local _G = ShaguTweaks.GetGlobalEnv()
local L, T = ShaguTweaks.L, ShaguTweaks.T

local module = ShaguTweaks:register({
  title = T["Free Slot Count"],
  description = T["Shows free slot counts on the backpack button: class bag slots (top right), reagent bag slots (bottom left), and total free slots (bottom right)."],
  expansions = { ["vanilla"] = true },
  category = T["General"],
  enabled = true,
  order = 31,
})

module.enable = function(self)
  local button = MainMenuBarBackpackButton

  button.class = button:CreateFontString("Status", "LOW", "GameFontNormal")
  button.class:SetFont(STANDARD_TEXT_FONT, 14, "OUTLINE")
  button.class:SetPoint("TOPRIGHT", button, "TOPRIGHT", -2, -4)
  button.class:SetJustifyH("RIGHT")
  button.class:SetFontObject(GameFontWhite)
  local _, playerclass = UnitClass("player")
  local classcolor = RAID_CLASS_COLORS[playerclass] or { r = .5, g = .5, b = .5, a = 1 }
  button.class:SetTextColor(classcolor.r, classcolor.g, classcolor.b)

  button.reagent = button:CreateFontString("Status", "LOW", "GameFontNormal")
  button.reagent:SetFont(STANDARD_TEXT_FONT, 14, "OUTLINE")
  button.reagent:SetPoint("BOTTOMLEFT", button, "BOTTOMLEFT", 2, 4)
  button.reagent:SetJustifyH("LEFT")
  button.reagent:SetFontObject(GameFontWhite)
  button.reagent:SetTextColor(.25, .78, .92)

  button.count = button:CreateFontString("Status", "LOW", "GameFontNormal")
  button.count:SetFont(STANDARD_TEXT_FONT, 14, "OUTLINE")
  button.count:SetPoint("BOTTOMRIGHT", button, "BOTTOMRIGHT", -2, 4)
  button.count:SetJustifyH("RIGHT")
  button.count:SetFontObject(GameFontWhite)

  -- class-specific bags
  local soul    = { "Core Felcloth Bag", "D'Sak's Small bag", "Felcloth Bag", "Box of Souls", "Small Soul Pouch", "Soul Pouch" }
  local quiver  = { "Ancient Sinew Wrapped Lamina", "Harpy Hide Quiver", "Heavy Quiver", "Quickdraw Quiver", "Quiver of the Night Watch", "Ribbly's Quiver", "Hunting Quiver", "Light Leather Quiver", "Light Quiver", "Medium Quiver", "Small Quiver" }
  local pouch   = { "Gnoll Skin Bandolier", "Bandolier of the Night Watch", "Heavy Leather Ammo Pouch", "Ribbly's Bandolier", "Thick Leather Ammo Pouch", "Hunting Ammo Sack", "Medium Shot Pouch", "Small Ammo Pouch", "Small Leather Ammo Pouch", "Small Shot Pouch" }
  -- reagent bags
  local herb    = { "Cenarion Herb Bag", "Herb Pouch", "Satchel of Cenarius" }
  local ench    = { "Big Bag of Enchantment", "Enchanted Mageweave Pouch", "Enchanted Runecloth Bag" }

  local freeClass   = 0
  local freeReagent = 0

  local function findName(name, names)
    for _, bagName in ipairs(names) do
      if string.find(name, bagName) then return true end
    end
    return false
  end

  local function classSlots()
    local found, free = false, 0
    for i = 0, 4 do
      local name = GetBagName(i)
      if name and (findName(name, soul) or findName(name, quiver) or findName(name, pouch)) then
        found = true
        for slot = 1, GetContainerNumSlots(i) do
          if not GetContainerItemLink(i, slot) then free = free + 1 end
        end
      end
    end
    freeClass = free
    button.class:SetText(found and free or "")
  end

  local function reagentSlots()
    local found, free = false, 0
    for i = 0, 4 do
      local name = GetBagName(i)
      if name and (findName(name, herb) or findName(name, ench)) then
        found = true
        for slot = 1, GetContainerNumSlots(i) do
          if not GetContainerItemLink(i, slot) then free = free + 1 end
        end
      end
    end
    freeReagent = free
    button.reagent:SetText(found and free or "")
  end

  local function freeSlots()
    local free = 0
    for i = 0, 4 do
      for slot = 1, GetContainerNumSlots(i) do
        if not GetContainerItemLink(i, slot) then free = free + 1 end
      end
    end
    button.count:SetText(free - freeClass - freeReagent)
  end

  classSlots()
  reagentSlots()
  freeSlots()

  local events = CreateFrame("Frame")
  events:RegisterEvent("BAG_UPDATE")
  events:SetScript("OnEvent", function()
    classSlots()
    reagentSlots()
    freeSlots()
  end)
end