import {
  type CSSProperties,
  type MouseEvent,
  type PointerEvent,
  useEffect,
  useRef,
  useState,
} from 'react';
import { createPortal } from 'react-dom';

import { BRAND_ASSETS } from '../../uiAssets';
import {
  clampFloatingFeedbackPosition,
  FLOATING_FEEDBACK_DESKTOP_QUERY,
  FLOATING_FEEDBACK_DRAG_CLICK_SUPPRESS_MS,
  FLOATING_FEEDBACK_DRAG_CLICK_THRESHOLD,
  FLOATING_FEEDBACK_FORM_URL,
  FLOATING_FEEDBACK_INITIAL_LEFT,
  FLOATING_FEEDBACK_MARGIN,
  type FloatingFeedbackPosition,
  resolveFloatingFeedbackContactPanelOffset,
  resolveInitialFloatingFeedbackPosition,
} from './floatingFeedbackEntryModel';

type FloatingFeedbackDragState = {
  pointerId: number;
  source: 'mouse' | 'pointer';
  startClientX: number;
  startClientY: number;
  startLeft: number;
  startTop: number;
  hasMoved: boolean;
};

function isSameFloatingFeedbackPointer(
  currentPointerId: number,
  nextPointerId: number,
) {
  if (!Number.isFinite(currentPointerId) || !Number.isFinite(nextPointerId)) {
    return true;
  }

  return currentPointerId === nextPointerId;
}

function shouldUseMouseDragFallback() {
  return (
    typeof window !== 'undefined' &&
    typeof window.PointerEvent !== 'function'
  );
}

function getViewportSize() {
  return {
    width: window.innerWidth || document.documentElement.clientWidth,
    height: window.innerHeight || document.documentElement.clientHeight,
  };
}

function getInitialDesktopVisibility() {
  if (
    typeof window === 'undefined' ||
    typeof window.matchMedia !== 'function'
  ) {
    return false;
  }

  return window.matchMedia(FLOATING_FEEDBACK_DESKTOP_QUERY).matches;
}

export function FloatingFeedbackEntry() {
  const [isDesktopVisible, setIsDesktopVisible] = useState(
    getInitialDesktopVisibility,
  );
  const [isPointerOverEntry, setIsPointerOverEntry] = useState(false);
  const [isDragging, setIsDragging] = useState(false);
  const [position, setPosition] = useState<FloatingFeedbackPosition>(() =>
    typeof window === 'undefined'
      ? { left: FLOATING_FEEDBACK_INITIAL_LEFT, top: FLOATING_FEEDBACK_MARGIN }
      : resolveInitialFloatingFeedbackPosition(getViewportSize()),
  );
  const dragStateRef = useRef<FloatingFeedbackDragState | null>(null);
  const suppressClickUntilRef = useRef(0);

  useEffect(() => {
    if (
      typeof window === 'undefined' ||
      typeof window.matchMedia !== 'function'
    ) {
      return;
    }

    const mediaQuery = window.matchMedia(FLOATING_FEEDBACK_DESKTOP_QUERY);
    const updateVisibility = (event?: MediaQueryListEvent) => {
      setIsDesktopVisible(event?.matches ?? mediaQuery.matches);
    };

    updateVisibility();

    if (typeof mediaQuery.addEventListener === 'function') {
      mediaQuery.addEventListener('change', updateVisibility);
      return () => mediaQuery.removeEventListener('change', updateVisibility);
    }

    mediaQuery.addListener(updateVisibility);
    return () => mediaQuery.removeListener(updateVisibility);
  }, []);

  useEffect(() => {
    const clampToViewport = () => {
      setPosition((current) =>
        clampFloatingFeedbackPosition(current, getViewportSize()),
      );
    };

    window.addEventListener('resize', clampToViewport);
    return () => window.removeEventListener('resize', clampToViewport);
  }, []);

  const updateDrag = (
    pointerId: number,
    source: FloatingFeedbackDragState['source'],
    clientX: number,
    clientY: number,
  ) => {
    const dragState = dragStateRef.current;
    if (
      !dragState ||
      dragState.source !== source ||
      !isSameFloatingFeedbackPointer(dragState.pointerId, pointerId)
    ) {
      return;
    }

    const deltaX = clientX - dragState.startClientX;
    const deltaY = clientY - dragState.startClientY;
    if (
      !dragState.hasMoved &&
      Math.hypot(deltaX, deltaY) >= FLOATING_FEEDBACK_DRAG_CLICK_THRESHOLD
    ) {
      dragState.hasMoved = true;
    }

    setPosition(
      clampFloatingFeedbackPosition(
        {
          left: dragState.startLeft + deltaX,
          top: dragState.startTop + deltaY,
        },
        getViewportSize(),
      ),
    );
  };

  const stopDragById = (
    pointerId: number,
    source: FloatingFeedbackDragState['source'],
  ) => {
    const dragState = dragStateRef.current;
    if (
      !dragState ||
      dragState.source !== source ||
      !isSameFloatingFeedbackPointer(dragState.pointerId, pointerId)
    ) {
      return;
    }

    suppressClickUntilRef.current = dragState.hasMoved
      ? Date.now() + FLOATING_FEEDBACK_DRAG_CLICK_SUPPRESS_MS
      : 0;
    dragStateRef.current = null;
    setIsDragging(false);
  };

  useEffect(() => {
    const handlePointerMove = (event: globalThis.PointerEvent) => {
      const dragState = dragStateRef.current;
      if (
        !dragState ||
        !isSameFloatingFeedbackPointer(dragState.pointerId, event.pointerId)
      ) {
        return;
      }

      updateDrag(event.pointerId, 'pointer', event.clientX, event.clientY);
    };

    const stopPointerDrag = (event: globalThis.PointerEvent) => {
      stopDragById(event.pointerId, 'pointer');
    };

    window.addEventListener('pointermove', handlePointerMove);
    window.addEventListener('pointerup', stopPointerDrag);
    window.addEventListener('pointercancel', stopPointerDrag);
    return () => {
      window.removeEventListener('pointermove', handlePointerMove);
      window.removeEventListener('pointerup', stopPointerDrag);
      window.removeEventListener('pointercancel', stopPointerDrag);
    };
  }, []);

  useEffect(() => {
    const handleMouseMove = (event: globalThis.MouseEvent) => {
      const dragState = dragStateRef.current;
      if (!dragState || dragState.source !== 'mouse') {
        return;
      }

      updateDrag(Number.NaN, 'mouse', event.clientX, event.clientY);
    };

    const stopMouseDrag = () => {
      stopDragById(Number.NaN, 'mouse');
    };

    window.addEventListener('mousemove', handleMouseMove);
    window.addEventListener('mouseup', stopMouseDrag);
    return () => {
      window.removeEventListener('mousemove', handleMouseMove);
      window.removeEventListener('mouseup', stopMouseDrag);
    };
  }, []);

  const startPointerDrag = (event: PointerEvent<HTMLButtonElement>) => {
    if (event.button > 0) {
      return;
    }

    event.currentTarget.setPointerCapture?.(event.pointerId);
    setIsDragging(true);
    dragStateRef.current = {
      pointerId: event.pointerId,
      source: 'pointer',
      startClientX: event.clientX,
      startClientY: event.clientY,
      startLeft: position.left,
      startTop: position.top,
      hasMoved: false,
    };
  };

  const startMouseDrag = (event: MouseEvent<HTMLButtonElement>) => {
    if (!shouldUseMouseDragFallback() || event.button > 0) {
      return;
    }

    setIsDragging(true);
    dragStateRef.current = {
      pointerId: Number.NaN,
      source: 'mouse',
      startClientX: event.clientX,
      startClientY: event.clientY,
      startLeft: position.left,
      startTop: position.top,
      hasMoved: false,
    };
  };

  const openFeedbackForm = () => {
    if (suppressClickUntilRef.current >= Date.now()) {
      suppressClickUntilRef.current = 0;
      dragStateRef.current = null;
      return;
    }

    window.open(FLOATING_FEEDBACK_FORM_URL, '_blank', 'noopener,noreferrer');
  };

  if (!isDesktopVisible || typeof document === 'undefined') {
    return null;
  }

  const shouldShowContactPanel = isPointerOverEntry && !isDragging;
  const contactPanelOffset = resolveFloatingFeedbackContactPanelOffset(
    position,
    getViewportSize(),
  );

  return createPortal(
    <div
      className="floating-feedback-entry-shell"
      style={{
        left: `${position.left}px`,
        top: `${position.top}px`,
      }}
    >
      {shouldShowContactPanel ? (
        <div
          className="floating-feedback-entry-contact-panel"
          style={
            {
              '--floating-feedback-contact-offset': `${contactPanelOffset}px`,
            } as CSSProperties
          }
          aria-hidden="true"
        >
          <img
            src={BRAND_ASSETS.taonierFeedbackQq}
            alt=""
            draggable={false}
          />
          <img
            src={BRAND_ASSETS.taonierFeedbackWechat}
            alt=""
            draggable={false}
          />
        </div>
      ) : null}
      <button
        type="button"
        className="floating-feedback-entry"
        aria-label="反馈点我"
        onPointerEnter={() => setIsPointerOverEntry(true)}
        onPointerLeave={() => setIsPointerOverEntry(false)}
        onPointerDown={startPointerDrag}
        onMouseEnter={() => setIsPointerOverEntry(true)}
        onMouseLeave={() => setIsPointerOverEntry(false)}
        onMouseDown={startMouseDrag}
        onPointerMove={(event) =>
          updateDrag(event.pointerId, 'pointer', event.clientX, event.clientY)
        }
        onPointerUp={(event) => stopDragById(event.pointerId, 'pointer')}
        onPointerCancel={(event) => stopDragById(event.pointerId, 'pointer')}
        onClick={openFeedbackForm}
      >
        <img
          src={BRAND_ASSETS.taonierFeedbackEntry}
          alt=""
          aria-hidden="true"
          draggable={false}
        />
      </button>
    </div>,
    document.body,
  );
}