import { useSessionStream } from "../stream/useSessionStream";
import { useSessionStore } from "../store/sessionStore";
import { WidgetHost } from "./WidgetHost";
import { Transcript } from "./Transcript";
import { NavSessions } from "./NavSessions";
import { SteerInput, ComposerFooter } from "./SteerInput";
import { WorkflowBar } from "./WorkflowBar";
import { Button } from "../components/ui/button";
import { Toaster } from "../components/ui/sonner";
import { closeSession, listSessions, resumeSession } from "../api/sessions";
import type { SessionSummary } from "../api/types";
import { useQuery } from "@tanstack/react-query";
import { useRef, useState } from "react";

/**
 * The page is designed to live INSIDE the Omics Portal chrome (its left sidebar
 * + topbar) once embedded, so this shell intentionally has no left rail and no
 * top header of its own. The session rail sits on the RIGHT, mirroring the
 * portal's left sidebar, and the workflow phases ride a slim strip above the chat.
 */
export function AppShell() {
  const [activeSessionId, setActiveSessionId] = useState<string | null>(null);
  const { data: sessions = [] } = useQuery<SessionSummary[]>({
    queryKey: ["sessions"], queryFn: listSessions, refetchInterval: 10_000,
  });
  const composerRef = useRef<HTMLInputElement>(null);

  // The harness "holds the ball" whenever a session is live and no widget is
  // waiting on the human; once a widget appears, input is back in the user's court.
  const pendingWidget = useSessionStore((s) => s.pendingWidget);
  const resetSession = useSessionStore((s) => s.resetSession);
  const working = Boolean(activeSessionId) && !pendingWidget;

  useSessionStream(activeSessionId);

  function startNewSession() {
    resetSession();
    setActiveSessionId(null);
    requestAnimationFrame(() => composerRef.current?.focus());
  }

  async function stopSession() {
    if (!activeSessionId) return;
    try {
      await closeSession(activeSessionId);
    } finally {
      resetSession();
      setActiveSessionId(null);
    }
  }

  return (
    <div className="flex h-screen bg-background text-foreground">
      {/* Conversation column */}
      <div className="flex min-w-0 flex-1 flex-col">
        {activeSessionId && (
          <div className="shrink-0 border-b border-border/70 bg-background/80 px-6 py-2.5 backdrop-blur">
            <div className="mx-auto max-w-3xl">
              <WorkflowBar />
            </div>
          </div>
        )}

        <main className="flex-1 overflow-y-auto px-6 py-8">
          <div className="mx-auto flex max-w-3xl flex-col gap-6">
            {activeSessionId ? (
              <>
                <Transcript />
                <WidgetHost sessionId={activeSessionId} />
              </>
            ) : (
              <EmptyState />
            )}
          </div>
        </main>

        {/* Sticky composer: the box stays pinned while the conversation scrolls above. */}
        <div className="shrink-0 px-6 pb-6 pt-2">
          <div className="mx-auto max-w-3xl">
            <div className="rounded-2xl border border-input bg-card shadow-sm transition-colors focus-within:border-primary/40 focus-within:ring-3 focus-within:ring-ring/15">
              <div className="px-2.5 py-2">
                <SteerInput
                  sessionId={activeSessionId}
                  onSessionCreated={setActiveSessionId}
                  onStop={stopSession}
                  inputRef={composerRef}
                />
              </div>
              <ComposerFooter />
            </div>
          </div>
        </div>
      </div>

      {/* Right session rail — symmetric to the portal's left sidebar */}
      <aside className="flex w-[280px] shrink-0 flex-col border-l border-border bg-sidebar">
        <div className="relative px-4 pb-3 pt-5 text-center">
          {working && (
            <WorkingSpinner className="absolute left-4 top-[1.35rem]" />
          )}
          <h1 className="font-heading text-xl font-semibold leading-none tracking-tight text-foreground">
            Thoth<span className="text-primary">II</span>
          </h1>
          <p className="mt-1.5 text-[0.7rem] uppercase tracking-[0.14em] text-muted-foreground">
            Datamart Builder with
            <br />
            Human In The Loop
          </p>
        </div>

        <div className="flex flex-col gap-2 px-4 pb-3">
          <Button
            variant="default"
            size="sm"
            className="w-full"
            onClick={startNewSession}
          >
            New session
          </Button>
        </div>

        <div className="px-4 pb-1.5 pt-1">
          <span className="text-[0.7rem] font-bold uppercase tracking-[0.12em] text-primary">
            Sessions
          </span>
        </div>
        <div className="flex-1 overflow-y-auto px-2 pb-4">
          <NavSessions
            sessions={sessions}
            activeSessionId={activeSessionId}
            onOpenPanel={async (id) => { await resumeSession(id); setActiveSessionId(id); }}
            menuFor={() => null}
          />
        </div>
      </aside>

      <Toaster />
    </div>
  );
}

/** Brand-tinted spinner shown while the assistant/harness is working. */
function WorkingSpinner({ className }: { className?: string }) {
  return (
    <svg
      viewBox="0 0 24 24"
      fill="none"
      role="status"
      aria-label="Assistant is working"
      className={["size-4 animate-spin text-primary", className].filter(Boolean).join(" ")}
    >
      <circle cx="12" cy="12" r="9" stroke="currentColor" strokeWidth="3" opacity="0.2" />
      <path d="M21 12a9 9 0 0 0-9-9" stroke="currentColor" strokeWidth="3" strokeLinecap="round" />
    </svg>
  );
}

function EmptyState() {
  return (
    <div className="flex min-h-[60vh] flex-col items-center justify-center text-center">
      <span className="font-heading text-5xl font-semibold tracking-tight text-foreground">
        Thoth<span className="text-primary">II</span>
      </span>
      <p className="mt-4 max-w-md text-balance text-[0.95rem] leading-relaxed text-muted-foreground">
        Build datamarts from your data warehouse through a guided,
        human-in-the-loop workflow. Type your question in the box below to begin
        a session.
      </p>
    </div>
  );
}