-- Version 1.1

--[[----------------------------------------------------------------
Melismatic.nw <http://nwsw.net/-f9093>

This object plugin automatically draws extender lines for matching melismas in a staff.
Only a single Melismatic object is required. Simply add it to the start of any staff
with lyrics, and the rest is automatic.

You can turn off Melismatic at any point in a staff by adding a new Melismatic object,
then assigning its Visibility to Never.

This object was inspired by the original work of Rick G on his rg_LyrEx object. The
Melimatic object would not have been possible without his original effort.

@minLength
The controls the minimum length of an extender line, in notehead units.

--]]----------------------------------------------------------------

-- our object type is passed into the script as a first paramater, which we can access using the vararg expression ...
local userObjTypeName = ...
local userObjSigName = nwc.toolbox.genSigName(userObjTypeName)

------------------------------------------------------

local function iterateMethod(o,f,i) return function() i=(i or 0)+1 return o[f](o,i) end end
local function iterateMethod2(o,f,i2,i)	return function() i=(i or 0)+1 return o[f](o,i,i2) end end

------------------------------------------------------

local function shouldExtendLyric(lt,sep)
	return (sep ~= "-") and (string.len(lt) > 0) and (lt ~= " ")
end

local function findLyricPos(o,dir)
	dir = dir or "next"
	while o:find(dir,"noteOrRest") do
		if o:isLyricPos() then return true end
	end

	return false
end

local function findMelisma(o,dir)
	dir = dir or "next"
	while o:find(dir,"noteOrRest") do
		if o:isMelisma() then return true end
	end

	return false
end

local restObjSet = {Rest=1,RestMultiBar=1}
local function isMelKiller(o)
	local t = o:objType()

	if restObjSet[t] or o:isLyricPos() then return true end

	if t == "User" then
		if o:userType() == userObjTypeName then return true end
	end

	return false
end

local function findMelKiller(o,dir)
	dir = dir or "next"
	while o:find(dir) do
		if isMelKiller(o) then return true end
	end

	return false
end

local function getExtenderDestinationX(pos1,pos2,idx)
	local xSlurTie = nil

	pos2:find(pos1)

	if not findMelKiller(pos2,"next") then pos2:find("last") end

	idx:find(pos2)
	idx:find("prior","note")
	if idx:isTieOut() or idx:isSlurOut() then
		xSlurTie = pos2:xyAnchor()-.3
	end

	pos2:find(idx)
	local x = pos2:xyRight()

	if xSlurTie then x = math.max(x,xSlurTie) end

	return x
end

------------------------------------------------------

-- we never apply Melismatic operations past another Melismatic instance
local nextMelismatic = nwc.drawpos.new()

-- we extend a melisma from drawpos to this item
local endingMelismaPos = nwc.drawpos.new()

-- we never extend a melisma through a rest position and such
local priorMelKiller = nwc.ntnidx.new()

-- keep the prior lyric position, which we set to start of staff if one does not exist
local priorLyricPos = nwc.ntnidx.new()

------------------------------------------------------

local function Melismatic_create(t)
	t.Class = 'StaffSig'
end

local function Melismatic_draw(t)
	local w = nwc.toolbox.drawStaffSigLabel(userObjSigName)
	--
	if not nwcdraw.isDrawing() then return w end

	local user = nwcdraw.user
	local drawpos = nwc.drawpos
	local idx = nwc.ntnidx
	
	-- Melismatic can be disabled by turning off its visibility
	if user:isHidden() then return end

	-- we need at least one note to work with
	if not drawpos:find("next","note") then return end

	nwcdraw.setFontClass('StaffLyric')
	local w_ref,h_ref,desc_ref =  nwcdraw.calcTextSize("Wq")
	local minLen = t.minLength

	priorMelKiller:find(drawpos)
	if not findMelKiller(priorMelKiller,"prior") then priorMelKiller:find("first") end

	priorLyricPos:find(drawpos)
	if not findLyricPos(priorLyricPos,"prior") then priorLyricPos:find("first") end

	-- we never apply Melismatic operations past another Melismatic instance, so we need to check for one
	if not nextMelismatic:find("next","user",userObjTypeName) then nextMelismatic:find("last") end

	-- first, we need to check for a hanging melisma
	if user:isAutoInsert() and not isMelKiller(drawpos) and priorLyricPos:isMelisma() and (priorLyricPos:indexOffset() >= priorMelKiller:indexOffset())  then
		endingMelismaPos:find(drawpos)
		endingMelismaPos:find("prior")
		
		local x = endingMelismaPos:xyRight()
		local x2 = math.max(getExtenderDestinationX(drawpos,endingMelismaPos,idx), x + minLen)
		local lyricRow = 0
		for lt,sep in iterateMethod2(drawpos,'lyricSyllable',-1) do
			lyricRow = lyricRow+1
			if shouldExtendLyric(lt,sep) then
				local _,ylyr = drawpos:xyLyric(lyricRow)
				ylyr = ylyr - (h_ref/2) + desc_ref
				nwcdraw.moveTo(x,ylyr)
				nwcdraw.line(x2,ylyr)
			end
		end
	end

	drawpos:reset()
	while findMelisma(drawpos) and (drawpos:indexOffset() < nextMelismatic:indexOffset()) do
		local xright = getExtenderDestinationX(drawpos,endingMelismaPos,idx)

		local lyricRow = 0
		for lt,sep in iterateMethod(drawpos,'lyricSyllable') do
			lyricRow = lyricRow+1
			if shouldExtendLyric(lt,sep) then
				local xlyr,ylyr,align = drawpos:xyLyric(lyricRow)
				local w,h,d = nwcdraw.calcTextSize(lt)
				
				if align == "Center" then w = w/2 end

				xlyr = xlyr + w + .2
				ylyr = ylyr - (h_ref/2) + desc_ref

				if (minLen > 0) or (xright > xlyr) then
					nwcdraw.moveTo(xlyr,ylyr)
					nwcdraw.line(math.max(xright,xlyr+minLen),ylyr)
				end
			end
		end
	end
end

local Melismatic_Spec = {
	{id='minLength',label='Minimum &Length',type='float',default=0.6,min=0,max=2.0,step=0.1}
	}

return {
	spec	= Melismatic_Spec,
	create	= Melismatic_create,
	width	= Melismatic_draw,
	draw	= Melismatic_draw
	}