local FILL_ATLAS = "UI-HUD-ExperienceBar-Fill-Experience"
local FRAME_ATLAS = "UI-HUD-ExperienceBar-Frame"
local BACKGROUND_ATLAS = "UI-HUD-ExperienceBar-Background"

local ACTION_BARS = {
  "MainActionBar",
  "MainMenuBar",
  "MultiBarBottomLeft",
  "MultiBarBottomRight",
  "MultiBar5",
  "MultiBar6",
  "MultiBar7",
  "StanceBar",
  "PetActionBar",
  "PossessActionBar",
}

local bar
local watch
local lastSignature
local elapsed = 0
local hooked = {}
local pushed = {}
local EnsureWatch

local function CopyTexture(dest, src)
  if not dest or not src then
    return false
  end
  if src.GetAtlas then
    local atlas = src:GetAtlas()
    if atlas and atlas ~= "" and dest.SetAtlas then
      dest:SetAtlas(atlas, false)
      return true
    end
  end
  if src.GetTexture then
    local file = src:GetTexture()
    if file then
      dest:SetTexture(file)
      if src.GetTexCoord and dest.SetTexCoord then
        dest:SetTexCoord(src:GetTexCoord())
      end
      return true
    end
  end
  return false
end

local function TrySetAtlas(texture, atlas)
  if not texture or not atlas or atlas == "" or not texture.SetAtlas then
    return false
  end
  return pcall(texture.SetAtlas, texture, atlas, false)
end

local function TrySetAtlases(texture, ...)
  for i = 1, select("#", ...) do
    if TrySetAtlas(texture, select(i, ...)) then
      return true
    end
  end
  return false
end

local FRAME_PIXEL_WIDTH = 571
local GUTTER_WIDTH_FRACTION = 2 / FRAME_PIXEL_WIDTH
local GUTTER_CENTERS = {
  56.5 / FRAME_PIXEL_WIDTH,
  113.5 / FRAME_PIXEL_WIDTH,
  170.5 / FRAME_PIXEL_WIDTH,
  227.5 / FRAME_PIXEL_WIDTH,
  284.5 / FRAME_PIXEL_WIDTH,
  341.5 / FRAME_PIXEL_WIDTH,
  398.5 / FRAME_PIXEL_WIDTH,
  455.5 / FRAME_PIXEL_WIDTH,
  512.5 / FRAME_PIXEL_WIDTH,
}

local function DisableAtlasSlice(texture)
  if texture.SetHorizTile then
    texture:SetHorizTile(false)
  end
  if texture.SetVertTile then
    texture:SetVertTile(false)
  end
  if texture.SetTextureSliceMargins then
    pcall(texture.SetTextureSliceMargins, texture, 0, 0, 0, 0)
  end
  if texture.SetTextureSliceMode and Enum and Enum.TextureSliceMode and Enum.TextureSliceMode.Stretched then
    pcall(texture.SetTextureSliceMode, texture, Enum.TextureSliceMode.Stretched)
  end
  if texture.SetSnapToPixelGrid then
    pcall(texture.SetSnapToPixelGrid, texture, true)
  end
  if texture.SetTexelSnappingBias then
    pcall(texture.SetTexelSnappingBias, texture, 0)
  end
end

local function SetRawAtlas(texture, atlas)
  if not texture or not atlas or atlas == "" then
    return false
  end
  local info = C_Texture and C_Texture.GetAtlasInfo and C_Texture.GetAtlasInfo(atlas)
  local file = info and (info.file or info.filename)
  if not info or not file or not info.leftTexCoord or not info.width or info.width == 0 then
    local applied = TrySetAtlas(texture, atlas)
    if applied then
      DisableAtlasSlice(texture)
    end
    return applied
  end
  texture:SetTexture(file)
  texture:SetTexCoord(info.leftTexCoord, info.rightTexCoord, info.topTexCoord, info.bottomTexCoord)
  DisableAtlasSlice(texture)
  return true
end

local function ApplyGutterSlice(texture, center)
  local info = C_Texture and C_Texture.GetAtlasInfo and C_Texture.GetAtlasInfo(FRAME_ATLAS)
  local file = info and (info.file or info.filename)
  if not info or not file then
    texture:SetColorTexture(0.55, 0.54, 0.5, 0.95)
    return
  end
  texture:SetTexture(file)
  local left = info.leftTexCoord or 0
  local span = (info.rightTexCoord or 1) - left
  local half = GUTTER_WIDTH_FRACTION / 2
  texture:SetTexCoord(
    left + (center - half) * span,
    left + (center + half) * span,
    info.topTexCoord or 0,
    info.bottomTexCoord or 1)
  DisableAtlasSlice(texture)
end

local function LayoutGutters(frame)
  local gutters = frame.Gutters
  local border = frame.BarFrameTexture
  if not gutters or not border then
    return
  end
  local width = border:GetWidth()
  if not width or width < 1 then
    width = frame.StatusBar and frame.StatusBar:GetWidth()
  end
  if not width or width < 1 then
    return
  end
  local sliceWidth = math.max(1, width * GUTTER_WIDTH_FRACTION)
  for i, texture in ipairs(gutters) do
    local x = width * GUTTER_CENTERS[i]
    texture:ClearAllPoints()
    texture:SetWidth(sliceWidth)
    texture:SetPoint("TOP", border, "TOPLEFT", x, 0)
    texture:SetPoint("BOTTOM", border, "BOTTOMLEFT", x, 0)
    texture:Show()
  end
end

local function SyncBarLevels(frame)
  local base = frame:GetFrameLevel()
  local status = frame.StatusBar
  if status then
    status:SetFrameStrata("LOW")
    status:SetFrameLevel(base + 1)
  end
  if frame.Overlay then
    frame.Overlay:SetFrameStrata(frame:GetFrameStrata() or "MEDIUM")
    frame.Overlay:SetFrameLevel(base + 20)
  end
end

local function FormatBarText(prof)
  if not prof.maxRank or prof.maxRank <= 0 then
    return prof.name
  end
  return string.format("%s %d/%d", prof.name, prof.rank or 0, prof.maxRank)
end

local function IsExperienceFill(status)
  local tex = status and status.GetStatusBarTexture and status:GetStatusBarTexture()
  local atlas = tex and tex.GetAtlas and tex:GetAtlas()
  return atlas and atlas:find("Experience", 1, true)
end

local function FindLiveBar(container)
  if not container or not container.bars then
    return
  end
  local fallback
  for _, candidate in pairs(container.bars) do
    if candidate and candidate.StatusBar then
      local visible = (not candidate.ShouldBeVisible or candidate:ShouldBeVisible()) and candidate:IsShown()
      if visible then
        if IsExperienceFill(candidate.StatusBar) then
          return candidate
        end
        fallback = fallback or candidate
      end
    end
  end
  return fallback or container.bars[1]
end

local function ContainerActive(container)
  if not container or not container:IsShown() then
    return false
  end
  if (container:GetAlpha() or 1) < 0.05 then
    return false
  end
  if container.bars then
    for _, candidate in pairs(container.bars) do
      if candidate and candidate.StatusBar and candidate:IsShown() then
        if not candidate.ShouldBeVisible or candidate:ShouldBeVisible() then
          return true
        end
      end
    end
    return false
  end
  return true
end

local function TopContainer()
  local top, topY
  local containers = {
    MainStatusTrackingBarContainer,
    SecondaryStatusTrackingBarContainer,
  }
  for _, container in ipairs(containers) do
    if ContainerActive(container) then
      local y = container:GetTop()
      if y and (not topY or y > topY) then
        top, topY = container, y
      end
    end
  end
  return top or MainStatusTrackingBarContainer
end

local function TextureAtlas(texture)
  if texture and texture.GetAtlas then
    local atlas = texture:GetAtlas()
    if atlas and atlas ~= "" then
      return atlas
    end
  end
end

local function FindBackgroundTexture(status, container)
  if status and status.Background then
    return status.Background
  end
  if container and container.Background then
    return container.Background
  end
  if not status then
    return
  end
  local regions = { status:GetRegions() }
  for _, region in ipairs(regions) do
    if region.GetDrawLayer and region.GetAtlas then
      local layer = region:GetDrawLayer()
      if layer == "BACKGROUND" and region ~= status:GetStatusBarTexture() then
        return region
      end
    end
  end
end

local function VisibleBar(container)
  if not container or not container.bars then
    return
  end
  for _, candidate in pairs(container.bars) do
    if candidate and candidate.StatusBar and candidate:IsShown() then
      if not candidate.ShouldBeVisible or candidate:ShouldBeVisible() then
        return candidate
      end
    end
  end
end

local function GetLiveArt()
  local main = MainStatusTrackingBarContainer
  local second = SecondaryStatusTrackingBarContainer
  local fillBar = FindLiveBar(main)
  if not fillBar or not IsExperienceFill(fillBar.StatusBar) then
    fillBar = FindLiveBar(second) or fillBar
  end
  local gutterContainer = TopContainer() or main
  local gutterBar = VisibleBar(gutterContainer) or fillBar
  local fillStatus = fillBar and fillBar.StatusBar
  local gutterStatus = gutterBar and gutterBar.StatusBar
  return {
    gutterContainer = gutterContainer,
    gutterStatus = gutterStatus,
    fillStatus = fillStatus,
    frameTexture = gutterContainer and gutterContainer.BarFrameTexture,
    frameAtlas = TextureAtlas(gutterContainer and gutterContainer.BarFrameTexture) or FRAME_ATLAS,
    fillAtlas = TextureAtlas(fillStatus and fillStatus.GetStatusBarTexture and fillStatus:GetStatusBarTexture()) or FILL_ATLAS,
    backgroundAtlas = TextureAtlas(FindBackgroundTexture(gutterStatus or fillStatus, gutterContainer)) or BACKGROUND_ATLAS,
  }
end

local function GetInsets(parent, child)
  if not parent or not child then
    return 0, 0, 0, 0
  end
  local parentLeft, parentRight = parent:GetLeft(), parent:GetRight()
  local parentTop, parentBottom = parent:GetTop(), parent:GetBottom()
  local childLeft, childRight = child:GetLeft(), child:GetRight()
  local childTop, childBottom = child:GetTop(), child:GetBottom()
  if not parentLeft or not childLeft then
    return 0, 0, 0, 0
  end
  return childLeft - parentLeft,
    parentRight - childRight,
    parentTop - childTop,
    childBottom - parentBottom
end

local function PlaceLike(dest, src, srcParent, destParent)
  dest:ClearAllPoints()
  if not src or not srcParent then
    dest:SetAllPoints(destParent)
    return
  end
  local left, right, top, bottom = GetInsets(srcParent, src)
  dest:SetPoint("TOPLEFT", destParent, "TOPLEFT", left, -top)
  dest:SetPoint("BOTTOMRIGHT", destParent, "BOTTOMRIGHT", -right, bottom)
end

local function ApplyFill(status, atlas)
  local applied = false
  local current = status:GetStatusBarTexture()
  if current and current.SetAtlas then
    applied = TrySetAtlases(current, atlas, FILL_ATLAS)
  end
  if not applied then
    status:SetStatusBarTexture("Interface\\Buttons\\WHITE8X8")
    current = status:GetStatusBarTexture()
    applied = current and TrySetAtlases(current, atlas, FILL_ATLAS)
  end
  current = status:GetStatusBarTexture()
  if current and current.SetDesaturated then
    current:SetDesaturated(true)
  end
  local r, g, b = Professor:GetBarColor()
  status:SetStatusBarColor(r, g, b, 1)
  current = status:GetStatusBarTexture()
  if current and current.SetDesaturated then
    current:SetDesaturated(true)
  end
  if current and current.SetDrawLayer then
    current:SetDrawLayer("ARTWORK", 0)
  end
end

local function ApplyXPLook(frame)
  local live = GetLiveArt()
  local gutter = live.gutterContainer
  local height = 17
  if gutter then
    height = gutter:GetHeight() or height
    frame:SetFrameStrata(gutter:GetFrameStrata() or "MEDIUM")
    frame:SetFrameLevel((gutter:GetFrameLevel() or 0) + 4)
  end
  frame:SetHeight(height)

  local status = frame.StatusBar
  PlaceLike(status, live.gutterStatus, gutter, frame)

  if not TrySetAtlases(frame.Background, live.backgroundAtlas, BACKGROUND_ATLAS) then
    frame.Background:SetColorTexture(0, 0, 0, 0.55)
  end
  frame.Background:SetAllPoints(status)

  ApplyFill(status, live.fillAtlas)

  local border = frame.BarFrameTexture
  border:SetAlpha(1)
  border:SetDrawLayer("OVERLAY", 4)
  local frameAtlas = live.frameAtlas or FRAME_ATLAS
  if not SetRawAtlas(border, frameAtlas) and live.frameTexture then
    CopyTexture(border, live.frameTexture)
  end
  DisableAtlasSlice(border)
  if live.frameTexture and live.frameTexture.GetBlendMode and border.SetBlendMode then
    border:SetBlendMode(live.frameTexture:GetBlendMode())
  end
  if live.frameTexture then
    PlaceLike(border, live.frameTexture, gutter, frame)
  else
    border:ClearAllPoints()
    border:SetAllPoints(frame)
  end

  SyncBarLevels(frame)
  LayoutGutters(frame)
end

local function CreateBar()
  local frame = CreateFrame("Frame", "ProfessorBar", UIParent)
  frame.StatusBar = CreateFrame("StatusBar", nil, frame)
  frame.Background = frame.StatusBar:CreateTexture(nil, "BACKGROUND")
  frame.Overlay = CreateFrame("Frame", nil, frame)
  frame.Overlay:SetAllPoints()
  frame.Overlay:EnableMouse(false)
  frame.BarFrameTexture = frame.Overlay:CreateTexture(nil, "OVERLAY", nil, 4)
  frame.Gutters = {}
  for i, center in ipairs(GUTTER_CENTERS) do
    local texture = frame.Overlay:CreateTexture(nil, "OVERLAY", nil, 6)
    ApplyGutterSlice(texture, center)
    frame.Gutters[i] = texture
  end
  frame.Text = frame.Overlay:CreateFontString(nil, "OVERLAY", "TextStatusBarText")
  frame.Text:SetDrawLayer("OVERLAY", 7)
  frame.Text:SetPoint("CENTER", frame.StatusBar, "CENTER", 0, 0)

  frame:EnableMouse(true)
  frame:HookScript("OnShow", function(self)
    SyncBarLevels(self)
    LayoutGutters(self)
  end)
  frame:HookScript("OnSizeChanged", function(self)
    LayoutGutters(self)
  end)
  frame:SetScript("OnEnter", function(self)
    self.Text:Show()
  end)
  frame:SetScript("OnLeave", function(self)
    if not Professor:ShouldShowText() then
      self.Text:Hide()
    end
  end)

  ApplyXPLook(frame)
  frame:Hide()
  return frame
end

local function Acquire()
  if not bar then
    bar = CreateBar()
  end
  return bar
end

local function Signature()
  local function bits(frame)
    if not frame then
      return "x"
    end
    return string.format("%s:%.1f:%.1f:%.1f:%s",
      frame:GetName() or "?",
      frame:GetLeft() or -1,
      frame:GetBottom() or -1,
      frame:GetWidth() or -1,
      frame:IsShown() and "1" or "0")
  end
  return bits(MainStatusTrackingBarContainer) .. "|" .. bits(SecondaryStatusTrackingBarContainer)
end

local function EditModeLive()
  local manager = EditModeManagerFrame
  if not manager then
    return false
  end
  if manager.IsEditModeActive then
    return manager:IsEditModeActive()
  end
  return manager.editModeActive
end

local function ClearPushes(stackTop)
  for frame in pairs(pushed) do
    if stackTop and frame.GetBottom and frame.AdjustPointsOffset then
      local bottom = frame:GetBottom()
      if bottom then
        local delta = stackTop - bottom
        if math.abs(delta) >= 0.5 then
          frame:AdjustPointsOffset(0, delta)
        end
      end
    end
    pushed[frame] = nil
  end
end

local function IsDependent(frame, other)
  if not frame or not other or frame == other then
    return false
  end
  local parent = frame:GetParent()
  while parent and parent ~= UIParent do
    if parent == other then
      return true
    end
    parent = parent:GetParent()
  end
  local points = frame:GetNumPoints() or 0
  for i = 1, points do
    local _, rel = frame:GetPoint(i)
    if rel == other then
      return true
    end
    local relParent = rel
    while relParent and relParent ~= UIParent do
      if relParent == other then
        return true
      end
      relParent = relParent:GetParent()
    end
  end
  return false
end

local function HorizontallyOverlaps(frame, left, right)
  local frameLeft, frameRight = frame:GetLeft(), frame:GetRight()
  if not frameLeft or not frameRight then
    return false
  end
  return frameRight > left + 20 and frameLeft < right - 20
end

local function NudgeActionBars(ourBar)
  if not ourBar or not ourBar:IsShown() or EditModeLive() then
    return
  end
  local stackTop = ourBar:GetBottom()
  local desiredBottom = ourBar:GetTop()
  if not stackTop or not desiredBottom then
    return
  end
  local left = ourBar:GetLeft() or 0
  local right = ourBar:GetRight() or 0
  local group, lowest = {}, nil
  for _, name in ipairs(ACTION_BARS) do
    local frame = _G[name]
    if frame and frame ~= ourBar and frame:IsVisible() and frame.AdjustPointsOffset then
      local bottom = frame:GetBottom()
      if bottom and HorizontallyOverlaps(frame, left, right) then
        local onStack = bottom >= stackTop - 8 and bottom <= stackTop + 80
        local already = math.abs(bottom - desiredBottom) < 8
        if onStack or already then
          if not lowest or bottom < lowest - 2 then
            lowest = bottom
            group = { frame }
          elseif math.abs(bottom - lowest) <= 2 then
            group[#group + 1] = frame
          end
        end
      end
    end
  end
  for _, frame in ipairs(group) do
    local dependent = false
    for _, other in ipairs(group) do
      if IsDependent(frame, other) then
        dependent = true
        break
      end
    end
    if not dependent then
      local bottom = frame:GetBottom()
      local delta = desiredBottom - bottom
      if math.abs(delta) >= 0.5 then
        frame:AdjustPointsOffset(0, delta)
      end
      pushed[frame] = true
    end
  end
end

function Professor:LayoutBars()
  local professions = self:GetVisibleProfessions()
  local anchor = TopContainer()
  local frame = Acquire()
  if #professions == 0 then
    local stackTop = frame:IsShown() and frame:GetBottom()
    frame:Hide()
    ClearPushes(stackTop)
    lastSignature = Signature()
    return
  end

  ApplyXPLook(frame)
  frame:ClearAllPoints()
  if anchor then
    frame:SetPoint("BOTTOMLEFT", anchor, "TOPLEFT", 0, 0)
    frame:SetPoint("BOTTOMRIGHT", anchor, "TOPRIGHT", 0, 0)
  else
    frame:SetPoint("BOTTOM", UIParent, "BOTTOM", 0, 80)
    frame:SetWidth(804)
  end
  frame:Show()
  LayoutGutters(frame)
  NudgeActionBars(frame)
  lastSignature = Signature()
end

function Professor:UpdateBars()
  EnsureWatch()
  local professions = self:GetVisibleProfessions()
  local frame = Acquire()
  if #professions == 0 then
    self:LayoutBars()
    return
  end
  local prof = professions[1]
  local status = frame.StatusBar
  status:SetMinMaxValues(0, prof.maximum)
  status:SetValue(prof.progress)
  frame.Text:SetText(FormatBarText(prof))
  if self:ShouldShowText() then
    frame.Text:Show()
  else
    frame.Text:Hide()
  end
  self:LayoutBars()
end

local function HookContainer(container)
  if not container or hooked[container] then
    return
  end
  hooked[container] = true
  container:HookScript("OnShow", function()
    Professor:LayoutBars()
  end)
  container:HookScript("OnHide", function()
    Professor:LayoutBars()
  end)
  container:HookScript("OnSizeChanged", function()
    Professor:LayoutBars()
  end)
end

EnsureWatch = function()
  HookContainer(MainStatusTrackingBarContainer)
  HookContainer(SecondaryStatusTrackingBarContainer)
  if watch then
    return
  end

  if EventRegistry and EventRegistry.RegisterCallback then
    pcall(EventRegistry.RegisterCallback, EventRegistry, "EditMode.Exit", function()
      Professor:LayoutBars()
    end, Professor)
  end
  if EditModeManagerFrame and EditModeManagerFrame.ExitEditMode then
    hooksecurefunc(EditModeManagerFrame, "ExitEditMode", function()
      Professor:LayoutBars()
    end)
  end
  if StatusTrackingBarManager and StatusTrackingBarManager.UpdateBarsShown then
    hooksecurefunc(StatusTrackingBarManager, "UpdateBarsShown", function()
      if bar and bar:IsShown() then
        NudgeActionBars(bar)
      end
    end)
  end

  watch = CreateFrame("Frame")
  watch:SetScript("OnUpdate", function(_, dt)
    elapsed = elapsed + dt
    if elapsed < 0.25 then
      return
    end
    elapsed = 0
    HookContainer(MainStatusTrackingBarContainer)
    HookContainer(SecondaryStatusTrackingBarContainer)
    if Signature() ~= lastSignature then
      Professor:LayoutBars()
    elseif bar and bar:IsShown() then
      NudgeActionBars(bar)
    end
  end)
end