From ec804134c33aedb001c426c5f42f43f53c47848f Mon Sep 17 00:00:00 2001
From: Owen Jacobson <owen@grimoire.ca>
Date: Wed, 2 Oct 2024 12:25:36 -0400
Subject: Represent channels and messages using a split "History" and
 "Snapshot" model.

This separates the code that figures out what happened to an entity from the code that represents it to a user, and makes it easier to compute a snapshot at a point in time (for things like bootstrap). It also makes the internal logic a bit easier to follow, since it's easier to tell whether you're working with a point in time or with the whole recorded history.

This hefty.
---
 src/message/repo.rs | 214 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 214 insertions(+)
 create mode 100644 src/message/repo.rs

(limited to 'src/message/repo.rs')

diff --git a/src/message/repo.rs b/src/message/repo.rs
new file mode 100644
index 0000000..3b2b8f7
--- /dev/null
+++ b/src/message/repo.rs
@@ -0,0 +1,214 @@
+use sqlx::{sqlite::Sqlite, SqliteConnection, Transaction};
+
+use super::{snapshot::Message, History, Id};
+use crate::{
+    channel::{self, Channel},
+    clock::DateTime,
+    event::{Instant, Sequence},
+    login::{self, Login},
+};
+
+pub trait Provider {
+    fn messages(&mut self) -> Messages;
+}
+
+impl<'c> Provider for Transaction<'c, Sqlite> {
+    fn messages(&mut self) -> Messages {
+        Messages(self)
+    }
+}
+
+pub struct Messages<'t>(&'t mut SqliteConnection);
+
+impl<'c> Messages<'c> {
+    pub async fn create(
+        &mut self,
+        channel: &Channel,
+        sender: &Login,
+        sent: &Instant,
+        body: &str,
+    ) -> Result<History, sqlx::Error> {
+        let id = Id::generate();
+
+        let message = sqlx::query!(
+            r#"
+				insert into message
+					(id, channel, sender, sent_at, sent_sequence, body)
+				values ($1, $2, $3, $4, $5, $6)
+				returning
+					id as "id: Id",
+					body
+			"#,
+            id,
+            channel.id,
+            sender.id,
+            sent.at,
+            sent.sequence,
+            body,
+        )
+        .map(|row| History {
+            message: Message {
+                channel: channel.clone(),
+                sender: sender.clone(),
+                id: row.id,
+                body: row.body,
+            },
+            sent: *sent,
+            deleted: None,
+        })
+        .fetch_one(&mut *self.0)
+        .await?;
+
+        Ok(message)
+    }
+
+    async fn by_id(&mut self, channel: &Channel, message: &Id) -> Result<History, sqlx::Error> {
+        let message = sqlx::query!(
+            r#"
+                select
+                    channel.id as "channel_id: channel::Id",
+                    channel.name as "channel_name",
+                    sender.id as "sender_id: login::Id",
+                    sender.name as "sender_name",
+                    message.id as "id: Id",
+                    message.body,
+                    sent_at as "sent_at: DateTime",
+                    sent_sequence as "sent_sequence: Sequence"
+                from message
+                    join channel on message.channel = channel.id
+                    join login as sender on message.sender = sender.id
+                where message.id = $1
+                    and message.channel = $2
+            "#,
+            message,
+            channel.id,
+        )
+        .map(|row| History {
+            message: Message {
+                channel: Channel {
+                    id: row.channel_id,
+                    name: row.channel_name,
+                },
+                sender: Login {
+                    id: row.sender_id,
+                    name: row.sender_name,
+                },
+                id: row.id,
+                body: row.body,
+            },
+            sent: Instant {
+                at: row.sent_at,
+                sequence: row.sent_sequence,
+            },
+            deleted: None,
+        })
+        .fetch_one(&mut *self.0)
+        .await?;
+
+        Ok(message)
+    }
+
+    pub async fn delete(
+        &mut self,
+        channel: &Channel,
+        message: &Id,
+        deleted: &Instant,
+    ) -> Result<History, sqlx::Error> {
+        let history = self.by_id(channel, message).await?;
+
+        sqlx::query_scalar!(
+            r#"
+                delete from message
+                where
+                    id = $1
+                returning 1 as "deleted: i64"
+            "#,
+            history.message.id,
+        )
+        .fetch_one(&mut *self.0)
+        .await?;
+
+        Ok(History {
+            deleted: Some(*deleted),
+            ..history
+        })
+    }
+
+    pub async fn expired(
+        &mut self,
+        expire_at: &DateTime,
+    ) -> Result<Vec<(Channel, Id)>, sqlx::Error> {
+        let messages = sqlx::query!(
+            r#"
+                select
+                    channel.id as "channel_id: channel::Id",
+                    channel.name as "channel_name",
+                    message.id as "message: Id"
+                from message
+                    join channel on message.channel = channel.id
+                where sent_at < $1
+            "#,
+            expire_at,
+        )
+        .map(|row| {
+            (
+                Channel {
+                    id: row.channel_id,
+                    name: row.channel_name,
+                },
+                row.message,
+            )
+        })
+        .fetch_all(&mut *self.0)
+        .await?;
+
+        Ok(messages)
+    }
+
+    pub async fn replay(
+        &mut self,
+        resume_at: Option<Sequence>,
+    ) -> Result<Vec<History>, sqlx::Error> {
+        let messages = sqlx::query!(
+            r#"
+                select
+                    channel.id as "channel_id: channel::Id",
+                    channel.name as "channel_name",
+                    sender.id as "sender_id: login::Id",
+                    sender.name as "sender_name",
+                    message.id as "id: Id",
+                    message.body,
+                    sent_at as "sent_at: DateTime",
+                    sent_sequence as "sent_sequence: Sequence"
+                from message
+                    join channel on message.channel = channel.id
+                    join login as sender on message.sender = sender.id
+                where coalesce(message.sent_sequence > $1, true)
+            "#,
+            resume_at,
+        )
+        .map(|row| History {
+            message: Message {
+                channel: Channel {
+                    id: row.channel_id,
+                    name: row.channel_name,
+                },
+                sender: Login {
+                    id: row.sender_id,
+                    name: row.sender_name,
+                },
+                id: row.id,
+                body: row.body,
+            },
+            sent: Instant {
+                at: row.sent_at,
+                sequence: row.sent_sequence,
+            },
+            deleted: None,
+        })
+        .fetch_all(&mut *self.0)
+        .await?;
+
+        Ok(messages)
+    }
+}
-- 
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