import { unified } from "npm:unified";
import remarkParse from "npm:remark-parse";
import remarkFrontmatter from "https://esm.sh/remark-frontmatter@4";
import { parse } from "https://deno.land/std@0.194.0/yaml/mod.ts";

const SILVERBULLET_SERVER = Deno.env.get("SILVERBULLET_SERVER");

export type Document = {
  name: string;
  lastModified: number;
  contentType: string;
  size: number;
  perm: string;
};

export function parseFrontmatter(yaml: string) {
  return parse(yaml);
}

export async function getDocuments(): Promise<Document[]> {
  const headers = new Headers();
  headers.append("Accept", "application/json");

  const response = await fetch(SILVERBULLET_SERVER + "/index.json", {
    headers: headers,
  });

  return response.json();
}

export async function getDocument(name: string): Promise<string> {
  const response = await fetch(SILVERBULLET_SERVER + "/" + name);
  return await response.text();
}

export function parseDocument(doc: string) {
  return unified()
    .use(remarkParse).use(remarkFrontmatter, ["yaml", "toml"])
    .parse(doc);
}

export type ParsedDocument = ReturnType<typeof parseDocument>;
export type DocumentChild = ParsedDocument["children"][number];

export function findRangeOfChildren(children: DocumentChild[]) {
  const firstChild = children[0];
  const lastChild = children.length > 1
    ? children[children.length - 1]
    : firstChild;

  const start = firstChild.position?.start.offset;
  const end = lastChild.position?.end.offset;

  if (typeof start !== "number" || typeof end !== "number") return;

  return [start, end];
}

export function getTextOfRange(children: DocumentChild[], text: string) {
  if (!children || children.length === 0) {
    return;
  }

  const range = findRangeOfChildren(children);
  if (!range) return;
  return text.substring(range[0], range[1]);
}

export function getTextOfChild(child: DocumentChild): string | undefined {
  if ("value" in child) return child.value;
  if ("children" in child) {
    return getTextOfChild(child.children[0]);
  }
  return;
}