<?php

namespace app\common;

use think\Env;
use think\Exception;

/**
 * Turnitin Core API (TCA) REST 客户端封装。
 *
 * 适用 Crossref Similarity Check 通道（product_name=Crossref）以及标准 TCA 接入。
 *
 * 鉴权：Authorization: Bearer <API_KEY>
 *       X-Turnitin-Integration-Name / X-Turnitin-Integration-Version 用于审计
 *
 * .env 配置（[turnitin] 段）:
 *   BASE_URL              形如 https://crossref-12345.turnitin.com/api/v1（不带尾斜杠）
 *   API_KEY               生成的 Bearer token
 *   INTEGRATION_NAME      Scope Name（创建 integration 时填的名字）
 *   INTEGRATION_VERSION   自定义版本号，便于审计 e.g. 1.0.0
 *
 * API 文档：https://developers.turnitin.com/docs/tca
 *
 * 注意：
 *   - 所有方法返回原始 decode 后的数组；HTTP 错误抛 Exception
 *   - 不做任何业务层逻辑（业务层在 PlagiarismService 里）
 *   - 不缓存 token（Bearer 不需要登录，每次请求自带）
 */
class TurnitinService
{
    private $baseUrl;
    private $apiKey;
    private $integrationName;
    private $integrationVersion;
    private $timeout = 60;

    public function __construct()
    {
        $this->baseUrl            = rtrim(trim((string)Env::get('turnitin.base_url', '')), '/');
        $this->apiKey             = trim((string)Env::get('turnitin.api_key', ''));
        $this->integrationName    = trim((string)Env::get('turnitin.integration_name', 'tmr'));
        $this->integrationVersion = trim((string)Env::get('turnitin.integration_version', '1.0.0'));

        if ($this->baseUrl === '' || $this->apiKey === '') {
            throw new Exception('Turnitin not configured: missing BASE_URL or API_KEY in .env [turnitin] section');
        }
    }

    // ==================== Public API ====================

    /**
     * 探活 / 拿账户能力
     * GET /features-enabled
     */
    public function featuresEnabled()
    {
        return $this->request('GET', '/features-enabled');
    }

    /**
     * 创建 submission（拿到 id 之后才能上传文件）
     * POST /submissions
     *
     * @param array $meta 必填字段:
     *   - title           论文标题
     *   - owner           submission owner 标识符（自定义字符串，比如投稿系统 user_id）
     *   - submitter       提交者标识符（同上）
     *   - eula            (可选) ['version' => '...', 'language' => 'en-US', 'accepted_timestamp' => ISO8601]
     *                     如果 features-enabled 返回 require_eula=false 可省略
     *   可选字段:
     *   - extract_text_only  bool
     *   - metadata           array  自定义键值，供后续追溯
     *
     * @return array 含 id（submission UUID）, status, owner, ...
     */
    public function createSubmission($meta)
    {
        return $this->request('POST', '/submissions', $meta);
    }

    /**
     * 上传文件到 submission
     * PUT /submissions/{id}/original/{filename}
     *
     * @param string $submissionId
     * @param string $filePath  本地 PDF/DOCX 路径
     * @param string $filename  传给 Turnitin 的文件名（用于报告显示）
     * @return array
     */
    public function uploadFile($submissionId, $filePath, $filename = '')
    {
        if (!is_file($filePath) || !is_readable($filePath)) {
            throw new Exception("File not found or not readable: {$filePath}");
        }
        if ($filename === '') {
            $filename = basename($filePath);
        }
        $body = file_get_contents($filePath);

        return $this->request(
            'PUT',
            '/submissions/' . urlencode($submissionId) . '/original/' . rawurlencode($filename),
            $body,
            [
                'Content-Type'              => 'binary/octet-stream',
                'Content-Disposition'       => 'inline; filename="' . $filename . '"',
            ]
        );
    }

    /**
     * 触发 similarity 比对
     * PUT /submissions/{id}/similarity
     *
     * @param string $submissionId
     * @param array  $opts
     *   - generation_settings.search_repositories  默认 ['INTERNET','PUBLICATION','CROSSREF','CROSSREF_POSTED_CONTENT','SUBMITTED_WORK']
     *   - generation_settings.submission_auto_excludes  bool
     *   - view_settings.exclude_quotes / exclude_bibliography / exclude_citations / exclude_abstract / exclude_methods  bool
     *   - indexing_settings.add_to_index  bool 是否把本文加进 SUBMITTED_WORK 索引（一般 true）
     * @return array
     */
    public function triggerSimilarity($submissionId, $opts = [])
    {
        $body = array_merge([
            'generation_settings' => [
                'search_repositories' => ['INTERNET', 'PUBLICATION', 'CROSSREF', 'CROSSREF_POSTED_CONTENT', 'SUBMITTED_WORK'],
                'submission_auto_excludes' => true,
                'auto_exclude_self_matching_scope' => 'GROUP_CONTEXT',
            ],
            'view_settings' => [
                'exclude_quotes'        => true,
                'exclude_bibliography'  => true,
                'exclude_citations'     => true,
            ],
            'indexing_settings' => [
                'add_to_index' => true,
            ],
        ], $opts);

        return $this->request(
            'PUT',
            '/submissions/' . urlencode($submissionId) . '/similarity',
            $body
        );
    }

    /**
     * 查询 similarity 状态
     * GET /submissions/{id}/similarity
     *
     * 返回 status: PROCESSING / COMPLETE / ERROR
     * COMPLETE 时返回 overall_match_percentage / time_requested / time_generated
     */
    public function getSimilarityStatus($submissionId)
    {
        return $this->request(
            'GET',
            '/submissions/' . urlencode($submissionId) . '/similarity'
        );
    }

    /**
     * 取在线查看报告的临时 URL
     * POST /submissions/{id}/viewer-url
     *
     * 返回 viewer_url（数小时有效）
     *
     * @param array $viewer 可选 viewer 设置 e.g. ['viewer_default_permission_set' => 'INSTRUCTOR']
     */
    public function getViewerUrl($submissionId, $viewer = [])
    {
        $body = array_merge([
            'viewer_default_permission_set' => 'INSTRUCTOR',
            'similarity' => [
                'default_mode' => 'MATCH_OVERVIEW',
                'view_settings' => ['save_changes' => true],
                'modes' => ['match_overview' => true, 'all_sources' => true],
            ],
            'locale' => 'en-US',
        ], $viewer);

        return $this->request(
            'POST',
            '/submissions/' . urlencode($submissionId) . '/viewer-url',
            $body
        );
    }

    /**
     * 触发生成 PDF 报告（异步，状态在另一个轮询里看）
     * POST /submissions/{id}/similarity/pdf
     *
     * 返回 id（pdf 报告 ID）
     */
    public function requestPdfReport($submissionId, $opts = [])
    {
        $body = array_merge([
            'locale' => 'en-US',
        ], $opts);

        return $this->request(
            'POST',
            '/submissions/' . urlencode($submissionId) . '/similarity/pdf',
            $body
        );
    }

    /**
     * 查询 PDF 报告状态
     * GET /submissions/{id}/similarity/pdf/{pdf_id}/status
     *
     * status: PENDING / SUCCESS / FAILED
     */
    public function getPdfReportStatus($submissionId, $pdfId)
    {
        return $this->request(
            'GET',
            '/submissions/' . urlencode($submissionId) . '/similarity/pdf/' . urlencode($pdfId) . '/status'
        );
    }

    /**
     * 下载 PDF 报告内容（status=SUCCESS 后才可调用）
     * GET /submissions/{id}/similarity/pdf/{pdf_id}
     *
     * 返回 raw PDF binary 字符串；调用方负责落盘
     */
    public function downloadPdfReport($submissionId, $pdfId)
    {
        return $this->request(
            'GET',
            '/submissions/' . urlencode($submissionId) . '/similarity/pdf/' . urlencode($pdfId),
            null,
            [],
            true   // raw response (不 json_decode)
        );
    }

    // ==================== Internal HTTP layer ====================

    /**
     * 统一 HTTP 调用
     *
     * @param string      $method      GET/POST/PUT/DELETE
     * @param string      $path        以 / 开头的相对路径，会拼到 baseUrl 后
     * @param mixed       $body        array 时按 JSON 编码；string 时直接当 raw body
     * @param array       $extraHeaders 额外 header
     * @param bool        $rawResponse  true=返回 raw 字符串；false=json_decode
     * @return mixed
     * @throws Exception
     */
    private function request($method, $path, $body = null, $extraHeaders = [], $rawResponse = false)
    {
        $url = $this->baseUrl . $path;

        $headers = [
            'Authorization: Bearer ' . $this->apiKey,
            'X-Turnitin-Integration-Name: '    . $this->integrationName,
            'X-Turnitin-Integration-Version: ' . $this->integrationVersion,
        ];

        $payload = null;
        if ($body !== null) {
            if (is_array($body)) {
                $payload = json_encode($body, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
                $headers[] = 'Content-Type: application/json';
            } else {
                $payload = $body;
                if (!isset($extraHeaders['Content-Type'])) {
                    $headers[] = 'Content-Type: application/octet-stream';
                }
            }
        }
        foreach ($extraHeaders as $k => $v) {
            $headers[] = $k . ': ' . $v;
        }

        $ch = curl_init();
        curl_setopt_array($ch, [
            CURLOPT_URL            => $url,
            CURLOPT_CUSTOMREQUEST  => strtoupper($method),
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_HTTPHEADER     => $headers,
            CURLOPT_TIMEOUT        => $this->timeout,
            CURLOPT_CONNECTTIMEOUT => 15,
            CURLOPT_SSL_VERIFYPEER => true,
            CURLOPT_SSL_VERIFYHOST => 2,
        ]);
        if ($payload !== null) {
            curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
        }

        $resp     = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $err      = curl_error($ch);
        curl_close($ch);

        if ($resp === false) {
            throw new Exception("Turnitin curl error: {$err} (url={$url})");
        }
        if ($httpCode < 200 || $httpCode >= 300) {
            // 把响应体的前 1k 也带上方便排错
            $excerpt = mb_substr((string)$resp, 0, 1000);
            throw new Exception("Turnitin HTTP {$httpCode} {$method} {$path}: {$excerpt}");
        }

        if ($rawResponse) {
            return $resp;
        }
        // 部分响应可能是 204 No Content
        if ($resp === '' || $resp === null) {
            return [];
        }
        $data = json_decode($resp, true);
        if (json_last_error() !== JSON_ERROR_NONE) {
            // 不是 JSON 也直接抛回原文
            return $resp;
        }
        return $data;
    }
}