// Copyright (C) 2025 Keygraph, Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License version 3
// as published by the Free Software Foundation.

// Production agent execution on the pi harness, with git checkpoints and audit logging.

import { createRequire } from 'node:module';
import type { AgentMessage } from '@earendil-works/pi-agent-core';
import {
  type AgentSessionEvent,
  createAgentSession,
  DefaultResourceLoader,
  getAgentDir,
  ModelRegistry,
  type ResourceLoader,
  SessionManager,
  SettingsManager,
  type ToolDefinition,
} from '@earendil-works/pi-coding-agent';
import { fs, path } from 'zx';
import type { AuditSession } from '../audit/index.js';
import { BASH_TIMEOUT_EXTENSION_DIR, deliverablesDir, PLAYWRIGHT_SKILL_DIR } from '../paths.js';
import { isRetryableError, PentestError } from '../services/error-handling.js';
import { AGENT_VALIDATORS } from '../session-manager.js';
import type { ActivityLogger } from '../types/activity-logger.js';
import { ErrorCode } from '../types/errors.js';
import { isSpendingCapBehavior, matchesBillingTextPattern } from '../utils/billing-detection.js';
import { formatTimestamp } from '../utils/formatting.js';
import { Timer } from '../utils/metrics.js';
import { createAuditLogger } from './audit-logger.js';
import { type ModelTier, resolveModelSelection } from './models.js';
import {
  detectExecutionContext,
  formatAssistantOutput,
  formatCompletionMessage,
  formatErrorOutput,
  formatToolCall,
} from './output-formatters.js';
import { createProgressManager } from './progress-manager.js';
import { permissionConfigPath } from './settings-writer.js';
import { createGlobTool, createTaskTool, createTodoWriteTool } from './tools.js';

declare global {
  var SHANNON_DISABLE_LOADER: boolean | undefined;
}

/** Built-in pi tools enabled for every agent (custom tool names are appended). */
const BUILTIN_TOOLS = ['read', 'bash', 'edit', 'write', 'grep', 'find', 'ls'];

const requireFromHere = createRequire(import.meta.url);
let cachedExtensionDir: string | null | undefined;

/** Resolve the installed @gotgenes/pi-permission-system package dir, or null. */
function permissionExtensionDir(): string | null {
  if (cachedExtensionDir !== undefined) return cachedExtensionDir;
  try {
    const entry = requireFromHere.resolve('@gotgenes/pi-permission-system');
    cachedExtensionDir = path.dirname(path.dirname(entry));
  } catch {
    cachedExtensionDir = null;
  }
  return cachedExtensionDir;
}

async function buildResourceLoader(cwd: string, logger: ActivityLogger): Promise<ResourceLoader> {
  // Always enforce bounded bash timeouts so an unbounded command cannot hang the agent.
  const additionalExtensionPaths: string[] = [BASH_TIMEOUT_EXTENSION_DIR];
  if (fs.existsSync(permissionConfigPath())) {
    const extDir = permissionExtensionDir();
    if (extDir) {
      additionalExtensionPaths.push(extDir);
    } else {
      logger.warn(
        'code_path deny config present but @gotgenes/pi-permission-system not resolvable — skipping enforcement',
      );
    }
  }

  const loader = new DefaultResourceLoader({
    cwd,
    agentDir: getAgentDir(),
    additionalSkillPaths: [PLAYWRIGHT_SKILL_DIR],
    ...(additionalExtensionPaths.length > 0 && { additionalExtensionPaths }),
  });
  await loader.reload();
  return loader;
}

export interface PiPromptResult {
  result?: string | null | undefined;
  success: boolean;
  duration: number;
  turns?: number | undefined;
  cost: number;
  model?: string | undefined;
  partialCost?: number | undefined;
  apiErrorDetected?: boolean | undefined;
  error?: string | undefined;
  errorType?: string | undefined;
  prompt?: string | undefined;
  retryable?: boolean | undefined;
  structuredOutput?: unknown;
}

function outputLines(lines: string[]): void {
  for (const line of lines) {
    console.log(line);
  }
}

async function writeErrorLog(
  err: Error & { code?: string; status?: number },
  sourceDir: string,
  fullPrompt: string,
  duration: number,
): Promise<void> {
  try {
    const errorLog = {
      timestamp: formatTimestamp(),
      agent: 'pi-executor',
      error: { name: err.constructor.name, message: err.message, code: err.code, status: err.status, stack: err.stack },
      context: { sourceDir, prompt: `${fullPrompt.slice(0, 200)}...`, retryable: isRetryableError(err) },
      duration,
    };
    const logPath = path.join(deliverablesDir(sourceDir), 'error.log');
    await fs.appendFile(logPath, `${JSON.stringify(errorLog)}\n`);
  } catch {
    // Best-effort error log writing - don't propagate failures
  }
}

export async function validateAgentOutput(
  result: PiPromptResult,
  agentName: string | null,
  sourceDir: string,
  logger: ActivityLogger,
): Promise<boolean> {
  logger.info(`Validating ${agentName} agent output`);
  try {
    if (!result.success || (!result.result && result.structuredOutput === undefined)) {
      logger.error('Validation failed: Agent execution was unsuccessful');
      return false;
    }
    const validator = agentName ? AGENT_VALIDATORS[agentName as keyof typeof AGENT_VALIDATORS] : undefined;
    if (!validator) {
      logger.warn(`No validator found for agent "${agentName}" - assuming success`);
      return true;
    }
    logger.info(`Using validator for agent: ${agentName}`, { sourceDir });
    const validationResult = await validator(sourceDir, logger);
    if (validationResult) {
      logger.info('Validation passed: Required files/structure present');
    } else {
      logger.error('Validation failed: Missing required deliverable files');
    }
    return validationResult;
  } catch (error) {
    const errMsg = error instanceof Error ? error.message : String(error);
    logger.error(`Validation failed with error: ${errMsg}`);
    return false;
  }
}

/** Concatenate the text blocks of an assistant message (skips thinking + tool calls). */
function extractAssistantText(message: AgentMessage): string {
  if (message.role !== 'assistant') return '';
  const blocks = message.content as Array<{ type: string; text?: string }>;
  return blocks
    .filter((c) => c.type === 'text')
    .map((c) => c.text ?? '')
    .join('\n');
}

/**
 * Classify error-bearing text into a PentestError, mirroring the prior provider error
 * handling. Spending-cap / billing text is retryable (Temporal backs off and
 * recovers when the cap resets); session limit is permanent.
 */
function classifyErrorText(content: string): PentestError | null {
  if (!content) return null;
  if (matchesBillingTextPattern(content)) {
    return new PentestError(
      `Billing limit reached: ${content.slice(0, 100)}`,
      'billing',
      true,
      {},
      ErrorCode.SPENDING_CAP_REACHED,
    );
  }
  if (content.toLowerCase().includes('session limit reached')) {
    return new PentestError('Session limit reached', 'billing', false);
  }
  return null;
}

// Low-level pi execution. Drives one agent session to completion with progress and
// audit logging. Exported for Temporal activities to call single-attempt execution.
export async function runPiPrompt(
  prompt: string,
  sourceDir: string,
  context: string = '',
  description: string = 'Agent analysis',
  _agentName: string | null = null,
  auditSession: AuditSession | null = null,
  logger: ActivityLogger,
  modelTier: ModelTier = 'medium',
  callerTools?: ToolDefinition[],
  apiKey?: string,
  deliverablesSubdir?: string,
  providerConfig?: import('../types/config.js').ProviderConfig,
): Promise<PiPromptResult> {
  // 1. Initialize timing and prompt
  const timer = new Timer(`agent-${description.toLowerCase().replace(/\s+/g, '-')}`);
  const fullPrompt = context ? `${context}\n\n${prompt}` : prompt;

  // 2. Set up progress and audit infrastructure
  const execContext = detectExecutionContext(description);
  const progress = createProgressManager(
    { description, useCleanOutput: execContext.useCleanOutput },
    global.SHANNON_DISABLE_LOADER ?? false,
  );
  const auditLogger = createAuditLogger(auditSession);

  logger.info(`Running pi agent: ${description}...`);

  // 3. Expose bash-invoked CLI tooling (playwright-cli, save-deliverable) to the
  //    environment pi's bash tool inherits. These are constant per container, so
  //    setting them on process.env is parallel-safe across this workflow's agents.
  process.env.PLAYWRIGHT_MCP_OUTPUT_DIR = deliverablesSubdir
    ? path.join(sourceDir, path.dirname(deliverablesSubdir), '.playwright-cli')
    : path.join(sourceDir, '.shannon', '.playwright-cli');
  if (deliverablesSubdir) process.env.SHANNON_DELIVERABLES_SUBDIR = deliverablesSubdir;
  if (apiKey) process.env.ANTHROPIC_API_KEY = apiKey;

  // 4. Resolve model + auth, then assemble the tool set (universal task/todo tools
  //    plus any caller-supplied collector/submit tools).
  const selection = resolveModelSelection((auth) => ModelRegistry.create(auth), modelTier, apiKey, providerConfig);
  const resourceLoader = await buildResourceLoader(sourceDir, logger);
  // Accumulates cost from in-process `task` child sessions so the parent's reported
  // cost includes sub-agent spend (their getSessionStats is separate from ours).
  const childUsage = { cost: 0 };
  const customTools: ToolDefinition[] = [
    createTaskTool({
      model: selection.model,
      thinkingLevel: selection.thinkingLevel,
      authStorage: selection.authStorage,
      cwd: sourceDir,
      childUsage,
      resourceLoader,
    }),
    createTodoWriteTool(auditLogger),
    createGlobTool(sourceDir),
    ...(callerTools ?? []),
  ];
  // pi's `tools` allowlist gates custom tools too — list every custom name.
  const tools = [...BUILTIN_TOOLS, ...customTools.map((t) => t.name)];

  let turnCount = 0;
  let pendingError: PentestError | null = null;
  let apiErrorDetected = false;

  progress.start();

  try {
    const { session } = await createAgentSession({
      cwd: sourceDir,
      model: selection.model,
      thinkingLevel: selection.thinkingLevel,
      tools,
      customTools,
      authStorage: selection.authStorage,
      sessionManager: SessionManager.inMemory(),
      // Temporal owns retry; pi compaction stays on (no analog previously, guards
      // against context overflow on long agent runs).
      settingsManager: SettingsManager.inMemory({ retry: { enabled: false }, compaction: { enabled: true } }),
      resourceLoader,
    });

    // 5. Map pi events to audit logging + progress + error capture.
    session.subscribe((event: AgentSessionEvent) => {
      switch (event.type) {
        case 'turn_end': {
          turnCount += 1;
          const msg = event.message;
          const text = extractAssistantText(msg);
          if (text.trim()) {
            void auditLogger.logLlmResponse(turnCount, text);
            progress.stop();
            outputLines(formatAssistantOutput(text, execContext, turnCount, description));
            progress.start();
            const billing = classifyErrorText(text);
            if (billing) pendingError = billing;
          }
          if (msg.role === 'assistant' && msg.stopReason === 'error') {
            apiErrorDetected = true;
            pendingError =
              pendingError ??
              classifyErrorText(msg.errorMessage ?? '') ??
              new PentestError(`Agent error: ${(msg.errorMessage ?? 'unknown').slice(0, 200)}`, 'unknown', true);
          }
          break;
        }
        case 'tool_execution_start': {
          void auditLogger.logToolStart(event.toolName, event.args);
          const toolLines = formatToolCall(
            event.toolName,
            event.args as Record<string, unknown>,
            execContext,
            description,
          );
          if (toolLines.length > 0) {
            progress.stop();
            outputLines(toolLines);
            progress.start();
          }
          break;
        }
        case 'tool_execution_end':
          void auditLogger.logToolEnd(event.result);
          break;
        case 'compaction_end':
          if (!event.aborted && !event.willRetry && event.errorMessage) {
            pendingError =
              pendingError ??
              classifyErrorText(event.errorMessage) ??
              new PentestError(`Context compaction failed: ${event.errorMessage.slice(0, 200)}`, 'unknown', true);
          }
          break;
        default:
          break;
      }
    });

    // 6. Run the agent to completion (resolves at agent_end).
    await session.prompt(fullPrompt);
    session.dispose();

    // 7. Surface any error captured during the run.
    if (pendingError) throw pendingError;

    // 8. Read usage/cost and final text.
    const stats = session.getSessionStats();
    const totalCost = stats.cost + childUsage.cost;
    const result = session.getLastAssistantText() ?? null;

    // 9. Defense-in-depth: detect a spending cap that produced an empty/cheap run.
    if (isSpendingCapBehavior(turnCount, totalCost, result || '')) {
      throw new PentestError(
        `Spending cap likely reached (turns=${turnCount}, cost=$0): ${result?.slice(0, 100)}`,
        'billing',
        true,
      );
    }

    const duration = timer.stop();
    progress.finish(formatCompletionMessage(execContext, description, turnCount, duration));

    return {
      result,
      success: true,
      duration,
      turns: turnCount,
      cost: totalCost,
      model: selection.model.id,
      partialCost: totalCost,
      apiErrorDetected,
    };
  } catch (error) {
    // 10. Handle errors — log, write error file, return failure
    const duration = timer.stop();
    const err = error as Error & { code?: string; status?: number };
    await auditLogger.logError(err, duration, turnCount);
    progress.stop();
    outputLines(formatErrorOutput(err, execContext, description, duration, sourceDir, isRetryableError(err)));
    await writeErrorLog(err, sourceDir, fullPrompt, duration);

    return {
      error: err.message,
      errorType: err.constructor.name,
      prompt: `${fullPrompt.slice(0, 100)}...`,
      success: false,
      duration,
      cost: 0,
      retryable: isRetryableError(err),
    };
  }
}