import { fileTypeFromBuffer } from "file-type";
import hljs from "highlight.js";
import { decrypt } from "./crypto";
import { getMode, humanFileSize, isValidUTF8, setupModeRadios } from "./shared";

async function showContent(content: Uint8Array, filetype: string) {
	const filesize = document.getElementById("filesize") as HTMLDivElement | null;
	if (filesize) {
		filesize.textContent = `size: ${humanFileSize(content.byteLength)}`;
	}

	const mediaBox = document.getElementById("mediabox") as HTMLDivElement | null;
	if (!mediaBox) {
		console.error("Missing mediaBox element.");
		return;
	}
	let preview: HTMLElement = document.createElement("div");
	preview.textContent = "This file can't be previewed";
	if (isValidUTF8(content) && filetype !== "blob") {
		preview = document.createElement("pre");
		if (filetype === "none") {
			preview.textContent = new TextDecoder().decode(content);
		} else {
			preview.innerHTML = hljs.highlight(
				new TextDecoder("utf-8").decode(content),
				{ language: filetype },
			).value;
		}
	} else {
		const filetype = await fileTypeFromBuffer(content);
		if (filetype) {
			const blob = new Blob([content as BlobPart], { type: filetype.mime });
			const url = URL.createObjectURL(blob);
			if (filetype.mime.startsWith("audio/")) {
				preview = document.createElement("audio");
				preview.setAttribute("controls", "");
				preview.setAttribute("src", url);
			} else if (filetype.mime.startsWith("video/")) {
				preview = document.createElement("video");
				preview.setAttribute("controls", "");
				preview.setAttribute("src", url);
			} else if (filetype.mime.startsWith("image/")) {
				preview = document.createElement("img");
				preview.setAttribute("src", url);
			}
		}
	}
	mediaBox.innerHTML = "";
	mediaBox.appendChild(preview);
}

let encrypted: Uint8Array | undefined;
let content: Uint8Array;
let filetype: string;
let filename: string;

const uuid = window.location.pathname
	.split("/")
	.filter((x) => x !== "")
	.reverse()[0];

// Remembers the client-side password for this file for the rest of the browser
// session, mirroring the server-side password cookie so the prompt only appears
// once per session.
const PASSWORD_KEY = `zbin-pw-${uuid}`;

// Called from the overlay form's onsubmit. In server mode we let the form POST
// the password to /set-cookie (native submit). In client mode we intercept,
// fetch the still-encrypted bytes, and decrypt locally so the password never
// leaves the browser.
function onPasswordSubmit(): boolean {
	if (getMode("decrypt_mode") === "server") {
		return true;
	}
	const passwordInput = document.getElementById(
		"password",
	) as HTMLInputElement | null;
	const passwordLabel = document.getElementById(
		"password-label",
	) as HTMLLabelElement | null;
	if (passwordInput) {
		void decryptClientSide(passwordInput.value, passwordLabel);
	}
	return false;
}

async function decryptClientSide(
	password: string,
	passwordLabel: HTMLLabelElement | null,
): Promise<boolean> {
	if (!encrypted) {
		const response = await fetch(`/raw/${uuid}?ignore_password=true`);
		encrypted = new Uint8Array(await response.arrayBuffer());
		filetype = response.headers.get("filetype") || "none";
		filename = response.headers.get("filename") || "";
	}
	try {
		content = await decrypt(encrypted, password);
	} catch (_e) {
		if (passwordLabel) passwordLabel.textContent = "Incorrect password";
		return false;
	}
	sessionStorage.setItem(PASSWORD_KEY, password);
	document.getElementById("decrypt-overlay")?.remove();
	const downloadForm = document.getElementById(
		"download-form",
	) as HTMLFormElement | null;
	downloadForm?.setAttribute("action", "");
	downloadForm?.addEventListener("submit", (e) => {
		e.preventDefault();
		const blob = new Blob([content as BlobPart]);
		const url = URL.createObjectURL(blob);
		const link = document.createElement("a");
		link.download = filename;
		link.href = url;
		link.click();
	});
	showContent(content, filetype);
	return true;
}

setupModeRadios("decrypt_mode");

// If we already decrypted this file this session, auto-decrypt with the stored
// password instead of prompting again. Drop a stale password if it no longer works.
const savedPassword = sessionStorage.getItem(PASSWORD_KEY);
if (savedPassword) {
	decryptClientSide(savedPassword, null).then((ok) => {
		if (!ok) sessionStorage.removeItem(PASSWORD_KEY);
	});
}

Object.assign(window, { onPasswordSubmit });