local _, MDT = ...
local twipe, tinsert, tremove, tgetn = table.wipe, table.insert, table.remove, table.getn

-- return true if a is more lower-left than b
local function is_lower_left(a, b)
  if a[1] < b[1] then return true end
  if a[1] > b[1] then return false end
  if a[2] < b[2] then return true end
  if a[2] > b[2] then return true end
  return false
end

-- return true if c is left of line a-b
local function is_left_of(a, b, c)
  local u1 = b[1] - a[1]
  local v1 = b[2] - a[2]
  local u2 = c[1] - a[1]
  local v2 = c[2] - a[2]
  return u1 * v2 - v1 * u2 < 0
end

local function convex_hull(pts)
  local lower_left = 1
  for i = 2, #pts do
    if is_lower_left(pts[i], pts[lower_left]) then lower_left = i end
  end

  local hull = {}
  local final = 1
  local tries = 0
  repeat
    table.insert(hull, lower_left)
    final = 1
    for j = 2, #pts do
      if lower_left == final or is_left_of(pts[lower_left], pts[final], pts[j]) then final = j end
    end
    lower_left = final
    tries = tries + 1
  until final == hull[1] or tries > 100 --deadlocked here otherwise?!?

  local hullpts = {}
  for _, index in ipairs(hull) do
    table.insert(hullpts, pts[index])
  end
  return hullpts
end

local function cross(a, b)
  return a[1] * b[2] - a[2] * b[1]
end

local function area(points)
  local res = cross(points[#points], points[1])
  for i = 1, #points - 1 do
    res = res + cross(points[i], points[i + 1])
  end
  return math.abs(res) / 2
end

local function centroid(pts)
  local rx = 0
  local ry = 0

  local area = area(pts)
  for i = 1, #pts - 1 do
    rx = rx + ((pts[i][1] + pts[i + 1][1]) * ((pts[i][1] * pts[i + 1][2]) - (pts[i + 1][1] * pts[i][2])))
    ry = ry + ((pts[i][2] + pts[i + 1][2]) * ((pts[i][1] * pts[i + 1][2]) - (pts[i + 1][1] * pts[i][2])))
  end
  rx = rx + ((pts[#pts][1] + pts[1][1]) * ((pts[#pts][1] * pts[1][2]) - (pts[1][1] * pts[#pts][2])))
  ry = ry + ((pts[#pts][2] + pts[1][2]) * ((pts[#pts][1] * pts[1][2]) - (pts[1][1] * pts[#pts][2])))
  rx = rx / (area * 6)
  ry = ry / (area * 6)
  return { rx, ry }
end

local function expand_polygon(poly, numCirclePoints)
  local res = {}
  local resIndex = 1
  for i = 1, #poly do
    local x = poly[i][1]
    local y = poly[i][2]
    local r = poly[i][3] * 10
    local adjustedNumPoints = math.max(1, math.floor(numCirclePoints * poly[i][3]))

    for j = 1, adjustedNumPoints do
      local cx = x + r * math.cos(2 * math.pi / adjustedNumPoints * j)
      local cy = y + r * math.sin(2 * math.pi / adjustedNumPoints * j)
      res[resIndex] = { cx, cy, r }
      resIndex = resIndex + 1
    end

  end

  return res
end

---TexturePool
local activeTextures = {}
local texturePool = {}
local function getTexture()
  local size = tgetn(texturePool)
  if size == 0 then
    return MDT.main_frame.mapPanelFrame:CreateTexture(nil, "OVERLAY")
  else
    local tex = texturePool[size]
    tremove(texturePool, size)
    tex:SetRotation(0)
    tex:SetTexCoord(0, 1, 0, 1)
    tex:ClearAllPoints()
    tex.coords = nil
    tex.points = nil
    return tex
  end
end

local function releaseTexture(tex)
  tex:Hide()
  tinsert(texturePool, tex)
end

---ReleaseAllActiveTextures
function MDT:ReleaseHullTextures()
  for k, tex in pairs(activeTextures) do
    releaseTexture(tex)
  end
  twipe(activeTextures)
end

function MDT:DrawHullCircle(x, y, size, color, layer, layerSublevel)
  local circle = getTexture()
  circle:SetDrawLayer(layer, layerSublevel)
  circle:SetTexture("Interface\\AddOns\\MythicDungeonTools\\Textures\\Circle_White")
  circle:SetVertexColor(color.r, color.g, color.b, color.a)
  circle:SetWidth(1.1 * size)
  circle:SetHeight(1.1 * size)
  circle:ClearAllPoints()
  circle:SetPoint("CENTER", MDT.main_frame.mapPanelTile1, "TOPLEFT", x, y)
  circle:Show()
  tinsert(activeTextures, circle)
end

function MDT:DrawHullLine(x, y, a, b, size, color, smooth, layer, layerSublevel, lineFactor)
  local line = getTexture()
  line:SetTexture("Interface\\AddOns\\MythicDungeonTools\\Textures\\Square_White")
  line:SetVertexColor(color.r, color.g, color.b, color.a)
  DrawLine(line, MDT.main_frame.mapPanelTile1, x, y, a, b, size, lineFactor and lineFactor or 1.1, "TOPLEFT")
  line:SetDrawLayer(layer, layerSublevel)
  line:Show()
  line.coords = { x, y, a, b }
  tinsert(activeTextures, line)
  if smooth == true then
    MDT:DrawHullCircle(x, y, size * 0.9, color, layer, layerSublevel)
  end
end

function MDT:DrawHull(vertices, pullColor, pullIdx)
  --if true then return end
  local hull = convex_hull(vertices)
  if hull then

    -- expand_polygon: higher value = more points = more expensive = smoother outlines
    hull = expand_polygon(hull, 30)

    hull = convex_hull(hull)

    for i = 1, #hull do
      local a = hull[i]
      local b = hull[1]
      if i ~= #hull then b = hull[i + 1] end
      --layerSublevel go from -8 to 7
      --we rotate through the layerSublevel to avoid collisions
      MDT:DrawHullLine(a[1], a[2], b[1], b[2], 3 * (MDT.scaleMultiplier[MDT:GetDB().currentDungeonIdx] or 1), pullColor,
        true, "ARTWORK", pullIdx % 16 - 8, 1)
    end
  end
end

local function getPullVertices(p, blips)
  local vertices = {}
  for enemyIdx, clones in pairs(p) do
    if tonumber(enemyIdx) then
      for _, cloneIdx in pairs(clones) do
        if MDT:IsCloneIncluded(enemyIdx, cloneIdx) then
          for _, blip in pairs(blips) do
            if (blip.enemyIdx == enemyIdx) and (blip.cloneIdx == cloneIdx) then
              local endPoint, endRelativeTo, endRelativePoint, endX, endY = blip:GetPoint()
              table.insert(vertices, { endX, endY, blip.normalScale })
              break
            end
          end
        end
      end
    end
  end
  return vertices
end

function MDT:DrawAllHulls(pulls)
  MDT:ReleaseHullTextures()
  local preset = MDT:GetCurrentPreset()
  local blips = MDT:GetDungeonEnemyBlips()
  local vertices
  pulls = pulls or preset.value.pulls
  for pullIdx, p in pairs(pulls) do
    local r, g, b = MDT:DungeonEnemies_GetPullColor(pullIdx, pulls)
    vertices = getPullVertices(p, blips)
    MDT:DrawHull(vertices, { r = r, g = g, b = b, a = 1 }, pullIdx)
  end
end

function MDT:FindClosestPull(x, y)
  local preset = MDT:GetCurrentPreset()
  local blips = MDT:GetDungeonEnemyBlips()
  local vertices, hull, center
  local centers = {}
  --1. construct all hulls of pulls in this sublevel
  for pullIdx, p in pairs(preset.value.pulls) do
    vertices = getPullVertices(p, blips)
    hull = convex_hull(vertices)
    --2. get centroid of each pull
    if hull and hull[#hull] then
      if #hull > 2 then
        center = centroid(hull)
        centers[pullIdx] = center
      elseif #hull == 2 then
        local x1 = hull[1][1]
        local y1 = hull[1][2]
        local x2 = hull[2][1]
        local y2 = hull[2][2]
        centers[pullIdx] = { (x1 + x2) / 2, (y1 + y2) / 2 }
      elseif #hull == 1 then
        local x1 = hull[1][1]
        local y1 = hull[1][2]
        centers[pullIdx] = { x1, y1 }
      end
    end
  end
  --3. find closest centroid
  local centerDist = math.huge
  local centerIndex
  for k, center in pairs(centers) do
    local squaredDist = (x - center[1]) ^ 2 + (y - center[2]) ^ 2
    if squaredDist < centerDist then
      centerDist = squaredDist
      centerIndex = k
    end
  end
  if centerIndex then
    return centerIndex, centers[centerIndex][1], centers[centerIndex][2]
  end

end
