/// <reference lib="deno.unstable" />

import { denoPlugins } from "https://deno.land/x/esbuild_deno_loader@0.8.2/mod.ts";
import * as esbuild from "https://deno.land/x/esbuild@v0.19.4/wasm.js";
import {
  collectAndCleanScripts,
  getHashSync,
  scripted,
  storeFunctionExecution,
} from "https://deno.land/x/scripted@0.0.3/mod.ts";
import { walk } from "https://deno.land/std@0.204.0/fs/walk.ts";
import {
  dirname,
  join,
  relative,
  toFileUrl,
} from "https://deno.land/std@0.204.0/path/mod.ts";

import { getIslands, IslandDef } from "https://deno.land/x/islet@0.0.22/client.ts";

interface Snapshot {
  build_id: string;
  files: Record<string, string[]>;
}

const files = [];
for await (
  const { path } of walk(Deno.cwd(), {
    maxDepth: 10,
    exts: [".js", ".jsx", ".tsx", ".ts", ".json"],
  })
) {
  if (!path.includes("_islet")) {
    files.push({ url: path, size: (await Deno.stat(path)).size });
  }
}
let buildId = getHashSync(
  JSON.stringify(files.toSorted((a, b) => a.url.localeCompare(b.url))),
);
console.log(buildId, files, Deno.cwd());
const setBuildId = (id: string) => (buildId = id);

const createIslandId = (key: string) =>
  getHashSync(
    [buildId, relative(import.meta.resolve("./"), key)]
      .filter((v) => v)
      .join("_"),
  );

export const getIslandUrl = <T>(fn: T, key = "default") =>
  `/islands/${createIslandId(getIslands(key).get(fn)?.url!)}.js`;

export const config = {
  routeOverride: "/islands/:id*",
};

function deepApply<T>(data: T, applyFn): T {
  function isObject(object: unknown): object is Record<keyof never, unknown> {
    return object instanceof Object && object.constructor === Object;
  }
  if (Array.isArray(data)) {
    return (data as unknown[]).map((value) =>
      isObject(value) ? deepApply(value, applyFn) : value
    ) as unknown as T;
  }
  const entries = Object.entries(data as Record<string, unknown>).reduce(
    (p, [key, value]) => {
      const r = applyFn(key, value, p);
      return r;
    },
    data,
  );
  const clean = Object.entries(entries).map(([key, v]) => {
    const value = isObject(v) ? deepApply(v, applyFn) : v;
    return [key, value];
  });
  return Object.fromEntries(clean) as T;
}

const createCounter = (startAt = 0) => ((i) => () => i++)(startAt); // prettier-ignore
const initCounter = createCounter(0);
const buildCounter = createCounter(0);
const transformCounter = createCounter(0);

class SuffixTransformStream extends TransformStream<Uint8Array, Uint8Array> {
  constructor(suffix: string) {
    super({
      flush(controller) {
        controller.enqueue(new TextEncoder().encode(suffix));
        controller.terminate();
      },
    });
  }
}

export interface Manifest {
  key?: string;
  baseUrl: URL;
  // islands: URL | URL[];
  prefix: string;
  jsxImportSource: string;
  buildDir?: string;
  importMapFileName?: string;
  esbuildOptions?: Partial<Parameters<typeof esbuild.build>[0]>;
  openKv: () => ReturnType<typeof Deno.openKv>;
  dev?: boolean;
}

const esbuildState = ((
  done = false,
  ongoingPromise: null | Promise<null | void> = null,
) => ({
  isInitialized: () => done,
  init: () => {
    if (ongoingPromise) return ongoingPromise;
    const id = initCounter();
    console.time(`[init-${id}] ${esbuild.version}`);
    const wasmURL =
      `https://raw.githubusercontent.com/esbuild/deno-esbuild/v${esbuild.version}/esbuild.wasm`;
    ongoingPromise = esbuild
      .initialize(
        !globalThis.Worker || Deno.Command === undefined
          ? { wasmURL, worker: false }
          : {},
      )
      .then(() => {
        done = true;
        console.timeEnd(`[init-${id}] ${esbuild.version}`);
      })
      .catch((err) =>
        err.toString().includes("more than once") ? null : console.error(err)
      );

    return ongoingPromise!;
  },
}))();

type EsBuild = Awaited<ReturnType<typeof esbuild.build>>;

interface SnapshotReader {
  getPaths: () => string[];
  read: (path: string) => Promise<ReadableStream<Uint8Array> | null>;
  dependencies: (path: string) => string[];
  json: () => {
    [k: string]: string[] | undefined;
  };
}

const buildSnapshot = (
  buildOptions: esbuild.BuildOptions,
  bundle: EsBuild,
): SnapshotReader => {
  const absWorkingDirLen = toFileUrl(buildOptions.absWorkingDir!).href.length +
    1;
  const files = new Map<string, Uint8Array>();
  const dependencies = new Map<string, string[]>();
  for (const file of bundle.outputFiles!) {
    const path = toFileUrl(file.path).href.slice(absWorkingDirLen);
    files.set(path, file.contents);
  }

  const metaOutputs = new Map(Object.entries(bundle.metafile!.outputs));

  for (const [path, entry] of metaOutputs.entries()) {
    const imports = entry.imports
      .filter(({ kind }) => kind === "import-statement")
      .map(({ path }) => path);
    dependencies.set(path, imports);
  }

  return {
    getPaths: () => Array.from(files.keys()),
    read: (path: string) =>
      Promise.resolve(
        files.get(path)
          ? new ReadableStream({
            start(controller) {
              controller.enqueue(files.get(path)!);
              controller.close();
            },
          })
          : null,
      ),
    dependencies: (path: string) => dependencies.get(path) ?? [],
    json: () =>
      Object.fromEntries(
        Array.from(files.keys()).map((key) => [key, dependencies.get(key)]),
      ),
  };
};

const snapshotFromJson = (
  json: Snapshot,
  snapshotDirPath: string,
): SnapshotReader => {
  const dependencies = new Map<string, string[]>(Object.entries(json.files));

  const files = new Map<string, string>();
  Object.keys(json.files).forEach((name) => {
    const filePath = join(snapshotDirPath, name);
    files.set(name, filePath);
  });

  return {
    getPaths: () => Array.from(files.keys()),
    read: async (path: string) => {
      const filePath = files.get(path);
      if (filePath !== undefined) {
        try {
          const file = await Deno.open(filePath, { read: true });
          return file.readable;
        } catch (_err) {
          return null;
        }
      }

      // Handler will turn this into a 404
      return null;
    },
    dependencies: (path: string) => dependencies.get(path) ?? [],
    json: () =>
      Object.fromEntries(
        Array.from(files.keys()).map((key) => [key, dependencies.get(key)]),
      ),
  };
};

const transformScript = async (script: string) => {
  esbuildState.init().catch(console.error);
  if (!esbuildState.isInitialized()) return script;
  const id = `[esbuild-${transformCounter()}] transform`;
  console.time(id);
  const scripts = await esbuild.transform(script, { minify: true });
  console.timeEnd(id);
  return scripts.code;
};

export const addScripts = async (
  html: string | ReadableStream,
  minify = true,
): Promise<typeof html> => {
  const scripts = collectAndCleanScripts();
  const code = minify ? await transformScript(scripts) : scripts;
  const script = `<script type="module" defer>${code}</script>`;
  if (html instanceof ReadableStream) {
    return html.pipeThrough(new SuffixTransformStream(script));
  }
  return `${
    html.replace(
      html.includes("</body>") ? /(<\/body>)/ : /(.*)/,
      (_, $1) => `${script}${$1}`,
    )
  }`;
};

interface IslandHandlerGetter {
  get: (id: string) => ReturnType<SnapshotReader["read"]>;
}

const createIslands = async (
  manifest: Manifest,
  initSnapshot: SnapshotReader | null,
  snapshotPath: string,
): Promise<IslandHandlerGetter> => {
  if (initSnapshot) {
    return { get: (id: string) => initSnapshot.read("islands/" + id) };
  }

  const absWorkingDir = Deno.cwd();
  const buildConfig: Parameters<typeof esbuild.build>[0] = {
    plugins: [
      ...denoPlugins({
        loader: "native",
        configPath: new URL(
          manifest.importMapFileName ?? "deno.json",
          manifest.baseUrl,
        ).href.slice(7),
      }),
    ],
    entryPoints: [
      ...Array.from(getIslands(manifest.key ?? "default")).map(
        ([, island]) => ({
          out: createIslandId(island.url),
          in: island.url,
        }),
      ),
    ],
    platform: "browser",
    target: ["chrome99", "firefox99", "safari15"],
    format: "esm",
    jsx: manifest.jsxImportSource ? "automatic" : "transform",
    jsxFactory: "h",
    jsxFragment: "Fragment",
    jsxImportSource: manifest.jsxImportSource,
    bundle: true,
    splitting: true,
    metafile: true,
    treeShaking: true,
    outdir: manifest.prefix,
    absWorkingDir,
    write: false,
    sourcemap: manifest.dev ? "linked" : false,
    minify: true,
    ...(manifest.esbuildOptions ?? {}),
  };

  const bundle = await esbuildState
    .init()
    .then(() => esbuild.build(buildConfig));
  const buildDir = dirname(snapshotPath);
  const id = `[esbuild-${buildCounter()}] build`;
  console.time(id);
  const snapshotReader = buildSnapshot(buildConfig, bundle);
  console.timeEnd(id);
  await Deno.remove(buildDir, { recursive: true }).catch(() => null);
  await Deno.mkdir(buildDir, { recursive: true }).catch(() => null);
  await Promise.all(
    snapshotReader.getPaths().map(async (fileName) => {
      const data = await snapshotReader.read(fileName);
      if (data === null) return;

      const path = join(buildDir, fileName);
      await Deno.mkdir(dirname(path), { recursive: true }).catch(() => null);
      return Deno.writeFile(path, data);
    }),
  );

  await Deno.writeTextFile(
    snapshotPath,
    JSON.stringify(
      { build_id: buildId, files: snapshotReader.json() },
      null,
      2,
    ),
  );

  return {
    get: (id: string) => snapshotReader.read("islands/" + id),
  };
};

export const createHandler = async (manifest: Manifest) => {
  const promiseCache: Map<string, Promise<IslandHandlerGetter>> = new Map();

  const buildDir = manifest.buildDir ?? "_islet";
  const snapshotPath = join(buildDir, "snapshot.json");
  const json: Snapshot | null = JSON.parse(
    await Deno.readTextFile(snapshotPath).catch(() => "null"),
  );
  const snapshot = json?.build_id === buildId
    ? snapshotFromJson(json, buildDir)
    : null;
  if (json?.build_id === buildId) setBuildId(json.build_id);
  console.log(json, snapshot);

  return async (_req: Request, _ctx: any, match: Record<string, string>) => {
    if (!promiseCache.has(manifest.baseUrl.href)) {
      console.log(manifest.baseUrl.href);
      promiseCache.set(
        manifest.baseUrl.href,
        createIslands(manifest, snapshot, snapshotPath),
      );
    }
    const islands = await promiseCache.get(manifest.baseUrl.href)!;
    const contents = await islands.get(match.id);
    return contents
      ? new Response(contents, {
        headers: {
          "content-type": "text/javascript",
          "Cache-Control": "public, max-age=31536000, immutable",
        },
      })
      : new Response(null, { status: 404 });
  };
};

type HydrateFn = (
  container: Element | Document,
  initialChildren: VNode,
) => Root;

const hydrate = (
  node: HTMLElement,
  specifier: string,
  exportName: string,
): void => {
  const closest = node.parentElement?.closest("[data-islet-type=island]");
  if (closest) return;

  const parseStyleStr = (styleStr: string): { [key: string]: string } =>
    styleStr
      .split(";")
      .map((style) => style.split(":").map((d) => d.trim()))
      .reduce((acc, [key, value]) => ({ ...acc, [key]: value }), {});

  const processAttributes = (
    attributes: NamedNodeMap,
  ): Record<string, unknown> =>
    Array.from(attributes).reduce(
      (acc, { name, value }) => {
        acc[name === "class" ? "className" : name] = name === "style"
          ? parseStyleStr(value)
          : value;
        return acc;
      },
      { key: Math.random() },
    );

  const getType = async (node: HTMLElement) =>
    node.dataset?.isletType === "island"
      ? await import(window._ISLET[node.dataset.isletId].url).then(
        (module) =>
          module[window._ISLET[node.dataset.isletId].exportName ?? "default"],
      )
      : null;

  const toVirtual = async (h, node: Element | null): Promise<any> => {
    if (node?.nodeType !== 1) return node?.textContent;

    const tagName = node.tagName?.toLowerCase();
    const attributes = processAttributes(node.attributes ?? {});
    const children = node.childNodes.length > 0
      ? await Promise.all(
        [...node.childNodes].map((child) => toVirtual(h, child)),
      )
      : null;

    const type = await getType(node);
    if (!type) return h(tagName, attributes, children);

    const islandProps = JSON.parse(window._ISLET[node.dataset.isletId].props);
    islandProps.children = await toVirtual(
      h,
      node.querySelector("[data-islet-type]"),
    );

    return h(tagName, attributes, h(type, islandProps));
  };

  const mapAsync = (arr, fn) => Promise.all(arr.map(async (x) => await fn(x)));

  const transformStaticNodeToVirtual = async (h, props) =>
    Object.fromEntries(
      await mapAsync(Object.entries(props), async ([k, v]) => {
        if (v?.specifier) {
          const [importedV, propsV] = await Promise.all([
            import(v.specifier),
            transformStaticNodeToVirtual(h, v.props),
          ]);
          return [k, h(importedV[v.exportName], propsV)];
        } else if (v?.type) {
          return [k, h(v.type, await transformStaticNodeToVirtual(h, v.props))];
        } else return [k, v];
      }),
    );

  const renderTask = () =>
    import(specifier).then(async (o: { h: typeof h; hydrate: HydrateFn }) => {
      const { h, hydrate: rawHydrate, withFragment } = o;
      const type = o[exportName];
      const hydrate = (a: unknown, b: unknown) =>
        rawHydrate.length === 2 ? rawHydrate(a, b) : rawHydrate(b, a);
      const container = withFragment ? document.createDocumentFragment() : node;
      const children = await toVirtual(
        h,
        node.querySelector("[data-islet-type]"),
      );
      const props = JSON.parse(window._ISLET[node.dataset.isletId].props);
      props.children = children;
      const resolvedProps = await transformStaticNodeToVirtual(h, props);
      hydrate(h(type, resolvedProps), container);
    });

  "scheduler" in globalThis
    ? globalThis.scheduler!.postTask(renderTask)
    : setTimeout(renderTask, 0);
};

const createIslandScript = (prefix: string, { url, exportName }: IslandDef) => {
  const id = createIslandId(url);
  return scripted(hydrate, `${prefix}/islands/${id}.js`, exportName);
};

const transformVirtualNodeToStatic = (params, islands) => {
  const newParams = deepApply(
    params,
    (key: string, value: unknown, obj: Record<string, unknown>) => {
      const component = key === "type" &&
          islands.get(value?.type ?? value) &&
          typeof value === "function"
        ? islands.get(value?.type ?? value)
        : null;
      if (component) {
        const id = createIslandId(component.url);
        return {
          ...obj,
          [key]: value,
          specifier: `/islands/${id}.js`,
          exportName: component.exportName,
        };
      }
      return key.startsWith("__") ? { ...obj, [key]: undefined } : obj;
    },
  );
  return newParams;
};

const jsonStringifyWithBigIntSupport = (data: unknown) => {
  if (data !== undefined) {
    return JSON.stringify(
      data,
      (_, v) => typeof v === "bigint" ? `${v}#bigint` : v,
    ).replace(/"(-?\d+)#bigint"/g, (_, a) => a);
  }
};

export const createJsx = ({
  jsx,
  h,
  Fragment,
  cloneElement,
  prefix = "",
  key: islandKey = "default",
}) =>
(
  type: Parameters<typeof jsx>[0],
  params: Parameters<typeof jsx>[1],
  key: Parameters<typeof jsx>[2],
  ...props
) => {
  const islands = getIslands(islandKey);
  const island = islands.get(type);
  const isletData = !island ? null : {
    url: `${prefix}/islands/${createIslandId(island.url)}.js`,
    exportName: island.exportName,
    props: jsonStringifyWithBigIntSupport({
      ...transformVirtualNodeToStatic(params, islands),
      children: undefined,
    }),
  };
  const isletId = island ? getHashSync(JSON.stringify(isletData)) : null;
  if (island) {
    storeFunctionExecution((isletId: string, isletData: unknown) => {
      window._ISLET = Object.assign(
        { [isletId]: isletData },
        window._ISLET || {},
      );
    }, ...[isletId, isletData]);
  }
  const className = island ? createIslandScript(prefix, island) : null;
  const children = h(type, params, key, ...props);
  const result = h(island ? "fragment" : Fragment, {
    style: { display: "contents" },
    className,
    ...(island
      ? { "data-islet-type": "island", "data-islet-id": isletId }
      : {}),
    children: !island ? children : cloneElement(children, {
      children: children.props.children
        ? [
          h("fragment", {
            style: { display: "contents" },
            "data-islet-type": "slot",
            children: children.props.children,
          }),
        ]
        : null,
    }),
  });
  return island ? result : result.props.children;
};