import { execSync } from "child_process";
import fs from "fs";
import path from "path";
import { ALL_APPS } from "../packages/stack-shared/src/apps/apps-config";
import {
  buildDashboardReferenceApps,
  DASHBOARD_REFERENCE_PLACEHOLDER_BODY,
  getDashboardReferenceDocPath,
  listDashboardReferencePages,
  type DiscoveredNavigableApp,
} from "./lib/dashboard-reference-docs";
import { extractDashboardReferenceJSDocs } from "./lib/extract-dashboard-reference-jsdoc";
import { writeFileSyncIfChanged } from "./utils";

const repoRoot = path.resolve(__dirname, "..");
const appsFrontendPath = path.join(repoRoot, "apps/dashboard/src/lib/apps-frontend.tsx");
const generatedMdxComment = "This file is auto-generated by scripts/generate-dashboard-reference-docs.ts. Do not edit it manually; update the @dashboardReference JSDoc on the dashboard page component.";
const mdxRoot = path.join(repoRoot, "docs-mintlify/guides/dashboard-references");
const docsJsonPath = path.join(repoRoot, "docs-mintlify/docs.json");

type DocsJson = {
  navigation: {
    tabs: Array<{
      tab: string,
      pages: unknown[],
    }>,
  },
  redirects: Array<{ source: string, destination: string }>,
};

type NavigationItem = {
  displayName: string,
  external: boolean,
};

function readBody(
  jsdocDocs: ReturnType<typeof extractDashboardReferenceJSDocs>,
  appId: string,
  slug: string,
): string {
  const fromJsdoc = jsdocDocs.get(`${appId}/${slug}`);
  if (fromJsdoc != null) {
    return fromJsdoc.body.replace(/\r\n/g, "\n").replace(/\n+$/, "") + "\n";
  }
  return `${DASHBOARD_REFERENCE_PLACEHOLDER_BODY}\n`;
}

function mergePageMetadataFromJsdoc<T extends { title: string, description: string, sidebarTitle?: string }>(
  appId: string,
  slug: string,
  page: T,
  jsdocDocs: ReturnType<typeof extractDashboardReferenceJSDocs>,
): T {
  const fromJsdoc = jsdocDocs.get(`${appId}/${slug}`);
  if (fromJsdoc == null) {
    return page;
  }
  return {
    ...page,
    title: fromJsdoc.title ?? page.title,
    description: fromJsdoc.description ?? page.description,
    sidebarTitle: fromJsdoc.title != null ? (page.sidebarTitle ?? page.title) : page.sidebarTitle,
  };
}

function renderMdx(
  page: { title: string, description: string, sidebarTitle?: string },
  body: string,
): string {
  const sidebarTitle = page.sidebarTitle ?? page.title;
  return [
    "---",
    "hidden: true",
    `title: ${JSON.stringify(page.title)}`,
    `description: ${JSON.stringify(page.description)}`,
    `sidebarTitle: ${JSON.stringify(sidebarTitle)}`,
    "---",
    "",
    `{/* ${generatedMdxComment} */}`,
    "",
    body.endsWith("\n") ? body : `${body}\n`,
  ].join("\n");
}

function buildDashboardReferenceNavGroup(dashboardReferenceApps: ReturnType<typeof buildDashboardReferenceApps>) {
  return {
    group: "Dashboard reference",
    hidden: true,
    searchable: true,
    pages: dashboardReferenceApps.map((app) => ({
      group: app.groupLabel,
      icon: app.icon,
      pages: app.pages.map((page) => getDashboardReferenceDocPath(app.appId, page.slug)),
    })),
  };
}

function patchDocsJson(
  dashboardReferenceNavGroup: ReturnType<typeof buildDashboardReferenceNavGroup>,
  dashboardReferenceApps: ReturnType<typeof buildDashboardReferenceApps>,
) {
  const docsJson = JSON.parse(fs.readFileSync(docsJsonPath, "utf-8")) as DocsJson;
  const documentationTab = docsJson.navigation.tabs.find((tab) => tab.tab === "Documentation");
  if (documentationTab == null) {
    throw new Error('docs.json: "Documentation" tab not found');
  }

  const pages = documentationTab.pages;
  const integrationsIndex = pages.findIndex(
    (entry) => typeof entry === "object" && entry != null && "group" in entry && (entry as { group: string }).group === "Integrations",
  );
  if (integrationsIndex === -1) {
    throw new Error('docs.json: "Integrations" group not found under Documentation');
  }

  const dashboardRefIndex = pages.findIndex(
    (entry) => typeof entry === "object" && entry != null && "group" in entry && (entry as { group: string }).group === "Dashboard reference",
  );

  const nextPages = [...pages];
  if (dashboardRefIndex === -1) {
    nextPages.splice(integrationsIndex, 0, dashboardReferenceNavGroup);
  } else {
    nextPages[dashboardRefIndex] = dashboardReferenceNavGroup;
  }

  documentationTab.pages = nextPages;

  const legacyRedirects: Array<{ source: string, destination: string }> = [];
  for (const { app, page } of listDashboardReferencePages(dashboardReferenceApps)) {
    const legacySource = `/guides/apps/${app.appId}/${page.slug}`;
    const destination = `/${getDashboardReferenceDocPath(app.appId, page.slug)}`;
    legacyRedirects.push({ source: legacySource, destination });
  }

  const redirectSources = new Set(docsJson.redirects.map((r) => r.source));
  for (const redirect of legacyRedirects) {
    if (!redirectSources.has(redirect.source)) {
      docsJson.redirects.push(redirect);
      redirectSources.add(redirect.source);
    }
  }

  writeFileSyncIfChanged(docsJsonPath, `${JSON.stringify(docsJson, null, 2)}\n`);
}

function sliceAppObject(content: string, appKeyMatchIndex: number): string {
  const objectStart = content.indexOf("{", appKeyMatchIndex);
  let depth = 0;
  for (let i = objectStart; i < content.length; i++) {
    if (content[i] === "{") {
      depth++;
    } else if (content[i] === "}") {
      depth--;
      if (depth === 0) {
        return content.slice(objectStart, i + 1);
      }
    }
  }
  throw new Error("Could not parse app object in apps-frontend.tsx");
}

function extractNavigationItemsFromAppsFrontend(appId: string): NavigationItem[] {
  const content = fs.readFileSync(appsFrontendPath, "utf-8");
  const escapedAppId = appId.replace(/-/g, "\\-");
  const appKeyPattern = new RegExp(`\\n\\s*(?:"${escapedAppId}"|${escapedAppId}):\\s*\\{`);
  const appMatch = appKeyPattern.exec(content);
  if (appMatch == null) {
    throw new Error(`Could not find app "${appId}" in apps-frontend.tsx`);
  }

  const appObject = sliceAppObject(content, appMatch.index);
  const navItemsKeywordIndex = appObject.indexOf("navigationItems:");
  if (navItemsKeywordIndex === -1) {
    throw new Error(`App "${appId}" has no navigationItems in apps-frontend.tsx`);
  }

  const arrayStart = appObject.indexOf("[", navItemsKeywordIndex);
  let depth = 0;
  let arrayEnd = -1;
  for (let i = arrayStart; i < appObject.length; i++) {
    if (appObject[i] === "[") {
      depth++;
    } else if (appObject[i] === "]") {
      depth--;
      if (depth === 0) {
        arrayEnd = i;
        break;
      }
    }
  }
  if (arrayEnd === -1) {
    throw new Error(`Could not parse navigationItems for app "${appId}" in apps-frontend.tsx`);
  }

  const navBlock = appObject.slice(arrayStart, arrayEnd + 1);
  const items: NavigationItem[] = [];
  const displayNamePattern = /displayName:\s*"([^"]+)"/g;
  let labelMatch = displayNamePattern.exec(navBlock);
  while (labelMatch != null) {
    const objectStart = labelMatch.index;
    const objectEnd = navBlock.indexOf("},", objectStart);
    const objectSlice = navBlock.slice(objectStart, objectEnd === -1 ? navBlock.length : objectEnd + 2);
    items.push({
      displayName: labelMatch[1],
      external: /external:\s*true/.test(objectSlice),
    });
    labelMatch = displayNamePattern.exec(navBlock);
  }
  return items;
}

function discoverNavigableAppsFromAppsFrontend(): DiscoveredNavigableApp[] {
  const discovered: DiscoveredNavigableApp[] = [];

  for (const appId of Object.keys(ALL_APPS)) {
    let navItems: NavigationItem[];
    try {
      navItems = extractNavigationItemsFromAppsFrontend(appId);
    } catch (error) {
      const message = error instanceof Error ? error.message : String(error);
      if (message.includes("has no navigationItems") || message.includes("Could not find app")) {
        continue;
      }
      throw error;
    }

    const internalNavLabels = navItems
      .filter((item) => !item.external)
      .map((item) => item.displayName);

    if (internalNavLabels.length === 0) {
      continue;
    }

    discovered.push({ appId, navLabels: internalNavLabels });
  }

  discovered.sort((a, b) => a.appId.localeCompare(b.appId));
  return discovered;
}

function removeOrphanGeneratedMdx(dashboardReferenceApps: ReturnType<typeof buildDashboardReferenceApps>) {
  const expectedPaths = new Set(
    listDashboardReferencePages(dashboardReferenceApps).map(({ app, page }) => path.join(mdxRoot, app.appId, `${page.slug}.mdx`)),
  );

  for (const app of dashboardReferenceApps) {
    const appDir = path.join(mdxRoot, app.appId);
    if (!fs.existsSync(appDir)) {
      continue;
    }
    for (const entry of fs.readdirSync(appDir)) {
      if (!entry.endsWith(".mdx")) {
        continue;
      }
      const fullPath = path.join(appDir, entry);
      if (!expectedPaths.has(fullPath)) {
        fs.unlinkSync(fullPath);
        console.log(`Removed orphan generated file: ${fullPath}`);
      }
    }
  }
}

function main() {
  const jsdocDocs = extractDashboardReferenceJSDocs(repoRoot);
  const discoveredApps = discoverNavigableAppsFromAppsFrontend();
  const dashboardReferenceApps = buildDashboardReferenceApps(discoveredApps);
  const allPages = listDashboardReferencePages(dashboardReferenceApps);

  for (const { app, page } of allPages) {
    const body = readBody(jsdocDocs, app.appId, page.slug);
    const pageMetadata = mergePageMetadataFromJsdoc(app.appId, page.slug, page, jsdocDocs);
    const mdxPath = path.join(mdxRoot, app.appId, `${page.slug}.mdx`);
    fs.mkdirSync(path.dirname(mdxPath), { recursive: true });
    writeFileSyncIfChanged(mdxPath, renderMdx(pageMetadata, body));
  }

  removeOrphanGeneratedMdx(dashboardReferenceApps);

  patchDocsJson(buildDashboardReferenceNavGroup(dashboardReferenceApps), dashboardReferenceApps);

  execSync("pnpm run generate-setup-prompt-docs", {
    cwd: repoRoot,
    stdio: "inherit",
  });

  const documentedCount = allPages.filter(({ app, page }) => jsdocDocs.has(`${app.appId}/${page.slug}`)).length;
  console.log(
    `Generated dashboard reference docs for ${dashboardReferenceApps.length} apps, `
    + `${allPages.length} pages (${documentedCount} with JSDoc, ${allPages.length - documentedCount} placeholder).`,
  );
}

main();