<?php
require_once 'db/config.php';

if ($_SERVER['REQUEST_METHOD'] !== 'POST' || !isset($_POST['listing_id']) || !isset($_POST['volunteer_id'])) {
    header('Location: volunteer_hub.php');
    exit();
}

$listing_id = filter_input(INPUT_POST, 'listing_id', FILTER_VALIDATE_INT);
$volunteer_id = filter_input(INPUT_POST, 'volunteer_id', FILTER_VALIDATE_INT);

if ($listing_id === false || $volunteer_id === false) {
    header('Location: volunteer_hub.php?status=error');
    exit();
}

try {
    $pdo = db();
    $pdo->beginTransaction();

    // 1. Check if the listing is still 'claimed'
    $checkSql = "SELECT status FROM food_listings WHERE id = :listing_id FOR UPDATE"; // Lock the row
    $checkStmt = $pdo->prepare($checkSql);
    $checkStmt->bindParam(':listing_id', $listing_id, PDO::PARAM_INT);
    $checkStmt->execute();
    $currentStatus = $checkStmt->fetchColumn();

    if ($currentStatus === 'claimed') {
        // 2. Update the listing status to 'assigned'
        $updateSql = "UPDATE food_listings SET status = 'assigned' WHERE id = :listing_id";
        $updateStmt = $pdo->prepare($updateSql);
        $updateStmt->bindParam(':listing_id', $listing_id, PDO::PARAM_INT);
        $updateStmt->execute();

        // 3. Create the assignment record
        $assignSql = "INSERT INTO volunteer_assignments (listing_id, volunteer_id) VALUES (:listing_id, :volunteer_id)";
        $assignStmt = $pdo->prepare($assignSql);
        $assignStmt->bindParam(':listing_id', $listing_id, PDO::PARAM_INT);
        $assignStmt->bindParam(':volunteer_id', $volunteer_id, PDO::PARAM_INT);
        $assignStmt->execute();
        
        $pdo->commit();
        header('Location: volunteer_hub.php?status=assigned');

    } else {
        // The listing was already assigned or is in another state
        $pdo->rollBack();
        header('Location: volunteer_hub.php?status=already_assigned');
    }

} catch (PDOException $e) {
    if ($pdo->inTransaction()) {
        $pdo->rollBack();
    }
    // error_log($e->getMessage());
    header('Location: volunteer_hub.php?status=error');
}

exit();