/**
 * Auto-detect project and user context
 * NO environment variables needed!
 */

import { readFile } from 'fs/promises';
import { execSync } from 'child_process';
import os from 'os';
import path from 'path';

export interface AutoDetectedContext {
  // Project
  projectId: string;
  projectName: string;
  projectVersion?: string;
  projectDescription?: string;

  // User
  userId: string;
  userName: string;

  // Git
  gitRepo?: string;
  gitBranch?: string;
  gitCommit?: string;

  // Environment
  hostname: string;
  platform: string;
  nodeVersion: string;
}

/**
 * Auto-detect all context from environment
 * Falls back gracefully if any detection fails
 */
export async function autoDetectContext(
  projectRoot: string = process.cwd()
): Promise<AutoDetectedContext> {

  // ============================================================================
  // 1. AUTO-DETECT PROJECT from package.json
  // ============================================================================

  let projectId = path.basename(projectRoot);
  let projectName = projectId;
  let projectVersion: string | undefined;
  let projectDescription: string | undefined;

  try {
    const packagePath = path.join(projectRoot, 'package.json');
    const packageJson = JSON.parse(await readFile(packagePath, 'utf8'));

    if (packageJson.name) {
      // Clean project ID (remove @scope/ if present)
      projectId = packageJson.name.replace(/^@[^/]+\//, '');
      projectName = packageJson.name;
    }

    projectVersion = packageJson.version;
    projectDescription = packageJson.description;
  } catch {
    // Fallback: use directory name
    console.warn('⚠️  No package.json found, using directory name as projectId');
  }

  // ============================================================================
  // 2. AUTO-DETECT USER from git config or OS
  // ============================================================================

  let userId = 'unknown-user';
  let userName = 'Unknown User';

  try {
    // Try git config first (most accurate for dev context)
    const gitEmail = execSync('git config user.email', {
      encoding: 'utf8',
      stdio: ['pipe', 'pipe', 'ignore'],
      cwd: projectRoot
    }).trim();

    const gitName = execSync('git config user.name', {
      encoding: 'utf8',
      stdio: ['pipe', 'pipe', 'ignore'],
      cwd: projectRoot
    }).trim();

    if (gitEmail) userId = gitEmail;
    if (gitName) userName = gitName;
  } catch {
    // Git not available, try OS user info
    try {
      const osUser = os.userInfo();
      userId = osUser.username;
      userName = osUser.username;
    } catch {
      // Ultimate fallback (shouldn't happen)
      console.warn('⚠️  Could not detect user, using unknown-user');
    }
  }

  // ============================================================================
  // 3. AUTO-DETECT GIT REPOSITORY INFO
  // ============================================================================

  let gitRepo: string | undefined;
  let gitBranch: string | undefined;
  let gitCommit: string | undefined;

  try {
    gitRepo = execSync('git remote get-url origin', {
      encoding: 'utf8',
      stdio: ['pipe', 'pipe', 'ignore'],
      cwd: projectRoot
    }).trim();
  } catch {
    // No git remote
  }

  try {
    gitBranch = execSync('git branch --show-current', {
      encoding: 'utf8',
      stdio: ['pipe', 'pipe', 'ignore'],
      cwd: projectRoot
    }).trim();
  } catch {
    // Not in a git repo or detached HEAD
  }

  try {
    gitCommit = execSync('git rev-parse --short HEAD', {
      encoding: 'utf8',
      stdio: ['pipe', 'pipe', 'ignore'],
      cwd: projectRoot
    }).trim();
  } catch {
    // No git
  }

  // ============================================================================
  // 4. AUTO-DETECT ENVIRONMENT INFO
  // ============================================================================

  const hostname = os.hostname();
  const platform = `${os.platform()}-${os.arch()}`;
  const nodeVersion = process.version;

  return {
    projectId,
    projectName,
    projectVersion,
    projectDescription,
    userId,
    userName,
    gitRepo,
    gitBranch,
    gitCommit,
    hostname,
    platform,
    nodeVersion
  };
}

/**
 * Cached context (detect once, reuse)
 */
let cachedContext: AutoDetectedContext | null = null;

export async function getOrDetectContext(
  projectRoot?: string
): Promise<AutoDetectedContext> {
  if (!cachedContext || projectRoot) {
    cachedContext = await autoDetectContext(projectRoot);
  }
  return cachedContext;
}

/**
 * Clear cache (useful for testing)
 */
export function clearContextCache(): void {
  cachedContext = null;
}