feat: implement appservices

this also reverts some stateres changes

src/database/appservice.rs

@@ -0,0 +1,67 @@
+use crate::{utils, Error, Result};
+use std::collections::HashMap;
+use std::sync::{Arc, RwLock};
+
+#[derive(Clone)]
+pub struct Appservice {
+    pub(super) cached_registrations: Arc<RwLock<HashMap<String, serde_yaml::Value>>>,
+    pub(super) id_appserviceregistrations: sled::Tree,
+}
+
+impl Appservice {
+    pub fn register_appservice(&self, yaml: serde_yaml::Value) -> Result<()> {
+        // TODO: Rumaify
+        let id = yaml.get("id").unwrap().as_str().unwrap();
+        self.id_appserviceregistrations
+            .insert(id, serde_yaml::to_string(&yaml).unwrap().as_bytes())?;
+        self.cached_registrations
+            .write()
+            .unwrap()
+            .insert(id.to_owned(), yaml);
+
+        Ok(())
+    }
+
+    pub fn get_registration(&self, id: &str) -> Result<Option<serde_yaml::Value>> {
+        self.cached_registrations
+            .read()
+            .unwrap()
+            .get(id)
+            .map_or_else(
+                || {
+                    Ok(self
+                        .id_appserviceregistrations
+                        .get(id)?
+                        .map(|bytes| {
+                            Ok::<_, Error>(serde_yaml::from_slice(&bytes).map_err(|_| {
+                                Error::bad_database(
+                                    "Invalid registration bytes in id_appserviceregistrations.",
+                                )
+                            })?)
+                        })
+                        .transpose()?)
+                },
+                |r| Ok(Some(r.clone())),
+            )
+    }
+
+    pub fn iter_ids(&self) -> impl Iterator<Item = Result<String>> {
+        self.id_appserviceregistrations.iter().keys().map(|id| {
+            Ok(utils::string_from_bytes(&id?).map_err(|_| {
+                Error::bad_database("Invalid id bytes in id_appserviceregistrations.")
+            })?)
+        })
+    }
+
+    pub fn iter_all<'a>(
+        &'a self,
+    ) -> impl Iterator<Item = Result<(String, serde_yaml::Value)>> + 'a {
+        self.iter_ids().filter_map(|id| id.ok()).map(move |id| {
+            Ok((
+                id.clone(),
+                self.get_registration(&id)?
+                    .expect("iter_ids only returns appservices that exist"),
+            ))
+        })
+    }
+}