
AnchorMixin = {};

function AnchorMixin:Init(point, relativeTo, relativePoint, x, y)
	self:Set(point, relativeTo, relativePoint, x, y);
end

function AnchorMixin:Set(point, relativeTo, relativePoint, x, y)
	self.point = point;
	self.relativeTo = relativeTo;
	self.relativePoint = relativePoint;
	self.x = x;
	self.y = y;
end

function AnchorMixin:SetFromPoint(region, pointIndex)
	-- TODO: Need to check if this has no point set...probably don't want default behavior in some cases, probably
	-- want to signal something or return an invalid anchor.
	self:Set(region:GetPoint(pointIndex));
end

function AnchorMixin:Get()
	local point = self.point or "TOPLEFT";
	local relativePoint = self.relativePoint or "TOPLEFT";
	local x = self.x or 0;
	local y = self.y or 0;
	return point, self.relativeTo, relativePoint, x, y;
end

function AnchorMixin:GetRelativeTo()
	return self.relativeTo;
end


function AnchorMixin:SetPoint(region, clearAllPoints)
	if clearAllPoints then
		region:ClearAllPoints();
	end
	region:SetPoint(self:Get());
end

function AnchorMixin:SetPointWithExtraOffset(region, clearAllPoints, extraOffsetX, extraOffsetY)
	if clearAllPoints then
		region:ClearAllPoints();
	end
	local point, relativeTo, relativePoint, x, y = self:Get();
	region:SetPoint(point, relativeTo, relativePoint, x + extraOffsetX, y + extraOffsetY);
end

function CreateAnchor(point, relativeTo, relativePoint, x, y)
	return CreateAndInitFromMixin(AnchorMixin, point, relativeTo, relativePoint or point, x or 0, y or 0);
end

GridLayoutMixin = {};

-- If isVertical is true lay out columns first then rows, otherwise we lay out rows then columns
-- So for example with a stride of 2 and 6 frames this is how they would look using TopLeftToBottomRight and TopLeftToBottomRightVertical:
--
-- TopLeftToBottomRight				TopLeftToBottomRightVertical
-- 1	2							1	3	5
-- 3	4							2	4	6
-- 5	6
GridLayoutMixin.Direction = {
	TopLeftToBottomRight = { x = 1, y = -1 },
	TopRightToBottomLeft = { x = -1, y = -1 },
	BottomRightToTopLeft = { x = -1, y = 1 },
	TopLeftToBottomRightVertical = { x = 1, y = -1, isVertical = true },
	TopRightToBottomLeftVertical = { x = -1, y = -1, isVertical = true },
	LeftToRight = { x = 1, y = 0 },
	RightToLeft = { x = -1, y = 0 },
	TopToBottom = { x = 0, y = 1, isVertical = true },
	BottomToTop = { x = 0, y = -1, isVertical = true },
};

function GridLayoutMixin:Init(direction, stride, paddingX, paddingY, horizontalSpacing, verticalSpacing)
	self.direction = direction or GridLayoutMixin.Direction.TopLeftToBottomRight;
	self.stride = stride or 1;
	self.paddingX = paddingX or 0;
	self.paddingY = paddingY or 0;
	self.horizontalSpacing = horizontalSpacing;
	self.verticalSpacing = verticalSpacing;
end

function GridLayoutMixin:SetCustomOffsetFunction(func)
	self.customOffsetFunction = func;
end

function GridLayoutMixin:GetCustomOffset(row, col)
	if self.customOffsetFunction then
		return self.customOffsetFunction(row, col);
	end

	return 0, 0;
end


AnchorUtil = {};

AnchorUtil.CreateAnchor = GenerateClosure(CreateAndInitFromMixin, AnchorMixin);
AnchorUtil.CreateGridLayout = GenerateClosure(CreateAndInitFromMixin, GridLayoutMixin);

function AnchorUtil.CreateAnchorFromPoint(region, pointIndex)
	local anchor = AnchorUtil.CreateAnchor();
	anchor:SetFromPoint(region, pointIndex);
	return anchor;
end

-- For initialAnchor and layout, use AnchorUtil.CreateAnchor(...) and AnchorUtil.CreateGridLayout(...)
function AnchorUtil.GridLayout(frames, initialAnchor, layout)
	if #frames <= 0 then
		return;
	end

	local width = layout.horizontalSpacing or frames[1]:GetWidth();
	local height = layout.verticalSpacing or frames[1]:GetHeight();
	local stride = layout.stride;
	local paddingX = layout.paddingX;
	local paddingY = layout.paddingY;
	local direction = layout.direction;
	for i, frame in ipairs(frames) do
		local row = math.floor((i - 1) / stride) + 1;
		local col = (i - 1) % stride + 1;
		if direction.isVertical then
			local tempRow = row;
			row = col;
			col = tempRow;
		end
		local clearAllPoints = true;
		local customOffsetX, customOffsetY = layout:GetCustomOffset(row, col);
		local extraOffsetX = (col - 1) * (width + paddingX) * direction.x + customOffsetX;
		local extraOffsetY = (row - 1) * (height + paddingY) * direction.y + customOffsetY;
		initialAnchor:SetPointWithExtraOffset(frame, clearAllPoints, extraOffsetX, extraOffsetY);
	end
end

local function UpdateAnchorForChain(previousFrame, anchor, layout)
	local point, relativeTo, relativePoint, x, y = anchor:Get();
	if layout then
		x = layout.horizontalSpacing or x;
		y = layout.verticalSpacing or y;
	end

	local direction = (layout and layout.direction) or GridLayoutMixin.Direction.LeftToRight;

	if direction == GridLayoutMixin.Direction.LeftToRight then
		point, relativeTo, relativePoint = "LEFT", previousFrame, "RIGHT";
	elseif direction == GridLayoutMixin.Direction.RightToLeft then
		point, relativeTo, relativePoint = "RIGHT", previousFrame, "LEFT";
	elseif direction == GridLayoutMixin.Direction.TopToBottom then
		point, relativeTo, relativePoint = "TOP", previousFrame, "BOTTOM";
	elseif direction == GridLayoutMixin.Direction.BottomToTop then
		point, relativeTo, relativePoint = "BOTTOM", previousFrame, "TOP";
	end

	anchor:Set(point, relativeTo, relativePoint, x, y);
end

function AnchorUtil.ChainLayout(frames, initialAnchor, layout)
	local anchor = CreateAnchor(initialAnchor:Get());
	for i, frame in ipairs(frames) do
		anchor:SetPoint(frame);
		UpdateAnchorForChain(frame, anchor, layout);
	end
end

-- For initialAnchor and layout, use AnchorUtil.CreateAnchor(...)
function AnchorUtil.VerticalLayout(frames, initialAnchor, padding)
	if #frames <= 0 then
		return;
	end

	local clearAllPoints = true;
	initialAnchor:SetPoint(frames[1], clearAllPoints);

	padding = padding or 0;

	for index, region in CreateTableEnumerator(frames, 2) do
		region:ClearAllPoints();
		region:SetPoint("TOPLEFT", frames[index-1], "BOTTOMLEFT", 0, -padding);
	end
end

local function GetFrameSpacing(totalSize, numElements, elementSize)
	if numElements <= 1 then
		return 0;
	end

	return (totalSize - (numElements * elementSize)) / (numElements - 1);
end

local function SanitizeTotalSize(size)
	if not size or size == 0 then
		return math.huge;
	else
		return Round(size);
	end
end

-- For initialAnchor and layout, use AnchorUtil.CreateAnchor(...) and AnchorUtil.CreateGridLayout(...)
function AnchorUtil.GridLayoutFactoryByCount(factoryFunction, count, initialAnchor, layout)
	if count <= 0 then
		return;
	end

	local frames = { };
	while #frames < count do
		local frame = factoryFunction(#frames + 1);
		if not frame then
			break;
		end

		table.insert(frames, frame);
	end

	AnchorUtil.GridLayout(frames, initialAnchor, layout);

	return frames;
end

-- For initialAnchor, use AnchorUtil.CreateAnchor(...)
function AnchorUtil.GridLayoutFactory(factoryFunction, initialAnchor, totalWidth, totalHeight, overrideDirection, overridePaddingX, overridePaddingY)
	local frame = factoryFunction(1);
	if not frame then
		return;
	end

	totalWidth = SanitizeTotalSize(totalWidth);
	totalHeight = SanitizeTotalSize(totalHeight);

	-- If we have an override padding, count it in the frame width. We add a padding to totalWidth/totalHeight to account for the
	-- extra space we save for the last element which doesn't need padding.
	local width = Round(frame:GetWidth()) + (overridePaddingX or 0);
	local height = Round(frame:GetHeight()) + (overridePaddingY or 0);
	local rowSize = math.floor((totalWidth + (overridePaddingX or 0)) / width);
	local colSize = math.floor((totalHeight + (overridePaddingY or 0)) / height);

	local spacingX = overridePaddingX or GetFrameSpacing(totalWidth, rowSize, width);
	local spacingY = overridePaddingY or GetFrameSpacing(totalHeight, colSize, height);

	local frames = { frame };
	while #frames < rowSize * colSize do
		frame = factoryFunction(#frames + 1);
		if not frame then
			break;
		end

		table.insert(frames, frame);
	end

	local direction = overrideDirection or GridLayoutMixin.Direction.TopLeftToBottomRight;

	AnchorUtil.GridLayout(frames, initialAnchor, AnchorUtil.CreateGridLayout(direction, rowSize, spacingX, spacingY));
end

local function LongestCommonPrefix(s1, s2)
	if s1 == s2 then
		return s1;
	end

	for i = 1, math.min(#s1, #s2) do
		if s1:byte(i) ~= s2:byte(i) then
			return (i > 1) and s1:sub(1, i - 1) or "";
		end
	end

	-- If one string is empty and the other isn't, then we won't enter the loop.
	-- Returning the empty string since there's no common prefix.
	return "";
end

function AnchorUtil.GetRelativeToAttributeStrings(target, relativeTo, alwaysReturnAttributesIfPossible)
	-- Maybe this is just anchored to its parent and we don't need a relativeTo attribute
	local anchoredToParent = relativeTo and target:GetParent() == relativeTo;
	if not relativeTo or anchoredToParent then
		if alwaysReturnAttributesIfPossible then
			return "relativeKey", "$parent";
		end

		return;
	end

	local relativeToName = relativeTo:GetDebugName();
	local targetName = target:GetDebugName();
	local useRelativeKey = relativeToName:find(".", 1, true) ~= nil;
	local delimiter = useRelativeKey and "." or "";
	local s, e = relativeToName:find(LongestCommonPrefix(targetName, relativeToName));

	-- Found that some substring of targetName was relativeToName.
	if e ~= nil then
		local relativeToValue = relativeToName:sub(e + 1);
		local value = "$parent" .. delimiter .. relativeToValue;

		if useRelativeKey then
			return "relativeKey", value;
		else
			return "relativeTo", value;
		end
	end

	-- If there's no match here, then just use the full name of relativeTo
	return "relativeTo", relativeToName;
end

-- Mirrors an array of regions along the specified axis. For example, if horizontal, a region
-- anchored LEFT TOPLEFT 20 20 will become anchored RIGHT TOPRIGHT -20 20.
-- Mirror description format: {region = region, mirrorUV = [true, false]}
local function MirrorRegionsAlongAxis(mirrorDescriptions, exchangeables, setPointWrapper, setTexCoordsWrapper)
	for _, description in ipairs(mirrorDescriptions) do
		local exchanged = {};

		local region = description.region;
		local mirrorUV = description.mirrorUV;
		for p in pairs(exchangeables) do
			if not exchanged[p] then
				local point1, relative1, relativePoint1, x1, y1 = region:GetPointByName(p);
				if point1 then
					-- Retrieve point information for what we're replacing, if any.
					local mirrorPoint1 = exchangeables[point1];
					local point2, relative2, relativePoint2, x2, y2 = region:GetPointByName(mirrorPoint1);
					setPointWrapper(region, point1, relative1, relativePoint1, x1, y1);

					-- If we replaced a point, mirror the information to the original point.
					if point2 then
						setPointWrapper(region, point2, relative2, relativePoint2, x2, y2);
					else
						-- Otherwise, clear the original point.
						region:ClearPoint(point1);
					end

					exchanged[point1] = true;
					exchanged[mirrorPoint1] = true;
				end
			end
		end

		if mirrorUV then
			setTexCoordsWrapper(region);
		end
	end
end

local SetPointAlongAxis = function(points, region, point, relative, relativePoint, x, y)
	local mirrorPoint = points[point];
	local mirrorRelativePoint = points[relativePoint] or relativePoint;
	region:SetPoint(mirrorPoint, relative, mirrorRelativePoint, x, y);
end

local VERTICAL_MIRROR_POINTS =
{
	["TOPLEFT"] = "BOTTOMLEFT",
	["TOP"] = "BOTTOM",
	["TOPRIGHT"] = "BOTTOMRIGHT",
	["BOTTOMLEFT"] = "TOPLEFT",
	["BOTTOM"] = "TOP",
	["BOTTOMRIGHT"] = "TOPRIGHT",
	["CENTER"] = "CENTER", -- Mirrored only along x and y offsets.
	["LEFT"] = "LEFT", -- Mirrored only  along x and y offsets.
	["RIGHT"] = "RIGHT", -- Mirrored only along x and y offsets.
};

local SetPointVertical = function(region, point, relative, relativePoint, x, y)
	SetPointAlongAxis(VERTICAL_MIRROR_POINTS, region, point, relative, relativePoint, x, -y);
end;

local SetTexCoordVertical = function(region)
	local x1, y1, x2, y2, x3, y3, x4, y4 = region:GetTexCoord();
	region:SetTexCoord(x2, y2, x1, y1, x4, y4, x3, y3);
end

function AnchorUtil.MirrorRegionsAlongVerticalAxis(mirrorDescriptions)
	MirrorRegionsAlongAxis(mirrorDescriptions, VERTICAL_MIRROR_POINTS, SetPointVertical, SetTexCoordVertical);
end

local HORIZONTAL_MIRROR_POINTS =
{
	["TOPLEFT"] = "TOPRIGHT",
	["LEFT"] = "RIGHT",
	["BOTTOMLEFT"] = "BOTTOMRIGHT",
	["TOPRIGHT"] = "TOPLEFT",
	["RIGHT"] = "LEFT",
	["BOTTOMRIGHT"] = "BOTTOMLEFT",
	["CENTER"] = "CENTER", -- Mirrored only along x and y offsets.
	["TOP"] = "TOP", -- Mirrored only along x and y offsets.
	["BOTTOM"] = "BOTTOM", -- Mirrored only along x and y offsets.
};

local SetPointHorizontal = function(region, point, relative, relativePoint, x, y)
	SetPointAlongAxis(HORIZONTAL_MIRROR_POINTS, region, point, relative, relativePoint, -x, y);
end

local SetTexCoordHorizontal = function(region)
	local x1, y1, x2, y2, x3, y3, x4, y4 = region:GetTexCoord();
	region:SetTexCoord(x3, y3, x4, y4, x1, y1, x2, y2);
end

function AnchorUtil.MirrorRegionsAlongHorizontalAxis(mirrorDescriptions)
	MirrorRegionsAlongAxis(mirrorDescriptions, HORIZONTAL_MIRROR_POINTS, SetPointHorizontal, SetTexCoordHorizontal);
end

local function DebugAnchorGraph(frame, indent, visited, output)
	local indentString = "      ";
	indent = indent or indentString;
	output = output or {};
	visited = visited or {};

	if visited[frame] then
		return output;
	end

	visited[frame] = true;

	local function FormatFrame(frame)
		local color = frame:IsRectValid() and GREEN_FONT_COLOR or RED_FONT_COLOR;
		local x, y = frame:GetSize();
		local x2, y2 = frame:GetSize(true);
		return color:WrapTextInColorCode(frame:GetDebugName() .. (" calculated size <%.2f, %.2f> explicit size <%.2f, %.2f> points <%d>, scale <%.2f> effective scale <%.2f>"):format(
			x, y, x2, y2, frame:GetNumPoints(), frame:GetScale(), frame:GetEffectiveScale()));
	end
	table.insert(output, indent .. FormatFrame(frame));

	for i = 1, frame:GetNumPoints() do
		local point, relativeTo, relativePoint, x, y = frame:GetPoint(i);
		local anchorString = ("Anchor%d %s to %s at %s offset <%.2f, %.2f>"):format(i, point, relativeTo and relativeTo:GetDebugName() or "?", relativePoint, x, y);
		table.insert(output, indent .. LIGHTGRAY_FONT_COLOR:WrapTextInColorCode(anchorString));
		if relativeTo then
			DebugAnchorGraph(relativeTo, indent .. indentString, visited, output);
		end
	end

	return output;
end

function AnchorUtil.PrintAnchorGraph(frame)
	C_Log.LogMessage(table.concat(DebugAnchorGraph(frame), "\n"));
end