#!/usr/bin/env node
// copilot-adapter.mjs — Normalizes GitHub Copilot hook I/O to internal format.
//
// Copilot CLI hooks receive JSON on stdin with camelCase field names
// (toolName, toolArgs, toolResult) and signal blocking via exit code 2
// or stdout JSON with permissionDecision: "deny".
//
// This adapter provides a consistent interface so hook logic stays
// platform-agnostic. If Copilot changes field names, only this file
// needs updating.

import { readFileSync } from 'node:fs';

/**
 * Parse hook input from stdin. Returns normalized object or null on failure.
 * Supports both Copilot (camelCase) and Claude Code (snake_case) field names.
 */
export function parseInput() {
  try {
    const raw = readFileSync(0, 'utf-8');
    const input = JSON.parse(raw);
    return {
      toolName: input.toolName ?? input.tool_name ?? '',
      toolInput: input.toolArgs ?? input.tool_input ?? {},
      toolOutput: input.toolResult ?? input.tool_output ?? '',
      message: input.message ?? {},
      sessionId: input.sessionId ?? input.session_id ?? '',
      raw: input,
    };
  } catch {
    return null;
  }
}

/**
 * Block the tool call with a reason message.
 */
export function block(reason) {
  process.stderr.write(reason + '\n');
  process.stdout.write(JSON.stringify({
    permissionDecision: 'deny',
    reason,
  }));
  process.exit(2);
}

/**
 * Allow the tool call, optionally with an advisory message.
 */
export function allow(message) {
  if (message) {
    process.stdout.write(JSON.stringify({
      permissionDecision: 'allow',
      message,
    }));
  }
  process.exit(0);
}

/**
 * Emit a warning to stderr without blocking. Exit 0.
 */
export function warn(message) {
  process.stderr.write(message + '\n');
  process.exit(0);
}

/**
 * Fail-open: exit 0 silently. Used when input can't be parsed.
 */
export function failOpen() {
  process.exit(0);
}