Logging + database migrations system.

src/database/migrations/init.rs

@@ -0,0 +1,39 @@
+use super::super::get_db;
+use super::scripts::LATEST_REVISION;
+
+use mongodb::options::CreateCollectionOptions;
+use mongodb::bson::doc;
+use log::info;
+
+pub fn create_database() {
+    info!("Creating database.");
+    let db = get_db();
+
+    db.create_collection("users", None).expect("Failed to create users collection.");
+    db.create_collection("channels", None).expect("Failed to create channels collection.");
+    db.create_collection("guilds", None).expect("Failed to create guilds collection.");
+    db.create_collection("members", None).expect("Failed to create members collection.");
+    db.create_collection("messages", None).expect("Failed to create messages collection.");
+    db.create_collection("migrations", None).expect("Failed to create migrations collection.");
+
+    db.create_collection(
+        "pubsub",
+        CreateCollectionOptions::builder()
+            .capped(true)
+            .size(1_000_000)
+            .build()
+    )
+    .expect("Failed to create pubsub collection.");
+
+    db.collection("migrations")
+        .insert_one(
+            doc! {
+                "_id": 0,
+                "revision": LATEST_REVISION
+            },
+            None
+        )
+        .expect("Failed to save migration info.");
+    
+    info!("Created database.");
+}

src/database/migrations/mod.rs

@@ -0,0 +1,19 @@
+use super::get_connection;
+
+pub mod init;
+pub mod scripts;
+
+pub fn run_migrations() {
+    let client = get_connection();
+
+    let list = client.list_database_names(
+        None,
+        None
+    ).expect("Failed to fetch database names.");
+
+    if list.iter().position(|x| x == "revolt").is_none() {
+        init::create_database();
+    } else {
+        scripts::migrate_database();
+    }
+}

src/database/migrations/scripts.rs

@@ -0,0 +1,53 @@
+use super::super::get_collection;
+
+use serde::{Serialize, Deserialize};
+use mongodb::bson::{Bson, from_bson, doc};
+use log::info;
+
+#[derive(Serialize, Deserialize)]
+struct MigrationInfo {
+    _id: i32,
+    revision: i32
+}
+
+pub const LATEST_REVISION: i32 = 1;
+
+pub fn migrate_database() {
+    let migrations = get_collection("migrations");
+    let data = migrations.find_one(None, None)
+        .expect("Failed to fetch migration data.");
+    
+    if let Some(doc) = data {
+        let info: MigrationInfo = from_bson(Bson::Document(doc))
+            .expect("Failed to read migration information.");
+        
+        let revision = run_migrations(info.revision);
+
+        migrations.update_one(
+            doc! {
+                "_id": info._id
+            },
+            doc! {
+                "$set": {
+                    "revision": revision
+                }
+            },
+            None
+        ).expect("Failed to commit migration information.");
+
+        info!("Migration complete. Currently at revision {}.", revision);
+    } else {
+        panic!("Database was configured incorrectly, possibly because initalization failed.")
+    }
+}
+
+pub fn run_migrations(revision: i32) -> i32 {
+    info!("Starting database migration.");
+
+    if revision <= 0 {
+        info!("Running migration [revision 0]: Test migration system.");
+    }
+
+    // Reminder to update LATEST_REVISION when adding new migrations.
+    LATEST_REVISION
+}