import_tileset.lua

if TilesetMode == nil then return app.alert "Use Aseprite v1.3"  end

-- Import Tilesets for every tilemap layer. 
-- Tileset name should be tiles/Tileset_*layername*.png
-- Assumes "tiles" folder accessible at ../ from aseprite file
-- For Every Tilemap Layer:
-- 1. Create empty Tilemap *layername*_2
-- 2. Import .png tileset. 
-- 3. Copy tileset pixels pixels.
-- 4. Delete all tile indices/pixels on the canvas
-- 5. Copy pixels from *layername*
-- 6. Repeat steps 2-5 for all frames
-- 7. Delete *layername*
-- 8. Rename *layername*_2 to *layername*


-- Preliminaries, going to first frame, measuring canvas...
app.command.GotoFirstFrame()
local frame = app.activeFrame
local spr = app.activeSprite
local lay = app.activeLayer
local tile_pxwidth =  spr.tilesets[1].grid.tileSize.width
local tile_pxheight =  spr.tilesets[1].grid.tileSize.height

local canvas_pxwidth = spr.width
local canvas_pxheight = spr.height
local canvas_tilewidth = canvas_pxwidth // tile_pxwidth
local canvas_tileheight = canvas_pxheight // tile_pxwidth

local fs = app.fs
local output_folder = fs.filePath(spr.filename)
local tileset_folder = "../tiles"

if not lay.isTilemap then return app.alert "No active tilemap layer" end

local function getLayer(spr, layername)
  local outlayer
  for i,layer in ipairs(spr.layers) do
    if layer.name == layername then
      outlayer = layer
      break
    end
  end
  return(outlayer)
end

local function layer_tilemap_create(newname)
  app.command.NewLayer{name=newname,ask=false,tilemap=true}
  return(app.activeLayer)
end

tilemap_oldlayer_names = {}
for i,layer in ipairs(spr.layers) do
  if layer.isTilemap then
    tilemap_oldlayer_names[#tilemap_oldlayer_names + 1] = layer.name 
  end
end

local postname = "_2"
-- Make new tilemap layers
for i = 1, (#tilemap_oldlayer_names) do
  -- print(tilemap_oldlayer_names[i])
  local tileset_filename = app.fs.joinPath(tileset_folder, "Tileset_"..tilemap_oldlayer_names[i]..".png")
  layer_tilemap_create(tilemap_oldlayer_names[i]..postname)
end

-- Copy new tiles from tilesets, and pixels from old layers
while (frame ~= nil) do
  spr = frame.sprite
  lay = app.activeLayer
  
  -- For every tileset layer
  for i = 1, (#tilemap_oldlayer_names) do
    -- get old and new tilemap layers
    local tileset_filename = app.fs.joinPath(tileset_folder, "Tileset_"..tilemap_oldlayer_names[i]..".png")
    local newlayer = getLayer(spr, tilemap_oldlayer_names[i]..postname)
    local oldlayer = getLayer(spr, tilemap_oldlayer_names[i])
    assert(newlayer ~= nil)
    assert(oldlayer ~= nil)
    oldlayer.isVisible = true
    newlayer.isVisible = true

    -- Creates new tileset by copying all pixels from tileset_filename to newlayer
    if (frame.frameNumber == 1) then
      local tileset_sprite = app.open(tileset_filename)
      local tileset_pxheight = tileset_sprite.height
      local tileset_pxwidth = tileset_sprite.width
      local tileset_tileheight = tileset_pxheight//tile_pxheight
      local tileset_splitnum = math.ceil(tileset_pxheight/canvas_pxheight)
      
      -- Copies tileset over in batches of height equal to the canvas'
      for i = 0, (tileset_splitnum-1) do
        -- Copy pixels from opened tileset file
        app.activeSprite = tileset_sprite
        selection_y = i*tile_pxheight*canvas_tileheight
        tileset_sprite.selection:deselect()
        tileset_sprite.selection:select(Rectangle(0, selection_y, tileset_pxwidth, canvas_pxheight))
        app.command.CopyMerged()
        app.activeSprite = spr
        app.activeLayer = newlayer
        app.command.TilesetMode{["mode"]="auto"}
        app.command.Paste()
        app.command.ToggleTilesMode()
        spr.selection:selectAll()
        app.command.TilesetMode{["mode"]="stack"}
        app.command.Clear()
        spr.selection:deselect()
      end
      tileset_sprite:close()
    end

    -- Copy pixels from oldlayer
    spr = app.activeSprite
    app.activeLayer = oldlayer
    spr.selection:selectAll()
    app.command.Copy()
    app.activeLayer = newlayer
    spr.selection:selectAll()
    app.command.Paste()
  end

  -- Go to next frame
  app.command.GotoNextFrame()
  frame = app.activeFrame
  if (frame.frameNumber == 1) then
    break
  end
end

-- Delete old layers
for i = 1, (#tilemap_oldlayer_names) do
  local tileset_filename = app.fs.joinPath(tileset_folder, "Tileset_"..tilemap_oldlayer_names[i]..".png")
  local newlayer = getLayer(spr, tilemap_oldlayer_names[i]..postname)
  local oldlayer = getLayer(spr, tilemap_oldlayer_names[i])
  newlayer.name = oldlayer.name
  spr:deleteLayer(oldlayer)
end