import * as readline from 'node:readline';
import type { ManagedSession } from '../../session/index.js';
import type { ModelClient, TokenUsage } from '../../models/types.js';
import type { ModelRouter, ModelTier } from '../../models/router.js';
import type { NativeAgent } from '../../backends/native/agent.js';
import { parseCommand, getHelpText, resolveModelAlias, getCommandCompletions, getCommandTooltip, type Command } from './commands.js';
import { renderMarkdown } from './markdown.js';
import type { ModelConfig, ModelProvider } from '../../config/schema.js';
import { MODEL_PROVIDERS } from '../../config/schema.js';
import { OllamaClient, LlamaCppClient } from '../../models/index.js';
import { createClientFromConfig } from '../../daemon/index.js';
import {
  loadStoredAnthropicAuth,
  loadStoredAnthropicAuthToken,
  loadStoredOpenAIApiKey,
  loadStoredOpenAIAuth,
  loadStoredZaiAuth,
  loginGitHub,
  loginOpenAI,
  storeAnthropicAuth,
  storeAnthropicAuthToken,
  storeOpenAIApiKey,
  storeZaiAuth,
} from '../../auth/index.js';
import type { PairingManager } from '../../channels/pairing.js';
import { getColoredBanner } from './banner.js';
import type { HookEngine } from '../../hooks/index.js';

export { parseCommand, type Command };

// ANSI color codes
const colors = {
  reset: '\x1b[0m',
  bold: '\x1b[1m',
  dim: '\x1b[2m',
  blue: '\x1b[34m',
  orange: '\x1b[38;5;208m',
  gray: '\x1b[90m',
  bgDark: '\x1b[48;5;234m',
};

export function formatPrompt(state: 'default' | 'thinking'): string {
  if (state === 'thinking') {
    return `${colors.orange}flynn...${colors.reset} `;
  }
  return `${colors.orange}${colors.bold}flynn>${colors.reset} `;
}

export interface MinimalTuiConfig {
  session: ManagedSession;
  modelClient: ModelClient;
  modelRouter?: ModelRouter;
  systemPrompt: string;
  agent?: NativeAgent;
  onFullscreen?: () => void;
  onTransfer?: (target: string) => void;
  localProviders?: Record<string, ModelConfig>;
  modelProviderConfigs?: Partial<Record<ModelProvider, ModelConfig>>;
  currentLocalProvider?: string;
  pairingManager?: PairingManager;
  hookEngine?: HookEngine;
}

export class MinimalTui {
  private rl: readline.Interface | null = null;
  private running = false;
  private totalUsage: TokenUsage = { inputTokens: 0, outputTokens: 0 };
  private currentHint = '';
  private lastLine = '';

  constructor(private config: MinimalTuiConfig) {}

  private showHint(line: string): void {
    if (!line.startsWith('/')) {
      this.clearHint();
      return;
    }

    const completions = getCommandCompletions(line);
    const tooltip = getCommandTooltip(line);

    let hint = '';

    if (completions.length === 1 && completions[0] !== line) {
      // Show the remaining part of the completion as a hint
      hint = completions[0].slice(line.length);
    }

    // Add tooltip if available
    if (tooltip) {
      hint += `  ${colors.gray}— ${tooltip}${colors.reset}`;
    } else if (completions.length > 1) {
      hint += `  ${colors.gray}[${completions.length} options, Tab to complete]${colors.reset}`;
    }

    if (hint && hint !== this.currentHint) {
      this.clearHint();
      this.currentHint = hint;
      // Save cursor, write dim hint, restore cursor
      process.stdout.write(`\x1b[s${colors.dim}${hint}${colors.reset}\x1b[u`);
    } else if (!hint) {
      this.clearHint();
    }
  }

  private clearHint(): void {
    if (this.currentHint) {
      // Clear from cursor to end of line
      process.stdout.write('\x1b[K');
      this.currentHint = '';
    }
  }

  async start(): Promise<void> {
    this.running = true;

    if (this.config.agent && this.config.modelRouter) {
      this.config.agent.setModelTier(this.config.modelRouter.getTier());
    }

    this.rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout,
      completer: (line: string) => {
        const completions = getCommandCompletions(line);
        return [completions, line];
      },
    });

    // In minimal TUI we can prompt inline for tool confirmations.
    // This avoids deadlocks when hooks are configured to require confirmation
    // (e.g. shell.exec) and the tool loop is awaiting a decision.
    if (this.config.hookEngine) {
      this.config.hookEngine.setInteractiveConfirmer(async (pending) => {
        const tool = pending.tool;
        const args = pending.args;
        const argsStr = Object.keys(args).length > 0 ? ` ${JSON.stringify(args)}` : '';
        console.log(`\n${colors.bold}Confirmation required${colors.reset}`);
        console.log(`${colors.gray}${tool}${colors.reset}${argsStr}`);

        const answer = (await this.prompt(`${colors.orange}${colors.bold}Approve?${colors.reset} ${colors.gray}(y/N)${colors.reset} `))
          .trim()
          .toLowerCase();
        const approved = answer === 'y' || answer === 'yes';
        console.log(approved ? `${colors.gray}Approved.${colors.reset}\n` : `${colors.gray}Denied.${colors.reset}\n`);
        return approved ? { approved: true } : { approved: false, reason: 'Denied by user' };
      });
    }

    // Listen for line changes to show hints
    process.stdin.on('keypress', () => {
      // Small delay to let readline update the line
      setImmediate(() => {
        if (this.rl) {
          const line = (this.rl as readline.Interface & { line?: string }).line || '';
          if (line !== this.lastLine) {
            this.lastLine = line;
            this.showHint(line);
          }
        }
      });
    });

    // Enable keypress events
    if (process.stdin.isTTY) {
      readline.emitKeypressEvents(process.stdin);
    }

    console.log(getColoredBanner());
    console.log(`\n${colors.orange}${colors.bold}Flynn TUI${colors.reset} ${colors.dim}(minimal mode)${colors.reset}`);
    console.log(`${colors.gray}Type /help for commands, /fullscreen for panel mode${colors.reset}\n`);

    await this.promptLoop();
  }

  private async promptLoop(): Promise<void> {
    while (this.running && this.rl) {
      this.lastLine = '';
      this.currentHint = '';
      const input = await this.prompt(formatPrompt('default'));
      this.clearHint();
      const command = parseCommand(input);

      if (!command) {
        continue;
      }

      await this.handleCommand(command);
    }
  }

  private prompt(promptText: string): Promise<string> {
    return new Promise((resolve) => {
      if (!this.rl) {
        resolve('');
        return;
      }
      const onClose = () => resolve('');
      this.rl.once('close', onClose);
      this.rl.question(promptText, (answer) => {
        this.rl?.removeListener('close', onClose);
        resolve(answer);
      });
    });
  }

  private async handleCommand(command: Command): Promise<void> {
    switch (command.type) {
      case 'quit':
        this.stop();
        break;

      case 'reset':
        this.config.session.clear();
        this.totalUsage = { inputTokens: 0, outputTokens: 0 };
        console.log(`${colors.gray}Session cleared.${colors.reset}\n`);
        break;

      case 'help':
        console.log(getHelpText() + '\n');
        break;

      case 'status':
        this.printStatus();
        break;

      case 'fullscreen':
        this.config.onFullscreen?.();
        break;

      case 'model':
        this.handleModelCommand(command.name, command.providerModel);
        break;

      case 'backend':
        await this.handleBackendCommand(command.provider);
        break;

      case 'login':
        await this.handleLoginCommand(command.provider);
        break;

      case 'pair':
        this.handlePairCommand(command.action, command.args);
        break;

      case 'transfer':
        this.config.onTransfer?.(command.target);
        break;

      case 'message':
        await this.handleMessage(command.content);
        break;
    }
  }

  private handleModelCommand(name?: string, providerModel?: string): void {
    const router = this.config.modelRouter;
    if (!router) {
      console.log(`${colors.gray}Model switching not available.${colors.reset}\n`);
      return;
    }

    // /model <tier> <provider/model> — change a tier's provider and model
    if (name && providerModel) {
      const tier = resolveModelAlias(name);
      const slashIdx = providerModel.indexOf('/');
      if (slashIdx === -1) {
        console.log(`${colors.gray}Invalid format. Use provider/model (e.g. anthropic/claude-sonnet-4)${colors.reset}\n`);
        return;
      }
      const provider = providerModel.slice(0, slashIdx);
      const model = providerModel.slice(slashIdx + 1);

      if (!MODEL_PROVIDERS.includes(provider as ModelProvider)) {
        console.log(`${colors.gray}Unknown provider "${provider}". Known providers: ${MODEL_PROVIDERS.join(', ')}${colors.reset}\n`);
        return;
      }

      try {
        const providerType = provider as ModelProvider;
        const template = this.config.modelProviderConfigs?.[providerType];
        const client = createClientFromConfig({
          ...(template ?? {}),
          provider: providerType,
          model,
        });
        router.setClient(tier, client, providerModel);
        router.setTierStrict(tier, true);
        router.setTier(tier);

        if (this.config.agent) {
          this.config.agent.setModelTier(tier);
        }

        console.log(`${colors.gray}Set ${tier} to:${colors.reset} ${providerModel}`);
        console.log(`${colors.gray}Switched to model:${colors.reset} ${tier}`);
        console.log(`${colors.gray}Fallbacks for ${tier} disabled (strict tier mode).${colors.reset}\n`);
      } catch (error) {
        const message = error instanceof Error ? error.message : String(error);
        console.log(`${colors.gray}Failed to create client:${colors.reset} ${message}\n`);
      }
      return;
    }

    // /model — show all tiers with labels
    if (!name) {
      const current = router.getTier();
      const available = router.getAvailableTiers();
      const labels = router.getAllLabels();
      console.log(`${colors.gray}Active tier:${colors.reset} ${current}`);
      for (const tier of available) {
        const label = labels[tier] ?? 'unknown';
        const marker = tier === current ? ' ←' : '';
        console.log(`  ${tier}: ${label}${marker}`);
      }
      console.log();
      return;
    }

    // /model <tier> — switch active tier
    const tier = resolveModelAlias(name);
    if (router.setTier(tier)) {
      // Also update the agent tier so chatWithRouter uses the correct client
      if (this.config.agent) {
        this.config.agent.setModelTier(tier);
      }
      console.log(`${colors.gray}Switched to model:${colors.reset} ${tier}\n`);
    } else {
      console.log(`${colors.gray}Model not available:${colors.reset} ${name}\n`);
    }
  }

  private async handleBackendCommand(provider?: string): Promise<void> {
    const router = this.config.modelRouter;
    if (!router) {
      console.log('Backend switching not available.\n');
      return;
    }

    if (!provider) {
      const current = router.getLocalProviderName() ?? this.config.currentLocalProvider ?? 'unknown';
      const available = this.getAvailableBackends();
      console.log(`Current local backend: ${current}`);
      console.log(`Available: ${available.join(', ')}\n`);
      return;
    }

    const providerConfig = this.config.localProviders?.[provider];
    if (!providerConfig) {
      const available = this.getAvailableBackends();
      console.log(`Backend '${provider}' not configured.`);
      console.log(`Available: ${available.join(', ')}\n`);
      return;
    }

    // Stop current daemon if running
    const currentBackend = router.getLocalProviderName();
    if (currentBackend && currentBackend !== provider) {
      console.log(`${colors.gray}Stopping ${currentBackend}...${colors.reset}`);
      await this.stopBackend(currentBackend);
    }

    // Start new daemon
    console.log(`${colors.gray}Starting ${provider}...${colors.reset}`);
    await this.startBackend(provider, providerConfig);

    const client = this.createLocalClient(providerConfig);
    if (!client) {
      console.log(`Failed to create client for '${provider}'.\n`);
      return;
    }

    router.setLocalClient(client, provider);
    console.log(`${colors.gray}Switched to backend: ${provider}${colors.reset}\n`);
  }

  private async stopBackend(provider: string): Promise<void> {
    try {
      const { exec } = await import('child_process');
      let serviceName: string;
      switch (provider) {
        case 'ollama':
          serviceName = 'ollama.service';
          break;
        case 'llamacpp':
          serviceName = 'llama-server.service';
          break;
        default:
          return;
      }
      await new Promise<void>((resolve, reject) => {
        exec(`systemctl --user stop ${serviceName}`, (error) => {
          if (error) {
            reject(error);
          } else {
            resolve();
          }
        });
      });
    } catch (error) {
      // Service might not exist or already stopped, ignore
      console.log(`${colors.gray}Note: ${provider} service not managed by systemd${colors.reset}\n`);
    }
  }

  private async startBackend(provider: string, config: ModelConfig): Promise<void> {
    try {
      const { exec } = await import('child_process');
      let serviceName: string;
      switch (provider) {
        case 'ollama':
          serviceName = 'ollama.service';
          break;
        case 'llamacpp':
          serviceName = 'llama-server.service';
          break;
        default:
          return;
      }
      await new Promise<void>((resolve, reject) => {
        exec(`systemctl --user start ${serviceName}`, (error) => {
          if (error) {
            reject(error);
          } else {
            resolve();
          }
        });
      });

      // Wait briefly for daemon to start
      await new Promise(resolve => setTimeout(resolve, 500));
    } catch (error) {
      console.log(`${colors.gray}Warning: Failed to start ${provider} via systemd: ${error instanceof Error ? error.message : String(error)}${colors.reset}\n`);
    }
  }

  private async handleLoginCommand(provider?: string): Promise<void> {
    const target = provider ?? 'github';

    const promptHidden = async (question: string): Promise<string> => {
      const rl = readline.createInterface({ input: process.stdin, output: process.stdout, terminal: true });
      const rlAny = rl as any;
      rlAny.stdoutMuted = true;
      rlAny._writeToOutput = (s: string) => {
        if (!rlAny.stdoutMuted) {
          process.stdout.write(s);
          return;
        }
        if (s.includes('\n')) {
          process.stdout.write('\n');
        } else {
          process.stdout.write('*');
        }
      };
      const answer = await new Promise<string>((resolve) => rl.question(question, resolve));
      rlAny.stdoutMuted = false;
      rl.close();
      process.stdout.write('\n');
      return answer.trim();
    };

    if (!this.rl) {
      console.log(`${colors.gray}TUI not ready for login prompt. Use the CLI auth commands instead.${colors.reset}\n`);
      return;
    }
    if (target === 'github') {
      console.log(`${colors.gray}Starting GitHub OAuth device flow...${colors.reset}`);

      try {
        await loginGitHub((userCode, verificationUri) => {
          console.log('');
          console.log(`${colors.gray}Please visit:${colors.reset} ${verificationUri}`);
          console.log(`${colors.gray}and enter code:${colors.reset} ${userCode}`);
          console.log('');
          console.log(`${colors.gray}Waiting for authorization...${colors.reset}`);
        });

        console.log(`${colors.gray}GitHub authentication successful! Token stored.${colors.reset}\n`);
      } catch (error) {
        const message = error instanceof Error ? error.message : String(error);
        console.log(`${colors.gray}GitHub login failed:${colors.reset} ${message}\n`);
      }

      return;
    }

    if (target === 'openai') {
      console.log(`${colors.gray}OpenAI login:${colors.reset}`);
      console.log(`${colors.gray}  1) OAuth device flow  2) Paste API key${colors.reset}`);
      const choice = (await this.prompt(`${colors.orange}Choose [1-2] (default 1):${colors.reset} `)).trim();

      // 2) API key
      if (choice === '2') {
        const existing = loadStoredOpenAIApiKey();
        if (existing) {
          console.log(`${colors.gray}OpenAI API key already exists.${colors.reset}`);
          console.log(`${colors.gray}Delete ~/.config/flynn/auth.json openai.api_key entry to re-authenticate.${colors.reset}\n`);
          return;
        }

        console.log(`${colors.gray}OpenAI uses API keys for standard API access.${colors.reset}`);
        console.log(`${colors.gray}Create a key at:${colors.reset} https://platform.openai.com/api-keys`);
        console.log('');

        try {
          this.rl.pause();
          const apiKey = await promptHidden('Enter OpenAI API key: ');
          storeOpenAIApiKey(apiKey);
          console.log('');
          console.log(`${colors.gray}OpenAI API key stored in ~/.config/flynn/auth.json${colors.reset}\n`);
        } catch (error) {
          const message = error instanceof Error ? error.message : String(error);
          console.log(`${colors.gray}OpenAI API key storage failed:${colors.reset} ${message}\n`);
        } finally {
          this.rl.resume();
        }

        return;
      }

      // 1) OAuth device flow (default)
      const existing = loadStoredOpenAIAuth();
      if (existing) {
        console.log(`${colors.gray}OpenAI OAuth token already exists.${colors.reset}`);
        console.log(`${colors.gray}Delete ~/.config/flynn/auth.json openai.oauth entry (or legacy openai entry) to re-authenticate.${colors.reset}\n`);
        return;
      }

      console.log(`${colors.gray}Starting OpenAI OAuth device flow...${colors.reset}`);

      try {
        await loginOpenAI((userCode, verificationUri) => {
          console.log('');
          console.log(`${colors.gray}Please visit:${colors.reset} ${verificationUri}`);
          console.log(`${colors.gray}and enter code:${colors.reset} ${userCode}`);
          console.log('');
          console.log(`${colors.gray}Waiting for authorization...${colors.reset}`);
        });

        console.log(`${colors.gray}OpenAI authentication successful! Token stored.${colors.reset}\n`);
      } catch (error) {
        const message = error instanceof Error ? error.message : String(error);
        console.log(`${colors.gray}OpenAI login failed:${colors.reset} ${message}\n`);
      }

      return;
    }

    if (target === 'anthropic') {
      console.log(`${colors.gray}Anthropic login:${colors.reset}`);
      console.log(`${colors.gray}  1) Paste API key  2) Paste auth token${colors.reset}`);
      const choice = (await this.prompt(`${colors.orange}Choose [1-2] (default 1):${colors.reset} `)).trim();

      const existing = loadStoredAnthropicAuth();
      const hasApiKey = Boolean(existing?.api_key);
      const hasToken = Boolean(loadStoredAnthropicAuthToken());

      // 2) Auth token
      if (choice === '2') {
        if (hasToken) {
          console.log(`${colors.gray}Anthropic auth token already exists.${colors.reset}`);
          console.log(`${colors.gray}Delete ~/.config/flynn/auth.json anthropic.auth_token entry to re-authenticate.${colors.reset}\n`);
          return;
        }

        console.log(`${colors.gray}Anthropic supports token-style auth (provider-specific).${colors.reset}`);
        console.log('');

        try {
          this.rl.pause();
          const token = await promptHidden('Enter Anthropic auth token: ');
          storeAnthropicAuthToken(token);
          console.log('');
          console.log(`${colors.gray}Anthropic auth token stored in ~/.config/flynn/auth.json${colors.reset}\n`);
        } catch (error) {
          const message = error instanceof Error ? error.message : String(error);
          console.log(`${colors.gray}Anthropic auth failed:${colors.reset} ${message}\n`);
        } finally {
          this.rl.resume();
        }

        return;
      }

      // 1) API key (default)
      if (hasApiKey) {
        console.log(`${colors.gray}Anthropic API key already exists.${colors.reset}`);
        console.log(`${colors.gray}Delete ~/.config/flynn/auth.json anthropic.api_key entry to re-authenticate.${colors.reset}\n`);
        return;
      }

      console.log(`${colors.gray}Anthropic uses API keys for authentication.${colors.reset}`);
      console.log(`${colors.gray}Create a key at:${colors.reset} https://console.anthropic.com/settings/keys`);
      console.log('');

      try {
        this.rl.pause();
        const apiKey = await promptHidden('Enter Anthropic API key: ');
        storeAnthropicAuth(apiKey);
        console.log('');
        console.log(`${colors.gray}Anthropic API key stored in ~/.config/flynn/auth.json${colors.reset}\n`);
      } catch (error) {
        const message = error instanceof Error ? error.message : String(error);
        console.log(`${colors.gray}Anthropic auth failed:${colors.reset} ${message}\n`);
      } finally {
        this.rl.resume();
      }

      return;
    }

    if (target === 'zai' || target === 'zhipuai') {
      const existing = loadStoredZaiAuth();
      if (existing) {
        console.log(`${colors.gray}Z.AI credential already exists.${colors.reset}`);
        console.log(`${colors.gray}Delete ~/.config/flynn/auth.json zai/zhipuai entry to re-authenticate.${colors.reset}\n`);
        return;
      }

      console.log(`${colors.gray}Z.AI uses API keys (HTTP Bearer), not an OAuth device flow.${colors.reset}`);
      console.log(`${colors.gray}Create a key at:${colors.reset} https://z.ai/manage-apikey/apikey-list`);
      console.log(`${colors.gray}Choose mode: 1) API  2) Coding Plan${colors.reset}`);
      const choice = (await this.prompt(`${colors.orange}Select [1-2] (default 1):${colors.reset} `)).trim().toLowerCase();
      const mode = (choice === '2' || choice === 'plan') ? 'plan' : 'api';
      console.log('');

      try {
        this.rl.pause();
        const apiKey = await promptHidden('Enter Z.AI API key: ');
        storeZaiAuth(apiKey);
        console.log('');
        console.log(`${colors.gray}Z.AI credential stored in ~/.config/flynn/auth.json${colors.reset}`);
        if (mode === 'plan') {
          console.log(`${colors.gray}Mode: Coding Plan${colors.reset}`);
          console.log(`${colors.gray}Set endpoint to https://api.z.ai/api/coding/paas/v4${colors.reset}\n`);
        } else {
          console.log(`${colors.gray}Mode: API${colors.reset}`);
          console.log(`${colors.gray}Set endpoint to https://api.z.ai/api/paas/v4${colors.reset}\n`);
        }
      } catch (error) {
        const message = error instanceof Error ? error.message : String(error);
        console.log(`${colors.gray}Z.AI auth failed:${colors.reset} ${message}\n`);
      } finally {
        this.rl.resume();
      }

      return;
    }

    console.log(`${colors.gray}Unknown login provider:${colors.reset} ${target}. Supported: github, openai, anthropic, zai\n`);
  }

  private handlePairCommand(action?: 'generate' | 'list' | 'revoke', args?: string): void {
    const pm = this.config.pairingManager;
    if (!pm) {
      console.log(`${colors.gray}Pairing not enabled. Set pairing.enabled: true in config.${colors.reset}\n`);
      return;
    }

    switch (action) {
      case 'generate': {
        const code = pm.generateCode(args);
        const pending = pm.listPendingCodes().find(p => p.code === code);
        const expiresIn = pending ? Math.round((pending.expiresAt - Date.now()) / 1000) : '?';
        console.log(`${colors.bold}Pairing code: ${code}${colors.reset}`);
        console.log(`${colors.gray}Expires in ${expiresIn}s${args ? ` (label: ${args})` : ''}${colors.reset}\n`);
        break;
      }

      case 'revoke': {
        if (!args) {
          console.log(`${colors.gray}Usage: /pair revoke <channel> <senderId>${colors.reset}\n`);
          return;
        }
        const parts = args.split(/\s+/);
        if (parts.length < 2) {
          console.log(`${colors.gray}Usage: /pair revoke <channel> <senderId>${colors.reset}\n`);
          return;
        }
        const [channel, senderId] = parts;
        const revoked = pm.revokeApproval(channel, senderId);
        if (revoked) {
          console.log(`${colors.bold}Revoked approval for ${channel}:${senderId}${colors.reset}\n`);
        } else {
          console.log(`${colors.gray}No approval found for ${channel}:${senderId}${colors.reset}\n`);
        }
        break;
      }

      case 'list':
      default: {
        const pending = pm.listPendingCodes();
        const approved = pm.listApproved();

        if (pending.length === 0 && approved.length === 0) {
          console.log(`${colors.gray}No pending codes or approved senders.${colors.reset}\n`);
          return;
        }

        if (pending.length > 0) {
          console.log(`${colors.bold}Pending codes:${colors.reset}`);
          for (const p of pending) {
            const expiresIn = Math.round((p.expiresAt - Date.now()) / 1000);
            console.log(`  ${p.code}  expires in ${expiresIn}s${p.label ? `  (${p.label})` : ''}`);
          }
        }

        if (approved.length > 0) {
          console.log(`${colors.bold}Approved senders:${colors.reset}`);
          for (const a of approved) {
            const date = new Date(a.approvedAt).toISOString().slice(0, 16).replace('T', ' ');
            console.log(`  ${a.channel}:${a.senderId}  since ${date}  (code: ${a.codeUsed})`);
          }
        }
        console.log('');
        break;
      }
    }
  }

  private getAvailableBackends(): string[] {
    const backends: string[] = [];
    if (this.config.currentLocalProvider) {
      backends.push(this.config.currentLocalProvider);
    }
    if (this.config.localProviders) {
      backends.push(...Object.keys(this.config.localProviders));
    }
    return [...new Set(backends)];
  }

  private createLocalClient(config: ModelConfig): ModelClient | null {
    if (config.provider === 'ollama') {
      return new OllamaClient({
        model: config.model,
        host: config.endpoint,
      });
    }
    if (config.provider === 'llamacpp') {
      return new LlamaCppClient({
        endpoint: config.endpoint ?? 'http://localhost:8080',
        model: config.model,
        authToken: config.auth_token,
      });
    }
    return null;
  }

  private printStatus(): void {
    console.log(`${colors.gray}Session:${colors.reset} ${this.config.session.id}`);
    console.log(`${colors.gray}Messages:${colors.reset} ${this.config.session.getHistory().length}`);
    console.log(`${colors.gray}Tokens:${colors.reset} ${this.totalUsage.inputTokens} in / ${this.totalUsage.outputTokens} out\n`);
  }

  private async handleMessage(content: string): Promise<void> {
    // Print Flynn label before response
    process.stdout.write(`\n${colors.orange}${colors.bold}Flynn:${colors.reset}\n`);

    try {
      // Use agent if available (supports tool loop)
      if (this.config.agent) {
        const response = await this.config.agent.process(content);
        const rendered = renderMarkdown(response);
        console.log(rendered);
        console.log();
        return;
      }

      // Fallback: direct model client (no tool support)
      this.config.session.addMessage({ role: 'user', content });

      // Try streaming if available
      if (this.config.modelClient.chatStream) {
        let fullContent = '';

        for await (const event of this.config.modelClient.chatStream({
          messages: this.config.session.getHistory(),
          system: this.config.systemPrompt,
        })) {
          if (event.type === 'content' && event.content) {
            process.stdout.write(event.content);
            fullContent += event.content;
          }
          if (event.type === 'fallback_warning' && event.fallbackReason) {
            console.warn('\n⚠ Using fallback model');
          }
          if (event.type === 'done' && event.usage) {
            this.totalUsage.inputTokens += event.usage.inputTokens;
            this.totalUsage.outputTokens += event.usage.outputTokens;
          }
          if (event.type === 'error') {
            throw event.error ?? new Error('Stream error');
          }
        }

        console.log('\n');

        this.config.session.addMessage({ role: 'assistant', content: fullContent });
      } else {
        // Fallback to non-streaming
        const response = await this.config.modelClient.chat({
          messages: this.config.session.getHistory(),
          system: this.config.systemPrompt,
        });

        const rendered = renderMarkdown(response.content);
        console.log(rendered);
        console.log();

        this.totalUsage.inputTokens += response.usage.inputTokens;
        this.totalUsage.outputTokens += response.usage.outputTokens;

        this.config.session.addMessage({ role: 'assistant', content: response.content });
      }
    } catch (error) {
      console.error('Error:', error instanceof Error ? error.message : error);
      console.log();
    }
  }

  stop(preserveStdin = false): void {
    this.running = false;
    if (this.rl) {
      if (preserveStdin) {
        // Remove readline listeners but don't close stdin
        this.rl.removeAllListeners();
        process.stdin.removeAllListeners('keypress');
        // Pause stdin so readline releases it
        process.stdin.pause();
      }
      this.rl.close();
      this.rl = null;
    }
    // Clean up keypress listener
    process.stdin.removeAllListeners('keypress');
  }
}