feat(clectio-gen): apply a calendar layer/sanctorale when generating

Add opt-in flags so clectio's tables can be regenerated from a customized
calendar instead of only the embedded universal one:

  clectio-gen -caldir DIR -use a,b [-sanctorale DIR] <new|old> y0 y1 out/

- -caldir + -use stack calendar layers (rank, colour, name, reading.*) over the
  calendar; -sanctorale DIR applies a full of.ini/ef.ini replacement.
- The BOOK table stays hermetic (LECTIO_CONFIG still points nowhere), so the
  generator can't read a stale user books.ini -- calendar customization and the
  book aliases are kept separate concerns.
- config.SetCalendarsDir lets CalendarsDir be pointed at an explicit layer dir
  without a full config tree (and without an unrelated books.ini there).

Verified end to end: a layer adding a feast with a proper gospel regenerates
into liturgy_of.h + verses_of.keys, and the rebuilt clectio shows it. Default
(no flags) output is byte-identical to before. make test green.

1 files changed, 40 insertions, 11 deletions

diff --git a/cmd/clectio-gen/main.go b/cmd/clectio-gen/main.go
index 9a2930d..422cd34 100644
--- a/cmd/clectio-gen/main.go
+++ b/cmd/clectio-gen/main.go
@@ -12,11 +12,18 @@
 // So the hard liturgical logic stays here (Go, oracle-validated); the C side is
 // a dumb lookup + renderer, and swapping the Bible never touches this generator.
 //
-// Usage: clectio-gen <new|old> <startYear> <endYear> <outdir>
+// Usage: clectio-gen [-caldir DIR -use NAMES] [-sanctorale DIR] <new|old> <startYear> <endYear> <outdir>
+//
+// By default it uses lectio's embedded, oracle-validated calendar. To bake a
+// customized calendar into clectio, point it at calendar layers (-caldir with a
+// comma-separated -use list) and/or a replacement sanctorale (-sanctorale DIR
+// with of.ini/ef.ini). Only the calendar is taken from those; the book table
+// stays embedded, so the generator never reads a stale user books.ini.
 package main
 
 import (
 	"bufio"
+	"flag"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -25,6 +32,7 @@ import (
 	"time"
 
 	"github.com/lukaszkasprzak/lectio/internal/bible"
+	"github.com/lukaszkasprzak/lectio/internal/caldata"
 	"github.com/lukaszkasprzak/lectio/internal/config"
 	"github.com/lukaszkasprzak/lectio/internal/liturgy"
 	"github.com/lukaszkasprzak/lectio/internal/readings"
@@ -92,30 +100,51 @@ type day struct {
 }
 
 func main() {
-	if len(os.Args) != 5 {
-		fmt.Fprintln(os.Stderr, "usage: clectio-gen <new|old> <startYear> <endYear> <outdir>")
+	caldir := flag.String("caldir", "", "directory of calendar-layer .ini files to apply (use with -use)")
+	use := flag.String("use", "", "comma-separated layer names to stack over the calendar (needs -caldir)")
+	sanctorale := flag.String("sanctorale", "", "directory with of.ini/ef.ini that REPLACE the embedded sanctorale")
+	flag.Usage = func() {
+		fmt.Fprintln(os.Stderr, "usage: clectio-gen [-caldir DIR -use NAMES] [-sanctorale DIR] <new|old> <startYear> <endYear> <outdir>")
+		flag.PrintDefaults()
+	}
+	flag.Parse()
+	args := flag.Args()
+	if len(args) != 4 {
+		flag.Usage()
 		os.Exit(2)
 	}
-	// Hermetic: point config at a nonexistent path so the generator always uses
-	// lectio's EMBEDDED calendar, lectionary and book table -- never the running
-	// user's ~/.config/lectio (whose books.ini/calendars/etc. could be stale and
-	// would silently change or drop readings).
+	// Hermetic BOOK table: point config at a nonexistent path so the generator
+	// never reads the running user's ~/.config/lectio/books.ini (which could be
+	// stale and silently drop readings). Calendar customization comes ONLY from
+	// the explicit flags below, so the two concerns stay separate.
 	os.Setenv("LECTIO_CONFIG", filepath.Join(os.TempDir(), "clectio-gen-no-such-dir", "config.ini"))
-	form := os.Args[1] // "new" (OF) or "old" (EF)
+	if *caldir != "" {
+		config.SetCalendarsDir(*caldir)
+	}
+	if *sanctorale != "" {
+		caldata.SetSanctoraleDir(*sanctorale)
+	}
+	var useList []string
+	if *use != "" {
+		useList = strings.Split(*use, ",")
+	}
+
+	form := args[0] // "new" (OF) or "old" (EF)
 	lect := "new"
 	tag := "of"
 	if form == "old" {
 		lect, tag = "traditional", "ef"
 	}
-	y0, _ := strconv.Atoi(os.Args[2])
-	y1, _ := strconv.Atoi(os.Args[3])
-	outdir := os.Args[4]
+	y0, _ := strconv.Atoi(args[1])
+	y1, _ := strconv.Atoi(args[2])
+	outdir := args[3]
 
 	base := func(sigla string) config.Config {
 		c := config.Default()
 		c.UILanguage = "en"
 		c.Lectionary = lect
 		c.SiglaStyle = sigla
+		c.Use = useList
 		return c
 	}
 	cfgEN, cfgLA := base("english"), base("latin")