package color

import (
	"encoding/json"
	"fmt"
	"github.com/lucasb-eyer/go-colorful"
	"math"
	"strconv"
	"strings"
)

type Color struct {
	RGB *RGB    `json:"rgb,omitempty"`
	HS  *HueSat `json:"hs,omitempty"`
	K   *int    `json:"k,omitempty"`
	XY  *XY     `json:"xy,omitempty"`
}

func (col *Color) MarshalJSON() ([]byte, error) {
	return json.Marshal(col.String())
}

func (col *Color) UnmarshalJSON(bytes []byte) error {
	var s string
	err := json.Unmarshal(bytes, &s)
	if err != nil {
		return err
	}

	*col, err = Parse(s)
	return err
}

func (col *Color) IsHueSat() bool {
	return col.HS != nil
}

func (col *Color) IsHueSatKelvin() bool {
	return col.HS != nil && col.K != nil
}

func (col *Color) IsKelvin() bool {
	return col.K != nil
}

func (col *Color) IsEmpty() bool {
	return *col == Color{}
}

func (col *Color) SetK(k int) {
	*col = Color{K: &k}
}

func (col *Color) SetXY(xy XY) {
	*col = Color{XY: &xy}
}

func (col *Color) AlmostEquals(other Color) bool {
	if (col.K != nil) != (other.K != nil) {
		return false
	}

	if col.HS != nil && other.HS != nil {
		if math.Abs(col.HS.Hue-other.HS.Hue) > 0.01 {
			return false
		}
		if math.Abs(col.HS.Sat-other.HS.Sat) > 0.01 {
			return false
		}

		if col.K != nil && *col.K != *other.K {
			return false
		}

		return true
	}

	if col.K != nil {
		return *col.K == *other.K
	}

	if col.RGB != nil && other.RGB != nil {
		if math.Abs(col.RGB.Red-other.RGB.Red) > 0.01 {
			return false
		}
		if math.Abs(col.RGB.Blue-other.RGB.Blue) > 0.01 {
			return false
		}
		if math.Abs(col.RGB.Green-other.RGB.Green) > 0.01 {
			return false
		}

		return true
	}

	xy1, _ := col.ToXY()
	xy2, _ := col.ToXY()
	if math.Abs(xy1.XY.X-xy2.XY.X) > 0.001 {
		return false
	}
	if math.Abs(xy1.XY.Y-xy2.XY.Y) > 0.001 {
		return false
	}

	return true
}

// ToRGB tries to copy the color to an RGB color. If it's already RGB, it will be plainly copied, but HS
// will be returned. If ok is false, then no copying has occurred and cv2 will be blank.
func (col *Color) ToRGB() (col2 Color, ok bool) {
	if col.RGB != nil {
		rgb := *col.RGB
		col2 = Color{RGB: &rgb}
		ok = true
	} else if col.HS != nil {
		rgb := col.HS.ToRGB()
		col2 = Color{RGB: &rgb}
		ok = true
	} else if col.XY != nil {
		rgb := col.XY.ToRGB()
		col2 = Color{RGB: &rgb}
		ok = true
	} else if col.K != nil {
		rgb := kToRGB(*col.K)
		col2 = Color{RGB: &rgb}
		ok = true
	}

	return
}

func (col *Color) ToHS() (col2 Color, ok bool) {
	if col.HS != nil {
		hs := *col.HS
		col2 = Color{HS: &hs}
		ok = true
	} else if col.RGB != nil {
		hs := col.RGB.ToHS()
		col2 = Color{HS: &hs}
		ok = true
	} else if col.XY != nil {
		hs := col.XY.ToHS()
		col2 = Color{HS: &hs}
		ok = true
	} else if col.K != nil {
		hs := kToRGB(*col.K).ToHS()
		col2 = Color{HS: &hs}
		ok = true
	}

	return
}

func (col *Color) ToHSK() (col2 Color, ok bool) {
	k := 4000

	if col.HS != nil {
		hs := *col.HS
		col2 = Color{HS: &hs}

		if col.K != nil {
			k = *col.K
		}
		col2.K = &k

		ok = true
	} else if col.RGB != nil {
		hs := col.RGB.ToHS()
		col2 = Color{HS: &hs}
		col2.K = &k
		ok = true
	} else if col.XY != nil {
		hs := col.XY.ToHS()
		col2 = Color{HS: &hs}
		col2.K = &k
		ok = true
	} else if col.K != nil {
		k = *col.K
		col2.HS = &HueSat{Hue: 0, Sat: 0}
		col2.K = &k
		ok = true
	}

	return
}

// ToXY tries to copy the color to an XY color.
func (col *Color) ToXY() (col2 Color, ok bool) {
	if col.XY != nil {
		xy := *col.XY
		col2 = Color{XY: &xy}
		ok = true
	} else if col.HS != nil {
		xy := col.HS.ToXY()
		col2 = Color{XY: &xy}
		ok = true
	} else if col.RGB != nil {
		xy := col.RGB.ToXY()
		col2 = Color{XY: &xy}
		ok = true
	} else if col.K != nil {
		xy := kToRGB(*col.K).ToXY()
		col2 = Color{XY: &xy}
		ok = true
	}

	return
}

func (col *Color) Interpolate(other Color, fac float64) Color {
	if col.AlmostEquals(other) {
		return *col
	}

	// Special case for kelvin values.
	if col.IsKelvin() && other.IsKelvin() {
		k1 := *col.K
		k2 := *col.K
		k3 := k1 + int(float64(k2-k1)*fac)
		return Color{K: &k3}
	}

	if fac < 0.000001 {
		return *col
	} else if fac > 0.999999 {
		return other
	}

	// Get the colorful values.
	cvCF := col.colorful()
	otherCF := other.colorful()

	// Blend and normalize (clamping is hax to avoid issues with some colors)
	blended := cvCF.BlendLuv(otherCF, fac)
	blendedHue, blendedSat, _ := blended.Hsv()
	blendedHs := HueSat{Hue: blendedHue, Sat: blendedSat}

	// Convert to the first's type
	switch col.Kind() {
	case "rgb":
		rgb := blendedHs.ToRGB()
		return Color{RGB: &rgb}
	case "xy":
		xy := blendedHs.ToXY()
		return Color{XY: &xy}
	default:
		return Color{HS: &blendedHs}
	}
}

func (col *Color) Kind() string {
	switch {
	case col.RGB != nil:
		return "rgb"
	case col.XY != nil:
		return "xy"
	case col.HS != nil && col.K != nil:
		return "hsk"
	case col.HS != nil:
		return "hs"
	case col.K != nil:
		return "k"
	default:
		return ""
	}
}

func (col *Color) String() string {
	switch {
	case col.RGB != nil:
		return fmt.Sprintf("rgb:%.3f,%.3f,%.3f", col.RGB.Red, col.RGB.Green, col.RGB.Blue)
	case col.XY != nil:
		return fmt.Sprintf("xy:%.4f,%.4f", col.XY.X, col.XY.Y)
	case col.HS != nil && col.K != nil:
		return fmt.Sprintf("hsk:%.4f,%.3f,%d", col.HS.Hue, col.HS.Sat, *col.K)
	case col.HS != nil:
		return fmt.Sprintf("hs:%.4f,%.3f", col.HS.Hue, col.HS.Sat)
	case col.K != nil:
		return fmt.Sprintf("k:%d", *col.K)
	default:
		return ""
	}
}

func (col *Color) colorful() colorful.Color {
	switch {
	case col.HS != nil:
		return colorful.Hsv(col.HS.Hue, col.HS.Sat, 1)
	case col.RGB != nil:
		return colorful.Color{R: col.RGB.Red, G: col.RGB.Green, B: col.RGB.Blue}
	case col.XY != nil:
		return colorful.Xyy(col.XY.X, col.XY.Y, 0.5)
	default:
		return colorful.Color{R: 1, B: 1, G: 1}
	}
}

func MustParse(raw string) Color {
	col, err := Parse(raw)
	if err != nil {
		panic(err)
	}

	return col
}

func Parse(raw string) (col Color, err error) {
	if raw == "" {
		return
	}

	tokens := strings.SplitN(raw, ":", 2)
	if len(tokens) != 2 {
		err = ErrBadColorInput
		return
	}

	switch tokens[0] {
	case "kelvin", "k":
		{
			parsedPart, err := strconv.Atoi(tokens[1])
			if err != nil {
				err = ErrBadColorInput
				break
			}

			col.K = &parsedPart
		}

	case "xy":
		{
			parts := strings.Split(tokens[1], ",")
			if len(parts) < 2 {
				err = ErrUnknownColorFormat
				return
			}

			x, err1 := strconv.ParseFloat(parts[0], 64)
			y, err2 := strconv.ParseFloat(parts[1], 64)
			if err1 != nil || err2 != nil {
				err = ErrBadColorInput
				break
			}

			col.XY = &XY{x, y}
		}

	case "hs":
		{
			parts := strings.Split(tokens[1], ",")
			if len(parts) < 2 {
				err = ErrUnknownColorFormat
				return
			}

			part1, err1 := strconv.ParseFloat(parts[0], 64)
			part2, err2 := strconv.ParseFloat(parts[1], 64)
			if err1 != nil || err2 != nil {
				err = ErrBadColorInput
				break
			}

			col.HS = &HueSat{Hue: part1, Sat: part2}
		}

	case "hsk":
		{
			parts := strings.Split(tokens[1], ",")
			if len(parts) < 3 {
				err = ErrUnknownColorFormat
				return
			}

			part1, err1 := strconv.ParseFloat(parts[0], 64)
			part2, err2 := strconv.ParseFloat(parts[1], 64)
			part3, err3 := strconv.Atoi(parts[2])
			if err1 != nil || err2 != nil || err3 != nil {
				err = ErrBadColorInput
				break
			}

			col.HS = &HueSat{Hue: part1, Sat: part2}
			col.K = &part3
		}

	case "rgb":
		{
			if strings.HasPrefix(tokens[1], "#") {
				hex := tokens[1][1:]
				if !validHex(hex) {
					err = ErrBadColorInput
					break
				}

				if len(hex) == 6 {
					col.RGB = &RGB{
						Red:   float64(hex2num(hex[0:2])) / 255.0,
						Green: float64(hex2num(hex[2:4])) / 255.0,
						Blue:  float64(hex2num(hex[4:6])) / 255.0,
					}
				} else if len(hex) == 3 {
					col.RGB = &RGB{
						Red:   float64(hex2digit(hex[0])) / 15.0,
						Green: float64(hex2digit(hex[1])) / 15.0,
						Blue:  float64(hex2digit(hex[2])) / 15.0,
					}
				} else {
					err = ErrUnknownColorFormat
					return
				}
			} else {
				parts := strings.Split(tokens[1], ",")
				if len(parts) < 3 {
					err = ErrUnknownColorFormat
					return
				}

				part1, err1 := strconv.ParseFloat(parts[0], 64)
				part2, err2 := strconv.ParseFloat(parts[1], 64)
				part3, err3 := strconv.ParseFloat(parts[2], 64)
				if err1 != nil || err2 != nil || err3 != nil {
					err = ErrBadColorInput
					break
				}

				col.RGB = &RGB{Red: part1, Green: part2, Blue: part3}
			}

			normalizedRGB := col.RGB.ToHS().ToRGB()
			col.RGB = &normalizedRGB
		}

	default:
		err = ErrUnknownColorFormat
	}

	return
}

func validHex(h string) bool {
	for _, ch := range h {
		if !((ch >= 'a' && ch <= 'f') || (ch >= '0' || ch <= '9')) {
			return false
		}
	}

	return true
}

func hex2num(s string) int {
	v := 0
	for _, h := range s {
		v *= 16
		v += hex2digit(byte(h))
	}

	return v
}

func hex2digit(h byte) int {
	if h >= 'a' && h <= 'f' {
		return 10 + int(h-'a')
	} else {
		return int(h - '0')
	}
}

func kToRGB(kelvin int) RGB {
	if kelvin < 1000 {
		kelvin = 1000
	} else if kelvin > 12000 {
		kelvin = 12000
	}
	if kelvin%100 == 0 {
		return kelvinRGBTable[kelvin]
	}

	fac := float64(kelvin%100) / 100
	floor := (kelvin / 100) * 100
	ceil := floor + 100
	floorRGB := kelvinRGBTable[floor]
	ceilRGB := kelvinRGBTable[ceil]

	return RGB{
		Red:   (floorRGB.Red * fac) + (ceilRGB.Red * (1 - fac)),
		Green: (floorRGB.Green * fac) + (ceilRGB.Green * (1 - fac)),
		Blue:  (floorRGB.Blue * fac) + (ceilRGB.Blue * (1 - fac)),
	}
}

var kelvinRGBTable = map[int]RGB{
	1000:  {Red: 1.000, Green: 0.220, Blue: 0.000},
	1100:  {Red: 1.000, Green: 0.278, Blue: 0.000},
	1200:  {Red: 1.000, Green: 0.325, Blue: 0.000},
	1300:  {Red: 1.000, Green: 0.365, Blue: 0.000},
	1400:  {Red: 1.000, Green: 0.396, Blue: 0.000},
	1500:  {Red: 1.000, Green: 0.427, Blue: 0.000},
	1600:  {Red: 1.000, Green: 0.451, Blue: 0.000},
	1700:  {Red: 1.000, Green: 0.475, Blue: 0.000},
	1800:  {Red: 1.000, Green: 0.494, Blue: 0.000},
	1900:  {Red: 1.000, Green: 0.514, Blue: 0.000},
	2000:  {Red: 1.000, Green: 0.541, Blue: 0.071},
	2100:  {Red: 1.000, Green: 0.557, Blue: 0.129},
	2200:  {Red: 1.000, Green: 0.576, Blue: 0.173},
	2300:  {Red: 1.000, Green: 0.596, Blue: 0.212},
	2400:  {Red: 1.000, Green: 0.616, Blue: 0.247},
	2500:  {Red: 1.000, Green: 0.631, Blue: 0.282},
	2600:  {Red: 1.000, Green: 0.647, Blue: 0.310},
	2700:  {Red: 1.000, Green: 0.663, Blue: 0.341},
	2800:  {Red: 1.000, Green: 0.678, Blue: 0.369},
	2900:  {Red: 1.000, Green: 0.694, Blue: 0.396},
	3000:  {Red: 1.000, Green: 0.706, Blue: 0.420},
	3100:  {Red: 1.000, Green: 0.722, Blue: 0.447},
	3200:  {Red: 1.000, Green: 0.733, Blue: 0.471},
	3300:  {Red: 1.000, Green: 0.745, Blue: 0.494},
	3400:  {Red: 1.000, Green: 0.757, Blue: 0.518},
	3500:  {Red: 1.000, Green: 0.769, Blue: 0.537},
	3600:  {Red: 1.000, Green: 0.780, Blue: 0.561},
	3700:  {Red: 1.000, Green: 0.788, Blue: 0.580},
	3800:  {Red: 1.000, Green: 0.800, Blue: 0.600},
	3900:  {Red: 1.000, Green: 0.808, Blue: 0.624},
	4000:  {Red: 1.000, Green: 0.820, Blue: 0.639},
	4100:  {Red: 1.000, Green: 0.827, Blue: 0.659},
	4200:  {Red: 1.000, Green: 0.835, Blue: 0.678},
	4300:  {Red: 1.000, Green: 0.843, Blue: 0.694},
	4400:  {Red: 1.000, Green: 0.851, Blue: 0.714},
	4500:  {Red: 1.000, Green: 0.859, Blue: 0.729},
	4600:  {Red: 1.000, Green: 0.867, Blue: 0.745},
	4700:  {Red: 1.000, Green: 0.875, Blue: 0.761},
	4800:  {Red: 1.000, Green: 0.882, Blue: 0.776},
	4900:  {Red: 1.000, Green: 0.890, Blue: 0.792},
	5000:  {Red: 1.000, Green: 0.894, Blue: 0.808},
	5100:  {Red: 1.000, Green: 0.902, Blue: 0.824},
	5200:  {Red: 1.000, Green: 0.910, Blue: 0.835},
	5300:  {Red: 1.000, Green: 0.914, Blue: 0.851},
	5400:  {Red: 1.000, Green: 0.922, Blue: 0.863},
	5500:  {Red: 1.000, Green: 0.925, Blue: 0.878},
	5600:  {Red: 1.000, Green: 0.933, Blue: 0.890},
	5700:  {Red: 1.000, Green: 0.937, Blue: 0.902},
	5800:  {Red: 1.000, Green: 0.941, Blue: 0.914},
	5900:  {Red: 1.000, Green: 0.949, Blue: 0.925},
	6000:  {Red: 1.000, Green: 0.953, Blue: 0.937},
	6100:  {Red: 1.000, Green: 0.957, Blue: 0.949},
	6200:  {Red: 1.000, Green: 0.961, Blue: 0.961},
	6300:  {Red: 1.000, Green: 0.965, Blue: 0.969},
	6400:  {Red: 1.000, Green: 0.973, Blue: 0.984},
	6500:  {Red: 1.000, Green: 0.976, Blue: 0.992},
	6600:  {Red: 0.996, Green: 0.976, Blue: 1.000},
	6700:  {Red: 0.988, Green: 0.969, Blue: 1.000},
	6800:  {Red: 0.976, Green: 0.965, Blue: 1.000},
	6900:  {Red: 0.969, Green: 0.961, Blue: 1.000},
	7000:  {Red: 0.961, Green: 0.953, Blue: 1.000},
	7100:  {Red: 0.953, Green: 0.949, Blue: 1.000},
	7200:  {Red: 0.941, Green: 0.945, Blue: 1.000},
	7300:  {Red: 0.937, Green: 0.941, Blue: 1.000},
	7400:  {Red: 0.929, Green: 0.937, Blue: 1.000},
	7500:  {Red: 0.922, Green: 0.933, Blue: 1.000},
	7600:  {Red: 0.914, Green: 0.929, Blue: 1.000},
	7700:  {Red: 0.906, Green: 0.925, Blue: 1.000},
	7800:  {Red: 0.902, Green: 0.922, Blue: 1.000},
	7900:  {Red: 0.894, Green: 0.918, Blue: 1.000},
	8000:  {Red: 0.890, Green: 0.914, Blue: 1.000},
	8100:  {Red: 0.882, Green: 0.910, Blue: 1.000},
	8200:  {Red: 0.878, Green: 0.906, Blue: 1.000},
	8300:  {Red: 0.871, Green: 0.902, Blue: 1.000},
	8400:  {Red: 0.867, Green: 0.902, Blue: 1.000},
	8500:  {Red: 0.863, Green: 0.898, Blue: 1.000},
	8600:  {Red: 0.855, Green: 0.898, Blue: 1.000},
	8700:  {Red: 0.851, Green: 0.890, Blue: 1.000},
	8800:  {Red: 0.847, Green: 0.890, Blue: 1.000},
	8900:  {Red: 0.843, Green: 0.886, Blue: 1.000},
	9000:  {Red: 0.839, Green: 0.882, Blue: 1.000},
	9100:  {Red: 0.831, Green: 0.882, Blue: 1.000},
	9200:  {Red: 0.827, Green: 0.878, Blue: 1.000},
	9300:  {Red: 0.824, Green: 0.875, Blue: 1.000},
	9400:  {Red: 0.820, Green: 0.875, Blue: 1.000},
	9500:  {Red: 0.816, Green: 0.871, Blue: 1.000},
	9600:  {Red: 0.812, Green: 0.867, Blue: 1.000},
	9700:  {Red: 0.812, Green: 0.867, Blue: 1.000},
	9800:  {Red: 0.808, Green: 0.863, Blue: 1.000},
	9900:  {Red: 0.804, Green: 0.863, Blue: 1.000},
	10000: {Red: 0.812, Green: 0.855, Blue: 1.000},
	10100: {Red: 0.812, Green: 0.855, Blue: 1.000},
	10200: {Red: 0.808, Green: 0.851, Blue: 1.000},
	10300: {Red: 0.804, Green: 0.851, Blue: 1.000},
	10400: {Red: 0.800, Green: 0.847, Blue: 1.000},
	10500: {Red: 0.800, Green: 0.847, Blue: 1.000},
	10600: {Red: 0.796, Green: 0.843, Blue: 1.000},
	10700: {Red: 0.792, Green: 0.843, Blue: 1.000},
	10800: {Red: 0.792, Green: 0.839, Blue: 1.000},
	10900: {Red: 0.788, Green: 0.839, Blue: 1.000},
	11000: {Red: 0.784, Green: 0.835, Blue: 1.000},
	11100: {Red: 0.784, Green: 0.835, Blue: 1.000},
	11200: {Red: 0.780, Green: 0.831, Blue: 1.000},
	11300: {Red: 0.776, Green: 0.831, Blue: 1.000},
	11400: {Red: 0.776, Green: 0.831, Blue: 1.000},
	11500: {Red: 0.773, Green: 0.827, Blue: 1.000},
	11600: {Red: 0.773, Green: 0.827, Blue: 1.000},
	11700: {Red: 0.773, Green: 0.824, Blue: 1.000},
	11800: {Red: 0.769, Green: 0.824, Blue: 1.000},
	11900: {Red: 0.765, Green: 0.824, Blue: 1.000},
	12000: {Red: 0.765, Green: 0.820, Blue: 1.000},
}