<?php

declare(strict_types=1);

$root = dirname(__DIR__);
require $root.'/app/LargeQuant/Support/CanonicalJson.php';

use App\LargeQuant\Support\CanonicalJson;

if ($argc < 2) {
    fwrite(STDERR, "Usage: php scripts/lqep-verify-bundle.php <evidence-bundle.json> [trusted-public-key-base64]\n");
    exit(2);
}

if (! function_exists('sodium_crypto_sign_verify_detached')) {
    fwrite(STDERR, "FAIL  ext-sodium is required.\n");
    exit(2);
}

$file = $argv[1];
if (! is_file($file)) {
    fwrite(STDERR, "FAIL  Bundle not found: {$file}\n");
    exit(2);
}

try {
    $bundle = json_decode(file_get_contents($file), true, flags: JSON_THROW_ON_ERROR);
} catch (Throwable $e) {
    fwrite(STDERR, 'FAIL  Invalid JSON: '.$e->getMessage()."\n");
    exit(2);
}

$document = $bundle['evidence_packet'] ?? null;
$payload = is_array($document) ? ($document['signed_payload'] ?? null) : null;
$signature = is_array($document) ? ($document['signature'] ?? null) : null;
$metadata = $bundle['packet_metadata'] ?? [];
$artifacts = $bundle['artifacts'] ?? [];

$results = [];
$check = function (string $label, bool $ok) use (&$results): void {
    $results[$label] = $ok;
    echo str_pad($ok ? 'PASS' : 'FAIL', 6).$label.PHP_EOL;
};

if (! is_array($payload) || ! is_array($signature)) {
    $check('Packet structure', false);
    exit(1);
}
$check('Packet structure', true);

$canonicalPayload = CanonicalJson::encode($payload);
$payloadHash = hash('sha256', $canonicalPayload);
$check('Payload SHA-256', hash_equals((string) ($metadata['payload_hash'] ?? ''), $payloadHash));

$public = base64_decode((string) ($signature['public_key_base64'] ?? ''), true);
$sig = base64_decode((string) ($signature['value_base64'] ?? ''), true);
$signatureValid = false;
if ($public !== false && $sig !== false) {
    try {
        $signatureValid = sodium_crypto_sign_verify_detached($sig, $canonicalPayload, $public);
    } catch (SodiumException) {
        $signatureValid = false;
    }
}
$check('Ed25519 signature', $signatureValid);

$identity = $payload['signing_identity'] ?? [];
$keyFingerprintValid = $public !== false
    && (($identity['algorithm'] ?? null) === 'Ed25519')
    && (($identity['key_id'] ?? null) === ($signature['key_id'] ?? null))
    && hash_equals((string) ($identity['public_key_sha256'] ?? ''), hash('sha256', $public));
$check('Signing identity fingerprint', $keyFingerprintValid);

$artifactMap = [
    'input' => 'input_sha256',
    'parameters' => 'parameters_sha256',
    'output' => 'output_sha256',
];
$artifactSetValid = count(array_intersect(array_keys($artifactMap), array_keys($artifacts))) === 3;
$check('Artifact set', $artifactSetValid);

$artifactHashesValid = true;
foreach ($artifactMap as $type => $signedKey) {
    if (! isset($artifacts[$type])) {
        $artifactHashesValid = false;
        continue;
    }

    $contentJson = $artifacts[$type]['content_json'] ?? null;
    if (! is_string($contentJson)) {
        $artifactHashesValid = false;
        continue;
    }
    try {
        json_decode($contentJson, flags: JSON_THROW_ON_ERROR);
    } catch (Throwable) {
        $artifactHashesValid = false;
        continue;
    }
    $actual = hash('sha256', $contentJson);
    $declared = (string) ($artifacts[$type]['sha256'] ?? '');
    $signedHash = (string) (($payload['artifacts'][$signedKey] ?? ''));
    $valid = hash_equals($declared, $actual) && hash_equals($signedHash, $actual);
    $artifactHashesValid = $artifactHashesValid && $valid;
}
$check('Artifact hashes & signed binding', $artifactHashesValid);

$trustedValid = true;
if (isset($argv[2]) && trim($argv[2]) !== '') {
    $trusted = base64_decode(trim($argv[2]), true);
    $trustedValid = $trusted !== false && $public !== false && hash_equals($trusted, $public);
    $check('Externally trusted public key', $trustedValid);
}

$verified = ! in_array(false, $results, true) && $trustedValid;
echo PHP_EOL;
if (! $verified) {
    fwrite(STDERR, "LQEP portable verification FAILED.\n");
    exit(1);
}

echo "LQEP portable verification PASSED.\n";