// @flow

import React from 'react';
import type { Node } from 'react';
import ReactDOM from 'react-dom';
import warning from 'warning';
import contains from 'dom-helpers/query/contains';
import debounce from 'lodash/debounce';
import EventListener from 'react-event-listener';
import withStyles from '../styles/withStyles';
import Modal from '../internal/Modal';
import type { TransitionCallback, TransitionClasses } from '../internal/transition';
import Grow from '../transitions/Grow';
import Paper from '../Paper';

function getOffsetTop(rect, vertical) {
  let offset = 0;

  if (typeof vertical === 'number') {
    offset = vertical;
  } else if (vertical === 'center') {
    offset = rect.height / 2;
  } else if (vertical === 'bottom') {
    offset = rect.height;
  }

  return offset;
}

function getOffsetLeft(rect, horizontal) {
  let offset = 0;

  if (typeof horizontal === 'number') {
    offset = horizontal;
  } else if (horizontal === 'center') {
    offset = rect.width / 2;
  } else if (horizontal === 'right') {
    offset = rect.width;
  }

  return offset;
}

function getTransformOriginValue(transformOrigin) {
  return [transformOrigin.horizontal, transformOrigin.vertical]
    .map(n => {
      return typeof n === 'number' ? `${n}px` : n;
    })
    .join(' ');
}

// Sum the scrollTop between two elements.
function getScrollParent(parent, child) {
  let element = child;
  let scrollTop = 0;

  while (element && element !== parent) {
    element = element.parentNode;
    scrollTop += element.scrollTop;
  }
  return scrollTop;
}

export const styles = {
  paper: {
    position: 'absolute',
    overflowY: 'auto',
    overflowX: 'hidden',
    // So we see the popover when it's empty.
    // It's most likely on issue on userland.
    minWidth: 16,
    minHeight: 16,
    maxWidth: 'calc(100vw - 32px)',
    maxHeight: 'calc(100vh - 32px)',
    '&:focus': {
      outline: 'none',
    },
  },
};

export type Origin = {
  horizontal: 'left' | 'center' | 'right' | number,
  vertical: 'top' | 'center' | 'bottom' | number,
};

type ProvidedProps = {
  anchorOrigin: Origin,
  classes: Object,
  transformOrigin: Origin,
  marginThreshold: number,
};

export type Props = {
  /**
   * This is the DOM element that will be used
   * to set the position of the popover.
   */
  anchorEl?: ?HTMLElement,
  /**
   * This is the point on the anchor where the popover's
   * `anchorEl` will attach to.
   *
   * Options:
   * vertical: [top, center, bottom];
   * horizontal: [left, center, right].
   */
  anchorOrigin?: Origin,
  /**
   * The content of the component.
   */
  children: Node,
  /**
   * Useful to extend the style applied to components.
   */
  classes?: Object,
  /**
   * The elevation of the popover.
   */
  elevation?: number,
  /**
   * This function is called in order to retrieve the content anchor element.
   * It's the opposite of the `anchorEl` property.
   * The content anchor element should be an element inside the popover.
   * It's used to correctly scroll and set the position of the popover.
   * The positioning strategy tries to make the content anchor element just above the
   * anchor element.
   */
  getContentAnchorEl?: Function,
  /**
   * Specifies how close to the edge of the window the popover can appear.
   */
  marginThreshold?: number,
  /**
   * Callback fired before the component is entering.
   */
  onEnter?: TransitionCallback,
  /**
   * Callback fired when the component is entering.
   */
  onEntering?: TransitionCallback,
  /**
   * Callback fired when the component has entered.
   */
  onEntered?: TransitionCallback,
  /**
   * Callback fired before the component is exiting.
   */
  onExit?: TransitionCallback,
  /**
   * Callback fired when the component is exiting.
   */
  onExiting?: TransitionCallback,
  /**
   * Callback fired when the component has exited.
   */
  onExited?: TransitionCallback,
  /**
   * Callback fired when the component requests to be closed.
   *
   * @param {object} event The event source of the callback.
   */
  onRequestClose?: Function,
  /**
   * If `true`, the popover is visible.
   */
  open: boolean,
  /**
   * Properties applied to the `Paper` element.
   */
  PaperProps?: Object,
  /**
   * @ignore
   */
  role?: string,
  /**
   * This is the point on the popover which
   * will attach to the anchor's origin.
   *
   * Options:
   * vertical: [top, center, bottom, x(px)];
   * horizontal: [left, center, right, x(px)].
   */
  transformOrigin?: Origin,
  /**
   * The animation classNames applied to the component as it enters or exits.
   * This property is a direct binding to [`CSSTransition.classNames`](https://reactcommunity.org/react-transition-group/#CSSTransition-prop-classNames).
   */
  transitionClasses?: TransitionClasses,
  /**
   * Set to 'auto' to automatically calculate transition time based on height.
   */
  transitionDuration?: number | { enter?: number, exit?: number } | 'auto',
};

class Popover extends React.Component<ProvidedProps & Props> {
  static defaultProps = {
    anchorOrigin: {
      vertical: 'top',
      horizontal: 'left',
    },
    transformOrigin: {
      vertical: 'top',
      horizontal: 'left',
    },
    transitionDuration: 'auto',
    elevation: 8,
    marginThreshold: 16,
  };

  componentWillUnmount = () => {
    this.handleResize.cancel();
  };

  setPositioningStyles = (element: HTMLElement) => {
    if (element && element.style) {
      const positioning = this.getPositioningStyle(element);

      element.style.top = positioning.top;
      element.style.left = positioning.left;
      element.style.transformOrigin = positioning.transformOrigin;
    }
  };

  getPositioningStyle = element => {
    const { marginThreshold } = this.props;

    // Check if the parent has requested anchoring on an inner content node
    const contentAnchorOffset = this.getContentAnchorOffset(element);
    // Get the offset of of the anchoring element
    const anchorOffset = this.getAnchorOffset(contentAnchorOffset);

    const elemRect = {
      width: element.clientWidth,
      height: element.clientHeight,
    };
    // Get the transform origin point on the element itself
    const transformOrigin = this.getTransformOrigin(elemRect, contentAnchorOffset);

    // Calculate element positioning
    let top = anchorOffset.top - transformOrigin.vertical;
    let left = anchorOffset.left - transformOrigin.horizontal;
    const bottom = top + elemRect.height;
    const right = left + elemRect.width;

    // Window thresholds taking required margin into account
    const heightThreshold = window.innerHeight - marginThreshold;
    const widthThreshold = window.innerWidth - marginThreshold;

    // Check if the vertical axis needs shifting
    if (top < marginThreshold) {
      const diff = top - marginThreshold;
      top -= diff;
      transformOrigin.vertical += diff;
    } else if (bottom > heightThreshold) {
      const diff = bottom - heightThreshold;
      top -= diff;
      transformOrigin.vertical += diff;
    }

    warning(
      elemRect.height < heightThreshold || !elemRect.height || !heightThreshold,
      [
        'Material-UI: the popover component is too tall.',
        `Some part of it can not be seen on the screen (${elemRect.height - heightThreshold}px).`,
        'Please consider adding a `max-height` to improve the user-experience.',
      ].join('\n'),
    );

    // Check if the horizontal axis needs shifting
    if (left < marginThreshold) {
      const diff = left - marginThreshold;
      left -= diff;
      transformOrigin.horizontal += diff;
    } else if (right > widthThreshold) {
      const diff = right - widthThreshold;
      left -= diff;
      transformOrigin.horizontal += diff;
    }

    return {
      top: `${top}px`,
      left: `${left}px`,
      transformOrigin: getTransformOriginValue(transformOrigin),
    };
  };

  // Returns the top/left offset of the position
  // to attach to on the anchor element (or body if none is provided)
  getAnchorOffset(contentAnchorOffset) {
    // $FlowFixMe
    const { anchorEl, anchorOrigin } = this.props;
    const anchorElement = anchorEl || document.body;
    const anchorRect = anchorElement.getBoundingClientRect();
    const anchorVertical = contentAnchorOffset === 0 ? anchorOrigin.vertical : 'center';

    return {
      top: anchorRect.top + this.handleGetOffsetTop(anchorRect, anchorVertical),
      left: anchorRect.left + this.handleGetOffsetLeft(anchorRect, anchorOrigin.horizontal),
    };
  }

  // Returns the vertical offset of inner content to anchor the transform on if provided
  getContentAnchorOffset(element) {
    let contentAnchorOffset = 0;

    if (this.props.getContentAnchorEl) {
      const contentAnchorEl = this.props.getContentAnchorEl(element);

      if (contentAnchorEl && contains(element, contentAnchorEl)) {
        const scrollTop = getScrollParent(element, contentAnchorEl);
        contentAnchorOffset =
          contentAnchorEl.offsetTop + contentAnchorEl.clientHeight / 2 - scrollTop || 0;
      }

      // != the default value
      warning(
        this.props.anchorOrigin.vertical === 'top',
        [
          'Material-UI: you can not change the default `anchorOrigin.vertical` value when also ',
          'providing the `getContentAnchorEl` property to the popover component.',
          'Only use one of the two properties',
          'Set `getContentAnchorEl` to null or left `anchorOrigin.vertical` unchanged',
        ].join(),
      );
    }

    return contentAnchorOffset;
  }

  // Return the base transform origin using the element
  // and taking the content anchor offset into account if in use
  getTransformOrigin(elemRect, contentAnchorOffset = 0) {
    const { transformOrigin } = this.props;
    return {
      vertical: this.handleGetOffsetTop(elemRect, transformOrigin.vertical) + contentAnchorOffset,
      horizontal: this.handleGetOffsetLeft(elemRect, transformOrigin.horizontal),
    };
  }

  transitionEl = undefined;

  handleGetOffsetTop = getOffsetTop;

  handleGetOffsetLeft = getOffsetLeft;

  handleEnter = (element: HTMLElement) => {
    if (this.props.onEnter) {
      this.props.onEnter(element);
    }

    this.setPositioningStyles(element);
  };

  handleResize = debounce(() => {
    const element: any = ReactDOM.findDOMNode(this.transitionEl);
    this.setPositioningStyles(element);
  }, 166);

  render() {
    const {
      anchorEl,
      anchorOrigin,
      children,
      classes,
      elevation,
      getContentAnchorEl,
      marginThreshold,
      onEnter,
      onEntering,
      onEntered,
      onExit,
      onExiting,
      onExited,
      open,
      PaperProps,
      role,
      transformOrigin,
      transitionClasses,
      transitionDuration,
      ...other
    } = this.props;

    return (
      <Modal show={open} BackdropInvisible {...other}>
        <Grow
          appear
          in={open}
          onEnter={this.handleEnter}
          onEntering={onEntering}
          onEntered={onEntered}
          onExit={onExit}
          onExiting={onExiting}
          onExited={onExited}
          role={role}
          transitionClasses={transitionClasses}
          timeout={transitionDuration}
          rootRef={node => {
            this.transitionEl = node;
          }}
        >
          <Paper
            data-mui-test="Popover"
            className={classes.paper}
            elevation={elevation}
            {...PaperProps}
          >
            <EventListener target="window" onResize={this.handleResize} />
            {children}
          </Paper>
        </Grow>
      </Modal>
    );
  }
}

export default withStyles(styles, { name: 'MuiPopover' })(Popover);