/**
 * Checks that need every note at once: unique names, unique slugs and links
 * that resolve. The content service runs these on each change; the migration
 * runs them on its output.
 */
import { slugify, wikilinkTarget, wikilinksIn } from "./names.ts";
import { typeDef } from "./notes.ts";

export interface VaultNote {
  /** Path under the Site folder, like `Library/Books/Cosmere.md`. */
  path: string;
  type: string;
  data: Record<string, unknown>;
  body: string;
}

export interface VaultProblem {
  path: string;
  message: string;
}

/** The name Obsidian resolves a wikilink against: the file name without `.md`. */
export const linkName = (path: string) => path.replace(/^.*\//, "").replace(/\.md$/, "");

/** Every wikilink a note makes, from frontmatter and body. */
export function outgoingLinks(note: VaultNote): string[] {
  const found = new Set<string>();
  const visit = (v: unknown) => {
    if (typeof v === "string") {
      const t = wikilinkTarget(v);
      if (t) found.add(t);
    } else if (Array.isArray(v)) v.forEach(visit);
    else if (v && typeof v === "object") Object.values(v).forEach(visit);
  };
  visit(note.data);
  for (const t of wikilinksIn(note.body)) found.add(t);
  return [...found];
}

const IMAGE = /\.(jpe?g|png|gif|webp|svg|avif)$/i;

/**
 * Vault-wide problems. `attachments` lists attachment file names so image
 * links can be checked too.
 */
export function checkVault(notes: VaultNote[], attachments: string[] = []): VaultProblem[] {
  const problems: VaultProblem[] = [];
  const byName = new Map<string, VaultNote>();
  for (const n of notes) {
    const name = linkName(n.path).toLowerCase();
    const other = byName.get(name);
    if (other) problems.push({ path: n.path, message: `Same file name as ${other.path}, so links to it are ambiguous` });
    else byName.set(name, n);
  }

  const slugs = new Map<string, string>();
  for (const n of notes) {
    const def = typeDef(n.type);
    if (!def || def.singleton) continue;
    const slug = String(n.data.slug ?? slugify(String(n.data.title)));
    const key = `${n.type}:${slug}`;
    const other = slugs.get(key);
    if (other) problems.push({ path: n.path, message: `Slug "${slug}" is already used by ${other}` });
    else slugs.set(key, n.path);
  }

  const files = new Set(attachments.map((a) => a.toLowerCase()));
  for (const n of notes) {
    for (const target of outgoingLinks(n)) {
      const known = IMAGE.test(target) ? files.has(target.toLowerCase()) : byName.has(target.toLowerCase());
      if (!known) problems.push({ path: n.path, message: `Links to [[${target}]], which does not exist` });
    }
  }
  return problems;
}