all: fix custom IDs on first section got replaced

Any custom ID on the first section always replaced with the subsection
because, first, when detecting preamble we did not check for line with
kind ID "[[...]]" an short ID "[#...]".
Second, when parsing preamble we did not stop when we found line kind
ID and short ID.

This preamble thing is kind of annoying.
We need to revisit again how to detect preamble, maybe not calling
separate block parser, but making it linear as the default first child of
parent element.

4 files changed, 99 insertions, 24 deletions

diff --git a/asciidoctor_test.go b/asciidoctor_test.go
index 8944165..886e84c 100644
--- a/asciidoctor_test.go
+++ b/asciidoctor_test.go
@@ -20,11 +20,13 @@ func TestData(t *testing.T) {
 	var (
 		listTData    []*test.Data
 		tdata        *test.Data
-		inputCall    string
+		bbuf         bytes.Buffer
 		outputCall   string
 		inputName    string
 		subtestName  string
 		inputContent []byte
+		exp          []byte
+		got          []byte
 		err          error
 	)
 
@@ -34,28 +36,15 @@ func TestData(t *testing.T) {
 	}
 
 	for _, tdata = range listTData {
-		inputCall = tdata.Flag[`input_call`]
 		outputCall = tdata.Flag[`output_call`]
 
 		for inputName, inputContent = range tdata.Input {
 			subtestName = tdata.Name + `/` + inputName
 
 			t.Run(subtestName, func(t *testing.T) {
-				var (
-					doc  *Document
-					bbuf bytes.Buffer
-					exp  []byte
-					got  []byte
-				)
-
-				exp = tdata.Output[inputName]
-
 				bbuf.Reset()
 
-				switch inputCall {
-				default:
-					doc = Parse(inputContent)
-				}
+				var doc = Parse(inputContent)
 
 				switch outputCall {
 				case outputCallHTMLWriteHeader:
@@ -73,6 +62,7 @@ func TestData(t *testing.T) {
 					got = bbuf.Bytes()
 				}
 
+				exp = tdata.Output[inputName]
 				test.Assert(t, subtestName, string(exp), string(got))
 			})
 		}
diff --git a/document_parser.go b/document_parser.go
index d165ff9..27f92be 100644
--- a/document_parser.go
+++ b/document_parser.go
@@ -61,6 +61,8 @@ func parseSub(parentDoc *Document, content []byte) (subdoc *Document) {
 	return subdoc
 }
 
+// consumeLinesUntil given an element el, consume all lines until we found
+// a line with kind match with term or match with one in terms.
 func (docp *documentParser) consumeLinesUntil(el *element, term int, terms []int) (line []byte) {
 	var (
 		logp = `consumeLinesUntil`
@@ -148,7 +150,9 @@ func (docp *documentParser) hasPreamble() bool {
 		kind, _, _ = whatKindOfLine(line)
 		if kind == elKindSectionL1 || kind == elKindSectionL2 ||
 			kind == elKindSectionL3 || kind == elKindSectionL4 ||
-			kind == elKindSectionL5 {
+			kind == elKindSectionL5 ||
+			kind == lineKindID ||
+			kind == lineKindIDShort {
 			return notEmtpy > 0
 		}
 		notEmtpy++
@@ -276,9 +280,7 @@ func (docp *documentParser) parseMultiline(out io.Writer) {
 func (docp *documentParser) parseBlock(parent *element, term int) {
 	var (
 		logp = `parseBlock`
-		el   = &element{
-			kind: elKindUnknown,
-		}
+		el   = &element{}
 
 		line   []byte
 		isTerm bool
@@ -314,13 +316,19 @@ func (docp *documentParser) parseBlock(parent *element, term int) {
 			continue
 
 		case lineKindID:
+			if parent.kind == elKindPreamble {
+				docp.kind = lineKindEmpty
+				docp.prevKind = lineKindEmpty
+				docp.lineNum--
+				isTerm = true
+				continue
+			}
 			var (
 				idLabel   = line[2 : len(line)-2]
 				id, label = parseIDLabel(idLabel)
 			)
 			if len(id) > 0 {
-				el.ID = docp.doc.registerAnchor(
-					string(id), string(label))
+				el.ID = docp.doc.registerAnchor(string(id), string(label))
 				line = nil
 				continue
 			}
@@ -330,6 +338,14 @@ func (docp *documentParser) parseBlock(parent *element, term int) {
 			continue
 
 		case lineKindIDShort:
+			if parent.kind == elKindPreamble {
+				docp.kind = lineKindEmpty
+				docp.prevKind = lineKindEmpty
+				docp.lineNum--
+				isTerm = true
+				continue
+			}
+
 			var (
 				id    = line[2 : len(line)-1]
 				label []byte
@@ -338,8 +354,7 @@ func (docp *documentParser) parseBlock(parent *element, term int) {
 			id, label = parseIDLabel(id)
 
 			if len(id) > 0 {
-				el.ID = docp.doc.registerAnchor(
-					string(id), string(label))
+				el.ID = docp.doc.registerAnchor(string(id), string(label))
 				line = nil
 				continue
 			}
diff --git a/parser.go b/parser.go
index a748bde..6d47d1d 100644
--- a/parser.go
+++ b/parser.go
@@ -665,7 +665,7 @@ func parseClosedBracket(input []byte, openb, closedb byte) (out []byte, idx int)
 	return nil, -1
 }
 
-// parseIDLabel parse the string "ID (,LABEL)" into ID and label.
+// parseIDLabel parse the string "ID (,LABEL)" into id and label.
 // It will return empty id and label if ID is not valid.
 func parseIDLabel(s []byte) (id, label []byte) {
 	var idLabel = bytes.Split(s, []byte(`,`))
diff --git a/testdata/custom_ids_test.txt b/testdata/custom_ids_test.txt
new file mode 100644
index 0000000..917a492
--- /dev/null
+++ b/testdata/custom_ids_test.txt
@@ -0,0 +1,70 @@
+output_call: ToHTMLBody
+
+>>> without_preamble
+= Without preamble
+
+[#foo_v1_1_0]
+== foo v1.1.0 (2023-02-01)
+
+[#foo_v1_0_0]
+== foo v1.0.0 (2023-01-01)
+
+<<< without_preamble
+<div id="header">
+<h1>Without preamble</h1>
+</div>
+<div id="content">
+<div class="sect1">
+<h2 id="foo_v1_1_0">foo v1.1.0 (2023-02-01)</h2>
+<div class="sectionbody">
+</div>
+</div>
+<div class="sect1">
+<h2 id="foo_v1_0_0">foo v1.0.0 (2023-01-01)</h2>
+<div class="sectionbody">
+</div>
+</div>
+</div>
+<div id="footer">
+<div id="footer-text">
+</div>
+</div>
+
+>>> with_preamble
+= With preamble
+
+This is a preamble.
+
+[#foo_v1_1_0]
+== foo v1.1.0 (2023-02-01)
+
+[#foo_v1_0_0]
+== foo v1.0.0 (2023-01-01)
+
+<<< with_preamble
+<div id="header">
+<h1>With preamble</h1>
+</div>
+<div id="content">
+<div id="preamble">
+<div class="sectionbody">
+<div class="paragraph">
+<p>This is a preamble.</p>
+</div>
+</div>
+</div>
+<div class="sect1">
+<h2 id="foo_v1_1_0">foo v1.1.0 (2023-02-01)</h2>
+<div class="sectionbody">
+</div>
+</div>
+<div class="sect1">
+<h2 id="foo_v1_0_0">foo v1.0.0 (2023-01-01)</h2>
+<div class="sectionbody">
+</div>
+</div>
+</div>
+<div id="footer">
+<div id="footer-text">
+</div>
+</div>