import { type Context, Hono } from "hono";
import { deleteCookie, getCookie, setCookie } from "hono/cookie";
import { validator } from "hono/validator";
import type { AssetBundle } from "../lib/asset_bundle/bundle.ts";
import { handleShellEndpoint } from "./shell_endpoint.ts";
import type { KvPrimitives } from "../lib/data/kv_primitives.ts";
import { compile as gitIgnoreCompiler } from "gitignore-parser";
import { decodePageURI } from "@silverbulletmd/silverbullet/lib/ref";
import { LockoutTimer } from "./lockout.ts";
import type { AuthOptions } from "../cmd/server.ts";
import type { BootConfig } from "../web/ui_types.ts";
import { applyUrlPrefix, removeUrlPrefix } from "../lib/url_prefix.ts";
import { authCookieName, fileMetaToHeaders, utcDateString } from "./util.ts";
import { renderHtmlPage } from "./serverside_render.ts";
import { FilteredSpacePrimitives } from "../lib/spaces/filtered_space_primitives.ts";
import { AssetBundlePlugSpacePrimitives } from "../lib/spaces/asset_bundle_space_primitives.ts";
import { determineStorageBackend } from "./storage_backend.ts";
import { ReadOnlySpacePrimitives } from "../lib/spaces/ro_space_primitives.ts";
import type { SpacePrimitives } from "../lib/spaces/space_primitives.ts";
import { JWTIssuer } from "./crypto.ts";
import {
  determineShellBackend,
  NotSupportedShell,
  type ShellBackend,
} from "./shell_backend.ts";
import { CONFIG_TEMPLATE, INDEX_TEMPLATE } from "../web/PAGE_TEMPLATES.ts";
import {
  CheckPathSpacePrimitives,
} from "../lib/spaces/checked_space_primitives.ts";
import { notFoundError } from "../lib/constants.ts";

const authenticationExpirySeconds = 60 * 60 * 24 * 7; // 1 week

export type ServerOptions = {
  hostname: string;
  port: number;
  hostUrlPrefix?: string;
  auth?: AuthOptions;
  spaceIgnore?: string;
  pagesPath: string;
  shellBackend: string;
  shellCommandWhiteList?: string[];
  readOnly: boolean;
  indexPage: string;
};

export class HttpServer {
  private abortController?: AbortController;
  private readonly hostname: string;
  private readonly port: number;
  private app: Hono;
  private readonly spacePrimitives: SpacePrimitives;
  private jwtIssuer: JWTIssuer;
  private readonly shellBackend: ShellBackend;

  constructor(
    readonly options: ServerOptions,
    private clientAssetBundle: AssetBundle,
    private plugAssetBundle: AssetBundle,
    public baseKvPrimitives: KvPrimitives,
  ) {
    this.app = new Hono().basePath(options.hostUrlPrefix ?? "");
    this.hostname = options.hostname;
    this.port = options.port;

    let fileFilterFn: (s: string) => boolean = () => true;
    if (options.spaceIgnore) {
      fileFilterFn = gitIgnoreCompiler(options.spaceIgnore).accepts;
    }

    this.spacePrimitives = new CheckPathSpacePrimitives(
      new FilteredSpacePrimitives(
        new AssetBundlePlugSpacePrimitives(
          determineStorageBackend(options.pagesPath),
          this.plugAssetBundle,
        ),
        (meta) => fileFilterFn(meta.name),
      ),
    );

    if (options.readOnly) {
      this.spacePrimitives = new ReadOnlySpacePrimitives(this.spacePrimitives);
    }
    this.shellBackend = options.readOnly
      ? new NotSupportedShell() // No shell for read only mode
      : determineShellBackend(options);
    this.jwtIssuer = new JWTIssuer(baseKvPrimitives);
  }

  async start() {
    if (this.options.auth) {
      // Initialize JWT issuer
      await this.jwtIssuer.init(
        JSON.stringify({ auth: this.options.auth }),
      );
    }
    await this.ensureBasicPages();
    // Serve static files (javascript, css, html)
    this.serveStatic();
    this.addAuth();
    this.app.route("/.fs", this.buildFsRoutes());

    // Fallback, serve the UI index.html
    this.app.use("*", (c) => {
      const url = new URL(this.unprefixedUrl(c.req.url));
      const pageName = decodePageURI(url.pathname.slice(1));
      return renderHtmlPage(
        this.spacePrimitives,
        pageName,
        c,
        this.options,
        this.clientAssetBundle,
      );
    });

    this.abortController = new AbortController();
    const listenOptions: any = {
      hostname: this.hostname,
      port: this.port,
      signal: this.abortController.signal,
    };

    // Start the actual server
    Deno.serve(listenOptions, this.app.fetch);

    const visibleHostname = this.hostname === "0.0.0.0"
      ? "localhost"
      : this.hostname;
    console.log(
      `SilverBullet is now running: http://${visibleHostname}:${this.port}`,
    );
  }

  serveStatic() {
    this.app.use("*", (c, next): Promise<void | Response> => {
      const req = c.req;
      const url = new URL(this.unprefixedUrl(req.url));
      if (
        url.pathname === "/"
      ) {
        // Serve the UI (index.html)
        const indexPage = this.options.indexPage ?? "index";
        return renderHtmlPage(
          this.spacePrimitives,
          indexPage,
          c,
          this.options,
          this.clientAssetBundle,
        );
      }
      try {
        const assetName = url.pathname.slice(1);
        if (!this.clientAssetBundle.has(assetName)) {
          return next();
        }
        if (
          this.clientAssetBundle.has(assetName) &&
          req.header("If-Modified-Since") ===
            utcDateString(this.clientAssetBundle.getMtime(assetName))
        ) {
          return Promise.resolve(c.body(null, 304));
        }
        c.status(200);
        c.header("Content-type", this.clientAssetBundle.getMimeType(assetName));
        const data = this.clientAssetBundle.readFileSync(
          assetName,
        );
        c.header("Content-length", "" + data.length);
        c.header(
          "Last-Modified",
          utcDateString(this.clientAssetBundle.getMtime(assetName)),
        );

        if (req.method === "GET") {
          return Promise.resolve(c.body(new Uint8Array(data).buffer));
        } // else e.g. HEAD, OPTIONS, don't send body
      } catch {
        return next();
      }
      return Promise.resolve();
    });
  }

  stop() {
    if (this.abortController) {
      this.abortController.abort();
      console.log("stopped server");
    }
  }

  private addAuth() {
    const excludedPaths = [
      "/manifest.json",
      "/favicon.png",
      "/logo.png",
      "/.auth",
    ];

    // Since we're a single user app, we can use a single lockout timer to prevent brute force attacks
    const lockoutTimer = this.options.auth?.lockoutLimit
      ? new LockoutTimer(
        // Turn into ms
        this.options.auth.lockoutTime * 1000,
        this.options.auth.lockoutLimit!,
      )
      : new LockoutTimer(0, 0); // disabled

    this.app.get("/.logout", (c) => {
      const url = new URL(this.unprefixedUrl(c.req.url));
      deleteCookie(c, authCookieName(url.host), {
        path: `${this.options.hostUrlPrefix ?? ""}/`,
      });
      deleteCookie(c, "refreshLogin", {
        path: `${this.options.hostUrlPrefix ?? ""}/`,
      });

      return c.redirect(this.prefixedUrl("/.auth"));
    });

    // Authentication endpoints
    this.app.get("/.auth", (c) => {
      const html = this.clientAssetBundle.readTextFileSync(".client/auth.html")
        .replaceAll("{{HOST_URL_PREFIX}}", this.options.hostUrlPrefix ?? "");

      return c.html(html);
    }).post(
      validator("form", (value: any, c: Context) => {
        const username = value["username"];
        const password = value["password"];
        const rememberMe = value["rememberMe"];

        if (
          !username || typeof username !== "string" ||
          !password || typeof password !== "string" ||
          (rememberMe && typeof rememberMe !== "string")
        ) {
          return c.redirect(this.prefixedUrl("/.auth?error=0"));
        }

        return { username, password, rememberMe };
      }),
      async (c) => {
        const req = c.req;
        const url = new URL(this.unprefixedUrl(req.url));
        const { username, password, rememberMe } = req.valid("form");

        const {
          user: expectedUser,
          pass: expectedPassword,
        } = this.options.auth!;

        if (lockoutTimer.isLocked()) {
          console.error("Authentication locked out, redirecting to auth page.");
          return c.redirect(this.prefixedUrl("/.auth?error=2"));
        }

        if (username === expectedUser && password === expectedPassword) {
          // Generate a JWT and set it as a cookie
          const jwt = rememberMe
            ? await this.jwtIssuer.createJWT({ username })
            : await this.jwtIssuer.createJWT(
              { username },
              authenticationExpirySeconds,
            );
          console.log("Successful auth");
          const inAWeek = new Date(
            Date.now() + authenticationExpirySeconds * 1000,
          );
          setCookie(c, authCookieName(url.host), jwt, {
            path: `${this.options.hostUrlPrefix ?? ""}/`,
            expires: inAWeek,
          });
          if (rememberMe) {
            setCookie(c, "refreshLogin", "true", {
              path: `${this.options.hostUrlPrefix ?? ""}/`,
              expires: inAWeek,
            });
          }
          const values = await req.parseBody();
          const from = values["from"];
          return c.redirect(
            this.prefixedUrl(typeof from === "string" ? from : "/"),
          );
        } else {
          console.error("Authentication failed, redirecting to auth page.");
          lockoutTimer.addCount();
          return c.redirect(this.prefixedUrl("/.auth?error=1"));
        }
      },
    ).all((c) => {
      return c.redirect(this.prefixedUrl("/.auth"));
    });

    // Simple ping health endpoint
    this.app.get("/.ping", (c) => {
      return c.text("OK", 200, {
        "Cache-Control": "no-cache",
      });
    });

    // Check auth on every other request
    this.app.use("*", async (c, next) => {
      if (!this.options.auth) {
        // Auth disabled in this config, skip
        return next();
      }
      const req = c.req;
      const url = new URL(this.unprefixedUrl(req.url));
      const path = this.unprefixedUrl(req.path);
      const host = url.host;
      const redirectToAuth = () => {
        // Try filtering api paths
        if (path.startsWith("/.") || path.endsWith(".md")) {
          return c.redirect(this.prefixedUrl("/.auth"), 401 as any);
        } else {
          return c.redirect(
            this.prefixedUrl(`/.auth?from=${path}`),
            302 as any,
          );
        }
      };
      if (!excludedPaths.includes(url.pathname)) {
        const authCookie = getCookie(c, authCookieName(host));

        if (!authCookie && this.options.auth?.authToken) {
          // Attempt Bearer Authorization based authentication
          const authHeader = req.header("Authorization");
          if (authHeader && authHeader.startsWith("Bearer ")) {
            const authToken = authHeader.slice("Bearer ".length);
            if (authToken === this.options.auth.authToken) {
              // All good, let's proceed
              this.refreshLogin(c, host);
              return next();
            } else {
              console.log(
                "Unauthorized token access, redirecting to auth page",
              );
              return c.text("Unauthorized", 401);
            }
          }
        }
        if (!authCookie) {
          console.log("Unauthorized access, redirecting to auth page");
          return redirectToAuth();
        }
        const { user: expectedUser } = this.options.auth!;

        try {
          const verifiedJwt = await this.jwtIssuer
            .verifyAndDecodeJWT(
              authCookie,
            );
          if (verifiedJwt.username !== expectedUser) {
            throw new Error("Username mismatch");
          }
        } catch (e: any) {
          console.error(
            "Error verifying JWT, redirecting to auth page",
            e.message,
          );
          return redirectToAuth();
        }
      }
      this.refreshLogin(c, host);
      return next();
    });

    // Fetch config
    this.app.get("/.config", (c) => {
      const clientConfig: BootConfig = {
        readOnly: this.options.readOnly,
        spaceFolderPath: this.options.pagesPath,
        indexPage: this.options.indexPage,
      };
      return c.json(clientConfig, 200, {
        "Cache-Control": "no-cache",
      });
    });

    // Shell command endpoint
    this.app.post("/.shell", (c) => {
      return handleShellEndpoint(
        c,
        this.shellBackend,
        this.options.readOnly,
      );
    });

    // HTTP Proxy endpoint
    const proxyPathRegex = "/.proxy/:uri{.+}";
    this.app.all(
      proxyPathRegex,
      async (c) => {
        const req = c.req;
        if (this.options.readOnly) {
          return c.text("Read only mode, no proxy allowed", 405);
        }

        // Get the full URL including query parameters
        const originalUrl = new URL(req.url);
        let url = req.param("uri")! + originalUrl.search;

        // Assume https unless this is localhost or an IP address
        if (
          url.startsWith("localhost") || url.match(/^\d+\./)
        ) {
          url = `http://${url}`;
        } else {
          url = `https://${url}`;
        }
        console.log("Proxying to", url);
        try {
          const safeRequestHeaders = new Headers();
          // List all headers
          for (
            const headerName of ["Authorization", "Accept", "Content-Type"]
          ) {
            if (req.header(headerName)) {
              safeRequestHeaders.set(
                headerName,
                req.header(headerName)!,
              );
            }
          }
          // List all headers starting with X-Proxy-Header-, remove the prefix and add to the safe headers
          for (const [key, value] of Object.entries(req.header())) {
            if (key.startsWith("x-proxy-header-")) {
              safeRequestHeaders.set(
                key.slice("x-proxy-header-".length), // corrected casing of header prefix
                value,
              );
            }
          }
          const body = await req.arrayBuffer();
          return fetch(url, {
            method: req.method,
            headers: safeRequestHeaders,
            body: body.byteLength > 0 ? body : undefined,
          });
        } catch (e: any) {
          console.error("Error fetching federated link", e);
          return c.text(e.message, 500);
        }
      },
    );
  }

  private refreshLogin(c: Context, host: string) {
    if (getCookie(c, "refreshLogin")) {
      const inAWeek = new Date(
        Date.now() + authenticationExpirySeconds * 1000,
      );
      const jwt = getCookie(c, authCookieName(host));
      if (jwt) {
        setCookie(c, authCookieName(host), jwt, {
          path: `${this.options.hostUrlPrefix ?? ""}/`,
          expires: inAWeek,
          // sameSite: "Strict",
          // httpOnly: true,
        });
        setCookie(c, "refreshLogin", "true", {
          path: `${this.options.hostUrlPrefix ?? ""}/`,
          expires: inAWeek,
        });
      }
    }
  }

  private buildFsRoutes(): Hono {
    const fsRoutes = new Hono();
    // File list
    fsRoutes.get("/", async (c) => {
      const req = c.req;
      if (req.header("X-Sync-Mode")) {
        // Only handle direct requests for a JSON representation of the file list
        const files = await this.spacePrimitives.fetchFileList();
        return c.json(files, 200, {
          "X-Space-Path": this.options.pagesPath,
        });
      } else {
        // Otherwise, redirect to the UI
        // The reason to do this is to handle authentication systems like Authelia nicely
        return c.redirect(this.prefixedUrl("/"));
      }
    });

    fsRoutes.get("/:path{.*}", this.handleGet.bind(this)).put(
      this.handlePut.bind(this),
    ).delete(this.handleDelete.bind(this)).options();

    return fsRoutes;
  }

  private async handleDelete(c: Context<any>) {
    const req = c.req;
    const name = req.param("path")!;
    if (this.options.readOnly) {
      return c.text("Read only mode, no writes allowed", 405);
    }
    console.log("Deleting file", name);
    try {
      await this.spacePrimitives.deleteFile(name);
      return c.text("OK");
    } catch (e: any) {
      console.error("Error deleting document", e);
      return c.text(e.message, 500);
    }
  }

  private async handlePut(c: Context<any>) {
    const req = c.req;
    const path = req.param("path")!;
    if (this.options.readOnly) {
      return c.text("Read only mode, no writes allowed", 405);
    }
    console.log("Writing file", path);

    const body = await req.arrayBuffer();

    try {
      const meta = await this.spacePrimitives.writeFile(
        path,
        new Uint8Array(body),
      );
      return c.text("OK", 200, fileMetaToHeaders(meta));
    } catch (err) {
      console.error("Write failed", err);
      return c.text("Write failed", 500);
    }
  }

  async handleGet(c: Context<any>) {
    const req = c.req;
    const name = req.param("path")!;

    try {
      if (req.header("X-Get-Meta")) {
        // Getting meta via GET request
        const fileData = await this.spacePrimitives.getFileMeta(
          name,
        );
        return c.text("", 200, fileMetaToHeaders(fileData));
      }
      const fileData = await this.spacePrimitives.readFile(name);
      const lastModifiedHeader = new Date(fileData.meta.lastModified)
        .toUTCString();
      if (
        req.header("If-Modified-Since") === lastModifiedHeader
      ) {
        return c.body(null, 304);
      }
      return c.body(new Uint8Array(fileData.data).buffer, 200, {
        ...fileMetaToHeaders(fileData.meta),
        "Last-Modified": lastModifiedHeader,
      });
    } catch (e: any) {
      console.error("Error GETting file", name, e.message);
      return c.notFound();
    }
  }

  private prefixedUrl(url: string): string {
    return applyUrlPrefix(url, this.options.hostUrlPrefix);
  }

  private unprefixedUrl(url: string): string {
    return removeUrlPrefix(url, this.options.hostUrlPrefix);
  }

  async ensureBasicPages() {
    await this.ensurePageWithContent(
      `${this.options.indexPage}.md`,
      INDEX_TEMPLATE,
    );

    const files = await this.spacePrimitives.fetchFileList();
    const hasConfig = files.some(
      (f) => f.name === "CONFIG.md" || f.name.endsWith("/CONFIG.md"),
    );
    if (!hasConfig) {
      await this.ensurePageWithContent("CONFIG.md", CONFIG_TEMPLATE);
    }
  }

  private async ensurePageWithContent(path: string, content: string) {
    try {
      // This will blow up if the page doesn't exist
      await this.spacePrimitives.getFileMeta(path);
    } catch (e: any) {
      if (e.message === notFoundError.message) {
        console.info(path, "page not found, creating...");
        await this.spacePrimitives.writeFile(
          path,
          new TextEncoder().encode(content),
        );
      } else {
        throw e;
      }
    }
  }
}