BNP = BNP or {}

-- Tank Mode for SuperWoW GUID nameplates.
-- Default: GREEN = hostile NPC currently targets the player, RED = another unit.
-- Normal Tank Mode is fixed: GREEN = aggro, RED = no aggro.
-- Invert Tank Colors uses two independently user-selectable colors.
-- Optional third color for in-combat NPCs temporarily unable to attack.
-- The existing two-color behavior is preserved while this option is disabled.

local GREEN_R, GREEN_G, GREEN_B = 0.00, 1.00, 0.00
local RED_R, RED_G, RED_B = 1.00, 0.00, 0.00

-- Only effects that prevent attacking; roots, snares, silence and disarm
-- alone do not qualify. Shared with the existing aura snapshot reader.
BNP.TankDisablingCC = {
  fear=true, howl_of_terror=true, banish=true, death_coil=true,
  freezing_trap_effect=true, scatter_shot=true, wyvern_sting=true,
  intimidation=true, scare_beast=true, improved_concussive_shot=true,
  polymorph=true, impact=true, psychic_scream=true, blackout=true,
  shackle_undead=true, hammer_of_justice=true, repentance=true, turn_undead=true,
  gouge=true, kidney_shot=true, cheap_shot=true, sap=true, blind=true,
  bash=true, pounce=true, hibernate=true, intimidating_shout=true,
  charge_stun=true, intercept_stun=true, concussion_blow=true, revenge_stun=true,
}

local function HasFlag(flags, mask)
  -- Lua 5.0 compatible, without requiring a bit library.
  return math.mod(math.floor(flags / mask), 2) == 1
end

local function HasCachedControl(plate, guid, now)
  -- Authoritative UNIT_AURA snapshot, independent of CC icon visibility.
  if plate.BNPClassicAuraEventDriven and plate.BNPTankControlGUID ~= guid
    and BNP.PrimeTankControlSnapshot then
    BNP:PrimeTankControlSnapshot(plate, guid, now)
  end
  if plate.BNPTankControlGUID == guid and plate.BNPClassicAuraEventDriven then
    return plate.BNPTankControlled and true or false
  end
  local cache = BNP.guidAuras and BNP.guidAuras[guid]
  local key, aura
  if cache then
    for key, aura in pairs(cache) do
      if BNP.TankDisablingCC[key] and aura.expires and aura.expires > now then return true end
    end
  end
  cache = BNP.guidLiveCCs and BNP.guidLiveCCs[guid]
  if cache then
    for key, aura in pairs(cache) do
      if BNP.TankDisablingCC[key] and (aura.eventDriven or now - (aura.lastSeen or 0) <= 0.60) then
        return true
      end
    end
  end
  return false
end

local function IsTemporarilyInactive(plate, guid, now, noTarget)
  -- One optional descriptor read covers combat, stun, confusion and fleeing,
  -- including low-health fleeing with a retained target. No tooltip/aura scan.
  local flags
  if GetUnitField then
    local ok, value = pcall(GetUnitField, guid, "flags")
    if ok and type(value) == "number" then flags = value end
  end
  local inCombat
  if flags then inCombat = HasFlag(flags, 524288)
  else inCombat = UnitAffectingCombat and UnitAffectingCombat(guid) end
  if not inCombat then return false end
  if flags and (HasFlag(flags, 262144) or HasFlag(flags, 4194304) or HasFlag(flags, 8388608)) then
    return true
  end
  return HasCachedControl(plate, guid, now) or noTarget
end

local playerGUID = nil

local function GetPlayerGUID()
  local exists, guid = UnitExists("player")
  if exists and guid then playerGUID = guid end
  return playerGUID
end

local function GetPlateGUID(plate)
  if not plate or not plate.GetName then return nil end
  -- The ClassicAPI token is stable across camera projection changes. Only
  -- use it while the API maps it back to this exact frame.
  local token = plate.BNPClassicUnitToken
  if token and BNP._ClassicUnitGUID and BNP._ClassicGetNamePlateForUnit
    and BNP._ClassicGetNamePlateForUnit(token) == plate then
    local stableGUID = BNP._ClassicUnitGUID(token)
    if stableGUID then return stableGUID end
  end
  local guid = plate:GetName(1)
  if guid and guid ~= "" then return guid end
  return nil
end

local function GetTargetGUID(guid)
  if not guid then return nil end
  local exists, targetGUID = UnitExists(guid .. "target")
  if exists then return targetGUID, false end
  return nil, true
end

local function GetBar(plate)
  return plate and (plate.healthbar or plate.healthBar) or nil
end

local function IsHostileNPC(guid)
  if not guid or not UnitExists(guid) then return false end
  if UnitIsPlayer and UnitIsPlayer(guid) then return false end
  -- Player-controlled pets/guardians are not NPC tank targets. Treating them
  -- as hostile NPCs made Tank Mode overwrite their normal pet plate colors.
  if UnitPlayerControlled and UnitPlayerControlled(guid) then return false end
  return UnitCanAttack("player", guid) and true or false
end

local function IsForeignTaggedGUID(guid)
  if not guid or not UnitExists(guid) then return false end
  if UnitCanAttack and not UnitCanAttack("player", guid) then return false end
  if not UnitIsTapped or not UnitIsTapped(guid) then return false end
  if UnitIsTappedByPlayer and UnitIsTappedByPlayer(guid) then return false end
  return true
end

local function RestoreNormalColor(plate, bar)
  -- Do not restore a cached RGB value. Outside an active Tank Mode state,
  -- Blizzard owns the NPC healthbar color completely.
  -- Only undo the new third color for this same live NPC. Never replay a
  -- cached reaction color onto a recycled, player-controlled or tagged plate.
  local guid = plate.BNPTankNoTargetActive and bar and GetPlateGUID(plate)
  if guid and guid == plate.BNPTankUnitGUID
    and IsHostileNPC(guid) and not IsForeignTaggedGUID(guid) then
    local reaction = UnitReaction and UnitReaction(guid, "player")
    if reaction then
      if reaction > 4 then bar:SetStatusBarColor(0, 1, 0, 1)
      elseif reaction == 4 then bar:SetStatusBarColor(1, 1, 0, 1)
      else bar:SetStatusBarColor(1, 0, 0, 1) end
    end
  end
  plate.BNPTankNoTargetActive = nil
  plate.BNPTankNoTargetSince = nil
  plate.BNPTankUnitGUID = nil
  plate.BNPTankColorGUID = nil
  plate.BNPTankActive = nil
  plate.BNPTankR = nil
  plate.BNPTankG = nil
  plate.BNPTankB = nil
end

local function ClearTankState(plate)
  if not plate then return end
  plate.BNPTankNoTargetActive = nil
  plate.BNPTankNoTargetSince = nil
  plate.BNPTankUnitGUID = nil
  plate.BNPTankColorGUID = nil
  plate.BNPTankActive = nil
  plate.BNPTankR = nil
  plate.BNPTankG = nil
  plate.BNPTankB = nil
end

local function ApplyTankColor(plate, bar, r, g, b)
  bar:SetStatusBarColor(r, g, b, 1)
  plate.BNPTankColorGUID = GetPlateGUID(plate)
  plate.BNPTankActive = true
  plate.BNPTankR = r
  plate.BNPTankG = g
  plate.BNPTankB = b
end

local function EnforceTankColor(plate)
  if not plate or not plate.BNPTankActive then return end
  -- Never paint a previous unit's cached color onto a recycled plate.
  if not BNP:IsTankModeEnabled() or plate.BNPTankColorGUID ~= GetPlateGUID(plate) then
    ClearTankState(plate)
    return
  end
  local bar = GetBar(plate)
  if not bar or not plate.BNPTankR then return end

  local r, g, b = bar:GetStatusBarColor()
  if math.abs(r - plate.BNPTankR) > 0.01
    or math.abs(g - plate.BNPTankG) > 0.01
    or math.abs(b - plate.BNPTankB) > 0.01 then
    bar:SetStatusBarColor(plate.BNPTankR, plate.BNPTankG, plate.BNPTankB, 1)
  end
end

function BNP:UpdateTankModePlate(plate)
  if not plate or not plate:IsShown() then return end

  local bar = GetBar(plate)
  if not bar then return end

  if not self:IsTankModeEnabled() then
    RestoreNormalColor(plate, bar)
    return
  end

  local guid = GetPlateGUID(plate)
  if not IsHostileNPC(guid) then
    -- NPC reaction colors belong to Blizzard. Never restore a stale cached
    -- Tank Mode color onto neutral/friendly/recycled nameplates.
    ClearTankState(plate)
    return
  end

  -- Foreign-tag grey has priority over Tank Mode. Previously Tank Mode wrote
  -- RED every 0.10s while fullalpha.lua restored GREY every frame, producing
  -- the visible grey/red flicker. Clear any cached tank color and let the
  -- foreign-tag renderer own the bar until the mob is ours/untapped again.
  if IsForeignTaggedGUID(guid) then
    ClearTankState(plate)
    return
  end

  local thirdColor = self:IsTankNoTargetEnabled()
  if thirdColor then
    if plate.BNPTankUnitGUID ~= guid then ClearTankState(plate) end
    plate.BNPTankUnitGUID = guid
    if UnitIsDead and UnitIsDead(guid) then
      RestoreNormalColor(plate, bar)
      return
    end
  elseif plate.BNPTankNoTargetSince or plate.BNPTankNoTargetActive then
    RestoreNormalColor(plate, bar)
  end

  local myGUID = GetPlayerGUID()
  if not myGUID then return end

  local targetGUID, noTarget = GetTargetGUID(guid)
  local now = thirdColor and GetTime()
  if thirdColor and IsTemporarilyInactive(plate, guid, now, noTarget) then
    local r, g, b = self:GetTankNoTargetColor()
    ApplyTankColor(plate, bar, r, g, b)
    plate.BNPTankNoTargetActive = true
    return
  end
  plate.BNPTankNoTargetSince = nil
  if thirdColor and not targetGUID then
    -- No active control and no readable target: relinquish the third color.
    RestoreNormalColor(plate, bar)
    return
  end
  plate.BNPTankNoTargetActive = nil
  local inverted = self:AreTankModeColorsInverted()

  if targetGUID and targetGUID == myGUID then
    if inverted then
      local r, g, b = self:GetInvertTankAggroColor()
      ApplyTankColor(plate, bar, r, g, b)
    else
      ApplyTankColor(plate, bar, GREEN_R, GREEN_G, GREEN_B)
    end
  elseif targetGUID then
    if inverted then
      local r, g, b = self:GetInvertTankNoAggroColor()
      ApplyTankColor(plate, bar, r, g, b)
    else
      ApplyTankColor(plate, bar, RED_R, RED_G, RED_B)
    end
  else
    RestoreNormalColor(plate, bar)
  end
end

function BNP:RefreshTankMode()
  local plate
  for plate in pairs(self.plates or {}) do
    if plate and plate:IsShown() then
      self:UpdateTankModePlate(plate)
    end
  end
end

function BNP:UpdateTankMode()
  local enabled = self:IsTankModeEnabled() and self:IsTankNoTargetEnabled()
  if not enabled then
    local plate
    for plate in pairs(self.plates or {}) do
      plate.BNPTankControlGUID = nil
      plate.BNPTankControlled = nil
    end
  end
  self:RefreshTankMode()
end

function BNP:InstallTankMode()
  if self.BNPTankModeInstalled then return end
  if not self.libnameplate or not self.libnameplate.OnUpdate then return end

  GetPlayerGUID()

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

    ClearTankState(current)

    local bar = GetBar(current)
    if bar and not current.BNPTankColorHooked then
      local old = bar:GetScript("OnValueChanged")
      bar:SetScript("OnValueChanged", function()
        if old then old() end
        EnforceTankColor(current)
      end)
      -- Blizzard may repaint on camera movement without changing HP. Keep
      -- only the cached color in sync here; combat/aura reads stay throttled.
      local oldUpdate = bar:GetScript("OnUpdate")
      bar:SetScript("OnUpdate", function()
        if oldUpdate then oldUpdate() end
        EnforceTankColor(current)
      end)
      current.BNPTankColorHooked = true
    end
  end)

  table.insert(self.libnameplate.OnShow, function(plate)
    local current = plate or this
    if not current then return end
    ClearTankState(current)
    current.BNPTankControlGUID = nil
    current.BNPTankControlled = nil
    BNP:UpdateTankModePlate(current)
  end)

  table.insert(self.libnameplate.OnUpdate, function(plate, elapsed)
    local current = plate or this
    if not current then return end

    -- Tank Mode is optional. Avoid all GUID/target/tap queries while it is off.
    -- Only clean an old BNP-owned state if one is still present.
    if not BNP:IsTankModeEnabled() then
      if current.BNPTankActive or current.BNPTankNoTargetSince then
        RestoreNormalColor(current, GetBar(current))
      end
      return
    end

    BNP:UpdateTankModePlate(current)
    EnforceTankColor(current)
  end)

  self.BNPTankModeInstalled = true
end