feat(cli): EF ferial readings — weekdays repeat the preceding Sunday's Mass

dayReadings() falls back, for an EF weekday with no proper Mass, to the
preceding Sunday's temporal lectionary (the 1962 green-season rule). Lenten/
Advent proper ferias show the Sunday's readings pending their own data.

1 files changed, 26 insertions, 11 deletions

diff --git a/internal/cli/liturgy.go b/internal/cli/liturgy.go
index 975917a..af58a34 100644
--- a/internal/cli/liturgy.go
+++ b/internal/cli/liturgy.go
@@ -32,10 +32,34 @@ func runLiturgy(cfg config.Config, date string, stdout, stderr io.Writer) int {
 	}
 	day := calendar.Compute(d.UTC(), cfg.Selection(), layers)
 	tbl, _ := bible.LoadBookTable(userBooksINI())
-	printLiturgicalDay(stdout, cfg, tbl, day)
+	readings := dayReadings(cfg.Selection(), layers, d.UTC(), day)
+	printLiturgicalDay(stdout, cfg, tbl, day, readings)
 	return 0
 }
 
+// dayReadings resolves the day's Mass readings: the observed celebration's
+// inline propers, else the temporal lectionary for its slug, else -- for an EF
+// weekday with no proper Mass -- the preceding Sunday's Mass (the 1962 rule
+// that green-season ferias repeat the Sunday).
+func dayReadings(sel calendar.Selection, layers []calendar.Layer, date time.Time, day calendar.LiturgicalDay) []calendar.Reading {
+	var rs []calendar.Reading
+	for _, m := range day.Observed.Masses {
+		rs = append(rs, m.Readings...)
+	}
+	if len(rs) > 0 {
+		return rs
+	}
+	if r := caldata.TemporalReadings(sel.Form, day.Observed.Slug); len(r) > 0 {
+		return r
+	}
+	if sel.Form == "old" && day.Observed.Layer == "temporal" && date.Weekday() != time.Sunday {
+		sun := date.AddDate(0, 0, -int(date.Weekday())) // preceding Sunday (Sunday = 0)
+		sd := calendar.Compute(sun, sel, layers)
+		return caldata.TemporalReadings(sel.Form, sd.Observed.Slug)
+	}
+	return nil
+}
+
 // vernacularVersion is the offline corpus used to render reading text: Wujek
 // for Polish, Douay-Rheims otherwise (bt is scraped, so it is not used here).
 func vernacularVersion(cfg config.Config) string {
@@ -64,7 +88,7 @@ func readingLine(tbl *bible.BookTable, cfg config.Config, version, citation stri
 	return display, strings.Join(parts, " ")
 }
 
-func printLiturgicalDay(out io.Writer, cfg config.Config, tbl *bible.BookTable, day calendar.LiturgicalDay) {
+func printLiturgicalDay(out io.Writer, cfg config.Config, tbl *bible.BookTable, day calendar.LiturgicalDay, readings []calendar.Reading) {
 	fmt.Fprintf(out, "%s  %s\n", day.Date.Format("2006-01-02"), day.Weekday.String())
 	if day.SundayCycle != "" { // OF carries the reading cycles; EF does not
 		fmt.Fprintf(out, "season:   %s (week %d · Sunday cycle %s · weekday cycle %s)\n",
@@ -78,15 +102,6 @@ func printLiturgicalDay(out io.Writer, cfg config.Config, tbl *bible.BookTable,
 			fmt.Fprintf(out, "  also:   %s  [%s]\n", n, rankLabel(o.Rank))
 		}
 	}
-	// Readings: the observed celebration's inline propers, else the temporal
-	// lectionary for the day (proper-of-feast overrides the temporal cycle).
-	var readings []calendar.Reading
-	for _, m := range day.Observed.Masses {
-		readings = append(readings, m.Readings...)
-	}
-	if len(readings) == 0 {
-		readings = caldata.TemporalReadings(cfg.Selection().Form, day.Observed.Slug)
-	}
 	vern := vernacularVersion(cfg)
 	for _, r := range readings {
 		disp, txt := readingLine(tbl, cfg, vern, r.Citation)