<?php

declare(strict_types=1);

namespace App\Http\Controllers;

use App\Models\User;
use App\Services\SamlIdpService;
use Illuminate\Http\{Request, Response};
use Illuminate\Support\Facades\{Auth, Log};
use Throwable;

class SamlIdpController extends Controller
{
    public function __construct(private readonly SamlIdpService $samlService) {}

    /**
     * SAML 2.0 Single Sign-On (SSO) Endpoint.
     * Handles both GET (Redirect binding) and POST (POST binding) requests.
     */
    public function sso(Request $request)
    {
        $samlRequest = $request->input('SAMLRequest') ?? session('saml_pending_request');
        $relayState = $request->input('RelayState') ?? session('saml_pending_relay_state');

        Log::info('SAML SSO Request received.', [
            'ip' => $request->ip(),
            'method' => $request->method(),
            'has_saml_request' => ! empty($samlRequest),
            'has_relay_state' => ! empty($relayState),
            'session_has_pending' => session()->has('saml_pending_request'),
        ]);

        if (empty($samlRequest)) {
            Log::warning('SAML SSO access rejected: Missing SAMLRequest parameter.', [
                'ip' => $request->ip(),
            ]);
            abort(400, 'Missing SAMLRequest parameter.');
        }

        try {
            Log::info('Decoding and parsing SAMLRequest XML payload.');
            $parsed = $this->samlService->parseRequest($samlRequest);
            Log::info('SAMLRequest successfully parsed.', [
                'request_id' => $parsed['requestId'],
                'issuer' => $parsed['issuer'],
                'acs_url' => $parsed['acsUrl'],
            ]);
        } catch (Throwable $e) {
            Log::error('SAMLRequest parsing failed.', [
                'ip' => $request->ip(),
                'error' => $e->getMessage(),
            ]);
            abort(400, 'Invalid SAMLRequest: '.$e->getMessage());
        }

        // Find corresponding Connected App by issuer (SAML Entity ID)
        $connectedApp = $this->samlService->findConnectedApp($parsed['issuer']);

        if (! $connectedApp) {
            Log::warning('SAML SSO access rejected: Unregistered Service Provider (EntityID / Issuer).', [
                'issuer' => $parsed['issuer'],
                'request_id' => $parsed['requestId'],
                'ip' => $request->ip(),
            ]);
            abort(
                403,
                "The Service Provider [{$parsed['issuer']}] is not authorized in this system.",
            );
        }

        Log::info('SAML ConnectedApp matched successfully.', [
            'app_id' => $connectedApp->id,
            'app_name' => $connectedApp->name,
            'status' => $connectedApp->status?->name,
        ]);

        if ('disconnected' === $connectedApp->status?->name) {
            Log::warning('SAML SSO access rejected: Connected App is deactivated.', [
                'app_id' => $connectedApp->id,
                'app_name' => $connectedApp->name,
                'request_id' => $parsed['requestId'],
            ]);
            abort(
                403,
                "The Service Provider [{$connectedApp->name}] is currently deactivated.",
            );
        }

        /**
         * @var array{
         * saml?: array{
         * entity_id?: string,
         * acs_url?: string
         * }
         * } $settings
         */
        $settings = $connectedApp->settings;
        $acsUrl = $parsed['acsUrl'] ?: $settings['saml']['acs_url'] ?? null;

        if (empty($acsUrl)) {
            Log::error('SAML SSO failed: Assertion Consumer Service (ACS) URL is undefined.', [
                'app_id' => $connectedApp->id,
                'app_name' => $connectedApp->name,
                'request_id' => $parsed['requestId'],
            ]);
            abort(400, 'Assertion Consumer Service (ACS) URL is not defined.');
        }

        // Authenticate the User
        if (! Auth::check()) {
            Log::info('SAML SSO guest session intercepted. Persisting request parameters to session and redirecting to login.', [
                'request_id' => $parsed['requestId'],
                'relay_state' => $relayState,
                'ip' => $request->ip(),
            ]);

            session([
                'saml_pending_request' => $samlRequest,
                'saml_pending_relay_state' => $relayState,
            ]);

            return redirect()->route('login');
        }

        /** @var User $user */
        $user = Auth::user();

        Log::info('SAML SSO user authenticated session detected. Generating signed SAML Response assertion.', [
            'user_id' => $user->id,
            'user_email' => $user->email,
            'app_id' => $connectedApp->id,
            'app_name' => $connectedApp->name,
            'acs_url' => $acsUrl,
            'request_id' => $parsed['requestId'],
        ]);

        try {
            $samlResponse = $this->samlService->generateResponse(
                $user,
                $connectedApp,
                $parsed['requestId'],
                $acsUrl,
            );
            Log::info('Signed SAML Response assertion successfully generated.');
        } catch (Throwable $e) {
            Log::error('SAML Response generation failed.', [
                'user_id' => $user->id,
                'app_id' => $connectedApp->id,
                'error' => $e->getMessage(),
            ]);
            abort(500, 'Cryptographic signing of SAML Response failed.');
        }

        // Clear pending SAML request from session
        session()->forget(['saml_pending_request', 'saml_pending_relay_state']);
        Log::info('Pending SAML session parameters cleared.');

        Log::info('Rendering SAML HTTP-POST auto-submission redirect form.', [
            'user_id' => $user->id,
            'app_name' => $connectedApp->name,
            'acs_url' => $acsUrl,
            'relay_state' => $relayState,
        ]);

        // Return HTTP-POST Auto-Submission Page
        return view('saml.post_response', [
            'appName' => $connectedApp->name,
            'acsUrl' => $acsUrl,
            'samlResponse' => $samlResponse,
            'relayState' => $relayState,
        ]);
    }

    /**
     * SAML 2.0 Identity Provider (IdP) Metadata Endpoint.
     * Exposes public keys and bindings to Service Providers like Microsoft Entra ID.
     */
    public function metadata(): Response
    {
        $idpEntityId = route('saml.metadata');
        $ssoUrl = route('saml.sso');

        Log::info('SAML IdP Metadata requested.', [
            'ip' => request()->ip(),
            'user_agent' => request()->userAgent(),
            'entity_id' => $idpEntityId,
            'sso_url' => $ssoUrl,
        ]);

        try {
            $metadataXml = $this->samlService->generateMetadata(
                $idpEntityId,
                $ssoUrl,
            );
            Log::info('SAML IdP Metadata XML descriptor generated successfully.');
        } catch (Throwable $e) {
            Log::error('SAML IdP Metadata XML generation failed.', [
                'error' => $e->getMessage(),
            ]);
            abort(
                500,
                'Failed to retrieve Identity Provider cryptographic identity.',
            );
        }

        return response($metadataXml, 200, [
            'Content-Type' => 'application/xml; charset=utf-8',
        ]);
    }
}