feat(ini): dependency-free INI reader for config and calendar data

1 files changed, 75 insertions, 0 deletions

diff --git a/internal/ini/ini.go b/internal/ini/ini.go
new file mode 100644
index 0000000..b4fc955
--- /dev/null
+++ b/internal/ini/ini.go
@@ -0,0 +1,75 @@
+// Package ini is a tiny dependency-free reader for the boring INI files lectio
+// uses for config and calendar data: [sections] (including "a/b" subsections),
+// "key = value" pairs (keys may be dotted, e.g. name.pl), and "#"/";" comments.
+// It preserves order and never interprets values beyond trimming.
+package ini
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"strings"
+)
+
+type Pair struct{ Key, Val string }
+
+type Section struct {
+	Name  string
+	Pairs []Pair
+}
+
+// Parse reads INI bytes into ordered sections. Pairs before the first [section]
+// go into a leading section with an empty Name.
+func Parse(data []byte) ([]Section, error) {
+	secs := []Section{{Name: ""}}
+	sc := bufio.NewScanner(bytes.NewReader(data))
+	sc.Buffer(make([]byte, 0, 64*1024), 1024*1024)
+	line := 0
+	for sc.Scan() {
+		line++
+		raw := stripComment(sc.Text())
+		s := strings.TrimSpace(raw)
+		if s == "" {
+			continue
+		}
+		if strings.HasPrefix(s, "[") {
+			if !strings.HasSuffix(s, "]") {
+				return nil, fmt.Errorf("ini: line %d: unclosed section header %q", line, s)
+			}
+			name := strings.TrimSpace(s[1 : len(s)-1])
+			secs = append(secs, Section{Name: name})
+			continue
+		}
+		eq := strings.IndexByte(s, '=')
+		if eq < 0 {
+			return nil, fmt.Errorf("ini: line %d: expected key = value, got %q", line, s)
+		}
+		key := strings.TrimSpace(s[:eq])
+		val := strings.TrimSpace(s[eq+1:])
+		cur := &secs[len(secs)-1]
+		cur.Pairs = append(cur.Pairs, Pair{key, val})
+	}
+	return secs, sc.Err()
+}
+
+// stripComment removes a trailing "#" or ";" comment (our values never contain
+// an unescaped # or ;).
+func stripComment(line string) string {
+	for i := 0; i < len(line); i++ {
+		if line[i] == '#' || line[i] == ';' {
+			return line[:i]
+		}
+	}
+	return line
+}
+
+// List splits a comma-separated value, trimming spaces and dropping empties.
+func List(val string) []string {
+	var out []string
+	for _, p := range strings.Split(val, ",") {
+		if t := strings.TrimSpace(p); t != "" {
+			out = append(out, t)
+		}
+	}
+	return out
+}