--[[

maps – Minetest mod to render very ugly HUD maps
Copyright © 2022  Nils Dagsson Moskopp (erlehmann)

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

Dieses Programm hat das Ziel, die Medienkompetenz der Leser zu
steigern. Gelegentlich packe ich sogar einen handfesten Buffer
Overflow oder eine Format String Vulnerability zwischen die anderen
Codezeilen und schreibe das auch nicht dran.

]]--

-- blit an icon into the image unless its rect overlaps pixels that
-- have any of the stop_colors, treating a nil pixel as transparent
function tga_encoder.image:blit_icon(icon, pos, stop_colors)
	local x = pos.x
	local z = pos.z
	local overlap = false
	for i_z = 1,#icon do
		for i_x = 1,#icon[i_z] do
			local color = self.pixels[z + i_z][x + i_x][1]
			if stop_colors[color] then
				overlap = true
				break
			end
		end
		if overlap then
			break
		end
	end
	if overlap then
		return
	end
	for i_z = 1,#icon do
		for i_x = 1,#icon[i_z] do
			local color = icon[i_z][i_x][1]
			if color then
				self.pixels[z + i_z][x + i_x] = { color }
			end
		end
	end
end

maps = {}
maps.dots = {}
maps.maps = {}
maps.minp = {}
maps.maxp = {}
maps.work = {}
maps.sent = {}
maps.posx = {}
maps.posz = {}

local size = 80

local worldpath = minetest.get_worldpath()
local textures_dir = worldpath .. "/maps/"
minetest.mkdir(textures_dir)

maps.create_map = function(pos, player_name)
	local minp = vector.multiply(vector.floor(vector.divide(pos, size)), size)
	local maxp = vector.add(minp, vector.new(size - 1, size - 1, size - 1))

	local prefix, _ = minetest.pos_to_string(maxp)
	prefix, _ = prefix:gsub("%(", "")
	prefix, _ = prefix:gsub("%)", "")
	prefix, _ = prefix:gsub(",", "_")
	local filename = prefix .. ".tga"

	if maps.work[filename] then
		return
	end

	local player = minetest.get_player_by_name(player_name)

	if maps.sent[filename] then
		maps.minp[player_name] = minp
		maps.maxp[player_name] = maxp
		player:hud_change(
			maps.maps[player_name],
			"text",
			filename
		)
		return
	end

	maps.work[filename] = true

	player:hud_change(
		maps.maps[player_name],
		"text",
		"blank.png"
	)

	local emerge_callback = function(
		blockpos,
		action,
		calls_remaining
	)
		if calls_remaining > 0 then
			return
		end

		local pixels = {}
		local colormap = {
			{ 195, 175, 140 }, -- background
			{  60,  35,  16 }, -- dark line
			{ 210, 170, 130 }, -- liquid light
			{ 135,  90,  40 }, -- liquid dark
			{ 150, 105,  55 }, -- more liquid
			{ 165, 120,  70 }, -- more liquid
			{ 150, 105,  55 }, -- more liquid
			{  60,  35,  16 }, -- tree outline
			{ 150, 105,  55 }, -- tree fill
		}
		for x = 1,size,1 do
			for z = 1,size,1 do
				local color = { 0 }
				pixels[z] = pixels[z] or {}
				pixels[z][x] = color
			end
		end

		local positions = minetest.find_nodes_in_area_under_air(
			minp,
			maxp,
			"group:liquid"
		)
		for _, p in ipairs(positions) do
			local z = p.z - minp.z + 1
			local x = p.x - minp.x + 1
			pixels[z][x] = { 2 }
		end

		-- draw coastline
		for x = 1,size,1 do
			for z = 1,size,1 do
				if pixels[z][x][1] >= 2 then
					pixels[z][x] = { 2 + ( z % 2 ) } -- stripes
					if pixels[z][x][1] == 3 then
					   pixels[z][x] = { 3 + ( ( math.floor( x / 7 ) + math.floor( 1.3 * z * z ) ) % 4 ) }
					end
					if z > 1 and pixels[z-1][x][1] < 2 then
						pixels[z-1][x] = { 1 }
						pixels[z][x] = { 3 }
					end
					if z < size and pixels[z+1][x][1] < 2 then
						pixels[z+1][x] = { 1 }
						pixels[z][x] = { 3 }
					end
					if x > 1 and pixels[z][x-1][1] < 2 then
						pixels[z][x-1] = { 1 }
						pixels[z][x] = { 3 }
					end
					if x < size and pixels[z][x+1][1] < 2 then
						pixels[z][x+1] = { 1 }
						pixels[z][x] = { 3 }
					end
				end
			end
		end

		local image = tga_encoder.image(pixels)

		local positions = minetest.find_nodes_in_area_under_air(
			minp,
			maxp,
			{
				"group:leaves",
				"default:snow", -- snow-covered leaves
			}
		)
		for _, p in ipairs(positions) do
			local z = p.z - minp.z + 1
			local x = p.x - minp.x + 1
			local node = minetest.get_node({
				x=p.x,
				y=p.y - 4,
				z=p.z,
			})
			local draw_tree = (
				minetest.get_item_group(
				   node.name,
				   "tree"
			) > 0 ) and (
				z < size - 6 and
				x > 3 and
				x < size - 3
			)
			if draw_tree then
				local tree = {}
				local _ = { nil } -- transparent
				local O = { 7 } -- outline
				local F = { 8 } -- filling
				if nil ~= node.name:find("pine") then
					tree = {
						{ _, _, O, _, _ },
						{ O, O, O, O, O },
						{ O, F, F, F, O },
						{ _, O, F, O, _ },
						{ _, O, F, O, _ },
						{ _, _, O, _, _ },
					}
				else
					tree = {
						{ _, _, O, _, _ },
						{ _, _, O, _, _ },
						{ _, O, O, O, _ },
						{ O, F, F, F, O },
						{ O, F, F, F, O },
						{ O, F, F, F, O },
						{ _, O, O, O, _ },
					}
				end
				image:blit_icon(
					tree,
					{
						x = x - 3,
						z = z
					},
					{
						[3] = true,
						[4] = true,
						[5] = true,
						[6] = true,
						[7] = true,
						[8] = true
					}
				)
			end
		end

		local filepath = textures_dir .. filename
		image:save(
			filepath,
			{ colormap=colormap }
		)

		minetest.dynamic_add_media(
			filepath,
			function()
				local player =minetest.get_player_by_name(player_name)
				player:hud_change(
					maps.maps[player_name],
					"text",
					filename
				)
				maps.minp[player_name] = minp
				maps.maxp[player_name] = maxp
				maps.sent[filename] = true
				maps.work[filename] = false
			end
		)
	end

	minetest.emerge_area(
		minp,
		maxp,
		emerge_callback
	)
end

minetest.register_on_joinplayer(
	function(player)
		local player_name = player:get_player_name()
		local map_def = {
			hud_elem_type = "image",
			text = "blank.png",
			position = { x = 0.15, y = 0.90 },
			alignment = { x = 0, y = -1 },
			offset = { x = 0, y = 0 },
			scale = { x = 4, y = 4 }
		}
		local dot_def = table.copy(map_def)
		dot_def.text = "maps_x.tga" -- "player.png^[resize:4x8"
		maps.maps[player_name] = player:hud_add(map_def)
		maps.dots[player_name] = player:hud_add(dot_def)
		maps.minp[player_name] = { x=-32000, y=0, z=0 }
		maps.maxp[player_name] = { x=-32000, y=0, z=0 }
	end
)

local time_elapsed = 0

minetest.register_globalstep(
	function(dtime)
		time_elapsed = time_elapsed + dtime
		if time_elapsed < ( 1 / 30 ) then
			return -- fps limiter
		end
		local players = minetest.get_connected_players()
		for _, player in pairs(players) do
			local pos = vector.round(player:get_pos())
			local player_name = player:get_player_name()

			if (
				pos.x == maps.posx[player_name] and
				pos.z == maps.posz[player_name]
			) then
				-- continue
			else
				local minp = maps.minp[player_name]
				local maxp = maps.maxp[player_name]

				if pos.x < minp.x then
					maps.create_map(pos, player_name)
				elseif pos.x > maxp.x then
					maps.create_map(pos, player_name)
				end

				if pos.z < minp.z then
					maps.create_map(pos, player_name)
				elseif pos.z > maxp.z then
					maps.create_map(pos, player_name)
				end

				local x = (pos.x - minp.x - (size/2)) * 4
				local y = (minp.z - pos.z) * 4 - 2
				player:hud_change(
					maps.dots[player_name],
					"offset",
					{
						x = x,
						y = y,
					}
				)
				maps.posx[player_name] = pos.x
				maps.posz[player_name] = pos.z
			end
		end
	end
)