/**
 * compile-agent driver for codex-cli.
 *
 * Codex CLI can run non-interactively with JSONL progress and stdio MCP
 * servers. This mirrors the claude-cli compile path: expose the compile tools
 * through the existing MCP server, let Codex drive the agent loop, and accept
 * success only after the MCP done() tool writes the verified sentinel.
 */

import { type ChildProcess, spawn } from 'node:child_process';
import { existsSync, mkdirSync, readFileSync, unlinkSync, writeFileSync } from 'node:fs';
import { isAbsolute as pathIsAbsolute, join as pathJoin } from 'node:path';
import { type Span, context as otelContext } from '@opentelemetry/api';
import { type SharedModuleManifestEntry, resolvePlanSliceFromFile } from './build-plan.ts';
import type { CompileAgentProgress, CompileAgentResult } from './compile-agent-types.ts';
import { formatCandidateContext, formatToolPlan } from './compile-agent-types.ts';
import { preferredAgentModel } from './llm.ts';
import { createLog } from './log.ts';
import { COMPILE_SENTINELS } from './mcp-compile-server.ts';
import type { SharedCompileContext, ToolCandidate } from './tool-candidates.ts';
import {
  endTraceSpan,
  llmSpanAttributes,
  resolveTraceTokenCount,
  setSpanAttributes,
  startTraceSpan,
  traceJsonInputOutputAttributes,
  traceLlmIoEnabled,
  traceLlmMessages,
  traceToolIoEnabled,
  traced,
} from './tracing.ts';
import type { Session } from './types.ts';

const log = createLog('compile-codex-cli');

const REPO_ROOT = pathJoin(import.meta.dir, '..', '..');
const CLI_PATH = pathJoin(REPO_ROOT, 'src', 'cli.ts');
const MCP_SERVER_NAME = 'imprint-compile';
const MAX_VERIFICATION_CYCLES = 5;

interface CompileViaCodexCliOptions {
  session: Session;
  absoluteToolDir: string;
  sessionPath: string;
  systemPromptPath: string;
  deadlineMs: number;
  startTime: number;
  onProgress?: (p: CompileAgentProgress) => void;
  keepTest?: boolean;
  candidate?: ToolCandidate;
  sharedContext?: SharedCompileContext;
  /** Absolute path to the multi-tool build plan sidecar (.build-plan.json). */
  buildPlanPath?: string;
  /** Shared-module build manifest for this site (verified flags). */
  sharedModules?: SharedModuleManifestEntry[];
  /** Per-tool implementation plan injected into the agent's initial message. */
  toolPlan?: string;
}

interface CodexJsonEvent {
  type: string;
  thread_id?: string;
  item?: {
    id?: string;
    type?: string;
    text?: string;
    content?: unknown;
    name?: string;
    tool_name?: string;
    tool?: string;
    server?: string;
    command?: string[];
    arguments?: unknown;
    args?: unknown;
    input?: unknown;
    result?: unknown;
    output?: unknown;
    error?: unknown;
    status?: string;
    is_error?: boolean;
  };
  usage?: {
    input_tokens?: number;
    output_tokens?: number;
    cached_input_tokens?: number;
    reasoning_output_tokens?: number;
  };
  message?: string;
  error?: { message?: string };
}

export async function compileViaCodexCli(
  opts: CompileViaCodexCliOptions,
): Promise<CompileAgentResult> {
  return await traced(
    'compile.codex_cli_agent',
    'AGENT',
    {
      'imprint.site': opts.session.site,
      'imprint.tool_name': opts.candidate?.toolName,
      'imprint.session_path': opts.sessionPath,
      'imprint.tool_dir': opts.absoluteToolDir,
      'imprint.model': preferredAgentModel('codex-cli'),
    },
    async (span) => {
      const result = await compileViaCodexCliImpl(opts, span);
      setSpanAttributes(span, {
        'imprint.compile.outcome': result.outcome,
        'imprint.compile.success': result.success,
        'imprint.compile.turns': result.turns,
        'imprint.compile.duration_ms': result.durationMs,
        'imprint.compile.input_tokens': result.inputTokens,
        'imprint.compile.output_tokens': result.outputTokens,
        'imprint.compile.conversation_log': result.conversationLogPath,
      });
      return result;
    },
  );
}

async function compileViaCodexCliImpl(
  opts: CompileViaCodexCliOptions,
  traceSpan?: Span,
): Promise<CompileAgentResult> {
  mkdirSync(opts.absoluteToolDir, { recursive: true });
  for (const name of [COMPILE_SENTINELS.done, COMPILE_SENTINELS.giveUp]) {
    const p = pathJoin(opts.absoluteToolDir, name);
    if (existsSync(p)) {
      try {
        unlinkSync(p);
      } catch {
        // best effort
      }
    }
  }

  const bunPath = process.execPath;
  const sessionPathAbs = pathIsAbsolute(opts.sessionPath)
    ? opts.sessionPath
    : pathJoin(REPO_ROOT, opts.sessionPath);
  const mcpArgs = [
    'run',
    CLI_PATH,
    '__mcp-compile-server',
    '--session-path',
    sessionPathAbs,
    '--tool-dir',
    opts.absoluteToolDir,
    ...(opts.candidate ? ['--candidate-json', JSON.stringify(opts.candidate)] : []),
    ...(opts.sharedContext ? ['--shared-context-json', JSON.stringify(opts.sharedContext)] : []),
    ...(opts.buildPlanPath ? ['--build-plan-path', opts.buildPlanPath] : []),
    ...(opts.sharedModules ? ['--shared-modules-json', JSON.stringify(opts.sharedModules)] : []),
  ];

  let systemPrompt: string;
  try {
    systemPrompt = `${readFileSync(opts.systemPromptPath, 'utf8')}\n\nToday's date is ${new Date().toISOString().slice(0, 10)}.`;
  } catch (err) {
    return finalErrorResult(opts, `failed to read system prompt: ${errMsg(err)}`);
  }

  const { assignedSharedModules } = resolvePlanSliceFromFile(
    opts.buildPlanPath,
    opts.candidate?.toolName,
    opts.sharedModules,
  );
  const initialPrompt = `<system_instructions>
${systemPrompt}
</system_instructions>

A new compile task is starting.

Session path: ${sessionPathAbs}
Tool directory: ${opts.absoluteToolDir}
You will write artifacts into the tool directory.
${formatCandidateContext(opts.candidate, opts.sharedContext, assignedSharedModules)}
${formatToolPlan(opts.toolPlan)}

Use the imprint-compile MCP tools to inspect the session, write artifacts, run tests, and call done(). Begin by calling read_session_summary, then proceed per the system instructions.`;

  const model = preferredAgentModel('codex-cli');
  const initialTokenCount = resolveTraceTokenCount(null, initialPrompt);
  const captureLlmIo = traceLlmIoEnabled();
  setSpanAttributes(traceSpan, {
    ...llmSpanAttributes({
      provider: 'codex-cli',
      model,
      inputTokens: initialTokenCount.tokens,
      tokenCountsEstimated: true,
      inputTokenSource: initialTokenCount.source,
      inputMessages: captureLlmIo
        ? traceLlmMessages([{ role: 'user', content: initialPrompt }])
        : undefined,
      inputValue: captureLlmIo ? initialPrompt : undefined,
      invocationParameters: {
        command: 'codex exec',
        json: true,
        sandbox: 'workspace-write',
        tool_timeout_sec: 300,
      },
    }),
    'imprint.compile.initial_prompt_chars': initialPrompt.length,
  });

  const args = [
    '-a',
    'never',
    'exec',
    '--json',
    '--ephemeral',
    '--ignore-user-config',
    '--ignore-rules',
    '--skip-git-repo-check',
    '-C',
    REPO_ROOT,
    '-s',
    'workspace-write',
    '-m',
    model,
    '-c',
    `mcp_servers.${MCP_SERVER_NAME}.command=${JSON.stringify(bunPath)}`,
    '-c',
    `mcp_servers.${MCP_SERVER_NAME}.args=${JSON.stringify(mcpArgs)}`,
    '-c',
    `mcp_servers.${MCP_SERVER_NAME}.default_tools_approval_mode=${JSON.stringify('approve')}`,
    '-c',
    `mcp_servers.${MCP_SERVER_NAME}.tool_timeout_sec=300`,
    '-c',
    'shell_environment_policy.inherit=all',
    '-',
  ];

  log(`spawning codex (mcp-server=${MCP_SERVER_NAME})`);

  let child: ChildProcess;
  try {
    child = spawn('codex', args, {
      cwd: REPO_ROOT,
      env: process.env,
      stdio: ['pipe', 'pipe', 'pipe'],
    });
  } catch (err) {
    return finalErrorResult(opts, `failed to spawn codex-cli: ${errMsg(err)}`);
  }

  try {
    child.stdin?.end(initialPrompt);
  } catch (err) {
    try {
      child.kill('SIGTERM');
    } catch {
      // already gone
    }
    return finalErrorResult(opts, `failed to send prompt to codex-cli: ${errMsg(err)}`);
  }

  const result = await driveJsonl(child, opts, traceSpan);
  const hasActualUsage = result.inputTokens > 0 || result.outputTokens > 0;
  const inputTokenCount = resolveTraceTokenCount(
    hasActualUsage ? result.inputTokens : null,
    initialPrompt,
  );
  const outputTokenCount = resolveTraceTokenCount(
    hasActualUsage ? result.outputTokens : null,
    result.message,
  );
  setSpanAttributes(traceSpan, {
    ...llmSpanAttributes({
      provider: 'codex-cli',
      model,
      inputTokens: inputTokenCount.tokens,
      outputTokens: outputTokenCount.tokens,
      tokenCountsEstimated:
        inputTokenCount.source === 'estimated' || outputTokenCount.source === 'estimated',
      inputTokenSource: inputTokenCount.source,
      outputTokenSource: outputTokenCount.source,
    }),
    'imprint.compile.message': result.message,
  });
  return result;
}

async function driveJsonl(
  child: ChildProcess,
  opts: CompileViaCodexCliOptions,
  traceSpan?: Span,
): Promise<CompileAgentResult> {
  // Capture OTel context so child-process event handlers can parent spans
  // under the current compile.codex_cli_agent span. Bun's event emitters
  // don't propagate AsyncLocalStorage, so without this the agent.turn.*
  // spans appear as orphaned root traces in Phoenix.
  const parentCtx = otelContext.active();

  const conversationLog: unknown[] = [];
  const conversationLogPath = pathJoin(opts.absoluteToolDir, '.compile-log.json');
  const flushLog = (): void => {
    try {
      writeFileSync(conversationLogPath, JSON.stringify(conversationLog, null, 2), 'utf8');
    } catch {}
  };
  let inputTokens = 0;
  let outputTokens = 0;
  let turn = 0;
  let lastErrorMessage = '';
  let stderrBuf = '';
  let agentMessageCount = 0;
  const toolSpans = new Map<string, Span>();
  let currentTurnSpan: Span | null = null;

  const budgetMs = Math.max(0, opts.deadlineMs - Date.now());
  const fireProgress = (phase: 'thinking' | 'tool', toolName?: string): void => {
    opts.onProgress?.({
      turn,
      phase,
      toolName,
      elapsedMs: Date.now() - opts.startTime,
      budgetMs,
      inputTokens,
      outputTokens,
      verificationCycle: 1,
      maxVerificationCycles: MAX_VERIFICATION_CYCLES,
    });
  };

  const doneSentinel = pathJoin(opts.absoluteToolDir, COMPILE_SENTINELS.done);
  const giveUpSentinel = pathJoin(opts.absoluteToolDir, COMPILE_SENTINELS.giveUp);

  const sentinelTimer = setInterval(() => {
    if (!existsSync(doneSentinel) && !existsSync(giveUpSentinel)) return;
    try {
      child.kill('SIGTERM');
    } catch {
      // already gone
    }
  }, 500);

  const deadlineTimer = setTimeout(
    () => {
      log('wall-clock deadline exceeded, terminating codex');
      try {
        child.kill('SIGTERM');
        setTimeout(() => {
          if (!child.killed) child.kill('SIGKILL');
        }, 5000);
      } catch {
        // already gone
      }
    },
    Math.max(0, opts.deadlineMs - Date.now()),
  );

  let stdoutBuf = '';
  child.stdout?.on('data', (chunk: Buffer) => {
    otelContext.with(parentCtx, () => {
      stdoutBuf += chunk.toString('utf8');
      while (true) {
        const nl = stdoutBuf.indexOf('\n');
        if (nl < 0) break;
        const line = stdoutBuf.slice(0, nl).trim();
        stdoutBuf = stdoutBuf.slice(nl + 1);
        if (!line) continue;

        let evt: CodexJsonEvent;
        try {
          evt = JSON.parse(line) as CodexJsonEvent;
        } catch (err) {
          log(`unparseable jsonl line: ${errMsg(err)}`);
          continue;
        }

        conversationLog.push(evt);

        if (evt.type === 'thread.started') {
          log(`thread_id=${evt.thread_id ?? '(none)'}`);
          setSpanAttributes(traceSpan, { 'codex.thread_id': evt.thread_id });
          continue;
        }

        if (evt.type === 'turn.started') {
          if (currentTurnSpan) endTraceSpan(currentTurnSpan);
          flushLog();
          turn++;
          currentTurnSpan = startTraceSpan(`agent.turn.${turn}`, 'CHAIN', {
            'imprint.agent.turn': turn,
            'imprint.agent.cumulative_input_tokens': inputTokens,
            'imprint.agent.cumulative_output_tokens': outputTokens,
          });
          fireProgress('thinking');
          continue;
        }

        if ((evt.type === 'item.started' || evt.type === 'item.completed') && evt.item) {
          const agentMessage = codexAgentMessageText(evt.item);
          if (agentMessage && evt.type === 'item.completed') {
            agentMessageCount++;
            setSpanAttributes(traceSpan, {
              'imprint.codex.agent_messages': agentMessageCount,
              'imprint.codex.last_agent_message_chars': agentMessage.length,
              ...(traceLlmIoEnabled()
                ? llmSpanAttributes({
                    provider: 'codex-cli',
                    model: preferredAgentModel('codex-cli'),
                    outputMessages: traceLlmMessages([
                      { role: 'assistant', content: agentMessage },
                    ]),
                    outputValue: agentMessage,
                  })
                : {}),
            });
            continue;
          }
          const toolName = codexToolName(evt.item);
          if (toolName) {
            traceCodexToolEvent(toolSpans, evt.type, evt.item, toolName);
            fireProgress(evt.type === 'item.started' ? 'tool' : 'thinking', toolName);
          }
          continue;
        }

        if (evt.type === 'turn.completed') {
          const turnInput = evt.usage?.input_tokens ?? 0;
          const turnOutput = evt.usage?.output_tokens ?? 0;
          inputTokens += turnInput;
          outputTokens += turnOutput;
          if (currentTurnSpan) {
            setSpanAttributes(currentTurnSpan, {
              'imprint.agent.turn_input_tokens': turnInput,
              'imprint.agent.turn_output_tokens': turnOutput,
            });
            endTraceSpan(currentTurnSpan);
            currentTurnSpan = null;
          }
          continue;
        }

        if (evt.type === 'error' || evt.type === 'turn.failed') {
          lastErrorMessage = evt.message ?? evt.error?.message ?? JSON.stringify(evt);
        }
      }
    });
  });

  child.stderr?.on('data', (chunk: Buffer) => {
    const s = chunk.toString('utf8');
    stderrBuf += s;
    log(`[codex stderr] ${s.trim()}`);
  });

  const exitCode: number = await new Promise((resolve) => {
    child.once('exit', (code) => resolve(code ?? -1));
    child.once('error', () => resolve(-1));
  });
  clearInterval(sentinelTimer);
  clearTimeout(deadlineTimer);
  if (currentTurnSpan) endTraceSpan(currentTurnSpan);
  for (const span of toolSpans.values()) endTraceSpan(span);
  toolSpans.clear();

  if (stdoutBuf.trim()) {
    log(`unflushed stdout tail (${stdoutBuf.length} bytes) discarded`);
  }

  flushLog();

  const workflowPath = pathJoin(opts.absoluteToolDir, 'workflow.json');
  const parserPath = pathJoin(opts.absoluteToolDir, 'parser.ts');
  const parserTestPath = pathJoin(opts.absoluteToolDir, 'parser.test.ts');

  const verifiedOk =
    existsSync(doneSentinel) &&
    (() => {
      try {
        const raw = readFileSync(doneSentinel, 'utf8').trim();
        return raw ? JSON.parse(raw).verification === 'passed' : false;
      } catch {
        return false;
      }
    })();
  if (verifiedOk && !opts.keepTest && existsSync(parserTestPath)) {
    try {
      unlinkSync(parserTestPath);
    } catch {
      // best effort
    }
  }

  const baseResult: Pick<
    CompileAgentResult,
    | 'workflowPath'
    | 'parserPath'
    | 'parserTestPath'
    | 'conversationLogPath'
    | 'turns'
    | 'durationMs'
    | 'inputTokens'
    | 'outputTokens'
    | 'cacheReadInputTokens'
    | 'cacheCreationInputTokens'
  > = {
    workflowPath: existsSync(workflowPath) ? workflowPath : undefined,
    parserPath: existsSync(parserPath) ? parserPath : undefined,
    parserTestPath: existsSync(parserTestPath) ? parserTestPath : undefined,
    conversationLogPath,
    turns: turn,
    durationMs: Date.now() - opts.startTime,
    inputTokens,
    outputTokens,
    cacheReadInputTokens: 0,
    cacheCreationInputTokens: 0,
  };

  if (existsSync(doneSentinel)) {
    let payload: {
      summary?: string;
      verification?: string;
      cycles?: number;
      failures?: string[];
    } = {};
    try {
      const raw = readFileSync(doneSentinel, 'utf8').trim();
      if (raw) payload = JSON.parse(raw);
    } catch (err) {
      log(`failed to parse done sentinel: ${errMsg(err)}`);
    }
    if (payload.verification === 'passed') {
      return {
        success: true,
        outcome: 'done',
        message: payload.summary ?? 'Task completed',
        ...baseResult,
      };
    }
    return {
      success: false,
      outcome: 'error',
      message: `Verification failed after ${payload.cycles ?? '?'} cycles. Final failures:\n${(payload.failures ?? []).join('\n')}`,
      ...baseResult,
    };
  }

  if (existsSync(giveUpSentinel)) {
    let payload: { reason?: string; what_was_tried?: string } = {};
    try {
      const raw = readFileSync(giveUpSentinel, 'utf8').trim();
      if (raw) payload = JSON.parse(raw);
    } catch (err) {
      log(`failed to parse give_up sentinel: ${errMsg(err)}`);
    }
    return {
      success: false,
      outcome: 'give_up',
      message: `Agent gave up: ${payload.reason ?? 'unknown reason'}\n${payload.what_was_tried ?? ''}`,
      ...baseResult,
    };
  }

  if (Date.now() > opts.deadlineMs) {
    return {
      success: false,
      outcome: 'timeout',
      message: `codex-cli exceeded the ${Math.round((opts.deadlineMs - opts.startTime) / 60000)} minute deadline before completing.`,
      ...baseResult,
    };
  }

  if (exitCode === 0) {
    return {
      success: false,
      outcome: 'soft_cap',
      message: 'codex-cli exited without calling done() or give_up(). It may have stopped early.',
      ...baseResult,
    };
  }

  const errorTail = lastErrorMessage || stderrBuf.trim().slice(-500);
  return {
    success: false,
    outcome: 'error',
    message: `codex-cli exited with code ${exitCode}${errorTail ? `\n${errorTail}` : ''}`,
    ...baseResult,
  };
}

function traceCodexToolEvent(
  spans: Map<string, Span>,
  eventType: string,
  item: NonNullable<CodexJsonEvent['item']>,
  toolName: string,
): void {
  const id = item.id ?? `${toolName}:${spans.size}`;
  const captureIo = traceToolIoEnabled();
  if (eventType === 'item.started') {
    const span = startTraceSpan(`mcp.${toolName}`, 'TOOL', {
      'mcp.server': item.server ?? MCP_SERVER_NAME,
      'mcp.tool_name': toolName,
      'codex.item_id': id,
      'codex.item_type': item.type,
      ...(captureIo && codexToolInput(item) !== undefined
        ? traceJsonInputOutputAttributes('input', codexToolInput(item), `mcp.${toolName}.input`)
        : {}),
    });
    if (span) spans.set(id, span);
    return;
  }
  const completionAttributes = {
    'codex.item_status': item.status,
    ...(captureIo && codexToolOutput(item) !== undefined
      ? traceJsonInputOutputAttributes('output', codexToolOutput(item), `mcp.${toolName}.output`)
      : {}),
  };
  const toolError = codexToolError(item);
  const span = spans.get(id);
  if (!span) {
    const completedSpan = startTraceSpan(`mcp.${toolName}`, 'TOOL', {
      'mcp.server': item.server ?? MCP_SERVER_NAME,
      'mcp.tool_name': toolName,
      'codex.item_id': id,
      'codex.item_type': item.type,
      'codex.event': 'completed_without_start',
      ...completionAttributes,
    });
    endTraceSpan(completedSpan, toolError);
    return;
  }
  setSpanAttributes(span, completionAttributes);
  endTraceSpan(span, toolError);
  spans.delete(id);
}

function codexAgentMessageText(item: NonNullable<CodexJsonEvent['item']>): string | undefined {
  if (item.type !== 'agent_message') return undefined;
  if (typeof item.text === 'string') return item.text;
  if (typeof item.content === 'string') return item.content;
  if (Array.isArray(item.content)) {
    const text = item.content
      .map((block) => {
        if (typeof block === 'string') return block;
        if (isRecord(block) && typeof block.text === 'string') return block.text;
        return '';
      })
      .filter(Boolean)
      .join('');
    return text || undefined;
  }
  return undefined;
}

function codexToolName(item: NonNullable<CodexJsonEvent['item']>): string | undefined {
  const type = item.type ?? '';
  if (type === 'agent_message') return undefined;
  const name = item.name ?? item.tool_name ?? item.tool;
  if (!name) return undefined;
  return name.replace(`mcp__${MCP_SERVER_NAME}__`, '');
}

function codexToolInput(item: NonNullable<CodexJsonEvent['item']>): unknown {
  return (
    item.arguments ??
    item.args ??
    item.input ??
    (item.command ? { command: item.command } : undefined)
  );
}

function codexToolOutput(item: NonNullable<CodexJsonEvent['item']>): unknown {
  return (
    item.result ??
    item.output ??
    item.content ??
    item.error ??
    (item.status ? { status: item.status } : undefined)
  );
}

function codexToolError(item: NonNullable<CodexJsonEvent['item']>): Error | undefined {
  if (!item.is_error && item.status !== 'error' && item.status !== 'failed') return undefined;
  const message =
    item.error === undefined
      ? `${codexToolName(item) ?? 'tool'} failed`
      : typeof item.error === 'string'
        ? item.error
        : JSON.stringify(item.error);
  return new Error(message);
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null && !Array.isArray(value);
}

function finalErrorResult(opts: CompileViaCodexCliOptions, message: string): CompileAgentResult {
  mkdirSync(opts.absoluteToolDir, { recursive: true });
  const conversationLogPath = pathJoin(opts.absoluteToolDir, '.compile-log.json');
  try {
    writeFileSync(conversationLogPath, JSON.stringify({ error: message }, null, 2), 'utf8');
  } catch {
    // best effort
  }
  return {
    success: false,
    outcome: 'error',
    message,
    conversationLogPath,
    turns: 0,
    durationMs: Date.now() - opts.startTime,
    inputTokens: 0,
    outputTokens: 0,
    cacheReadInputTokens: 0,
    cacheCreationInputTokens: 0,
  };
}

function errMsg(err: unknown): string {
  return err instanceof Error ? err.message : String(err);
}
