package elements

import (
	"fluids/fluid"
	"fluids/gamedata"
	"fluids/resources"
	"image/color"

	"github.com/hajimehoshi/ebiten/v2"
)

const (
	RoundedBottomFlaskWidth           = 32  //pixels
	RoundedBottomFlaskHeight          = 32  //pixels
	RoundedBottomFlaskFluidRadius     = 9   //pixels: represents spherical portion of the flask where fluid will be contained
	RoundedBottomFlaskFluidOriginX    = 16  //pixels: x origin of fluid area
	RoundedBottomFlaskFluidOriginY    = 20  //pixels: y origin of fluid area
	RoundedBottomFlaskFluidWidth      = 0.5 //meters
	RoundedBottomFlaskFluidHeight     = 0.5 //meters
	RoundedBottomFlaskFluidResolution = 20
)

type RoundedBottomFlask struct {
	MappedEntityBase
	fluid          *fluid.Fluid    //our physical representation of the fluid
	fluidbuff      *ebiten.Image   //predraw for the fluid
	fluidcellbuff  *ebiten.Image   //persistent fluid sprite, we redraw this everywhere we want to represent fluid
	flaskbase      *ebiten.Image   //flask background (container)
	flaskhighlight *ebiten.Image   //flask foreground (glassware highlights)
	fieldscale     gamedata.Vector //used for transforming from fluid-space to sprite-space
	angle          float64

	//fluid color business
	fluidcolor  color.RGBA //premultiplied fluid color, as set by external sources
	fluidcolorF []float32  //for caching of individual color values, we compute rarely
}

func NewRoundedBottomFlask() *RoundedBottomFlask {
	flask := &RoundedBottomFlask{
		fluidbuff:      ebiten.NewImage(RoundedBottomFlaskFluidRadius*2, RoundedBottomFlaskFluidRadius*2),
		fluidcellbuff:  ebiten.NewImage(1, 1),
		flaskbase:      ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskBase]),
		flaskhighlight: ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskHighlights]),
		angle:          0,
		fluidcolorF:    make([]float32, 4), //one field each for R,G,B,A
	}
	flask.Initialize()
	return flask
}

func (flask *RoundedBottomFlask) Initialize() {
	//prepare our internal data
	flask.dimensions = gamedata.Vector{
		X: RoundedBottomFlaskWidth,
		Y: RoundedBottomFlaskHeight,
	}
	flask.Sprite = ebiten.NewImage(RoundedBottomFlaskWidth, RoundedBottomFlaskHeight)
	flask.fluidcellbuff.Fill(color.White)

	//prepare and initialize the fluid
	fluiddimensions := fluid.FieldVector{
		X: RoundedBottomFlaskFluidWidth,
		Y: RoundedBottomFlaskFluidHeight,
	}
	flask.fluid = fluid.NewFluid(fluiddimensions, RoundedBottomFlaskFluidHeight/RoundedBottomFlaskFluidResolution)
	flask.fluid.Initialize()
	flask.fluid.Block = false //rounded flask, not a rect volume

	//compute fieldscale using newly created fluid
	flask.fieldscale = gamedata.Vector{
		X: RoundedBottomFlaskFluidRadius * 2 / float64(flask.fluid.Field.Nx-1),
		Y: RoundedBottomFlaskFluidRadius * 2 / float64(flask.fluid.Field.Ny-1),
	}

	//setup default fluid color
	flask.SetFluidColor(color.RGBA{R: 0x0, G: 0x0, B: 0xff, A: 0xff})
}

func (flask *RoundedBottomFlask) Update() {
	if flask.paused {
		return
	}

	flask.fluid.Step()
}

func (flask *RoundedBottomFlask) Draw() {
	flask.Sprite.Clear()

	//render flask background
	flask.Sprite.DrawImage(flask.flaskbase, nil)

	//render fluid
	flask.RenderFluid()

	//render flask foreground
	flask.Sprite.DrawImage(flask.flaskhighlight, nil)

}

func (flask *RoundedBottomFlask) SetAngle(angle float64) {
	flask.angle = angle
	flask.fluid.SetAngle(float32(flask.angle))
}

func (flask *RoundedBottomFlask) GetAngle() float64 {
	return flask.angle
}

func (flask *RoundedBottomFlask) RenderFluid() {
	flask.fluidbuff.Clear()

	//construct fluid buffer from fluid simulation
	for i := range flask.fluid.Field.Nx {
		for j := range flask.fluid.Field.Ny {

			idx := i*flask.fluid.Field.Ny + j

			if flask.fluid.Field.CellType[idx] != fluid.CellTypeFluid {
				continue
			}

			celldensity := flask.fluid.ParticleDensity[idx] / flask.fluid.ParticleRestDensity
			/*if celldensity > 0.8 {
				celldensity = 1
			}*/

			ox := float64(i) * flask.fieldscale.X
			oy := float64(j) * flask.fieldscale.Y
			op := &ebiten.DrawImageOptions{}
			op.GeoM.Translate(-.5, -.5)
			op.GeoM.Scale(flask.fieldscale.X, flask.fieldscale.Y)
			op.GeoM.Translate(ox, oy)
			op.ColorScale.ScaleAlpha(celldensity)
			op.ColorScale.Scale(flask.fluidcolorF[0], flask.fluidcolorF[1], flask.fluidcolorF[2], flask.fluidcolorF[3])
			//			op.ColorM.Scale(0, 0, 1, 1)
			//flask.Sprite.DrawImage(flask.fluidcellbuff, op)
			flask.fluidbuff.DrawImage(flask.fluidcellbuff, op)
		}
	}

	//transform buffer for our flask space
	op := &ebiten.DrawImageOptions{}

	op.GeoM.Translate(-RoundedBottomFlaskFluidRadius, -RoundedBottomFlaskFluidRadius)
	op.GeoM.Scale(1, -1)
	op.GeoM.Translate(RoundedBottomFlaskFluidOriginX, RoundedBottomFlaskFluidOriginY)
	flask.Sprite.DrawImage(flask.fluidbuff, op)
}

func (flask *RoundedBottomFlask) SetFluidColor(c color.RGBA) {
	flask.fluidcolor = c
	flask.fluidcolorF[0] = float32(flask.fluidcolor.R) / float32(flask.fluidcolor.A)
	flask.fluidcolorF[1] = float32(flask.fluidcolor.G) / float32(flask.fluidcolor.A)
	flask.fluidcolorF[2] = float32(flask.fluidcolor.B) / float32(flask.fluidcolor.A)
	flask.fluidcolorF[3] = float32(flask.fluidcolor.A) / 0xff
}