mobile: add Days, a text-free week projection for the calendar

A week through Days benchmarks at ~9-10ms/op, versus ~23ms for seven
full days through Day.

1 files changed, 72 insertions, 0 deletions

diff --git a/mobile/mobile.go b/mobile/mobile.go
index 6312ee0..e79e748 100644
--- a/mobile/mobile.go
+++ b/mobile/mobile.go
@@ -14,6 +14,7 @@ package mobile
 import (
 	"encoding/json"
 	"strings"
+	"time"
 
 	"github.com/lukaszkasprzak/lectio/internal/config"
 	"github.com/lukaszkasprzak/lectio/internal/i18n"
@@ -112,6 +113,77 @@ func Day(date, form, version, lang string) string {
 	return string(b)
 }
 
+// summaryPart is one section of a day, citation only -- no rendered text.
+type summaryPart struct {
+	Part     string `json:"part"`
+	Citation string `json:"citation"`
+}
+
+// daySummary is one day's identity and its reading citations. It is Day's
+// cheaper projection: the calendar view needs the day's shape, not its text.
+type daySummary struct {
+	Date      string        `json:"date"`
+	Name      string        `json:"name"`
+	Rank      string        `json:"rank"`
+	RankLabel string        `json:"rank_label"`
+	Colour    string        `json:"colour"`
+	Parts     []summaryPart `json:"parts"`
+	Error     string        `json:"error,omitempty"`
+}
+
+// Days returns count consecutive days from start as a JSON array, each with its
+// identity and reading citations but no reading text. It is the calendar view's
+// source.
+//
+//	start - "YYYY-MM-DD", taken literally: aligning to a week is the caller's job
+//	count - 1..366; anything else yields "[]"
+//	form  - "of" or "ef"
+//	lang  - interface language for the name, rank word and citation dialect
+//
+// No version parameter: the corpus decides only scripture text, which this never
+// renders, while the citation's sigla dialect follows lang.
+//
+// A day that fails to compute carries its own "error" and does not abort the
+// rest, so one bad date cannot blank a whole week. Malformed input yields "[]"
+// rather than an error string, so the caller always parses an array.
+func Days(start string, count int, form, lang string) string {
+	if count < 1 || count > 366 {
+		return "[]"
+	}
+	d, err := time.Parse("2006-01-02", start)
+	if err != nil {
+		return "[]"
+	}
+	lect := lectByForm(form)
+	ui := i18n.Get(lang)
+	cfg := config.Config{UILanguage: lang, Lectionary: lect, All: true}
+
+	out := make([]daySummary, 0, count)
+	for i := 0; i < count; i++ {
+		date := d.AddDate(0, 0, i).Format("2006-01-02")
+		row := daySummary{Date: date, Parts: []summaryPart{}}
+		secs, info, err := readings.Load(cfg, readings.Options{Date: date, All: true})
+		if err != nil {
+			row.Error = err.Error()
+		} else {
+			row.Name = info.Name
+			row.Colour = info.Colour
+			row.Rank = info.Rank
+			row.RankLabel = ui.Rank[info.Rank]
+			for _, sec := range secs {
+				row.Parts = append(row.Parts, summaryPart{Part: sec.PartID, Citation: sec.Citation})
+			}
+		}
+		out = append(out, row)
+	}
+
+	b, err := json.Marshal(out)
+	if err != nil {
+		return "[]"
+	}
+	return string(b)
+}
+
 // Ping is a trivial JNI smoke test: it returns "pong" so the app can confirm the
 // native engine loaded before issuing a real query.
 func Ping() string { return "pong" }