Add creating new personal chats

src/graphql.rs

@@ -3,6 +3,7 @@ use std::{
         TryFrom,
         TryInto,
     },
+    collections::BTreeSet,
     fmt::Display,
     str::FromStr,
 };
@@ -520,6 +521,56 @@ impl Mutation {
 
         Ok(ID::new(id_to_uuid(&user.id)?.to_simple().to_string()))
     }
+
+    async fn newChat(context: &Context, user: ID, password_hash: String, with: ID) -> FieldResult<ID> {
+        let user = id_to_uuid(&user)?.to_simple();
+        let chat_partner = id_to_uuid(&with)?.to_simple();
+        // Sort users
+        let users = BTreeSet::from_iter([user, chat_partner]);
+
+        // User authentication
+        let authentication_successful = sqlx::query(format!(
+            r#"SELECT users.id FROM users, security_preferences WHERE users.id = "{}" AND password_hash = "{}""#,
+            user,
+            password_hash,
+        ).as_str()).fetch_optional(&context.db).await?.is_some();
+        if !authentication_successful {
+            return Err("authentication failed".into());
+        }
+
+        // Chat partner needs to be another user (for now)
+        if user == chat_partner {
+            return Err("chat partner is the same user".into());
+        }
+
+        // Chat partner must exist
+        let chat_partner_exists = sqlx::query(
+            format!(r#"SELECT id FROM users WHERE id = "{}""#, chat_partner).as_str()
+        ).fetch_optional(&context.db).await?.is_some();
+        if !chat_partner_exists {
+            return Err(format!(r#"chat partner "{}" does not exist on this server"#, chat_partner).into());
+        }
+
+        // non-group chats must be unique
+        let chat_already_exists = sqlx::query(format!(
+            r#"SELECT id FROM chat_index WHERE is_group_chat = 0 AND users = "{}""#,
+            format_array_for_sql(&users),
+        ).as_str()).fetch_optional(&context.db).await?.is_some();
+        if chat_already_exists {
+            return Err("a personal chat with this chat partner already exists".into());
+        }
+
+        // create new personal chat
+        let chat_uuid = Uuid::new_v4();
+        sqlx::query(format!(
+            r#"INSERT INTO chat_index VALUES ("{}", 0, "{}", NULL, "{1}")"#,
+            chat_uuid.to_simple(),
+            format_array_for_sql(users),
+        ).as_str()).execute(&context.db).await?;
+        crate::sqlite::create_chat(&context.db, &chat_uuid).await?;
+
+        Ok(chat_uuid.to_simple().to_string().into())
+    }
 }
 
 pub type Schema<'root_node> = RootNode<'root_node, Query, Mutation, EmptySubscription<Context>>;