import { existsSync } from 'node:fs';
import { mkdir, readFile, writeFile } from 'node:fs/promises';
import { homedir } from 'node:os';
import { dirname, resolve } from 'node:path';
import { randomBytes } from 'node:crypto';

export type CompanionConfig = {
  accessKey: string;
  workspaceRoot: string;
};

export function getConfigPath(): string {
  return process.env.HERMES_MOBILE_CONFIG ?? resolve(homedir(), '.config/hermes-mobile/companion.json');
}

export function getWorkspaceRoot(): string {
  return resolve(process.env.HERMES_MOBILE_WORKSPACE_ROOT ?? process.cwd());
}

export function generateAccessKey(): string {
  return `hm_${randomBytes(24).toString('base64url')}`;
}

export async function readCompanionConfig(): Promise<Partial<CompanionConfig>> {
  const configPath = getConfigPath();

  if (!existsSync(configPath)) {
    return {};
  }

  const rawConfig = await readFile(configPath, 'utf8');
  const parsedConfig = JSON.parse(rawConfig) as Partial<CompanionConfig>;

  return parsedConfig;
}

export async function writeCompanionConfig(config: CompanionConfig): Promise<void> {
  const configPath = getConfigPath();
  await mkdir(dirname(configPath), { recursive: true });
  await writeFile(configPath, `${JSON.stringify(config, null, 2)}\n`, { mode: 0o600 });
}

export async function ensureCompanionConfig(): Promise<CompanionConfig> {
  const existingConfig = await readCompanionConfig();
  const config: CompanionConfig = {
    accessKey: existingConfig.accessKey || process.env.HERMES_MOBILE_ACCESS_KEY || generateAccessKey(),
    workspaceRoot: resolve(existingConfig.workspaceRoot || getWorkspaceRoot()),
  };

  await writeCompanionConfig(config);
  return config;
}

export async function getRuntimeConfig(): Promise<CompanionConfig> {
  const existingConfig = await readCompanionConfig();

  return {
    accessKey: process.env.HERMES_MOBILE_ACCESS_KEY || existingConfig.accessKey || '',
    workspaceRoot: resolve(process.env.HERMES_MOBILE_WORKSPACE_ROOT || existingConfig.workspaceRoot || process.cwd()),
  };
}