<?php

/**
 * @package     MokoSuiteBackup
 * @subpackage  com_mokosuitebackup
 * @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
 *
 * S3-compatible storage uploader using AWS Signature V4.
 * Works with AWS S3, Wasabi, Backblaze B2, MinIO, and any S3-compatible API.
 * No SDK dependency — pure PHP with cURL.
 */

namespace Joomla\Component\MokoSuiteBackup\Administrator\Engine;

defined('_JEXEC') or die;

class S3Uploader implements RemoteUploaderInterface
{
	private string $endpoint;
	private string $region;
	private string $accessKey;
	private string $secretKey;
	private string $bucket;
	private string $path;

	private const DEFAULT_ENDPOINT = 'https://s3.amazonaws.com';
	private const SERVICE = 's3';

	public function __construct(object $profile)
	{
		$this->endpoint  = rtrim($profile->s3_endpoint ?? '', '/') ?: self::DEFAULT_ENDPOINT;
		$this->region    = $profile->s3_region ?? 'us-east-1';
		$this->accessKey = $profile->s3_access_key ?? '';
		$this->secretKey = $profile->s3_secret_key ?? '';
		$this->bucket    = $profile->s3_bucket ?? '';
		$this->path      = trim($profile->s3_path ?? '/backups', '/');
	}

	public function upload(string $localPath, string $remoteName): array
	{
		if (!extension_loaded('curl')) {
			return ['success' => false, 'message' => 'PHP ext-curl is required for S3 uploads. Enable it in php.ini.'];
		}

		if (empty($this->accessKey) || empty($this->secretKey) || empty($this->bucket)) {
			return ['success' => false, 'message' => 'S3 credentials or bucket not configured'];
		}

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

		try {
			$objectKey = ($this->path ? $this->path . '/' : '') . $remoteName;
			$fileSize  = filesize($localPath);

			// For files > 100 MB use multipart upload, otherwise single PUT
			if ($fileSize > 100 * 1024 * 1024) {
				$this->multipartUpload($localPath, $objectKey, $fileSize);
			} else {
				$this->singleUpload($localPath, $objectKey);
			}

			$remotePath = 's3://' . $this->bucket . '/' . $objectKey;

			return [
				'success'     => true,
				'message'     => 'Uploaded to S3: ' . $remotePath,
				'remote_path' => $remotePath,
			];
		} catch (\Throwable $e) {
			return ['success' => false, 'message' => 'S3 upload failed: ' . $e->getMessage()];
		}
	}

	public function testConnection(): array
	{
		if (empty($this->accessKey) || empty($this->secretKey) || empty($this->bucket)) {
			return ['success' => false, 'message' => 'S3 credentials or bucket not configured'];
		}

		try {
			// HEAD bucket to test access
			$url     = $this->getBucketUrl();
			$headers = $this->signRequest('HEAD', $url, '');

			$ch = curl_init();
			curl_setopt_array($ch, [
				CURLOPT_URL            => $url,
				CURLOPT_NOBODY         => true,
				CURLOPT_RETURNTRANSFER => true,
				CURLOPT_HTTPHEADER     => $headers,
				CURLOPT_TIMEOUT        => 30,
			]);

			curl_exec($ch);
			$code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
			curl_close($ch);

			if ($code === 200 || $code === 301) {
				return ['success' => true, 'message' => 'Connected to S3 bucket: ' . $this->bucket];
			}

			return ['success' => false, 'message' => 'S3 returned HTTP ' . $code . ' for bucket ' . $this->bucket];
		} catch (\Throwable $e) {
			return ['success' => false, 'message' => 'Connection test failed: ' . $e->getMessage()];
		}
	}

	/**
	 * Single PUT upload for files <= 100 MB.
	 */
	private function singleUpload(string $localPath, string $objectKey): void
	{
		$url         = $this->getObjectUrl($objectKey);
		$fileContent = file_get_contents($localPath);
		$contentHash = hash('sha256', $fileContent);
		$headers     = $this->signRequest('PUT', $url, $contentHash, [
			'Content-Type'   => 'application/zip',
			'Content-Length' => (string) strlen($fileContent),
		]);

		$ch = curl_init();
		curl_setopt_array($ch, [
			CURLOPT_URL            => $url,
			CURLOPT_CUSTOMREQUEST  => 'PUT',
			CURLOPT_POSTFIELDS     => $fileContent,
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_HTTPHEADER     => $headers,
			CURLOPT_TIMEOUT        => 600,
		]);

		$response = curl_exec($ch);
		$code     = curl_getinfo($ch, CURLINFO_HTTP_CODE);

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

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

		curl_close($ch);

		if ($code < 200 || $code >= 300) {
			throw new \RuntimeException('S3 PUT failed (HTTP ' . $code . '): ' . substr($response, 0, 500));
		}
	}

	/**
	 * Multipart upload for files > 100 MB.
	 */
	private function multipartUpload(string $localPath, string $objectKey, int $fileSize): void
	{
		$chunkSize = 10 * 1024 * 1024; // 10 MB parts

		// Step 1: Initiate multipart upload
		$uploadId = $this->initiateMultipart($objectKey);

		$handle = fopen($localPath, 'rb');

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

		$parts  = [];
		$partNum = 1;

		try {
			// Step 2: Upload parts
			while (!feof($handle)) {
				$chunk = fread($handle, $chunkSize);

				if ($chunk === false || $chunk === '') {
					break;
				}

				$etag = $this->uploadPart($objectKey, $uploadId, $partNum, $chunk);
				$parts[] = ['PartNumber' => $partNum, 'ETag' => $etag];
				$partNum++;
			}

			fclose($handle);

			// Step 3: Complete multipart upload
			$this->completeMultipart($objectKey, $uploadId, $parts);
		} catch (\Throwable $e) {
			fclose($handle);
			// Abort the multipart upload on failure
			$this->abortMultipart($objectKey, $uploadId);

			throw $e;
		}
	}

	private function initiateMultipart(string $objectKey): string
	{
		$url         = $this->getObjectUrl($objectKey) . '?uploads';
		$contentHash = hash('sha256', '');
		$headers     = $this->signRequest('POST', $url, $contentHash, [
			'Content-Type' => 'application/zip',
		]);

		$ch = curl_init();
		curl_setopt_array($ch, [
			CURLOPT_URL            => $url,
			CURLOPT_POST           => true,
			CURLOPT_POSTFIELDS     => '',
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_HTTPHEADER     => $headers,
			CURLOPT_TIMEOUT        => 60,
		]);

		$response = curl_exec($ch);
		$code     = curl_getinfo($ch, CURLINFO_HTTP_CODE);
		curl_close($ch);

		if ($code < 200 || $code >= 300) {
			throw new \RuntimeException('Initiate multipart failed (HTTP ' . $code . ')');
		}

		// Parse UploadId from XML response
		preg_match('/<UploadId>([^<]+)<\/UploadId>/', $response, $matches);

		if (empty($matches[1])) {
			throw new \RuntimeException('No UploadId in initiate response');
		}

		return $matches[1];
	}

	private function uploadPart(string $objectKey, string $uploadId, int $partNumber, string $data): string
	{
		$url         = $this->getObjectUrl($objectKey) . '?partNumber=' . $partNumber . '&uploadId=' . urlencode($uploadId);
		$contentHash = hash('sha256', $data);
		$headers     = $this->signRequest('PUT', $url, $contentHash, [
			'Content-Length' => (string) strlen($data),
		]);

		$ch = curl_init();
		curl_setopt_array($ch, [
			CURLOPT_URL            => $url,
			CURLOPT_CUSTOMREQUEST  => 'PUT',
			CURLOPT_POSTFIELDS     => $data,
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_HTTPHEADER     => $headers,
			CURLOPT_HEADERFUNCTION => function ($ch, $header) use (&$etag) {
				if (stripos($header, 'ETag:') === 0) {
					$etag = trim(substr($header, 5));
				}

				return strlen($header);
			},
			CURLOPT_TIMEOUT        => 300,
		]);

		$etag = '';
		curl_exec($ch);
		$code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
		curl_close($ch);

		if ($code < 200 || $code >= 300) {
			throw new \RuntimeException('Upload part ' . $partNumber . ' failed (HTTP ' . $code . ')');
		}

		return $etag;
	}

	private function completeMultipart(string $objectKey, string $uploadId, array $parts): void
	{
		$xml = '<CompleteMultipartUpload>';

		foreach ($parts as $part) {
			$xml .= '<Part>'
				. '<PartNumber>' . $part['PartNumber'] . '</PartNumber>'
				. '<ETag>' . $part['ETag'] . '</ETag>'
				. '</Part>';
		}

		$xml .= '</CompleteMultipartUpload>';

		$url         = $this->getObjectUrl($objectKey) . '?uploadId=' . urlencode($uploadId);
		$contentHash = hash('sha256', $xml);
		$headers     = $this->signRequest('POST', $url, $contentHash, [
			'Content-Type'   => 'application/xml',
			'Content-Length' => (string) strlen($xml),
		]);

		$ch = curl_init();
		curl_setopt_array($ch, [
			CURLOPT_URL            => $url,
			CURLOPT_POST           => true,
			CURLOPT_POSTFIELDS     => $xml,
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_HTTPHEADER     => $headers,
			CURLOPT_TIMEOUT        => 60,
		]);

		$response = curl_exec($ch);
		$code     = curl_getinfo($ch, CURLINFO_HTTP_CODE);
		curl_close($ch);

		if ($code < 200 || $code >= 300) {
			throw new \RuntimeException('Complete multipart failed (HTTP ' . $code . '): ' . substr($response, 0, 500));
		}
	}

	private function abortMultipart(string $objectKey, string $uploadId): void
	{
		$url         = $this->getObjectUrl($objectKey) . '?uploadId=' . urlencode($uploadId);
		$contentHash = hash('sha256', '');
		$headers     = $this->signRequest('DELETE', $url, $contentHash);

		$ch = curl_init();
		curl_setopt_array($ch, [
			CURLOPT_URL            => $url,
			CURLOPT_CUSTOMREQUEST  => 'DELETE',
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_HTTPHEADER     => $headers,
			CURLOPT_TIMEOUT        => 30,
		]);

		curl_exec($ch);
		curl_close($ch);
	}

	// ── AWS Signature V4 ───────────────────────────────────────────

	/**
	 * Sign a request using AWS Signature V4.
	 *
	 * @return  string[]  Array of HTTP headers ready for cURL
	 */
	private function signRequest(string $method, string $url, string $payloadHash, array $extraHeaders = []): array
	{
		$parsed   = parse_url($url);
		$host     = $parsed['host'] . (isset($parsed['port']) ? ':' . $parsed['port'] : '');
		$path     = $parsed['path'] ?? '/';
		$query    = $parsed['query'] ?? '';

		$now      = gmdate('Ymd\THis\Z');
		$dateOnly = gmdate('Ymd');
		$scope    = $dateOnly . '/' . $this->region . '/' . self::SERVICE . '/aws4_request';

		// Canonical headers
		$headers = array_merge([
			'host'                 => $host,
			'x-amz-content-sha256' => $payloadHash,
			'x-amz-date'          => $now,
		], array_change_key_case($extraHeaders, CASE_LOWER));

		ksort($headers);

		$signedHeaders    = implode(';', array_keys($headers));
		$canonicalHeaders = '';

		foreach ($headers as $k => $v) {
			$canonicalHeaders .= $k . ':' . trim($v) . "\n";
		}

		// Canonical query string (sorted)
		$queryParts = [];

		if (!empty($query)) {
			parse_str($query, $qp);
			ksort($qp);

			foreach ($qp as $k => $v) {
				$queryParts[] = rawurlencode($k) . '=' . rawurlencode($v);
			}
		}

		$canonicalQuery = implode('&', $queryParts);

		// Canonical request
		$canonicalRequest = implode("\n", [
			$method,
			$path,
			$canonicalQuery,
			$canonicalHeaders,
			$signedHeaders,
			$payloadHash,
		]);

		// String to sign
		$stringToSign = implode("\n", [
			'AWS4-HMAC-SHA256',
			$now,
			$scope,
			hash('sha256', $canonicalRequest),
		]);

		// Signing key
		$kDate    = hash_hmac('sha256', $dateOnly, 'AWS4' . $this->secretKey, true);
		$kRegion  = hash_hmac('sha256', $this->region, $kDate, true);
		$kService = hash_hmac('sha256', self::SERVICE, $kRegion, true);
		$kSigning = hash_hmac('sha256', 'aws4_request', $kService, true);

		$signature = hash_hmac('sha256', $stringToSign, $kSigning);

		// Authorization header
		$authHeader = 'AWS4-HMAC-SHA256 '
			. 'Credential=' . $this->accessKey . '/' . $scope . ', '
			. 'SignedHeaders=' . $signedHeaders . ', '
			. 'Signature=' . $signature;

		// Build cURL header array
		$curlHeaders = [
			'Authorization: ' . $authHeader,
			'x-amz-content-sha256: ' . $payloadHash,
			'x-amz-date: ' . $now,
		];

		foreach ($extraHeaders as $k => $v) {
			$curlHeaders[] = $k . ': ' . $v;
		}

		return $curlHeaders;
	}

	private function getBucketUrl(): string
	{
		if ($this->endpoint === self::DEFAULT_ENDPOINT) {
			return 'https://' . $this->bucket . '.s3.' . $this->region . '.amazonaws.com/';
		}

		// Path-style for custom endpoints (MinIO, Wasabi, B2)
		return rtrim($this->endpoint, '/') . '/' . $this->bucket . '/';
	}

	private function getObjectUrl(string $objectKey): string
	{
		if ($this->endpoint === self::DEFAULT_ENDPOINT) {
			return 'https://' . $this->bucket . '.s3.' . $this->region . '.amazonaws.com/' . ltrim($objectKey, '/');
		}

		return rtrim($this->endpoint, '/') . '/' . $this->bucket . '/' . ltrim($objectKey, '/');
	}
}