/**
 * GitHub REST + GraphQL client on GH_PAT. Hand-rolled fetch, no SDK —
 * matching the repo's dependency-free automation rule.
 */

export interface GitHub {
  repo: string;
  rest(path: string, init?: RequestInit): Promise<unknown>;
  graphql(query: string, variables?: Record<string, unknown>): Promise<unknown>;
  list(path: string): AsyncGenerator<unknown, void, void>;
  /** Comment first, then close — a failed close still leaves a visible note. */
  closeIssue(issue: number, comment: string): Promise<void>;
  comment(issue: number, body: string): Promise<void>;
  react(commentId: number, content: string): Promise<void>;
}

const PER_PAGE = 100;

export function github(token: string, repo: string): GitHub {
  async function rest(path: string, init: RequestInit = {}): Promise<unknown> {
    const res = await fetch(`https://api.github.com${path}`, {
      ...init,
      headers: {
        accept: "application/vnd.github+json",
        authorization: `Bearer ${token}`,
        "user-agent": "srs-api",
        "x-github-api-version": "2022-11-28",
        ...(init.body ? { "content-type": "application/json" } : {}),
      },
    });
    if (!res.ok) {
      throw new Error(`${init.method ?? "GET"} ${path} -> ${res.status} ${await res.text()}`);
    }
    return res.status === 204 ? null : res.json();
  }

  async function graphql(
    query: string,
    variables: Record<string, unknown> = {},
  ): Promise<unknown> {
    const res = await fetch("https://api.github.com/graphql", {
      method: "POST",
      headers: {
        authorization: `Bearer ${token}`,
        "content-type": "application/json",
        "user-agent": "srs-api",
      },
      body: JSON.stringify({ query, variables }),
    });
    if (!res.ok) throw new Error(`graphql -> ${res.status} ${await res.text()}`);
    const payload = (await res.json()) as { data?: unknown; errors?: { message: string }[] };
    if (payload.errors?.length) throw new Error(payload.errors.map((e) => e.message).join("; "));
    return payload.data;
  }

  async function* list(path: string): AsyncGenerator<unknown, void, void> {
    const sep = path.includes("?") ? "&" : "?";
    for (let page = 1; ; page++) {
      const batch = await rest(`${path}${sep}per_page=${PER_PAGE}&page=${page}`);
      if (!Array.isArray(batch)) throw new Error(`unexpected ${path} payload: not an array`);
      yield* batch;
      if (batch.length < PER_PAGE) return;
    }
  }

  return {
    repo,
    rest,
    graphql,
    list,
    async closeIssue(issue, comment) {
      await rest(`/repos/${repo}/issues/${issue}/comments`, {
        method: "POST",
        body: JSON.stringify({ body: comment }),
      });
      await rest(`/repos/${repo}/issues/${issue}`, {
        method: "PATCH",
        body: JSON.stringify({ state: "closed", state_reason: "completed" }),
      });
    },
    async comment(issue, body) {
      await rest(`/repos/${repo}/issues/${issue}/comments`, {
        method: "POST",
        body: JSON.stringify({ body }),
      });
    },
    async react(commentId, content) {
      await rest(`/repos/${repo}/issues/comments/${commentId}/reactions`, {
        method: "POST",
        body: JSON.stringify({ content }),
      });
    },
  };
}