/**
 * 配置读写：key 池、活跃 key、冷却、配额封禁。
 * 零 pi 依赖的纯业务模块，可被 pi / dsh 复用。
 */

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

export const DEFAULT_COOLDOWN_MINUTES = 60;
export const DEFAULT_WATCHDOG_IDLE_MS = 90_000;

export interface KeyEntry {
  name: string;
  key: string;
}

export interface Config {
  keys: KeyEntry[];
  activeKeyIndex: number;
  cooldownMinutes: number;
  watchdogEnabled: boolean;
  watchdogIdleMs: number;
  /** key 下标 → 冷却开始时刻（epoch ms） */
  cooldowns: Record<number, number>;
  /** key 下标 → 配额封禁解除时刻（epoch ms） */
  quotaBlockedUntil: Record<number, number>;
  /** sessionId → 已绑定的 key 下标 */
  sessionAffinity: Record<string, number>;
}

export const EMPTY_CONFIG: Config = {
  keys: [],
  activeKeyIndex: 0,
  cooldownMinutes: DEFAULT_COOLDOWN_MINUTES,
  watchdogEnabled: true,
  watchdogIdleMs: DEFAULT_WATCHDOG_IDLE_MS,
  cooldowns: {},
  quotaBlockedUntil: {},
  sessionAffinity: {},
};

/** 返回一个全新的（深拷贝嵌套对象）空配置，避免浅拷贝共享 mutate 全局常量。 */
export function createEmptyConfig(): Config {
  return {
    keys: [],
    activeKeyIndex: 0,
    cooldownMinutes: DEFAULT_COOLDOWN_MINUTES,
    watchdogEnabled: true,
    watchdogIdleMs: DEFAULT_WATCHDOG_IDLE_MS,
    cooldowns: {},
    quotaBlockedUntil: {},
    sessionAffinity: {},
  };
}

const ENV_CONFIG_PATH = "PI_OPENCODE_ROTATION_CONFIG";

export function defaultConfigPath(): string {
  return join(homedir(), ".pi", "agent", "opencode-keys.json");
}

export function getConfigPath(env = process.env): string {
  return env[ENV_CONFIG_PATH] ?? defaultConfigPath();
}

export interface ConfigIO {
  read(path: string): string | undefined;
  write(path: string, data: string): void;
  exists(path: string): boolean;
  mkdir(dir: string): void;
  chmod(path: string, mode: number): void;
  dirname(path: string): string;
}

const nodeIO: ConfigIO = {
  read: (p) => (existsSync(p) ? readFileSync(p, "utf-8") : undefined),
  write: (p, d) => writeFileSync(p, d, { mode: 0o600 }),
  exists: existsSync,
  mkdir: (d) => mkdirSync(d, { recursive: true }),
  chmod: chmodSync,
  dirname,
};

/** 纯净版：注入 IO 便于测试 */
export function loadConfigPath(path: string, io: ConfigIO = nodeIO): Config {
  const raw = io.read(path);
  if (raw === undefined) return createEmptyConfig();
  try {
    const parsed = JSON.parse(raw) as Partial<Config>;
    return {
      ...createEmptyConfig(),
      ...parsed,
      cooldowns: parsed.cooldowns ?? {},
      quotaBlockedUntil: parsed.quotaBlockedUntil ?? {},
      sessionAffinity: parsed.sessionAffinity ?? {},
    };
  } catch {
    return createEmptyConfig();
  }
}

export function loadConfig(io: ConfigIO = nodeIO): Config {
  return loadConfigPath(getConfigPath(), io);
}

export function saveConfig(config: Config, io: ConfigIO = nodeIO): void {
  const path = getConfigPath();
  io.mkdir(io.dirname(path));
  io.write(path, JSON.stringify(config, null, 2));
  try {
    io.chmod(path, 0o600);
  } catch {
    /* best-effort */
  }
}

export function getCooldownMs(config: Config): number {
  return (config.cooldownMinutes || DEFAULT_COOLDOWN_MINUTES) * 60_000;
}

export function getWatchdogIdleMs(config: Config): number {
  return config.watchdogIdleMs > 0 ? config.watchdogIdleMs : DEFAULT_WATCHDOG_IDLE_MS;
}