-- Aseprite layer normalizer for Spine tag workflow.
-- Usage: open a sprite, then File > Scripts > Rescan Scripts, run this script.
-- It renames Eyes/Mouth/Body/Accessory/Hand/Emote groups and their child layers to [slot:] / [skin:] tags.

local spr = app.activeSprite
if not spr then
  app.alert("No active sprite.")
  return
end

local warnings = {}

local function warn(message)
  table.insert(warnings, message)
end

local function stripTags(name)
  local cleaned = name:gsub("%s*%[[^%]]+%]", "")
  cleaned = cleaned:gsub("^%s+", ""):gsub("%s+$", "")
  return cleaned
end

local function taggedName(base, tag)
  return base .. " [" .. tag .. "]"
end

local function lower(name)
  return string.lower(stripTags(name))
end

local function findTopGroup(baseName)
  local target = string.lower(baseName)
  for _, layer in ipairs(spr.layers) do
    if layer.isGroup and lower(layer.name) == target then
      return layer
    end
  end
  return nil
end

local function findChildLayerByBase(parent, baseName)
  local target = string.lower(baseName)
  for _, layer in ipairs(parent.layers) do
    if lower(layer.name) == target then
      return layer
    end
  end
  return nil
end

local function renameIdleChildrenToNormal(parent, context)
  for _, layer in ipairs(parent.layers) do
    if layer.isGroup and lower(layer.name) == "idle" then
      warn(context .. ": renamed skin folder '" .. layer.name .. "' to 'Normal'.")
      layer.name = "Normal"
    end
  end
end

local function createLayerInGroup(parent, name)
  local layer = spr:newLayer()
  local moved = pcall(function()
    layer.parent = parent
  end)
  if not moved or layer.parent ~= parent then
    warn("Could not move copied layer '" .. name .. "' under '" .. stripTags(parent.name) .. "'; your Aseprite build may not support setting Layer.parent from scripts.")
  end
  layer.name = name
  return layer
end

local function copyLayerToGroup(source, parent, name)
  local copy = createLayerInGroup(parent, name)
  copy.opacity = source.opacity
  copy.blendMode = source.blendMode
  copy.isVisible = source.isVisible
  for _, cel in ipairs(source.cels) do
    local image = cel.image:clone()
    local newCel = spr:newCel(copy, cel.frame, image, cel.position)
    newCel.opacity = cel.opacity
  end
  return copy
end

local function levenshtein(a, b)
  local lenA, lenB = #a, #b
  local matrix = {}
  for i = 0, lenA do
    matrix[i] = {[0] = i}
  end
  for j = 0, lenB do
    matrix[0][j] = j
  end
  for i = 1, lenA do
    for j = 1, lenB do
      local cost = (a:sub(i, i) == b:sub(j, j)) and 0 or 1
      local deletion = matrix[i - 1][j] + 1
      local insertion = matrix[i][j - 1] + 1
      local substitution = matrix[i - 1][j - 1] + cost
      matrix[i][j] = math.min(deletion, insertion, substitution)
    end
  end
  return matrix[lenA][lenB]
end

local function scoreName(name, target)
  local n = lower(name)
  local t = string.lower(target)
  if n == t then return 0 end
  if n:find(t, 1, true) then return 1 end
  if t:find(n, 1, true) then return 2 end
  return levenshtein(n, t)
end

local function normalizeExpectedChildren(parent, expected, required, context, excluded)
  excluded = excluded or {}
  local used = {}
  for _, expectedName in ipairs(expected) do
    local exact = findChildLayerByBase(parent, expectedName)
    if exact and not used[exact] then
      exact.name = expectedName
      used[exact] = true
    end
  end

  for _, expectedName in ipairs(expected) do
    if not findChildLayerByBase(parent, expectedName) then
      local bestLayer = nil
      local bestScore = 999
      for _, layer in ipairs(parent.layers) do
        if not used[layer] and not excluded[lower(layer.name)] then
          local s = scoreName(layer.name, expectedName)
          if s < bestScore then
            bestScore = s
            bestLayer = layer
          end
        end
      end
      if bestLayer and bestScore <= 3 then
        warn(context .. ": renamed likely typo '" .. bestLayer.name .. "' to '" .. expectedName .. "'.")
        bestLayer.name = expectedName
        used[bestLayer] = true
      elseif required[expectedName] then
        warn(context .. ": missing required layer '" .. expectedName .. "'.")
      end
    end
  end
end

local function normalizeEyes()
  local group = findTopGroup("Eyes")
  if not group then
    warn("Missing top group: Eyes")
    return
  end
  group.name = taggedName("Eyes", "slot:Eyes")
  renameIdleChildrenToNormal(group, "Eyes")
  local normal = findChildLayerByBase(group, "Normal")

  for _, state in ipairs(group.layers) do
    if state.isGroup then
      local stateName = stripTags(state.name)
      state.name = taggedName(stateName, "skin:Eyes/" .. stateName)
      normalizeExpectedChildren(state, {"Brow", "Open", "Close", "Pupil"}, {Open = true, Close = true}, "Eyes/" .. stateName)
      for _, expectedName in ipairs({"Open", "Close"}) do
        if not findChildLayerByBase(state, expectedName) then
          local source = normal and findChildLayerByBase(normal, expectedName)
          if source then
            copyLayerToGroup(source, state, expectedName)
            warn("Eyes/" .. stateName .. ": copied missing '" .. expectedName .. "' from Eyes/Normal.")
          else
            warn("Eyes/" .. stateName .. ": cannot copy missing '" .. expectedName .. "' because Eyes/Normal lacks it.")
          end
        end
      end

      for _, layer in ipairs(state.layers) do
        local base = stripTags(layer.name)
        if base == "Pupil" then
          layer.name = taggedName("Pupil", "slot:Pupil")
        elseif base == "Brow" then
          layer.name = taggedName("Brow", "slot:Brow")
        else
          layer.name = taggedName(base, "slot:Eyes")
        end
      end
    end
  end
end

local function tagMouthLayers(state)
  for _, layer in ipairs(state.layers) do
    local base = stripTags(layer.name)
    if base == "Mustache" then
      layer.name = taggedName("Mustache", "slot:Mustache")
    else
      layer.name = taggedName(base, "slot:Mouth")
    end
  end
end

local function normalizeMouthState(state, context)
  local byIndex = {}
  for _, layer in ipairs(state.layers) do
    local base = stripTags(layer.name)
    local index = base:match("[_%- ]([012])%D*$") or base:match("[_%- ]0([012])%D*$")
    if index then
      local target = "Lips_0" .. index
      if not byIndex[target] then
        byIndex[target] = layer
      else
        warn(context .. ": duplicate candidate for " .. target .. " ('" .. layer.name .. "').")
      end
    end
  end

  for i = 0, 2 do
    local target = "Lips_0" .. i
    if byIndex[target] then
      if stripTags(byIndex[target].name) ~= target then
        warn(context .. ": renamed '" .. byIndex[target].name .. "' to '" .. target .. "'.")
      end
      byIndex[target].name = target
    end
  end

  normalizeExpectedChildren(state, {"Lips_00", "Lips_01", "Lips_02"}, {Lips_00 = true, Lips_01 = true, Lips_02 = true}, context, {mustache = true})
  tagMouthLayers(state)
end

local function nearestMouthLayer(state, targetIndex)
  local bestLayer = nil
  local bestDistance = 999
  for i = 0, 2 do
    local layer = findChildLayerByBase(state, "Lips_0" .. i)
    if layer then
      local distance = math.abs(i - targetIndex)
      if distance < bestDistance then
        bestDistance = distance
        bestLayer = layer
      end
    end
  end
  return bestLayer
end

local function fillMissingMouthLayers(state, context)
  for i = 0, 2 do
    local target = "Lips_0" .. i
    if not findChildLayerByBase(state, target) then
      local source = nearestMouthLayer(state, i)
      if source then
        copyLayerToGroup(source, state, target)
        warn(context .. ": copied nearest layer '" .. stripTags(source.name) .. "' to fill missing '" .. target .. "'.")
      else
        warn(context .. ": cannot fill missing '" .. target .. "' because no Lips layer exists.")
      end
    end
  end
end

local function normalizeMouth()
  local group = findTopGroup("Mouth")
  if not group then
    warn("Missing top group: Mouth")
    return
  end
  group.name = taggedName("Mouth", "slot:Mouth")
  renameIdleChildrenToNormal(group, "Mouth")

  for _, state in ipairs(group.layers) do
    if state.isGroup then
      local stateName = stripTags(state.name)
      state.name = taggedName(stateName, "skin:Mouth/" .. stateName)
      normalizeMouthState(state, "Mouth/" .. stateName)
      fillMissingMouthLayers(state, "Mouth/" .. stateName)
      tagMouthLayers(state)
    end
  end
end

local function normalizeBody()
  local group = findTopGroup("Body")
  if not group then
    warn("Missing top group: Body")
    return
  end

  group.name = taggedName("Body", "slot:Body")
  renameIdleChildrenToNormal(group, "Body")

  for _, skin in ipairs(group.layers) do
    if skin.isGroup then
      local skinName = stripTags(skin.name)
      skin.name = taggedName(skinName, "skin:Body/" .. skinName)

      for _, layer in ipairs(skin.layers) do
        local base = stripTags(layer.name)
        layer.name = taggedName(base, "slot:Body")
      end
    end
  end
end

local function normalizeOptionalSlotGroup(groupName, slotName)
  local group = findTopGroup(groupName)
  if not group then
    return
  end

  group.name = taggedName(groupName, "slot:" .. slotName)
  for _, layer in ipairs(group.layers) do
    local base = stripTags(layer.name)
    layer.name = taggedName(base, "slot:" .. slotName)
  end
end

local function normalizeAccessory()
  local group = findTopGroup("Accessory")
  if not group then
    warn("Missing top group: Accessory")
    return
  end

  group.name = taggedName("Accessory", "slot:Accessory")
  renameIdleChildrenToNormal(group, "Accessory")

  for _, skin in ipairs(group.layers) do
    if skin.isGroup then
      local skinName = stripTags(skin.name)
      skin.name = taggedName(skinName, "skin:Body/" .. skinName)

      for _, layer in ipairs(skin.layers) do
        local base = stripTags(layer.name)
        layer.name = taggedName(base, "slot:Accessory")
      end
    else
      local base = stripTags(skin.name)
      skin.name = taggedName(base, "slot:Accessory")
      warn("Accessory: layer '" .. base .. "' is directly under Accessory; expected it under a Body skin folder such as Normal or Wild.")
    end
  end
end

local function normalizeHand()
  local group = findTopGroup("Hand")
  if not group then
    return
  end

  group.name = taggedName("Hand", "slot:Hand")
  renameIdleChildrenToNormal(group, "Hand")

  for _, skin in ipairs(group.layers) do
    if skin.isGroup then
      local skinName = stripTags(skin.name)
      skin.name = taggedName(skinName, "skin:Body/" .. skinName)

      for _, layer in ipairs(skin.layers) do
        local base = stripTags(layer.name)
        layer.name = taggedName(base, "slot:Hand")
      end
    else
      local base = stripTags(skin.name)
      skin.name = taggedName(base, "slot:Hand")
      warn("Hand: layer '" .. base .. "' is directly under Hand; expected it under a Body skin folder such as Normal or Wild.")
    end
  end
end

app.transaction("Normalize Spine Tags", function()
  normalizeEyes()
  normalizeMouth()
  normalizeBody()
  normalizeAccessory()
  normalizeHand()
  normalizeOptionalSlotGroup("Emote_F", "Emote_F")
  normalizeOptionalSlotGroup("Emote_B", "Emote_B")
end)

if #warnings > 0 then
  app.alert({
    title = "Spine tag normalization finished with warnings",
    text = warnings
  })
else
  app.alert("Spine tag normalization finished with no warnings.")
end