import { getJson, getJsonSafe, normalizeBaseUrl, sendJson, shortSha, toIso } from "./http";
import {
  CALENDAR_PAGE_SIZE,
  calendarByPaging,
  calendarSince,
  type CommitCalendar,
} from "./calendar";
import { capReadme, decodeBase64, pickReadme, type RepoReadme } from "./readme";
import type {
  BranchInfo,
  CiInfo,
  CiState,
  CommitInfo,
  ConnectionCheck,
  CreatedIssue,
  GitClient,
  ProviderConfig,
  ReleaseInfo,
  RepoListItem,
  RepoRef,
  RepoSnapshotData,
  TagInfo,
  TicketInfo,
} from "./types";
import { bucketCommitActivity } from "./types";

/**
 * Gitea (und kompatible Forks wie Forgejo) – API v1.
 * Authentifizierung per "Authorization: token <PAT>".
 */
export class GiteaClient implements GitClient {
  readonly provider = "GITEA" as const;
  private readonly apiBase: string;
  private readonly token: string | null;

  constructor(config: ProviderConfig) {
    const base = normalizeBaseUrl(config.baseUrl);
    this.apiBase = `${base}/api/v1`;
    this.token = config.token;
  }

  private headers(): Record<string, string> {
    const headers: Record<string, string> = {};
    if (this.token) headers.Authorization = `token ${this.token}`;
    return headers;
  }

  private repoBase(ref: RepoRef): string {
    return `${this.apiBase}/repos/${encodeURIComponent(ref.owner)}/${encodeURIComponent(ref.name)}`;
  }

  async createIssue(
    ref: RepoRef,
    issue: { title: string; body?: string | null },
  ): Promise<CreatedIssue> {
    const angelegt = await sendJson<{ number: number; html_url?: string }>(
      `${this.repoBase(ref)}/issues`,
      "POST",
      { title: issue.title, body: issue.body ?? "" },
      { headers: this.headers() },
    );
    return { number: angelegt.number, url: angelegt.html_url ?? null };
  }

  async setIssueState(ref: RepoRef, number: number, open: boolean): Promise<void> {
    await sendJson(
      `${this.repoBase(ref)}/issues/${number}`,
      "PATCH",
      { state: open ? "open" : "closed" },
      { headers: this.headers() },
    );
  }

  async getIssueState(ref: RepoRef, number: number): Promise<"open" | "closed" | null> {
    const issue = await getJson<{ state?: string } | null>(
      `${this.repoBase(ref)}/issues/${number}`,
      { headers: this.headers(), allow404: true },
    );
    if (!issue?.state) return null;
    return issue.state === "closed" ? "closed" : "open";
  }

  async check(): Promise<ConnectionCheck> {
    try {
      const version = await getJsonSafe<{ version?: string }>(
        `${this.apiBase}/version`,
        {},
        { headers: this.headers() },
      );

      if (!this.token) {
        return {
          ok: true,
          message: `Instanz erreichbar${version.version ? ` (Gitea ${version.version})` : ""} – ohne Token nur oeffentliche Repos.`,
          user: null,
          version: version.version ?? null,
        };
      }

      const user = await getJson<{ login: string; full_name?: string }>(`${this.apiBase}/user`, {
        headers: this.headers(),
      });
      return {
        ok: true,
        message: `Verbunden als ${user.login}${version.version ? ` (Gitea ${version.version})` : ""}`,
        user: user.login,
        version: version.version ?? null,
      };
    } catch (error) {
      return { ok: false, message: error instanceof Error ? error.message : String(error) };
    }
  }

  async listRepos(query?: string): Promise<RepoListItem[]> {
    const url = this.token
      ? `${this.apiBase}/user/repos?limit=100`
      : `${this.apiBase}/repos/search?limit=50${query ? `&q=${encodeURIComponent(query)}` : ""}`;

    const raw = await getJson<GiteaRepo[] | { data: GiteaRepo[] }>(url, {
      headers: this.headers(),
    });
    const repos = Array.isArray(raw) ? raw : (raw?.data ?? []);
    const needle = query?.toLowerCase().trim();

    return repos
      .filter((repo) => !needle || repo.full_name.toLowerCase().includes(needle))
      .map((repo) => ({
        fullPath: repo.full_name,
        owner: repo.owner?.login ?? repo.full_name.split("/")[0] ?? "",
        name: repo.name,
        description: repo.description ?? null,
        htmlUrl: repo.html_url,
        defaultBranch: repo.default_branch ?? null,
        visibility: repo.private ? "private" : "public",
        updatedAt: toIso(repo.updated_at),
      }));
  }

  async fetchRepo(ref: RepoRef): Promise<RepoSnapshotData> {
    const base = `${this.apiBase}/repos/${encodeURIComponent(ref.owner)}/${encodeURIComponent(ref.name)}`;
    const headers = this.headers();

    const repo = await getJson<GiteaRepo>(base, { headers });

    const defaultBranch = repo.default_branch ?? "";

    const [branches, tags, commits, releases, languages, pulls, issues, status] =
      await Promise.all([
        getJsonSafe<GiteaBranch[]>(`${base}/branches?limit=50`, [], { headers }),
        getJsonSafe<GiteaTag[]>(`${base}/tags?limit=25`, [], { headers }),
        // 100 statt 15: die aelteren brauchen wir fuer die Aktivitaetskurve.
        getJsonSafe<GiteaCommit[]>(`${base}/commits?limit=100&stat=false`, [], { headers }),
        getJsonSafe<GiteaRelease[]>(`${base}/releases?limit=10`, [], { headers }),
        getJsonSafe<Record<string, number>>(`${base}/languages`, {}, { headers }),
        getJsonSafe<GiteaPull[]>(`${base}/pulls?state=open&limit=50`, [], { headers }),
        // type=issues, sonst kommen bei Gitea die Pull Requests mit.
        getJsonSafe<GiteaIssue[]>(`${base}/issues?state=open&type=issues&limit=50`, [], {
          headers,
        }),
        // Gitea meldet CI-Ergebnisse als Commit-Status. Das deckt Gitea
        // Actions und externe Systeme wie Woodpecker gleichermassen ab –
        // anders als ein reiner Actions-Endpunkt, den aeltere Instanzen
        // ohnehin nicht kennen.
        defaultBranch
          ? getJsonSafe<GiteaCombinedStatus>(
              `${base}/commits/${encodeURIComponent(defaultBranch)}/status`,
              {} as GiteaCombinedStatus,
              { headers },
            )
          : Promise.resolve({} as GiteaCombinedStatus),
      ]);

    const mappedBranches: BranchInfo[] = branches.map((branch) => ({
      name: branch.name,
      sha: branch.commit?.id ?? null,
      isDefault: branch.name === repo.default_branch,
      protected: Boolean(branch.protected),
      lastCommitAt: toIso(branch.commit?.timestamp),
      lastCommitMessage: branch.commit?.message?.split("\n")[0] ?? null,
      lastCommitAuthor: branch.commit?.author?.name ?? null,
      url: `${repo.html_url}/src/branch/${encodeURIComponent(branch.name)}`,
    }));

    const mappedTags: TagInfo[] = tags.map((tag) => ({
      name: tag.name,
      sha: tag.commit?.sha ?? tag.id ?? null,
      message: tag.message ?? null,
      date: toIso(tag.commit?.created),
      url: tag.zipball_url ? `${repo.html_url}/releases/tag/${encodeURIComponent(tag.name)}` : null,
    }));

    const mappedCommits: CommitInfo[] = commits.map((commit) => ({
      sha: commit.sha,
      shortSha: shortSha(commit.sha),
      message: commit.commit?.message?.split("\n")[0] ?? "",
      author: commit.commit?.author?.name ?? commit.author?.login ?? null,
      date: toIso(commit.commit?.author?.date ?? commit.created),
      url: commit.html_url ?? null,
    }));

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

    const mappedPulls: TicketInfo[] = pulls.map((pull) => ({
      number: pull.number,
      title: pull.title,
      author: pull.user?.login ?? null,
      createdAt: toIso(pull.created_at),
      url: pull.html_url ?? null,
      draft: Boolean(pull.draft),
      labels: (pull.labels ?? []).map((label) => label.name),
    }));

    const mappedIssues: TicketInfo[] = issues.map((issue) => ({
      number: issue.number,
      title: issue.title,
      author: issue.user?.login ?? null,
      createdAt: toIso(issue.created_at),
      url: issue.html_url ?? null,
      draft: false,
      labels: (issue.labels ?? []).map((label) => label.name),
    }));

    const latestStatus = status?.statuses?.[0];
    const ci: CiInfo | null =
      status?.state && status.state !== "" && status.statuses?.length
        ? {
            state: mapCommitStatus(status.state),
            name: latestStatus?.context ?? null,
            branch: defaultBranch || null,
            url: latestStatus?.target_url ?? null,
            finishedAt: toIso(latestStatus?.updated_at),
          }
        : null;

    return {
      fullName: repo.full_name,
      description: repo.description ?? null,
      defaultBranch: repo.default_branch ?? null,
      htmlUrl: repo.html_url,
      visibility: repo.private ? "private" : "public",
      stars: repo.stars_count ?? 0,
      forks: repo.forks_count ?? 0,
      openIssues: repo.open_issues_count ?? 0,
      openPullRequests: repo.open_pr_counter ?? pulls.length,
      sizeKb: repo.size ?? 0,
      pushedAt: toIso(repo.updated_at),
      branches: mappedBranches,
      tags: mappedTags,
      commits: mappedCommits.slice(0, 15),
      releases: mappedReleases,
      languages: languages ?? {},
      pullRequests: mappedPulls,
      issues: mappedIssues,
      ci,
      commitActivity: bucketCommitActivity(mappedCommits.map((commit) => commit.date)),
    };
  }

  /**
   * Gitea kennt keine Jahresstatistik ueber die API, also seitenweise.
   * `stat=false` und `verification=false` sparen dabei spuerbar Rechenzeit
   * auf der Gegenseite – gebraucht wird nur das Datum.
   */
  async fetchCommitCalendar(ref: RepoRef): Promise<CommitCalendar | null> {
    const base = `${this.apiBase}/repos/${encodeURIComponent(ref.owner)}/${encodeURIComponent(ref.name)}`;
    const seit = calendarSince().toISOString();

    // getJson und nicht getJsonSafe: ein Rate-Limit darf nicht als "keine
    // Daten" durchgehen – siehe maybeRefreshCalendar.
    return calendarByPaging(async (seite) => {
      const commits = await getJson<GiteaCommit[]>(
        `${base}/commits?limit=${CALENDAR_PAGE_SIZE}&page=${seite}` +
          `&stat=false&verification=false&files=false&since=${encodeURIComponent(seit)}`,
        { headers: this.headers() },
      );
      return commits.map((commit) => toIso(commit.commit?.author?.date));
    });
  }

  /**
   * Gitea kennt keinen README-Endpunkt. Erst das Wurzelverzeichnis
   * auflisten, dann die gefundene Datei holen – zwei Aufrufe.
   */
  async fetchReadme(ref: RepoRef): Promise<RepoReadme | null> {
    const base = `${this.apiBase}/repos/${encodeURIComponent(ref.owner)}/${encodeURIComponent(ref.name)}`;
    const headers = this.headers();

    const eintraege = await getJsonSafe<Array<{ name: string; type: string }>>(
      `${base}/contents`,
      [],
      { headers },
    );
    const name = pickReadme(
      eintraege.filter((eintrag) => eintrag.type === "file").map((eintrag) => eintrag.name),
    );
    if (!name) return null;

    const datei = await getJson<{
      content?: string;
      encoding?: string;
      path?: string;
      html_url?: string | null;
    }>(`${base}/contents/${encodeURIComponent(name)}`, { headers });
    if (!datei?.content || datei.encoding !== "base64") return null;

    const { content, truncated } = capReadme(decodeBase64(datei.content));
    return {
      content,
      path: datei.path ?? name,
      // html_url zeigt auf die Datei; fuer relative Links braucht es das
      // Verzeichnis darum herum.
      baseUrl: datei.html_url ? datei.html_url.replace(/\/[^/]*$/, "/") : null,
      truncated,
    };
  }
}

function mapCommitStatus(state: string): CiState {
  switch (state) {
    case "success":
      return "success";
    case "pending":
      return "running";
    case "failure":
    case "error":
      return "failure";
    default:
      return "pending";
  }
}

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

interface GiteaRepo {
  full_name: string;
  name: string;
  description: string | null;
  html_url: string;
  default_branch: string | null;
  private: boolean;
  stars_count: number;
  forks_count: number;
  open_issues_count: number;
  open_pr_counter?: number;
  size: number;
  updated_at: string | null;
  owner?: { login: string };
}

interface GiteaBranch {
  name: string;
  protected?: boolean;
  commit?: {
    id: string;
    message?: string;
    timestamp?: string;
    author?: { name?: string };
  };
}

interface GiteaTag {
  name: string;
  id?: string;
  message?: string | null;
  zipball_url?: string;
  commit?: { sha?: string; created?: string };
}

interface GiteaCommit {
  sha: string;
  html_url?: string;
  created?: string;
  author?: { login?: string } | null;
  commit?: {
    message?: string;
    author?: { name?: string; date?: string };
  };
}

interface GiteaRelease {
  name: string | null;
  tag_name: string;
  published_at: string | null;
  created_at: string | null;
  html_url: string | null;
  prerelease: boolean;
  draft: boolean;
}

interface GiteaLabel {
  name: string;
}

interface GiteaPull {
  number: number;
  title: string;
  html_url: string | null;
  created_at: string | null;
  draft?: boolean;
  user?: { login: string } | null;
  labels?: GiteaLabel[];
}

interface GiteaIssue {
  number: number;
  title: string;
  html_url: string | null;
  created_at: string | null;
  user?: { login: string } | null;
  labels?: GiteaLabel[];
}

interface GiteaCombinedStatus {
  state?: string;
  statuses?: Array<{
    context?: string;
    target_url?: string;
    updated_at?: string;
  }>;
}