"use client";
import { createContext, useCallback, useContext, useMemo, useRef, useState, type ReactNode } from "react";
import { isApiError } from "./api";

export type ToastKind = "info" | "success" | "warning" | "error";
export interface ToastItem {
  id: number;
  kind: ToastKind;
  title: string;
  detail?: string;
  requestId?: string | null;
}

interface ToastCtx {
  toasts: ToastItem[];
  push: (t: Omit<ToastItem, "id">) => void;
  dismiss: (id: number) => void;
  error: (e: unknown, fallback?: string) => void;
  success: (title: string, detail?: string) => void;
  info: (title: string, detail?: string) => void;
}

const Ctx = createContext<ToastCtx | null>(null);

export function ToastProvider({ children }: { children: ReactNode }) {
  const [toasts, setToasts] = useState<ToastItem[]>([]);
  const seq = useRef(0);

  const dismiss = useCallback((id: number) => setToasts((t) => t.filter((x) => x.id !== id)), []);
  const push = useCallback(
    (t: Omit<ToastItem, "id">) => {
      const id = ++seq.current;
      setToasts((prev) => [...prev.slice(-4), { ...t, id }]);
      const ttl = t.kind === "error" ? 9000 : 4500;
      window.setTimeout(() => dismiss(id), ttl);
    },
    [dismiss],
  );
  const error = useCallback(
    (e: unknown, fallback = "Request failed") => {
      if (isApiError(e)) {
        push({ kind: "error", title: `${e.message}`, detail: `${e.code} · HTTP ${e.status}`, requestId: e.request_id });
      } else if (e instanceof Error) {
        push({ kind: "error", title: fallback, detail: e.message });
      } else {
        push({ kind: "error", title: fallback });
      }
    },
    [push],
  );
  const success = useCallback((title: string, detail?: string) => push({ kind: "success", title, detail }), [push]);
  const info = useCallback((title: string, detail?: string) => push({ kind: "info", title, detail }), [push]);

  const value = useMemo(() => ({ toasts, push, dismiss, error, success, info }), [toasts, push, dismiss, error, success, info]);
  return <Ctx.Provider value={value}>{children}</Ctx.Provider>;
}

export function useToast(): ToastCtx {
  const c = useContext(Ctx);
  if (!c) throw new Error("useToast outside ToastProvider");
  return c;
}