/**
 * Handles requests for route beneath a directory with a .spa file dropped in it.
 * @module
 */

import * as path from "@std/path";
import { PRECHECK, SERVER } from "../server.ts";
import { getCookies } from "@std/http/cookie";
import { load_html_with_ssi } from "./html.ts";

async function find_spa_file_root(request_path: string): Promise<string | undefined> {
	const cwd = Deno.cwd();

	const relative_path = path.relative(cwd, request_path);
	const path_elements = relative_path.split("/").slice(0, -1);

	do {
		const current_path = path.join(cwd, ...path_elements);

		try {
			const spa_static_file_stat = await Deno.stat(path.join(current_path, ".spa.static"));

			if (spa_static_file_stat.isFile) {
				return; // return nothing, we want files under this path to be handled as if static
			}
		} catch (error) {
			if (!(error instanceof Deno.errors.NotFound)) {
				throw error;
			}
		}

		try {
			const spa_file_stat = await Deno.stat(path.join(current_path, ".spa"));

			if (spa_file_stat.isFile) {
				return current_path;
			}
		} catch (error) {
			if (!(error instanceof Deno.errors.NotFound)) {
				throw error;
			}
		}
	} while (path_elements.pop());

	return undefined;
}

export type HTTP_METHOD = "GET" | "PUT" | "POST" | "DELETE" | "HEAD" | "OPTIONS";
export type HANDLER_METHOD = (
	request: Request,
	normalized_path: string,
	server: SERVER,
) => Promise<Response | undefined> | Response | undefined;
export const PRECHECKS: Partial<Record<HTTP_METHOD, PRECHECK[]>> = {};
export const HANDLERS: Partial<Record<HTTP_METHOD, HANDLER_METHOD>> = {
	HEAD: async (
		_request: Request,
		normalized_path: string,
		_server: SERVER,
	): Promise<Response | undefined> => {
		const spa_root = await find_spa_file_root(normalized_path);
		if (!spa_root) {
			return;
		}

		for await (const index_filename of ["index.html", "index.htm"]) {
			try {
				const index_file_path = path.join(spa_root, index_filename);
				const index_file_stat = await Deno.stat(index_file_path);

				if (index_file_stat.isFile) {
					return new Response("", {
						headers: {
							"Content-Type": "text/html",
							"Content-Length": `${index_file_stat.size}`,
							"Last-Modified": `${index_file_stat.mtime ?? index_file_stat.ctime}`,
						},
					});
				}
			} catch (error) {
				if (error instanceof Deno.errors.NotFound) {
					continue;
				}

				throw error;
			}
		}
	},

	GET: async (
		request: Request,
		normalized_path: string,
		_server: SERVER,
	): Promise<Response | undefined> => {
		const spa_root = await find_spa_file_root(normalized_path);
		if (!spa_root) {
			return;
		}

		for await (const index_filename of ["index.html", "index.htm"]) {
			try {
				const index_file_path = path.join(spa_root, index_filename);
				const index_file_stat = await Deno.stat(index_file_path);

				if (index_file_stat.isFile) {
					const processed: string = await load_html_with_ssi(index_file_path);
					return new Response(processed, {
						headers: {
							"Content-Type":
								request.headers.get("accept")?.indexOf("text/plain") !== -1
									? "text/plain"
									: "text/html",
						},
					});
				}
			} catch (error) {
				if (error instanceof Deno.errors.NotFound) {
					continue;
				}

				throw error;
			}
		}
	},

	OPTIONS: async (_request: Request, normalized_path: string): Promise<Response | undefined> => {
		const spa_root = await find_spa_file_root(normalized_path);
		if (!spa_root) {
			return;
		}

		for await (const index_filename of ["index.html", "index.htm"]) {
			try {
				const index_file_path = path.join(spa_root, index_filename);
				const index_file_stat = await Deno.stat(index_file_path);

				if (index_file_stat.isFile) {
					const allowed = ["GET", "HEAD", "OPTIONS"];

					return new Response("", {
						headers: {
							Allow: allowed.sort().join(","),
							"Access-Control-Allow-Origin":
								Deno.env.get("SERVERUS_ACCESS_CONTROL_ALLOW_ORIGIN") ?? "*",
						},
					});
				}
			} catch (error) {
				if (error instanceof Deno.errors.NotFound) {
					continue;
				}

				throw error;
			}
		}
	},
};

/**
 * Handles requests for static files.
 *
 * @param request The incoming HTTP request
 * @returns Either a response (a static file was requested and returned properly) or undefined if unhandled.
 */
export default async function handle_spa_files_in_path(
	request: Request,
	server: SERVER,
): Promise<Response | undefined> {
	const method: HTTP_METHOD = request.method.toUpperCase() as HTTP_METHOD;
	const handler: HANDLER_METHOD | undefined = HANDLERS[method];

	if (!handler) {
		return;
	}

	const url = new URL(request.url);
	const normalized_path = path.resolve(
		path.normalize(decodeURIComponent(url.pathname)).replace(/^\/+/, ""),
	);

	// if they're requesting something outside the working dir, just bail
	if (!normalized_path.startsWith(Deno.cwd())) {
		return;
	}

	const prechecks: PRECHECK[] = PRECHECKS[method] ?? [];

	const cookies: Record<string, string> = getCookies(request.headers);
	const query = Object.fromEntries(new URL(request.url).searchParams.entries());

	const metadata = {
		cookies,
		query,
	};

	for await (const precheck of prechecks) {
		const error_response: Response | undefined = await precheck(request, metadata);
		if (error_response) {
			return error_response;
		}
	}

	return await handler(request, normalized_path, server);
}