import { getHostBridge } from "../engine/host-bridge";
import { RuntimeError } from "../engine/types";

export type ChatContentPart =
  | { type: "text"; text: string }
  | { type: "image_url"; image_url: { url: string } };

export interface ChatMessage {
  role: "system" | "user" | "assistant";
  content: string | ChatContentPart[];
}

export interface ResolvedAiConfig {
  baseUrl: string;
  apiKey: string;
  model: string;
  visionModel: string;
}

export function getAiConfig(): ResolvedAiConfig {
  const bridge = getHostBridge();
  // 宿主桥未注入（vitest / CLI 未配置）时返回空配置，requireAiConfig 统一抛 ai_not_configured
  const config = bridge ? bridge.loadAiConfig() : { baseUrl: "", apiKey: "", model: "", visionModel: "" };
  return { ...config, visionModel: config.visionModel || config.model };
}

export function requireAiConfig(options: { vision?: boolean } = {}): ResolvedAiConfig {
  const config = getAiConfig();
  if (!config.baseUrl || !config.model || (options.vision && !config.visionModel)) {
    throw new RuntimeError("ai_not_configured", "AI 服务未配置", {
      recommendation: options.vision
        ? "到 设置 → AI 服务 填写 Base URL 与多模态视觉模型（兼容 OpenAI 协议）"
        : "到 设置 → AI 服务 填写 Base URL 与模型名（兼容 OpenAI 协议）"
    });
  }
  return config;
}

export interface ChatCompletionOptions {
  temperature?: number;
  vision?: boolean;
  /** 交互式请求（用户正在等待，如 AI 拾取）：默认短超时 45s、最多 2 次，超时不重试 */
  interactive?: boolean;
  /** 单次请求超时毫秒数；显式指定后覆盖交互式/后台默认值 */
  timeoutMs?: number;
  /** 最大尝试次数；显式指定后覆盖交互式/后台默认值 */
  maxAttempts?: number;
}

export async function chatCompletion(messages: ChatMessage[], options: ChatCompletionOptions = {}): Promise<string> {
  const config = requireAiConfig({ vision: options.vision });
  const base = config.baseUrl.replace(/\/+$/, "");
  const interactive = options.interactive === true;
  const timeoutMs = Math.max(1000, Math.round(options.timeoutMs ?? (interactive ? 45000 : 170000)));
  const maxAttempts = Math.max(1, Math.round(options.maxAttempts ?? (interactive ? 2 : 3)));

  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
    let response: Response;
    try {
      response = await fetch(base + "/chat/completions", {
        signal: AbortSignal.timeout(timeoutMs),
        method: "POST",
        headers: { "Content-Type": "application/json", Authorization: "Bearer " + config.apiKey },
        body: JSON.stringify({
          model: options.vision ? config.visionModel : config.model,
          messages,
          temperature: options.temperature ?? 0.3
        })
      });
    } catch (error) {
      // 超时（AbortSignal.timeout）不重试：重发只会成倍拉长等待
      if ((error as { name?: string }).name === "TimeoutError") {
        throw new RuntimeError("ai_request_timeout", `AI 请求超时（${timeoutMs}ms），请检查网络或稍后重试`);
      }
      if (attempt === maxAttempts) throw error;
      await new Promise(resolve => setTimeout(resolve, 1200 * attempt));
      continue;
    }

    if (response.ok) {
      const data = (await response.json()) as { choices?: Array<{ message?: { content?: string } }> };
      return data.choices?.[0]?.message?.content ?? "";
    }

    const detail = (await response.text()).slice(0, 300);
    const retryable = response.status === 408 || response.status === 429 || response.status >= 500;
    if (retryable && attempt < maxAttempts) {
      const retryAfter = Number(response.headers.get("retry-after"));
      const fallbackDelay = 1400 * attempt;
      const delay = Number.isFinite(retryAfter) && retryAfter >= 0 && retryAfter <= 15
        ? retryAfter * 1000
        : fallbackDelay;
      await new Promise(resolve => setTimeout(resolve, delay));
      continue;
    }

    if (response.status === 429) {
      const suffix = detail ? " 详情：" + detail.slice(0, 180) : "";
      throw new RuntimeError("ai_rate_limited", "AI 服务限流或配额不足（HTTP 429），请稍后重试或更换可用视觉模型。" + suffix);
    }

    throw new RuntimeError("ai_request_failed", "AI 请求失败（HTTP " + response.status + "）：" + detail);
  }

  throw new RuntimeError("ai_request_failed", "AI 请求失败：已重试仍未成功");
}