utils.ts

namespace Utils {
    export function getArrayOfLength(length: number): number[] {
        const result = []
        for (let i = 0; i < length; i++) {
            result.push(i)
        }
        return result
    }

    // Used to re-use an animation but flip it horizontally (x)
    export function flipAnimation(frames: Image[]) {
        return frames.map((frame: Image) => {
            frame.flipX()
            return frame
        })
    }

    export function getDistance(pointA: { x: number, y: number }, pointB: { x: number, y: number }) {
        const dx = pointB.x - pointA.x;
        const dy = pointB.y - pointA.y;

        return Math.abs(Math.sqrt(dx * dx + dy * dy));
    }

    export function swapAnimationColors(anim: Image[], fromColor: number, toColor: number) {
        anim.map(frame => frame.replace(fromColor, toColor))
        return anim
    }

    export function getHitEnemies({ pirate, enemies }: { pirate: Pirate, enemies: Enemy[] }) {
        const dirPix = pirate.direction === 'left' ? -1 : 1
        // The hit zone is the pirate "sword" box: [center, right|left] and [top, bottom]
        const hitXZone = [pirate.sprite.x, pirate.sprite.x + (13 * dirPix)]
        // The sword is only near the top of the sprite, we don't kill with feet
        const hitYZone = [pirate.sprite.y - 4, pirate.sprite.y + 2]

        // manually check each enemy to see if they overlap, also check for parry
        return enemies.reduce((hitEnemies, enemy) => {
            // Don't hurt the dead, that's just mean
            if (enemy.health <= 0 && enemy.riches <= 0) {
                return hitEnemies
            }

            if (pirate.direction === 'right'
                && enemy.sprite.x >= hitXZone[0] && enemy.sprite.x <= hitXZone[1]
                // Bottom of pirate is overlapping the top of the enemy (and opposite)
                && hitYZone[1] >= enemy.sprite.y - (enemy.sprite.height / 2) && hitYZone[0] <= enemy.sprite.y + (enemy.sprite.height / 2)) {
                    hitEnemies.push(enemy)
            } else if (pirate.direction === 'left'
                && enemy.sprite.x <= hitXZone[0] && enemy.sprite.x >= hitXZone[1]
                // Same vertical check as the right side
                && hitYZone[1] >= enemy.sprite.y - (enemy.sprite.height / 2) && hitYZone[0] <= enemy.sprite.y + (enemy.sprite.height / 2)) {
                    hitEnemies.push(enemy)
            }

            return hitEnemies
        }, [])
    }
}