import mitt from 'mitt';
import { InjectionKey, Ref } from 'vue';

export type LayoutItem = {
  i: string | number
  x: number
  y: number
  h: number
  w: number
  minW?: number
  minH?: number
  maxW?: number
  maxH?: number
  static?: boolean
  moved?: boolean
  isDraggable?: boolean
  isResizable?: boolean
};
export type Layout = Array<LayoutItem>;
// export type ResizeEvent = {e: Event, node: HTMLElement, size: Size};
/* eslint-disable @typescript-eslint/no-use-before-define */
// const isProduction = process.env.NODE_ENV === 'production';
/**
 * 返回布局的 Bottom 坐标
 *
 * @param  {Array} layout Layout array.
 * @return {Number}       Bottom 坐标.
 */
export function bottom(layout: Layout): number {
  let max = 0;
  let bottomY = 0;
  for (let i = 0, len = layout.length; i < len; i++) {
    bottomY = layout[i].y + layout[i].h;
    if (bottomY > max) max = bottomY;
  }
  return max;
}

// Fast path to cloning, since this is monomorphic
export function cloneLayoutItem(layoutItem: LayoutItem): LayoutItem {
  /* return {
    w: layoutItem.w, h: layoutItem.h, x: layoutItem.x, y: layoutItem.y, i: layoutItem.i,
    minW: layoutItem.minW, maxW: layoutItem.maxW, minH: layoutItem.minH, maxH: layoutItem.maxH,
    moved: Boolean(layoutItem.moved), static: Boolean(layoutItem.static),
    // These can be null
    isDraggable: layoutItem.isDraggable, isResizable: layoutItem.isResizable
  };*/
  return JSON.parse(JSON.stringify(layoutItem));
}

/**
 * 克隆一个新的布局
 * @param layout
 * @returns newLayout
 */
export function cloneLayout(layout: Layout): Layout {
  const newLayout = Array(layout.length);
  for (let i = 0, len = layout.length; i < len; i++) {
    newLayout[i] = cloneLayoutItem(layout[i]);
  }
  return newLayout;
}

/**
 * Given two layoutitems, check if they collide.
 *
 * @return {Boolean}   True if colliding.
 */
export function collides(l1: LayoutItem, l2: LayoutItem): boolean {
  if (l1 === l2) return false; // same element
  if (l1.x + l1.w <= l2.x) return false; // l1 is left of l2
  if (l1.x >= l2.x + l2.w) return false; // l1 is right of l2
  if (l1.y + l1.h <= l2.y) return false; // l1 is above l2
  if (l1.y >= l2.y + l2.h) return false; // l1 is below l2
  return true; // boxes overlap
}

/**
 * 紧凑布局，消除Y轴的间隙
 *
 * @param  {Array} layout Layout.
 * @param  {Boolean} verticalCompact 是否紧凑布局
 * @return {Array}       Compacted Layout.
 */
export function compact(layout: Layout, verticalCompact: boolean): Layout {
  // Statics go in the compareWith array right away so items flow around them.
  const compareWith = getStatics(layout);
  // We go through the items by row and column.
  const sorted = sortLayoutItemsByRowCol(layout);
  // Holding for new items.
  const out = Array(layout.length);

  for (let i = 0, len = sorted.length; i < len; i++) {
    let l = sorted[i];

    // Don't move static elements
    if (!l.static) {
      l = compactItem(compareWith, l, verticalCompact);

      // Add to comparison array. We only collide with items before this one.
      // Statics are already in this array.
      compareWith.push(l);
    }

    // Add to output array to make sure they still come out in the right order.
    out[layout.indexOf(l)] = l;

    // Clear moved flag, if it exists.
    l.moved = false;
  }

  return out;
}

/**
 * Compact an item in the layout.
 */
export function compactItem(compareWith: Layout, l: LayoutItem, verticalCompact: boolean): LayoutItem {
  if (verticalCompact) {
    // Move the element up as far as it can go without colliding.
    while (l.y > 0 && !getFirstCollision(compareWith, l)) {
      // eslint-disable-next-line no-plusplus
      l.y--;
    }
  }

  // Move it down, and keep moving it down if it's colliding.
  // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
  let collides = {} as LayoutItem | void;
  while ((collides = getFirstCollision(compareWith, l))) {
    l.y = collides.y + collides.h;
  }
  return l;
}

/**
 * Given a layout, make sure all elements fit within its bounds.
 *
 * @param  {Array} layout Layout array.
 * @param  {Number} bounds Number of columns.
 */
export function correctBounds(layout: Layout, bounds: { cols: number }): Layout {
  const collidesWith = getStatics(layout);
  for (let i = 0, len = layout.length; i < len; i++) {
    const l = layout[i];
    // Overflows right
    if (l.x + l.w > bounds.cols) l.x = bounds.cols - l.w;
    // Overflows left
    if (l.x < 0) {
      l.x = 0;
      l.w = bounds.cols;
    }
    if (!l.static) collidesWith.push(l);
    else {
      // If this is static and collides with other statics, we must move it down.
      // We have to do something nicer than just letting them overlap.
      while (getFirstCollision(collidesWith, l)) {
        // eslint-disable-next-line no-plusplus
        l.y++;
      }
    }
  }
  return layout;
}

/**
 * Get a layout item by ID. Used so we can override later on if necessary.
 *
 * @param  {Array}  layout Layout array.
 * @param  {String} id     ID
 * @return {LayoutItem}    Item at ID.
 */
export function getLayoutItem(layout: Layout, id: string | number): LayoutItem | undefined {
  for (let i = 0, len = layout.length; i < len; i++) {
    if (layout[i].i === id) return layout[i];
  }
}

/**
 * Returns the first item this layout collides with.
 * It doesn't appear to matter which order we approach this from, although
 * perhaps that is the wrong thing to do.
 *
 * @param  {Object} layoutItem Layout item.
 * @return {Object|undefined}  A colliding layout item, or undefined.
 */
export function getFirstCollision(layout: Layout, layoutItem: LayoutItem): LayoutItem | void {
  for (let i = 0, len = layout.length; i < len; i++) {
    if (collides(layout[i], layoutItem)) return layout[i];
  }
}

export function getAllCollisions(layout: Layout, layoutItem: LayoutItem): Layout {
  return layout.filter(l => collides(l, layoutItem));
}

/**
 * Get all static elements.
 * @param  {Array} layout Array of layout objects.
 * @return {Array}        Array of static layout items..
 */
export function getStatics(layout: Layout): Layout {
  // return [];
  return layout.filter(l => l.static);
}

/**
 * Move an element. Responsible for doing cascading movements of other elements.
 *
 * @param  {Array}      layout Full layout to modify.
 * @param  {LayoutItem} l      element to move.
 * @param  {Number}     [x]    X position in grid units.
 * @param  {Number}     [y]    Y position in grid units.
 * @param  {Boolean}    [isUserAction] If true, designates that the item we're moving is
 *                                     being dragged/resized by th euser.
 */
export function moveElement(
  layout: Layout,
  l: LayoutItem,
  x: number | void,
  y: number,
  isUserAction: boolean,
  preventCollision = false,
) {
  if (l.static) return layout;

  // Short-circuit if nothing to do.
  // if (l.y === y && l.x === x) return layout;

  const oldX = l.x;
  const oldY = l.y;

  const movingUp = y && l.y > y;
  // This is quite a bit faster than extending the object
  if (typeof x === 'number') l.x = x;
  if (typeof y === 'number') l.y = y;
  l.moved = true;

  // If this collides with anything, move it.
  // When doing this comparison, we have to sort the items we compare with
  // to ensure, in the case of multiple collisions, that we're getting the
  // nearest collision.
  let sorted = sortLayoutItemsByRowCol(layout);
  if (movingUp) sorted = sorted.reverse();
  const collisions = getAllCollisions(sorted, l);

  if (preventCollision && collisions.length) {
    l.x = oldX;
    l.y = oldY;
    l.moved = false;
    return layout;
  }

  // Move each item that collides away from this element.
  for (let i = 0, len = collisions.length; i < len; i++) {
    const collision = collisions[i];
    // console.log('resolving collision between', l.i, 'at', l.y, 'and', collision.i, 'at', collision.y);

    // Short circuit so we can't infinite loop
    if (collision.moved) continue;

    // This makes it feel a bit more precise by waiting to swap for just a bit when moving up.
    if (l.y > collision.y && l.y - collision.y > collision.h / 4) continue;

    // Don't move static items - we have to move *this* element away
    if (collision.static) {
      layout = moveElementAwayFromCollision(layout, collision, l, isUserAction);
    } else {
      layout = moveElementAwayFromCollision(layout, l, collision, isUserAction);
    }
  }

  return layout;
}

/**
 * This is where the magic needs to happen - given a collision, move an element away from the collision.
 * We attempt to move it up if there's room, otherwise it goes below.
 *
 * @param  {Array} layout            Full layout to modify.
 * @param  {LayoutItem} collidesWith Layout item we're colliding with.
 * @param  {LayoutItem} itemToMove   Layout item we're moving.
 * @param  {Boolean} [isUserAction]  If true, designates that the item we're moving is being dragged/resized
 *                                   by the user.
 */
export function moveElementAwayFromCollision(
  layout: Layout,
  collidesWith: LayoutItem,
  itemToMove: LayoutItem,
  isUserAction: boolean,
) {
  const preventCollision = false; // we're already colliding
  // If there is enough space above the collision to put this element, move it there.
  // We only do this on the main collision as this can get funky in cascades and cause
  // unwanted swapping behavior.
  if (isUserAction) {
    // Make a mock item so we don't modify the item here, only modify in moveElement.
    const fakeItem: LayoutItem = {
      x: itemToMove.x,
      y: itemToMove.y,
      w: itemToMove.w,
      h: itemToMove.h,
      i: '-1',
    };
    fakeItem.y = Math.max(collidesWith.y - itemToMove.h, 0);
    if (!getFirstCollision(layout, fakeItem)) {
      return moveElement(layout, itemToMove, undefined, fakeItem.y, preventCollision);
    }
  }

  // Previously this was optimized to move below the collision directly, but this can cause problems
  // with cascading moves, as an item may actually leapflog a collision and cause a reversal in order.
  return moveElement(layout, itemToMove, undefined, itemToMove.y + 1, preventCollision);
}

export function setTransform(top: number, left: number, width: number, height: number) {
  // Replace unitless items with px
  const translate = `translate3d(${left}px,${top < 0 ? 0 : top}px, 0)`;
  return {
    transform: translate,
    WebkitTransform: translate,
    MozTransform: translate,
    msTransform: translate,
    OTransform: translate,
    width: `${width}px`,
    height: `${height}px`,
    position: 'absolute',
  };
}

/**
 * Just like the setTransform method, but instead it will return a negative value of right.
 *
 * @param top
 * @param right
 * @param width
 * @param height
 * @returns {{transform: string, WebkitTransform: string, MozTransform: string,
 * msTransform: string, OTransform: string, width: string, height: string, position: string}}
 */
export function setTransformRtl(top: number, right: number, width: number, height: number) {
  // Replace unitless items with px
  const translate = `translate3d(${right * -1}px,${top < 0 ? 0 : top}px, 0)`;
  return {
    transform: translate,
    WebkitTransform: translate,
    MozTransform: translate,
    msTransform: translate,
    OTransform: translate,
    width: `${width}px`,
    height: `${height}px`,
    position: 'absolute',
  };
}

export function setTopLeft(top: number, left: number, width: number, height: number) {
  return {
    top: `${top}px`,
    left: `${left}px`,
    width: `${width}px`,
    height: `${height}px`,
    position: 'absolute',
  };
}

/**
 * Just like the setTopLeft method, but instead, it will return a right property instead of left.
 *
 * @param top
 * @param right
 * @param width
 * @param height
 * @returns {{top: string, right: string, width: string, height: string, position: string}}
 */
export function setTopRight(top: number, right: number, width: number, height: number) {
  return {
    top: `${top}px`,
    right: `${right}px`,
    width: `${width}px`,
    height: `${height}px`,
    position: 'absolute',
  };
}

/**
 * Get layout items sorted from top left to right and down.
 *
 * @return {Array} Array of layout objects.
 * @return {Array} Layout, sorted static items first.
 */
export function sortLayoutItemsByRowCol(layout: Layout): Layout {
  return [...layout].sort((a, b) => {
    if (a.y === b.y && a.x === b.x) {
      return 0;
    }

    if (a.y > b.y || (a.y === b.y && a.x > b.x)) {
      return 1;
    }

    return -1;
  });
}

/**
 * Validate a layout. Throws errors.
 *
 * @param  {Array}  layout        Array of layout items.
 * @param  {String} [contextName] Context name for errors.
 * @throw  {Error}                Validation error.
 */
export function validateLayout(layout: Layout, contextName = 'Layout'): void {
  const subProps = ['x', 'y', 'w', 'h'];
  if (!Array.isArray(layout)) throw new Error(`${contextName} must be an array!`);
  for (let i = 0, len = layout.length; i < len; i++) {
    const item = layout[i];
    // eslint-disable-next-line @typescript-eslint/prefer-for-of
    for (let j = 0; j < subProps.length; j++) {
      if (typeof item[subProps[j] as keyof LayoutItem] !== 'number') {
        throw new Error(`VueGridLayout: ${contextName}[${i}].${subProps[j]} must be a number!`);
      }
    }
    if (item.i && typeof item.i !== 'string') {
      // number is also ok, so comment the error
      // TODO confirm if commenting the line below doesn't cause unexpected problems
      // throw new Error('VueGridLayout: ' + contextName + '[' + i + '].i must be a string!');
    }
    if (item.static !== undefined && typeof item.static !== 'boolean') {
      throw new Error(`VueGridLayout: ${contextName}[${i}].static must be a boolean!`);
    }
  }
}

const eventBus = mitt();
type eventBusType = typeof eventBus;
export const eventBusKey: InjectionKey<eventBusType> = Symbol('eventBus');
export const parentRootKey: InjectionKey<any> = Symbol('parentRoot');
export const isDraggableKey: InjectionKey<Ref<boolean>> = Symbol('isDraggable');
export const isResizableKey: InjectionKey<Ref<boolean>> = Symbol('isResizable');
export const rowHeightKey: InjectionKey<Ref<number>> = Symbol('rowHeight');
export const maxRowsKey: InjectionKey<Ref<number>> = Symbol('maxRows');
export const colNumKey: InjectionKey<Ref<number>> = Symbol('colNum');
export const containerWidthKey: InjectionKey<Ref<number>> = Symbol('containerWidth');
export const marginKey: InjectionKey<Ref<number[]>> = Symbol('margin');
export const useCssTransformsKey: InjectionKey<Ref<boolean>> = Symbol('useCssTransforms');
export const isMirroredKey: InjectionKey<Ref<boolean>> = Symbol('isMirrored');