<?php

namespace app\common\service;

/**
 * OpenAI 兼容 Chat Completions 客户端
 */
class AiChatService
{
    public static function isEnabled(): bool
    {
        $cfg = config('ai') ?: [];
        return !empty($cfg['enable']) && trim((string) ($cfg['api_key'] ?? '')) !== '';
    }

    /**
     * @param array<int, array{role:string,content:string}> $messages
     * @param array<string, mixed> $options
     * @return array{ok:bool,content?:string,error?:string,raw?:array}
     */
    public static function chat(array $messages, array $options = []): array
    {
        $cfg = config('ai') ?: [];
        if (empty($cfg['enable'])) {
            return ['ok' => false, 'error' => 'AI 未启用'];
        }
        $apiKey = trim((string) ($cfg['api_key'] ?? ''));
        if ($apiKey === '') {
            return ['ok' => false, 'error' => 'AI 密钥未配置'];
        }

        $baseUrl = rtrim((string) ($cfg['base_url'] ?? 'https://api.deepseek.com'), '/');
        $model   = (string) ($options['model'] ?? ($cfg['model'] ?? 'deepseek-chat'));
        $timeout = (int) ($options['timeout'] ?? ($cfg['timeout'] ?? 60));

        $payload = [
            'model'       => $model,
            'messages'    => $messages,
            'temperature' => (float) ($options['temperature'] ?? 0.4),
            'max_tokens'  => (int) ($options['max_tokens'] ?? 1200),
        ];
        if (!empty($options['response_format'])) {
            $payload['response_format'] = $options['response_format'];
        }

        $url = $baseUrl . '/v1/chat/completions';
        $ch  = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload, JSON_UNESCAPED_UNICODE));
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, min(8, max(3, (int) ceil($timeout / 3))));
        curl_setopt($ch, CURLOPT_TIMEOUT, max(5, $timeout));
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
        curl_setopt($ch, CURLOPT_HTTPHEADER, [
            'Content-Type: application/json',
            'Authorization: Bearer ' . $apiKey,
        ]);

        $body  = curl_exec($ch);
        $errno = curl_errno($ch);
        $err   = curl_error($ch);
        $code  = (int) curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($errno) {
            return ['ok' => false, 'error' => 'AI 请求失败：' . $err];
        }

        $decoded = json_decode((string) $body, true);
        if ($code >= 400 || !is_array($decoded)) {
            $msg = is_array($decoded) ? ($decoded['error']['message'] ?? $decoded['message'] ?? 'AI 返回异常') : 'AI 返回异常';
            return ['ok' => false, 'error' => (string) $msg, 'raw' => $decoded];
        }

        $content = (string) ($decoded['choices'][0]['message']['content'] ?? '');
        if ($content === '') {
            return ['ok' => false, 'error' => 'AI 未返回内容', 'raw' => $decoded];
        }

        return ['ok' => true, 'content' => $content, 'raw' => $decoded];
    }

    /**
     * 流式 Chat Completions（OpenAI SSE 格式）
     *
     * @param callable(string):void $onDelta 每收到一段文本回调
     * @return array{ok:bool,content?:string,error?:string}
     */
    public static function streamChat(array $messages, callable $onDelta, array $options = []): array
    {
        $cfg = config('ai') ?: [];
        if (empty($cfg['enable'])) {
            return ['ok' => false, 'error' => 'AI 未启用'];
        }
        $apiKey = trim((string) ($cfg['api_key'] ?? ''));
        if ($apiKey === '') {
            return ['ok' => false, 'error' => 'AI 密钥未配置'];
        }

        $baseUrl = rtrim((string) ($cfg['base_url'] ?? 'https://api.deepseek.com'), '/');
        $model   = (string) ($options['model'] ?? ($cfg['model'] ?? 'deepseek-chat'));
        $timeout = (int) ($options['timeout'] ?? ($cfg['timeout'] ?? 60));

        $payload = [
            'model'       => $model,
            'messages'    => $messages,
            'temperature' => (float) ($options['temperature'] ?? 0.4),
            'max_tokens'  => (int) ($options['max_tokens'] ?? 1200),
            'stream'      => true,
        ];

        $lineBuffer  = '';
        $fullContent = '';

        $writeFn = static function ($ch, string $chunk) use (&$lineBuffer, &$fullContent, $onDelta): int {
            $lineBuffer .= $chunk;
            while (($pos = strpos($lineBuffer, "\n")) !== false) {
                $line       = rtrim(substr($lineBuffer, 0, $pos), "\r");
                $lineBuffer = substr($lineBuffer, $pos + 1);
                if ($line === '' || strncmp($line, 'data:', 5) !== 0) {
                    continue;
                }
                $data = trim(substr($line, 5));
                if ($data === '' || $data === '[DONE]') {
                    continue;
                }
                $json = json_decode($data, true);
                if (!is_array($json)) {
                    continue;
                }
                $delta = (string) ($json['choices'][0]['delta']['content'] ?? '');
                if ($delta === '') {
                    continue;
                }
                $fullContent .= $delta;
                $onDelta($delta);
            }

            return strlen($chunk);
        };

        $url = $baseUrl . '/v1/chat/completions';
        $ch  = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload, JSON_UNESCAPED_UNICODE));
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, false);
        curl_setopt($ch, CURLOPT_WRITEFUNCTION, $writeFn);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, min(8, max(3, (int) ceil($timeout / 3))));
        curl_setopt($ch, CURLOPT_TIMEOUT, max(10, $timeout));
        curl_setopt($ch, CURLOPT_TCP_NODELAY, true);
        curl_setopt($ch, CURLOPT_BUFFERSIZE, 128);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
        curl_setopt($ch, CURLOPT_HTTPHEADER, [
            'Content-Type: application/json',
            'Authorization: Bearer ' . $apiKey,
            'Accept: text/event-stream',
        ]);

        curl_exec($ch);
        $errno = curl_errno($ch);
        $err   = curl_error($ch);
        $code  = (int) curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($errno) {
            return ['ok' => false, 'error' => 'AI 请求失败：' . $err];
        }
        if ($code >= 400) {
            return ['ok' => false, 'error' => 'AI 返回异常（HTTP ' . $code . '）'];
        }
        if ($fullContent === '') {
            return ['ok' => false, 'error' => 'AI 未返回内容'];
        }

        return ['ok' => true, 'content' => $fullContent];
    }
}