--[[Mp3 id3 v2.3 tag reader APIC Extract/edit/insert - By WeBuLtR@

Changelog v0.9.0.0:
	- Added function id3.readAPICInfo: Returns available info of the APIC frame and can extract the APIC picture
	- Improved function id3.changeArt: Added PNG support (omits png's CRC), description and much more;
	- Fixed function id3.changeArt: Was deleting the mp3 data if a png image was found and removed unnecessary code
	- Fixed function id3.getArt: Was failing while extracting png files

NOTES:
	- This code won't work with unicode data for now
	- id3.getArt and id3.readAPICInfo functions extract the APIC picture file in different ways
]]--
id3 = {};
id3.version = "0.9.0.0";
function id3.getV1(mp3)
--Thnx to: http://psp.scenebeta.com/node/70241
	local name,artist,album,track,genre,year,comment = ""
	local tGenre = {};
	tGenre[0] = "Blues";
	tGenre[1] = "Classic Rock";
	tGenre[2] = "Country";
	tGenre[3] = "Dance";
	tGenre[4] = "Disco";
	tGenre[5] = "Funk";
	tGenre[6] = "Grunge";
	tGenre[7] = "Hip-Hop";
	tGenre[8] = "Jazz";
	tGenre[9] = "Metal";
	tGenre[10] = "New Age";
	tGenre[11] = "Oldies";
	tGenre[12] = "Other";
	tGenre[13] = "Pop";
	tGenre[14] = "R&B";
	tGenre[15] = "Rap";
	tGenre[16] = "Reggae";
	tGenre[17] = "Rock";
	tGenre[18] = "Techno";
	tGenre[19] = "Industrial";
	tGenre[20] = "Alternative";
	tGenre[21] = "Ska";
	tGenre[22] = "Death Metal";
	tGenre[23] = "Pranks";
	tGenre[24] = "Soundtrack";
	tGenre[25] = "Euro-Techno";
	tGenre[26] = "Ambient";
	tGenre[27] = "Trip-Hop";
	tGenre[28] = "Vocal";
	tGenre[29] = "Jazz+Funk";
	tGenre[30] = "Fusion";
	tGenre[31] = "Trance";
	tGenre[32] = "Classical";
	tGenre[33] = "Instrumental";
	tGenre[34] = "Acid";
	tGenre[35] = "House";
	tGenre[36] = "Game";
	tGenre[37] = "Sound Clip";
	tGenre[38] = "Gospel";
	tGenre[39] = "Noise";
	tGenre[40] = "Alternative Rock";
	tGenre[41] = "Bass";
	tGenre[43] = "Punk";
	tGenre[44] = "Space";
	tGenre[45] = "Meditative";
	tGenre[46] = "Instrumental Pop";
	tGenre[47] = "Instrumental Rock";
	tGenre[48] = "Ethnic";
	tGenre[49] = "Gothic";
	tGenre[50] = "Darkwave";
	tGenre[51] = "Techno-Industrial";
	tGenre[52] = "Electronic";
	tGenre[53] = "Pop-Folk";
	tGenre[54] = "Eurodance";
	tGenre[55] = "Dream";
	tGenre[56] = "Southern Rock";
	tGenre[57] = "Comedy";
	tGenre[58] = "Cult";
	tGenre[59] = "Gangsta";
	tGenre[60] = "Top 40";
	tGenre[61] = "Christian Rap";
	tGenre[62] = "Pop/Funk";
	tGenre[63] = "Jungle";
	tGenre[64] = "Native US";
	tGenre[65] = "Cabaret";
	tGenre[66] = "New Wave";
	tGenre[67] = "Psychadelic";
	tGenre[68] = "Rave";
	tGenre[69] = "Showtunes";
	tGenre[70] = "Trailer";
	tGenre[71] = "Lo-Fi";
	tGenre[72] = "Tribal";
	tGenre[73] = "Acid Punk";
	tGenre[74] = "Acid Jazz";
	tGenre[75] = "Polka";
	tGenre[76] = "Retro";
	tGenre[77] = "Musical";
	tGenre[78] = "Rock & Roll";
	tGenre[79] = "Hard Rock";
	tGenre[80] = "Folk";
	tGenre[81] = "Folk-Rock";
	tGenre[82] = "National Folk";
	tGenre[83] = "Swing";
	tGenre[84] = "Fast Fusion";
	tGenre[85] = "Bebob";
	tGenre[86] = "Latin";
	tGenre[87] = "Revival";
	tGenre[88] = "Celtic";
	tGenre[89] = "Bluegrass";
	tGenre[90] = "Avantgarde";
	tGenre[91] = "Gothic Rock";
	tGenre[92] = "Progressive Rock";
	tGenre[93] = "Psychedelic Rock";
	tGenre[94] = "Symphonic Rock";
	tGenre[95] = "Slow Rock";
	tGenre[96] = "Big Band";
	tGenre[97] = "Chorus";
	tGenre[98] = "Easy Listening";
	tGenre[99] = "Acoustic 100 - Humour";
	tGenre[101] = "Speech";
	tGenre[102] = "Chanson";
	tGenre[103] = "Opera";
	tGenre[104] = "Chamber Music";
	tGenre[105] = "Sonata";
	tGenre[106] = "Symphony";
	tGenre[107] = "Booty Bass";
	tGenre[108] = "Primus";
	tGenre[109] = "Porn Groove";
	tGenre[110] = "Satire";
	tGenre[111] = "Slow Jam";
	tGenre[112] = "Club";
	tGenre[113] = "Tango";
	tGenre[114] = "Samba";
	tGenre[115] = "Folklore";
	tGenre[116] = "Ballad";
	tGenre[117] = "Power Ballad";
	tGenre[118] = "Rhytmic Soul";
	tGenre[119] = "Freestyle";
	tGenre[120] = "Duet";
	tGenre[121] = "Punk Rock";
	tGenre[122] = "Drum Solo";
	tGenre[123] = "Acapella";
	tGenre[124] = "Euro-House";
	tGenre[125] = "Dance Hall";
	tGenre[126] = "Goa";
	tGenre[127] = "Drum & Bass";
	tGenre[128] = "Club-House";
	tGenre[129] = "Hardcore";
	tGenre[130] = "Terror";
	tGenre[131] = "Indie";
	tGenre[132] = "BritPop";
	tGenre[133] = "Negerpunk";
	tGenre[134] = "Polsk Punk";
	tGenre[135] = "Beat";
	tGenre[136] = "Christian Gangsta";
	tGenre[137] = "Heavy Metal";
	tGenre[138] = "Black Metal";
	tGenre[139] = "Crossover";
	tGenre[140] = "Contemporary C";
	tGenre[141] = "Christian Rock";
	tGenre[142] = "Merengue";
	tGenre[143] = "Salsa";
	tGenre[144] = "Thrash Metal";
	tGenre[145] = "Anime";
	tGenre[146] = "JPop";
	tGenre[147] = "SynthPop";
	tGenre[255] = "Not defined";
	local fbuf = io.open(mp3,"rb");
	if fbuf then
		fbuf:seek("end",-128);
		local tag = fbuf:read(3);
		if tag == "TAG" then
			fbuf:seek("end",-125);
			name = fbuf:read(30);
			fbuf:seek("end",-95);
			artist = fbuf:read(30);
			fbuf:seek("end",-65);
			album = fbuf:read(30);
			fbuf:seek("end",-35);
			year = fbuf:read(4);
			fbuf:seek("end",-31);
			comment = fbuf:read(28);
			fbuf:seek("end",-2);
			track = string.byte(fbuf:read(1));
			fbuf:seek("end",-1);
			genre = tGenre[string.byte(fbuf:read(1))];
			for i = 1, string.len(name) do
				if string.byte(string.sub(name,-1)) == 0 or string.byte(string.sub(name,-1)) == 32 then
					name = string.sub(name,1,-2);
				end
			end
			for i = 1, string.len(artist) do
				if string.byte(string.sub(artist,-1)) == 0 or string.byte(string.sub(artist,-1)) == 32 then
					artist = string.sub(artist,1,-2);
				end
			end
			for i = 1, string.len(album) do
				if string.byte(string.sub(album,-1)) == 0 or string.byte(string.sub(album,-1)) == 32 then
					album = string.sub(album,1,-2);
				end
			end
		end
		fbuf:close();
		return { name = name, artist = artist, album = album, track = track, genre = genre, year = year, comment = comment };
	else
		return nil;
	end
end

function id3.getV2(mp3,tag)
--Thnx to: http://psp.scenebeta.com/node/70241
	local fbuf = io.open(mp3,"rb")
	local ttag = ""
	if fbuf then
		fbuf:seek("set")
		local fdata = fbuf:read(100000)
		fbuf:close()
	end
	if fdata then
		local fndid = string.find(fdata, tag)
	end
	if fndid then
		ttag = string.sub(fdata, fndid + 11, fndid + 9 + string.byte(string.sub(fdata, fndid+7, fndid+7)))
		ttag = string.gsub(ttag, "\0", "")
	end
	return ttag
end

function id3.getArt(mp3, dest_file)
--Thnx to: http://psp.scenebeta.com/node/70241
	local fbuf = io.open(mp3,"rb");
	if fbuf then
		fbuf:seek("set");
		local fdata = fbuf:read("*a");
		local fndid = string.find(fdata, "APIC");
		if fndid then
			local beg = string.sub(fdata,fndid);
			if string.find(beg, "JFIF") then
				local beg_pos = string.find(beg, "JFIF")-6;
				beg = string.sub(beg,beg_pos)
				local fin = string.find(beg, string.char(255)..string.char(217));
				if fin then
					fin = fin + 1;
					img = string.sub(beg,1,fin);
					fbuf:close()
					local file = io.open(dest_file..".jpg","wb");
					file:write(img);
					file:close();
					return true;
				else
					return nil, "JPG data not found";
				end
			else
				local beg_pos = string.find(beg, "‰PNG")
				if beg_pos then
					beg = string.sub(beg,beg_pos);
					local fin = string.find(beg, "IEND")+7;
					img = string.sub(beg,1,fin);
					fbuf:close();
					local file = io.open(dest_file..".png","wb");
					file:write(img);
					file:close();
					return true;
				else
					return nil, "File format not found";
				end
			end
		else
			return nil, "Couldn't find album art image";
		end
	else
		return nil, "Couldn't open mp3 file";
	end
end

function id3.changeArt(mp3, newIMG, desc)
--[[Insert or replace an APIC header
boolean id3.changeArt(string MP3File, string ImageFileToInsert, string ImageDescription);
Thnx to: MEEEEE (WeBuLtR@) lol]]--
	local sImg = (type(newIMG) == "string") and newIMG or "";
	local _,_,mime = sImg:find("%.+(.+)")
	if not mime then
		return nil, "Invalid IMG";
	else
		mime = mime:lower();
		if mime ~= "jpg" and mime ~= "png" and mime ~= "jpeg" then
			return nil, "Image must be png or jpg";
		elseif mime == "jpg" then
			mime = "jpeg";
		end
	end
	local sF = io.open(mp3, "rb");
	if sF then
		local data = sF:read("*a");
		sF:close();
		if data:sub(1,3) == "ID3" then
			local tag_size = data:sub(7,10);
			local n = "";
			for x in tag_size:gmatch(".") do
				local tmp = id3.Hex2Bin(string.format("%02X", x:byte()));
				n = n..tmp:sub(2);
			end
			local d = string.format("%032s", n);
			local size = tonumber("0x"..id3.Bin2Hex(d))+10;
			local id3_data = data:sub(1, size);
			local apic = string.find(id3_data, "APIC");
			local img = io.open(newIMG, "rb");
			if not img then
				return nil, "New ART image not found";
			end
			local head_data = string.sub(id3_data, 1, 6);

			--APIC Frame
			local text_encoding = string.char(0);
			local mime_type = "image/"..mime..string.char(0);
			local pic_type = string.char(3);--Default: Front cover
			local description = (type(desc)=="string") and desc:sub(1,63)..string.char(0) or string.char(0);
			local img_data = img:read("*a");

			--Check png format
			if mime == "png" then
				if img_data:find("IEND") then
					local s,_,v = img_data:find("IEND(.+)");
					if not v then
						return nil, "Invalid PNG file";
					elseif #v > 4 then
						img_data = img_data:sub(1, s+7);
					elseif #v < 4 then
						return nil, "Invalid PNG file, must end with 4 bytes after the IEND chunk";
					end
				end
			end

			--APIC Header
			local apic_head = "APIC";
			local img_size = string.format("%08X", #text_encoding + #mime_type + #pic_type + #description + #img_data);
			local img_sdata = "";
			for s in string.gmatch(img_size , "..") do
				img_sdata = img_sdata..string.char(tonumber("0x"..s));
			end
			local apic_flag = string.char(0,0);
			img:close();

			--APIC complete tag
			local apic_data = apic_head..img_sdata..apic_flag..text_encoding..mime_type..pic_type..description..img_data;
			if apic then
				local fin = string.find(id3_data, string.char(255)..string.char(217));
				if fin then
					fin = fin+1;
				elseif string.find(id3_tag, "IEND") then
					fin = string.find(id3_data, "IEND")+7;
				else
					return nil, "Invalid APIC TAG";
				end
				local prev_data = string.sub(id3_data, 11, apic-1);
				local post_data = string.sub(id3_data, fin+1);
				local new_adata = prev_data..apic_data..post_data;
				local new_size = id3.IntToSynchSafe(#new_adata);
				local  sO = io.open(mp3, "wb");
				if sO then
					sO:write(head_data..new_size..new_adata..string.sub(data, size+1));
					sO:close();
					return true, "APIC edited";
				else
					return nil, "Couldn't reopen file";
				end
			else
				local post_data = string.sub(id3_data, 11);
				local new_adata = apic_data..post_data;
				local new_size = id3.IntToSynchSafe(#new_adata);
				local  sO = io.open(mp3, "wb");
				if sO then
					sO:write(head_data..new_size..new_adata..string.sub(data, size+1));
					sO:close();
					return true, "APIC inserted";
				else
					return nil, "Couldn't reopen file";
				end
			end
		else
			return nil, "ID3 v2 TAG not found";
		end
	end
end

function id3.getID3v23Size(mp3file)
--[[Returns the ID3 v23 TAG Size
More info: http://www.id3.org/id3v2.3.0]]--
	local sF = io.open(mp3file, "rb");
	if sF then
		local data = sF:read(10);
		sF:close();
		if data:sub(1,3) == "ID3" then
			local tag_size = data:sub(7,10);
			local n = "";
			for x in tag_size:gmatch(".") do
				local tmp = id3.Hex2Bin(string.format("%02X", x:byte()));
				n = n..tmp:sub(2);
			end
			local d = string.format("%032s", n);
			return tonumber("0x"..id3.Bin2Hex(d))+10;
		else
			return nil, "ID3 v2 TAG not found";
		end
	else
		return nil, "File not found";
	end
end

function id3.IntToSynchSafe(integer)
--[[Returns the integer converted into a SynchSafe (4 bytes) string + the new integer value (just to check) + the hex value;
More info: http://en.wikipedia.org/wiki/Synchsafe]]--
	assert(type(integer)=="number", "Value must be a number");
	local hex = string.format("%08x",integer);
	local nhex = id3.Hex2Bin(hex);
	local t,i = {},4;
	for x in string.gmatch(nhex, "........") do
		t[i] = x;
		i = i-1;
	end
	local newbin, sres, nt= "", "", {};
	for x, y in pairs(t) do
		local a, c = y:sub(1,x), y:sub(x+1);
		table.insert(nt, a);
		newbin = "0"..c..(nt[x-1] or "")..newbin;
	end
	local newhex = id3.Bin2Hex(newbin);
	for sss in string.gmatch(newhex, "..") do
		sres = sres..string.char(tonumber("0x"..sss));
	end
	return sres, tonumber("0x"..newhex), "0x"..newhex;
end

function id3.Hex2Bin(s)
--[[Thanks to Diaelectronics for the hex2bin and bin2hex functions
More functions and module: http://www.dialectronics.com/Lua/code/BinDecHex.shtml]]--
	local hex2bin = {
		["0"] = "0000",
		["1"] = "0001",
		["2"] = "0010",
		["3"] = "0011",
		["4"] = "0100",
		["5"] = "0101",
		["6"] = "0110",
		["7"] = "0111",
		["8"] = "1000",
		["9"] = "1001",
		["a"] = "1010",
		["b"] = "1011",
		["c"] = "1100",
		["d"] = "1101",
		["e"] = "1110",
		["f"] = "1111"
	};
	local ret = ""
	local i = 0
	for i in string.gfind(s, ".") do
		i = string.lower(i)
		ret = ret..hex2bin[i]
	end
	return ret
end

function id3.Bin2Hex(s)
	local bin2hex = {
		["0000"] = "0",
		["0001"] = "1",
		["0010"] = "2",
		["0011"] = "3",
		["0100"] = "4",
		["0101"] = "5",
		["0110"] = "6",
		["0111"] = "7",
		["1000"] = "8",
		["1001"] = "9",
		["1010"] = "A",
		["1011"] = "B",
		["1100"] = "C",
		["1101"] = "D",
		["1110"] = "E",
		["1111"] = "F"
	};
	local l = 0
	local h = ""
	local b = ""
	local rem
	l = string.len(s)
	rem = l % 4
	l = l-1
	h = ""
	if (rem > 0) then
		s = string.rep("0", 4 - rem)..s
	end
	for i = 1, l, 4 do
		b = string.sub(s, i, i+3);
		h = h..bin2hex[b];
	end
	return h;
end
function id3.readAPICInfo(mp3, writeAPIC)
--[[Reads the available info of the APIC frame
table id3.readAPICInfo(string MP3File, boolean WriteImageFileToTempFile);
Thnx to MEEEEE (WeBuLtR@) lol]]--
	local tTypes = {};
	tTypes[0] = "Other"
	tTypes[1] = "Icon";--32x32px file icon (PNG only)
	tTypes[2] = "Other icon file";
	tTypes[3] = "Front cover";
	tTypes[4] = "Back conver";
	tTypes[5] = "Leaflet";
	tTypes[6] = "Media";
	tTypes[7] = "Lead artist";
	tTypes[8] = "Artist";
	tTypes[9] = "Conductor";
	tTypes[10] = "Band";
	tTypes[11] = "Composer";
	tTypes[12] = "Lyricist";
	tTypes[13] = "Recording location";
	tTypes[14] = "During recording";
	tTypes[15] = "During performance";
	tTypes[16] = "Video capture";
	tTypes[17] = "Bright colored fish";
	tTypes[18] = "Illustration";
	tTypes[19] = "Band logotype";
	tTypes[20] = "Publisher logotype";
	local wa = (type(writeAPIC)=="boolean") and writeAPIC or false;
	local sF = io.open(mp3, "rb");
	if sF then
		local sData = sF:read("*a");
		sF:close();
		if sData then
			--APIC HEADER
			local start = sData:find("APIC");
			if start then
				local sized = sData:sub(start+4, start+7);
				local size = "";
				for x in sized:gmatch(".") do
					size = size..string.format("%X", x:byte());
				end
				size = tonumber("0x"..size);
				local flags = sData:sub(start+8, start+9);

				--APIC FRAME
				local text_encoding = sData:sub(start+10, start+10);
				local mimee = sData:find("%z", start+11);
				local mime = sData:sub(start+11, mimee-1);
				local pic_type = string.byte(sData:sub(mimee+1, mimee+1));
				local desc_end = sData:find("%z", mimee+2);
				local description = sData:sub(mimee+2, desc_end-1);
				description = (#description == 0) and "" or description
				local pic_data = sData:sub(desc_end+1, desc_end+1+(size-(1+#mime+1+1+#description+2)));
				if wa then
					local f = io.open("temp."..mime, "wb");
					if f then
						f:write(pic_data);
						f:close();
					end
				end
				return {APICFrameSize = size, ImageSize=#pic_data, MimeType=mime, PictureType=tTypes[pic_type], description=description};
			else
				return nil, "APIC header not found";
			end
		end
	end
end