/**
 * Static frontend-evidence detector — plan-time structural corroboration for the
 * UI plan gate (#3312).
 *
 * `checkUiPresence` (ui-safety-gate.cjs) is a *vocabulary* signal: a hyphen is a
 * word boundary, so a phase section naming the repo `dashboard-financeiro` matches
 * the token `dashboard` exactly like the real UI compound `micro-frontend` does.
 * That boundary rule is intentional (#3718) and must not be weakened — instead,
 * the plan gate (`computeUiPlanGate` in check-command-router.cjs) corroborates the
 * token match against the static repo tree before blocking.
 *
 * This mirrors what the sibling post-wave gate (`computeUiSafetyGate`) already
 * does dynamically: it blocks only when `git diff HEAD~1 HEAD` touches UI files.
 * Plan time has no diff to inspect, so the corroboration here is static:
 *
 *   (a) a `package.json` (root) with a known UI-framework dependency — a project
 *       that ships react/vue/svelte/... in its manifest is a frontend regardless
 *       of file layout;
 *   (b) any `*.tsx` / `*.jsx` / `*.vue` / `*.svelte` file in the tree — the
 *       component-framework subset of `UI_FILE_EXTENSIONS_RE`
 *       (check-command-router.cjs). The weaker members of that list (css, scss,
 *       html, ...) are deliberately NOT static evidence: docs sites and
 *       markdown/bash/config repos routinely carry stray `.html`/`.css`, which
 *       is precisely the false-positive class #3312 reports.
 *   (c) any `*.xaml` file, or a `*.swift` / `*.kt` / `*.dart` file whose
 *       content carries its ecosystem's UI-framework import marker
 *       (`import SwiftUI` / `import UIKit`, `androidx.compose`,
 *       `package:flutter`) (#4658). Native UI projects (SwiftUI, Jetpack
 *       Compose, Flutter, .NET MAUI) carry neither (a) nor (b), which made the
 *       gate structurally unreachable for them. Source files match on the
 *       IMPORT, not the extension alone — the same unambiguity bar that
 *       justifies (b)'s subset and excludes (css, scss, html): a non-UI Swift
 *       package (a CLI, a server) imports Foundation, not SwiftUI, and must
 *       stay silent. `.xaml` is extension-alone for the same reason `.tsx` is —
 *       the extension itself is unambiguous. Marker matching is case-sensitive
 *       (imports are case-sensitive in all four ecosystems); extension
 *       matching is case-insensitive, mirroring `UI_COMPONENT_FILE_RE`.
 *
 * All I/O failures degrade to `false` (no evidence) — never throw.
 */

import fs from 'node:fs';
import path from 'node:path';

/** Component-framework file extensions — the static-evidence subset of UI_FILE_EXTENSIONS_RE. */
export const UI_COMPONENT_FILE_RE = /\.(tsx|jsx|vue|svelte)$/i;

/** Native UI source files whose CONTENT is scanned for an import marker (#4658). */
export const NATIVE_UI_SOURCE_RE = /\.(swift|kt|dart)$/i;

/** Native UI files that are evidence by extension alone — `.xaml`, the `.tsx` analogue. */
export const NATIVE_UI_XAML_RE = /\.xaml$/i;

/**
 * Per-extension UI-framework import markers for `NATIVE_UI_SOURCE_RE` files
 * (#4658). Every marker embeds its ecosystem's import keyword, so a bare
 * framework-name mention in prose or a comment is not evidence; the Dart
 * marker carries both legal quote styles. Case-sensitive: imports are
 * case-sensitive in Swift, Kotlin and Dart.
 */
export const NATIVE_UI_CONTENT_MARKERS: Readonly<Record<string, readonly string[]>> = {
  '.swift': ['import SwiftUI', 'import UIKit'],
  '.kt': ['import androidx.compose'],
  '.dart': ["import 'package:flutter", 'import "package:flutter'],
};

/**
 * UI-framework package.json dependencies (dependencies OR devDependencies).
 * Component frameworks/renderers only — deliberately excludes meta tooling
 * (typescript, eslint, ...) that non-frontend Node projects also carry.
 */
const UI_FRAMEWORK_DEPS: ReadonlySet<string> = new Set([
  'react',
  'react-dom',
  'vue',
  'svelte',
  '@sveltejs/kit',
  'angular',
  '@angular/core',
  'preact',
  'solid-js',
  'lit',
  'lit-element',
  'ember-source',
  '@remix-run/react',
  'react-native',
  'expo',
  'next',
  'nuxt',
  'gatsby',
  'astro',
  '@ionic/react',
  '@ionic/vue',
  '@ionic/angular',
]);

/** Directories never walked — dependencies, VCS data, build output, MSD planning state. */
const SKIP_DIRS: ReadonlySet<string> = new Set([
  'node_modules',
  '.git',
  '.planning',
  'dist',
  'build',
  'out',
  '.next',
  '.nuxt',
  '.output',
  'coverage',
  'vendor',
  '.cache',
]);

/** Walk safety cap — beyond this the tree is treated as scanned (evidence decided by then). */
const MAX_WALK_ENTRIES = 10_000;

function packageJsonHasUiFramework(projectDir: string): boolean {
  let raw: string;
  try {
    raw = fs.readFileSync(path.join(projectDir, 'package.json'), 'utf8');
  } catch {
    return false; // no/unreadable package.json → no evidence from this signal
  }
  let parsed: unknown;
  try {
    parsed = JSON.parse(raw);
  } catch {
    return false; // malformed package.json → no evidence from this signal
  }
  if (parsed === null || typeof parsed !== 'object') return false;
  const pkg = parsed as Record<string, unknown>;
  for (const field of ['dependencies', 'devDependencies', 'peerDependencies'] as const) {
    const deps = pkg[field];
    if (deps === null || typeof deps !== 'object') continue;
    for (const name of Object.keys(deps)) {
      if (UI_FRAMEWORK_DEPS.has(name)) return true;
    }
  }
  return false;
}

/**
 * Shared bounded BFS over the project tree — the single home of the walk
 * semantics both evidence walks depend on: SKIP_DIRS pruning, the
 * MAX_WALK_ENTRIES entry cap (cap-hit → `false`: the tree is treated as
 * scanned and evidence stays undecided), symlinks never followed
 * (withFileTypes Dirents), unreadable directories skipped. `visit` is called
 * for every regular file with its name and full path; returning `true` stops
 * the walk with `true` (evidence found).
 */
function walkProjectFiles(
  projectDir: string,
  visit: (name: string, fullPath: string) => boolean,
): boolean {
  const queue: string[] = [projectDir];
  let visited = 0;
  while (queue.length > 0 && visited < MAX_WALK_ENTRIES) {
    const dir = queue.shift() as string;
    let entries: fs.Dirent[];
    try {
      entries = fs.readdirSync(dir, { withFileTypes: true });
    } catch {
      continue; // unreadable directory → skip it
    }
    for (const entry of entries) {
      visited++;
      if (visited >= MAX_WALK_ENTRIES) return false;
      if (entry.isDirectory()) {
        if (!SKIP_DIRS.has(entry.name)) queue.push(path.join(dir, entry.name));
      } else if (entry.isFile() && visit(entry.name, path.join(dir, entry.name))) {
        return true;
      }
    }
  }
  return false;
}

function treeHasComponentFile(projectDir: string): boolean {
  return walkProjectFiles(projectDir, (name) => UI_COMPONENT_FILE_RE.test(name));
}

/**
 * Read at most the first 64 KiB of `file` and report whether any of `markers`
 * occurs in it (#4658). Import sections live at the top of a source file, so a
 * bounded prefix read keeps the gate's plan-time cost profile without reading
 * generated monsters in full. Any I/O failure degrades to false — never throw.
 */
function fileHasAnyMarker(file: string, markers: readonly string[]): boolean {
  let fd: number;
  try {
    fd = fs.openSync(file, 'r');
  } catch {
    return false;
  }
  try {
    const bytes = Buffer.alloc(64 * 1024);
    const read = fs.readSync(fd, bytes, 0, bytes.length, 0);
    const prefix = bytes.toString('utf8', 0, read);
    return markers.some((m) => prefix.includes(m));
  } catch {
    return false;
  } finally {
    try {
      fs.closeSync(fd);
    } catch {
      // already closed — nothing to degrade
    }
  }
}

/**
 * Native-UI walk over the shared bounded BFS (#4658): `.xaml` is evidence by
 * extension alone; `.swift`/`.kt`/`.dart` are evidence only when the file's
 * content carries its ecosystem's import marker.
 */
function treeHasNativeUiFile(projectDir: string): boolean {
  return walkProjectFiles(projectDir, (name, fullPath) => {
    if (NATIVE_UI_XAML_RE.test(name)) return true;
    if (NATIVE_UI_SOURCE_RE.test(name)) {
      const markers = NATIVE_UI_CONTENT_MARKERS[path.extname(name).toLowerCase()];
      return markers != null && fileHasAnyMarker(fullPath, markers);
    }
    return false;
  });
}

/**
 * Does the project tree carry static evidence of a frontend?
 *
 * @param projectDir - Absolute path to the project root (the gate's cwd).
 * @returns true when package.json declares a UI-framework dependency, the tree
 *          contains a component-framework file, or the tree contains native UI
 *          evidence (a `.xaml` file, or a `.swift`/`.kt`/`.dart` file carrying
 *          its ecosystem's UI import marker — #4658); false otherwise
 *          (including on any I/O failure — evidence must be affirmative).
 */
export function hasStaticFrontendEvidence(projectDir: string): boolean {
  if (typeof projectDir !== 'string' || projectDir === '') return false;
  if (packageJsonHasUiFramework(projectDir)) return true;
  if (treeHasComponentFile(projectDir)) return true;
  return treeHasNativeUiFile(projectDir);
}