text: /**
   * @module ol/extent
   */
  import Corner from './extent/Corner.js';
  import Relationship from './extent/Relationship.js';
  import {assert} from './asserts.js';
  
  /**
   * An array of numbers representing an extent: `[minx, miny, maxx, maxy]`.
   * @typedef {Array<number>} Extent
   * @api
   */
  
  /**
   * Build an extent that includes all given coordinates.
   *
   * @param {Array<import("./coordinate.js").Coordinate>} coordinates Coordinates.
   * @return {Extent} Bounding extent.
   * @api
   */
  export function boundingExtent(coordinates) {
    const extent = createEmpty();
    for (let i = 0, ii = coordinates.length; i < ii; ++i) {
      extendCoordinate(extent, coordinates[i]);
    }
    return extent;
  }
  
  /**
   * @param {Array<number>} xs Xs.
   * @param {Array<number>} ys Ys.
   * @param {Extent} [opt_extent] Destination extent.
   * @private
   * @return {Extent} Extent.
   */
  function _boundingExtentXYs(xs, ys, opt_extent) {
    const minX = Math.min.apply(null, xs);
    const minY = Math.min.apply(null, ys);
    const maxX = Math.max.apply(null, xs);
    const maxY = Math.max.apply(null, ys);
    return createOrUpdate(minX, minY, maxX, maxY, opt_extent);
  }
  
  /**
   * Return extent increased by the provided value.
   * @param {Extent} extent Extent.
   * @param {number} value The amount by which the extent should be buffered.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} Extent.
   * @api
   */
  export function buffer(extent, value, opt_extent) {
    if (opt_extent) {
      opt_extent[0] = extent[0] - value;
      opt_extent[1] = extent[1] - value;
      opt_extent[2] = extent[2] + value;
      opt_extent[3] = extent[3] + value;
      return opt_extent;
    } else {
      return [
        extent[0] - value,
        extent[1] - value,
        extent[2] + value,
        extent[3] + value,
      ];
    }
  }
  
  /**
   * Creates a clone of an extent.
   *
   * @param {Extent} extent Extent to clone.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} The clone.
   */
  export function clone(extent, opt_extent) {
    if (opt_extent) {
      opt_extent[0] = extent[0];
      opt_extent[1] = extent[1];
      opt_extent[2] = extent[2];
      opt_extent[3] = extent[3];
      return opt_extent;
    } else {
      return extent.slice();
    }
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {number} x X.
   * @param {number} y Y.
   * @return {number} Closest squared distance.
   */
  export function closestSquaredDistanceXY(extent, x, y) {
    let dx, dy;
    if (x < extent[0]) {
      dx = extent[0] - x;
    } else if (extent[2] < x) {
      dx = x - extent[2];
    } else {
      dx = 0;
    }
    if (y < extent[1]) {
      dy = extent[1] - y;
    } else if (extent[3] < y) {
      dy = y - extent[3];
    } else {
      dy = 0;
    }
    return dx * dx + dy * dy;
  }
  
  /**
   * Check if the passed coordinate is contained or on the edge of the extent.
   *
   * @param {Extent} extent Extent.
   * @param {import("./coordinate.js").Coordinate} coordinate Coordinate.
   * @return {boolean} The coordinate is contained in the extent.
   * @api
   */
  export function containsCoordinate(extent, coordinate) {
    return containsXY(extent, coordinate[0], coordinate[1]);
  }
  
  /**
   * Check if one extent contains another.
   *
   * An extent is deemed contained if it lies completely within the other extent,
   * including if they share one or more edges.
   *
   * @param {Extent} extent1 Extent 1.
   * @param {Extent} extent2 Extent 2.
   * @return {boolean} The second extent is contained by or on the edge of the
   *     first.
   * @api
   */
  export function containsExtent(extent1, extent2) {
    return (
      extent1[0] <= extent2[0] &&
      extent2[2] <= extent1[2] &&
      extent1[1] <= extent2[1] &&
      extent2[3] <= extent1[3]
    );
  }
  
  /**
   * Check if the passed coordinate is contained or on the edge of the extent.
   *
   * @param {Extent} extent Extent.
   * @param {number} x X coordinate.
   * @param {number} y Y coordinate.
   * @return {boolean} The x, y values are contained in the extent.
   * @api
   */
  export function containsXY(extent, x, y) {
    return extent[0] <= x && x <= extent[2] && extent[1] <= y && y <= extent[3];
  }
  
  /**
   * Get the relationship between a coordinate and extent.
   * @param {Extent} extent The extent.
   * @param {import("./coordinate.js").Coordinate} coordinate The coordinate.
   * @return {import("./extent/Relationship.js").default} The relationship (bitwise compare with
   *     import("./extent/Relationship.js").Relationship).
   */
  export function coordinateRelationship(extent, coordinate) {
    const minX = extent[0];
    const minY = extent[1];
    const maxX = extent[2];
    const maxY = extent[3];
    const x = coordinate[0];
    const y = coordinate[1];
    let relationship = Relationship.UNKNOWN;
    if (x < minX) {
      relationship = relationship | Relationship.LEFT;
    } else if (x > maxX) {
      relationship = relationship | Relationship.RIGHT;
    }
    if (y < minY) {
      relationship = relationship | Relationship.BELOW;
    } else if (y > maxY) {
      relationship = relationship | Relationship.ABOVE;
    }
    if (relationship === Relationship.UNKNOWN) {
      relationship = Relationship.INTERSECTING;
    }
    return relationship;
  }
  
  /**
   * Create an empty extent.
   * @return {Extent} Empty extent.
   * @api
   */
  export function createEmpty() {
    return [Infinity, Infinity, -Infinity, -Infinity];
  }
  
  /**
   * Create a new extent or update the provided extent.
   * @param {number} minX Minimum X.
   * @param {number} minY Minimum Y.
   * @param {number} maxX Maximum X.
   * @param {number} maxY Maximum Y.
   * @param {Extent} [opt_extent] Destination extent.
   * @return {Extent} Extent.
   */
  export function createOrUpdate(minX, minY, maxX, maxY, opt_extent) {
    if (opt_extent) {
      opt_extent[0] = minX;
      opt_extent[1] = minY;
      opt_extent[2] = maxX;
      opt_extent[3] = maxY;
      return opt_extent;
    } else {
      return [minX, minY, maxX, maxY];
    }
  }
  
  /**
   * Create a new empty extent or make the provided one empty.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} Extent.
   */
  export function createOrUpdateEmpty(opt_extent) {
    return createOrUpdate(Infinity, Infinity, -Infinity, -Infinity, opt_extent);
  }
  
  /**
   * @param {import("./coordinate.js").Coordinate} coordinate Coordinate.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} Extent.
   */
  export function createOrUpdateFromCoordinate(coordinate, opt_extent) {
    const x = coordinate[0];
    const y = coordinate[1];
    return createOrUpdate(x, y, x, y, opt_extent);
  }
  
  /**
   * @param {Array<import("./coordinate.js").Coordinate>} coordinates Coordinates.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} Extent.
   */
  export function createOrUpdateFromCoordinates(coordinates, opt_extent) {
    const extent = createOrUpdateEmpty(opt_extent);
    return extendCoordinates(extent, coordinates);
  }
  
  /**
   * @param {Array<number>} flatCoordinates Flat coordinates.
   * @param {number} offset Offset.
   * @param {number} end End.
   * @param {number} stride Stride.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} Extent.
   */
  export function createOrUpdateFromFlatCoordinates(
    flatCoordinates,
    offset,
    end,
    stride,
    opt_extent
  ) {
    const extent = createOrUpdateEmpty(opt_extent);
    return extendFlatCoordinates(extent, flatCoordinates, offset, end, stride);
  }
  
  /**
   * @param {Array<Array<import("./coordinate.js").Coordinate>>} rings Rings.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} Extent.
   */
  export function createOrUpdateFromRings(rings, opt_extent) {
    const extent = createOrUpdateEmpty(opt_extent);
    return extendRings(extent, rings);
  }
  
  /**
   * Determine if two extents are equivalent.
   * @param {Extent} extent1 Extent 1.
   * @param {Extent} extent2 Extent 2.
   * @return {boolean} The two extents are equivalent.
   * @api
   */
  export function equals(extent1, extent2) {
    return (
      extent1[0] == extent2[0] &&
      extent1[2] == extent2[2] &&
      extent1[1] == extent2[1] &&
      extent1[3] == extent2[3]
    );
  }
  
  /**
   * Determine if two extents are approximately equivalent.
   * @param {Extent} extent1 Extent 1.
   * @param {Extent} extent2 Extent 2.
   * @param {number} tolerance Tolerance in extent coordinate units.
   * @return {boolean} The two extents differ by less than the tolerance.
   */
  export function approximatelyEquals(extent1, extent2, tolerance) {
    return (
      Math.abs(extent1[0] - extent2[0]) < tolerance &&
      Math.abs(extent1[2] - extent2[2]) < tolerance &&
      Math.abs(extent1[1] - extent2[1]) < tolerance &&
      Math.abs(extent1[3] - extent2[3]) < tolerance
    );
  }
  
  /**
   * Modify an extent to include another extent.
   * @param {Extent} extent1 The extent to be modified.
   * @param {Extent} extent2 The extent that will be included in the first.
   * @return {Extent} A reference to the first (extended) extent.
   * @api
   */
  export function extend(extent1, extent2) {
    if (extent2[0] < extent1[0]) {
      extent1[0] = extent2[0];
    }
    if (extent2[2] > extent1[2]) {
      extent1[2] = extent2[2];
    }
    if (extent2[1] < extent1[1]) {
      extent1[1] = extent2[1];
    }
    if (extent2[3] > extent1[3]) {
      extent1[3] = extent2[3];
    }
    return extent1;
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {import("./coordinate.js").Coordinate} coordinate Coordinate.
   */
  export function extendCoordinate(extent, coordinate) {
    if (coordinate[0] < extent[0]) {
      extent[0] = coordinate[0];
    }
    if (coordinate[0] > extent[2]) {
      extent[2] = coordinate[0];
    }
    if (coordinate[1] < extent[1]) {
      extent[1] = coordinate[1];
    }
    if (coordinate[1] > extent[3]) {
      extent[3] = coordinate[1];
    }
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {Array<import("./coordinate.js").Coordinate>} coordinates Coordinates.
   * @return {Extent} Extent.
   */
  export function extendCoordinates(extent, coordinates) {
    for (let i = 0, ii = coordinates.length; i < ii; ++i) {
      extendCoordinate(extent, coordinates[i]);
    }
    return extent;
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {Array<number>} flatCoordinates Flat coordinates.
   * @param {number} offset Offset.
   * @param {number} end End.
   * @param {number} stride Stride.
   * @return {Extent} Extent.
   */
  export function extendFlatCoordinates(
    extent,
    flatCoordinates,
    offset,
    end,
    stride
  ) {
    for (; offset < end; offset += stride) {
      extendXY(extent, flatCoordinates[offset], flatCoordinates[offset + 1]);
    }
    return extent;
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {Array<Array<import("./coordinate.js").Coordinate>>} rings Rings.
   * @return {Extent} Extent.
   */
  export function extendRings(extent, rings) {
    for (let i = 0, ii = rings.length; i < ii; ++i) {
      extendCoordinates(extent, rings[i]);
    }
    return extent;
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {number} x X.
   * @param {number} y Y.
   */
  export function extendXY(extent, x, y) {
    extent[0] = Math.min(extent[0], x);
    extent[1] = Math.min(extent[1], y);
    extent[2] = Math.max(extent[2], x);
    extent[3] = Math.max(extent[3], y);
  }
  
  /**
   * This function calls `callback` for each corner of the extent. If the
   * callback returns a truthy value the function returns that value
   * immediately. Otherwise the function returns `false`.
   * @param {Extent} extent Extent.
   * @param {function(import("./coordinate.js").Coordinate): S} callback Callback.
   * @return {S|boolean} Value.
   * @template S
   */
  export function forEachCorner(extent, callback) {
    let val;
    val = callback(getBottomLeft(extent));
    if (val) {
      return val;
    }
    val = callback(getBottomRight(extent));
    if (val) {
      return val;
    }
    val = callback(getTopRight(extent));
    if (val) {
      return val;
    }
    val = callback(getTopLeft(extent));
    if (val) {
      return val;
    }
    return false;
  }
  
  /**
   * Get the size of an extent.
   * @param {Extent} extent Extent.
   * @return {number} Area.
   * @api
   */
  export function getArea(extent) {
    let area = 0;
    if (!isEmpty(extent)) {
      area = getWidth(extent) * getHeight(extent);
    }
    return area;
  }
  
  /**
   * Get the bottom left coordinate of an extent.
   * @param {Extent} extent Extent.
   * @return {import("./coordinate.js").Coordinate} Bottom left coordinate.
   * @api
   */
  export function getBottomLeft(extent) {
    return [extent[0], extent[1]];
  }
  
  /**
   * Get the bottom right coordinate of an extent.
   * @param {Extent} extent Extent.
   * @return {import("./coordinate.js").Coordinate} Bottom right coordinate.
   * @api
   */
  export function getBottomRight(extent) {
    return [extent[2], extent[1]];
  }
  
  /**
   * Get the center coordinate of an extent.
   * @param {Extent} extent Extent.
   * @return {import("./coordinate.js").Coordinate} Center.
   * @api
   */
  export function getCenter(extent) {
    return [(extent[0] + extent[2]) / 2, (extent[1] + extent[3]) / 2];
  }
  
  /**
   * Get the height of an extent.
   * @param {Extent} extent Extent.
   * @return {number} Height.
   * @api
   */
  export function getHeight(extent) {
    return extent[3] - extent[1];
  }
  
  /**
   * @param {Extent} extent1 Extent 1.
   * @param {Extent} extent2 Extent 2.
   * @return {number} Intersection area.
   */
  export function getIntersectionArea(extent1, extent2) {
    const intersection = getIntersection(extent1, extent2);
    return getArea(intersection);
  }
  
  /**
   * Get the intersection of two extents.
   * @param {Extent} extent1 Extent 1.
   * @param {Extent} extent2 Extent 2.
   * @param {Extent} [opt_extent] Optional extent to populate with intersection.
   * @return {Extent} Intersecting extent.
   * @api
   */
  export function getIntersection(extent1, extent2, opt_extent) {
    const intersection = opt_extent ? opt_extent : createEmpty();
    if (intersects(extent1, extent2)) {
      if (extent1[0] > extent2[0]) {
        intersection[0] = extent1[0];
      } else {
        intersection[0] = extent2[0];
      }
      if (extent1[1] > extent2[1]) {
        intersection[1] = extent1[1];
      } else {
        intersection[1] = extent2[1];
      }
      if (extent1[2] < extent2[2]) {
        intersection[2] = extent1[2];
      } else {
        intersection[2] = extent2[2];
      }
      if (extent1[3] < extent2[3]) {
        intersection[3] = extent1[3];
      } else {
        intersection[3] = extent2[3];
      }
    } else {
      createOrUpdateEmpty(intersection);
    }
    return intersection;
  }
  
  /**
   * Get the top left coordinate of an extent.
   * @param {Extent} extent Extent.
   * @return {import("./coordinate.js").Coordinate} Top left coordinate.
   * @api
   */
  export function getTopLeft(extent) {
    return [extent[0], extent[3]];
  }
  
  /**
   * Get the top right coordinate of an extent.
   * @param {Extent} extent Extent.
   * @return {import("./coordinate.js").Coordinate} Top right coordinate.
   * @api
   */
  export function getTopRight(extent) {
    return [extent[2], extent[3]];
  }
  
  /**
   * Get the width of an extent.
   * @param {Extent} extent Extent.
   * @return {number} Width.
   * @api
   */
  export function getWidth(extent) {
    return extent[2] - extent[0];
  }
  
  /**
   * Determine if one extent intersects another.
   * @param {Extent} extent1 Extent 1.
   * @param {Extent} extent2 Extent.
   * @return {boolean} The two extents intersect.
   * @api
   */
  export function intersects(extent1, extent2) {
    return (
      extent1[0] <= extent2[2] &&
      extent1[2] >= extent2[0] &&
      extent1[1] <= extent2[3] &&
      extent1[3] >= extent2[1]
    );
  }
  
  /**
   * Determine if an extent is empty.
   * @param {Extent} extent Extent.
   * @return {boolean} Is empty.
   * @api
   */
  export function isEmpty(extent) {
    return extent[2] < extent[0] || extent[3] < extent[1];
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {Extent} [opt_extent] Extent.
   * @return {Extent} Extent.
   */
  export function returnOrUpdate(extent, opt_extent) {
    if (opt_extent) {
      opt_extent[0] = extent[0];
      opt_extent[1] = extent[1];
      opt_extent[2] = extent[2];
      opt_extent[3] = extent[3];
      return opt_extent;
    } else {
      return extent;
    }
  }
  
  /**
   * @param {Extent} extent Extent.
   * @param {number} value Value.
   */
  export function scaleFromCenter(extent, value) {
    const deltaX = ((extent[2] - extent[0]) / 2) * (value - 1);
    const deltaY = ((extent[3] - extent[1]) / 2) * (value - 1);
    extent[0] -= deltaX;
    extent[2] += deltaX;
    extent[1] -= deltaY;
    extent[3] += deltaY;
  }
  
  /**
   * Determine if the segment between two coordinates intersects (crosses,
   * touches, or is contained by) the provided extent.
   * @param {Extent} extent The extent.
   * @param {import("./coordinate.js").Coordinate} start Segment start coordinate.
   * @param {import("./coordinate.js").Coordinate} end Segment end coordinate.
   * @return {boolean} The segment intersects the extent.
   */
  export function intersectsSegment(extent, start, end) {
    let intersects = false;
    const startRel = coordinateRelationship(extent, start);
    const endRel = coordinateRelationship(extent, end);
    if (
      startRel === Relationship.INTERSECTING ||
      endRel === Relationship.INTERSECTING
    ) {
      intersects = true;
    } else {
      const minX = extent[0];
      const minY = extent[1];
      const maxX = extent[2];
      const maxY = extent[3];
      const startX = start[0];
      const startY = start[1];
      const endX = end[0];
      const endY = end[1];
      const slope = (endY - startY) / (endX - startX);
      let x, y;
      if (!!(endRel & Relationship.ABOVE) && !(startRel & Relationship.ABOVE)) {
        // potentially intersects top
        x = endX - (endY - maxY) / slope;
        intersects = x >= minX && x <= maxX;
      }
      if (
        !intersects &&
        !!(endRel & Relationship.RIGHT) &&
        !(startRel & Relationship.RIGHT)
      ) {
        // potentially intersects right
        y = endY - (endX - maxX) * slope;
        intersects = y >= minY && y <= maxY;
      }
      if (
        !intersects &&
        !!(endRel & Relationship.BELOW) &&
        !(startRel & Relationship.BELOW)
      ) {
        // potentially intersects bottom
        x = endX - (endY - minY) / slope;
        intersects = x >= minX && x <= maxX;
      }
      if (
        !intersects &&
        !!(endRel & Relationship.LEFT) &&
        !(startRel & Relationship.LEFT)
      ) {
        // potentially intersects left
        y = endY - (endX - minX) * slope;
        intersects = y >= minY && y <= maxY;
      }
    }
    return intersects;
  }
  
  /**
   * Apply a transform function to the extent.
   * @param {Extent} extent Extent.
   * @param {import("./proj.js").TransformFunction} transformFn Transform function.
   * Called with `[minX, minY, maxX, maxY]` extent coordinates.
   * @param {Extent} [opt_extent] Destination extent.
   * @param {number} [opt_stops] Number of stops per side used for the transform.
   * By default only the corners are used.
   * @return {Extent} Extent.
   * @api
   */
  export function applyTransform(extent, transformFn, opt_extent, opt_stops) {
    let coordinates = [];
    if (opt_stops > 1) {
      const width = extent[2] - extent[0];
      const height = extent[3] - extent[1];
      for (let i = 0; i < opt_stops; ++i) {
        coordinates.push(
          extent[0] + (width * i) / opt_stops,
          extent[1],
          extent[2],
          extent[1] + (height * i) / opt_stops,
          extent[2] - (width * i) / opt_stops,
          extent[3],
          extent[0],
          extent[3] - (height * i) / opt_stops
        );
      }
    } else {
      coordinates = [
        extent[0],
        extent[1],
        extent[2],
        extent[1],
        extent[2],
        extent[3],
        extent[0],
        extent[3],
      ];
    }
    transformFn(coordinates, coordinates, 2);
    const xs = [];
    const ys = [];
    for (let i = 0, l = coordinates.length; i < l; i += 2) {
      xs.push(coordinates[i]);
      ys.push(coordinates[i + 1]);
    }
    return _boundingExtentXYs(xs, ys, opt_extent);
  }
  
  /**
   * Modifies the provided extent in-place to be within the real world
   * extent.
   *
   * @param {Extent} extent Extent.
   * @param {import("./proj/Projection.js").default} projection Projection
   * @return {Extent} The extent within the real world extent.
   */
  export function wrapX(extent, projection) {
    const projectionExtent = projection.getExtent();
    const center = getCenter(extent);
    if (
      projection.canWrapX() &&
      (center[0] < projectionExtent[0] || center[0] >= projectionExtent[2])
    ) {
      const worldWidth = getWidth(projectionExtent);
      const worldsAway = Math.floor(
        (center[0] - projectionExtent[0]) / worldWidth
      );
      const offset = worldsAway * worldWidth;
      extent[0] -= offset;
      extent[2] -= offset;
    }
    return extent;
  }
  