export class Gitea {
  constructor(repositoryUrl, token, fetchImpl = fetch) {
    const url = new URL(repositoryUrl);
    this.origin = url.origin;
    this.base = `${url.origin}/api/v1/repos${url.pathname.replace(/\/$/, '')}`;
    this.token = token;
    this.fetch = fetchImpl;
  }

  async request(path, { method = 'GET', body, missing = false, raw = false } = {}) {
    const response = await this.fetch(`${this.base}${path}`, {
      method, redirect: 'error', signal: AbortSignal.timeout(60_000),
      headers: { Authorization: `token ${this.token}`, ...(body && !(body instanceof FormData) ? { 'Content-Type': 'application/json' } : {}) },
      body: body instanceof FormData ? body : body ? JSON.stringify(body) : undefined,
    });
    if (missing && response.status === 404) return null;
    if (!response.ok) throw new Error(`Gitea ${method} ${path}: HTTP ${response.status}`);
    if (raw) return Buffer.from(await response.arrayBuffer());
    return response.status === 204 ? null : response.json();
  }

  release(tag) { return this.request(`/releases/tags/${encodeURIComponent(tag)}`, { missing: true }); }
  tag(tag) { return this.request(`/tags/${encodeURIComponent(tag)}`, { missing: true }); }

  async releases() {
    const releases = [];
    for (let page = 1; ; page++) {
      const batch = await this.request(`/releases?limit=50&page=${page}`);
      releases.push(...batch);
      if (batch.length < 50) return releases;
    }
  }

  async asset(release, name) {
    const assets = await this.request(`/releases/${release.id}/assets`);
    const asset = assets.find(item => item.name === name);
    if (!asset) return null;
    let url = new URL(asset.browser_download_url);
    if (url.origin !== this.origin) throw new Error('Unerwartete Herkunft der Release-Datei.');
    for (let redirects = 0; redirects < 5; redirects++) {
      const response = await this.fetch(url.href, {
        redirect: 'manual', signal: AbortSignal.timeout(60_000),
        headers: url.origin === this.origin ? { Authorization: `token ${this.token}` } : {},
      });
      if ([301, 302, 303, 307, 308].includes(response.status)) {
        url = new URL(response.headers.get('location'), url);
        if (url.protocol !== 'https:') throw new Error('Unsicheres Download-Redirect.');
        continue;
      }
      if (!response.ok) throw new Error(`Release-Download: HTTP ${response.status}`);
      return Buffer.from(await response.arrayBuffer());
    }
    throw new Error('Zu viele Download-Redirects.');
  }

  async upload(release, name, data) {
    const assets = await this.request(`/releases/${release.id}/assets`);
    const existing = assets.find(item => item.name === name);
    if (existing) {
      const saved = await this.asset(release, name);
      if (!saved.equals(Buffer.from(data))) throw new Error(`Release-Datei ${name} existiert bereits mit anderem Inhalt.`);
      return;
    }
    const form = new FormData();
    form.append('attachment', new Blob([data]), name);
    await this.request(`/releases/${release.id}/assets?name=${encodeURIComponent(name)}`, { method: 'POST', body: form });
  }
}