package game

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

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

type Map map[image.Point]*assets.Tile
type BackupMap map[image.Point]assets.Tile

type Level struct {
	Cellsize, Width, Height int
	World                   *ecs.World
	Name                    string
	Description             string
	Mapslice                Map
	BackupMapslice          Map
	GridContainer           *grid.GridContainer
	Systems                 []systems.System
	Grid                    *grid.Grid
}

func NewLevel(game *Game, cellsize int, plan *assets.RawLevel) *Level {
	systemlist := []systems.System{}

	gridcontainer := &grid.GridContainer{}

	systemlist = append(systemlist,
		systems.NewGridSystem(game.World, game.ScreenWidth, game.ScreenHeight, cellsize, plan.Background))

	systemlist = append(systemlist, systems.NewCollectibleSystem(game.World))

	systemlist = append(systemlist, systems.NewObstacleSystem(game.World, gridcontainer))

	systemlist = append(systemlist,
		systems.NewPlayerSystem(game.World, gridcontainer, game.ScreenWidth, game.ScreenHeight))

	systemlist = append(systemlist, systems.NewParticleSystem(game.World, game.Cellsize))

	systemlist = append(systemlist, systems.NewTransientSystem(game.World, gridcontainer))

	systemlist = append(systemlist, systems.NewDestroyableSystem(game.World, gridcontainer))

	systemlist = append(systemlist, systems.NewHudSystem(game.World, plan))

	mapslice, backupmap := LevelToSlice(game, plan, cellsize)

	return &Level{
		Mapslice:       mapslice,
		BackupMapslice: backupmap,
		Cellsize:       cellsize,
		World:          game.World,
		Width:          game.ScreenWidth,
		Height:         game.ScreenHeight,
		Description:    plan.Description,
		Name:           plan.Name,
		GridContainer:  gridcontainer,
		Systems:        systemlist,
	}
}

func (level *Level) Update() {
	for _, sys := range level.Systems {
		sys.Update()
	}
}

func (level *Level) Draw(screen *ebiten.Image) {
	for _, sys := range level.Systems {
		sys.Draw(screen)
	}
}

func (level *Level) RestoreMap() {
	for point, tile := range level.BackupMapslice {
		level.Mapslice[point] = tile.Clone()
	}
}

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()?
	observer := observers.GetGameObserver(level.World)
	observer.RemoveEntities()

	// get rid of possibly manipulated map
	level.RestoreMap()

	// setup world
	slog.Debug("new grid?")
	level.GridContainer.SetGrid(
		grid.NewGrid(game.World, level.Cellsize, level.Width, level.Height, level.Mapslice))
}

// parses a RawLevel and generates a mapslice from it, which is being used as grid
func LevelToSlice(game *Game, level *assets.RawLevel, tilesize int) (Map, Map) {
	size := game.ScreenWidth * game.ScreenHeight
	mapslice := make(Map, size)
	backupmap := make(Map, 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 {
			if !util.Exists(assets.Tiles, byte(char)) {
				log.Fatalf("unregistered tile type %c encountered", char)
			}

			tile := assets.Tiles[byte(char)]
			mapslice[image.Point{x, y}] = tile
			backupmap[image.Point{x, y}] = tile.Clone()
		}
	}

	return mapslice, backupmap
}