package main

import (
	"flag"
	"log"
	"math"
	"os"
	"path/filepath"

	"github.com/faiface/pixel"
	"github.com/faiface/pixel/pixelgl"
	"golang.org/x/image/colornames"

	"ur.gs/ordoor/internal/conv"
	"ur.gs/ordoor/internal/data"
	"ur.gs/ordoor/internal/maps"
	"ur.gs/ordoor/internal/sets"
	"ur.gs/ordoor/internal/ui"
)

var (
	gamePath = flag.String("game-path", "./orig", "Path to a WH40K: Chaos Gate installation")
	mapFile  = flag.String("map", "", "Prefix path to a .map file, e.g. ./orig/Maps/Chapter01.MAP")
	txtFile  = flag.String("txt", "", "Prefix path to a .txt file, e.g. ./orig/Maps/Chapter01.txt")
)

type env struct {
	gameMap *maps.GameMap
	set     *sets.MapSet
	objects map[string]*conv.Object
	sprites map[string][]*pixel.Sprite
}

type state struct {
	env *env

	step int

	cam    pixel.Matrix
	camPos pixel.Vec

	zoom float64
	rot  float64

	zIdx int
}

func main() {
	flag.Parse()

	if *gamePath == "" || *mapFile == "" || *txtFile == "" {
		flag.Usage()
		os.Exit(1)
	}

	gameMap, err := maps.LoadGameMapByFiles(*mapFile, *txtFile)
	if err != nil {
		log.Fatalf("Couldn't load map file: %v", err)
	}

	setFile := filepath.Join(*gamePath, "Sets", gameMap.MapSetFilename())
	log.Println(setFile)
	mapSet, err := sets.LoadSet(setFile)
	if err != nil {
		log.Fatalf("Couldn't load set file %s: %v", setFile, err)
	}

	objects := make(map[string]*conv.Object)

	for _, name := range mapSet.Palette {
		objFile := filepath.Join(*gamePath, "Obj", name+".obj")
		obj, err := data.LoadObject(objFile)
		if err != nil {
			log.Fatalf("Failed to load %s: %v", name, err)
		}

		objects[name] = conv.ConvertObject(obj, name)
	}

	env := &env{gameMap: gameMap, set: mapSet, objects: objects}

	// The main thread now belongs to pixelgl
	pixelgl.Run(env.run)
}

func (e *env) run() {
	win, err := ui.NewWindow("View Map " + *mapFile)
	if err != nil {
		log.Fatal("Couldn't create window: %v", err)
	}

	pWin := win.PixelWindow
	state := &state{
		env: e,
		//		camPos: pixel.V(0, float64(-pWin.Bounds().Size().Y)),
		//		camPos: pixel.V(float64(3700), float64(0)),
		zoom: 1.0,
		rot:  0.785,
	}
	pWin.SetSmooth(true)

	win.Run(func() {
		oldState := *state
		state = state.runStep(pWin)

		if oldState != *state || oldState.step == 0 {
			log.Printf("zoom=%.2f rot=%.4f zIdx=%v camPos=%#v", state.zoom, state.rot, state.zIdx, state.camPos)
			state.present(pWin)
		}

		state.step += 1
	})
}

func (e *env) getSprite(palette []string, ref maps.ObjRef) (*conv.Sprite, *conv.Object) {
	if ref.Index() >= len(palette) {
		log.Printf("Palette too small: %v requested", ref.Index())
		return nil, nil
	}

	name := palette[ref.Index()]

	obj := e.objects[name]
	if obj == nil {
		log.Printf("Failed to find surface sprite %#v -> %q", ref, name)
		return nil, nil
	}

	if ref.Frame() >= len(obj.Sprites) {
		log.Printf("Out-of-index sprite %v requested for %v", ref.Frame(), name)
		return nil, obj
	}

	return &obj.Sprites[ref.Frame()], obj
}

var (
	cellWidth  = 64.0 // I think, anyway
	cellLength = 64.0
)

// TODO: build all the sprites in the set into a single spritesheet so we can
// use pixel.Batch
func (s *state) present(pWin *pixelgl.Window) {
	gameMap := s.env.gameMap

	pWin.Clear(colornames.Black)

	center := pWin.Bounds().Center()

	cam := pixel.IM
	cam = cam.ScaledXY(center, pixel.Vec{1.0, -1.0}) // invert the Y axis
	cam = cam.Scaled(pixel.ZV, s.zoom)               // apply current zoom factor
	cam = cam.Moved(center.Sub(s.camPos))            // Make it central
	//	cam = cam.Rotated(center.Sub(s.camPos), s.rot)  // Apply isometric angle
	s.cam = cam
	pWin.SetMatrix(cam)

	// TODO: bounds clipping
	z := int(s.zIdx)
	for y := int(gameMap.MinLength); y < int(gameMap.MaxLength); y++ {
		for x := int(gameMap.MinWidth); x < int(gameMap.MaxWidth); x++ {

			cell := gameMap.Cells.At(x, y, z)

			surfaceSprite, _ := s.env.getSprite(s.env.set.SurfacePalette, cell.Surface)
			centerSprite, _ := s.env.getSprite(s.env.set.CenterPalette, cell.Center)

			fX := float64(x)
			fY := float64(y)

			xPos := fX * cellWidth
			yPos := fY * cellLength

			// The rotation translates the rectangular coordinates to diamond
			// ones \o/
			// FIXME: these are off by a bit
			orig := pixel.V(xPos, yPos)
			iso := pixel.V(orig.X-orig.Y, (orig.X+orig.Y)/2.0)

			if surfaceSprite != nil {
				surfaceSprite.Spr.Draw(pWin, pixel.IM.Moved(iso))
			}

			if centerSprite != nil {
				centerSprite.Spr.Draw(pWin, pixel.IM.Moved(iso))
			}
		}
	}
}

func (s *state) runStep(pWin *pixelgl.Window) *state {
	newState := *s
	newState.handleKeys(pWin)

	return &newState
}

func (s *state) handleKeys(pWin *pixelgl.Window) {
	if pWin.Pressed(pixelgl.KeyLeft) {
		s.camPos.X -= 64
	}

	if pWin.Pressed(pixelgl.KeyRight) {
		s.camPos.X += 64
	}

	if pWin.Pressed(pixelgl.KeyDown) {
		s.camPos.Y -= 64
	}

	if pWin.Pressed(pixelgl.KeyUp) {
		s.camPos.Y += 64
	}

	for i := 1; i <= 7; i++ {
		if pWin.JustPressed(pixelgl.Key0 + pixelgl.Button(i)) {
			s.zIdx = i - 1
		}
	}

	if pWin.Pressed(pixelgl.KeyMinus) {
		s.rot -= 0.001
	}

	if pWin.Pressed(pixelgl.KeyEqual) {
		s.rot += 0.001
	}

	// Zoom in and out with the mouse wheel
	s.zoom *= math.Pow(1.2, pWin.MouseScroll().Y)
}