<?php
/**
 * Functions for the Torn Vault Tracker application.
 *
 * PHP version 8.1+
 *
 * @category Functions
 * @package  TornVaultTracker
 * @author   Keith Solomon <ksolomon@gmail.com>
 * @license  Unlicense https://unlicense.org/
 * @link     https://github.com/ksolomon/TornVaultTracker
 */

// Include settings from configuration file
require_once __DIR__ . '/config.php';

// Include utility functions
require_once 'includes/exceptions.php';
require_once 'includes/utilities.php';

/**
 * Returns a PDO connection to the database
 * This function creates the database connection and creates the database
 * file if it doesn't exist, and the vault table if it doesn't exist.
 *
 * @return PDO
 */
function getDatabaseConnection() {
    static $pdo = null;

    // SQL to create the vault table if it doesn't exist
    $createTableSQL = "CREATE TABLE IF NOT EXISTS vault (
        id TEXT PRIMARY KEY,
        user TEXT NOT NULL,
        timestamp INTEGER NOT NULL,
        description TEXT NOT NULL,
        amount REAL NOT NULL
    );";

    if ($pdo === null) {
        try {
            $pdo = new PDO(DB_DSN, DB_USER, DB_PASSWORD);
            $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

            $pdo->exec($createTableSQL);
        } catch (PDOException $e) {
            die("Database connection failed: " . $e->getMessage());
        }
    }

    return $pdo;
}

/**
 * Pulls and stores the full vault transaction log history for a user.
 *
 * Pages through the v2 Torn API using `_metadata.links.next` until the
 * API reports no further pages. Intended for first-run use when the
 * local database is empty. Idempotent: re-running on a partially
 * populated database inserts only new entries (ON CONFLICT DO NOTHING).
 *
 * @param string $user The user whose logs should be fetched.
 *
 * @return void
 */
function backfillUserLogs($user) {
    $url  = 'https://api.torn.com/v2/user?selections=log&log=5850,5851';
    $pdo  = getDatabaseConnection();

    do {
        $next = fetchAndStoreLogPage($pdo, $user, $url);
        $url  = $next;
    } while ($next !== null);
}

/**
 * Synchronizes recent vault transactions for a user.
 *
 * On a non-empty database, fetches only entries newer than the user's
 * most recent row. Falls back to full backfill when the database is
 * empty.
 *
 * @param string $user The user whose logs should be synced.
 *
 * @return void
 */
function syncUserLogs($user) {
    if (dbNew()) {
        backfillUserLogs($user);
        return;
    }

    $pdo = getDatabaseConnection();

    $stmt = $pdo->prepare('SELECT MAX(timestamp) AS max_ts FROM vault WHERE user = :user');
    $stmt->bindValue(':user', $user);
    $stmt->execute();
    $lastTs = (int)$stmt->fetch(PDO::FETCH_ASSOC)['max_ts'];

    $url = "https://api.torn.com/v2/user?selections=log&log=5850,5851&from=" . ($lastTs + 1);

    do {
        $next = fetchAndStoreLogPage($pdo, $user, $url);
        $url  = $next;
    } while ($next !== null);
}

/**
 * Generate the current balance for a user or all users
 *
 * @param string $name (optional) The user to get the balance for. If not provided, all users' balances will be added.
 *
 * @return string The balance as a formatted string
 */
function generateBalance($name=null) {
    $balance = vaultLoop($name);

    return number_format($balance, 0); // Format the balance as an integer
}

/**
 * Calculate the available vault space for a user or all users.
 *
 * This function calculates the remaining space in the vault based on the
 * transactions for a specific user or all users. If a user is specified,
 * the available space is calculated against a limit of 500,000,000.
 * If no user is specified, the available space is calculated against a
 * total vault limit of 1,000,000,000.
 *
 * @param string|null $name (optional) The user to calculate the vault space for.
 *                          If not provided, calculates for all users.
 *
 * @return string The available vault space as a formatted string.
 */
function getSpace($name=null) {
    $space = vaultLoop($name);

    if ($name === null) {
        $space = 1000000000 - $space;
    } else {
        $space = 500000000 - $space;
    }

    return number_format($space, 0); // Format the balance as an integer
}

/**
 * Builds an HTML table of all transactions in the vault
 *
 * Loops over all records in the vault and builds a table of the user, timestamp,
 * description and amount of each transaction. Amounts are formatted as integers.
 *
 * @return void
 */
function buildTable () {
    $records = fetchVaultRecords();

    foreach ($records as $entry) {
        $user        = $entry['user'];
        $timestamp   = $entry['timestamp'];
        $description = $entry['description'];
        $amount      = $entry['amount'];
        $sign        = getSign($amount);

        if ($description == 'Vault withdraw') {
            $class  = 'debit';
            $amount = substr($amount, 1); // Remove the negative sign
        } else {
            $class  = 'credit';
        }

        $amount = number_format($amount, 0); // Format the amount as an integer

        echo '<tr class="'.$class.'">';
        echo '<td>'.$user.'</td>';
        echo '<td>'.date("F j, Y / H:i", $timestamp).'</td>';
        echo '<td>'.$description.'</td>';
        echo '<td>'.$sign.$amount.'</td>';
        echo '</tr>';
    }
}