paseo/packages/app/src/contexts/explorer-sidebar-animation-context.tsx

import {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useMemo,
  useRef,
  useState,
  type ReactNode,
} from "react";
import { useWindowDimensions } from "react-native";
import { useSharedValue, withTiming, Easing, type SharedValue } from "react-native-reanimated";
import { type GestureType } from "react-native-gesture-handler";
import { useIsCompactFormFactor } from "@/constants/layout";
import { useSidebarAnimation } from "@/contexts/sidebar-animation-context";
import { selectIsFileExplorerOpen, usePanelStore } from "@/stores/panel-store";
import {
  getRightSidebarAnimationTargets,
  shouldSyncSidebarAnimation,
} from "@/utils/sidebar-animation-state";

const ANIMATION_DURATION = 220;
const ANIMATION_EASING = Easing.bezier(0.25, 0.1, 0.25, 1);
// Keeps the overlay displayed long enough for the close animation to finish
// before React hides it.
const OVERLAY_CLOSE_GRACE_MS = 300;
interface ExplorerSidebarAnimationContextValue {
  translateX: SharedValue<number>;
  backdropOpacity: SharedValue<number>;
  windowWidth: number;
  animateToOpen: () => void;
  animateToClose: () => void;
  overlayVisible: boolean;
  setOverlayPeek: (peek: boolean) => void;
  isGesturing: SharedValue<boolean>;
  gestureAnimatingRef: React.MutableRefObject<boolean>;
  openGestureRef: React.MutableRefObject<GestureType | undefined>;
  closeGestureRef: React.MutableRefObject<GestureType | undefined>;
}

const ExplorerSidebarAnimationContext = createContext<ExplorerSidebarAnimationContextValue | null>(
  null,
);

export function ExplorerSidebarAnimationProvider({ children }: { children: ReactNode }) {
  const { startMobilePanelTransition, settleMobilePanel } = useSidebarAnimation();
  const { width: windowWidth } = useWindowDimensions();
  const isCompactLayout = useIsCompactFormFactor();
  const mobileView = usePanelStore((state) => state.mobileView);
  const isOpen = usePanelStore((state) =>
    selectIsFileExplorerOpen(state, { isCompact: isCompactLayout }),
  );

  // Right sidebar: closed = +windowWidth (off-screen right), open = 0
  const initialTargets = getRightSidebarAnimationTargets({ isOpen, windowWidth });
  const translateX = useSharedValue(initialTargets.translateX);
  const backdropOpacity = useSharedValue(initialTargets.backdropOpacity);
  const isGesturing = useSharedValue(false);
  const gestureAnimatingRef = useRef(false);
  const openGestureRef = useRef<GestureType | undefined>(undefined);
  const closeGestureRef = useRef<GestureType | undefined>(undefined);

  // React owns whether the overlay is displayed at all; the worklet owns its
  // motion. See the matching block in sidebar-animation-context.tsx for why
  // (Fabric re-applies stale animated props over committed props,
  // reanimated#9635).
  const [overlayPeek, setOverlayPeek] = useState(false);
  const overlayTarget = isOpen || overlayPeek;
  const [overlayVisible, setOverlayVisible] = useState(overlayTarget);
  useEffect(() => {
    if (overlayTarget) {
      setOverlayVisible(true);
      return;
    }
    const timer = setTimeout(() => setOverlayVisible(false), OVERLAY_CLOSE_GRACE_MS);
    return () => clearTimeout(timer);
  }, [overlayTarget]);

  // Track previous isOpen to detect changes
  const prevIsOpen = useRef(isOpen);
  const prevMobileView = useRef(mobileView);
  const prevWindowWidth = useRef(windowWidth);

  // Sync animation with store state changes (e.g., backdrop tap, programmatic open/close)
  useEffect(() => {
    const didStateChange = shouldSyncSidebarAnimation({
      previousIsOpen: prevIsOpen.current,
      nextIsOpen: isOpen,
      previousWindowWidth: prevWindowWidth.current,
      nextWindowWidth: windowWidth,
    });
    const didMobileViewChange = prevMobileView.current !== mobileView;
    const previousIsOpen = prevIsOpen.current;
    const previousMobileView = prevMobileView.current;
    const ownsMobileViewChange =
      previousMobileView === "file-explorer" || mobileView === "file-explorer";
    prevIsOpen.current = isOpen;
    prevMobileView.current = mobileView;
    prevWindowWidth.current = windowWidth;

    if (!didStateChange && !didMobileViewChange) {
      return;
    }

    if (gestureAnimatingRef.current) {
      gestureAnimatingRef.current = false;
      return;
    }

    // Don't animate if we're in the middle of a gesture - the gesture handler will handle it
    if (isGesturing.value) {
      return;
    }

    const targets = getRightSidebarAnimationTargets({ isOpen, windowWidth });

    if (previousIsOpen !== isOpen) {
      if (isOpen) {
        if (isCompactLayout) {
          startMobilePanelTransition("file-explorer");
        }
        translateX.value = withTiming(
          targets.translateX,
          {
            duration: ANIMATION_DURATION,
            easing: ANIMATION_EASING,
          },
          (finished) => {
            if (!finished) return;
            if (isCompactLayout) {
              settleMobilePanel("file-explorer");
            }
          },
        );
        backdropOpacity.value = withTiming(targets.backdropOpacity, {
          duration: ANIMATION_DURATION,
          easing: ANIMATION_EASING,
        });
        return;
      }

      if (isCompactLayout && mobileView === "agent") {
        startMobilePanelTransition("agent");
      }
      translateX.value = withTiming(
        targets.translateX,
        {
          duration: ANIMATION_DURATION,
          easing: ANIMATION_EASING,
        },
        (finished) => {
          if (!finished) return;
          if (isCompactLayout && mobileView === "agent") {
            settleMobilePanel("agent");
          }
        },
      );
      backdropOpacity.value = withTiming(targets.backdropOpacity, {
        duration: ANIMATION_DURATION,
        easing: ANIMATION_EASING,
      });
      return;
    }

    translateX.value = targets.translateX;
    backdropOpacity.value = targets.backdropOpacity;
    if (isCompactLayout && ownsMobileViewChange) {
      settleMobilePanel(mobileView);
    }
  }, [
    isOpen,
    mobileView,
    translateX,
    backdropOpacity,
    windowWidth,
    isGesturing,
    isCompactLayout,
    startMobilePanelTransition,
    settleMobilePanel,
  ]);

  const animateToOpen = useCallback(() => {
    "worklet";
    startMobilePanelTransition("file-explorer");
    translateX.value = withTiming(
      0,
      {
        duration: ANIMATION_DURATION,
        easing: ANIMATION_EASING,
      },
      (finished) => {
        if (!finished) return;
        settleMobilePanel("file-explorer");
      },
    );
    backdropOpacity.value = withTiming(1, {
      duration: ANIMATION_DURATION,
      easing: ANIMATION_EASING,
    });
  }, [translateX, backdropOpacity, startMobilePanelTransition, settleMobilePanel]);

  const animateToClose = useCallback(() => {
    "worklet";
    startMobilePanelTransition("agent");
    translateX.value = withTiming(
      windowWidth,
      {
        duration: ANIMATION_DURATION,
        easing: ANIMATION_EASING,
      },
      (finished) => {
        if (!finished) return;
        settleMobilePanel("agent");
      },
    );
    backdropOpacity.value = withTiming(0, {
      duration: ANIMATION_DURATION,
      easing: ANIMATION_EASING,
    });
  }, [translateX, backdropOpacity, windowWidth, startMobilePanelTransition, settleMobilePanel]);

  const value = useMemo<ExplorerSidebarAnimationContextValue>(
    () => ({
      translateX,
      backdropOpacity,
      windowWidth,
      animateToOpen,
      animateToClose,
      overlayVisible,
      setOverlayPeek,
      isGesturing,
      gestureAnimatingRef,
      openGestureRef,
      closeGestureRef,
    }),
    [
      translateX,
      backdropOpacity,
      windowWidth,
      animateToOpen,
      animateToClose,
      overlayVisible,
      isGesturing,
    ],
  );

  return (
    <ExplorerSidebarAnimationContext.Provider value={value}>
      {children}
    </ExplorerSidebarAnimationContext.Provider>
  );
}

export function useExplorerSidebarAnimation() {
  const context = useContext(ExplorerSidebarAnimationContext);
  if (!context) {
    throw new Error(
      "useExplorerSidebarAnimation must be used within ExplorerSidebarAnimationProvider",
    );
  }
  return context;
}

export function useExplorerSidebarAnimationOptional() {
  return useContext(ExplorerSidebarAnimationContext);
}