package game

import (
	"image"
	"log"
	"openquell/assets"
	"openquell/components"
	"openquell/grid"
	"openquell/observers"
	"openquell/systems"
	"strings"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/mlange-42/arche/ecs"
)

type Level struct {
	Cellsize, Width, Height int
	World                   *ecs.World
	Name                    string
	Description             string
	Mapslice                map[image.Point]*assets.Tile

	Player     *systems.PlayerSystem
	GridSystem *systems.GridSystem

	Grid *grid.Grid
}

func NewLevel(game *Game, cellsize int, plan *assets.RawLevel) *Level {
	gridsystem := systems.NewGridSystem(game.World, game.ScreenWidth,
		game.ScreenHeight, cellsize, plan.Background)
	playersystem := systems.NewPlayerSystem(game.World, gridsystem)

	return &Level{
		Mapslice:    LevelToSlice(game, plan, cellsize),
		Cellsize:    cellsize,
		World:       game.World,
		Width:       game.ScreenWidth,
		Height:      game.ScreenHeight,
		Description: plan.Description,
		Name:        plan.Name,
		GridSystem:  gridsystem,
		Player:      playersystem,
	}
}

func (level *Level) Update() {
	level.GridSystem.Update()
	level.Player.Update()
}

func (level *Level) Draw(screen *ebiten.Image) {
	level.GridSystem.Draw(screen)
	level.Player.Draw(screen)
}

func (level *Level) Position2Point(position *components.Position) image.Point {
	return image.Point{
		int(position.X) / level.Cellsize,
		int(position.Y) / level.Cellsize,
	}
}

func (level *Level) SetupGrid(game *Game) {
	// generic variant does not work here:
	// selector := generic.NewFilter1[components.Position]()
	// level.World.Batch().RemoveEntities(selector)
	// missing argument in conversion to generic.Filter1[components.Position]

	// erase all entities of previous level, if any
	posID := ecs.ComponentID[components.Position](level.World)
	selector := ecs.All(posID)
	level.World.Batch().RemoveEntities(selector)

	// get rid of any players on PlayerObserver. FIXME: remove them in grid.NewGrid()?
	playerobserver := observers.GetPlayerObserver(level.World)
	playerobserver.RemoveEntities()

	// setup world
	level.GridSystem.SetGrid(grid.NewGrid(game.World, level.Cellsize, level.Width, level.Height, level.Mapslice))
}

func LevelToSlice(game *Game, level *assets.RawLevel, tilesize int) map[image.Point]*assets.Tile {
	size := game.ScreenWidth * game.ScreenHeight
	mapslice := make(map[image.Point]*assets.Tile, size)

	for y, line := range strings.Split(string(level.Data), "\n") {
		if len(line) != game.ScreenWidth/tilesize && y < game.ScreenHeight/tilesize {
			log.Fatalf("line %d doesn't contain %d tiles, but %d",
				y, game.ScreenWidth/tilesize, len(line))
		}

		for x, char := range line {
			mapslice[image.Point{x, y}] = assets.Tiles[byte(char)]
		}
	}

	return mapslice
}