<?php
defined('BASEPATH') or exit('No direct script access allowed');

class GCalService
{
    private $jsonPath;
    private $tokenUri = 'https://oauth2.googleapis.com/token';
    private $scopes   = 'https://www.googleapis.com/auth/calendar https://www.googleapis.com/auth/calendar.events';

    public function __construct($params = [])
    {
        $this->jsonPath = $params['jsonPath'] ?? APPPATH.'credentials/service_account.json';
        if (!file_exists($this->jsonPath)) {
            throw new Exception("Service account JSON introuvable: ".$this->jsonPath);
        }
    }

    // ----- Utils
    private function b64url($data){ return rtrim(strtr(base64_encode($data), '+/', '-_'), '='); }

    private function http($method, $url, $headers = [], $body = null)
    {
        $ch = curl_init($url);
        $opts = [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_CUSTOMREQUEST  => $method,
            CURLOPT_TIMEOUT        => 30,
            CURLOPT_HTTPHEADER     => $headers
        ];
        if ($body !== null) {
            $opts[CURLOPT_POSTFIELDS] = $body;
        }
        curl_setopt_array($ch, $opts);
        $res  = curl_exec($ch);
        $code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        if ($res === false) {
            $err = curl_error($ch);
            curl_close($ch);
            throw new Exception("cURL error: $err");
        }
        curl_close($ch);
        return [$code, $res];
    }

    private function getAccessToken($impersonateEmail)
    {
        $creds = json_decode(file_get_contents($this->jsonPath), true);
        $client_email = $creds['client_email'];
        $private_key  = $creds['private_key'];
        $now = time();

        $header = ['alg'=>'RS256','typ'=>'JWT'];
        $claim  = [
            'iss'   => $client_email,
            'scope' => $this->scopes,
            'aud'   => $this->tokenUri,
            'exp'   => $now + 3600,
            'iat'   => $now,
            'sub'   => $impersonateEmail  // Domain-Wide Delegation
        ];

        $jwt_unsigned = $this->b64url(json_encode($header)).'.'.$this->b64url(json_encode($claim));
        $signature = '';
        if (!openssl_sign($jwt_unsigned, $signature, $private_key, 'sha256WithRSAEncryption')) {
            throw new Exception("openssl_sign failed (clé privée invalide?)");
        }
        $jwt = $jwt_unsigned.'.'.$this->b64url($signature);

        list($code, $body) = $this->http(
            'POST',
            $this->tokenUri,
            ['Content-Type: application/x-www-form-urlencoded'],
            http_build_query([
                'grant_type' => 'urn:ietf:params:oauth:grant-type:jwt-bearer',
                'assertion'  => $jwt
            ])
        );
        if ($code !== 200) {
            throw new Exception("Token error ($code): ".$body);
        }
        $tok = json_decode($body, true);
        return $tok['access_token'];
    }

    // ----- Public API

    /**
     * Crée un événement et retourne ['eventId'=>..., 'calendarId'=>...]
     * $payload = [
     *   'summary','description','start','end','timezone','attendees'=>[['email'=>'...'],...]
     * ]
     */
    public function createEvent($impersonateEmail, $calendarId, array $payload)
    {
        $access = $this->getAccessToken($impersonateEmail);

        // Normalisation
        $calendarId = $calendarId ?: 'primary';
        $tz         = $payload['timezone'] ?? date_default_timezone_get();

        $event = [
            'summary'     => $payload['summary']     ?? '(Sans titre)',
            'description' => $payload['description'] ?? '',
            'start'       => isset($payload['start']) ? ['dateTime'=>$payload['start'], 'timeZone'=>$tz] : null,
            'end'         => isset($payload['end'])   ? ['dateTime'=>$payload['end'],   'timeZone'=>$tz] : null,
        ];
        if (!empty($payload['attendees'])) $event['attendees'] = $payload['attendees'];

        list($code, $body) = $this->http(
            'POST',
            "https://www.googleapis.com/calendar/v3/calendars/".rawurlencode($calendarId)."/events",
            ['Authorization: Bearer '.$access, 'Content-Type: application/json'],
            json_encode($event)
        );
        if ($code < 200 || $code >= 300) {
            throw new Exception("Create event error ($code): $body");
        }
        $resp = json_decode($body, true);
        return ['eventId'=>$resp['id'], 'calendarId'=>$calendarId];
    }

    /**
     * Met à jour un événement existant.
     */
    public function updateEvent($impersonateEmail, $calendarId, $eventId, array $payload)
    {
        $access = $this->getAccessToken($impersonateEmail);
        $calendarId = $calendarId ?: 'primary';
        $tz   = $payload['timezone'] ?? date_default_timezone_get();

        $eventPatch = [];
        foreach (['summary','description'] as $k) {
            if (array_key_exists($k, $payload)) $eventPatch[$k] = $payload[$k];
        }
        if (isset($payload['start'])) $eventPatch['start'] = ['dateTime'=>$payload['start'], 'timeZone'=>$tz];
        if (isset($payload['end']))   $eventPatch['end']   = ['dateTime'=>$payload['end'],   'timeZone'=>$tz];
        if (isset($payload['attendees'])) $eventPatch['attendees'] = $payload['attendees'];

        list($code, $body) = $this->http(
            'PATCH',
            "https://www.googleapis.com/calendar/v3/calendars/".rawurlencode($calendarId)."/events/".rawurlencode($eventId),
            ['Authorization: Bearer '.$access, 'Content-Type: application/json'],
            json_encode($eventPatch)
        );
        if ($code < 200 || $code >= 300) {
            throw new Exception("Update event error ($code): $body");
        }
        return true;
    }

    /**
     * (Optionnel) Suppression
     */
    public function deleteEvent($impersonateEmail, $calendarId, $eventId)
    {
        $access = $this->getAccessToken($impersonateEmail);
        $calendarId = $calendarId ?: 'primary';
        list($code, $body) = $this->http(
            'DELETE',
            "https://www.googleapis.com/calendar/v3/calendars/".rawurlencode($calendarId)."/events/".rawurlencode($eventId),
            ['Authorization: Bearer '.$access]
        );
        if ($code !== 204) { // 204 = No Content (OK)
            throw new Exception("Delete event error ($code): $body");
        }
        return true;
    }
// application/libraries/GCalService.php

    public function listEvents(string $userEmail, string $calendarId, string $timeMinIso, string $timeMaxIso): array
    {
        // ===== Résolution ROBUSTE du service Calendar sans getServiceFor() =====
        // 1) Si ta classe a déjà $this->service (comme tes create/update/delete), on l'utilise.
        if (isset($this->service)) {
            $service = $this->service;

            // 2) Si tu as une méthode getClient() (souvent le cas dans tes libs Google),
            //    on l'emploie pour construire le service.
        } elseif (method_exists($this, 'getClient')) {
            $client  = $this->getClient($userEmail); // si getClient n'accepte pas d'email, appelle-la sans argument
            $service = new Google_Service_Calendar($client);

            // 3) Si tu exposes un client brut ($this->client), on crée le service à partir de là.
        } elseif (isset($this->client)) {
            $service = new Google_Service_Calendar($this->client);

            // 4) Si tu as une propriété $this->calendar ou $this->calendarService déjà prête.
        } elseif (isset($this->calendar)) {
            $service = $this->calendar;
        } elseif (isset($this->calendarService)) {
            $service = $this->calendarService;

        } else {
            // Dernier recours : on tente une méthode "buildService" si elle existe,
            // sinon on lève une exception claire pour que le log te guide.
            if (method_exists($this, 'buildService')) {
                $service = $this->buildService($userEmail);
            } else {
                throw new Exception('GCalService: aucun service Calendar initialisé (ni $this->service, ni getClient(), ni $this->client).');
            }
        }
        // ======================================================================

        $opt = [
            'timeMin'      => $timeMinIso,      // RFC3339
            'timeMax'      => $timeMaxIso,      // RFC3339
            'singleEvents' => true,             // déroule les occurrences
            'orderBy'      => 'startTime',
            'maxResults'   => 2500,
        ];

        $items = [];
        do {
            $resp = $service->events->listEvents($calendarId, $opt);

            // Google renvoie des objets; on normalise pour le helper gcal_find_slot_minute()
            foreach ($resp->getItems() as $ev) {
                $start = $ev->getStart();
                $end   = $ev->getEnd();
                $items[] = [
                    'start' => [
                        'dateTime' => $start ? $start->getDateTime() : null,
                        'date'     => $start ? $start->getDate()     : null,
                    ],
                    'end' => [
                        'dateTime' => $end ? $end->getDateTime() : null,
                        'date'     => $end ? $end->getDate()     : null,
                    ],
                ];
            }

            $opt['pageToken'] = $resp->getNextPageToken();
        } while (!empty($opt['pageToken']));

        return $items;
    }

// Retourne les intervalles occupés [start,end) sous forme d'array de paires [DateTime $s, DateTime $e]
    public function freeBusy(string $userEmail, string $calendarId, string $timeMinIso, string $timeMaxIso, string $tz = 'America/Toronto'): array
    {
        // Initialisation du service identique à tes autres méthodes
        if (isset($this->service)) {
            $service = $this->service;
        } elseif (method_exists($this, 'getClient')) {
            $client  = $this->getClient(); // adapte si ta getClient prend $userEmail
            $service = new Google_Service_Calendar($client);
        } elseif (isset($this->client)) {
            $service = new Google_Service_Calendar($this->client);
        } else {
            throw new Exception('GCalService: service Calendar non initialisé pour freeBusy().');
        }

        // Requête FreeBusy
        $fbReq = new Google_Service_Calendar_FreeBusyRequest();
        $fbReq->setTimeMin($timeMinIso);
        $fbReq->setTimeMax($timeMaxIso);
        $fbReq->setTimeZone($tz);

        $item   = new Google_Service_Calendar_FreeBusyRequestItem();
        $item->setId($calendarId); // "primary" ou un ID spécifique
        $fbReq->setItems([$item]);

        $resp = $service->freebusy->query($fbReq);
        $cals = $resp->getCalendars();

        $busy = [];
        if (isset($cals[$calendarId])) {
            $blocks = $cals[$calendarId]['busy'] ?? [];
            foreach ($blocks as $b) {
                // $b['start'] et $b['end'] sont des RFC3339
                $s = new DateTime($b['start']);
                $e = new DateTime($b['end']);
                // On ne change pas le fuseau ici: Google renvoie des instants absolus.
                $busy[] = [$s, $e];
            }
        }

        return $busy;
    }

}