<?php
declare(strict_types=1);
session_start();
require_once 'db/config.php';

if (!isset($_SESSION['user_id'])) {
    header("Location: /login.php");
    exit;
}

$application_id = isset($_GET['id']) ? (int)$_GET['id'] : 0;
$user_id = $_SESSION['user_id'];

if (!$application_id) {
    header("Location: /index.php");
    exit;
}

$pdo = db();

// Begin a transaction
$pdo->beginTransaction();

try {
    // Get application and task details, and ensure the current user owns the task
    $stmt = $pdo->prepare(
        "SELECT a.id as application_id, a.task_id, t.user_id as task_owner_id
         FROM applications a
         JOIN tasks t ON a.task_id = t.id
         WHERE a.id = ? AND t.user_id = ?"
    );
    $stmt->execute([$application_id, $user_id]);
    $application_info = $stmt->fetch(PDO::FETCH_ASSOC);

    if (!$application_info) {
        // If no result, either application doesn't exist or user doesn't own the task.
        throw new Exception("Authorization failed or application not found.");
    }

    $task_id = $application_info['task_id'];

    // 1. Update the accepted application's status to 'accepted'
    $stmt = $pdo->prepare("UPDATE applications SET status = 'accepted' WHERE id = ?");
    $stmt->execute([$application_id]);

    // 2. Update the task's status to 'assigned'
    $stmt = $pdo->prepare("UPDATE tasks SET status = 'assigned' WHERE id = ?");
    $stmt->execute([$task_id]);

    // 3. Reject all other pending applications for this task
    $stmt = $pdo->prepare("UPDATE applications SET status = 'rejected' WHERE task_id = ? AND id != ? AND status = 'pending'");
    $stmt->execute([$task_id, $application_id]);

    // If all queries were successful, commit the transaction
    $pdo->commit();

    header("Location: /task-details.php?id=" . $task_id . "&message=application_accepted");
    exit;

} catch (Exception $e) {
    // If any query fails, roll back the transaction
    $pdo->rollBack();
    error_log($e->getMessage());
    // Redirect with a generic error. Avoid exposing specific DB errors.
    header("Location: /task-details.php?id=" . ($task_id ?? 0) . "&message=acceptance_failed");
    exit;
}