import { TwoDimensionalPoint, TwoDimensionalBoundsType } from "../types";

type GetTwoDimensionalBoundsOptions = {
    fallbackBounds: TwoDimensionalBoundsType;
};

const DEFAULT_FALLBACK_BOUNDS: TwoDimensionalBoundsType = {
    minX: 0,
    maxX: 0,
    minY: 0,
    maxY: 0,
};

/**
 * A function that computes the bounds
 */
export function getTwoDimensionalBounds(
    points: TwoDimensionalPoint[],
    options?: GetTwoDimensionalBoundsOptions,
): TwoDimensionalBoundsType {
    // Handle the case where there are no points
    if (points.length === 0) {
        const fallbackBounds =
            options?.fallbackBounds || DEFAULT_FALLBACK_BOUNDS;
        return fallbackBounds;
    }
    // The extent of the points
    let minX = Infinity,
        minY = Infinity,
        maxX = -Infinity,
        maxY = -Infinity;

    points.forEach((p) => {
        minX = Math.min(minX, p[0]);
        minY = Math.min(minY, p[1]);
        maxX = Math.max(maxX, p[0]);
        maxY = Math.max(maxY, p[1]);
    });

    return {
        minX,
        maxX,
        minY,
        maxY,
    };
}

/**
 * computes the center of the bounds
 */
export function getCenterFromTwoDimensionalBounds({
    minX,
    maxX,
    minY,
    maxY,
}: TwoDimensionalBoundsType): TwoDimensionalPoint {
    return [minX + (maxX - minX) / 2, minY + (maxY - minY) / 2];
}

/**
 * Determines if a point is within a polygon
 * @src https://wrfranklin.org/Research/Short_Notes/pnpoly.html
 * @param {TwoDimensionalPoint} point
 * @param {TwoDimensionalPoint[]} polygon
 * @returns {boolean}
 */
export function isPointInsidePolygon(
    point: TwoDimensionalPoint,
    polygonPoints: TwoDimensionalPoint[],
) {
    const x = point[0],
        y = point[1];

    let inside = false;
    for (
        let i = 0, j = polygonPoints.length - 1;
        i < polygonPoints.length;
        j = i++
    ) {
        const xi = polygonPoints[i][0],
            yi = polygonPoints[i][1];
        const xj = polygonPoints[j][0],
            yj = polygonPoints[j][1];

        const intersect =
            yi > y != yj > y && x < ((xj - xi) * (y - yi)) / (yj - yi) + xi;
        if (intersect) inside = !inside;
    }

    return inside;
}