<?php
/**
 * Pantry Inventory API
 *
 * Simple JSON file-based backend for the pantry inventory app.
 * No database required - stores everything in inventory.json
 */

header('Content-Type: application/json');

// CORS - restrict to same origin (remove for local development if needed)
$allowedOrigins = [
    'https://pantry.kestrelsnest.social',
    'http://localhost:8000'
];
$origin = $_SERVER['HTTP_ORIGIN'] ?? '';
if (in_array($origin, $allowedOrigins)) {
    header("Access-Control-Allow-Origin: $origin");
}
header('Access-Control-Allow-Methods: POST, GET, OPTIONS');
header('Access-Control-Allow-Headers: Content-Type');

// Handle preflight requests
if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(200);
    exit();
}

// File paths
define('DATA_FILE', __DIR__ . '/data/inventory.json');
define('PIN_FILE', __DIR__ . '/data/pin.txt');
define('DATA_DIR', __DIR__ . '/data');

// Ensure data directory exists
if (!is_dir(DATA_DIR)) {
    mkdir(DATA_DIR, 0755, true);
}

// Default inventory (sample data using new container types)
$defaultInventory = [
    ['id' => 1, 'name' => 'Bulgur', 'container' => 'glass-flip-med-tall', 'outOfStock' => false],
    ['id' => 2, 'name' => 'Wild Rice Flour', 'container' => 'glass-flip-med-squat', 'outOfStock' => false],
    ['id' => 3, 'name' => 'Self Rising Flour', 'container' => 'plastic-oxo-large', 'outOfStock' => false],
    ['id' => 4, 'name' => 'Whole Wheat Flour', 'container' => 'plastic-oxo-large', 'outOfStock' => false],
    ['id' => 5, 'name' => 'Cake Flour', 'container' => 'plastic-clamp-large', 'outOfStock' => false],
    ['id' => 6, 'name' => 'GF Pancake Mix', 'container' => 'original-package', 'outOfStock' => false],
    ['id' => 7, 'name' => 'Coconut Flour', 'container' => 'glass-flip-small', 'outOfStock' => false],
    ['id' => 8, 'name' => 'All Purpose Flour', 'container' => 'plastic-oxo-large', 'outOfStock' => false],
    ['id' => 9, 'name' => 'Bread Flour', 'container' => 'plastic-clamp-tall', 'outOfStock' => false],
    ['id' => 10, 'name' => 'Powdered Sugar', 'container' => 'plastic-flip', 'outOfStock' => false],
    ['id' => 11, 'name' => 'Linguine', 'container' => 'original-package', 'outOfStock' => false],
    ['id' => 12, 'name' => 'Fettuccine', 'container' => 'original-package', 'outOfStock' => false],
    ['id' => 13, 'name' => 'Penne Rigate', 'container' => 'original-package', 'outOfStock' => false],
    ['id' => 14, 'name' => 'Ancho Chile', 'container' => 'glass-flip-large', 'outOfStock' => false],
    ['id' => 15, 'name' => 'Chocolate Chips', 'container' => 'glass-canning-quart', 'outOfStock' => false],
    ['id' => 16, 'name' => 'Dried Mushrooms', 'container' => 'glass-canning-pint', 'outOfStock' => false],
    ['id' => 17, 'name' => 'Bay Leaves', 'container' => 'spice-hex-large', 'outOfStock' => false],
    ['id' => 18, 'name' => 'Dates', 'container' => 'glass-canning-quart', 'outOfStock' => false],
    ['id' => 19, 'name' => 'Xanthan Gum', 'container' => 'spice-flip-tiny', 'outOfStock' => false],
    ['id' => 20, 'name' => 'M.S.G.', 'container' => 'spice-hex-small', 'outOfStock' => false],
    ['id' => 21, 'name' => 'Potato Starch', 'container' => 'glass-flip-small', 'outOfStock' => false],
    ['id' => 22, 'name' => 'Potato Flour', 'container' => 'glass-flip-small', 'outOfStock' => false],
    ['id' => 23, 'name' => 'Garbanzo Flour', 'container' => 'glass-flip-med-squat', 'outOfStock' => false],
    ['id' => 24, 'name' => 'Mochi Rice Flour', 'container' => 'glass-flip-small', 'outOfStock' => false],
    ['id' => 25, 'name' => 'Couscous', 'container' => 'original-package', 'outOfStock' => false],
    ['id' => 26, 'name' => 'Granola', 'container' => 'original-package', 'outOfStock' => false],
    ['id' => 27, 'name' => 'Cheerios', 'container' => 'original-package', 'outOfStock' => false],
    ['id' => 28, 'name' => 'Baking Powder', 'container' => 'spice-hex-large', 'outOfStock' => false],
    ['id' => 29, 'name' => 'Corn Starch', 'container' => 'glass-canning-small', 'outOfStock' => false],
    ['id' => 30, 'name' => 'Cocoa Powder', 'container' => 'spice-hex-large', 'outOfStock' => false],
];

/**
 * Load inventory from file
 */
function loadInventory() {
    global $defaultInventory;
    
    if (file_exists(DATA_FILE)) {
        $content = file_get_contents(DATA_FILE);
        $data = json_decode($content, true);
        if ($data !== null) {
            return $data;
        }
    }
    
    // Initialize with default inventory
    saveInventory($defaultInventory);
    return $defaultInventory;
}

/**
 * Save inventory to file
 */
function saveInventory($inventory) {
    file_put_contents(DATA_FILE, json_encode($inventory, JSON_PRETTY_PRINT));
}

/**
 * Check if PIN is set
 */
function hasPinSet() {
    return file_exists(PIN_FILE) && strlen(trim(file_get_contents(PIN_FILE))) === 4;
}

/**
 * Get stored PIN
 */
function getPin() {
    if (file_exists(PIN_FILE)) {
        return trim(file_get_contents(PIN_FILE));
    }
    return null;
}

/**
 * Set PIN
 */
function setPin($pin) {
    file_put_contents(PIN_FILE, $pin);
    // Secure the file
    chmod(PIN_FILE, 0600);
}

/**
 * Verify PIN
 */
function verifyPin($pin) {
    $storedPin = getPin();
    return $storedPin !== null && $storedPin === $pin;
}

/**
 * Get next available ID
 */
function getNextId($inventory) {
    if (empty($inventory)) {
        return 1;
    }
    $maxId = max(array_column($inventory, 'id'));
    return $maxId + 1;
}

/**
 * Sanitize string input
 */
function sanitize($str, $maxLength = 200) {
    $str = trim($str);
    if (strlen($str) > $maxLength) {
        $str = substr($str, 0, $maxLength);
    }
    return $str;
}

/**
 * Check if PIN is required and valid for write operations
 */
function requirePin($input) {
    // If no PIN is set yet, allow writes (first-time setup)
    if (!hasPinSet()) {
        return true;
    }

    // PIN is set, so require it for write operations
    $pin = $input['pin'] ?? '';
    return verifyPin($pin);
}

// Main request handling
$input = json_decode(file_get_contents('php://input'), true);

if (!$input || !isset($input['action'])) {
    // Allow GET requests to view inventory
    if ($_SERVER['REQUEST_METHOD'] === 'GET') {
        $inventory = loadInventory();
        echo json_encode([
            'success' => true,
            'inventory' => $inventory,
            'hasPin' => hasPinSet()
        ]);
        exit();
    }
    
    echo json_encode(['error' => 'Invalid request']);
    exit();
}

$action = $input['action'];

switch ($action) {
    case 'get':
        $inventory = loadInventory();
        echo json_encode([
            'success' => true,
            'inventory' => $inventory,
            'hasPin' => hasPinSet()
        ]);
        break;
        
    case 'setPin':
        $pin = $input['pin'] ?? '';
        
        if (strlen($pin) !== 4 || !ctype_digit($pin)) {
            echo json_encode(['success' => false, 'error' => 'PIN must be 4 digits']);
            break;
        }
        
        // Only allow setting PIN if not already set
        if (hasPinSet()) {
            echo json_encode(['success' => false, 'error' => 'PIN already set']);
            break;
        }
        
        setPin($pin);
        echo json_encode(['success' => true]);
        break;
        
    case 'verifyPin':
        $pin = $input['pin'] ?? '';
        $valid = verifyPin($pin);
        echo json_encode(['success' => $valid]);
        break;
        
    case 'add':
        if (!requirePin($input)) {
            echo json_encode(['success' => false, 'error' => 'Invalid PIN']);
            break;
        }

        $name = sanitize($input['name'] ?? '');
        $container = sanitize($input['container'] ?? 'glass-bail-medium', 50);
        $category = sanitize($input['category'] ?? 'other', 50);
        $outOfStock = (bool)($input['outOfStock'] ?? false);

        if (empty($name)) {
            echo json_encode(['success' => false, 'error' => 'Name required']);
            break;
        }

        $inventory = loadInventory();
        $newItem = [
            'id' => getNextId($inventory),
            'name' => $name,
            'container' => $container,
            'category' => $category,
            'outOfStock' => $outOfStock
        ];

        $inventory[] = $newItem;
        saveInventory($inventory);

        echo json_encode(['success' => true, 'item' => $newItem]);
        break;
        
    case 'update':
        if (!requirePin($input)) {
            echo json_encode(['success' => false, 'error' => 'Invalid PIN']);
            break;
        }

        $id = (int)($input['id'] ?? 0);
        $name = sanitize($input['name'] ?? '');
        $container = sanitize($input['container'] ?? '', 50);
        $category = sanitize($input['category'] ?? '', 50);
        $outOfStock = (bool)($input['outOfStock'] ?? false);

        if ($id <= 0) {
            echo json_encode(['success' => false, 'error' => 'Invalid ID']);
            break;
        }

        $inventory = loadInventory();
        $found = false;

        foreach ($inventory as &$item) {
            if ($item['id'] === $id) {
                if (!empty($name)) $item['name'] = $name;
                if (!empty($container)) $item['container'] = $container;
                if (!empty($category)) $item['category'] = $category;
                $item['outOfStock'] = $outOfStock;
                $found = true;
                break;
            }
        }

        if (!$found) {
            echo json_encode(['success' => false, 'error' => 'Item not found']);
            break;
        }

        saveInventory($inventory);
        echo json_encode(['success' => true]);
        break;
        
    case 'delete':
        if (!requirePin($input)) {
            echo json_encode(['success' => false, 'error' => 'Invalid PIN']);
            break;
        }

        $id = (int)($input['id'] ?? 0);

        if ($id <= 0) {
            echo json_encode(['success' => false, 'error' => 'Invalid ID']);
            break;
        }
        
        $inventory = loadInventory();
        $originalCount = count($inventory);
        $inventory = array_values(array_filter($inventory, fn($item) => $item['id'] !== $id));
        
        if (count($inventory) === $originalCount) {
            echo json_encode(['success' => false, 'error' => 'Item not found']);
            break;
        }
        
        saveInventory($inventory);
        echo json_encode(['success' => true]);
        break;
        
    default:
        echo json_encode(['error' => 'Unknown action']);
}