import { useAtom, useAtomValue } from "jotai";
import {
  appOutputAtom,
  previewModeAtom,
  previewPanelKeyAtom,
  selectedAppIdAtom,
} from "../../atoms/appAtoms";
import { useLoadApp } from "@/hooks/useLoadApp";
import { CodeView } from "./CodeView";
import { PreviewIframe } from "./PreviewIframe";
import {
  Eye,
  Code,
  ChevronDown,
  ChevronUp,
  Logs,
  RefreshCw,
} from "lucide-react";
import { motion } from "framer-motion";
import { useEffect, useRef, useState, useCallback } from "react";
import { PanelGroup, Panel, PanelResizeHandle } from "react-resizable-panels";
import { Console } from "./Console";
import { useRunApp } from "@/hooks/useRunApp";

type PreviewMode = "preview" | "code";

interface PreviewHeaderProps {
  previewMode: PreviewMode;
  setPreviewMode: (mode: PreviewMode) => void;
  onRestart: () => void;
}

interface ConsoleHeaderProps {
  isOpen: boolean;
  onToggle: () => void;
  latestMessage?: string;
}

// Preview Header component with preview mode toggle
const PreviewHeader = ({
  previewMode,
  setPreviewMode,
  onRestart,
}: PreviewHeaderProps) => (
  <div className="flex items-center justify-between px-4 py-2 border-b border-border">
    <div className="relative flex space-x-2 bg-[var(--background-darkest)] rounded-md p-0.5">
      <button
        className="relative flex items-center space-x-1 px-3 py-1 rounded-md text-sm z-10"
        onClick={() => setPreviewMode("preview")}
      >
        {previewMode === "preview" && (
          <motion.div
            layoutId="activeIndicator"
            className="absolute inset-0 bg-(--background-lightest) shadow rounded-md -z-1"
            transition={{ type: "spring", stiffness: 500, damping: 35 }}
          />
        )}
        <Eye size={16} />
        <span>Preview</span>
      </button>
      <button
        className="relative flex items-center space-x-1 px-3 py-1 rounded-md text-sm z-10"
        onClick={() => setPreviewMode("code")}
      >
        {previewMode === "code" && (
          <motion.div
            layoutId="activeIndicator"
            className="absolute inset-0 bg-(--background-lightest) shadow rounded-md -z-1"
            transition={{ type: "spring", stiffness: 500, damping: 35 }}
          />
        )}
        <Code size={16} />
        <span>Code</span>
      </button>
    </div>
    <button
      onClick={onRestart}
      className="flex items-center space-x-1 px-3 py-1 rounded-md text-sm hover:bg-[var(--background-darkest)] transition-colors"
      title="Restart App"
    >
      <RefreshCw size={16} />
      <span>Restart</span>
    </button>
  </div>
);

// Console header component
const ConsoleHeader = ({
  isOpen,
  onToggle,
  latestMessage,
}: ConsoleHeaderProps) => (
  <div
    onClick={onToggle}
    className="flex items-start gap-2 px-4 py-1.5 border-t border-border cursor-pointer hover:bg-[var(--background-darkest)] transition-colors"
  >
    <Logs size={16} className="mt-0.5" />
    <div className="flex flex-col">
      <span className="text-sm font-medium">System Messages</span>
      {!isOpen && latestMessage && (
        <span className="text-xs text-gray-500 truncate max-w-[200px] md:max-w-[400px]">
          {latestMessage}
        </span>
      )}
    </div>
    <div className="flex-1" />
    {isOpen ? <ChevronDown size={16} /> : <ChevronUp size={16} />}
  </div>
);

// Main PreviewPanel component
export function PreviewPanel() {
  const [previewMode, setPreviewMode] = useAtom(previewModeAtom);
  const selectedAppId = useAtomValue(selectedAppIdAtom);
  const [isConsoleOpen, setIsConsoleOpen] = useState(false);
  const { runApp, stopApp, restartApp, error, loading, app } = useRunApp();
  const runningAppIdRef = useRef<number | null>(null);
  const key = useAtomValue(previewPanelKeyAtom);
  const appOutput = useAtomValue(appOutputAtom);

  const messageCount = appOutput.length;
  const latestMessage =
    messageCount > 0 ? appOutput[messageCount - 1]?.message : undefined;

  const handleRestart = useCallback(() => {
    restartApp();
  }, [restartApp]);

  useEffect(() => {
    const previousAppId = runningAppIdRef.current;

    // Check if the selected app ID has changed
    if (selectedAppId !== previousAppId) {
      // Stop the previously running app, if any
      if (previousAppId !== null) {
        console.debug("Stopping previous app", previousAppId);
        stopApp(previousAppId);
        // We don't necessarily nullify the ref here immediately,
        // let the start of the next app update it or unmount handle it.
      }

      // Start the new app if an ID is selected
      if (selectedAppId !== null) {
        console.debug("Starting new app", selectedAppId);
        runApp(selectedAppId); // Consider adding error handling for the promise if needed
        runningAppIdRef.current = selectedAppId; // Update ref to the new running app ID
      } else {
        // If selectedAppId is null, ensure no app is marked as running
        runningAppIdRef.current = null;
      }
    }

    // Cleanup function: This runs when the component unmounts OR before the effect runs again.
    // We only want to stop the app on actual unmount. The logic above handles stopping
    // when the appId changes. So, we capture the running appId at the time the effect renders.
    const appToStopOnUnmount = runningAppIdRef.current;
    return () => {
      if (appToStopOnUnmount !== null) {
        const currentRunningApp = runningAppIdRef.current;
        if (currentRunningApp !== null) {
          console.debug(
            "Component unmounting or selectedAppId changing, stopping app",
            currentRunningApp
          );
          stopApp(currentRunningApp);
          runningAppIdRef.current = null; // Clear ref on stop
        }
      }
    };
    // Dependencies: run effect when selectedAppId changes.
    // runApp/stopApp are stable due to useCallback.
  }, [selectedAppId, runApp, stopApp]);
  return (
    <div className="flex flex-col h-full">
      <PreviewHeader
        previewMode={previewMode}
        setPreviewMode={setPreviewMode}
        onRestart={handleRestart}
      />
      <div className="flex-1 overflow-hidden">
        <PanelGroup direction="vertical">
          <Panel id="content" minSize={30}>
            <div className="h-full overflow-y-auto">
              {previewMode === "preview" ? (
                <PreviewIframe
                  key={key}
                  loading={loading}
                  loadingErrorMessage={error?.message}
                />
              ) : (
                <CodeView loading={loading} error={error} app={app} />
              )}
            </div>
          </Panel>
          {isConsoleOpen && (
            <>
              <PanelResizeHandle className="h-1 bg-border hover:bg-gray-400 transition-colors cursor-row-resize" />
              <Panel id="console" minSize={10} defaultSize={30}>
                <div className="flex flex-col h-full">
                  <ConsoleHeader
                    isOpen={true}
                    onToggle={() => setIsConsoleOpen(false)}
                    latestMessage={latestMessage}
                  />
                  <Console />
                </div>
              </Panel>
            </>
          )}
        </PanelGroup>
      </div>
      {!isConsoleOpen && (
        <ConsoleHeader
          isOpen={false}
          onToggle={() => setIsConsoleOpen(true)}
          latestMessage={latestMessage}
        />
      )}
    </div>
  );
}
