import { readSse } from "./sse";
import type {
  AgentsResponse,
  AuditPage,
  BusEvent,
  ConversationInfo,
  ConversationSummary,
  EntriesPage,
  HistoryMessage,
  JobsResponse,
  LimitsResponse,
  MemoryFile,
  MemoryTree,
  SessionsResponse,
  TokenRow,
  UsageGroup,
  UsageResponse,
} from "./types";

const TRAILING_SLASHES = /\/+$/;

export class ApiError extends Error {
  status: number;
  body: unknown;

  constructor(status: number, message: string, body: unknown) {
    super(message);
    this.status = status;
    this.body = body;
  }
}

function messageOf(status: number, body: unknown): string {
  if (body && typeof body === "object") {
    const record = body as Record<string, unknown>;
    for (const key of ["error", "detail"]) {
      if (typeof record[key] === "string") {
        return record[key] as string;
      }
    }
  }
  if (typeof body === "string" && body) {
    return body;
  }
  return `HTTP ${status}`;
}

async function bodyOf(response: Response): Promise<unknown> {
  const text = await response.text();
  try {
    return JSON.parse(text);
  } catch {
    return text;
  }
}

export type Params = Record<string, string | number | boolean | undefined>;

function query(params?: Params): string {
  if (!params) {
    return "";
  }
  const search = new URLSearchParams();
  for (const [key, value] of Object.entries(params)) {
    if (value !== undefined && value !== "") {
      search.set(key, String(value));
    }
  }
  const text = search.toString();
  return text ? `?${text}` : "";
}

export interface ClientOptions {
  onUnauthorized?: () => Promise<string | null>;
}

// One client per signed-in session: the gateway origin, a bearer, and a
// hook that refreshes the bearer once when the gateway rotated it.
export class ApiClient {
  base: string;
  token: string;
  private readonly onUnauthorized?: () => Promise<string | null>;

  constructor(base: string, token: string, options: ClientOptions = {}) {
    this.base = base.replace(TRAILING_SLASHES, "");
    this.token = token;
    this.onUnauthorized = options.onUnauthorized;
  }

  url(path: string, params?: Params): string {
    return `${this.base}${path}${query(params)}`;
  }

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

  private async request<T>(
    method: string,
    path: string,
    body?: unknown,
    params?: Params,
    retried = false
  ): Promise<T> {
    const response = await fetch(this.url(path, params), {
      body: body === undefined ? undefined : JSON.stringify(body),
      headers: this.headers(
        body === undefined ? {} : { "Content-Type": "application/json" }
      ),
      method,
    });
    if (response.status === 401 && !retried && this.onUnauthorized) {
      const token = await this.onUnauthorized();
      if (token) {
        this.token = token;
        return this.request<T>(method, path, body, params, true);
      }
    }
    if (!response.ok) {
      const payload = await bodyOf(response);
      throw new ApiError(
        response.status,
        messageOf(response.status, payload),
        payload
      );
    }
    if (response.status === 204) {
      return undefined as T;
    }
    return (await response.json()) as T;
  }

  get<T>(path: string, params?: Params): Promise<T> {
    return this.request<T>("GET", path, undefined, params);
  }

  post<T>(path: string, body?: unknown): Promise<T> {
    return this.request<T>("POST", path, body ?? {});
  }

  patch<T>(path: string, body?: unknown): Promise<T> {
    return this.request<T>("PATCH", path, body ?? {});
  }

  async stream(
    path: string,
    onEvent: (event: BusEvent) => void,
    signal: AbortSignal
  ): Promise<void> {
    const response = await fetch(this.url(path), {
      headers: this.headers({ Accept: "text/event-stream" }),
      signal,
    });
    if (!response.ok) {
      const payload = await bodyOf(response);
      throw new ApiError(
        response.status,
        messageOf(response.status, payload),
        payload
      );
    }
    await readSse(response, onEvent, signal);
  }

  agents(): Promise<AgentsResponse> {
    return this.get("/api/agents");
  }

  conversations(params?: {
    kind?: string;
    status?: string;
    limit?: number;
  }): Promise<{ conversations: ConversationSummary[] }> {
    return this.get("/api/conversations", params);
  }

  conversation(id: string): Promise<ConversationInfo> {
    return this.get(`/api/conversations/${id}`);
  }

  history(id: string): Promise<{ id: string; messages: HistoryMessage[] }> {
    return this.get(`/api/conversations/${id}/history`);
  }

  entries(
    id: string,
    params?: { subpath?: string; offset?: number; limit?: number }
  ): Promise<EntriesPage> {
    return this.get(`/api/conversations/${id}/entries`, params);
  }

  postMessage(
    id: string,
    text: string,
    origin = "panel"
  ): Promise<{ id: string; item: number; status: string }> {
    return this.post(`/api/conversations/${id}/messages`, { origin, text });
  }

  inject(
    id: string,
    text: string,
    urgency: "normal" | "urgent",
    origin = "panel"
  ): Promise<{ id: string; item: number; priority: string }> {
    return this.post(`/api/conversations/${id}/inject`, {
      origin,
      text,
      urgency,
    });
  }

  answer(
    id: string,
    questionId: string,
    answer: string
  ): Promise<{ id: string; question_id: string }> {
    return this.post(`/api/conversations/${id}/answer`, {
      answer,
      question_id: questionId,
    });
  }

  branch(
    id: string,
    body: { seed?: string; text?: string; title?: string; window?: number }
  ): Promise<ConversationInfo> {
    return this.post(`/api/conversations/${id}/branch`, body);
  }

  merge(
    id: string
  ): Promise<{ id: string; status: string; fork: string; text: string }> {
    return this.post(`/api/conversations/${id}/merge`);
  }

  bind(
    id: string,
    frontend: string,
    externalId: string,
    visible: boolean
  ): Promise<ConversationInfo> {
    return this.post(`/api/conversations/${id}/bind`, {
      external_id: externalId,
      frontend,
      visible,
    });
  }

  setFlags(
    id: string,
    flags: Record<string, unknown>
  ): Promise<ConversationSummary> {
    return this.patch(`/api/conversations/${id}/flags`, flags);
  }

  update(
    id: string,
    body: { status?: string; title?: string }
  ): Promise<ConversationSummary> {
    return this.patch(`/api/conversations/${id}`, body);
  }

  spawn(body: {
    kind: string;
    agent?: string;
    seed?: string;
    text?: string;
    title?: string;
  }): Promise<ConversationInfo> {
    return this.post("/api/conversations", body);
  }

  sessions(): Promise<SessionsResponse> {
    return this.get("/api/sessions");
  }

  jobs(): Promise<JobsResponse> {
    return this.get("/api/jobs");
  }

  runJob(name: string): Promise<{ job: number | null }> {
    return this.post(`/api/jobs/${encodeURIComponent(name)}/run`);
  }

  cancelJob(id: number): Promise<{ cancelled: number }> {
    return this.request("DELETE", `/api/jobs/queue/${id}`);
  }

  usage(params: {
    since?: string;
    until?: string;
    hours?: number;
    group_by: UsageGroup;
  }): Promise<UsageResponse> {
    return this.get("/api/usage", params);
  }

  limits(): Promise<LimitsResponse> {
    return this.get("/api/limits");
  }

  memory(): Promise<MemoryTree> {
    return this.get("/api/memory");
  }

  memoryFile(path: string): Promise<MemoryFile> {
    return this.get("/api/memory/file", { path });
  }

  tokens(includeRevoked = false): Promise<{ tokens: TokenRow[] }> {
    return this.get("/api/tokens", {
      include_revoked: includeRevoked ? 1 : undefined,
    });
  }

  createToken(
    name: string,
    scope: string
  ): Promise<{ token: TokenRow; plaintext: string }> {
    return this.post("/api/tokens", { name, scope });
  }

  revokeToken(id: number): Promise<{ id: number; revoked: boolean }> {
    return this.post(`/api/tokens/${id}/revoke`);
  }

  audit(params?: { before?: number; limit?: number }): Promise<AuditPage> {
    return this.get("/api/audit", params);
  }
}