import { davError, parseDepth } from "@/worker/dav/http";
import { parseIfHeader, type ParsedIfHeader } from "@/worker/dav/if-header";
import { maxXmlBodyBytes } from "@/worker/dav/limits";
import type { AppContext } from "@/worker/types";
import {
  parsePropfindXml,
  parseProppatchXml,
  type PropfindRequest,
  type ProppatchInstruction,
} from "@/worker/xml/dav-request";

export type DavReadResult<T> = { ok: true; value: T } | { ok: false; response: Response };

export interface DavConditionalHeaders {
  ifMatch: string | null;
  ifNoneMatch: string | null;
  ifHeader: ParsedIfHeader;
}

export function acceptedDavOrigins(c: AppContext): string[] {
  return [new URL(c.req.url).origin];
}

export function readDavConditionalHeaders(c: AppContext): DavReadResult<DavConditionalHeaders> {
  const parsedIf = parseIfHeader(c.req.header("if") ?? null);
  if (!parsedIf.ok) return { ok: false, response: davError(400, parsedIf.message) };
  return {
    ok: true,
    value: {
      ifMatch: c.req.header("if-match") ?? null,
      ifNoneMatch: c.req.header("if-none-match") ?? null,
      ifHeader: parsedIf.header,
    },
  };
}

export function readReportDepth(
  c: AppContext,
  fallback: "0" | "1" | "infinity",
): DavReadResult<"0" | "1" | "infinity"> {
  const depth = parseDepth(c.req.header("depth") ?? null, fallback);
  if (!depth) return { ok: false, response: davError(400, "REPORT Depth must be 0, 1, or infinity") };
  return { ok: true, value: depth };
}

export async function readCollectionPropfind(
  c: AppContext,
  resourceKind: string,
): Promise<DavReadResult<{ depth: "0" | "1"; request: PropfindRequest }>> {
  const depth = parseDepth(c.req.header("depth") ?? null, resourceKind === "object" ? "0" : "1");
  if (!depth) return { ok: false, response: davError(400, "Invalid Depth header") };

  try {
    return {
      ok: true,
      value: {
        // CalDAV/CardDAV collections are flat in dab. Treat valid Depth infinity
        // as the same bounded child listing as Depth 1 for client probes.
        depth: depth === "infinity" ? "1" : depth,
        request: parsePropfindXml(await c.req.text(), maxXmlBodyBytes(c.env)),
      },
    };
  } catch (cause) {
    return {
      ok: false,
      response: davError(400, cause instanceof Error ? cause.message : "Invalid PROPFIND body"),
    };
  }
}

export async function readCollectionProppatch(
  c: AppContext,
  _resourceKind?: unknown,
): Promise<DavReadResult<ProppatchInstruction[]>> {
  try {
    return { ok: true, value: parseProppatchXml(await c.req.text(), maxXmlBodyBytes(c.env)) };
  } catch (cause) {
    return {
      ok: false,
      response: davError(400, cause instanceof Error ? cause.message : "Invalid PROPPATCH body"),
    };
  }
}