package main

import (
	"image"
	"image/color"
	"log"
	"os"

	"math"

	"github.com/disintegration/imaging"
)

type Mario struct {
	position image.Point
	dir      image.Point
	images   map[string]image.Image
	updown   string
	a        float64
	b        float64
	angle    float64
}

func loadMario(file string) image.Image {

	reader, err := os.Open(file)
	if err != nil {
		log.Fatal(err)
	}
	rawMario, _, err := image.Decode(reader)
	if err != nil {
		log.Fatal(err)
	}
	mario := imaging.Resize(rawMario, 16, 16, imaging.Lanczos)
	return mario
}

func initialMap() map[string]image.Image {
	imageMap := make(map[string]image.Image)
	imageMap["marioUp"] = loadMario("marioUp.png")
	imageMap["marioDown"] = loadMario("marioDown.png")
	return imageMap
}

// initializes the struct for the an play animation function, this could all be dumped into function that's wrapping go routine if I wanted

// this assumes mario context is up
func (a *Animation) animateMario() {
	defer a.updateMarioPosition()
	a.ctx.SetColor(color.Black)
	a.ctx.Clear()
	if a.mario.dir.X == 1 {
		a.ctx.DrawImageAnchored(a.mario.images[a.mario.updown], a.mario.position.X, a.mario.position.Y, 0.5, 0.5)
	} else {
		a.ctx.DrawImageAnchored(imaging.FlipH(a.mario.images[a.mario.updown]), a.mario.position.X, a.mario.position.Y, 0.5, 0.5)
	}
}

func (a *Animation) updateMarioPosition() {
	centerX := a.ctx.Width() / 2
	centerY := a.ctx.Height() / 2

	// Determine sprite size (use current updown image if available)
	var sprite image.Image
	if img, ok := a.mario.images[a.mario.updown]; ok && img != nil {
		sprite = img
	} else {
		for _, im := range a.mario.images {
			sprite = im
			break
		}
	}

	// default half sizes if sprite missing
	halfW, halfH := 8, 8
	if sprite != nil {
		halfW = sprite.Bounds().Dx() / 2
		halfH = sprite.Bounds().Dy() / 2
	}

	// allowable center range so the sprite stays fully on the panel
	minCenterX := halfW
	maxCenterX := a.ctx.Width() - 1 - halfW
	minCenterY := halfH
	maxCenterY := a.ctx.Height() - 1 - halfH

	// If the sprite is larger than the panel in a dimension, collapse
	// the allowed center range to the panel center so we don't get
	// immediate collisions every frame which makes Mario flash.
	if maxCenterX < minCenterX {
		minCenterX = centerX
		maxCenterX = centerX
	}
	if maxCenterY < minCenterY {
		minCenterY = centerY
		maxCenterY = centerY
	}

	// parametric angle before any reflection
	t := a.mario.angle

	// compute candidate center position on the ellipse
	marioX := int(math.Round(a.mario.a*math.Cos(t))) + centerX
	marioY := int(math.Round(a.mario.b*math.Sin(t))) + centerY

	// detect collisions against allowed center ranges
	collidedX := marioX < minCenterX || marioX > maxCenterX
	collidedY := marioY < minCenterY || marioY > maxCenterY

	// If allowed range collapsed to the center, don't reflect on that axis
	// because reflection would keep flipping every frame. Treat that as
	// non-colliding for reflection purposes (we'll clamp position later).
	if minCenterX == maxCenterX {
		collidedX = false
	}
	if minCenterY == maxCenterY {
		collidedY = false
	}

	// Reflect the parametric angle correctly:
	// - For horizontal collision we want cos(t_new) = -cos(t) => t_new = Pi - t
	// - For vertical collision we want sin(t_new) = -sin(t)   => t_new = -t
	if collidedX {
		t = math.Pi - t
	}
	if collidedY {
		t = -t
	}

	// normalize angle into [0, 2π)
	for t < 0 {
		t += 2 * math.Pi
	}
	for t >= 2*math.Pi {
		t -= 2 * math.Pi
	}
	a.mario.angle = t

	// recompute position from possibly-updated angle so sprite is inside bounds
	marioX = int(math.Round(a.mario.a*math.Cos(t))) + centerX
	marioY = int(math.Round(a.mario.b*math.Sin(t))) + centerY

	// clamp as a safety net
	if marioX < minCenterX {
		marioX = minCenterX
	}
	if marioX > maxCenterX {
		marioX = maxCenterX
	}
	if marioY < minCenterY {
		marioY = minCenterY
	}
	if marioY > maxCenterY {
		marioY = maxCenterY
	}

	a.mario.position.X = marioX
	a.mario.position.Y = marioY

	// advance angle for next frame
	a.mario.angle += 0.05
	if a.mario.angle >= 2*math.Pi {
		a.mario.angle -= 2 * math.Pi
	}

	// Direction logic (based on param t used for the current frame)
	if math.Sin(t) > 0 {
		a.mario.dir.X = -1 // moving left
	} else {
		a.mario.dir.X = 1 // moving right
	}
	if math.Cos(t) > 0 {
		a.mario.updown = "marioDown" // moving downward
	} else {
		a.mario.updown = "marioUp" // moving upward
	}
}