BNP = BNP or {}

local MIN_SCALE = 0.50
local MAX_SCALE = 1.50
local DEFAULT_SCALE = 1.00

local function Clamp(value)
  if value < MIN_SCALE then return MIN_SCALE end
  if value > MAX_SCALE then return MAX_SCALE end
  return value
end

function BNP:GetNameplateScale()
  BNP_DB = BNP_DB or {}
  return Clamp(tonumber(BNP_DB.nameplateScale) or DEFAULT_SCALE)
end

local function EffectiveScale()
  local uiScale = 1.0
  if UIParent and UIParent.GetScale then
    uiScale = UIParent:GetScale() or 1.0
  end
  return uiScale * BNP:GetNameplateScale()
end

local function CaptureAnchorState(object, plate, wrapper)
  if not object or not object.GetPoint then return nil end

  local state = {
    object = object,
    points = {},
  }

  local count = 1
  if object.GetNumPoints then
    count = object:GetNumPoints() or 1
    if count < 1 then count = 1 end
  end

  local i
  for i = 1, count do
    local point, relativeTo, relativePoint, x, y = object:GetPoint(i)
    if point then
      if relativeTo == plate then
        relativeTo = wrapper
      end

      state.points[table.getn(state.points) + 1] = {
        point = point,
        relativeTo = relativeTo or wrapper,
        relativePoint = relativePoint or point,
        x = x or 0,
        y = y or 0,
      }
    end
  end

  return state
end

local function StateYOffset(state)
  if state and state.BNPNameAnchor and BNP.GetNameFontYOffset then
    return BNP:GetNameFontYOffset()
  end
  return 0
end

local function AnchorStateMatches(state)
  if not state or not state.object or not state.object.GetPoint then return false end

  local object = state.object
  local expectedCount = table.getn(state.points)
  local currentCount = expectedCount

  if object.GetNumPoints then
    currentCount = object:GetNumPoints() or 0
  end

  if currentCount ~= expectedCount then
    return false
  end

  local i
  for i = 1, expectedCount do
    local expected = state.points[i]
    local point, relativeTo, relativePoint, x, y = object:GetPoint(i)

    if point ~= expected.point
      or relativeTo ~= expected.relativeTo
      or relativePoint ~= expected.relativePoint
      or math.abs((x or 0) - expected.x) > 0.01
      or math.abs((y or 0) - (expected.y + StateYOffset(state))) > 0.01 then
      return false
    end
  end

  return true
end

local function RestoreAnchorState(state, wrapper)
  if not state or not state.object then return end

  local object = state.object

  if object.GetParent and object.SetParent and object:GetParent() ~= wrapper then
    object:SetParent(wrapper)
  end

  -- Do nothing in the common case. Blizzard normally only rewrites a subset
  -- of nameplate anchors while moving, most notably the level FontString.
  if AnchorStateMatches(state) then return end

  if not object.ClearAllPoints or not object.SetPoint then return end

  object:ClearAllPoints()

  local i
  for i = 1, table.getn(state.points) do
    local p = state.points[i]
    object:SetPoint(
      p.point,
      p.relativeTo or wrapper,
      p.relativePoint or p.point,
      p.x,
      p.y + StateYOffset(state)
    )
  end
end

local function SetHoverGlow(plate, shown)
  if not plate or not plate.glow then return end

  if shown then
    if plate.glow.Show then
      plate.glow:Show()
    end
  else
    if plate.glow.Hide then
      plate.glow:Hide()
    end
  end
end

-- SuperWoW exposes the attached unit GUID through nameplate:GetName(1).
-- Its SetMouseoverUnit(unit) API is specifically intended for custom unit
-- frames: set it on OnEnter and clear it on OnLeave.  BNP's scale/Y-offset
-- wrapper owns the mouse hit area, so without this bridge the client never
-- receives a real "mouseover" unit even though clicks are forwarded to the
-- original Blizzard nameplate.
local function GetPlateMouseoverUnit(plate)
  if not plate or not plate.GetName then return nil end

  local ok, unit = pcall(function() return plate:GetName(1) end)
  if not ok or not unit then return nil end

  if UnitExists then
    local existsOK, exists = pcall(UnitExists, unit)
    if existsOK and not exists then return nil end
  end

  return unit
end

local function ShowPlateTooltip(wrapper, unit)
  if not wrapper or not unit or not GameTooltip or not GameTooltip.SetUnit then return end

  -- SetMouseoverUnit() has already made "mouseover" a valid unit.  Prefer
  -- that token so tooltip addons see the same unit surface as mouseover macros.
  if GameTooltip_SetDefaultAnchor then
    GameTooltip_SetDefaultAnchor(GameTooltip, wrapper)
  elseif GameTooltip.SetOwner then
    GameTooltip:SetOwner(wrapper, "ANCHOR_CURSOR")
  end

  local ok = pcall(function() GameTooltip:SetUnit("mouseover") end)
  if not ok then
    pcall(function() GameTooltip:SetUnit(unit) end)
  end

  if GameTooltip.Show then GameTooltip:Show() end
end

local function SetWrapperMouseover(plate, wrapper)
  local unit = GetPlateMouseoverUnit(plate)
  if not unit then return end

  -- Keep ownership so a late OnLeave from an overlapping/recycled plate cannot
  -- clear the mouseover unit that a newer wrapper has just established.
  BNP.BNPMouseoverOwner = wrapper
  wrapper.BNPMouseoverUnit = unit

  if SetMouseoverUnit then
    local ok = pcall(SetMouseoverUnit, unit)
    if ok then
      ShowPlateTooltip(wrapper, unit)
    end
  end
end

local function ClearWrapperMouseover(wrapper)
  if BNP.BNPMouseoverOwner ~= wrapper then return end

  BNP.BNPMouseoverOwner = nil
  wrapper.BNPMouseoverUnit = nil

  if SetMouseoverUnit then
    pcall(SetMouseoverUnit)
  end

  if GameTooltip and GameTooltip.Hide then
    GameTooltip:Hide()
  end
end

local function SetYOffsetMouseMode(plate, wrapper, offset)
  if not plate or not wrapper then return end

  -- Always use the visual wrapper as BNP's interactive frame, including at
  -- Y Offset 0. Previously offset 0 used Blizzard's native Button while
  -- positive offsets used BNPScaleWrapper. That split mouse path caused the
  -- original Blizzard mouseover glow to disappear at offset 0.
  --
  -- Keeping clicks, hit geometry and hover feedback on the same frame also
  -- guarantees that the clickable area follows the visible plate at every
  -- configured Y offset.
  if plate.EnableMouse then
    plate:EnableMouse(false)
  end

  if wrapper.EnableMouse then
    wrapper:EnableMouse(true)
  end

  if wrapper.RegisterForClicks then
    -- Preserve the classic Blizzard nameplate mouse behavior:
    -- left click selects the unit, right click selects it and starts auto attack.
    wrapper:RegisterForClicks("LeftButtonUp", "RightButtonUp")
  end

  if not wrapper.BNPClickForwardInstalled then
    wrapper:SetScript("OnClick", function()
      -- The wrapper exists only because BNP visually offsets/scales the original
      -- Blizzard plate. Keep Blizzard's native nameplate click semantics by
      -- forwarding the ACTUAL mouse button to the original Button.
      --
      -- parent:Click() without an argument always simulates LeftButton. That was
      -- the reason right click turned into a plain target-select while BNP was
      -- enabled. Do not call AttackTarget() manually here: it toggles auto attack
      -- and is not equivalent to Blizzard's native nameplate right-click path.
      local mouseButton = arg1 or "LeftButton"
      local current = this or wrapper
      local parent = current and current.plate or plate
      if parent and parent:IsShown() and parent.Click then
        parent:Click(mouseButton)
      end
    end)
    wrapper.BNPClickForwardInstalled = true
  end

  if not wrapper.BNPMouseoverFeedbackInstalled then
    wrapper:SetScript("OnEnter", function()
      local current = this or wrapper
      local parent = current and current.plate or plate
      SetHoverGlow(parent, true)
      SetWrapperMouseover(parent, current)
    end)

    wrapper:SetScript("OnLeave", function()
      local current = this or wrapper
      local parent = current and current.plate or plate
      SetHoverGlow(parent, false)
      ClearWrapperMouseover(current)
    end)

    -- A projected nameplate can disappear/recycle while the cursor is still
    -- inside its old bounds. Clear SuperWoW's synthetic mouseover in that case
    -- as well so "mouseover" can never remain stuck on a vanished unit.
    wrapper:SetScript("OnHide", function()
      local current = this or wrapper
      ClearWrapperMouseover(current)
    end)

    wrapper.BNPMouseoverFeedbackInstalled = true
  end
end

local function ApplyWrapperOffset(plate, wrapper)
  if not plate or not wrapper then return end

  local offset = 0
  if BNP.GetNameplateYOffset then
    offset = BNP:GetNameplateYOffset()
  end

  -- Move only the child visual container. The WorldFrame-projected Blizzard
  -- nameplate itself keeps its original anchor and can continue to be
  -- repositioned by the client every frame.
  wrapper:ClearAllPoints()
  wrapper:SetPoint("TOPLEFT", plate, "TOPLEFT", 0, offset)
  wrapper:SetPoint("BOTTOMRIGHT", plate, "BOTTOMRIGHT", 0, offset)

  SetYOffsetMouseMode(plate, wrapper, offset)
end

local function EnsureScaleWrapper(plate)
  if not plate or plate.BNPScaleWrapper then return end

  local originalWidth = plate:GetWidth()
  local originalHeight = plate:GetHeight()

  local wrapper = CreateFrame("Button", nil, plate)
  wrapper:SetAllPoints(plate)
  wrapper.plate = plate
  wrapper.originalWidth = originalWidth
  wrapper.originalHeight = originalHeight
  wrapper.BNPAnchorStates = {}
  wrapper:EnableMouse(false)

  plate.BNPScaleWrapper = wrapper

  -- Capture the ORIGINAL Blizzard anchors before changing parentage.
  -- Those stored anchors become BNP's authoritative visual layout whenever
  -- Y-offset is enabled.
  if plate.healthbar then
    local state = CaptureAnchorState(plate.healthbar, plate, wrapper)
    if state then
      table.insert(wrapper.BNPAnchorStates, state)
    end

    plate.healthbar:SetParent(wrapper)
    RestoreAnchorState(state, wrapper)
    plate.healthbar:SetFrameLevel(1)
  end

  local regions = { plate:GetRegions() }
  local i, object
  for i, object in pairs(regions) do
    if object and object.SetParent then
      local state = CaptureAnchorState(object, plate, wrapper)
      if state then
        if object == plate.name then
          state.BNPNameAnchor = true
        end
        table.insert(wrapper.BNPAnchorStates, state)
      end

      object:SetParent(wrapper)
      RestoreAnchorState(state, wrapper)
    end
  end

  ApplyWrapperOffset(plate, wrapper)
end

function BNP:ApplyNameplateScale(plate)
  if not plate then return end
  EnsureScaleWrapper(plate)

  local wrapper = plate.BNPScaleWrapper
  if not wrapper then return end

  local scale = EffectiveScale()
  wrapper:SetScale(scale)
  ApplyWrapperOffset(plate, wrapper)

  -- ShaguTweaks also adjusts the original frame bounds so Blizzard's world
  -- positioning remains correct while the child visuals honor UI scale.
  plate:SetWidth(wrapper.originalWidth * scale)
  plate:SetHeight(wrapper.originalHeight * scale)
end

function BNP:ApplyNameFontYOffset(plate)
  if not plate then return end
  EnsureScaleWrapper(plate)

  local wrapper = plate.BNPScaleWrapper
  if not wrapper then return end

  local states = wrapper.BNPAnchorStates or {}
  local i
  for i = 1, table.getn(states) do
    local state = states[i]
    if state and state.BNPNameAnchor then
      RestoreAnchorState(state, wrapper)
    end
  end
end

function BNP:ApplyNameFontYOffsetAll()
  local plate
  for plate in pairs(self.plates or {}) do
    if plate then self:ApplyNameFontYOffset(plate) end
  end
end

function BNP:ApplyNameplateScaleAll()
  local plate
  for plate in pairs(self.plates) do
    self:ApplyNameplateScale(plate)
  end
end

function BNP:ApplyNameplateYOffsetAll()
  local plate
  for plate in pairs(self.plates or {}) do
    if plate then
      self:ApplyNameplateScale(plate)
    end
  end
end

function BNP:MaintainNameplateYOffset(plate)
  if not plate or not plate:IsShown() then return end
  if not self.GetNameplateYOffset or self:GetNameplateYOffset() <= 0 then return end

  EnsureScaleWrapper(plate)

  local wrapper = plate.BNPScaleWrapper
  if not wrapper then return end

  -- Never rediscover regions through plate:GetRegions() here. Once BNP moves
  -- Blizzard regions into the wrapper they are no longer guaranteed to be
  -- returned by plate:GetRegions(). Keep and maintain the original region
  -- objects captured during wrapper creation instead.
  local states = wrapper.BNPAnchorStates or {}
  local i
  for i = 1, table.getn(states) do
    RestoreAnchorState(states[i], wrapper)
  end

  ApplyWrapperOffset(plate, wrapper)
end

function BNP:SetNameplateScale(value)
  value = tonumber(value)
  if not value then
    self:Print("Usage: /bnp scale 0.5-1.5")
    return
  end

  value = Clamp(value)
  BNP_DB = BNP_DB or {}
  BNP_DB.nameplateScale = value
  self:ApplyNameplateScaleAll()

  self:Print("Nameplate scale multiplier set to " .. tostring(value) .. ".")
end

function BNP:ResetNameplateScale()
  BNP_DB = BNP_DB or {}
  BNP_DB.nameplateScale = DEFAULT_SCALE
  self:ApplyNameplateScaleAll()
  self:Print("Nameplate scale multiplier reset to 1.0 (Shagu/UI scale behavior).")
end

if BNP.libnameplate then
  table.insert(BNP.libnameplate.OnInit, function(plate)
    local current = plate or this
    if not current then return end
    BNP:ApplyNameplateScale(current)
  end)

  table.insert(BNP.libnameplate.OnShow, function(plate)
    local current = plate or this
    if not current then return end
    BNP:ApplyNameplateScale(current)
  end)
end