import { APP_VERSION } from "./version";

// Detects whether a newer version has been pushed upstream by reading
// src/lib/version.ts from the Gitea repo's default branch and comparing its
// APP_VERSION to the running one. Self-contained — no OTM control plane needed.
// Reuses the same GITEA_* env as the suggestions module.
const GITEA_URL = process.env.GITEA_URL;
const GITEA_TOKEN = process.env.GITEA_TOKEN;
const GITEA_REPO = process.env.GITEA_REPO;
const GITEA_BRANCH = process.env.GITEA_BRANCH || "master";

export type UpdateStatus = {
  version: string;
  latest: string | null;
  updateAvailable: boolean;
};

/** Read APP_VERSION from src/lib/version.ts on the upstream branch. null on any failure. */
export async function fetchUpstreamVersion(): Promise<string | null> {
  if (!GITEA_URL || !GITEA_TOKEN || !GITEA_REPO) return null;
  try {
    const url = `${GITEA_URL}/api/v1/repos/${GITEA_REPO}/contents/src/lib/version.ts?ref=${GITEA_BRANCH}`;
    const res = await fetch(url, {
      headers: { Authorization: `token ${GITEA_TOKEN}` },
      cache: "no-store",
    });
    if (!res.ok) return null;
    const json = await res.json();
    if (!json?.content) return null;
    const decoded = Buffer.from(
      json.content,
      json.encoding === "base64" ? "base64" : "utf8"
    ).toString("utf8");
    const m = decoded.match(/APP_VERSION\s*=\s*["']([^"']+)["']/);
    return m ? m[1] : null;
  } catch {
    return null;
  }
}

/** Numeric dotted compare. -1 if a<b, 0 if equal, 1 if a>b. */
export function compareVersions(a: string, b: string): number {
  const pa = a.split(".").map((n) => parseInt(n, 10) || 0);
  const pb = b.split(".").map((n) => parseInt(n, 10) || 0);
  const len = Math.max(pa.length, pb.length);
  for (let i = 0; i < len; i++) {
    const d = (pa[i] || 0) - (pb[i] || 0);
    if (d !== 0) return d > 0 ? 1 : -1;
  }
  return 0;
}

export async function getUpdateStatus(): Promise<UpdateStatus> {
  const latest = await fetchUpstreamVersion();
  return {
    version: APP_VERSION,
    latest,
    updateAvailable: latest != null && compareVersions(latest, APP_VERSION) > 0,
  };
}