import * as React from 'react';
import { useRef, useState, useMemo, useCallback } from 'react';
import { StyleSheet, View } from 'react-native';
import {
  PinchGestureHandler,
  PinchGestureHandlerGestureEvent,
  State,
  TapGestureHandler,
  TapGestureHandlerStateChangeEvent,
} from 'react-native-gesture-handler';
import { Navigation, NavigationFunctionComponent } from 'react-native-navigation';
import type { CameraDevice, CameraDeviceFormat, CameraProps, CameraRuntimeError, PhotoFile, VideoFile } from 'react-native-vision-camera';
import { Camera, frameRateIncluded, sortDevices, sortFormatsByResolution, filterFormatsByAspectRatio } from 'react-native-vision-camera';
import { useIsScreenFocused } from './hooks/useIsScreenFocused';
import { CONTENT_SPACING, MAX_ZOOM_FACTOR, SAFE_AREA_PADDING } from './Constants';
import Reanimated, { Extrapolate, interpolate, useAnimatedGestureHandler, useAnimatedProps, useSharedValue } from 'react-native-reanimated';
import { useEffect } from 'react';
import { useIsForeground } from './hooks/useIsForeground';
import { StatusBarBlurBackground } from './views/StatusBarBlurBackground';
import { CaptureButton } from './views/CaptureButton';
import { PressableOpacity } from './views/PressableOpacity';
import MaterialIcon from 'react-native-vector-icons/MaterialCommunityIcons';
import IonIcon from 'react-native-vector-icons/Ionicons';
import { useSelector } from 'pipestate';
import { FpsSelector } from './state/selectors';

// @ts-expect-error The <Camera> types are a bit tricky since they're using Unions. I'll try to flatten those out in a future PR.
const ReanimatedCamera = Reanimated.createAnimatedComponent(Camera);
Reanimated.addWhitelistedNativeProps({
  zoom: true,
});

const SCALE_FULL_ZOOM = 3;
const BUTTON_SIZE = 40;

export const App: NavigationFunctionComponent = ({ componentId }) => {
  const camera = useRef<Camera>(null);
  const [isCameraInitialized, setIsCameraInitialized] = useState(false);
  const zoom = useSharedValue(0);
  const isPressingButton = useSharedValue(false);

  // check if camera page is active
  const isFocussed = useIsScreenFocused(componentId);
  const isForeground = useIsForeground();
  const isActive = isFocussed && isForeground;

  const [cameraPosition, setCameraPosition] = useState<'front' | 'back'>('back');
  const [enableHdr, setEnableHdr] = useState(false);
  const [flash, setFlash] = useState<'off' | 'on'>('off');
  const [enableNightMode, setEnableNightMode] = useState(false);

  // camera format settings
  const [devices, setDevices] = useState<CameraDevice[]>([]); // All available camera devices, sorted by "best device" (descending)
  const device = useMemo<CameraDevice | undefined>(() => devices.find((d) => d.position === cameraPosition), [cameraPosition, devices]);
  const formats = useMemo<CameraDeviceFormat[]>(() => {
    if (device?.formats == null) return [];
    const filtered = filterFormatsByAspectRatio(device.formats);
    return filtered.sort(sortFormatsByResolution);
  }, [device?.formats]);

  //#region Memos
  const [targetFps] = useSelector(FpsSelector);
  console.log(`Target FPS: ${targetFps}`);
  const fps = useMemo(() => {
    if (enableNightMode && !device?.supportsLowLightBoost) {
      // User has enabled Night Mode, but Night Mode is not natively supported, so we simulate it by lowering the frame rate.
      return 30;
    }

    const supportsHdrAtHighFps = formats.some((f) => f.supportsVideoHDR && f.frameRateRanges.some((r) => frameRateIncluded(r, targetFps)));
    if (enableHdr && !supportsHdrAtHighFps) {
      // User has enabled HDR, but HDR is not supported at targetFps.
      return 30;
    }

    const supportsHighFps = formats.some((f) => f.frameRateRanges.some((r) => frameRateIncluded(r, targetFps)));
    if (!supportsHighFps) {
      // targetFps is not supported by any format.
      return 30;
    }
    // If nothing blocks us from using it, we default to targetFps.
    return targetFps;
  }, [device?.supportsLowLightBoost, enableHdr, enableNightMode, formats, targetFps]);

  const supportsCameraFlipping = useMemo(() => devices.some((d) => d.position === 'back') && devices.some((d) => d.position === 'front'), [devices]);
  const supportsFlash = device?.hasFlash ?? false;
  const supportsHdr = useMemo(() => formats.some((f) => f.supportsVideoHDR), [formats]);
  const canToggleNightMode = enableNightMode
    ? true // it's enabled so you have to be able to turn it off again
    : (device?.supportsLowLightBoost ?? false) || fps > 30; // either we have native support, or we can lower the FPS
  //#endregion

  const format = useMemo(() => {
    let result = formats;
    if (enableHdr) {
      // We only filter by HDR capable formats if HDR is set to true.
      // Otherwise we ignore the `supportsVideoHDR` property and accept formats which support HDR `true` or `false`
      result = result.filter((f) => f.supportsVideoHDR);
    }

    // find the first format that includes the given FPS
    return result.find((f) => f.frameRateRanges.some((r) => frameRateIncluded(r, fps)));
  }, [formats, fps, enableHdr]);

  //#region Animated Zoom
  const formatMaxZoom = format?.maxZoom ?? 1;
  const maxZoomFactor = Math.min(formatMaxZoom, MAX_ZOOM_FACTOR);
  const neutralZoom = device?.neutralZoom ?? 0;
  const neutralZoomScaled = (neutralZoom / maxZoomFactor) * formatMaxZoom;
  const maxZoomScaled = (1 / formatMaxZoom) * maxZoomFactor;

  const cameraAnimatedProps = useAnimatedProps<Partial<CameraProps>>(
    () => ({
      zoom: interpolate(zoom.value, [0, neutralZoomScaled, 1], [0, neutralZoom, maxZoomScaled], Extrapolate.CLAMP),
    }),
    [maxZoomScaled, neutralZoom, neutralZoomScaled, zoom],
  );
  //#endregion

  //#region Callbacks
  const setIsPressingButton = useCallback(
    (_isPressingButton: boolean) => {
      isPressingButton.value = _isPressingButton;
    },
    [isPressingButton],
  );
  // Camera callbacks
  const onError = useCallback((error: CameraRuntimeError) => {
    console.error(error);
  }, []);
  const onInitialized = useCallback(() => {
    console.log('Camera initialized!');
    setIsCameraInitialized(true);
  }, []);
  const onMediaCaptured = useCallback(async (media: PhotoFile | VideoFile, type: 'photo' | 'video') => {
    console.log(`Media captured! ${JSON.stringify(media)}`);
    await Navigation.showModal({
      component: {
        name: 'Media',
        passProps: {
          type: type,
          path: media.path,
        },
      },
    });
  }, []);
  const onFlipCameraPressed = useCallback(() => {
    setCameraPosition((p) => (p === 'back' ? 'front' : 'back'));
  }, []);
  const onHdrSwitchPressed = useCallback(() => {
    setEnableHdr((h) => !h);
  }, []);
  const onFlashPressed = useCallback(() => {
    setFlash((f) => (f === 'off' ? 'on' : 'off'));
  }, []);
  const onNightModePressed = useCallback(() => {
    setEnableNightMode((n) => !n);
  }, []);
  const onSettingsPressed = useCallback(() => {
    Navigation.push(componentId, { component: { name: 'Settings' } });
  }, [componentId]);
  //#endregion

  //#region Tap Gesture
  const onDoubleTapGesture = useCallback(
    ({ nativeEvent: event }: TapGestureHandlerStateChangeEvent) => {
      // TODO: (MARC) Allow switching camera (back <-> front) while recording and stich videos together!
      if (isPressingButton.value) return;
      switch (event.state) {
        case State.END:
          // on double tap
          onFlipCameraPressed();
          break;
        default:
          break;
      }
    },
    [isPressingButton, onFlipCameraPressed],
  );
  //#endregion

  //#region Effects
  useEffect(() => {
    const loadDevices = async (): Promise<void> => {
      try {
        const availableCameraDevices = await Camera.getAvailableCameraDevices();
        console.log(`Devices: ${availableCameraDevices.map((d) => d.name).join(', ')}`);
        const sortedDevices = availableCameraDevices.sort(sortDevices);
        console.debug(`Devices (sorted): ${sortedDevices.map((d) => d.name).join(', ')}`);
        setDevices(sortedDevices);
      } catch (e) {
        console.error('Failed to get available devices!', e);
      }
    };
    loadDevices();
  }, []);
  useEffect(() => {
    // Run everytime the neutralZoomScaled value changes. (reset zoom when device changes)
    zoom.value = neutralZoomScaled;
  }, [neutralZoomScaled, zoom]);

  useEffect(() => {
    // Run everytime the camera gets set to isActive = false. (reset zoom when tab switching)
    if (!isActive) zoom.value = neutralZoomScaled;
  }, [neutralZoomScaled, isActive, zoom]);
  //#endregion

  //#region Pinch to Zoom Gesture
  // The gesture handler maps the linear pinch gesture (0 - 1) to an exponential curve since a camera's zoom
  // function does not appear linear to the user. (aka zoom 0.1 -> 0.2 does not look equal in difference as 0.8 -> 0.9)
  const onPinchGesture = useAnimatedGestureHandler<PinchGestureHandlerGestureEvent, { startZoom?: number }>({
    onStart: (_, context) => {
      context.startZoom = zoom.value;
    },
    onActive: (event, context) => {
      // we're trying to map the scale gesture to a linear zoom here
      const startZoom = context.startZoom ?? 0;
      const scale = interpolate(event.scale, [1 - 1 / SCALE_FULL_ZOOM, 1, SCALE_FULL_ZOOM], [-1, 0, 1], Extrapolate.CLAMP);
      zoom.value = interpolate(scale, [-1, 0, 1], [0, startZoom, 1], Extrapolate.CLAMP);
    },
  });
  //#endregion

  if (device != null && format != null) {
    console.log(
      `Re-rendering camera page with ${isActive ? 'active' : 'inactive'} camera. ` +
        `Device: "${device.name}" (${format.photoWidth}x${format.photoHeight} @ ${fps}fps)`,
    );
  } else {
    console.log('re-rendering camera page without active camera');
  }

  // TODO: Implement camera flipping (back <-> front) while recording and stich the videos together
  // TODO: iOS: Use custom video data stream output to manually process the data and write the MOV/MP4 for more customizability.
  return (
    <View style={styles.container}>
      {device != null && (
        <PinchGestureHandler onGestureEvent={onPinchGesture} enabled={isActive}>
          <Reanimated.View style={StyleSheet.absoluteFill}>
            <TapGestureHandler onHandlerStateChange={onDoubleTapGesture} numberOfTaps={2}>
              <ReanimatedCamera
                ref={camera}
                style={StyleSheet.absoluteFill}
                device={device}
                // @ts-expect-error The <Camera> types are a bit tricky since they're using Unions. I'll try to flatten those out in a future PR.
                format={format}
                // @ts-expect-error The <Camera> types are a bit tricky since they're using Unions. I'll try to flatten those out in a future PR.
                fps={fps}
                // @ts-expect-error The <Camera> types are a bit tricky since they're using Unions. I'll try to flatten those out in a future PR.
                hdr={enableHdr}
                // @ts-expect-error The <Camera> types are a bit tricky since they're using Unions. I'll try to flatten those out in a future PR.
                lowLightBoost={device.supportsLowLightBoost && enableNightMode}
                isActive={isActive}
                onInitialized={onInitialized}
                onError={onError}
                enableZoomGesture={false}
                // TODO: Remove once https://github.com/software-mansion/react-native-reanimated/pull/1697 gets merged
                // @ts-expect-error animatedProps should be Partial<P>
                animatedProps={cameraAnimatedProps}
              />
            </TapGestureHandler>
          </Reanimated.View>
        </PinchGestureHandler>
      )}

      <CaptureButton
        style={styles.captureButton}
        camera={camera}
        onMediaCaptured={onMediaCaptured}
        cameraZoom={zoom}
        flash={supportsFlash ? flash : 'off'}
        enabled={isCameraInitialized && isActive}
        setIsPressingButton={setIsPressingButton}
      />

      <StatusBarBlurBackground />

      <View style={styles.rightButtonRow}>
        {supportsCameraFlipping && (
          <PressableOpacity style={styles.button} onPress={onFlipCameraPressed} disabledOpacity={0.4}>
            <IonIcon name="camera-reverse" color="white" size={24} />
          </PressableOpacity>
        )}
        {supportsFlash && (
          <PressableOpacity style={styles.button} onPress={onFlashPressed} disabledOpacity={0.4}>
            <IonIcon name={flash === 'on' ? 'flash' : 'flash-off'} color="white" size={24} />
          </PressableOpacity>
        )}
        {canToggleNightMode && (
          <PressableOpacity style={styles.button} onPress={onNightModePressed} disabledOpacity={0.4}>
            <IonIcon name={enableNightMode ? 'moon' : 'moon-outline'} color="white" size={24} />
          </PressableOpacity>
        )}
        {supportsHdr && (
          <PressableOpacity style={styles.button} onPress={onHdrSwitchPressed}>
            <MaterialIcon name={enableHdr ? 'hdr' : 'hdr-off'} color="white" size={24} />
          </PressableOpacity>
        )}
        <PressableOpacity style={styles.button} onPress={onSettingsPressed}>
          <IonIcon name="settings-outline" color="white" size={24} />
        </PressableOpacity>
      </View>
    </View>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'black',
  },
  captureButton: {
    position: 'absolute',
    alignSelf: 'center',
    bottom: SAFE_AREA_PADDING.paddingBottom,
  },
  button: {
    marginBottom: CONTENT_SPACING,
    width: BUTTON_SIZE,
    height: BUTTON_SIZE,
    borderRadius: BUTTON_SIZE / 2,
    backgroundColor: 'rgba(140, 140, 140, 0.3)',
    justifyContent: 'center',
    alignItems: 'center',
  },
  rightButtonRow: {
    position: 'absolute',
    right: SAFE_AREA_PADDING.paddingRight,
    top: SAFE_AREA_PADDING.paddingTop,
  },
});