE feeds ADD COLUMN enabled INTEGER NOT NULL DEFAULT 1');
    }

    private static function addColumn(PDO $pdo, string $table, string $column, string $sql): void
    {
        $existing = [];
        foreach ($pdo->query(sprintf('PRAGMA table_info(%s)', $table)) as $row) {
            $existing[strtolower((string) $row['name'])] = true;
        }

        if (!isset($existing[strtolower($column)])) {
            $pdo->exec($sql);
        }
    }
}