<?php

declare(strict_types=1);

namespace app\common\service;

/**
 * Screenshot-only Dify transport. Reuses the configured assistant app, but never
 * enters clinical augmentation, OCR, history or protocol fallback. A rejected
 * answer may be regenerated once from the same image within the total deadline.
 * The private PHP upload is sent directly to Dify; no public storage is involved.
 */
final class DifyTongueScreenshotService
{
    private const MAX_RESPONSE_BYTES = 65536;
    private const TIMEOUT_SECONDS = 50;
    private const MIN_CORRECTION_SECONDS = 3;
    private const CORRECTION_PROMPT = <<<'PROMPT'
本次是唯一一次格式纠正。请重新检查本次同一张原图，严格按上述 JSON 契约重新输出完整结果，不得编造图片特征、症状、脉象或既往史。
limitations 只写光线、清晰度、遮挡等成像限制；缺少问诊、症状、脉诊等临床资料应写入 tcm_diagnosis.missing_information，不要混入舌象观察区。
候选名称及 summary 不得包含正常、健康、无异常等结论，不得确定诊断或给出治疗、药物、剂量。没有足够证型依据时返回 insufficient 和空 candidates，但保留原图中实际可见的 features，不得为了通过校验清空可见观察或编造依据。
仅输出符合完整契约的一个 JSON 对象，不要解释、Markdown 或额外字段。
PROMPT;

    public static function analyze(TongueScreenshotImage $image, string $model = 'qwen'): array
    {
        $config = config('prescription_ai') ?: [];
        $settings = self::settings($config, $model);
        if (!function_exists('curl_init')) throw new \DomainException('截图分析服务暂不可用');
        $deadline = microtime(true) + self::TIMEOUT_SECONDS;
        // No patient, diagnosis, admin ID, filename or historical conversation is sent.
        $user = 'tongue-screenshot-' . bin2hex(random_bytes(16));
        $upload = self::post($settings['base'] . '/files/upload', $settings, [
            'user' => $user,
            'file' => new \CURLFile($image->path(), 'image/jpeg', 'video-screenshot.jpg'),
        ], $deadline);
        if (!is_string($upload['id'] ?? null)
            || !preg_match('/\A[a-zA-Z0-9_-]{1,128}\z/D', $upload['id'])) {
            throw new \DomainException('截图上传分析服务失败，请稍后重试');
        }
        // An upload failure can never become a text-only success. Both possible
        // model calls use this same private image and anonymous request-local user.
        $payload = [
            'inputs' => (object) [],
            'query' => TongueScreenshotAnalysis::prompt(),
            'response_mode' => 'blocking',
            'user' => $user,
            'auto_generate_name' => false,
            'files' => [['type' => 'image', 'transfer_method' => 'local_file', 'upload_file_id' => $upload['id']]],
        ];
        $response = self::post($settings['base'] . '/chat-messages', $settings,
            json_encode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_THROW_ON_ERROR), $deadline);
        $answer = self::answer($response);
        try {
            $analysis = TongueScreenshotAnalysis::parse($answer);
        } catch (\DomainException $error) {
            if ($deadline - microtime(true) < self::MIN_CORRECTION_SECONDS) throw $error;
            // Only parser rejection permits one correction. Never replay the
            // rejected answer, reset the budget, upload again or change models.
            $payload['query'] = TongueScreenshotAnalysis::prompt() . "\n" . self::CORRECTION_PROMPT;
            $response = self::post($settings['base'] . '/chat-messages', $settings,
                json_encode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_THROW_ON_ERROR), $deadline);
            $analysis = TongueScreenshotAnalysis::parse(self::answer($response));
        }
        return ['analysis' => $analysis, 'model' => $model, 'model_label' => $settings['label']];
    }

    private static function answer(array $response): string
    {
        if (!is_string($response['answer'] ?? null) || strlen($response['answer']) > 32768) {
            throw new \DomainException('截图分析未返回有效结果，请重新截图后重试');
        }
        return $response['answer'];
    }

    private static function settings(array $config, string $model): array
    {
        if (!in_array($model, ['qwen', 'openai'], true)) throw new \DomainException('截图分析模型无效');
        if (empty($config['enable'])) throw new \DomainException('AI 截图分析功能未启用');
        // The selected profile owns both the image upload and chat. No cross-model fallback.
        $profile = $config['models'][$model] ?? [];
        $base = rtrim(trim((string) ($config['base_url'] ?? '')), '/');
        $key = trim((string) ($profile['api_key'] ?? ''));
        $parts = parse_url($base);
        if (!is_array($parts) || !in_array(strtolower($parts['scheme'] ?? ''), ['https', 'http'], true)
            || empty($parts['host']) || isset($parts['user']) || isset($parts['pass'])
            || isset($parts['query']) || isset($parts['fragment'])
            || preg_match('/[\x00-\x20\x7f]/', $base) || $key === ''
            || preg_match('/[\x00-\x1f\x7f]/', (string) ($profile['api_key'] ?? ''))
            || str_ends_with(strtolower($parts['path'] ?? ''), '/chat/completions')) {
            throw new \DomainException('截图分析服务配置不完整');
        }
        if (str_ends_with($base, '/chat-messages')) $base = substr($base, 0, -strlen('/chat-messages'));
        elseif (!str_ends_with($base, '/v1')) $base .= '/v1';
        $caFile = (string) ($config['required_attachment_upload']['ca_file'] ?? '');
        if ($caFile !== '' && (!is_file($caFile) || !is_readable($caFile))) {
            // Match the established attachment transport on other hosts: an
            // optional stale CA path falls back to the system trust store.
            // CURLOPT_SSL_VERIFYPEER/VERIFYHOST remain enabled below.
            $caFile = '';
        }
        $label = $model === 'qwen' ? '千问' : 'GPT';
        return ['base' => $base, 'key' => $key, 'ca_file' => $caFile, 'label' => $label];
    }

    /** Exactly one bounded POST; redirects and ambient proxies must not receive credentials/images. */
    private static function post(string $url, array $settings, $payload, float $deadline): array
    {
        $milliseconds = (int) floor(($deadline - microtime(true)) * 1000);
        if ($milliseconds < 1) throw new \DomainException('截图分析超时，请稍后重试');
        $curl = curl_init();
        if ($curl === false) throw new \DomainException('截图分析服务暂不可用');
        $body = ''; $tooLarge = false;
        try {
            $headers = ['Authorization: Bearer ' . $settings['key'], 'Accept: application/json', 'Expect:'];
            if (is_string($payload)) $headers[] = 'Content-Type: application/json';
            $options = [
                CURLOPT_URL => $url, CURLOPT_POST => true, CURLOPT_POSTFIELDS => $payload,
                CURLOPT_HTTPHEADER => $headers, CURLOPT_RETURNTRANSFER => false,
                CURLOPT_FOLLOWLOCATION => false, CURLOPT_MAXREDIRS => 0, CURLOPT_PROXY => '',
                CURLOPT_PROTOCOLS => CURLPROTO_HTTP | CURLPROTO_HTTPS,
                CURLOPT_SSL_VERIFYPEER => true, CURLOPT_SSL_VERIFYHOST => 2,
                CURLOPT_TIMEOUT_MS => $milliseconds, CURLOPT_CONNECTTIMEOUT_MS => min(8000, $milliseconds),
                CURLOPT_NOSIGNAL => true,
                CURLOPT_WRITEFUNCTION => static function ($handle, string $chunk) use (&$body, &$tooLarge): int {
                    if (strlen($body) + strlen($chunk) > self::MAX_RESPONSE_BYTES) { $tooLarge = true; return 0; }
                    $body .= $chunk;
                    return strlen($chunk);
                },
            ];
            if ($settings['ca_file'] !== '') $options[CURLOPT_CAINFO] = $settings['ca_file'];
            if (!curl_setopt_array($curl, $options)) throw new \DomainException('截图分析服务暂不可用');
            $ok = curl_exec($curl);
            $status = (int) curl_getinfo($curl, CURLINFO_HTTP_CODE);
            if (curl_errno($curl) === CURLE_OPERATION_TIMEDOUT) throw new \DomainException('截图分析超时，请稍后重试');
            if ($ok === false || $tooLarge || $status < 200 || $status >= 300) {
                // Deliberately discard upstream bodies/errors; they can contain image/model data or secrets.
                if ($ok !== false && !$tooLarge && $status === 400) {
                    $failure = json_decode($body, true);
                    if (is_array($failure) && ($failure['code'] ?? '') === 'invalid_param'
                        && is_string($failure['message'] ?? null)
                        && preg_match('/\[models\].{0,200}(?:status code 404|404 page not found)/is', $failure['message'])) {
                        throw new \DomainException($settings['label'] . ' 模型接口配置异常，请管理员检查 Dify 中的模型 API 地址。');
                    }
                }
                throw new \DomainException('截图分析服务暂不可用，请稍后重试');
            }
            try { $decoded = json_decode($body, true, 24, JSON_THROW_ON_ERROR); }
            catch (\Throwable $error) { throw new \DomainException('截图分析服务返回格式无效'); }
            if (!is_array($decoded)) throw new \DomainException('截图分析服务返回格式无效');
            return $decoded;
        } finally {
            curl_close($curl);
        }
    }
}