"use strict";

import { existsSync, readFileSync } from "node:fs";
import { join } from "node:path";
import { homedir } from "node:os";

/** 平台端点映射 */
const PROVIDER_BASE_URLS: Record<string, string> = {
  // 智谱（bigmodel.cn）
  ZHIPU: "https://open.bigmodel.cn/api/paas/v4/",
  ZHIPU_CODING: "https://open.bigmodel.cn/api/coding/paas/v4/",
  // Z.AI
  ZAI: "https://api.z.ai/api/paas/v4/",
  ZAI_CODING: "https://api.z.ai/api/coding/paas/v4/",
};

/** 配置文件路径：~/.pi/agent/pi-zai-vision.json */
const CONFIG_FILE = join(homedir(), ".pi", "agent", "pi-zai-vision.json");

export interface VisionConfig {
  apiKey: string;
  baseUrl: string;
  mode: string;
  model: string;
  thinking: boolean;
  temperature: number;
  topP: number;
  maxTokens: number;
  timeoutSecs: number;
  maxImageSizeMB: number;
  maxVideoSizeMB: number;
}

interface ConfigFileContent {
  apiKey?: string;
  mode?: string;
  model?: string;
  thinking?: boolean;
  temperature?: number;
  topP?: number;
  maxTokens?: number;
  timeoutSecs?: number;
  maxImageSizeMB?: number;
  maxVideoSizeMB?: number;
}

/** 读取 ~/.pi/agent/pi-zai-vision.json（如果存在） */
function readConfigFile(): ConfigFileContent | null {
  try {
    if (!existsSync(CONFIG_FILE)) return null;
    const raw = readFileSync(CONFIG_FILE, "utf-8");
    return JSON.parse(raw) as ConfigFileContent;
  } catch {
    return null;
  }
}

/** 优先级：环境变量 > 配置文件 > 默认值 */
function resolve(key: string, envKey: string, fileVal: unknown, defaultVal: string): string;
function resolve(key: string, envKey: string, fileVal: unknown, defaultVal: number): number;
function resolve(key: string, envKey: string, fileVal: unknown, defaultVal: boolean): boolean;
function resolve(
  _key: string,
  envKey: string,
  fileVal: unknown,
  defaultVal: string | number | boolean
): string | number | boolean {
  // 1. 环境变量最高优先级
  const envVal = process.env[envKey];
  if (envVal !== undefined && envVal !== "") {
    if (typeof defaultVal === "number") return Number(envVal);
    if (typeof defaultVal === "boolean") return envVal !== "false" && envVal !== "0";
    return envVal;
  }
  // 2. 配置文件
  if (fileVal !== undefined && fileVal !== null) return fileVal as any;
  // 3. 默认值
  return defaultVal;
}

/**
 * 加载配置。
 * 优先级：环境变量 > ~/.pi/agent/pi-zai-vision.json > 默认值。
 * Z_AI_API_KEY 至少需要在环境变量或配置文件中设置一处。
 */
export function loadConfig(): VisionConfig {
  const file = readConfigFile();

  const apiKey = resolve("apiKey", "Z_AI_API_KEY", file?.apiKey, "");
  if (!apiKey) {
    throw new Error(
      "Z_AI_API_KEY is required. Set it via environment variable or in ~/.pi/agent/pi-zai-vision.json:\n" +
      '  {"apiKey": "your-api-key", "mode": "ZAI"}'
    );
  }

  const mode = (resolve("mode", "Z_AI_MODE", file?.mode, "ZAI") as string).toUpperCase();
  const baseUrl = PROVIDER_BASE_URLS[mode];
  if (!baseUrl) {
    throw new Error(
      `Unknown mode: "${mode}". Valid values: ZHIPU, ZHIPU_CODING, ZAI, ZAI_CODING.`
    );
  }

  return {
    apiKey: apiKey as string,
    baseUrl,
    mode,
    model: resolve("model", "Z_AI_MODEL", file?.model, "glm-4.6v") as string,
    thinking: resolve("thinking", "Z_AI_THINKING", file?.thinking, true) as boolean,
    temperature: resolve("temperature", "Z_AI_TEMPERATURE", file?.temperature, 0.8) as number,
    topP: resolve("topP", "Z_AI_TOP_P", file?.topP, 0.6) as number,
    maxTokens: resolve("maxTokens", "Z_AI_MAX_TOKENS", file?.maxTokens, 32768) as number,
    timeoutSecs: resolve("timeoutSecs", "Z_AI_TIMEOUT", file?.timeoutSecs, 300) as number,
    maxImageSizeMB: resolve("maxImageSizeMB", "Z_AI_MAX_IMAGE_SIZE_MB", file?.maxImageSizeMB, 5) as number,
    maxVideoSizeMB: resolve("maxVideoSizeMB", "Z_AI_MAX_VIDEO_SIZE_MB", file?.maxVideoSizeMB, 8) as number,
  };
}

let _config: VisionConfig | null = null;

/** 获取缓存的配置（懒加载） */
export function getConfig(): VisionConfig {
  if (!_config) {
    _config = loadConfig();
  }
  return _config;
}

/** 重置缓存（用于测试或重新加载配置） */
export function resetConfig(): void {
  _config = null;
}

/** 返回配置文件路径，方便用户知晓位置 */
export function getConfigFilePath(): string {
  return CONFIG_FILE;
}