package coffee.liz.ecs

import kotlin.math.sqrt

/**
 * Rectangle in cartesian space.
 */
data class Rect(
    val topLeft: Vec2,
    val dimensions: Vec2,
) {
    fun contains(point: Vec2): Boolean =
        point.x >= topLeft.x &&
            point.x <= topLeft.x + dimensions.x &&
            point.y >= topLeft.y &&
            point.y <= topLeft.y + dimensions.y

    fun overlaps(other: Rect): Boolean {
        val xOverlap =
            topLeft.x <= other.topLeft.x + other.dimensions.x &&
                topLeft.x + dimensions.x >= other.topLeft.x
        val yOverlap =
            topLeft.y <= other.topLeft.y + other.dimensions.y &&
                topLeft.y + dimensions.y >= other.topLeft.y
        return xOverlap && yOverlap
    }

    fun split(newDimensions: Vec2): List<List<Rect>> = List(
        (dimensions.y / newDimensions.y).toInt()
    ) { y ->
        List(
            (dimensions.x / newDimensions.x).toInt()
        ) { x ->
            Rect(
                topLeft = topLeft.plus(Vec2(x * newDimensions.x, y * newDimensions.y)),
                dimensions = newDimensions,
            )
        }
    }
}

/**
 * Cartesian point.
 */
data class Vec2(
    val x: Float,
    val y: Float,
) {
    fun plus(other: Vec2): Vec2 = Vec2(x + other.x, y + other.y)

    fun minus(other: Vec2): Vec2 = Vec2(x - other.x, y - other.y)

    fun scale(x: Float, y: Float): Vec2 = Vec2(this.x * x, this.y * y)

    fun distanceTo(other: Vec2): Float = (this.minus(other)).length()

    fun normalize(): Vec2 = this.scale(1 / length(), 1 / length())

    fun length(): Float = sqrt(x * x + y * y)
}

/**
 * Cardinal directions.
 */
enum class CardinalDirection(
    val direction: Vec2,
) {
    NORTH(Vec2(0f, -1f)),
    SOUTH(Vec2(0f, 1f)),
    WEST(Vec2(-1f, 0f)),
    EAST(Vec2(1f, 0f)),
}