#!/bin/awk -f

# aux/emparse -- parse em source

function beginblock(name) {
	if (name == "nl") printf "<ol>\n"
	else printf "<%s>\n", name
}

function endblock(name) {
	if (name == "nl") printf "</ol>\n"
	else printf "</%s>\n", name
}

function newblock(name) {
	beginblock(name)
	openblock = name
	openitem = 0
	expectblock = 0
}

function breakblock() {
	if (openitem) {
		printf "</li>\n"
		while (itemlevel-- > 1)
			endblock(openblock)
		itemlevel = 1
	}
	if (opendef) printf "</dd>\n"
	if (openblock) endblock(openblock)
	openitem = 0
	opendef = 0
	openblock = 0
	expectblock = 1
}

function heading(level, line) {
	sub("^=* ", "", line)
	sub(" =*$", "", line)
	printf "<h%d>%s</h%d>\n", level, line, level
	# should inline formatting be supported in headings?
}

function item(level, type, line) {
	if (openitem) printf "</li>"
	openitem = 1
	if (level > itemlevel) printf "<ul>\n"
	if (level < itemlevel) printf "</ul>\n"
	itemlevel = level
	if (type == "ul") {
		sub("^ +- ", "")
		printf "<li>"
	}
	if (type == "ol") {
		match($0, "[0-9a-z]+\.")
		v = substr($0, RSTART, RLENGTH-1)
		sub("^ +[0-9a-z]+\. ", "")
		printf "<li value=\"%s\">", v
	}
	if (type == "nl") {
		match($0, "\\[[0-9a-z]+\\]")
		v = substr($0, RSTART+1, RLENGTH-2)
		sub("^ +\\[[0-9a-z]+\\] ", "")
		printf "<li value=\"%s\" id=\"ref%s\">", v, v
	}
}

function term(line, t) { # t is a local variable
	if (opendef) printf "</dd>"
	opendef = 1
	t = $0; d  = $0
	sub("^ ", "", t)
	sub(": .*$", "", t)
	sub("^ [^:]+: ", "")
	printf "<dt>%s</dt><dd>", t
}

function ref(v) {
	if (ENVIRON["ref" v] != "")
		return "(<a href=\"" ENVIRON["ref" v] "\">" linktext "</a>)"
	else
		return "[<a href=\"#ref" v "\">" v "</a>]"
}

function format(line) {
	n = split(line, w, "[ 	]")
	for (i = 0; i <= n; i++) {
		if (w[i] == "") continue;

		if (match(w[i], "^\\[[0-9a-z]+\\]$"))
			w[i] = ref(substr(w[i], 2, RLENGTH-2))
		else if (match(w[i], "^\[[0-9a-z]+\][.,:;?!]$"))
			w[i] = ref(substr(w[i], 2, RLENGTH-3)) substr(w[i], RLENGTH)

		if (match(w[i], "^`"))
			w[i] = "<tt>" substr(w[i], 2)
		else if (match(w[i], "^\\*"))
			w[i] = "<i>" substr(w[i], 2)
		else if (match(w[i], "^_"))
			w[i] = "<b>" substr(w[i], 2)

		if (match(w[i], "`$"))
			w[i] = substr(w[i], 1, RSTART-1) "</tt>"
		else if (match(w[i], "\\*$"))
			w[i] = substr(w[i], 1, RSTART-1) "</i>"
		else if (match(w[i], "_$"))
			w[i] = substr(w[i], 1, RSTART-1) "</b>"
		else if (match(w[i], "`[.,:;?!]$"))
			w[i] = substr(w[i], 1, RSTART-1) "</tt>" substr(w[i], RSTART+1)
		else if (match(w[i], "\\*\.$"))
			w[i] = substr(w[i], 1, RSTART-1) "</i>" substr(w[i], RSTART+1)
		else if (match(w[i], "_[.,:;?!]$"))
			w[i] = substr(w[i], 1, RSTART-1) "</b>" substr(w[i], RSTART+1)

		printf "%s", w[i]
		if (i < n) printf " "
	}
	printf "\n"
}

BEGIN {
	expectblock = 1
	itemlevel = 1
	linktext = ENVIRON["linktext"]
	if (!linktext) linktext = "link"
}
END { breakblock() }

/^$/							{ breakblock(); getline }
expectblock && /^  /			{ newblock("table") }
expectblock && /^ - /			{ newblock("ul") }
expectblock && /^ [0-9a-z]+\. /		{ newblock("ol") }
expectblock && /^ \[[0-9a-z]\]+ /	{ newblock("nl") }
expectblock && /^ .*: /			{ newblock("dl") }
expectblock && /^	/			{ newblock("pre"); sub("^	", "") }
expectblock && /^---$/			{ expectblock = 0; printf "<hr/>\n"; next }
expectblock && /^= .* =$/			{ heading(1, $0); next }
expectblock && /^== .* ==$/			{ heading(3, $0); next }
expectblock && /^=== .* ===$/		{ heading(3, $0); next }
expectblock && /^==== .* ====$/		{ heading(4, $0); next }
expectblock && /^===== .* =====$/	{ heading(5, $0); next }
expectblock && /^====== .* ======$/	{ heading(6, $0); next }
expectblock { newblock("p") }

block = "ul" && /^ - /				{ item(1, "ul", line) }
block = "ol" && /^ [0-9a-z]+\. /		{ item(1, "ol", line) }
block = "nl" && /^ \[[0-9a-z]\]+ [^ 	]+$/	{ next; }			# hyperlink reference
block = "nl" && /^ \[[0-9a-z]\]+ /		{ item(1, "nl", line) }	# text reference
block = "dl" && /^ .*: /				{ term(line) }

block = "ul" && /^  -/			{ item(2, "ul", line) }
block = "ol" && /^  [0-9a-z]+\./	{ item(2, "ol", line) }
block = "ul" && /^   -/			{ item(3, "ul", line) }
block = "ol" && /^   [0-9a-z]+\./	{ item(3, "ol", line) }
block = "ul" && /^    -/			{ item(4, "ul", line) }
block = "ol" && /^    [0-9a-z]+\./	{ item(4, "ol", line) }
block = "ul" && /^     -/			{ item(5, "ul", line) }
block = "ol" && /^     [0-9a-z]+\./	{ item(5, "ol", line) }
block = "ul" && /^      -/			{ item(6, "ul", line) }
block = "ol" && /^      [0-9a-z]+\./	{ item(6, "ol", line) }

block = "pre"  && /^	/	{ sub("^	", ""); printf "%s\n", $0; next }

{ format($0) }