import { serveFile } from "jsr:@std/http/file-server";
import { type App, toValue } from "vue";
import { type Router } from "vue-router";
import { renderToString } from "vue/server-renderer";
import transpileResponse from "./transpile.ts";
import { DOMParser } from "jsr:@b-fuze/deno-dom";
import { join } from "jsr:@std/path/join";
import { exists } from "jsr:@std/fs";
import { type DJSSRContext } from "@/useDJSSRContext.ts";
import { type DJAPIResult, type DJAPIResultMap } from "@/api.ts";

const utf8Decoder = new TextDecoder("utf-8");

const parser = new DOMParser();

function appHeaderScript(params: { appstate: Record<string, unknown>; entryPath: string }) {
    return `<script type="importmap">
        {
            "imports": {
                "vue": "/deps/vue/dist/vue.esm-browser.prod.js",
                "vue-router": "/deps/vue-router/dist/vue-router.esm-browser.js",
                "vue/jsx-runtime": "/deps/vue/jsx-runtime/index.mjs",
                "@vue/devtools-api": "/deps/@vue/devtools-api/lib/esm/index.js",
                "@/": "/app/"
            }
        }
    </script>
    <script type="module"> 
        window.appstate = ${JSON.stringify(params.appstate)}; 
        import('${params.entryPath}');
    </script>`;
}

async function* siteEntries(path: string): AsyncGenerator<string> {
    for await (const dirEnt of Deno.readDir(path)) {
        if (dirEnt.isDirectory) {
            yield* siteEntries(join(path, dirEnt.name));
        } else if (dirEnt.name === "index_template.html") {
            yield path.split("/")[1] ?? "";
        }
    }
}

const publicFiles = siteEntries("public");
const sites: string[] = [];
for await (const path of publicFiles) {
    sites.push(path);
}

function getAPIResponse(apiReq: Request): Response {
    let jsonResponse: DJAPIResult | { error: string } | null = null;
    let status = 200;

    const pathname = URL.parse(apiReq.url)?.pathname;

    if (!pathname) {
        jsonResponse = { error: "Invalid Route" };
        status = 400;
    }

    if (!jsonResponse && pathname) {
        const apiPath = pathname.split("/api")[1];

        if (apiPath === "/rp-articles") {
            jsonResponse = [
                { name: "Koffein: ein vitamin-ähnlicher Nährstoff, oder Adaptogen", slug: "caffeine" },
                {
                    name: "TSH, Temperatur, Puls, und andere Indikatoren bei einer Schilddrüsenunterfunktion",
                    slug: "hypothyroidism",
                },
            ] satisfies DJAPIResultMap["/rp-articles"];
        }
    }

    const headers = new Headers();
    headers.set("Content-Type", "application/json");
    return new Response(JSON.stringify(jsonResponse), {
        status,
        headers,
    });
}

Deno.serve({
    port: 8080,
    hostname: "0.0.0.0",
    onListen({ port, hostname }) {
        console.log(`Listening on port http://${hostname}:${port}/`);
    },
}, async (req, _conn) => {
    let response: Response | null = null;

    if (req.method === "GET") {
        const pathname = URL.parse(req.url)?.pathname ?? "/";

        if (pathname.startsWith("/api/")) {
            response = getAPIResponse(req);
        }

        // Public/static files
        if (!response) {
            let filepath = join(".", "public", pathname);
            if (filepath.endsWith("/")) {
                filepath = join(filepath, "index.html");
            }
            if (await exists(filepath, { isFile: true })) {
                response = await serveFile(req, filepath);
            }
        }

        // NPM Vendor deps
        if (response === null && pathname.startsWith("/deps")) {
            response = await serveFile(req, `node_modules/${pathname.split("/deps")[1]}`);
        }

        // Transpile Code
        if (
            response === null &&
            pathname.startsWith("/app") &&
            (pathname.endsWith(".ts") || pathname.endsWith(".tsx")) &&
            !pathname.endsWith("server.ts")
        ) {
            response = await serveFile(req, "./" + pathname);
            response = await transpileResponse(response, req.url, pathname);
        }

        // SSR
        if (response === null) {
            const baseDirectoryName = pathname.split("/")[1] ?? "";
            if (sites.includes(baseDirectoryName)) {
                const appLocation = baseDirectoryName === "" ? "home" : baseDirectoryName;
                const siteTemplate = join("public", baseDirectoryName, "index_template.html");
                const siteEntry = join("app", appLocation, "server.ts");
                const clientEntry = join("@", appLocation, "client.ts");
                const { app, router } = (await import("./" + siteEntry)).default() as {
                    app: App;
                    router: Router | null;
                };
                app.provide("dom-parse", (innerHTML: string) => {
                    return parser.parseFromString(innerHTML, "text/html").documentElement;
                });
                const ssrContext: DJSSRContext = { registry: {}, head: { title: "" } };
                if (router) {
                    await router.replace(pathname.split("/generative-energy")[1]);
                    await router.isReady();
                }
                const rendered = await renderToString(app, ssrContext);
                const content = utf8Decoder.decode(await Deno.readFile(siteTemplate))
                    .replace(`<!-- SSR OUTLET -->`, rendered)
                    .replaceAll("%TITLE%", toValue(ssrContext.head?.title) ?? "Site")
                    .replace(
                        `<!-- SSR HEAD OUTLET -->`,
                        appHeaderScript({ appstate: ssrContext.registry, entryPath: clientEntry }),
                    );
                response = new Response(content, { headers: { "Content-Type": "text/html" } });
            }
        }
    } else {
        response = new Response("Only GET allowed.", { status: 500 });
    }

    return response ?? new Response("Not found.", { status: 404 });
});

Deno.addSignalListener("SIGINT", () => {
    console.info("Shutting down (received SIGINT)");
    Deno.exit();
});