// gitlab's own GitLab API client — its own code, living in the module (novox/hq ADR 0039). Ported
// from the hal sdk's shared GitLabClient, where a change to the GitLab API rebuilt everything; here
// it rebuilds only gitlab. This module's tools import it, and nothing outside gitlab does.
//
// gitlab is a tools-only, outbound-only integration with an external SaaS: it holds no service of
// its own, listens for nothing, and only ever calls out to a GitLab instance over its REST v4 API,
// authenticated with a personal/project access token (the PRIVATE-TOKEN header).
//
// The client is built lazily and NEVER throws at construction (the Servarr lesson): the runtime must
// come up and register every tool even with no valid token — the lab has no real GitLab. A missing
// URL or token surfaces only when a tool is actually invoked, as a clear error from that one call,
// not as a runtime that refuses to serve.

import { readFileSync } from "node:fs";

export class GitLabClient {
  constructor(
    /** The GitLab base URL, e.g. "https://gitlab.example.com". A public setting (config file). */
    private readonly url: string | undefined,
    /** The access token — gitlab's one secret (own-secret). */
    private readonly token: string | undefined,
  ) {}

  static fromEnv(env: NodeJS.ProcessEnv = process.env): GitLabClient {
    // The URL is a mesh's own fact, not this module's — a setting, merged into a config file the mesh
    // manages (novox/hq ADR 0046) under the key GITLAB_URL, read here. The token is the one secret and
    // stays an own-secret, read from its file. Env is honoured as a fallback for a hand-run instance.
    // Neither absence throws: the client still constructs, so every tool still registers and serves.
    const config = readConfig(env.MESH_GITLAB_CONFIG_FILE);
    const url = config.GITLAB_URL ?? env.MESH_GITLAB_URL ?? env.GITLAB_URL;
    const token = env.MESH_GITLAB_TOKEN ?? readSecret(env.MESH_GITLAB_TOKEN_FILE);
    return new GitLabClient(url, token);
  }

  /** Whether the module is configured enough to make a call. */
  configured(): boolean {
    return Boolean(this.url && this.token);
  }

  private baseUrl(): string {
    if (!this.url || !this.token) {
      throw new Error(
        "gitlab is not configured — set its URL in settings (GITLAB_URL) and its token as its " +
          "own-secret; until then it answers no calls",
      );
    }
    return this.url.replace(/\/+$/, "");
  }

  private encodeProject(id: number | string): string {
    return typeof id === "number" ? String(id) : encodeURIComponent(id);
  }

  private async request<T = unknown>(path: string, options: RequestInit = {}): Promise<T> {
    const res = await fetch(`${this.baseUrl()}/api/v4${path}`, {
      ...options,
      headers: {
        "Content-Type": "application/json",
        "PRIVATE-TOKEN": this.token!,
        ...(options.headers as Record<string, string>),
      },
    });
    if (!res.ok) {
      throw new Error(`GitLab API error ${res.status}: ${await res.text()}`);
    }
    if (res.status === 204) return null as T;
    return res.json() as Promise<T>;
  }

  private async requestText(path: string): Promise<string> {
    const res = await fetch(`${this.baseUrl()}/api/v4${path}`, {
      headers: { "PRIVATE-TOKEN": this.token! },
    });
    if (!res.ok) {
      throw new Error(`GitLab API error ${res.status}: ${await res.text()}`);
    }
    return res.text();
  }

  // --- Projects ---

  async listProjects(params: Record<string, string> = {}): Promise<unknown[]> {
    return this.request(`/projects?${new URLSearchParams(params).toString()}`);
  }

  async getProject(id: number | string): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(id)}`);
  }

  // --- Merge Requests ---

  async listMergeRequests(projectId: number | string, params: Record<string, string> = {}): Promise<unknown[]> {
    return this.request(`/projects/${this.encodeProject(projectId)}/merge_requests?${new URLSearchParams(params).toString()}`);
  }

  async getMergeRequest(projectId: number | string, mrIid: number): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/merge_requests/${mrIid}`);
  }

  async createMergeRequest(
    projectId: number | string,
    data: { source_branch: string; target_branch: string; title: string; description?: string },
  ): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/merge_requests`, {
      method: "POST",
      body: JSON.stringify(data),
    });
  }

  async approveMergeRequest(projectId: number | string, mrIid: number): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/merge_requests/${mrIid}/approve`, { method: "POST" });
  }

  async addMergeRequestNote(projectId: number | string, mrIid: number, body: string): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/merge_requests/${mrIid}/notes`, {
      method: "POST",
      body: JSON.stringify({ body }),
    });
  }

  // --- Pipelines ---

  async listPipelines(projectId: number | string, params: Record<string, string> = {}): Promise<unknown[]> {
    return this.request(`/projects/${this.encodeProject(projectId)}/pipelines?${new URLSearchParams(params).toString()}`);
  }

  async getPipeline(projectId: number | string, pipelineId: number): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/pipelines/${pipelineId}`);
  }

  async retryPipeline(projectId: number | string, pipelineId: number): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/pipelines/${pipelineId}/retry`, { method: "POST" });
  }

  async cancelPipeline(projectId: number | string, pipelineId: number): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/pipelines/${pipelineId}/cancel`, { method: "POST" });
  }

  async listPipelineJobs(projectId: number | string, pipelineId: number): Promise<unknown[]> {
    return this.request(`/projects/${this.encodeProject(projectId)}/pipelines/${pipelineId}/jobs`);
  }

  async getJobLog(projectId: number | string, jobId: number): Promise<string> {
    return this.requestText(`/projects/${this.encodeProject(projectId)}/jobs/${jobId}/trace`);
  }

  // --- Project variables ---

  async listProjectVariables(projectId: number | string): Promise<unknown[]> {
    return this.request(`/projects/${this.encodeProject(projectId)}/variables`);
  }

  async getProjectVariable(projectId: number | string, key: string): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/variables/${encodeURIComponent(key)}`);
  }

  async createProjectVariable(
    projectId: number | string,
    data: { key: string; value: string; protected?: boolean; masked?: boolean; environment_scope?: string },
  ): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/variables`, {
      method: "POST",
      body: JSON.stringify(data),
    });
  }

  async updateProjectVariable(
    projectId: number | string,
    key: string,
    data: { value: string; protected?: boolean; masked?: boolean; environment_scope?: string },
  ): Promise<unknown> {
    return this.request(`/projects/${this.encodeProject(projectId)}/variables/${encodeURIComponent(key)}`, {
      method: "PUT",
      body: JSON.stringify(data),
    });
  }

  async deleteProjectVariable(projectId: number | string, key: string): Promise<void> {
    await this.request(`/projects/${this.encodeProject(projectId)}/variables/${encodeURIComponent(key)}`, { method: "DELETE" });
  }

  // --- Group variables ---

  async listGroupVariables(groupId: number | string): Promise<unknown[]> {
    return this.request(`/groups/${this.encodeProject(groupId)}/variables`);
  }

  async getGroupVariable(groupId: number | string, key: string): Promise<unknown> {
    return this.request(`/groups/${this.encodeProject(groupId)}/variables/${encodeURIComponent(key)}`);
  }

  async createGroupVariable(
    groupId: number | string,
    data: { key: string; value: string; protected?: boolean; masked?: boolean; environment_scope?: string },
  ): Promise<unknown> {
    return this.request(`/groups/${this.encodeProject(groupId)}/variables`, {
      method: "POST",
      body: JSON.stringify(data),
    });
  }

  async updateGroupVariable(
    groupId: number | string,
    key: string,
    data: { value: string; protected?: boolean; masked?: boolean; environment_scope?: string },
  ): Promise<unknown> {
    return this.request(`/groups/${this.encodeProject(groupId)}/variables/${encodeURIComponent(key)}`, {
      method: "PUT",
      body: JSON.stringify(data),
    });
  }

  async deleteGroupVariable(groupId: number | string, key: string): Promise<void> {
    await this.request(`/groups/${this.encodeProject(groupId)}/variables/${encodeURIComponent(key)}`, { method: "DELETE" });
  }
}

function readSecret(path: string | undefined): string | undefined {
  if (!path) return undefined;
  try {
    return readFileSync(path, "utf8").trim();
  } catch {
    return undefined;
  }
}

interface Config {
  GITLAB_URL?: string;
}

/** The settings-managed config file (a JSON document the mesh merges settings into), holding the
 *  public GITLAB_URL setting. Absent or unparseable yields an empty config — the module then answers
 *  no calls until its URL and token are set, but still registers and serves every tool. */
function readConfig(path: string | undefined): Config {
  if (!path) return {};
  try {
    return JSON.parse(readFileSync(path, "utf8")) as Config;
  } catch {
    return {};
  }
}