import path from 'path';
import os from 'os';
import fs from 'fs';
import crypto from 'crypto';

export interface Config {
  port: number;
  defaultWorkDir: string;
  sessionDir: string;
  model: string;
  logLevel: string;
  apiKey: string;
  provider: string;
}

export interface AgentConfig {
  name: string;
  slug: string;
  prompt: string;
  /** REST API base URL (e.g. https://dev.team.uix.su/agent-api) */
  trackerUrl: string;
  /** WebSocket URL (e.g. wss://dev.team.uix.su/agent-ws). Falls back to trackerUrl with http→ws conversion. */
  wsUrl: string;
  token: string;
  transport: 'http' | 'ws';
  listenPort: number;
  workDir: string;
  agentHome: string;
  capabilities: string[];
  maxConcurrentTasks: number;
  model: string;
  provider: string;
  apiKey: string;
  heartbeatIntervalSec: number;
  /** Restrict file access to these directories. Empty = unrestricted. */
  allowedPaths: string[];
  /** Persistent session UUID — survives renames. Stored in agent.json. */
  sessionId: string;
}

const homeDir = os.homedir();

export function loadConfig(): Config {
  return {
    port: parseInt(process.env.PICOGENT_PORT || '3100', 10),
    defaultWorkDir: process.env.PICOGENT_WORK_DIR || process.cwd(),
    sessionDir: process.env.PICOGENT_SESSION_DIR || path.join(homeDir, '.picogent', 'sessions'),
    model: process.env.PICOGENT_MODEL || 'sonnet',
    logLevel: process.env.LOG_LEVEL || 'info',
    apiKey: process.env.PICOGENT_API_KEY || process.env.ANTHROPIC_API_KEY || '',
    provider: process.env.PICOGENT_PROVIDER || 'anthropic',
  };
}

interface ResolvedConfig {
  configPath: string | null;
  agentHome: string | null;
}

/**
 * Resolve config: CLI arg can be a .json file OR a directory.
 *
 * Directory mode: picogent ./agents/coder/
 *   → configPath = ./agents/coder/agent.json
 *   → agentHome  = ./agents/coder/
 *
 * File mode: picogent ./agent.json
 *   → configPath = ./agent.json
 *   → agentHome  = null
 *
 * Env/default fallback: same as before
 */
export function resolveConfig(): ResolvedConfig {
  const arg = process.argv[2];

  if (arg) {
    const resolved = path.resolve(arg);

    // Directory mode: picogent ./agents/coder/
    if (fs.existsSync(resolved) && fs.statSync(resolved).isDirectory()) {
      const configInDir = path.join(resolved, 'agent.json');
      return {
        configPath: fs.existsSync(configInDir) ? configInDir : null,
        agentHome: resolved,
      };
    }

    // File mode: picogent ./agent.json
    if (arg.endsWith('.json')) {
      return { configPath: resolved, agentHome: null };
    }
  }

  // Env fallback
  if (process.env.PICOGENT_CONFIG) {
    return { configPath: path.resolve(process.env.PICOGENT_CONFIG), agentHome: null };
  }

  // Default: ./agent.json if exists
  const defaultPath = path.resolve('./agent.json');
  if (fs.existsSync(defaultPath)) {
    return { configPath: defaultPath, agentHome: null };
  }

  return { configPath: null, agentHome: null };
}

/**
 * Agent mode if: config found, directory passed, or TRACKER_URL env set.
 */
export function hasAgentConfig(): boolean {
  const { configPath, agentHome } = resolveConfig();
  return configPath !== null || agentHome !== null || !!process.env.TRACKER_URL;
}

export function loadAgentConfig(): AgentConfig {
  const { configPath, agentHome } = resolveConfig();

  // Load file if available, otherwise empty object
  let file: Record<string, unknown> = {};
  if (configPath) {
    if (!fs.existsSync(configPath)) {
      throw new Error(`Agent config not found: ${configPath}`);
    }
    file = JSON.parse(fs.readFileSync(configPath, 'utf-8'));
  }

  const trackerUrl = process.env.TRACKER_URL || (file.tracker_url as string) || '';
  const token = process.env.AGENT_TOKEN || (file.token as string) || '';

  if (!trackerUrl) {
    throw new Error('Tracker URL required. Set TRACKER_URL env or tracker_url in config.');
  }
  if (!token) {
    throw new Error('Agent token required. Set AGENT_TOKEN env or token in config.');
  }

  // In directory mode, agentHome IS the work dir (unless overridden)
  const resolvedHome = agentHome || '';
  const workDir = process.env.PICOGENT_WORK_DIR
    || (file.work_dir as string)
    || resolvedHome
    || process.cwd();

  const wsUrl = process.env.AGENT_WS_URL || (file.ws_url as string) || '';

  return {
    name: (file.name as string) || process.env.AGENT_NAME || 'Agent',
    slug: (file.slug as string) || process.env.AGENT_SLUG || 'agent',
    prompt: (file.prompt as string) || process.env.AGENT_PROMPT || '',
    trackerUrl,
    wsUrl,
    token,
    transport: (process.env.AGENT_TRANSPORT || (file.transport as string) || 'http') as 'http' | 'ws',
    listenPort: parseInt(process.env.AGENT_PORT || String(file.listen_port || '3200'), 10),
    workDir,
    agentHome: resolvedHome || workDir,
    capabilities: (file.capabilities as string[]) || ['coding'],
    maxConcurrentTasks: (file.max_concurrent_tasks as number) || 2,
    model: process.env.PICOGENT_MODEL || (file.model as string) || 'sonnet',
    provider: process.env.PICOGENT_PROVIDER || (file.provider as string) || 'anthropic',
    apiKey: process.env.PICOGENT_API_KEY || process.env.ANTHROPIC_API_KEY || (file.api_key as string) || '',
    heartbeatIntervalSec: (file.heartbeat_interval_sec as number) || 30,
    allowedPaths: (file.allowed_paths as string[]) || [],
    sessionId: ensureSessionId(file, configPath),
  };
}

/**
 * Ensure agent.json has a persistent session_id.
 * Generates UUID on first run and writes it back to the config file.
 */
function ensureSessionId(file: Record<string, unknown>, configPath: string | null): string {
  if (file.session_id && typeof file.session_id === 'string') {
    return file.session_id;
  }

  const id = crypto.randomUUID();

  // Persist to agent.json if we have a path
  if (configPath) {
    try {
      file.session_id = id;
      fs.writeFileSync(configPath, JSON.stringify(file, null, 2) + '\n');
    } catch {
      // Non-fatal — session works in memory
    }
  }

  return id;
}