# `Chime.Digest`
[🔗](https://github.com/hattoriai/chime/blob/v0.1.0-dev/lib/chime/digest.ex#L1)

The digests: one email of the notifications of a day or a week, for the
people who chose `"daily"` or `"weekly"` for a category's email
(`Chime.Preferences`).

Such an email does not go at its time: its delivery waits, as
`"digest"`, with the decisions of then made (the `:unless` and `:if`
of the notifier, the preferences). Every hour, a job finds the people
whose digest is due, in their own time zone (`:time_zone` of
`Chime.Recipient`): at the config's hour (`:at` of `:digest`, 9), every
day for a daily digest, on `:weekly_on` (Monday) for a weekly one. Each
person gets one email of all their notifications due, and each delivery
is then `"digested"`. An hour the job missed (a deploy) is made up at
the next.

The time zones need a time zone database (`tz` or `tzdata`) set as
Elixir's: `config :elixir, :time_zone_database, Tz.TimeZoneDatabase`.
Without one, every digest is at the hour in UTC.

## The email

Chime writes it from what the feed shows of each notification
(`c:Chime.Notifier.feed/2`), unless the app gives its own module
(`email: MyApp.ChimeDigest` in `:digest`):

    defmodule MyApp.ChimeDigest do
      import Swoosh.Email

      def email(recipient, items, period) do
        new()
        |> subject("Your #{period} digest: #{length(items)} notifications")
        |> html_body(MyAppWeb.Emails.digest(recipient: recipient, items: items))
      end
    end

Each item is `%{notification: %Chime.Notification{}, feed: %{title: ...}}`,
the newest first, and `period` is `"daily"` or `"weekly"` (`"daily"`
when both are due). Chime gives the email its `To:`, its `From:` and a
link to unsubscribe from every email that is not required.

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*Consult [api-reference.md](api-reference.md) for complete listing*