<?php

/**
 * @package     MokoJoomBackup
 * @subpackage  com_mokojoombackup
 * @author      Moko Consulting <hello@mokoconsulting.tech>
 * @copyright   Copyright (C) 2026 Moko Consulting. All rights reserved.
 * @license     GNU General Public License version 3 or later; see LICENSE
 *
 * Google Drive uploader using REST API with OAuth2 refresh tokens.
 * Uses the resumable upload endpoint for reliable large-file uploads.
 * No SDK dependency — pure PHP with cURL.
 */

namespace Joomla\Component\MokoJoomBackup\Administrator\Engine;

defined('_JEXEC') or die;

class GoogleDriveUploader implements RemoteUploaderInterface
{
	private const TOKEN_URL  = 'https://oauth2.googleapis.com/token';
	private const UPLOAD_URL = 'https://www.googleapis.com/upload/drive/v3/files';
	private const API_URL    = 'https://www.googleapis.com/drive/v3';

	private string $clientId;
	private string $clientSecret;
	private string $refreshToken;
	private string $folderId;

	public function __construct(object $profile)
	{
		$this->clientId     = $profile->gdrive_client_id ?? '';
		$this->clientSecret = $profile->gdrive_client_secret ?? '';
		$this->refreshToken = $profile->gdrive_refresh_token ?? '';
		$this->folderId     = $profile->gdrive_folder_id ?? '';
	}

	public function upload(string $localPath, string $remoteName): array
	{
		if (!extension_loaded('curl')) {
			return ['success' => false, 'message' => 'PHP ext-curl is required for Google Drive uploads. Enable it in php.ini.'];
		}

		if (empty($this->clientId) || empty($this->refreshToken)) {
			return ['success' => false, 'message' => 'Google Drive credentials not configured'];
		}

		if (!is_file($localPath) || !is_readable($localPath)) {
			return ['success' => false, 'message' => 'Local file not readable: ' . $localPath];
		}

		try {
			// Step 1: Get fresh access token
			$accessToken = $this->getAccessToken();

			// Step 2: Initiate resumable upload
			$fileSize = filesize($localPath);
			$mimeType = 'application/zip';

			$metadata = [
				'name'     => $remoteName,
				'mimeType' => $mimeType,
			];

			if (!empty($this->folderId)) {
				$metadata['parents'] = [$this->folderId];
			}

			$uploadUri = $this->initiateResumableUpload($accessToken, $metadata, $fileSize, $mimeType);

			// Step 3: Upload file content in chunks
			$this->uploadFileContent($uploadUri, $localPath, $fileSize, $mimeType);

			return [
				'success'     => true,
				'message'     => 'Uploaded to Google Drive: ' . $remoteName,
				'remote_path' => 'gdrive://' . ($this->folderId ?: 'root') . '/' . $remoteName,
			];
		} catch (\Throwable $e) {
			return ['success' => false, 'message' => 'Google Drive upload failed: ' . $e->getMessage()];
		}
	}

	public function testConnection(): array
	{
		if (empty($this->clientId) || empty($this->refreshToken)) {
			return ['success' => false, 'message' => 'Google Drive credentials not configured'];
		}

		try {
			$accessToken = $this->getAccessToken();

			// Test by listing the target folder (or root)
			$url = self::API_URL . '/about?fields=user';

			$response = $this->curlRequest('GET', $url, null, [
				'Authorization: Bearer ' . $accessToken,
			]);

			if ($response['code'] !== 200) {
				throw new \RuntimeException('API returned HTTP ' . $response['code']);
			}

			$data = json_decode($response['body'], true);
			$email = $data['user']['emailAddress'] ?? 'unknown';

			return [
				'success' => true,
				'message' => 'Connected to Google Drive as ' . $email,
			];
		} catch (\Throwable $e) {
			return ['success' => false, 'message' => 'Connection test failed: ' . $e->getMessage()];
		}
	}

	/**
	 * Exchange the refresh token for a fresh access token.
	 */
	private function getAccessToken(): string
	{
		$response = $this->curlRequest('POST', self::TOKEN_URL, http_build_query([
			'client_id'     => $this->clientId,
			'client_secret' => $this->clientSecret,
			'refresh_token' => $this->refreshToken,
			'grant_type'    => 'refresh_token',
		]), [
			'Content-Type: application/x-www-form-urlencoded',
		]);

		if ($response['code'] !== 200) {
			throw new \RuntimeException('Token refresh failed (HTTP ' . $response['code'] . '): ' . $response['body']);
		}

		$data = json_decode($response['body'], true);

		if (empty($data['access_token'])) {
			throw new \RuntimeException('No access_token in token response');
		}

		return $data['access_token'];
	}

	/**
	 * Initiate a resumable upload session with Google Drive.
	 *
	 * @return  string  The resumable upload URI
	 */
	private function initiateResumableUpload(string $accessToken, array $metadata, int $fileSize, string $mimeType): string
	{
		$url = self::UPLOAD_URL . '?uploadType=resumable';

		$response = $this->curlRequest('POST', $url, json_encode($metadata), [
			'Authorization: Bearer ' . $accessToken,
			'Content-Type: application/json; charset=UTF-8',
			'X-Upload-Content-Type: ' . $mimeType,
			'X-Upload-Content-Length: ' . $fileSize,
		], true);

		if ($response['code'] !== 200) {
			throw new \RuntimeException('Failed to initiate upload (HTTP ' . $response['code'] . '): ' . $response['body']);
		}

		if (empty($response['headers']['location'])) {
			throw new \RuntimeException('No upload URI in response headers');
		}

		return $response['headers']['location'];
	}

	/**
	 * Upload file content to the resumable upload URI in chunks.
	 */
	private function uploadFileContent(string $uploadUri, string $localPath, int $fileSize, string $mimeType): void
	{
		$chunkSize = 5 * 1024 * 1024; // 5 MB chunks
		$handle    = fopen($localPath, 'rb');

		if ($handle === false) {
			throw new \RuntimeException('Cannot open file for reading: ' . $localPath);
		}

		try {
			$offset = 0;

			while ($offset < $fileSize) {
				$remaining = $fileSize - $offset;
				$length    = min($chunkSize, $remaining);
				$chunk     = fread($handle, $length);

				if ($chunk === false) {
					throw new \RuntimeException('Failed to read file at offset ' . $offset);
				}

				$rangeEnd = $offset + $length - 1;

				$response = $this->curlRequest('PUT', $uploadUri, $chunk, [
					'Content-Type: ' . $mimeType,
					'Content-Length: ' . $length,
					'Content-Range: bytes ' . $offset . '-' . $rangeEnd . '/' . $fileSize,
				]);

				// 308 = Resume Incomplete (more chunks needed), 200/201 = complete
				if ($response['code'] !== 200 && $response['code'] !== 201 && $response['code'] !== 308) {
					throw new \RuntimeException(
						'Chunk upload failed at offset ' . $offset . ' (HTTP ' . $response['code'] . '): ' . $response['body']
					);
				}

				$offset += $length;
			}
		} finally {
			fclose($handle);
		}
	}

	/**
	 * Execute a cURL request.
	 *
	 * @param   string       $method          HTTP method
	 * @param   string       $url             Request URL
	 * @param   string|null  $body            Request body
	 * @param   array        $headers         Request headers
	 * @param   bool         $captureHeaders  Whether to capture response headers
	 *
	 * @return  array{code: int, body: string, headers?: array}
	 */
	private function curlRequest(string $method, string $url, ?string $body, array $headers, bool $captureHeaders = false): array
	{
		$ch = curl_init();

		curl_setopt_array($ch, [
			CURLOPT_URL            => $url,
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_TIMEOUT        => 300,
			CURLOPT_CONNECTTIMEOUT => 30,
			CURLOPT_HTTPHEADER     => $headers,
			CURLOPT_CUSTOMREQUEST  => $method,
		]);

		if ($body !== null) {
			curl_setopt($ch, CURLOPT_POSTFIELDS, $body);
		}

		$responseHeaders = [];

		if ($captureHeaders) {
			curl_setopt($ch, CURLOPT_HEADERFUNCTION, function ($ch, $header) use (&$responseHeaders) {
				$parts = explode(':', $header, 2);

				if (count($parts) === 2) {
					$responseHeaders[strtolower(trim($parts[0]))] = trim($parts[1]);
				}

				return strlen($header);
			});
		}

		$responseBody = curl_exec($ch);
		$httpCode     = curl_getinfo($ch, CURLINFO_HTTP_CODE);

		if (curl_errno($ch)) {
			$error = curl_error($ch);
			curl_close($ch);

			throw new \RuntimeException('cURL error: ' . $error);
		}

		curl_close($ch);

		$result = ['code' => $httpCode, 'body' => $responseBody];

		if ($captureHeaders) {
			$result['headers'] = $responseHeaders;
		}

		return $result;
	}
}