export type SourceCredit = {
  title: string;
  license: string;
  uri?: string;
  attribution?: string;
  licenseUrl?: string;
  retrievedAt?: string;
  originSha?: string;
  modificationNotice?: string;
};

const LICENSE_URLS: Record<string, string> = {
  "CC0-1.0": "https://creativecommons.org/publicdomain/zero/1.0/",
  "CC-BY-4.0": "https://creativecommons.org/licenses/by/4.0/",
  "CC-BY-NC-4.0": "https://creativecommons.org/licenses/by-nc/4.0/",
  MIT: "https://opensource.org/license/mit",
};

const ATTRIBUTION_LICENSES = new Set(["CC-BY-4.0", "CC-BY-NC-4.0", "MIT"]);

export function uniqueOriginNotices(sources: SourceCredit[]): SourceCredit[] {
  const seen = new Set<string>();
  const notices: SourceCredit[] = [];
  for (const source of sources) {
    if (!source.attribution?.trim()) continue;
    const key = [source.attribution, source.license, source.licenseUrl ?? "", source.originSha ?? "", source.modificationNotice ?? ""].join("\n");
    if (seen.has(key)) continue;
    seen.add(key);
    notices.push(source);
  }
  return notices;
}

export function attributionGaps(source: SourceCredit): string[] {
  const gaps: string[] = [];
  if (!source.license) gaps.push("license");
  if (!source.title.trim()) gaps.push("title");
  if (!source.uri?.trim()) gaps.push("uri");
  if (ATTRIBUTION_LICENSES.has(source.license) && !source.attribution?.trim()) gaps.push("attribution");
  if (source.license === "CC-BY-4.0" || source.license === "CC-BY-NC-4.0") {
    if (source.licenseUrl !== LICENSE_URLS[source.license]) gaps.push("licenseUrl");
    if (!source.retrievedAt?.trim()) gaps.push("retrievedAt");
    if (!source.originSha?.trim()) gaps.push("originSha");
    if (!source.modificationNotice?.trim()) gaps.push("modificationNotice");
  }
  return gaps;
}