import type { ParsedXmlElement, ParsedXmlNode } from "@/worker/xml/parser";
import type { QName } from "@/worker/xml/namespaces";

export function splitXmlName(name: string): { prefix: string; localName: string } {
  const index = name.indexOf(":");
  if (index === -1) return { prefix: "", localName: name };
  return { prefix: name.slice(0, index), localName: name.slice(index + 1) };
}

function elementChildren(element: ParsedXmlElement): ParsedXmlElement[] {
  return element.children.filter((child): child is ParsedXmlElement => typeof child !== "string");
}

export function namespaceMap(element: ParsedXmlElement, parent: Record<string, string> = {}): Record<string, string> {
  const namespaces = { ...parent };
  for (const [name, value] of Object.entries(element.attributes)) {
    if (name === "xmlns") namespaces[""] = value;
    if (name.startsWith("xmlns:")) namespaces[name.slice("xmlns:".length)] = value;
  }
  return namespaces;
}

export function qnameForElement(element: ParsedXmlElement, namespaces = namespaceMap(element)): QName {
  const { prefix, localName } = splitXmlName(element.name);
  return { nsUri: namespaces[prefix] ?? "", localName };
}

export interface NamedXmlElement {
  element: ParsedXmlElement;
  qname: QName;
  namespaces: Record<string, string>;
}

export function namedElement(
  element: ParsedXmlElement,
  parentNamespaces: Record<string, string> = {},
): NamedXmlElement {
  const namespaces = namespaceMap(element, parentNamespaces);
  return { element, qname: qnameForElement(element, namespaces), namespaces };
}

export function namedElementChildren(
  element: ParsedXmlElement,
  parentNamespaces: Record<string, string>,
): NamedXmlElement[] {
  const namespaces = namespaceMap(element, parentNamespaces);
  return elementChildren(element).map((child) => namedElement(child, namespaces));
}

export function elementsByQName(
  element: ParsedXmlElement,
  qname: QName,
  parentNamespaces: Record<string, string> = {},
): NamedXmlElement[] {
  const matches: NamedXmlElement[] = [];
  for (const child of namedElementChildren(element, parentNamespaces)) {
    if (child.qname.nsUri === qname.nsUri && child.qname.localName === qname.localName) matches.push(child);
    matches.push(...elementsByQName(child.element, qname, child.namespaces));
  }
  return matches;
}

export function textContent(node: ParsedXmlNode): string {
  if (typeof node === "string") return node;
  return node.children.map(textContent).join("");
}

export function firstTextByQName(
  element: ParsedXmlElement,
  qname: QName,
  parentNamespaces: Record<string, string> = {},
): string | null {
  return elementsByQName(element, qname, parentNamespaces).at(0)?.element.children.map(textContent).join("") ?? null;
}