import type { components, paths } from "./api.gen.js";

export type Schemas = components["schemas"];
export type User = Schemas["User"];
export type Project = Schemas["Project"];
export type Task = Schemas["Task"];
export type AgentSession = Schemas["AgentSession"];
export type InboxItem = Schemas["InboxItem"];
export type InboxResponse = Schemas["InboxResponse"];
export type InboxResponseCreate = Schemas["InboxResponseCreate"];
export type Attachment = Schemas["Attachment"];
export type ByreEvent = Schemas["Event"];
export type Status = Schemas["Status"];
export type NotificationPrefs = Schemas["NotificationPrefs"];
export type TurnRef = Schemas["TurnRef"];
export type AgentProcess = Schemas["AgentProcess"];
export type Zombie = Schemas["Zombie"];
export type ProtocolErrors = Schemas["ProtocolErrors"];
export type Snapshot = Schemas["Snapshot"];
export type Participant = Schemas["Participant"];
export type Focus = Schemas["Focus"];
export type TaskTab = Schemas["TaskTab"];
export type LeadNote = Schemas["LeadNote"];
export type WorkflowSummary = Schemas["WorkflowSummary"];

type Method = "get" | "post" | "put" | "delete";

type PathsWith<M extends Method> = {
  [P in keyof paths]: paths[P][M] extends { responses: unknown } ? P : never;
}[keyof paths];

type Op<P extends keyof paths, M extends Method> = NonNullable<paths[P][M]>;
type Params<O> = O extends { parameters: infer X } ? X : never;
type PathParams<O> = Params<O> extends { path: infer X } ? X : never;
type QueryParams<O> = Params<O> extends { query?: infer X } ? X : never;
type Body<O> = O extends { requestBody: { content: { "application/json": infer B } } }
  ? B
  : O extends { requestBody: { content: Record<`image/${string}`, unknown> } }
    ? Blob
    : never;
type Success<O> = O extends { responses: infer R } ? R[Extract<keyof R, 200 | 201 | 202>] : never;
type Result<O> = Success<O> extends { content: { "application/json": infer J } } ? J : never;

type Options<O> = {
  path?: PathParams<O>;
  query?: QueryParams<O>;
  body?: Body<O>;
  keepalive?: boolean;
};

export class ApiError extends Error {
  constructor(readonly status: number, message: string) {
    super(message);
  }
}

function target(path: string, opts: { path?: unknown; query?: unknown }): string {
  const pathParams = (opts.path ?? {}) as Record<string, unknown>;
  let url: string = path.replace(/\{(\w+)\}/g, (_, key: string) => {
    const value = pathParams[key];
    if (value === undefined) {
      throw new Error(`missing path parameter ${key} for ${path}`);
    }
    return encodeURIComponent(String(value));
  });

  const query = new URLSearchParams();
  for (const [key, value] of Object.entries((opts.query ?? {}) as Record<string, unknown>)) {
    if (value !== undefined) {
      query.set(key, String(value));
    }
  }
  if (query.size > 0) {
    url += `?${query}`;
  }
  return url;
}

export async function request<M extends Method, P extends PathsWith<M>>(
  method: M,
  path: P,
  opts: Options<Op<P, M>> = {},
): Promise<Result<Op<P, M>>> {
  const url = target(path, opts);
  const init: RequestInit = { method: method.toUpperCase(), keepalive: opts.keepalive ?? false };
  if (opts.body instanceof Blob) {
    init.headers = { "Content-Type": opts.body.type || "application/octet-stream" };
    init.body = opts.body;
  } else if (opts.body !== undefined) {
    init.headers = { "Content-Type": "application/json" };
    init.body = JSON.stringify(opts.body);
  }

  const res = await fetch(url, init);
  if (res.status === 204) {
    return undefined as Result<Op<P, M>>;
  }
  if (!res.headers.get("Content-Type")?.startsWith("application/json")) {
    const text = (await res.text()).trim();
    throw new ApiError(res.status, `${res.status} ${res.statusText}${text ? `: ${text}` : ""}`);
  }
  const data = await res.json();
  if (!res.ok) {
    throw new ApiError(res.status, (data as Schemas["Error"]).message);
  }
  return data as Result<Op<P, M>>;
}

export const get = <P extends PathsWith<"get">>(path: P, opts?: Options<Op<P, "get">>) => request("get", path, opts);
export const post = <P extends PathsWith<"post">>(path: P, opts?: Options<Op<P, "post">>) => request("post", path, opts);
export const put = <P extends PathsWith<"put">>(path: P, opts?: Options<Op<P, "put">>) => request("put", path, opts);
export const del = <P extends PathsWith<"delete">>(path: P, opts?: Options<Op<P, "delete">>) => request("delete", path, opts);

export function socket<P extends PathsWith<"get">>(path: P, opts: Options<Op<P, "get">>): WebSocket {
  const ws = new WebSocket(`${location.protocol === "https:" ? "wss:" : "ws:"}//${location.host}${target(path, opts)}`);
  ws.binaryType = "arraybuffer";
  return ws;
}

const staleAfterMs = 40_000;
const retryAfterMs = 2_000;

export function subscribe(
  after: number,
  filter: { task_id?: string; lead?: boolean },
  onEvent: (ev: ByreEvent) => void,
  onState: (connected: boolean) => void,
  onReady: () => void,
): () => void {
  let last = after;
  let heard = Date.now();
  let source: EventSource | undefined;
  let retry = 0;

  const connect = () => {
    clearTimeout(retry);
    source?.close();
    heard = Date.now();
    const query = new URLSearchParams({ after: String(last) });
    if (filter.task_id) {
      query.set("task_id", filter.task_id);
    }
    if (filter.lead) {
      query.set("lead", "true");
    }
    const s = new EventSource(`/api/events?${query}`);
    source = s;
    s.onopen = () => {
      heard = Date.now();
      onState(true);
    };
    s.onerror = () => {
      onState(false);
      if (s.readyState === EventSource.CLOSED) {
        retry = setTimeout(connect, retryAfterMs);
      }
    };
    s.addEventListener("ping", () => {
      heard = Date.now();
    });
    s.addEventListener("ready", () => {
      heard = Date.now();
      onReady();
    });
    s.onmessage = (msg: MessageEvent<string>) => {
      heard = Date.now();
      const ev = JSON.parse(msg.data) as ByreEvent;
      if (ev.seq > last) {
        last = ev.seq;
      }
      onEvent(ev);
    };
  };

  const check = () => {
    if (Date.now() - heard < staleAfterMs) {
      return;
    }
    onState(false);
    connect();
  };

  const onVisible = () => {
    if (document.visibilityState === "visible") {
      check();
    }
  };

  const interval = setInterval(check, 5_000);
  addEventListener("online", connect);
  document.addEventListener("visibilitychange", onVisible);
  connect();
  return () => {
    clearInterval(interval);
    clearTimeout(retry);
    removeEventListener("online", connect);
    document.removeEventListener("visibilitychange", onVisible);
    source?.close();
  };
}