extends Node

#var Downloader = preload("res://downloader.gd")
var cache = {}


var topoChunks = {}

var maxheight = 10.783
var minheight = -8.719

signal fileReady
signal chunkCached

class topoChunk:
	var chunkPos: Vector2
	var filePrefix = "user://topo/"
	var formatString = "SLDEM2015_%s_%02d%s_%02d%s_%03d_%03d_FLOAT.IMG"

	var samplesPerLine = 23040
	var lines = 15360
	var offset = 1737.4*1000
	var scaleFact = 1
	var resolution = 512
	var orientation: String = "N"
	var latMin = 0
	var latMax = 30
	var lonMin = 0
	var lonMax = 45
	var chunkCached = false
	var fileReady = false
	var file: File

	# Called when the node enters the scene tree for the first time.
	func open(latMinIN, lonMinIN):
		chunkPos = Vector2(latMinIN, lonMinIN)
		latMin = (int(latMinIN)/30) * 30
		if latMinIN >= 0:
			orientation = "N"
			latMax = latMin+30
		else:
			orientation = "S"
			latMax = latMin-30
		lonMin = (int(lonMinIN)/45) * 45
		lonMax = lonMin+45
		
		file = File.new()
		print("opening topo: "+getFilepath())
		var err = file.open(getFilepath(), File.READ)
		if err == 7:
			Downloader.download(getFilename(), "topo")
			var dl = Downloader.Download.new()
			while not dl._file_name == getFilepath():
				dl = yield(Messenger, "fileDownloaded")
			file.open(getFilepath(), File.READ)
			_fileReady()
			return true
		elif err != 0:
			push_error("error opening file err:%s" %err)
			return false
		else:
			fileReady = true
			return true
			
	func getFilename():
	# example sldem2015_512_00n_30n_000_045_float.img
	#     "%s/sldem2015_%s_%0*d%s_%0*d%s_%00*d_%00*d_float.img"
		var properties
		if orientation == "S":
			properties = [resolution, abs(latMax), orientation, abs(latMin), orientation, lonMin, lonMax]
		else:
			properties = [resolution, latMin, orientation, latMax, orientation, lonMin, lonMax]
		return formatString % properties
	
	func getFilepath():
		return filePrefix+getFilename()

	func _fileReady():
		fileReady = true
		Messenger.emit_signal("fileReady", self)

	func close():
		file.close()
		#queue_free()
	
func clear():
	cache = {}
	
func cacheChunk(chunkPos: Vector2):
	var tc
	if topoChunks.has(chunkPos.x) and topoChunks[chunkPos.x].has(chunkPos.y):
		tc = cache[chunkPos.y][chunkPos.x]
		return tc
		
	tc = topoChunk.new()
	tc.open(chunkPos.x, chunkPos.y)
	while tc.get_class() != topoChunk.get_class() and not tc.fileReady and tc.chunkPos != chunkPos:
		tc = yield(Messenger, "fileReady")
		
	var lat = chunkPos.x
	while lat <= chunkPos.x + 1.0:
		cache[lat]={}
		var line = abs(lat)*tc.resolution*tc.samplesPerLine*4
		# the origin of each .img file lies in it's upper left corner
		# so we need to read the files from the end on the northern hemisphere
		if lat >= 0:
			var origin = tc.lines*tc.samplesPerLine*4
			tc.file.seek((origin - line) + chunkPos.y*tc.resolution*4)
		else:
			tc.file.seek(line + chunkPos.y*tc.resolution*4)
		var lon = chunkPos.y
		while lon <= chunkPos.y + 1.0:
			cache[lat][lon] = tc.file.get_float()
			lon += 1.0/float(tc.resolution)
		lat += 1.0/float(tc.resolution)
	tc.chunkCached = true
	
	if not topoChunks.has(chunkPos.x):
		topoChunks[chunkPos.x] = {}
	topoChunks[chunkPos.x][chunkPos.y] = tc
	tc.file.close()
	Messenger.emit_signal("chunkCached", tc)
	return tc
	
func createHeightmap(chunkPos:Vector2):
	var minLat:float = chunkPos.x
	var minLon:float = chunkPos.y
	var maxLat:float = chunkPos.x + 1.0
	var maxLon:float = chunkPos.y + 1.0
	var idxX = 0
	var idxY = 0
	var value = 0.0	
	var heightmap = Image.new()
	heightmap.create(len(cache[cache.keys()[0]]), len(cache), false, Image.FORMAT_RF)
	heightmap.lock()
	for y in cache.keys():
		if not minLat:
			minLat = y
		for x in cache[y].keys():
			if not minLon:
				minLon = x
			value = inverse_lerp(minheight, maxheight, cache[y][x])
			heightmap.set_pixel(idxX, idxY, Color(value,0,0))#Color(cache[y][x],0,0))
			maxLon = x
			idxX += 1
		maxLat = y
		idxY += 1
		idxX = 0
	heightmap.unlock()
	var heightmapfilepath = "user://heightmap/%s:%s-%s:%s.png"%[minLat, minLon, maxLat, maxLon]
	heightmap.save_png(heightmapfilepath)
	return heightmap

func read(lat,lon):
	if cache.has(lat) and cache[lat].has(lon):
		return cache[lat][lon]
	else:
		print("out of scope!")

#func _validate(lat,lon):
#	var condition = true
#	if abs(lat) > latMax:
#		condition = false
#	if abs(lat) < latMin:
#		condition = false
#	if lon > lonMax:
#		condition = false
#	if lon < lonMin:
#		condition = false
#		
#	return condition
		
	#if abs(lat) <= latMax and abs(lat) >= latMin and lon <= lonMax and lon >= lonMin:
	#	return true
	#return false

# Called every frame. 'delta' is the elapsed time since the previous frame.
#func _process(delta):
#	pass