import fs from 'node:fs';
import path from 'node:path';

export const MEMIND_RUNTIME_PROFILES = new Set(['local', 'split-service', 'production']);

/**
 * Load Memind env files in standard order. Later files only fill unset keys.
 */
export function loadMemindEnvFiles(rootDir, env = process.env) {
  const root = path.resolve(rootDir);
  for (const relativePath of ['../../.env.local', '.env']) {
    loadEnvFile(path.join(root, relativePath), env);
  }
}

function loadEnvFile(filePath, env = process.env) {
  if (!fs.existsSync(filePath)) return;
  for (const line of fs.readFileSync(filePath, 'utf8').split('\n')) {
    const trimmed = line.trim();
    if (!trimmed || trimmed.startsWith('#')) continue;
    const separator = trimmed.indexOf('=');
    if (separator < 0) continue;
    const key = trimmed.slice(0, separator).trim();
    const value = trimmed.slice(separator + 1).trim();
    if (!env[key]) env[key] = value;
  }
}

function expandEnvReference(value, env = process.env) {
  const raw = String(value ?? '').trim();
  const match = raw.match(/^\$\{([A-Z0-9_]+)\}$/);
  if (!match) return raw;
  return String(env[match[1]] ?? '').trim() || raw;
}

export function resolveMemindRuntimeProfile(env = process.env) {
  const explicit = String(env.MEMIND_RUNTIME_PROFILE ?? '').trim().toLowerCase();
  if (explicit) {
    if (!MEMIND_RUNTIME_PROFILES.has(explicit)) {
      throw new Error(
        `Unsupported MEMIND_RUNTIME_PROFILE "${explicit}". Expected: ${[...MEMIND_RUNTIME_PROFILES].join(', ')}`,
      );
    }
    return explicit;
  }
  if (String(env.NODE_ENV ?? '').trim().toLowerCase() === 'production') {
    return 'production';
  }
  return 'local';
}

/**
 * Apply environment-specific defaults after .env files are loaded.
 *
 * - local: monolith MindSpace adapter, repo-local storage (pnpm dev default)
 * - split-service: remote adapter against standalone MindSpace on 8082
 * - production: no overrides; 103 .env is source of truth
 */
export function applyMemindRuntimeProfile({
  rootDir = process.cwd(),
  env = process.env,
  profile,
} = {}) {
  const resolvedProfile = profile ?? resolveMemindRuntimeProfile(env);
  env.MEMIND_RUNTIME_PROFILE = resolvedProfile;

  if (resolvedProfile === 'local') {
    env.MINDSPACE_SERVER_ADAPTER = 'local';
    if (!env.MINDSPACE_STORAGE_ROOT) {
      env.MINDSPACE_STORAGE_ROOT = path.join(path.resolve(rootDir), 'data', 'mindspace');
    }
    return {
      profile: resolvedProfile,
      mindspaceAdapter: 'local',
      storageRoot: env.MINDSPACE_STORAGE_ROOT,
    };
  }

  if (resolvedProfile === 'split-service') {
    env.MINDSPACE_SERVER_ADAPTER = 'remote';
    env.MINDSPACE_REMOTE_BASE_URL = String(
      env.MINDSPACE_REMOTE_BASE_URL ?? 'http://127.0.0.1:8082',
    ).trim();
    const expandedToken = expandEnvReference(env.MINDSPACE_REMOTE_AUTH_TOKEN, env);
    if (expandedToken) {
      env.MINDSPACE_REMOTE_AUTH_TOKEN = expandedToken;
    } else if (env.TKMIND_SERVER__SECRET_KEY) {
      env.MINDSPACE_REMOTE_AUTH_TOKEN = String(env.TKMIND_SERVER__SECRET_KEY).trim();
    }
    if (!env.MINDSPACE_STORAGE_ROOT) {
      env.MINDSPACE_STORAGE_ROOT = '/Users/john/MindSpace/data/mindspace';
    }
    return {
      profile: resolvedProfile,
      mindspaceAdapter: 'remote',
      remoteBaseUrl: env.MINDSPACE_REMOTE_BASE_URL,
      storageRoot: env.MINDSPACE_STORAGE_ROOT,
    };
  }

  return {
    profile: resolvedProfile,
    mindspaceAdapter: String(env.MINDSPACE_SERVER_ADAPTER ?? 'local').trim().toLowerCase() || 'local',
    storageRoot: env.MINDSPACE_STORAGE_ROOT ?? null,
  };
}

export function describeMemindRuntimeProfile(env = process.env) {
  const profile = resolveMemindRuntimeProfile(env);
  const adapter = String(env.MINDSPACE_SERVER_ADAPTER ?? 'local').trim().toLowerCase() || 'local';
  const parts = [`MEMIND_RUNTIME_PROFILE=${profile}`, `MINDSPACE_SERVER_ADAPTER=${adapter}`];
  if (adapter === 'remote') {
    parts.push(`MINDSPACE_REMOTE_BASE_URL=${env.MINDSPACE_REMOTE_BASE_URL ?? '(unset)'}`);
  }
  if (env.MINDSPACE_STORAGE_ROOT) {
    parts.push(`MINDSPACE_STORAGE_ROOT=${env.MINDSPACE_STORAGE_ROOT}`);
  }
  return parts.join(', ');
}