/**
 * ─────────────────────────────────────────────
 *  SPB Git — Personal Git Platform
 * ─────────────────────────────────────────────
 *  Author  : Simon-Pierre Boucher
 *  Contact : contact@spboucher.ai
 *  File    : src/render/highlight.mjs
 *  Purpose : Shiki syntax highlighting — dual theme, line anchors
 *  License : MIT © Simon-Pierre Boucher
 * ─────────────────────────────────────────────
 */

import { createHighlighter, bundledLanguages } from 'shiki';
import { escapeHtml } from '../lib/util.mjs';

const THEMES = { light: 'github-light', dark: 'github-dark' };

/** Languages loaded eagerly at boot — everything else lazy-loads. */
const COMMON_LANGS = [
  'javascript', 'typescript', 'jsx', 'tsx', 'python', 'go', 'rust', 'c', 'cpp',
  'java', 'ruby', 'php', 'shellscript', 'sql', 'json', 'jsonc', 'yaml', 'toml', 'html',
  'css', 'scss', 'markdown', 'diff', 'docker', 'make', 'xml', 'ini', 'lua', 'swift',
  'kotlin', 'r', 'julia',
];

/** File extension → shiki language id (for the blob view). */
const EXT_TO_LANG = {
  '.js': 'javascript', '.mjs': 'javascript', '.cjs': 'javascript', '.jsx': 'jsx',
  '.ts': 'typescript', '.mts': 'typescript', '.cts': 'typescript', '.tsx': 'tsx',
  '.py': 'python', '.pyw': 'python', '.pyi': 'python',
  '.go': 'go', '.rs': 'rust',
  '.c': 'c', '.h': 'c', '.cpp': 'cpp', '.cc': 'cpp', '.cxx': 'cpp', '.hpp': 'cpp', '.hh': 'cpp',
  '.cs': 'csharp', '.java': 'java', '.kt': 'kotlin', '.kts': 'kotlin', '.swift': 'swift',
  '.m': 'objective-c', '.mm': 'objective-cpp',
  '.rb': 'ruby', '.rake': 'ruby', '.gemspec': 'ruby', '.php': 'php',
  '.sh': 'shellscript', '.bash': 'shellscript', '.zsh': 'shellscript', '.fish': 'fish',
  '.ps1': 'powershell', '.pl': 'perl', '.pm': 'perl', '.lua': 'lua',
  '.r': 'r', '.jl': 'julia', '.scala': 'scala', '.hs': 'haskell',
  '.ex': 'elixir', '.exs': 'elixir', '.erl': 'erlang', '.clj': 'clojure', '.cljs': 'clojure',
  '.dart': 'dart', '.zig': 'zig', '.nim': 'nim', '.ml': 'ocaml', '.mli': 'ocaml',
  '.fs': 'fsharp', '.fsx': 'fsharp', '.sol': 'solidity', '.cu': 'cuda-cpp',
  '.vue': 'vue', '.svelte': 'svelte', '.astro': 'astro',
  '.html': 'html', '.htm': 'html', '.xhtml': 'html', '.xml': 'xml', '.svg': 'xml', '.plist': 'xml',
  '.css': 'css', '.scss': 'scss', '.sass': 'sass', '.less': 'less',
  '.json': 'json', '.jsonc': 'jsonc', '.ipynb': 'json',
  '.yml': 'yaml', '.yaml': 'yaml', '.toml': 'toml', '.ini': 'ini', '.cfg': 'ini', '.conf': 'ini',
  '.sql': 'sql', '.graphql': 'graphql', '.gql': 'graphql', '.proto': 'proto',
  '.md': 'markdown', '.markdown': 'markdown', '.mdx': 'mdx', '.rst': 'rst',
  '.tex': 'latex', '.sty': 'latex', '.bib': 'bibtex',
  '.dockerfile': 'docker', '.mk': 'make', '.cmake': 'cmake',
  '.nix': 'nix', '.tf': 'terraform', '.tfvars': 'terraform',
  '.groovy': 'groovy', '.gradle': 'groovy', '.vim': 'viml', '.njk': 'jinja',
  '.ejs': 'html', '.hbs': 'handlebars', '.env': 'dotenv', '.diff': 'diff', '.patch': 'diff',
  '.txt': 'text', '.log': 'text', '.csv': 'csv', '.service': 'ini',
};

const FILENAME_TO_LANG = {
  Dockerfile: 'docker', Containerfile: 'docker', Makefile: 'make', GNUmakefile: 'make',
  makefile: 'make', 'CMakeLists.txt': 'cmake', '.gitignore': 'text', '.gitattributes': 'text',
  '.vimrc': 'viml', '.env': 'dotenv', '.env.example': 'dotenv', LICENSE: 'text',
};

let highlighter = null;

/** Boot-time initialization — must run before any highlight call. */
export async function initHighlighter() {
  if (highlighter) return highlighter;
  highlighter = await createHighlighter({
    themes: Object.values(THEMES),
    langs: COMMON_LANGS,
  });
  return highlighter;
}

/**
 * Normalize a user-supplied fence language to a loadable shiki id.
 * @param {string} lang
 * @returns {string|null} shiki id, or null when unknown
 */
export function resolveLang(lang) {
  if (!lang) return null;
  const id = String(lang).trim().toLowerCase();
  const aliases = {
    sh: 'shellscript', bash: 'shellscript', zsh: 'shellscript', shell: 'shellscript',
    console: 'shellscript', 'c++': 'cpp', 'c#': 'csharp', yml: 'yaml', dockerfile: 'docker',
    makefile: 'make', js: 'javascript', ts: 'typescript', golang: 'go', rb: 'ruby',
    py: 'python', kt: 'kotlin', plaintext: 'text', text: 'text', txt: 'text',
  };
  const resolved = aliases[id] ?? id;
  if (resolved === 'text') return 'text';
  return resolved in bundledLanguages ? resolved : null;
}

/**
 * Ensure a set of shiki languages are loaded (lazy, cached in the singleton).
 * @param {string[]} langs shiki ids
 */
export async function ensureLangs(langs) {
  if (!highlighter) await initHighlighter();
  const loaded = new Set(highlighter.getLoadedLanguages());
  for (const lang of langs) {
    if (!lang || lang === 'text' || loaded.has(lang)) continue;
    if (lang in bundledLanguages) {
      try {
        await highlighter.loadLanguage(lang);
      } catch {
        /* fall back to plain rendering */
      }
    }
  }
}

/**
 * Synchronously highlight code (language must already be loaded).
 * @param {string} code
 * @param {string|null} lang shiki id
 * @returns {string} `<pre class="shiki">…` markup (plain fallback when needed)
 */
export function highlightSync(code, lang) {
  const plain = () =>
    `<pre class="shiki shiki-plain"><code>${code
      .split('\n')
      .map((l) => `<span class="line">${escapeHtml(l)}</span>`)
      .join('\n')}</code></pre>`;
  if (!highlighter || !lang || lang === 'text') return plain();
  if (!highlighter.getLoadedLanguages().includes(lang)) return plain();
  try {
    return highlighter.codeToHtml(code, {
      lang,
      themes: THEMES,
      defaultColor: false,
    });
  } catch {
    return plain();
  }
}

/**
 * Async highlight — loads the language on demand first.
 * @param {string} code
 * @param {string|null} langInput raw language hint (fence info / extension)
 */
export async function highlight(code, langInput) {
  const lang = resolveLang(langInput);
  if (lang) await ensureLangs([lang]);
  return highlightSync(code, lang);
}

/**
 * Highlight a full file for the blob view — adds line ids + anchor links.
 * @param {string} code file content
 * @param {string} path file path (extension-based detection)
 * @returns {Promise<{html: string, lines: number, lang: string|null}>}
 */
export async function highlightFile(code, path) {
  const base = path.split('/').pop() ?? path;
  const dot = base.lastIndexOf('.');
  const ext = dot >= 0 ? base.slice(dot).toLowerCase() : '';
  const lang = FILENAME_TO_LANG[base] ?? EXT_TO_LANG[ext] ?? null;
  const html = await highlight(code, lang);
  let line = 0;
  const withAnchors = html.replaceAll('<span class="line">', () => {
    line += 1;
    return `<span class="line" id="L${line}"><a class="ln" href="#L${line}" aria-label="Line ${line}">${line}</a>`;
  });
  const lines = code === '' ? 0 : code.split('\n').length;
  return { html: withAnchors, lines, lang };
}

/**
 * Language hint for a path (used by the blob header badge).
 * @param {string} path
 * @returns {string|null}
 */
export function langForPath(path) {
  const base = path.split('/').pop() ?? path;
  const dot = base.lastIndexOf('.');
  const ext = dot >= 0 ? base.slice(dot).toLowerCase() : '';
  return FILENAME_TO_LANG[base] ?? EXT_TO_LANG[ext] ?? null;
}