<?php

namespace app\service;

use app\model\AiModel;
use think\exception\HttpResponseException;

class OpenAIService
{
    public static function getModel(?int $modelId = null): AiModel
    {
        if ($modelId) {
            $model = AiModel::where('id', $modelId)->where('enabled', 1)->find();
        } else {
            $model = AiModel::where('is_default', 1)->where('enabled', 1)->find();
        }

        if (!$model) {
            $model = AiModel::where('enabled', 1)->order('sort_order')->find();
        }

        if (!$model) {
            throw new HttpResponseException(json([
                'code'    => 1,
                'message' => '未配置可用的 AI 模型',
                'data'    => null,
            ], 500));
        }

        return $model;
    }

    public static function getLanguageModel(?int $preferredModelId = null): AiModel
    {
        $model = null;
        if ($preferredModelId) {
            $model = AiModel::where('id', $preferredModelId)
                ->where('enabled', 1)
                ->where('provider', '<>', 'comfy')
                ->find();
        }

        if (!$model) {
            $model = AiModel::where('enabled', 1)
                ->where('provider', '<>', 'comfy')
                ->order('is_default', 'desc')
                ->order('sort_order')
                ->find();
        }

        if (!$model) {
            self::throwUnavailableModel('未配置可用的语言模型，Agent 暂时无法处理文本任务');
        }

        return $model;
    }

    public static function getImageModel(?int $preferredModelId = null): AiModel
    {
        $model = null;
        if ($preferredModelId) {
            $model = AiModel::where('id', $preferredModelId)
                ->where('enabled', 1)
                ->where('provider', 'comfy')
                ->find();
        }

        if (!$model) {
            $model = AiModel::where('enabled', 1)
                ->where('provider', 'comfy')
                ->order('is_default', 'desc')
                ->order('sort_order')
                ->find();
        }

        if (!$model) {
            self::throwUnavailableModel('未配置可用的图片生成模型，Agent 暂时无法生成图片');
        }

        return $model;
    }

    private static function throwUnavailableModel(string $message): void
    {
        throw new HttpResponseException(json([
            'code'    => 1,
            'message' => $message,
            'data'    => null,
        ], 503));
    }

    /**
     * frequency_penalty / presence_penalty 是 OpenAI 协议标准参数，vLLM/SGLang 等
     * OpenAI 兼容服务通常都支持。部分自部署模型（尤其是 OCR/文档解析类模型）在纯文本
     * 对话场景下容易陷入重复输出循环，通过这两个参数可以有效抑制。仅在管理员配置了
     * 非零值时才带上，避免影响已经正常工作的模型。
     */
    private static function penaltyParams(AiModel $model): array
    {
        $params = [];
        $frequencyPenalty = (float) ($model->frequency_penalty ?? 0);
        $presencePenalty = (float) ($model->presence_penalty ?? 0);

        if ($frequencyPenalty !== 0.0) {
            $params['frequency_penalty'] = $frequencyPenalty;
        }
        if ($presencePenalty !== 0.0) {
            $params['presence_penalty'] = $presencePenalty;
        }

        return $params;
    }

    public static function streamChat(AiModel $model, array $messages, callable $onChunk, ?callable $onError = null): void
    {
        $url = rtrim($model->api_base_url, '/') . '/chat/completions';
        $payload = array_merge([
            'model'       => $model->model_id,
            'messages'    => $messages,
            'stream'      => true,
            'max_tokens'  => (int) $model->max_tokens,
            'temperature' => (float) $model->temperature,
        ], self::penaltyParams($model));

        $errorBody = '';
        $httpCode = 0;

        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_POST           => true,
            CURLOPT_POSTFIELDS     => json_encode($payload),
            CURLOPT_HTTPHEADER     => [
                'Content-Type: application/json',
                'Authorization: Bearer ' . $model->api_key,
            ],
            CURLOPT_RETURNTRANSFER => false,
            CURLOPT_HEADERFUNCTION => function ($ch, $header) use (&$httpCode) {
                if (preg_match('/^HTTP\/\d+\.\d+\s+(\d+)/', $header, $m)) {
                    $httpCode = (int) $m[1];
                }
                return strlen($header);
            },
            CURLOPT_WRITEFUNCTION  => function ($ch, $data) use (&$errorBody, &$httpCode, $onChunk) {
                if ($httpCode >= 400) {
                    $errorBody .= $data;
                    return strlen($data);
                }

                $lines = explode("\n", $data);
                foreach ($lines as $line) {
                    $line = trim($line);
                    if ($line === '' || $line === 'data: [DONE]') {
                        continue;
                    }
                    if (str_starts_with($line, 'data: ')) {
                        $json = json_decode(substr($line, 6), true);
                        if ($json) {
                            if (!empty($json['error']['message'])) {
                                throw new \RuntimeException($json['error']['message']);
                            }
                            $onChunk($json);
                        }
                    }
                }
                return strlen($data);
            },
            CURLOPT_TIMEOUT        => 120,
            CURLOPT_CONNECTTIMEOUT => 15,
            CURLOPT_SSL_VERIFYPEER => false,
        ]);

        try {
            $result = curl_exec($ch);
            if ($result === false) {
                $message = 'AI 请求失败: ' . curl_error($ch);
                if ($onError) {
                    $onError($message);
                } else {
                    self::sseEvent('error', ['message' => $message]);
                }
                curl_close($ch);
                return;
            }

            if ($httpCode >= 400) {
                $detail = self::parseErrorBody($errorBody) ?: ('HTTP ' . $httpCode);
                $message = 'AI 请求失败: ' . $detail;
                if ($onError) {
                    $onError($message);
                } else {
                    self::sseEvent('error', ['message' => $message]);
                }
            }
        } catch (\Throwable $e) {
            if ($onError) {
                $onError($e->getMessage());
            } else {
                self::sseEvent('error', ['message' => $e->getMessage()]);
            }
        } finally {
            curl_close($ch);
        }
    }

    public static function chat(AiModel $model, array $messages): array
    {
        $url = rtrim($model->api_base_url, '/') . '/chat/completions';
        $payload = array_merge([
            'model'       => $model->model_id,
            'messages'    => $messages,
            'stream'      => false,
            'max_tokens'  => (int) $model->max_tokens,
            'temperature' => (float) $model->temperature,
        ], self::penaltyParams($model));

        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_POST           => true,
            CURLOPT_POSTFIELDS     => json_encode($payload),
            CURLOPT_HTTPHEADER     => [
                'Content-Type: application/json',
                'Authorization: Bearer ' . $model->api_key,
            ],
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => 120,
            CURLOPT_CONNECTTIMEOUT => 15,
            CURLOPT_SSL_VERIFYPEER => false,
        ]);

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

        if ($httpCode !== 200) {
            $detail = self::parseErrorBody($response) ?: ('HTTP ' . $httpCode);
            throw new HttpResponseException(json([
                'code'    => 1,
                'message' => 'AI 请求失败: ' . $detail,
                'data'    => null,
            ], 502));
        }

        $data = json_decode($response, true);
        if (!$data) {
            throw new HttpResponseException(json([
                'code'    => 1,
                'message' => 'AI 响应解析失败',
                'data'    => null,
            ], 502));
        }

        return $data;
    }

    /**
     * 测试模型连接是否正常
     * @return array{success: bool, latency_ms: int, reply: string, model: string}
     */
    public static function testConnection(array $config): array
    {
        $apiBaseUrl = rtrim($config['api_base_url'] ?? '', '/');
        $modelId = trim($config['model_id'] ?? '');
        $apiKey = $config['api_key'] ?? '';

        if (!$apiBaseUrl || !$modelId) {
            throw new \InvalidArgumentException('请填写 API 地址和 Model ID');
        }

        $url = $apiBaseUrl . '/chat/completions';
        $payload = [
            'model'       => $modelId,
            'messages'    => [
                ['role' => 'user', 'content' => '请只回复：测试成功'],
            ],
            'stream'      => false,
            'max_tokens'  => 32,
            'temperature' => (float) ($config['temperature'] ?? 0.7),
        ];

        $headers = ['Content-Type: application/json'];
        if ($apiKey !== '') {
            $headers[] = 'Authorization: Bearer ' . $apiKey;
        }

        $start = microtime(true);
        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_POST           => true,
            CURLOPT_POSTFIELDS     => json_encode($payload),
            CURLOPT_HTTPHEADER     => $headers,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => 30,
            CURLOPT_CONNECTTIMEOUT => 10,
            CURLOPT_SSL_VERIFYPEER => false,
        ]);

        $response = curl_exec($ch);
        $httpCode = (int) curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $curlError = curl_error($ch);
        curl_close($ch);

        $latencyMs = (int) round((microtime(true) - $start) * 1000);

        if ($response === false) {
            throw new \RuntimeException('连接失败: ' . ($curlError ?: '网络不可达'));
        }

        if ($httpCode !== 200) {
            $detail = self::parseErrorBody($response) ?: ('HTTP ' . $httpCode);
            throw new \RuntimeException('API 返回错误: ' . $detail);
        }

        $data = json_decode($response, true);
        if (!$data) {
            throw new \RuntimeException('响应解析失败，请确认接口为 OpenAI 兼容格式');
        }

        $reply = self::extractMessageContent($data);
        if ($reply === '') {
            throw new \RuntimeException('接口连接成功，但未返回有效内容');
        }

        return [
            'success'    => true,
            'latency_ms' => $latencyMs,
            'reply'      => $reply,
            'model'      => $modelId,
            'tokens'     => $data['usage']['total_tokens'] ?? null,
        ];
    }

    public static function extractStreamDelta(array $chunk): string
    {
        $choice = $chunk['choices'][0] ?? [];
        $delta = $choice['delta'] ?? [];
        $message = $choice['message'] ?? [];

        $content = $delta['content']
            ?? $delta['reasoning_content']
            ?? $message['content']
            ?? '';

        return is_string($content) ? $content : '';
    }

    public static function extractMessageContent(array $result): string
    {
        $choice = $result['choices'][0] ?? [];
        $message = $choice['message'] ?? [];

        $content = $message['content']
            ?? $message['reasoning_content']
            ?? $choice['text']
            ?? '';

        return is_string($content) ? trim($content) : '';
    }

    public static function sseHeaders(): void
    {
        header('Content-Type: text/event-stream; charset=utf-8');
        header('Cache-Control: no-cache, no-transform');
        header('Connection: keep-alive');
        header('X-Accel-Buffering: no');
    }

    public static function sseEvent(string $event, mixed $data): void
    {
        // 用户关闭页面后仍继续后台等待，不再往已断开的连接写数据
        if (connection_aborted()) {
            return;
        }

        echo "event: {$event}\n";
        echo 'data: ' . json_encode($data, JSON_UNESCAPED_UNICODE) . "\n\n";
        if (ob_get_level() > 0) {
            @ob_flush();
        }
        @flush();
    }

    private static function parseErrorBody(?string $body): ?string
    {
        if (!$body) {
            return null;
        }
        $json = json_decode($body, true);
        if (json_last_error() === JSON_ERROR_NONE) {
            return $json['error']['message'] ?? $json['message'] ?? null;
        }
        return trim($body) ?: null;
    }
}