// Aider Runner — Node.js sidecar entry point for Aider coding agent
// Spawned by Rust SidecarManager, communicates via stdio NDJSON
// Runs aider in interactive mode — persistent process with stdin/stdout chat
// Pre-fetches btmsg/bttask context so the LLM has actionable data immediately.

import { stdin, stdout, stderr } from 'process';
import { createInterface } from 'readline';
import { spawn, execSync, type ChildProcess } from 'child_process';
import { accessSync, constants } from 'fs';
import { join } from 'path';

const rl = createInterface({ input: stdin });

interface AiderSession {
  process: ChildProcess;
  controller: AbortController;
  sessionId: string;
  model: string;
  lineBuffer: string;        // partial line accumulator for streaming
  turnBuffer: string;        // full turn output
  turnStartTime: number;
  turns: number;
  ready: boolean;
  env: Record<string, string>;
  cwd: string;
}

const sessions = new Map<string, AiderSession>();

function send(msg: Record<string, unknown>) {
  stdout.write(JSON.stringify(msg) + '\n');
}

function log(message: string) {
  stderr.write(`[aider-sidecar] ${message}\n`);
}

rl.on('line', (line: string) => {
  try {
    const msg = JSON.parse(line);
    handleMessage(msg).catch((err: unknown) => {
      log(`Unhandled error in message handler: ${err}`);
    });
  } catch {
    log(`Invalid JSON: ${line}`);
  }
});

interface QueryMessage {
  type: 'query';
  sessionId: string;
  prompt: string;
  cwd?: string;
  model?: string;
  systemPrompt?: string;
  extraEnv?: Record<string, string>;
  providerConfig?: Record<string, unknown>;
}

interface StopMessage {
  type: 'stop';
  sessionId: string;
}

async function handleMessage(msg: Record<string, unknown>) {
  switch (msg.type) {
    case 'ping':
      send({ type: 'pong' });
      break;
    case 'query':
      await handleQuery(msg as unknown as QueryMessage);
      break;
    case 'stop':
      handleStop(msg as unknown as StopMessage);
      break;
    default:
      send({ type: 'error', message: `Unknown message type: ${msg.type}` });
  }
}

// --- Context pre-fetching ---
// Execute btmsg/bttask CLIs to gather context BEFORE sending prompt to LLM.
// This way the LLM gets real data to act on instead of suggesting commands.

function runCmd(cmd: string, env: Record<string, string>, cwd: string): string | null {
  try {
    const result = execSync(cmd, { env, cwd, timeout: 5000, encoding: 'utf-8' }).trim();
    log(`[prefetch] ${cmd} → ${result.length} chars`);
    return result || null;
  } catch (e: unknown) {
    log(`[prefetch] ${cmd} FAILED: ${e instanceof Error ? e.message : String(e)}`);
    return null;
  }
}

function prefetchContext(env: Record<string, string>, cwd: string): string {
  log(`[prefetch] BTMSG_AGENT_ID=${env.BTMSG_AGENT_ID ?? 'NOT SET'}, cwd=${cwd}`);
  const parts: string[] = [];

  const inbox = runCmd('btmsg inbox', env, cwd);
  if (inbox) {
    parts.push(`## Your Inbox\n\`\`\`\n${inbox}\n\`\`\``);
  } else {
    parts.push('## Your Inbox\nNo messages (or btmsg unavailable).');
  }

  const board = runCmd('bttask board', env, cwd);
  if (board) {
    parts.push(`## Task Board\n\`\`\`\n${board}\n\`\`\``);
  } else {
    parts.push('## Task Board\nNo tasks (or bttask unavailable).');
  }

  return parts.join('\n\n');
}

// --- Prompt detection ---
// Aider with --no-pretty --no-fancy-input shows prompts like:
//   >  or  aider>  or  repo-name>
const PROMPT_RE = /^[a-zA-Z0-9._-]*> $/;

function looksLikePrompt(buffer: string): boolean {
  // Check the last non-empty line
  const lines = buffer.split('\n');
  for (let i = lines.length - 1; i >= 0; i--) {
    const l = lines[i];
    if (l.trim() === '') continue;
    return PROMPT_RE.test(l);
  }
  return false;
}

// Lines to suppress from UI (aider startup noise)
const SUPPRESS_RE = [
  /^Aider v\d/,
  /^Main model:/,
  /^Weak model:/,
  /^Git repo:/,
  /^Repo-map:/,
  /^Use \/help/,
];

function shouldSuppress(line: string): boolean {
  const t = line.trim();
  return t === '' || SUPPRESS_RE.some(p => p.test(t));
}

// --- Shell command execution ---
// Runs a shell command and returns {stdout, stderr, exitCode}

function execShell(cmd: string, env: Record<string, string>, cwd: string): { stdout: string; exitCode: number } {
  try {
    const result = execSync(cmd, { env, cwd, timeout: 30000, encoding: 'utf-8', stdio: ['pipe', 'pipe', 'pipe'] });
    return { stdout: result.trim(), exitCode: 0 };
  } catch (e: unknown) {
    const err = e as { stdout?: string; stderr?: string; status?: number };
    return { stdout: (err.stdout ?? err.stderr ?? String(e)).trim(), exitCode: err.status ?? 1 };
  }
}

// --- Turn output parsing ---
// Parses complete turn output into structured blocks:
// thinking, answer text, shell commands, cost info

interface TurnBlock {
  type: 'thinking' | 'text' | 'shell' | 'cost';
  content: string;
}

// Known shell command patterns — commands from btmsg/bttask/common tools
const SHELL_CMD_RE = /^(btmsg |bttask |cat |ls |find |grep |mkdir |cd |cp |mv |rm |pip |npm |git |curl |wget |python |node |bash |sh )/;

function parseTurnOutput(buffer: string): TurnBlock[] {
  const blocks: TurnBlock[] = [];
  const lines = buffer.split('\n');

  let thinkingLines: string[] = [];
  let answerLines: string[] = [];
  let inThinking = false;
  let inAnswer = false;
  let inCodeBlock = false;
  let codeBlockLang = '';
  let codeBlockLines: string[] = [];

  for (const line of lines) {
    const t = line.trim();

    // Skip suppressed lines
    if (shouldSuppress(line) && !inCodeBlock) continue;

    // Prompt markers — skip
    if (PROMPT_RE.test(t)) continue;

    // Thinking block markers (handle various unicode arrows and spacing)
    if (/^[►▶⯈❯>]\s*THINKING$/i.test(t)) {
      inThinking = true;
      inAnswer = false;
      continue;
    }
    if (/^[►▶⯈❯>]\s*ANSWER$/i.test(t)) {
      if (thinkingLines.length > 0) {
        blocks.push({ type: 'thinking', content: thinkingLines.join('\n') });
        thinkingLines = [];
      }
      inThinking = false;
      inAnswer = true;
      continue;
    }

    // Code block detection (```bash, ```shell, ```)
    if (t.startsWith('```') && !inCodeBlock) {
      inCodeBlock = true;
      codeBlockLang = t.slice(3).trim().toLowerCase();
      codeBlockLines = [];
      continue;
    }
    if (t === '```' && inCodeBlock) {
      inCodeBlock = false;
      // If this was a bash/shell code block, extract commands
      if (['bash', 'shell', 'sh', ''].includes(codeBlockLang)) {
        for (const cmdLine of codeBlockLines) {
          const cmd = cmdLine.trim().replace(/^\$ /, '');
          if (cmd && SHELL_CMD_RE.test(cmd)) {
            if (answerLines.length > 0) {
              blocks.push({ type: 'text', content: answerLines.join('\n') });
              answerLines = [];
            }
            blocks.push({ type: 'shell', content: cmd });
          }
        }
      }
      codeBlockLines = [];
      continue;
    }
    if (inCodeBlock) {
      codeBlockLines.push(line);
      continue;
    }

    // Cost line
    if (/^Tokens: .+Cost:/.test(t)) {
      blocks.push({ type: 'cost', content: t });
      continue;
    }

    // Shell command ($ prefix or Running prefix)
    if (t.startsWith('$ ') || t.startsWith('Running ')) {
      if (answerLines.length > 0) {
        blocks.push({ type: 'text', content: answerLines.join('\n') });
        answerLines = [];
      }
      blocks.push({ type: 'shell', content: t.replace(/^(Running |\$ )/, '') });
      continue;
    }

    // Detect bare btmsg/bttask commands in answer text
    if (inAnswer && SHELL_CMD_RE.test(t) && !t.includes('`') && !t.startsWith('#')) {
      if (answerLines.length > 0) {
        blocks.push({ type: 'text', content: answerLines.join('\n') });
        answerLines = [];
      }
      blocks.push({ type: 'shell', content: t });
      continue;
    }

    // Aider's "Applied edit" / flake8 output — suppress from answer text
    if (/^Applied edit to |^Fix any errors|^Running: /.test(t)) continue;

    // Accumulate into thinking or answer
    if (inThinking) {
      thinkingLines.push(line);
    } else {
      answerLines.push(line);
    }
  }

  // Flush remaining
  if (thinkingLines.length > 0) {
    blocks.push({ type: 'thinking', content: thinkingLines.join('\n') });
  }
  if (answerLines.length > 0) {
    blocks.push({ type: 'text', content: answerLines.join('\n').trim() });
  }

  return blocks;
}

// --- Main query handler ---

async function handleQuery(msg: QueryMessage) {
  const { sessionId, prompt, cwd: cwdOpt, model, systemPrompt, extraEnv, providerConfig } = msg;
  const cwd = cwdOpt || process.cwd();

  // Build environment
  const env: Record<string, string> = { ...process.env as Record<string, string> };
  if (extraEnv) Object.assign(env, extraEnv);
  if (providerConfig?.openrouterApiKey && typeof providerConfig.openrouterApiKey === 'string') {
    env.OPENROUTER_API_KEY = providerConfig.openrouterApiKey;
  }

  const existing = sessions.get(sessionId);

  // Follow-up prompt on existing session
  if (existing && existing.process.exitCode === null) {
    log(`Continuing session ${sessionId} with follow-up prompt`);
    existing.turnBuffer = '';
    existing.lineBuffer = '';
    existing.turnStartTime = Date.now();
    existing.turns++;

    send({ type: 'agent_started', sessionId });

    // Show the incoming prompt in the console
    send({
      type: 'agent_event',
      sessionId,
      event: { type: 'input', prompt },
    });

    // Pre-fetch fresh context for follow-up turns too
    const ctx = prefetchContext(existing.env, existing.cwd);
    const fullPrompt = `${ctx}\n\nNow act on the above. Your current task:\n${prompt}`;
    existing.process.stdin?.write(fullPrompt + '\n');
    return;
  }

  // New session — spawn aider
  const aiderPath = which('aider');
  if (!aiderPath) {
    send({ type: 'agent_error', sessionId, message: 'Aider not found. Install with: pipx install aider-chat' });
    return;
  }

  const aiderModel = model || 'openrouter/anthropic/claude-sonnet-4';
  log(`Starting Aider session ${sessionId} with model ${aiderModel}`);

  const controller = new AbortController();

  const args: string[] = [
    '--model', aiderModel,
    '--yes-always',
    '--no-pretty',
    '--no-fancy-input',
    '--no-stream',                     // Complete responses (no token fragments)
    '--no-git',
    '--no-auto-commits',
    '--suggest-shell-commands',
    '--no-check-model-accepts-settings',
  ];

  if (providerConfig?.editFormat && typeof providerConfig.editFormat === 'string') {
    args.push('--edit-format', providerConfig.editFormat);
  }
  if (providerConfig?.architect === true) {
    args.push('--architect');
  }

  send({ type: 'agent_started', sessionId });
  send({
    type: 'agent_event',
    sessionId,
    event: { type: 'system', subtype: 'init', session_id: sessionId, model: aiderModel, cwd },
  });

  // Show the incoming prompt in the console
  send({
    type: 'agent_event',
    sessionId,
    event: { type: 'input', prompt },
  });

  const child = spawn(aiderPath, args, {
    cwd,
    env,
    stdio: ['pipe', 'pipe', 'pipe'],
    signal: controller.signal,
  });

  const session: AiderSession = {
    process: child,
    controller,
    sessionId,
    model: aiderModel,
    lineBuffer: '',
    turnBuffer: '',
    turnStartTime: Date.now(),
    turns: 0,
    ready: false,
    env,
    cwd,
  };
  sessions.set(sessionId, session);

  // Pre-fetch btmsg/bttask context
  const prefetched = prefetchContext(env, cwd);

  // Build full initial prompt — our context FIRST, with explicit override
  const promptParts: string[] = [];
  promptParts.push(`IMPORTANT: You are an autonomous agent in a multi-agent system. Your PRIMARY job is to act on messages and tasks below, NOT to ask the user for files. You can run shell commands to accomplish tasks. If you need to read files, use shell commands like \`cat\`, \`find\`, \`ls\`. If you need to send messages, use \`btmsg send <agent-id> "message"\`. If you need to update tasks, use \`bttask status <task-id> done\`.`);
  if (systemPrompt) promptParts.push(systemPrompt);
  promptParts.push(prefetched);
  promptParts.push(`---\n\nNow act on the above. Your current task:\n${prompt}`);
  const fullPrompt = promptParts.join('\n\n');

  // Startup buffer — wait for first prompt before sending
  let startupBuffer = '';

  child.stdout?.on('data', (data: Buffer) => {
    const text = data.toString();

    // Phase 1: wait for aider startup to finish
    if (!session.ready) {
      startupBuffer += text;
      if (looksLikePrompt(startupBuffer)) {
        session.ready = true;
        session.turns = 1;
        session.turnStartTime = Date.now();
        log(`Aider ready, sending initial prompt (${fullPrompt.length} chars)`);
        child.stdin?.write(fullPrompt + '\n');
      }
      return;
    }

    // Phase 2: accumulate entire turn output, emit as batched blocks
    session.turnBuffer += text;

    // Only process when turn is complete (aider shows prompt again)
    if (!looksLikePrompt(session.turnBuffer)) return;

    const duration = Date.now() - session.turnStartTime;
    const blocks = parseTurnOutput(session.turnBuffer);

    // Emit structured blocks and execute shell commands
    const shellResults: string[] = [];

    for (const block of blocks) {
      switch (block.type) {
        case 'thinking':
          send({
            type: 'agent_event',
            sessionId,
            event: { type: 'thinking', content: block.content },
          });
          break;

        case 'text':
          if (block.content) {
            send({
              type: 'agent_event',
              sessionId,
              event: { type: 'assistant', message: { role: 'assistant', content: block.content } },
            });
          }
          break;

        case 'shell': {
          const cmdId = `shell-${Date.now()}-${Math.random().toString(36).slice(2, 6)}`;

          // Emit tool_use (command being run)
          send({
            type: 'agent_event',
            sessionId,
            event: {
              type: 'tool_use',
              id: cmdId,
              name: 'Bash',
              input: { command: block.content },
            },
          });

          // Actually execute the command
          log(`[exec] Running: ${block.content}`);
          const result = execShell(block.content, session.env, session.cwd);
          const output = result.stdout || '(no output)';

          // Emit tool_result (command output)
          send({
            type: 'agent_event',
            sessionId,
            event: {
              type: 'tool_result',
              tool_use_id: cmdId,
              content: output,
            },
          });

          shellResults.push(`$ ${block.content}\n${output}`);
          break;
        }

        case 'cost':
          // Parsed below for the result event
          break;
      }
    }

    // Extract cost and emit result
    const costMatch = session.turnBuffer.match(/Cost: \$([0-9.]+) message, \$([0-9.]+) session/);
    const costUsd = costMatch ? parseFloat(costMatch[2]) : 0;

    send({
      type: 'agent_event',
      sessionId,
      event: {
        type: 'result',
        subtype: 'result',
        result: '',
        cost_usd: costUsd,
        duration_ms: duration,
        num_turns: session.turns,
        is_error: false,
        session_id: sessionId,
      },
    });

    send({ type: 'agent_stopped', sessionId, exitCode: 0, signal: null });
    session.turnBuffer = '';

    // If commands were executed, feed results back to aider for next turn
    if (shellResults.length > 0 && child.exitCode === null) {
      const feedback = `The following commands were executed and here are the results:\n\n${shellResults.join('\n\n')}\n\nBased on these results, continue your work. If the task is complete, say "DONE".`;
      log(`[exec] Feeding ${shellResults.length} command results back to aider`);
      session.turnBuffer = '';
      session.turnStartTime = Date.now();
      session.turns++;
      send({ type: 'agent_started', sessionId });
      child.stdin?.write(feedback + '\n');
    }
  });

  child.stderr?.on('data', (data: Buffer) => {
    for (const line of data.toString().split('\n')) {
      if (line.trim()) log(`[stderr] ${line}`);
    }
  });

  child.on('close', (code: number | null, signal: string | null) => {
    sessions.delete(sessionId);
    if (controller.signal.aborted) {
      send({ type: 'agent_stopped', sessionId, exitCode: null, signal: 'SIGTERM' });
    } else if (code !== 0 && code !== null) {
      send({ type: 'agent_error', sessionId, message: `Aider exited with code ${code}` });
    } else {
      send({ type: 'agent_stopped', sessionId, exitCode: code, signal });
    }
  });

  child.on('error', (err: Error) => {
    sessions.delete(sessionId);
    log(`Aider spawn error: ${err.message}`);
    send({ type: 'agent_error', sessionId, message: `Failed to start Aider: ${err.message}` });
  });
}

function handleStop(msg: StopMessage) {
  const { sessionId } = msg;
  const session = sessions.get(sessionId);
  if (!session) {
    send({ type: 'error', sessionId, message: 'Session not found' });
    return;
  }

  log(`Stopping Aider session ${sessionId}`);
  session.process.stdin?.write('/exit\n');
  const killTimer = setTimeout(() => {
    session.controller.abort();
    session.process.kill('SIGTERM');
  }, 3000);
  session.process.once('close', () => clearTimeout(killTimer));
}

function which(name: string): string | null {
  const pathDirs = (process.env.PATH || '').split(':');
  for (const dir of pathDirs) {
    const full = join(dir, name);
    try {
      accessSync(full, constants.X_OK);
      return full;
    } catch {
      continue;
    }
  }
  return null;
}

log('Aider sidecar started');
log(`Found aider at: ${which('aider') ?? 'NOT FOUND'}`);
send({ type: 'ready' });