import type { DavPatAuth } from "@/worker/auth/basic";
import { davError, emptyResponse, methodNotAllowed } from "@/worker/dav/http";
import type { SubjectRow } from "@/worker/db/d1/schema";
import type { AppContext } from "@/worker/types";

export interface DavRequestContext {
  c: AppContext;
  subject: SubjectRow;
  auth: DavPatAuth;
  pathname: string;
}

export interface DavArea {
  name: "files" | "caldav" | "carddav" | "discovery";
  allow: string;
  optionsHeaders: HeadersInit;
  matches(pathname: string): boolean;
  canUseMethod(auth: DavPatAuth, method: string): boolean;
  handle(context: DavRequestContext): Promise<Response>;
}

function allowedMethods(allow: string): Set<string> {
  return new Set(allow.split(",").map((method) => method.trim()));
}

export function findDavArea(pathname: string, areas: readonly DavArea[]): DavArea | null {
  return areas.find((area) => area.matches(pathname)) ?? null;
}

export function isMethodAllowed(area: DavArea, method: string): boolean {
  return allowedMethods(area.allow).has(method);
}

export function isExpensiveDavRequest(request: Request): boolean {
  if (request.method === "REPORT") return true;
  return request.method === "PROPFIND" && request.headers.get("depth")?.toLowerCase() === "infinity";
}

export function expensiveDavRequestArea(pathname: string): string {
  return pathname === "/files" || pathname.startsWith("/files/") ? "files" : (pathname.split("/")[1] ?? "unknown");
}

export async function dispatchDavArea(area: DavArea, context: DavRequestContext): Promise<Response> {
  const method = context.c.req.method;
  if (!area.canUseMethod(context.auth, method)) return davError(403, "PAT scope does not allow this method");
  if (method === "OPTIONS") return emptyResponse(204, area.optionsHeaders);
  if (!isMethodAllowed(area, method)) return methodNotAllowed(area.allow);
  return await area.handle(context);
}