<?php
class WhatsAppService
{
    public static function sendToContact(int $contactId, string $message = '', ?int $templateId = null): array
    {
        try {
            $db = db();

            // Buscar contato
            $stmt = $db->prepare("SELECT * FROM contacts WHERE id = :id LIMIT 1");
            $stmt->execute(['id' => $contactId]);
            $contact = $stmt->fetch();

            if (!$contact) {
                return ['success' => false, 'message' => 'Contato não encontrado'];
            }

            if (empty($contact['phone'])) {
                return ['success' => false, 'message' => 'Contato sem telefone'];
            }

            $phone = preg_replace('/[^0-9]/', '', $contact['phone']);

            $settings = self::getSettings();

            // =========================
            // ENVIO DE TEMPLATE
            // =========================
            if ($templateId) {
                $tpl = $db->prepare("SELECT * FROM whatsapp_templates WHERE id = :id LIMIT 1");
                $tpl->execute(['id' => $templateId]);
                $template = $tpl->fetch();

                if (!$template) {
                    return ['success' => false, 'message' => 'Template não encontrado'];
                }

                $payload = [
                    'messaging_product' => 'whatsapp',
                    'to' => $phone,
                    'type' => 'template',
                    'template' => [
                        'name' => $template['template_key'],
                        'language' => [
                            'code' => $template['language'] ?? 'pt_BR'
                        ]
                    ]
                ];

                $response = self::sendPayload($settings, $payload);

                if (!$response['success']) {
                    self::log("Erro template: " . json_encode($response));
                    return $response;
                }

                self::saveMessage($contactId, '[TEMPLATE] ' . $template['name'], $response['message_id']);

                return ['success' => true];
            }

            // =========================
            // BLOQUEIO 24H
            // =========================
            if (!self::isInside24hWindow($contactId)) {
                return [
                    'success' => false,
                    'code' => 'outside_24h',
                    'message' => 'Fora da janela de 24h'
                ];
            }

            // =========================
            // ENVIO NORMAL
            // =========================
            $payload = [
                'messaging_product' => 'whatsapp',
                'to' => $phone,
                'type' => 'text',
                'text' => [
                    'body' => $message
                ]
            ];

            $response = self::sendPayload($settings, $payload);

            if (!$response['success']) {
                self::log("Erro texto: " . json_encode($response));
                return $response;
            }

            self::saveMessage($contactId, $message, $response['message_id']);

            return ['success' => true];

        } catch (Exception $e) {
            self::log($e->getMessage());
            return ['success' => false, 'message' => $e->getMessage()];
        }
    }

    private static function sendPayload($settings, $payload)
    {
        $url = "https://graph.facebook.com/v18.0/" . $settings['phone_number_id'] . "/messages";

        $ch = curl_init($url);

        curl_setopt($ch, CURLOPT_HTTPHEADER, [
            "Authorization: Bearer " . $settings['access_token'],
            "Content-Type: application/json"
        ]);

        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

        $result = curl_exec($ch);
        $http = curl_getinfo($ch, CURLINFO_HTTP_CODE);

        curl_close($ch);

        if ($http >= 200 && $http < 300) {
            $json = json_decode($result, true);
            return [
                'success' => true,
                'message_id' => $json['messages'][0]['id'] ?? null
            ];
        }

        return [
            'success' => false,
            'error' => $result
        ];
    }

    private static function isInside24hWindow($contactId)
    {
        $db = db();

        $stmt = $db->prepare("
            SELECT created_at 
            FROM whatsapp_messages 
            WHERE contact_id = :id 
            AND direction = 'inbound'
            ORDER BY created_at DESC 
            LIMIT 1
        ");

        $stmt->execute(['id' => $contactId]);
        $last = $stmt->fetchColumn();

        if (!$last) return false;

        return (time() - strtotime($last)) <= (60 * 60 * 24);
    }

    private static function saveMessage($contactId, $body, $messageId)
    {
        $db = db();

        $stmt = $db->prepare("
            INSERT INTO whatsapp_messages 
            (contact_id, direction, provider_status, external_message_id, message_body, created_at)
            VALUES (:contact_id, 'outbound', 'sent', :msg_id, :body, NOW())
        ");

        $stmt->execute([
            'contact_id' => $contactId,
            'msg_id' => $messageId,
            'body' => $body
        ]);
    }

    private static function getSettings()
    {
        return [
            'access_token' => getenv('META_ACCESS_TOKEN'),
            'phone_number_id' => getenv('META_PHONE_NUMBER_ID')
        ];
    }

    private static function log($msg)
    {
        file_put_contents(__DIR__ . '/../../storage/logs/whatsapp.log', date('Y-m-d H:i:s') . ' ' . $msg . PHP_EOL, FILE_APPEND);
    }
}