import { mkdir, readFile, writeFile } from 'node:fs/promises';
import { homedir } from 'node:os';
import { dirname, join } from 'node:path';
import type { OkraPiConfig } from './types.js';

export function configPath(): string {
  if (process.env.PDF_PARSE_CONFIG) return process.env.PDF_PARSE_CONFIG;
  if (process.env.OKRA_PI_CONFIG) return process.env.OKRA_PI_CONFIG;
  const agentDir = process.env.PI_CODING_AGENT_DIR ?? join(homedir(), '.pi', 'agent');
  return join(agentDir, 'pdf-parse.json');
}

export async function readConfig(path = configPath()): Promise<OkraPiConfig> {
  try {
    const parsed: unknown = JSON.parse(await readFile(path, 'utf8'));
    if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
      return { aliases: {} };
    }
    const record = parsed as Record<string, unknown>;
    const aliases: Record<string, string> = {};
    if (record.aliases && typeof record.aliases === 'object' && !Array.isArray(record.aliases)) {
      for (const [name, value] of Object.entries(record.aliases as Record<string, unknown>)) {
        if (typeof value === 'string') aliases[name] = value;
      }
    }
    return {
      ...(typeof record.defaultModel === 'string' ? { defaultModel: record.defaultModel } : {}),
      aliases,
    };
  } catch (error) {
    if ((error as NodeJS.ErrnoException).code === 'ENOENT') {
      if (path === configPath() && !process.env.PDF_PARSE_CONFIG && !process.env.OKRA_PI_CONFIG) {
        const legacyPath = join(dirname(path), 'okra.json');
        if (legacyPath !== path) {
          try {
            return await readConfig(legacyPath);
          } catch (legacyError) {
            if ((legacyError as NodeJS.ErrnoException).code !== 'ENOENT') throw legacyError;
          }
        }
      }
      return { aliases: {} };
    }
    throw error;
  }
}

export async function writeConfig(config: OkraPiConfig, path = configPath()): Promise<void> {
  await mkdir(dirname(path), { recursive: true, mode: 0o700 });
  await writeFile(path, `${JSON.stringify(config, null, 2)}\n`, { mode: 0o600 });
}