import { getJson, getJsonSafe, normalizeBaseUrl, shortSha, toIso } from "./http";
import type {
  BranchInfo,
  CommitInfo,
  ConnectionCheck,
  GitClient,
  ProviderConfig,
  ReleaseInfo,
  RepoListItem,
  RepoRef,
  RepoSnapshotData,
  TagInfo,
} from "./types";

/**
 * GitLab – gitlab.com und selbst gehostete Instanzen (API v4).
 * Projekte werden ueber den URL-kodierten Pfad "gruppe%2Fprojekt" adressiert,
 * daher funktionieren auch verschachtelte Gruppen.
 */
export class GitLabClient implements GitClient {
  readonly provider = "GITLAB" as const;
  private readonly apiBase: string;
  private readonly token: string | null;

  constructor(config: ProviderConfig) {
    const base = normalizeBaseUrl(config.baseUrl || "https://gitlab.com");
    this.apiBase = `${base}/api/v4`;
    this.token = config.token;
  }

  private headers(): Record<string, string> {
    const headers: Record<string, string> = {};
    if (this.token) headers["PRIVATE-TOKEN"] = this.token;
    return headers;
  }

  async check(): Promise<ConnectionCheck> {
    try {
      if (!this.token) {
        await getJson(`${this.apiBase}/projects?per_page=1`, { headers: this.headers() });
        return { ok: true, message: "Erreichbar (ohne Token – nur oeffentliche Projekte).", user: null };
      }
      const user = await getJson<{ username: string; name?: string }>(`${this.apiBase}/user`, {
        headers: this.headers(),
      });
      return { ok: true, message: `Verbunden als ${user.username}`, user: user.username };
    } catch (error) {
      return { ok: false, message: error instanceof Error ? error.message : String(error) };
    }
  }

  async listRepos(query?: string): Promise<RepoListItem[]> {
    const search = query ? `&search=${encodeURIComponent(query)}` : "";
    const url = this.token
      ? `${this.apiBase}/projects?membership=true&per_page=100&order_by=last_activity_at${search}`
      : `${this.apiBase}/projects?per_page=50&order_by=last_activity_at${search}`;

    const projects = await getJson<GitLabProject[]>(url, { headers: this.headers() });
    return (projects ?? []).map((project) => {
      const path = project.path_with_namespace;
      const segments = path.split("/");
      return {
        fullPath: path,
        owner: segments.slice(0, -1).join("/"),
        name: segments[segments.length - 1] ?? project.name,
        description: project.description ?? null,
        htmlUrl: project.web_url,
        defaultBranch: project.default_branch ?? null,
        visibility: project.visibility ?? null,
        updatedAt: toIso(project.last_activity_at),
      };
    });
  }

  async fetchRepo(ref: RepoRef): Promise<RepoSnapshotData> {
    const path = [ref.owner, ref.name].filter(Boolean).join("/");
    const encoded = encodeURIComponent(path);
    const base = `${this.apiBase}/projects/${encoded}`;
    const headers = this.headers();

    const project = await getJson<GitLabProject>(`${base}?statistics=true`, { headers });

    const [branches, tags, commits, releases, languages, mergeRequests] = await Promise.all([
      getJsonSafe<GitLabBranch[]>(`${base}/repository/branches?per_page=50`, [], { headers }),
      getJsonSafe<GitLabTag[]>(`${base}/repository/tags?per_page=25`, [], { headers }),
      getJsonSafe<GitLabCommit[]>(`${base}/repository/commits?per_page=15`, [], { headers }),
      getJsonSafe<GitLabRelease[]>(`${base}/releases?per_page=10`, [], { headers }),
      getJsonSafe<Record<string, number>>(`${base}/languages`, {}, { headers }),
      getJsonSafe<GitLabMergeRequest[]>(`${base}/merge_requests?state=opened&per_page=100`, [], {
        headers,
      }),
    ]);

    const mappedBranches: BranchInfo[] = branches.map((branch) => ({
      name: branch.name,
      sha: branch.commit?.id ?? null,
      isDefault: Boolean(branch.default),
      protected: Boolean(branch.protected),
      lastCommitAt: toIso(branch.commit?.committed_date ?? branch.commit?.created_at),
      lastCommitMessage: branch.commit?.title ?? null,
      lastCommitAuthor: branch.commit?.author_name ?? null,
      url: branch.web_url ?? null,
    }));

    const mappedTags: TagInfo[] = tags.map((tag) => ({
      name: tag.name,
      sha: tag.commit?.id ?? null,
      message: tag.message ?? null,
      date: toIso(tag.commit?.committed_date ?? tag.commit?.created_at),
      url: `${project.web_url}/-/tags/${encodeURIComponent(tag.name)}`,
    }));

    const mappedCommits: CommitInfo[] = commits.map((commit) => ({
      sha: commit.id,
      shortSha: commit.short_id ?? shortSha(commit.id),
      message: commit.title ?? commit.message?.split("\n")[0] ?? "",
      author: commit.author_name ?? null,
      date: toIso(commit.committed_date ?? commit.created_at),
      url: commit.web_url ?? null,
    }));

    const mappedReleases: ReleaseInfo[] = releases.map((release) => ({
      name: release.name || release.tag_name,
      tag: release.tag_name,
      publishedAt: toIso(release.released_at ?? release.created_at),
      url: release._links?.self ?? null,
      prerelease: Boolean(release.upcoming_release),
      draft: false,
    }));

    return {
      fullName: project.path_with_namespace,
      description: project.description ?? null,
      defaultBranch: project.default_branch ?? null,
      htmlUrl: project.web_url,
      visibility: project.visibility ?? null,
      stars: project.star_count ?? 0,
      forks: project.forks_count ?? 0,
      openIssues: project.open_issues_count ?? 0,
      openPullRequests: mergeRequests.length,
      sizeKb: project.statistics?.repository_size
        ? Math.round(project.statistics.repository_size / 1024)
        : 0,
      pushedAt: toIso(project.last_activity_at),
      branches: mappedBranches,
      tags: mappedTags,
      commits: mappedCommits,
      releases: mappedReleases,
      languages: languages ?? {},
    };
  }
}

// ── API-Typen ──────────────────────────────────────────────────

interface GitLabProject {
  id: number;
  name: string;
  path_with_namespace: string;
  description: string | null;
  web_url: string;
  default_branch: string | null;
  visibility: string | null;
  star_count: number;
  forks_count: number;
  open_issues_count: number;
  last_activity_at: string | null;
  statistics?: { repository_size?: number };
}

interface GitLabCommitStub {
  id: string;
  short_id?: string;
  title?: string;
  message?: string;
  author_name?: string;
  committed_date?: string;
  created_at?: string;
  web_url?: string;
}

interface GitLabBranch {
  name: string;
  default?: boolean;
  protected?: boolean;
  web_url?: string;
  commit?: GitLabCommitStub;
}

interface GitLabTag {
  name: string;
  message: string | null;
  commit?: GitLabCommitStub;
}

type GitLabCommit = GitLabCommitStub;

interface GitLabRelease {
  name: string | null;
  tag_name: string;
  released_at: string | null;
  created_at: string | null;
  upcoming_release?: boolean;
  _links?: { self?: string };
}

interface GitLabMergeRequest {
  id: number;
}