import '../support/glyph' as Glyph
import '../support/transform' as Transform

define GDEF_SIMPLE 1
define GDEF_LIGATURE 2
define GDEF_MARK 3

# Compatibility ligatures
define [interpretLookups gs lutns lookups] : begin
	foreach [lutn : items-of lutns] : begin
		local lut lookups.(lutn)
		if lut : interpretLookup gs lut lookups

define [interpretLookup gs lut lookups] : match lut.type
	"gsub_chaining" : begin
		local j 0
		while (j < gs.length) : begin
			local incN 1
			do : foreach [subtable : items-of lut.subtables] : begin
				local matchT subtable.match
				local ib subtable.inputBegins
				local foundMatch true
				for [local k 0] (foundMatch && k < matchT.length) [inc k] : begin
					if [not gs.(j + k - ib)]
					: then : set foundMatch false
					: else : if ([matchT.(k).indexOf gs.(j + k - ib)] < 0) : set foundMatch false
				if foundMatch : begin
					foreach [app : items-of subtable.apply] : do
						local aj : j - ib + app.at
						local alut lookups.(app.lookup)
						interpretLookupAt gs aj alut
					set incN : incN + subtable.inputEnds - subtable.inputBegins
					break nothing
			set j : j + incN
	"gsub_reverse" : begin
		local j (gs.length - 1)
		while (j >= 0) : begin
			do : foreach [subtable : items-of lut.subtables] : begin
				local matchT subtable.match
				local ib subtable.inputIndex
				local foundMatch true
				for [local k 0] (foundMatch && k < matchT.length) [inc k] : begin
					if [not gs.(j + k - ib)]
					: then : set foundMatch false
					: else : if ([matchT.(k).indexOf gs.(j + k - ib)] < 0) : set foundMatch false
				if foundMatch : begin
					set gs.(j) : subtable.to.[matchT.(ib).indexOf gs.(j)] || gs.(j)
			set j : j - 1
	"gsub_single" : begin
		for [local j 0] (j < gs.length) [inc j] : begin
			interpretLookupAt gs j lut

define [interpretLookupAt gs j lut] : match lut.type
	"gsub_single" : foreach [subtable : items-of lut.subtables] : begin
		if subtable.(gs.(j)) : begin
			set gs.(j) subtable.(gs.(j))

export : define [BuildCompatLigatures glyphs glyphList unicodeGlyphs GSUB GDEF config] : begin
	foreach [cldef : items-of config] : do
		if [not cldef.unicode] : break nothing
		if [not cldef.featureTag] : break nothing
		if [not cldef.sequence] : break nothing

		local feature null
		foreach [fn : items-of GSUB.languages.'DFLT_DFLT'.features]
			if (cldef.featureTag === [fn.slice 0 4]) : set feature GSUB.features.(fn)

		if [not feature] : break nothing

		local gnames {}
		for [local j 0] [j < cldef.sequence.length] [inc j] : begin
			if [not unicodeGlyphs.[cldef.sequence.charCodeAt j]] : break nothing
			gnames.push unicodeGlyphs.[cldef.sequence.charCodeAt j].name

		interpretLookups gnames feature GSUB.lookups

		local g1 : new Glyph ('$clig.' + cldef.unicode)
		set g1.advanceWidth 0
		set g1.autoRefPriority 1
		set g1.unicode {cldef.unicode}
		foreach [gn : items-of gnames] : begin
			local g glyphs.(gn)
			g1.applyTransform : new Transform 1 0 0 1 (-g1.advanceWidth) 0
			g1.includeGlyph g
			g1.applyTransform : new Transform 1 0 0 1 (g1.advanceWidth) 0
			set g1.advanceWidth : g1.advanceWidth + g.advanceWidth

		set glyphs.(g1.name) g1
		set unicodeGlyphs.(cldef.unicode) g1
		glyphList.push g1
		set GDEF.glyphClassDef.(g1.name) GDEF_LIGATURE