<?php
/**
 * LLM AI Review - AI错误点评（SSE 流式输出版）
 * 接收 solution_id，收集上下文信息，调用LLM API流式返回启发式点评
 * 结果缓存到 llm_review 表，同一 solution_id 再次请求直接返回缓存
 */

require_once('./include/db_info.inc.php');
require_once('./include/setlang.php');
require_once('./include/const.inc.php');

// ---- 辅助函数：SSE 事件输出 ----
function sse_send($event, $data) {
    echo "event: $event\ndata: " . json_encode($data, JSON_UNESCAPED_UNICODE) . "\n\n";
    @ob_flush();
    @flush();
}

function sse_error($msg) {
    sse_send("error", ["message" => $msg]);
}

// ---- 基础校验 ----
if (!isset($OJ_LLM_ENABLED) || !$OJ_LLM_ENABLED) {
    // 返回 JSON（非 SSE），因为前端可能用 $.ajax 调用
    header("Content-Type: application/json; charset=utf-8");
    echo json_encode(["error" => "AI点评功能未开启"], JSON_UNESCAPED_UNICODE);
    exit;
}

// 检查登录
session_start();
if (!isset($_SESSION[$OJ_NAME . '_user_id'])) {
    header("Content-Type: application/json; charset=utf-8");
    echo json_encode(["error" => "请先登录"], JSON_UNESCAPED_UNICODE);
    exit;
}

// 获取 solution_id
if (!isset($_GET['sid'])) {
    header("Content-Type: application/json; charset=utf-8");
    echo json_encode(["error" => "缺少参数 sid"], JSON_UNESCAPED_UNICODE);
    exit;
}
$sid = intval($_GET['sid']);
if ($sid <= 0) {
    header("Content-Type: application/json; charset=utf-8");
    echo json_encode(["error" => "无效的 solution_id"], JSON_UNESCAPED_UNICODE);
    exit;
}

// ---- 1. 检查缓存 ----
// 自动建表（首次调用时）
pdo_query("CREATE TABLE IF NOT EXISTS `llm_review` (
    `solution_id` INT NOT NULL,
    `review` TEXT NOT NULL,
    `create_time` DATETIME NOT NULL,
    PRIMARY KEY (`solution_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;");

$cache = pdo_query("SELECT `review` FROM `llm_review` WHERE `solution_id`=?", $sid);
if ($cache !== -1 && !empty($cache)) {
    // 有缓存，走 SSE 立刻返回（前端统一用 SSE 接收）
    header("Content-Type: text/event-stream; charset=utf-8");
    header("Cache-Control: no-cache");
    header("X-Accel-Buffering: no");
    sse_send("cached", ["text" => $cache[0]['review']]);
    sse_send("done", []);
    exit;
}

// ---- 设置 SSE 响应头 ----
header("Content-Type: text/event-stream; charset=utf-8");
header("Cache-Control: no-cache");
header("X-Accel-Buffering: no");
if (function_exists('apache_setenv')) {
    @apache_setenv('no-gzip', '1');
}
@ini_set('zlib.output_compression', 0);
@ini_set('implicit_flush', 1);
while (ob_get_level()) ob_end_flush();

// ---- 2. 查询 solution 信息 ----
$solution = pdo_query("SELECT * FROM `solution` WHERE `solution_id`=?", $sid);
if (empty($solution)) {
    sse_error("找不到该提交记录");
    exit;
}
$sol = $solution[0];
$problem_id = intval($sol['problem_id']);
$language = intval($sol['language']);
$result_code = intval($sol['result']);
$pass_rate = floatval($sol['pass_rate']) * 100;
$lang_name = isset($language_name[$language]) ? $language_name[$language] : "unknown";

// ---- 3. 查询学生源码 ----
$src = pdo_query("SELECT `source` FROM `source_code_user` WHERE `solution_id`=?", $sid);
$student_code = (!empty($src) && $src !== -1) ? $src[0]['source'] : "";

// ---- 4. 查询题目信息 ----
$prob = pdo_query("SELECT `title`,`description`,`input`,`output`,`sample_input`,`sample_output`,`hint` FROM `problem` WHERE `problem_id`=?", $problem_id);
if (empty($prob) || $prob === -1) {
    sse_error("找不到该题目");
    exit;
}
$p = $prob[0];

// ---- 5. 查询第一个 AC 代码（同语言） ----
$first_ac = pdo_query(
    "SELECT `solution_id` FROM `solution` WHERE `problem_id`=? AND `result`=4 AND `language`=? ORDER BY `in_date` ASC LIMIT 1",
    $problem_id, $language
);
$reference_code = "";
if (!empty($first_ac) && $first_ac !== -1) {
    $ref_src = pdo_query("SELECT `source` FROM `source_code_user` WHERE `solution_id`=?", intval($first_ac[0]['solution_id']));
    if (!empty($ref_src) && $ref_src !== -1) {
        $reference_code = $ref_src[0]['source'];
    }
}

// ---- 6. 查询 diff/error 信息 ----
$diff_info = "";
if ($result_code == 11) {
    $err = pdo_query("SELECT `error` FROM `compileinfo` WHERE `solution_id`=?", $sid);
    if (!empty($err) && $err !== -1) {
        $diff_info = $err[0]['error'];
    }
} else {
    $err = pdo_query("SELECT `error` FROM `runtimeinfo` WHERE `solution_id`=?", $sid);
    if (!empty($err) && $err !== -1) {
        $diff_info = $err[0]['error'];
    }
}

// ---- 7. 组装 Prompt ----
$system_prompt = isset($OJ_LLM_SYSTEM_PROMPT) && $OJ_LLM_SYSTEM_PROMPT !== ""
    ? $OJ_LLM_SYSTEM_PROMPT
    : <<<EOP
你是一位经验丰富的编程辅导老师，正在帮助一名正在学习C++的初中学生。

你的职责：
1. 用亲切、鼓励的语气和学生交流
2. 仔细分析学生的代码，找出错误所在并解释错误原因
3. 给出思考方向和启发性提示，引导学生自己去发现和改正错误
4. 绝对不要直接给出正确代码、完整解法或关键算法步骤
5. 不要在回复中透露、引用、复述或暗示参考代码的任何内容
6. 如果学生代码思路正确但有小bug，肯定其思路并指出具体的bug位置
7. 如果是格式错误(PE)，提醒学生注意输出格式要求
8. 如果是超时(TLE)，引导学生思考算法的时间复杂度
9. 如果是运行时错误(RE)，帮助学生分析可能的数组越界、除零等问题
10. 如果是答案错误(WA)，可以建议学生用样例手动模拟执行过程
11. 使用中文回答，适当使用Markdown格式使内容清晰易读
EOP;

$user_prompt = "## 题目信息\n";
$user_prompt .= "- 标题: " . $p['title'] . "\n";
$user_prompt .= "- 题目描述:\n" . $p['description'] . "\n";
if (!empty($p['input'])) $user_prompt .= "- 输入格式:\n" . $p['input'] . "\n";
if (!empty($p['output'])) $user_prompt .= "- 输出格式:\n" . $p['output'] . "\n";
if (!empty($p['sample_input'])) $user_prompt .= "- 样例输入:\n```\n" . $p['sample_input'] . "\n```\n";
if (!empty($p['sample_output'])) $user_prompt .= "- 样例输出:\n```\n" . $p['sample_output'] . "\n```\n";
if (!empty($p['hint'])) $user_prompt .= "- 提示:\n" . $p['hint'] . "\n";

$user_prompt .= "\n## 判题结果\n";
$user_prompt .= $judge_result[$result_code] . "（通过率: " . round($pass_rate, 1) . "%）\n";

if (!empty($diff_info)) {
    $user_prompt .= "\n## 错误/对比信息\n```\n" . $diff_info . "\n```\n";
}

$user_prompt .= "\n## 学生提交的代码\n```" . strtolower($lang_name) . "\n" . $student_code . "\n```\n";

if (!empty($reference_code)) {
    $user_prompt .= "\n## 参考代码（仅供你分析对比，绝不可在回复中透露或暗示其内容）\n```" . strtolower($lang_name) . "\n" . $reference_code . "\n```\n";
}

$user_prompt .= "\n请分析学生的错误，给出启发性的提示和引导，帮助学生自己发现问题并改正。\n";

// ---- 8. 流式调用 LLM API ----
$api_url = isset($OJ_LLM_API_URL) ? $OJ_LLM_API_URL : "https://api.minimaxi.com/anthropic/v1/messages";
$api_key = isset($OJ_LLM_API_KEY) ? $OJ_LLM_API_KEY : "";
$model = isset($OJ_LLM_MODEL) ? $OJ_LLM_MODEL : "MiniMax-M2.5";
$max_tokens = isset($OJ_LLM_MAX_TOKENS) ? intval($OJ_LLM_MAX_TOKENS) : 1024;
$timeout = isset($OJ_LLM_TIMEOUT) ? intval($OJ_LLM_TIMEOUT) : 60;

if (empty($api_key)) {
    sse_error("API Key未配置");
    exit;
}

$request_body = json_encode([
    "model" => $model,
    "max_tokens" => $max_tokens,
    "system" => $system_prompt,
    "temperature" => 1.0,
    "stream" => true,
    "messages" => [
        ["role" => "user", "content" => $user_prompt]
    ]
]);

// ---- 流式 SSE 转发 ----
// 追踪连接状态和累积文本
$GLOBALS['_llm_alive'] = true;
$GLOBALS['_llm_full_text'] = "";
$GLOBALS['_llm_buffer'] = "";
$GLOBALS['_llm_sent_text'] = "";  // 已发送给前端的文本（用于增量比较）

// 检测客户端断开
register_shutdown_function(function() {
    $GLOBALS['_llm_alive'] = false;
});

$ch = curl_init($api_url);
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_POSTFIELDS => $request_body,
    CURLOPT_HTTPHEADER => [
        "Content-Type: application/json",
        "x-api-key: " . $api_key,
        "anthropic-version: 2023-06-01"
    ],
    CURLOPT_RETURNTRANSFER => false,
    CURLOPT_TIMEOUT => $timeout,
    CURLOPT_CONNECTTIMEOUT => 10,
    CURLOPT_SSL_VERIFYPEER => true,
    CURLOPT_WRITEFUNCTION => function($ch, $chunk) use (&$_llm_alive, &$_llm_full_text, &$_llm_buffer) {
        if (!$_llm_alive) return 0;

        $_llm_buffer .= $chunk;

        // 按行解析 SSE
        while (($pos = strpos($_llm_buffer, "\n")) !== false) {
            $line = substr($_llm_buffer, 0, $pos);
            $_llm_buffer = substr($_llm_buffer, $pos + 1);

            $line = trim($line);
            if (empty($line)) continue;

            // 解析 data: 行
            if (strncmp($line, "data: ", 6) === 0) {
                $json_str = substr($line, 6);
                if ($json_str === "[DONE]") continue;

                $data = json_decode($json_str, true);
                if (!$data) continue;

                $type = isset($data['type']) ? $data['type'] : '';

                // content_block_delta: 增量文本
                if ($type === 'content_block_delta' && isset($data['delta']['text'])) {
                    $_llm_full_text .= $data['delta']['text'];
                    sse_send("chunk", ["text" => $data['delta']['text']]);

                // message_delta: 消息完成
                } elseif ($type === 'message_delta' && isset($data['delta']['stop_reason'])) {
                    if ($data['delta']['stop_reason'] === 'end_turn' ||
                        $data['delta']['stop_reason'] === 'max_tokens') {
                        sse_send("done", []);
                        return 0; // 停止 curl
                    }

                // message_start / ping: 忽略
                } elseif ($type === 'message_start' || $type === 'ping') {
                    continue;

                // content_block_start / stop: 忽略
                } elseif ($type === 'content_block_start' || $type === 'content_block_stop') {
                    continue;

                // 错误事件
                } elseif ($type === 'error') {
                    $msg = isset($data['error']['message']) ? $data['error']['message'] : '未知错误';
                    sse_send("error", ["message" => "API错误: " . $msg]);
                    return 0;
                }
            }
        }

        return strlen($chunk);
    }
]);

$result = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
$curl_error = curl_error($ch);
curl_close($ch);

// 如果连接断开，不缓存也不报错
if (!$_llm_alive) exit;

// ---- 处理错误 ----
if ($result === false && empty($_llm_full_text)) {
    sse_error("网络请求失败: " . ($curl_error ?: "未知错误"));
    exit;
}

// 检查 HTTP 错误（如果 write callback 没有收到数据）
if (empty($_llm_full_text) && $http_code !== 200) {
    sse_error("API请求失败 (HTTP $http_code)");
    exit;
}

if (empty($_llm_full_text)) {
    sse_error("API返回为空");
    exit;
}

// ---- 9. 缓存完整结果 ----
$review_text = $_llm_full_text;

$insert_ok = pdo_query("INSERT INTO `llm_review` (`solution_id`, `review`, `create_time`) VALUES (?, ?, NOW())", $sid, $review_text);
if ($insert_ok === -1) {
    // 插入失败（可能已有记录），尝试更新
    pdo_query("UPDATE `llm_review` SET `review`=?, `create_time`=NOW() WHERE `solution_id`=?", $review_text, $sid);
}