package color

import (
	"errors"
	"fmt"
	"strconv"
	"strings"
)

type Space struct {
	ChromaSampling       ChromaSampling
	ChromaSamplePosition ChromaSamplePosition
	BitDepth             byte
}

func (c Space) String() string {
	if c.ChromaSampling.J == 4 && c.ChromaSampling.A == 2 && c.ChromaSampling.B == 0 && c.BitDepth == 8 {
		switch c.ChromaSamplePosition {
		case ChromaSamplePositionCenter:
			return "420jpeg"
		case ChromaSamplePositionTopLeft:
			return "420paldv"
		case ChromaSamplePositionLeft:
			return "420mpeg2"
		}
	}
	if c.ChromaSampling.J == 4 && c.ChromaSampling.A == 0 && c.ChromaSampling.B == 0 {
		return fmt.Sprintf("mono%d", c.BitDepth)
	}

	return fmt.Sprintf("%d%d%dp%d", c.ChromaSampling.J, c.ChromaSampling.A, c.ChromaSampling.B, c.BitDepth)
}

func (c Space) FrameSizePacked(width, height int) (int, error) {
	a1 := int64(width) * int64(height)
	a2 := int64(c.ChromaSampling.ElementPixels())
	if a1%a2 != 0 {
		return 0, errors.New("not divisible pixels")
	}
	a3 := (a1 / a2) * int64(c.ChromaSampling.ElementSamples()) * int64(c.BitDepth)
	if a3%8 != 0 {
		return 0, errors.New("not divisible size")
	}

	return int(a3 / 8), nil
}

func (c Space) FrameSize(width, height int) (int, error) {
	actualBitDepth := int64(c.BitDepth)
	if actualBitDepth&0b111 != 0 {
		actualBitDepth = ((actualBitDepth + 8) >> 3) << 3
	}

	a1 := int64(width) * int64(height)
	a2 := int64(c.ChromaSampling.ElementPixels())
	if a1%a2 != 0 {
		return 0, errors.New("not divisible pixels")
	}
	a3 := (a1 / a2) * int64(c.ChromaSampling.ElementSamples()) * actualBitDepth
	if a3%8 != 0 {
		return 0, errors.New("not divisible size")
	}

	return int(a3 / 8), nil
}

func (c Space) check() error {
	if c.ChromaSampling.J <= 0 {
		return fmt.Errorf("unsupported J %d", c.ChromaSampling.J)
	}
	if c.ChromaSampling.A < 0 && c.ChromaSampling.A > c.ChromaSampling.J {
		return fmt.Errorf("unsupported A %d", c.ChromaSampling.A)
	}
	if c.ChromaSampling.B != 0 && c.ChromaSampling.B != c.ChromaSampling.A {
		return fmt.Errorf("unsupported B %d", c.ChromaSampling.B)
	}
	if c.BitDepth != 8 && c.BitDepth != 10 && c.BitDepth != 12 && c.BitDepth != 14 && c.BitDepth != 16 {
		return fmt.Errorf("unsupported BitDepth %d", c.BitDepth)
	}

	return nil
}

func NewColorFormatFromString(colorFormat string) (Space, error) {
	colorFormat = strings.ToLower(colorFormat)
	if colorFormat == "420paldv" {
		c, err := NewColorFormatFromString("420p8")
		c.ChromaSamplePosition = ChromaSamplePositionTopLeft
		return c, err
	} else if colorFormat == "420mpeg2" {
		c, err := NewColorFormatFromString("420p8")
		c.ChromaSamplePosition = ChromaSamplePositionLeft
		return c, err
	} else if colorFormat == "420" || colorFormat == "420jpeg" || colorFormat == "420j" {
		c, err := NewColorFormatFromString("420p8")
		c.ChromaSamplePosition = ChromaSamplePositionCenter
		return c, err
	} else if colorFormat == "mono" {
		return NewColorFormatFromString("400p8")
	} else if colorFormat == "mono10" {
		return NewColorFormatFromString("400p10")
	} else if colorFormat == "mono12" {
		return NewColorFormatFromString("400p12")
	} else if colorFormat == "mono14" {
		return NewColorFormatFromString("400p14")
	} else if colorFormat == "mono16" {
		return NewColorFormatFromString("400p16")
	}

	splits := strings.Split(colorFormat, "p")
	if len(splits) == 1 { //default 8 bit
		splits = append(splits, "8")
	}

	space := Space{
		ChromaSamplePosition: ChromaSamplePositionUnspecified,
	}
	switch strings.ReplaceAll(splits[0], ":", "") {
	case "400":
		space.ChromaSampling.J = 4
		space.ChromaSampling.A = 0
		space.ChromaSampling.B = 0
	case "420":
		space.ChromaSampling.J = 4
		space.ChromaSampling.A = 2
		space.ChromaSampling.B = 0
	case "422":
		space.ChromaSampling.J = 4
		space.ChromaSampling.A = 2
		space.ChromaSampling.B = 2
	case "444":
		space.ChromaSampling.J = 4
		space.ChromaSampling.A = 4
		space.ChromaSampling.B = 4
	default:
		return space, fmt.Errorf("unsupported Chroma ChromaSampling %s", splits[0])
	}

	n, err := strconv.Atoi(splits[1])
	if err != nil {
		return space, err
	}
	space.BitDepth = byte(n)

	return space, space.check()
}

func newColorFormatFromStringInternal(colorFormat string) Space {
	space, _ := NewColorFormatFromString(colorFormat)
	return space
}

var (
	Space420    Space = newColorFormatFromStringInternal("420")
	Space422    Space = newColorFormatFromStringInternal("422")
	Space444    Space = newColorFormatFromStringInternal("444")
	Space420P10 Space = newColorFormatFromStringInternal("420p10")
	Space422P10 Space = newColorFormatFromStringInternal("422p10")
	Space444P10 Space = newColorFormatFromStringInternal("444p10")
	Space420P12 Space = newColorFormatFromStringInternal("420p12")
	Space422P12 Space = newColorFormatFromStringInternal("422p12")
	Space444P12 Space = newColorFormatFromStringInternal("444p12")
	Space420P16 Space = newColorFormatFromStringInternal("420p16")
	Space422P16 Space = newColorFormatFromStringInternal("422p16")
	Space444P16 Space = newColorFormatFromStringInternal("444p16")
)