local heightmap = require "lib.heightmap"
local lovebird = require "lib.lovebird"
local lume = require "lib.lume"

local map = {}

local biomes = {
  water = {
    altitude = {min = 0, max = 0.2},
    color = {0, 0, 1, 1},
  },
  sand = {
    altitude = {min = 0.2, max = 0.215},
    color = {1, 1, 0, 1},
  },
  grass = {
    altitude = {min = 0.215, max = 0.34},
    color = {0, 1, 0, 1},
  },
  trees = {
    altitude = {min = 0.34, max = 0.72},
    color = {0, 0.67, 0, 1},
  },
  stone = {
    altitude = {min = 0.72, max = 0.9},
    color = {0.67, 0.67, 0.67, 1},
  },
  ice = {
    altitude = {min = 0.9, max = 1},
    color = {1, 1, 1, 1}
  },
}

love.load = function()
  map.size = 150
  map.altitude = heightmap.create(map.size, map.size, 0, 1)
  map.temperature = heightmap.create(map.size, map.size, 0, 1)
  map.humidity = heightmap.create(map.size, map.size, 0, 1)

  -- if true then return end

  -- lower temperature by half height
  -- NOTE ruins "normalization" but that's fine once we have "real" numbers to work with
  for x = 0, map.temperature.w do
    for y = 0, map.temperature.h do
      map.temperature[x][y] = math.max(0, map.temperature[x][y] - map.altitude[x][y] / 2)
    end
  end
  heightmap.normalize(map.temperature, 0, 1)

  -- modify temperature by latitude
  -- TODO would be more efficient to calculate Y in outer loop, since X does not change the distance
  -- NOTE only subtracts temperature, which further "ruins normalization" and makes everything too cold:
  local center_y = map.size / 2
  for x = 0, map.temperature.w do
    for y = 0, map.temperature.h do
      local distance = math.abs(y - center_y)
      map.temperature[x][y] = lume.clamp(map.temperature[x][y] - distance / map.size / 2, 0, 1)
    end
  end
  heightmap.normalize(map.temperature, 0, 1)

  -- increase humidity by half temperature
  for x = 0, map.humidity.w do
    for y = 0, map.humidity.h do
      map.humidity[x][y] = math.min(1, map.humidity[x][y] + map.temperature[x][y] / 2)
    end
  end

  -- planetizer!
  map.terrain = {}
  local radius = (map.size / 2)^2
  for x = 0, map.size do
    map.terrain[x] = {}
    for y = 0, map.size do
      if lume.distance(x, y, map.size / 2, map.size / 2, true) < radius then
        for name, biome in pairs(biomes) do
          local value = map.altitude[x][y]
          -- this allows a non-deterministic change of terrain
          --  depending on which biome is checked first but I don't care right now]
          if value >= biome.altitude.min and value <= biome.altitude.max then
            map.terrain[x][y] = biome.color
            break
          end
        end
      end
    end
  end
end

love.update = function(dt)
  lovebird.update()
end

love.draw = function()
  local tile_size = 2

  for x = 0, map.altitude.w do
    for y = 0, map.altitude.h do
      -- raw heightmap
      local value = map.altitude[x][y]
      if value then
        love.graphics.setColor(value, value, value, 1)
        love.graphics.rectangle("fill", x * tile_size, y * tile_size, tile_size, tile_size)
      end

      -- temperature map
      local value = map.temperature[x][y]
      love.graphics.setColor(value, 0, 0, 1)
      love.graphics.rectangle("fill", map.size * tile_size + x * tile_size, y * tile_size, tile_size, tile_size)

      -- humidity map
      local value = map.humidity[x][y]
      love.graphics.setColor(0, 0, value, 1)
      love.graphics.rectangle("fill", x * tile_size, map.size * tile_size + y * tile_size, tile_size, tile_size)

      -- "naive" biomed map
      local value = map.terrain[x][y]
      if value then
        love.graphics.setColor(value)
        love.graphics.rectangle("fill", map.size * tile_size + x * tile_size, map.size * tile_size + y * tile_size, tile_size, tile_size)
      end
    end
  end
end

love.keypressed = function(key)
  if key == "escape" then
    love.event.quit()
  elseif key == "r" then
    love.load()
  end
end