package calfeed

import (
	"encoding/json"

	"github.com/lukaszkasprzak/lectio/internal/config"
)

const Schema = "lectio.calendar/1"

// JSON renders days as the stable lectio.calendar/1 envelope.
//
// "source" and "license" carry the AGPL-3.0 §13 offer to consumers who only
// ever see this endpoint and never load the HTML UI. They are envelope
// metadata, not day data -- adding them does not change the schema version,
// since existing consumers read "days".
func JSON(form string, days []DayView) ([]byte, error) {
	if days == nil {
		days = []DayView{}
	}
	return json.MarshalIndent(struct {
		Schema  string    `json:"schema"`
		Form    string    `json:"form"`
		Source  string    `json:"source"`
		License string    `json:"license"`
		Days    []DayView `json:"days"`
	}{Schema, form, config.SourceURL, config.License, days}, "", "  ")
}