-- Adapted from TokensWorth/ShaguTweaks-mods (MIT, original copyright GryllsAddons).

local _G = ShaguTweaks.GetGlobalEnv()
local T = ShaguTweaks.T
local API = ShaguTweaks.API

local module = ShaguTweaks:register({
  title = T["Unit Frame Abbreviated Names"],
  description = T["Abbreviates long target and target-of-target names."],
  expansions = { ["vanilla"] = true, ["tbc"] = nil },
  category = T["Unit Frames"],
  enabled = nil,
})

module.enable = function(self)
  local maxLength = 15
  local cache = {}

  local function AbbrevWord(word)
    return string.sub(word, 1, 1) .. ". "
  end

  local function GetShortName(unit)
    local name = UnitName(unit)
    if not name then
      cache[unit] = nil
      return
    end

    local cached = cache[unit]
    if cached and cached.raw == name then
      return cached.short
    end

    local short = name

    if strlen(short) > maxLength then
      short = string.gsub(short, "^(%S+) ", AbbrevWord)
    end

    if strlen(short) > maxLength then
      short = string.gsub(short, "(%S+) ", AbbrevWord)
    end

    cache[unit] = {
      raw = name,
      short = short,
    }

    return short
  end

  local function GetNameText(frame)
    if not frame then return end
    if frame.name then return frame.name end

    if frame.GetName then
      local frameName = frame:GetName()
      if frameName then
        return _G[frameName .. "Name"]
      end
    end
  end

  local function UpdateFrame(frame, unit)
    local text = GetNameText(frame)
    local name = GetShortName(unit)
    if not text or not name then return end

    -- Avoid forcing a FontString update when the displayed value is already
    -- correct. This matters most for the 250 ms target-of-target fallback.
    if not text.GetText or text:GetText() ~= name then
      text:SetText(name)
    end
  end

  local function UpdateTarget()
    UpdateFrame(TargetFrame, "target")
  end

  local function UpdateTargetTarget()
    if TargetofTargetFrame then
      UpdateFrame(TargetofTargetFrame, "targettarget")
    end
  end

  local function EventValid(name)
    return API.eventutils
      and _G.C_EventUtils
      and _G.C_EventUtils.IsEventValid
      and _G.C_EventUtils.IsEventValid(name)
  end

  local events = CreateFrame("Frame")
  events:RegisterEvent("PLAYER_ENTERING_WORLD")
  events:RegisterEvent("PLAYER_TARGET_CHANGED")

  local hasUnitTarget = EventValid("UNIT_TARGET")
  local hasUnitName = EventValid("UNIT_NAME_UPDATE")

  if hasUnitTarget then events:RegisterEvent("UNIT_TARGET") end
  if hasUnitName then events:RegisterEvent("UNIT_NAME_UPDATE") end

  events:SetScript("OnEvent", function()
    if event == "PLAYER_ENTERING_WORLD" or event == "PLAYER_TARGET_CHANGED" then
      UpdateTarget()
      UpdateTargetTarget()
    elseif event == "UNIT_TARGET" then
      if arg1 == "target" then UpdateTargetTarget() end
    elseif event == "UNIT_NAME_UPDATE" then
      if arg1 == "target" then
        UpdateTarget()
      elseif arg1 == "targettarget" then
        UpdateTargetTarget()
      end
    end
  end)

  -- Vanilla has no UNIT_TARGET event for target-of-target changes. Prefer the
  -- ClassicAPI native ticker so Lua only runs at the required 250 ms cadence,
  -- instead of entering a Lua OnUpdate handler every rendered frame. Keep the
  -- old throttled path only for older environments without C_Timer.NewTicker.
  if not hasUnitTarget then
    local function UpdateTargetTargetFallback()
      if UnitName("targettarget") then
        UpdateTargetTarget()
      end
    end

    if _G.C_Timer and type(_G.C_Timer.NewTicker) == "function" then
      _G.C_Timer.NewTicker(.25, UpdateTargetTargetFallback)
    else
      local fallback = CreateFrame("Frame")
      fallback.elapsed = 0

      fallback:SetScript("OnUpdate", function()
        this.elapsed = this.elapsed + (arg1 or 0)
        if this.elapsed < .25 then return end
        this.elapsed = 0
        UpdateTargetTargetFallback()
      end)
    end
  end

  UpdateTarget()
  UpdateTargetTarget()
end