require "util"
require "defines"

-- Only purge water if we're on a ribbon map
function should_purge()
    return true
    --if glob.purge_water_should_purge ~= nil then
    --  return glob.purge_water_should_purge
    --end

    --tiles_to_check = {{-51, 0}, {51, 0}, {0, -51}, {0, 51}}
    --for i, xy in ipairs(tiles_to_check) do
    --  x, y = xy[1], xy[2]
    --  name = game.gettile(x, y).name
    --  if name == "out-of-map" then
    --      glob.purge_water_should_purge = true
    --      return glob.purge_water_should_purge
    --  end
    --end
    --glob.purge_water_should_purge = false
    --return glob.purge_water_should_purge
end

function purge_water(x1, y1, x2, y2)
    if not glob.purge_water_printed_warning then
        game.player.print('Purging water outside starting area (100x100 tiles)')
        glob.purge_water_printed_warning = true
    end
    idx = 1
    local newtiles = {}
    for x=x1,x2,1 do
        for y=y1,y2,1 do
            if (x < -50 or x > 50) or (y < -50 or y > 50) then
                name = game.gettile(x, y).name
                if name == "water" or name == "deepwater" then
                    newtiles[idx] = {name = "sand", position = {x, y}}
                    idx = idx + 1
                end
            end
        end
    end
    game.settiles(newtiles)
end

function purge_all_water()
    for coord in game.getchunks() do
        if game.ischunkgenerated(coord) then
            x1 = coord.x * 32
            y1 = coord.y * 32
            x2 = x1 + 32
            y2 = y1 + 32
            purge_water(x1, y1, x2, y2)
        end
    end
end

game.onevent(defines.events.onchunkgenerated, function(event)
    if not should_purge() then
        return
    end

    local x1 = event.area.lefttop.x
    local y1 = event.area.lefttop.y
    local x2 = event.area.rightbottom.x
    local y2 = event.area.rightbottom.y
    purge_water(x1, y1, x2, y2)
end)

game.onload(function()
    if not should_purge() then
        return
    end
    purge_all_water()
end)