package sprite

import (
	"fmt"

	rl "github.com/gen2brain/raylib-go/raylib"
)

// spriteAnimation specifies which subsections of a spritesheet define this animation.
// For example, walking to the right could be defined by 4 subsections of a sprite sheet.
type spriteAnimation struct {
	spritesheet *spritesheet
	dimensions  rl.Vector2
	offset      rl.Vector2
	length      int
	border      int
}

func NewAnimation(
	filename string,
	dimensions rl.Vector2,
	offset rl.Vector2,
	length int,
	border int,
) spriteAnimation {

	spritesheet := GetSpritesheet(filename)

	return spriteAnimation{
		spritesheet: spritesheet,
		dimensions:  dimensions,
		offset:      offset,
		length:      length,
		border:      border,
	}
}

func (a spriteAnimation) Draw(
	frame int,
	windowPosition rl.Vector2,
	angle float32,
	center rl.Vector2,
	flip rl.Vector2,
	color rl.Color,
) error {

	width := a.dimensions.X
	height := a.dimensions.Y
	border := float32(a.border)

	base := rl.Vector2{
		X: (width+border)*a.offset.X + border,
		Y: (height+border)*a.offset.Y + border,
	}

	// Assuming all frames are horizontal going left to right.
	// Potentially with a border offset as well.
	f := float32(frame % a.length)
	section := rl.Rectangle{
		X:      base.X + f*(width+border),
		Y:      base.Y,
		Width:  width,
		Height: height,
	}

	if flip.X > 0 {
		section.Width *= -1
	}
	if flip.Y > 0 {
		section.Height *= -1
	}

	err := a.checkBounds(section)
	if err != nil {
		return err
	}

	placement := rl.Rectangle{
		X:      windowPosition.X,
		Y:      windowPosition.Y,
		Width:  width * 2,
		Height: height * 2,
	}

	err = a.spritesheet.Draw(section, placement, angle, center, color)
	if err != nil {
		return err
	}

	return nil
}

func (a spriteAnimation) checkBounds(section rl.Rectangle) error {
	width := float32(a.spritesheet.texture.Width)
	height := float32(a.spritesheet.texture.Height)

	outOfBounds := false
	if section.X < 0 {
		outOfBounds = true
	}
	if section.Y < 0 {
		outOfBounds = true
	}
	if section.X+section.Width > width {
		outOfBounds = true
	}
	if section.Y+section.Height > height {
		outOfBounds = true
	}

	if outOfBounds {
		return fmt.Errorf("draw section was out of bounds - section: %v, image: %v", section, a.spritesheet.Bounds())
	}

	return nil
}