import { Capacitor } from "@capacitor/core";
import {
  appVersionMeetsMinimum,
  changedFilesForPack,
  filesForContentPack,
  parseContentManifest,
  type ContentManifest,
  type ContentManifestFile,
} from "./contentManifest";
import { NativeContentStorage } from "./nativeContentStorage";

const CONTENT_STATE_KEY = "healer-man.content-state.v1";
const PRODUCTION_ORIGIN = "https://iwanttoheal.phenomrom.com";
const STATIC_ANDROID_BUNDLED_PACKS = new Set([
  "core:ui",
  "core:equipment",
  "core:character-basic",
  "core:runtime",
  "core:arenas",
  "dungeon:wailing-caverns",
]);
const STATIC_BROWSER_BUNDLED_PACKS = new Set([
  "core:ui",
  "core:equipment",
  "core:character-basic",
  "core:runtime",
  "core:arenas",
  "dungeon:wailing-caverns",
]);

export const BROWSER_CONTENT_CACHE_NAME = "healer-man-content-v1";
export const BROWSER_CONTENT_WORKER_URL = "/content-cache-sw.js";

export interface InstalledContentFile {
  readonly packId: string;
  readonly sha256: string;
  readonly bytes: number;
  readonly fileUri: string;
  readonly extension: string;
}

interface PersistedContentState {
  readonly version: 1;
  readonly packVersions: Readonly<Record<string, string>>;
  readonly files: Readonly<Record<string, InstalledContentFile>>;
}

export interface ContentManagerSnapshot {
  readonly revision: number;
  readonly installedRevision: number;
  readonly checking: boolean;
  readonly manifest: ContentManifest | null;
  readonly bundledManifest: ContentManifest | null;
  readonly installingPackId: string | null;
  readonly downloadedBytes: number;
  readonly totalBytes: number;
  readonly error: string;
}

const EMPTY_STATE: PersistedContentState = { version: 1, packVersions: {}, files: {} };
let installedState = readInstalledState();
let snapshot: ContentManagerSnapshot = {
  revision: 0,
  installedRevision: 0,
  checking: false,
  manifest: null,
  bundledManifest: null,
  installingPackId: null,
  downloadedBytes: 0,
  totalBytes: 0,
  error: "",
};
const listeners = new Set<() => void>();
let initialization: Promise<void> | null = null;

function safeLocalStorage(): Storage | null {
  try { return typeof window === "undefined" ? null : window.localStorage; } catch { return null; }
}

function readInstalledState(): PersistedContentState {
  try {
    const value = JSON.parse(safeLocalStorage()?.getItem(CONTENT_STATE_KEY) ?? "null") as Partial<PersistedContentState> | null;
    if (!value || value.version !== 1 || !value.files || !value.packVersions) return EMPTY_STATE;
    return { version: 1, files: value.files, packVersions: value.packVersions };
  } catch {
    return EMPTY_STATE;
  }
}

function persistInstalledState(): void {
  safeLocalStorage()?.setItem(CONTENT_STATE_KEY, JSON.stringify(installedState));
}

function publish(patch: Partial<Omit<ContentManagerSnapshot, "revision">>): void {
  snapshot = { ...snapshot, ...patch, revision: snapshot.revision + 1 };
  listeners.forEach((listener) => listener());
}

function contentOrigin(): string {
  const configured = String(import.meta.env.VITE_CONTENT_BASE_URL ?? "").replace(/\/+$/, "");
  if (configured) return configured;
  if (Capacitor.isNativePlatform()) return PRODUCTION_ORIGIN;
  return typeof window === "undefined" ? "" : window.location.origin;
}

function absoluteContentUrl(value: string): string {
  return new URL(value, `${contentOrigin() || "http://localhost"}/`).toString();
}

function browserCacheRequest(logicalPath: string): Request {
  const appOrigin = typeof window === "undefined" ? "http://localhost" : window.location.origin;
  return new Request(new URL(logicalPath, `${appOrigin}/`).toString(), { method: "GET" });
}

function browserCacheStorage(): CacheStorage | null {
  return typeof caches === "undefined" ? null : caches;
}

async function registerBrowserContentWorker(): Promise<void> {
  if (Capacitor.isNativePlatform()
    || import.meta.env.DEV
    || typeof navigator === "undefined"
    || !("serviceWorker" in navigator)) return;
  try {
    await navigator.serviceWorker.register(BROWSER_CONTENT_WORKER_URL, {
      scope: "/",
      updateViaCache: "none",
    });
    await navigator.serviceWorker.ready;
  } catch (error) {
    console.warn("Browser content cache worker could not be registered.", error);
  }
}

function extensionForEntry(entry: ContentManifestFile): string {
  const match = /(?:\.[A-Za-z0-9]+)(?:\?.*)?$/.exec(entry.url);
  return match?.[0].split("?")[0].toLowerCase() ?? ".bin";
}

function bundledFiles(): Readonly<Record<string, { readonly sha256: string }>> {
  if (snapshot.bundledManifest) return snapshot.bundledManifest.files;
  if (!snapshot.manifest) return {};
  const bundledPacks = Capacitor.isNativePlatform()
    ? STATIC_ANDROID_BUNDLED_PACKS
    : STATIC_BROWSER_BUNDLED_PACKS;
  return Object.fromEntries(Object.entries(snapshot.manifest.files).filter(([, entry]) => (
    bundledPacks.has(entry.packId)
  )));
}

function activeFileIdentities(): Readonly<Record<string, { readonly sha256: string }>> {
  return { ...bundledFiles(), ...installedState.files };
}

export function subscribeContentManager(listener: () => void): () => void {
  listeners.add(listener);
  return () => listeners.delete(listener);
}

export function getContentManagerSnapshot(): ContentManagerSnapshot {
  return snapshot;
}

export function resolveContentUrl(logicalUrl: string): string {
  if (!Capacitor.isNativePlatform()) return logicalUrl;
  let pathname = logicalUrl;
  try { pathname = new URL(logicalUrl, "https://local.invalid").pathname; } catch { /* preserve original */ }
  const installed = installedState.files[pathname];
  return installed?.fileUri ? Capacitor.convertFileSrc(installed.fileUri) : logicalUrl;
}

export function contentPackIsBundled(packId: string): boolean {
  if (!Capacitor.isNativePlatform()) return STATIC_BROWSER_BUNDLED_PACKS.has(packId);
  return STATIC_ANDROID_BUNDLED_PACKS.has(packId)
    || Boolean(snapshot.bundledManifest?.packs.some((pack) => pack.id === packId));
}

export function contentPackIsInstalled(packId: string): boolean {
  return contentPackIsBundled(packId) || Boolean(installedState.packVersions[packId]);
}

export function contentPackIsUsable(packId: string): boolean {
  if (contentPackIsBundled(packId)) return true;
  if (!installedState.packVersions[packId]) return false;
  const pack = snapshot.manifest?.packs.find((candidate) => candidate.id === packId);
  return pack?.dependencies.every((dependency) => contentPackIsUsable(dependency)) ?? true;
}

export function contentPackHasUpdate(packId: string): boolean {
  if (!snapshot.manifest || !contentPackIsInstalled(packId)) return false;
  const pack = snapshot.manifest.packs.find((candidate) => candidate.id === packId);
  return changedFilesForPack(snapshot.manifest, packId, activeFileIdentities()).length > 0
    || Boolean(!contentPackIsBundled(packId)
      && pack?.dependencies.some((dependency) => (
        !contentPackIsUsable(dependency) || contentPackHasUpdate(dependency)
      )));
}

export async function checkForContentUpdates(): Promise<ContentManifest | null> {
  publish({ checking: true, error: "" });
  try {
    const response = await fetch(`${contentOrigin()}/content/manifest.json`, { cache: "no-cache" });
    if (!response.ok) throw new Error(`Content catalog request failed (${response.status}).`);
    const manifest = parseContentManifest(await response.json());
    publish({ manifest, checking: false });
    return manifest;
  } catch (error) {
    publish({ checking: false, error: error instanceof Error ? error.message : "Content server is unavailable." });
    return null;
  }
}

async function loadBundledManifest(): Promise<void> {
  if (!Capacitor.isNativePlatform() && import.meta.env.VITE_CONTENT_MODE !== "downloadable") return;
  try {
    const response = await fetch("/content/bootstrap-manifest.json", { cache: "force-cache" });
    if (!response.ok) return;
    publish({ bundledManifest: parseContentManifest(await response.json()) });
  } catch {
    // The static bundled-pack list still keeps the starter dungeon available.
  }
}

export function initializeContentSystem(): Promise<void> {
  if (!initialization) {
    initialization = (async () => {
      await Promise.all([loadBundledManifest(), registerBrowserContentWorker()]);
      if (typeof navigator === "undefined" || navigator.onLine !== false) void checkForContentUpdates();
    })();
  }
  return initialization;
}

async function sha256Bytes(bytes: ArrayBuffer): Promise<string> {
  if (!globalThis.crypto?.subtle) {
    throw new Error("This browser cannot verify downloaded content.");
  }
  const digest = await globalThis.crypto.subtle.digest("SHA-256", bytes);
  return [...new Uint8Array(digest)].map((value) => value.toString(16).padStart(2, "0")).join("");
}

async function installBrowserContentPack(
  packId: string,
  manifest: ContentManifest,
  changes: ReturnType<typeof changedFilesForPack>,
): Promise<void> {
  const storage = browserCacheStorage();
  if (!storage) throw new Error("Offline content storage is unavailable in this browser.");

  const totalBytes = changes.reduce((total, [, entry]) => total + entry.bytes, 0);
  const stagingName = `${BROWSER_CONTENT_CACHE_NAME}-staging-${encodeURIComponent(packId)}`;
  await storage.delete(stagingName);
  const staging = await storage.open(stagingName);
  publish({ installingPackId: packId, downloadedBytes: 0, totalBytes, error: "" });

  let completedBytes = 0;
  try {
    for (const [logicalPath, entry] of changes) {
      const response = await fetch(absoluteContentUrl(entry.url), { cache: "no-store" });
      if (!response.ok) throw new Error(`Content request failed (${response.status}): ${logicalPath}`);
      const bytes = await response.arrayBuffer();
      if (bytes.byteLength !== entry.bytes) {
        throw new Error(`Downloaded content has the wrong size: ${logicalPath}`);
      }
      if (await sha256Bytes(bytes) !== entry.sha256) {
        throw new Error(`Downloaded content failed verification: ${logicalPath}`);
      }
      const headers = new Headers();
      const contentType = response.headers.get("content-type");
      if (contentType) headers.set("content-type", contentType);
      await staging.put(browserCacheRequest(logicalPath), new Response(bytes, {
        headers,
        status: 200,
      }));
      completedBytes += entry.bytes;
      publish({ downloadedBytes: completedBytes });
    }

    const active = await storage.open(BROWSER_CONTENT_CACHE_NAME);
    for (const [logicalPath] of changes) {
      const cached = await staging.match(browserCacheRequest(logicalPath));
      if (!cached) throw new Error(`Verified content was not staged: ${logicalPath}`);
      await active.put(browserCacheRequest(logicalPath), cached);
    }

    const pendingFiles = { ...installedState.files };
    const latestPaths = new Set(filesForContentPack(manifest, packId).map(([logicalPath]) => logicalPath));
    for (const [logicalPath, installed] of Object.entries(pendingFiles)) {
      if (installed.packId !== packId || latestPaths.has(logicalPath)) continue;
      await active.delete(browserCacheRequest(logicalPath));
      delete pendingFiles[logicalPath];
    }
    for (const [logicalPath, entry] of filesForContentPack(manifest, packId)) {
      pendingFiles[logicalPath] = {
        packId,
        sha256: entry.sha256,
        bytes: entry.bytes,
        extension: extensionForEntry(entry),
        fileUri: absoluteContentUrl(logicalPath),
      };
    }
    installedState = {
      version: 1,
      files: pendingFiles,
      packVersions: { ...installedState.packVersions, [packId]: manifest.version },
    };
    persistInstalledState();
    publish({
      installingPackId: null,
      downloadedBytes: totalBytes,
      totalBytes,
      error: "",
      installedRevision: snapshot.installedRevision + 1,
    });
  } catch (error) {
    publish({ installingPackId: null, error: error instanceof Error ? error.message : "Content download failed." });
    throw error;
  } finally {
    await storage.delete(stagingName).catch(() => false);
  }
}

export async function installContentPack(packId: string): Promise<void> {
  const manifest = snapshot.manifest ?? await checkForContentUpdates();
  if (!manifest) throw new Error(snapshot.error || "Content server is unavailable.");
  if (!appVersionMeetsMinimum(import.meta.env.VITE_APP_VERSION, manifest.minimumAppVersion)) {
    throw new Error(`Healer Man ${manifest.minimumAppVersion} or newer is required for this content.`);
  }
  const pack = manifest.packs.find((candidate) => candidate.id === packId);
  if (!pack) throw new Error(`Unknown content pack: ${packId}`);

  if (!contentPackIsBundled(packId)) {
    for (const dependency of pack.dependencies) {
      if (!contentPackIsUsable(dependency) || contentPackHasUpdate(dependency)) {
        await installContentPack(dependency);
      }
    }
  }

  const changes = changedFilesForPack(manifest, packId, activeFileIdentities());
  if (!Capacitor.isNativePlatform()) {
    await installBrowserContentPack(packId, manifest, changes);
    return;
  }
  const totalBytes = changes.reduce((total, [, entry]) => total + entry.bytes, 0);
  const storage = await NativeContentStorage.getFreeBytes();
  const safetyReserve = 128 * 1024 * 1024;
  if (storage.freeBytes < totalBytes + safetyReserve) {
    const error = `Not enough free storage. ${Math.ceil((totalBytes + safetyReserve - storage.freeBytes) / 1024 / 1024)} MB more is required.`;
    publish({ error });
    throw new Error(error);
  }
  publish({ installingPackId: packId, downloadedBytes: 0, totalBytes, error: "" });
  let completedBytes = 0;
  const pendingFiles = { ...installedState.files };
  const progressHandle = await NativeContentStorage.addListener("downloadProgress", (progress) => {
    publish({ downloadedBytes: Math.min(totalBytes, completedBytes + progress.downloadedBytes) });
  });

  try {
    for (const [logicalPath, entry] of changes) {
      const extension = extensionForEntry(entry);
      const result = await NativeContentStorage.download({
        url: absoluteContentUrl(entry.url),
        logicalPath,
        sha256: entry.sha256,
        extension,
        bytes: entry.bytes,
      });
      pendingFiles[logicalPath] = {
        packId,
        sha256: entry.sha256,
        bytes: entry.bytes,
        extension,
        fileUri: result.fileUri,
      };
      completedBytes += entry.bytes;
      publish({ downloadedBytes: completedBytes });
    }

    const latestPaths = new Set(filesForContentPack(manifest, packId).map(([logicalPath]) => logicalPath));
    for (const [logicalPath, installed] of Object.entries(pendingFiles)) {
      if (installed.packId === packId && !latestPaths.has(logicalPath)) delete pendingFiles[logicalPath];
    }
    installedState = {
      version: 1,
      files: pendingFiles,
      packVersions: { ...installedState.packVersions, [packId]: manifest.version },
    };
    persistInstalledState();
    publish({
      installingPackId: null,
      downloadedBytes: totalBytes,
      totalBytes,
      error: "",
      installedRevision: snapshot.installedRevision + 1,
    });
  } catch (error) {
    publish({ installingPackId: null, error: error instanceof Error ? error.message : "Content download failed." });
    throw error;
  } finally {
    await progressHandle.remove();
  }
}

export async function removeContentPack(packId: string): Promise<void> {
  if (contentPackIsBundled(packId)) return;
  const remainingFiles = { ...installedState.files };
  const targetFiles = Object.entries(remainingFiles).filter(([, entry]) => entry.packId === packId);
  if (Capacitor.isNativePlatform()) {
    for (const [logicalPath, entry] of targetFiles) {
      const shared = Object.entries(remainingFiles).some(([otherPath, other]) => (
        otherPath !== logicalPath && other.sha256 === entry.sha256 && other.extension === entry.extension && other.packId !== packId
      ));
      if (!shared) await NativeContentStorage.remove({ sha256: entry.sha256, extension: entry.extension });
      delete remainingFiles[logicalPath];
    }
  } else {
    const storage = browserCacheStorage();
    if (!storage) throw new Error("Offline content storage is unavailable in this browser.");
    const active = await storage.open(BROWSER_CONTENT_CACHE_NAME);
    for (const [logicalPath] of targetFiles) {
      await active.delete(browserCacheRequest(logicalPath));
      delete remainingFiles[logicalPath];
    }
  }
  const packVersions = { ...installedState.packVersions };
  delete packVersions[packId];
  installedState = { version: 1, files: remainingFiles, packVersions };
  persistInstalledState();
  publish({ error: "", installedRevision: snapshot.installedRevision + 1 });
}