import { createReadStream, promises } from "node:fs";
import type { Context } from "koa";
import Router from "koa-router";
import type { ContentContext } from "./context.ts";

export async function renderVideo(ctx: Context, path: string) {
	const ext = path.trim().split(".").pop();
	if (ext === undefined) {
		// ctx.status = 404;
		console.error(`${path}:${ext}`);
		return;
	}
	ctx.response.type = ext;
	const range_text = ctx.request.get("range");
	const stat = await promises.stat(path);
	let start = 0;
	let end = 0;
	ctx.set("Last-Modified", new Date(stat.mtime).toUTCString());
	ctx.set("Date", new Date().toUTCString());
	ctx.set("Accept-Ranges", "bytes");
	if (range_text === "") {
		end = 1024 * 512;
		end = Math.min(end, stat.size - 1);
		if (start > end) {
			ctx.status = 416;
			return;
		}
		ctx.status = 200;
		ctx.length = stat.size;
		const stream = createReadStream(path);
		ctx.body = stream;
	} else {
		const m = range_text.match(/^bytes=(\d+)-(\d*)/);
		if (m === null) {
			ctx.status = 416;
			return;
		}
		start = Number.parseInt(m[1]);
		end = m[2].length > 0 ? Number.parseInt(m[2]) : start + 1024 * 1024;
		end = Math.min(end, stat.size - 1);
		if (start > end) {
			ctx.status = 416;
			return;
		}
		ctx.status = 206;
		ctx.length = end - start + 1;
		ctx.response.set("Content-Range", `bytes ${start}-${end}/${stat.size}`);
		ctx.body = createReadStream(path, {
			start: start,
			end: end,
		}); // inclusive range.
	}
}

export class VideoRouter extends Router<ContentContext> {
	constructor() {
		super();
		this.get("/", async (ctx, next) => {
			await renderVideo(ctx, ctx.state.location.path);
		});
		this.get("/thumbnail", async (ctx, next) => {
			await renderVideo(ctx, ctx.state.location.path);
		});
	}
}

export default VideoRouter;