package client

import (
	"io/fs"
	"os"
	"path/filepath"

	"github.com/chompy/roguelike_rpg/internal/util"
	"github.com/hajimehoshi/ebiten/v2"
	lua "github.com/rosbit/luago"
)

type VisualEffect struct {
	Loop   bool
	Time   float32
	Shader *ebiten.Shader
	luaCtx *lua.LuaContext
}

func LoadVisualEffect(assetFS fs.FS, name string) (*VisualEffect, error) {
	effect := &VisualEffect{}
	luaScript, err := util.ReadString(assetFS, filepath.Join("visual_effects", name+".lua"))
	if err != nil && !os.IsNotExist(err) {
		return nil, err
	}
	if err == nil {
		ctx, err := lua.NewContext()
		if err != nil {
			return nil, err
		}
		if err := ctx.LoadScript(luaScript, map[string]any{}); err != nil {
			return nil, err
		}
		res, err := ctx.CallFunc("Loop")
		if err != nil {
			return nil, err
		}
		loop, ok := res.(bool)
		if !ok {
			loop = false
		}
		effect.Loop = loop
		effect.luaCtx = ctx
	}

	shaderBytes, err := util.ReadBytes(assetFS, filepath.Join("visual_effects", name+".kage"))
	if err != nil && !os.IsNotExist(err) {
		return nil, err
	}
	if err == nil {
		shader, err := ebiten.NewShader(shaderBytes)
		if err != nil {
			return nil, err
		}
		effect.Shader = shader
	}

	return effect, nil
}

func (v *VisualEffect) Apply(time float32, op *ebiten.DrawImageOptions) (bool, error) {
	if v.luaCtx != nil {
		res, err := v.luaCtx.CallFunc("Apply", time, map[string]any{
			"GeoM":       &op.GeoM,
			"ColorScale": &op.ColorScale,
		})
		if err != nil {
			return false, err
		}
		playing, ok := res.(bool)
		if ok {
			return playing, nil
		}
	}
	return false, nil
}