#!/usr/bin/env js24
// Create a tune index from the abcm2ps PostScript output
// (javascript version with js24 - mozjs24)

// Copyright (C) 2017 Jean-François Moine <moinejf@free.fr>

// 2017-07-23
//	Bad output when index on many pages
//	Wrong computation of the number of indexes per page
//	Accept m$windows and MAC files
// 2017-04-14
//	Creation

var	before, main,
	args = scriptArgs

function do_index(fn) {
	var	i, j, index, a,
		page, atitle, title,
		titlelist, xmid, font, gsave, margin,
		x, ph, fh, lh, n, first,
		file = read(fn)

	if (!file) {
		printErr('Cannot read "' + fn + '"')
		quit()
	}

	// handle m$windows and MAC files
	if (file.indexOf('\r\n') >= 0)
		file = file.replace(/\r\n/g, '\n')
	if (file.indexOf('\r') >= 0)
		file = file.replace(/\r/g, '\n')
		
	i = file.indexOf('%%EndSetup\n');
	if (i < 0) {
		printErr('"' + fn + '" is not a PostScript file')
		quit()
	}
	i += 11;
	titlelist = []

	// loop on the lines
	while (1) {
		j = file.indexOf('\n', i)	// end of line
		if (j < 0)
			break
		if (file[i] == '%') {
			switch (file.slice(i, i + 8)) {
			case '%%Page: ':
				i += 8;
				page = file.slice(i, i + 5).match(/\d+/)
				if (gsave)
					break
				i = ++j;
				j = file.indexOf('\n', i);
				gsave = file.slice(i, j);
				break
			case '% --- wi':	// "% --- width <width>"
				if (xmid)
					break
				xmid = file.slice(i + 12, j - 1) * 0.5
				i = ++j;
				j = file.indexOf('\n', i);
				margin = file.slice(i, j);
				break
			case '% --- ti':	// "% --- title <title>"
						// "% --- titlesub <subtitle>"
				if (file.slice(i + 11, i + 14) == 'sub') {
					if (main)
						break
					atitle = file.slice(i + 15, j)
				} else {
					atitle = file.slice(i + 12, j)
				}
				i = ++j;
				j = file.indexOf('\n', i);
				title = file.slice(i, j);
				i = title.indexOf(']arrayshow')
				if (i > 0) {
					title = title.match(/\[.*\]/).toString();
					title = title.replace(/^\[\(\d+.  /, '[(');
					titlelist.push({
						a: atitle,
						b: title + '(' + page + ')mkidx2\n',
						p: page
						})
				} else {
					title = title.match(/\(.*\)/).toString();
					title = title.replace(/^\(\d+.  /, '(');
					titlelist.push({
						a: atitle,
						b: title + '(' + page + ')mkidx\n',
						p: page
						})
				}
				break
			case '% --- fo':	// "% --- font <size> <name>"
				if (font)
					break
				font = file.slice(i + 11, j)
				break
			}
		}
		i = ++j
	}

	// sort the titles
	titlelist = titlelist.sort(function (a, b) {
			if (a.a < b.a)
				return -1
			if (a.a > b.a)
				return 1
			return 0
		})

	// generate the index functions
	x = xmid * 2;			// page width
	fh = font.match(/\d+/) * 1.1;
	file = file.replace('%%EndSetup', "% for tune index\n\
/mklink{\n\
	[ /Rect [35 0 300 20] /Page 5 -1 roll /View [ /XYZ 0 830 null ]\n\
	/Border [0 0 0] /Subtype /Link /ANN pdfmark}!\n\
/mkidx{	" + (x - 40).toFixed(0) + " 0 M showr\n\
	40 0 M show 20 0 RM\n\
	{(  .  )show currentpoint pop " + (x - 80).toFixed(0) + " ge{exit}if}loop\n\
	0 -" + fh + " T}!\n\
/mkidx2{ " + (x - 40).toFixed(0) + " 0 M showr\n\
	40 0 M arrayshow 20 0 RM\n\
	{(  .  )show currentpoint pop " + (x - 80).toFixed(0) + " ge{exit}if}loop\n\
	0 -" + fh + " T}!\n\
%%EndSetup");

	// generate the index
	index = '% -- Tune index\n';
	a = gsave.split(/\s+/);
	ph = a[a.length - 2];		// page height
	lh = fh * 1.6;			// height of header lines
	n = (ph / fh - 4) | 0;
	first = true
	while (1) {
		page++;
		i = n;
		index += '%%Page: ' + page + ' ' + page + '\n' +
			gsave + '\n' +
			margin + '\n' +
			font + '\n\
0 -' + lh.toFixed(1) + ' T\n'
		if (first) {
			first = false;
			index += xmid.toFixed(0) + ' 0 M(index)showc\n\
0 -' + lh.toFixed(1) + ' T\n';
			i -= 2
		}
		while (--i >= 0) {
			a = titlelist.shift()
			if (!a)
				break
			index += a.p + ' mklink' + a.b
		}
		index += '%%PageTrailer\n\
grestore\n\
showpage\n\
%%EndPage: ' + page + ' ' + page + '\n'
		if (!a)
			break
	}

//should update %%Pages: <n>
	if (before)
		print(file.replace('%%EndSetup\n', '%%EndSetup\n' + index))
	else
		print(file.replace('%%Trailer', index + '%%Trailer'))
}

// main
	if (args[0] == '-b') {
		before = true;
		args.shift()
	}
	if (args[0] == '-m') {
		main = true;
		args.shift()
	}
	if (!args[0]) {
		printErr('Add a tune index to a abcm2ps output.\n\
Usage: ./abcmaddidx [options] <input abcm2ps file>\n\
  -b     set the index before the music\n\
  -m     set an index for main titles only (not for subtitles)\n\
The resulting file goes to stdout')
		quit()
	}
	do_index(args[0])