<?php

namespace App\Services\PBX;

use App\Exceptions\PBX\PBXConnectionException;
use App\Exceptions\PBX\PBXException;
use App\Models\PBXApiCredential;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

/**
 * FreePBX API Client
 *
 * Authenticates via OAuth 2.0 client_credentials grant and supports both
 * the GraphQL API (/admin/api/api/gql) and the REST API (/admin/api/api/rest/{module}/{route}).
 *
 * URL routing in FreePBX (via .htaccess rewrite):
 *   /admin/api/api/{module}/{command}/{route}
 *   → /admin/api/api.php?module={module}&command={command}&route={route}
 *
 * Token endpoint: POST /admin/api/api/token
 * GraphQL:        POST /admin/api/api/gql
 * REST:           ANY  /admin/api/api/rest/{freepbx_module}/{route}
 */
class PBXApiClient
{
    protected string $baseUrl;
    protected string $clientId;
    protected string $clientSecret;
    protected int $timeout = 30;

    /** Cached Bearer tokens keyed by scope string */
    protected array $tokenCache = [];

    public function __construct(?PBXApiCredential $credential = null)
    {
        // Guard against an empty model the IoC container may inject for the nullable type hint.
        // An Eloquent model that has never been saved has exists = false and all attributes null.
        if (!$credential || !$credential->exists) {
            $credentialManager = new PBXCredentialManager();
            $credential = $credentialManager->ensurePrimaryCredential();
        }

        if (!$credential || !$credential->isValid()) {
            throw new PBXConnectionException('No valid PBX API credentials available');
        }

        $this->baseUrl      = rtrim($credential->api_url, '/');
        $this->clientId     = $credential->api_user;
        $this->clientSecret = $credential->getDecryptedSecret();

        $credential->markAsUsed();
    }

    // -------------------------------------------------------------------------
    // OAuth 2.0 Token Management
    // -------------------------------------------------------------------------

    /**
     * Obtain an OAuth 2.0 Bearer token using the client_credentials grant.
     * Tokens are cached in-memory for the lifetime of this object.
     *
     * @param string $scope  FreePBX scope key: 'rest', 'gql', or 'rest gql'
     * @return string
     * @throws PBXConnectionException
     */
    public function getToken(string $scope = 'rest gql'): string
    {
        $cacheKey = md5($scope);

        if (
            isset($this->tokenCache[$cacheKey]) &&
            $this->tokenCache[$cacheKey]['expires_at'] > time() + 60
        ) {
            return $this->tokenCache[$cacheKey]['token'];
        }

        $tokenUrl = $this->baseUrl . '/admin/api/api/token';

        try {
            $response = Http::timeout($this->timeout)
                ->asForm()
                ->post($tokenUrl, [
                    'grant_type'    => 'client_credentials',
                    'client_id'     => $this->clientId,
                    'client_secret' => $this->clientSecret,
                    'scope'         => $scope,
                ]);

            if (!$response->successful()) {
                throw new PBXConnectionException(
                    'FreePBX token request failed (' . $response->status() . '): ' . $response->body()
                );
            }

            $data = $response->json();

            if (empty($data['access_token'])) {
                throw new PBXConnectionException(
                    'FreePBX token response missing access_token: ' . $response->body()
                );
            }

            $this->tokenCache[$cacheKey] = [
                'token'      => $data['access_token'],
                'expires_at' => time() + ($data['expires_in'] ?? 3600),
            ];

            Log::debug('PBX OAuth token acquired', ['scope' => $scope]);

            return $this->tokenCache[$cacheKey]['token'];

        } catch (PBXConnectionException $e) {
            throw $e;
        } catch (\Exception $e) {
            throw new PBXConnectionException(
                'Failed to obtain FreePBX OAuth token: ' . $e->getMessage(),
                0,
                $e
            );
        }
    }

    // -------------------------------------------------------------------------
    // GraphQL API  (/admin/api/api/gql)
    // -------------------------------------------------------------------------

    /**
     * Execute a GraphQL query or mutation against the FreePBX API.
     *
     * @param string $query      GraphQL query/mutation string
     * @param array  $variables  GraphQL variables
     * @return array             Decoded JSON response
     * @throws PBXException
     */
    public function graphql(string $query, array $variables = []): array
    {
        $token = $this->getToken('gql');
        $url   = $this->baseUrl . '/admin/api/api/gql';

        try {
            $response = Http::timeout($this->timeout)
                ->withToken($token)
                ->post($url, array_filter([
                    'query'     => $query,
                    'variables' => $variables ?: null,
                ]));

            if (!$response->successful()) {
                $this->handleErrorResponse($response, 'POST', 'gql');
            }

            $data = $response->json() ?? [];

            if (!empty($data['errors'])) {
                $messages = implode('; ', array_column($data['errors'], 'message'));
                Log::error('FreePBX GraphQL errors', [
                    'query'  => substr($query, 0, 200),
                    'errors' => $data['errors'],
                ]);
                throw new PBXException('FreePBX GraphQL error: ' . $messages);
            }

            return $data['data'] ?? [];

        } catch (PBXException $e) {
            throw $e;
        } catch (\Illuminate\Http\Client\ConnectionException $e) {
            throw new PBXConnectionException(
                'Failed to connect to FreePBX GraphQL API: ' . $e->getMessage(), 0, $e
            );
        } catch (\Exception $e) {
            throw new PBXException(
                'FreePBX GraphQL request failed: ' . $e->getMessage(), 0, $e
            );
        }
    }

    // -------------------------------------------------------------------------
    // REST API  (/admin/api/api/rest/{freepbxModule}/{route})
    // -------------------------------------------------------------------------

    /**
     * Make a GET request to a FreePBX REST module endpoint.
     *
     * @param string $module  FreePBX module name (e.g. 'core', 'userman', 'framework')
     * @param string $route   Route within the module (e.g. 'users', 'users/1000')
     * @param array  $query   Query-string parameters
     * @return array
     * @throws PBXException
     */
    public function get(string $module, string $route = '', array $query = []): array
    {
        return $this->restRequest('GET', $module, $route, [], $query);
    }

    /**
     * Make a POST request to a FreePBX REST module endpoint.
     */
    public function post(string $module, string $route, array $data = []): array
    {
        return $this->restRequest('POST', $module, $route, $data);
    }

    /**
     * Make a PUT request to a FreePBX REST module endpoint.
     */
    public function put(string $module, string $route, array $data = []): array
    {
        return $this->restRequest('PUT', $module, $route, $data);
    }

    /**
     * Make a DELETE request to a FreePBX REST module endpoint.
     */
    public function delete(string $module, string $route): array
    {
        return $this->restRequest('DELETE', $module, $route);
    }

    protected function restRequest(
        string $method,
        string $module,
        string $route = '',
        array  $data  = [],
        array  $query = []
    ): array {
        $token = $this->getToken('rest');
        $path  = '/admin/api/api/rest/' . trim($module, '/') . ('' !== $route ? '/' . ltrim($route, '/') : '');
        $url   = $this->baseUrl . $path;

        try {
            $response = Http::timeout($this->timeout)
                ->withToken($token)
                ->send($method, $url, [
                    'json'  => $data  ?: null,
                    'query' => $query ?: null,
                ]);

            if (!$response->successful()) {
                $this->handleErrorResponse($response, $method, $path);
            }

            return $response->json() ?? [];

        } catch (PBXException $e) {
            throw $e;
        } catch (\Illuminate\Http\Client\ConnectionException $e) {
            throw new PBXConnectionException(
                'Failed to connect to FreePBX REST API: ' . $e->getMessage(), 0, $e,
                ['path' => $path]
            );
        } catch (\Exception $e) {
            throw new PBXException(
                'FreePBX REST request failed: ' . $e->getMessage(), 0, $e,
                ['path' => $path]
            );
        }
    }

    protected function handleErrorResponse($response, string $method, string $endpoint): void
    {
        $status  = $response->status();
        $body    = $response->json() ?? [];
        $message = $body['message'] ?? $body['error'] ?? $response->body();

        Log::error('PBX API error response', [
            'method'   => $method,
            'endpoint' => $endpoint,
            'status'   => $status,
            'body'     => $body,
        ]);

        throw new PBXException(
            "PBX API Error ({$status}): {$message}",
            $status,
            null,
            ['method' => $method, 'endpoint' => $endpoint, 'response' => $body]
        );
    }

    // -------------------------------------------------------------------------
    // Convenience helpers
    // -------------------------------------------------------------------------

    /**
     * Test connectivity by calling the lightweight /framework/version REST endpoint.
     */
    public function testConnection(): bool
    {
        try {
            $this->get('framework', 'version');
            return true;
        } catch (\Exception $e) {
            Log::warning('PBX API connection test failed', ['error' => $e->getMessage()]);
            return false;
        }
    }

    /**
     * Trigger a FreePBX "Apply Config" / dialplan reload via GraphQL.
     *
     * The doreload mutation requires an input argument (even though the input type is empty).
     * See: FreePBX API test ModuleAdminGqlApiTest.php:394 — doreload(input: { })
     */
    public function applyChanges(): bool
    {
        try {
            $this->graphql(
                'mutation DoReload($input: doreloadInput!) { doreload(input: $input) { status message } }',
                ['input' => new \stdClass()]
            );
            return true;
        } catch (\Exception $e) {
            Log::error('Failed to apply PBX configuration changes', ['error' => $e->getMessage()]);
            throw new PBXException('Failed to apply configuration changes: ' . $e->getMessage(), 0, $e);
        }
    }
}