1 files changed, 57 insertions, 1 deletions
diff --git a/src/gobang.go b/src/gobang.go
index 3c705b7..88b4c57 100644
--- a/src/gobang.go
+++ b/src/gobang.go
@@ -76,8 +76,64 @@ var (
 
 
 
+func countLeadingChar(s string, c byte) int {
+	n := 0
+	for {
+		if len(s) == n {
+			return n
+		}
+
+		if s[n] == c {
+			n++
+			continue
+		} else {
+			return n
+		}
+	}
+}
+
+func countLeadingTabs(s string) int {
+	return countLeadingChar(s, '\t')
+}
+
+func notEmptyString(s string) bool {
+	return len(s) > 0
+}
+
 func Heredoc(s string) string {
-	return strings.Trim(strings.ReplaceAll(s, "\t", ""), "\n") + "\n"
+	lines := strings.Split(s, "\n")
+	if lines[0] == "" {
+		lines = lines[1:]
+	}
+	length := len(lines)
+	if length > 0 && lines[length - 1] == "" {
+		lines = lines[:length - 1]
+	}
+	if len(lines) == 0 {
+		lines = append(lines, "")
+	}
+	last := lines[len(lines) - 1]
+	if len(last) > 0 && countLeadingTabs(last) == len(last) {
+		lines = lines[:len(lines) - 1]
+	}
+	if len(lines) == 0 {
+		lines = append(lines, "")
+	}
+
+	countableLines := Map(countLeadingTabs, Filter(notEmptyString, lines))
+	if len(countableLines) == 0 {
+		countableLines = append(countableLines, 0)
+	}
+	minIndentation := slices.Min(countableLines)
+	trimmedLines := Map(func(s string) string {
+		if len(s) == 0 {
+			return s
+		} else {
+			return s[minIndentation:]
+		}
+	}, lines)
+	return strings.Join(trimmedLines, "\n") + "\n"
+
 }
 
 func SetOf[T comparable](values ...T) SetT[T] {