import { invokeIpc } from './api-client';

const MAX_LINK_LENGTH = 4_096;
const LOCAL_WEB_FILE_PATTERN = /\.(?:html?|xhtml)$/i;

function isBoundedSingleLine(value: string): boolean {
  return value.length > 0
    && value.length <= MAX_LINK_LENGTH
    && !/[\0\r\n]/.test(value);
}

export function safeConversationExternalUrl(value: string | undefined): string | null {
  const candidate = value?.trim() ?? '';
  if (!isBoundedSingleLine(candidate)) return null;

  try {
    const url = new URL(candidate);
    if ((url.protocol !== 'https:' && url.protocol !== 'http:')
      || url.username
      || url.password) {
      return null;
    }
    return url.toString();
  } catch {
    return null;
  }
}

export function revealableConversationPath(value: string): string | null {
  const candidate = value.trim();
  if (!isBoundedSingleLine(candidate)) return null;

  const homeRelative = candidate === '~' || /^~[\\/]/.test(candidate);
  const posixAbsolute = candidate.startsWith('/');
  const windowsAbsolute = /^[A-Za-z]:[\\/]/.test(candidate);
  const windowsNetwork = /^\\\\[^\\]+\\[^\\]+/.test(candidate);
  return homeRelative || posixAbsolute || windowsAbsolute || windowsNetwork
    ? candidate
    : null;
}

export function openableConversationLocalWebPath(value: string): string | null {
  const path = revealableConversationPath(value);
  return path && LOCAL_WEB_FILE_PATTERN.test(path) ? path : null;
}

export function previewableConversationRelativePath(value: string): string | null {
  const candidate = value.trim();
  if (!isBoundedSingleLine(candidate)
    || revealableConversationPath(candidate)
    || /^[A-Za-z][A-Za-z0-9+.-]*:/.test(candidate)) {
    return null;
  }

  const normalized = candidate.replaceAll('\\', '/').replace(/^\.\//, '');
  const segments = normalized.split('/');
  if (!normalized
    || normalized.startsWith('/')
    || segments.some((segment) => !segment || segment === '.' || segment === '..')
    || !LOCAL_WEB_FILE_PATTERN.test(normalized)) {
    return null;
  }
  return normalized;
}

function comparableLocalPath(value: string): string {
  return value.replaceAll('\\', '/').replace(/\/$/, '');
}

export function resolveConversationMarkdownWebPath(
  value: string,
  markdown: string,
): string | null {
  const relativePath = previewableConversationRelativePath(value);
  if (!relativePath) return null;

  const matches = new Set<string>();
  for (const match of markdown.matchAll(/`([^`\r\n]+)`/g)) {
    const absolutePath = revealableConversationPath(match[1] ?? '');
    if (!absolutePath || !LOCAL_WEB_FILE_PATTERN.test(absolutePath)) continue;
    const comparable = comparableLocalPath(absolutePath);
    if (comparable.endsWith(`/${relativePath}`)) matches.add(absolutePath);
  }
  return matches.size === 1 ? [...matches][0] ?? null : null;
}

function resolveHomeRelativePath(value: string, home: string): string {
  if (value === '~') return home;
  const separator = home.includes('\\') ? '\\' : '/';
  const suffix = value.slice(2).replace(/[\\/]/g, separator);
  return `${home.replace(/[\\/]$/, '')}${separator}${suffix}`;
}

export async function openConversationExternalUrl(value: string): Promise<void> {
  const url = safeConversationExternalUrl(value);
  if (!url) throw new Error('Unsupported external URL');
  await invokeIpc('shell:openExternal', url);
}

export async function revealConversationPath(value: string): Promise<void> {
  const path = revealableConversationPath(value);
  if (!path) throw new Error('Unsupported local path');

  let resolvedPath = path;
  if (path === '~' || /^~[\\/]/.test(path)) {
    const home = await invokeIpc<string>('app:getPath', 'home');
    resolvedPath = resolveHomeRelativePath(path, home);
  }
  await invokeIpc('shell:showItemInFolder', resolvedPath);
}

export async function openConversationLocalWebFile(value: string): Promise<void> {
  const path = openableConversationLocalWebPath(value);
  if (!path) throw new Error('Unsupported local web file');

  let resolvedPath = path;
  if (path === '~' || /^~[\\/]/.test(path)) {
    const home = await invokeIpc<string>('app:getPath', 'home');
    resolvedPath = resolveHomeRelativePath(path, home);
  }
  const error = await invokeIpc<string>('shell:openPath', resolvedPath);
  if (error) throw new Error('Local web file could not be opened');
}

export async function showConversationLinkContextMenu(
  request:
    | { kind: 'external'; target: string }
    | { kind: 'local-web'; target: string },
): Promise<void> {
  if (request.kind === 'external') {
    const target = safeConversationExternalUrl(request.target);
    if (!target) throw new Error('Unsupported external URL');
    await invokeIpc('shell:showLinkContextMenu', { kind: request.kind, target });
    return;
  }

  const target = openableConversationLocalWebPath(request.target);
  if (!target) throw new Error('Unsupported local web file');
  await invokeIpc('shell:showLinkContextMenu', { kind: request.kind, target });
}