// https://en.wikipedia.org/wiki/HSL_and_HSV
import {ColorHSB, ColorRGB} from './common'

export function rgbToHsb(color: ColorRGB) {
    const {r, g, b} = color

    if ([r, g, b].some(v => v < 0 || v > 255)) {
        throw new TypeError('r, g, b ∈ [0, 255]')
    }

    const max = Math.max(r, g, b)
    const min = Math.min(r, g, b)

    let h = 0
    if (max === min) {
        h = 0
    } else if (max === r) {
        h = 60 * ((g - b) / (max - min))
    } else if (max === g) {
        h = 60 * ((b - r) / (max - min)) + 120
    }
    // else if (max === b) {
    else {
        h = 60 * ((r - g) / (max - min)) + 240
    }

    return {
        h: h < 0 ? h + 360 : h,
        s: max === 0 ? 0 : ((max - min) / max) * 100,
        b: (max / 255) * 100,
    }
}

export function hsbToRgb(color: ColorHSB) {
    const {h, s, b} = color

    if (h < 0 || h > 360) {
        throw new TypeError('hue: s ∈ [0°, 360°]')
    }
    if (s < 0 || s > 100) {
        throw new TypeError('saturation: s ∈ [0, 100]')
    }
    if (b < 0 || b > 100) {
        throw new TypeError('brightness: b ∈ [0, 100]')
    }

    const c = (b / 100) * (s / 100)
    const x = c * (1 - Math.abs((h / 60) % 2 - 1))
    const m = b / 100 - c

    let rRGB = 0
    let gRGB = 0
    let bRGB = 0

    if (0 <= h && h <= 60) {
        rRGB = c
        gRGB = x
        bRGB = 0
    } else if (60 < h && h <= 120) {
        rRGB = x
        gRGB = c
        bRGB = 0
    } else if (120 < h && h <= 180) {
        rRGB = 0
        gRGB = c
        bRGB = x
    } else if (180 < h && h <= 240) {
        rRGB = 0
        gRGB = x
        bRGB = c
    } else if (240 < h && h <= 300) {
        rRGB = x
        gRGB = 0
        bRGB = c
    // } else if (300 < h && h <= 360) {
    } else {
        rRGB = c
        gRGB = 0
        bRGB = x
    }

    return {
        r: Math.round((rRGB + m) * 255),
        g: Math.round((gRGB + m) * 255),
        b: Math.round((bRGB + m) * 255),
    }

}