/**
 * Repo scan for `.md` files the cockpit should know about (DRAFT-001 v0.3.0).
 *
 * Conservative scope: repo-root well-known files + repo-root `docs/`,
 * plus each `packages/*` package's well-known files + its `docs/`.
 * No fancy globbing, no recursion past `docs/`. If any directory is
 * absent we skip silently — this extension is opt-in, never noisy.
 */

import * as fs from "node:fs";
import * as path from "node:path";

const ROOT_FILES = ["SPEC.md", "CONSTITUTION.md", "AGENTS.md", "CHANGELOG.md", "README.md"];
const PACKAGE_FILES = ["SPEC.md", "README.md", "CHANGELOG.md"];

/** Returns absolute paths to every `.md` file the cockpit should track. */
export function discoverSpecFiles(repoRoot: string): string[] {
  const found = new Set<string>();

  // Repo root well-known files.
  for (const name of ROOT_FILES) {
    const p = path.join(repoRoot, name);
    if (existsAsFile(p)) found.add(p);
  }

  // Repo root docs/ (recursive).
  collectMdRecursive(path.join(repoRoot, "docs"), found);

  // Per-package files + docs/.
  const packagesDir = path.join(repoRoot, "packages");
  if (existsAsDir(packagesDir)) {
    for (const pkgName of safeReaddir(packagesDir)) {
      const pkgDir = path.join(packagesDir, pkgName);
      if (!existsAsDir(pkgDir)) continue;
      for (const name of PACKAGE_FILES) {
        const p = path.join(pkgDir, name);
        if (existsAsFile(p)) found.add(p);
      }
      collectMdRecursive(path.join(pkgDir, "docs"), found);
    }
  }

  return Array.from(found).sort();
}

function collectMdRecursive(dir: string, sink: Set<string>) {
  if (!existsAsDir(dir)) return;
  for (const entry of safeReaddirWithTypes(dir)) {
    const full = path.join(dir, entry.name);
    if (entry.isDirectory()) {
      collectMdRecursive(full, sink);
    } else if (entry.isFile() && entry.name.endsWith(".md")) {
      sink.add(full);
    }
  }
}

function existsAsFile(p: string): boolean {
  try {
    return fs.statSync(p).isFile();
  } catch {
    return false;
  }
}

function existsAsDir(p: string): boolean {
  try {
    return fs.statSync(p).isDirectory();
  } catch {
    return false;
  }
}

function safeReaddir(dir: string): string[] {
  try {
    return fs.readdirSync(dir);
  } catch {
    return [];
  }
}

function safeReaddirWithTypes(dir: string): fs.Dirent[] {
  try {
    return fs.readdirSync(dir, { withFileTypes: true });
  } catch {
    return [];
  }
}

/**
 * Extract a `.md` path from a tool_call/tool_result event input. Returns
 * the absolute path if the tool is one we recognise as a file mutation
 * targeting a markdown file; otherwise undefined.
 */
export function extractMdPathFromTool(
  toolName: string | undefined,
  input: unknown,
  cwd: string,
): string | undefined {
  if (!toolName) return undefined;
  if (!isFileWriteTool(toolName)) return undefined;
  if (!input || typeof input !== "object") return undefined;
  const obj = input as Record<string, unknown>;
  const raw = obj.path ?? obj.file_path ?? obj.filePath;
  if (typeof raw !== "string" || raw.length === 0) return undefined;
  if (!raw.endsWith(".md")) return undefined;
  return path.isAbsolute(raw) ? raw : path.resolve(cwd, raw);
}

function isFileWriteTool(name: string): boolean {
  // Cover pi built-ins and common Anthropic-style tool names.
  return name === "write" || name === "edit" || name === "str_replace" ||
    name === "str_replace_editor" || name === "create";
}