From 5a41d5008f2e723d6adccac7acf1cf522e5c0389 Mon Sep 17 00:00:00 2001
From: Elias Projahn <johrpan@gmail.com>
Date: Thu, 4 Feb 2021 16:31:37 +0100
Subject: [PATCH] Add custom error type for the backend

---
 Cargo.toml                        |  1 +
 src/backend/client/ensembles.rs   |  3 +--
 src/backend/client/instruments.rs |  3 +--
 src/backend/client/mediums.rs     |  3 +--
 src/backend/client/mod.rs         | 29 ++++++++++++++++++-----------
 src/backend/client/persons.rs     |  3 +--
 src/backend/client/recordings.rs  |  3 +--
 src/backend/client/register.rs    |  5 ++---
 src/backend/client/works.rs       |  3 +--
 src/backend/library.rs            |  3 +--
 src/backend/mod.rs                |  4 +++-
 src/backend/player.rs             | 23 +++++++++++------------
 src/backend/secure.rs             |  3 +--
 src/selectors/selector.rs         |  2 +-
 14 files changed, 44 insertions(+), 44 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index ee06113..0bba97b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,6 +22,7 @@ rand = "0.7.3"
 secret-service = "2.0.1"
 serde = { version = "1.0.117", features = ["derive"] }
 serde_json = "1.0.59"
+thiserror = "1.0.23"
 uuid = { version = "0.8", features = ["v4"] }
 
 [dependencies.gdk]
diff --git a/src/backend/client/ensembles.rs b/src/backend/client/ensembles.rs
index 20b9ea6..ed7cd3d 100644
--- a/src/backend/client/ensembles.rs
+++ b/src/backend/client/ensembles.rs
@@ -1,5 +1,4 @@
-use crate::backend::{Backend, Ensemble};
-use anyhow::Result;
+use crate::backend::{Backend, Ensemble, Result};
 
 impl Backend {
     /// Get all available ensembles from the server.
diff --git a/src/backend/client/instruments.rs b/src/backend/client/instruments.rs
index 18f0178..0e2b3ce 100644
--- a/src/backend/client/instruments.rs
+++ b/src/backend/client/instruments.rs
@@ -1,5 +1,4 @@
-use crate::backend::{Backend, Instrument};
-use anyhow::Result;
+use crate::backend::{Backend, Instrument, Result};
 
 impl Backend {
     /// Get all available instruments from the server.
diff --git a/src/backend/client/mediums.rs b/src/backend/client/mediums.rs
index fb9dc46..f346e5c 100644
--- a/src/backend/client/mediums.rs
+++ b/src/backend/client/mediums.rs
@@ -1,5 +1,4 @@
-use crate::backend::{Backend, Medium};
-use anyhow::Result;
+use crate::backend::{Backend, Medium, Result};
 
 impl Backend {
     /// Get all available mediums from the server, that contain the specified
diff --git a/src/backend/client/mod.rs b/src/backend/client/mod.rs
index f4a45f5..f87e69b 100644
--- a/src/backend/client/mod.rs
+++ b/src/backend/client/mod.rs
@@ -1,6 +1,4 @@
-use super::secure;
-use super::Backend;
-use anyhow::{anyhow, bail, Result};
+use crate::backend::{Backend, Error, Result, secure};
 use gio::prelude::*;
 use isahc::http::StatusCode;
 use isahc::prelude::*;
@@ -74,11 +72,20 @@ impl Backend {
         self.server_url.borrow().clone()
     }
 
+    /// Require the server URL to be set.
+    fn server_url(&self) -> Result<String> {
+        self.get_server_url().ok_or(Error::Other("The server URL is not available!"))
+    }
+
     /// Get the currently stored login credentials.
     pub fn get_login_data(&self) -> Option<LoginData> {
         self.login_data.borrow().clone()
     }
 
+    fn login_data(&self) -> Result<LoginData> {
+        self.get_login_data().ok_or(Error::Other("The login data is unset!"))
+    }
+
     /// Set the user credentials to use.
     pub async fn set_login_data(&self, data: LoginData) -> Result<()> {
         secure::store_login_data(data.clone()).await?;
@@ -89,8 +96,8 @@ impl Backend {
 
     /// Try to login a user with the provided credentials and return, wether the login suceeded.
     pub async fn login(&self) -> Result<bool> {
-        let server_url = self.get_server_url().ok_or(anyhow!("No server URL set!"))?;
-        let data = self.get_login_data().ok_or(anyhow!("No login data set!"))?;
+        let server_url = self.server_url()?;
+        let data = self.login_data()?;
 
         let request = Request::post(format!("{}/login", server_url))
             .timeout(Duration::from_secs(10))
@@ -106,7 +113,7 @@ impl Backend {
                 true
             }
             StatusCode::UNAUTHORIZED => false,
-            _ => bail!("Unexpected response status!"),
+            status_code => Err(Error::UnexpectedResponse(status_code))?,
         };
 
         Ok(success)
@@ -114,7 +121,7 @@ impl Backend {
 
     /// Make an unauthenticated get request to the server.
     async fn get(&self, url: &str) -> Result<String> {
-        let server_url = self.get_server_url().ok_or(anyhow!("No server URL set!"))?;
+        let server_url = self.server_url()?;
 
         let mut response = Request::get(format!("{}/{}", server_url, url))
             .timeout(Duration::from_secs(10))
@@ -138,7 +145,7 @@ impl Backend {
                     if self.login().await? {
                         response = self.post_priv(url, body).await?;
                     } else {
-                        bail!("Login failed!");
+                        Err(Error::LoginFailed)?;
                     }
                 }
 
@@ -148,7 +155,7 @@ impl Backend {
                 let mut response = if self.login().await? {
                     self.post_priv(url, body).await?
                 } else {
-                    bail!("Login failed!");
+                    Err(Error::LoginFailed)?
                 };
 
                 response.text_async().await?
@@ -160,8 +167,8 @@ impl Backend {
 
     /// Post something to the server assuming there is a valid login token.
     async fn post_priv(&self, url: &str, body: String) -> Result<Response<Body>> {
-        let server_url = self.get_server_url().ok_or(anyhow!("No server URL set!"))?;
-        let token = self.get_token().ok_or(anyhow!("No login token!"))?;
+        let server_url = self.server_url()?;
+        let token = self.get_token().ok_or(Error::Other("No login token found!"))?;
 
         let response = Request::post(format!("{}/{}", server_url, url))
             .timeout(Duration::from_secs(10))
diff --git a/src/backend/client/persons.rs b/src/backend/client/persons.rs
index 6bc0200..86aa9bd 100644
--- a/src/backend/client/persons.rs
+++ b/src/backend/client/persons.rs
@@ -1,5 +1,4 @@
-use crate::backend::{Backend, Person};
-use anyhow::Result;
+use crate::backend::{Backend, Person, Result};
 
 impl Backend {
     /// Get all available persons from the server.
diff --git a/src/backend/client/recordings.rs b/src/backend/client/recordings.rs
index 0bfe382..6fb7a69 100644
--- a/src/backend/client/recordings.rs
+++ b/src/backend/client/recordings.rs
@@ -1,5 +1,4 @@
-use crate::backend::{Backend, Recording};
-use anyhow::Result;
+use crate::backend::{Backend, Recording, Result};
 
 impl Backend {
     /// Get all available recordings from the server.
diff --git a/src/backend/client/register.rs b/src/backend/client/register.rs
index bfe639e..ee4b3b6 100644
--- a/src/backend/client/register.rs
+++ b/src/backend/client/register.rs
@@ -1,5 +1,4 @@
-use super::Backend;
-use anyhow::{anyhow, Result};
+use crate::backend::{Backend, Result};
 use isahc::http::StatusCode;
 use isahc::prelude::*;
 use serde::{Deserialize, Serialize};
@@ -35,7 +34,7 @@ impl Backend {
     /// Register a new user and return whether the process suceeded. This will
     /// not store the new login credentials.
     pub async fn register(&self, data: UserRegistration) -> Result<bool> {
-        let server_url = self.get_server_url().ok_or(anyhow!("No server URL set!"))?;
+        let server_url = self.server_url()?;
 
         let mut response = Request::post(format!("{}/users", server_url))
             .timeout(Duration::from_secs(10))
diff --git a/src/backend/client/works.rs b/src/backend/client/works.rs
index 2c6bc98..5608f36 100644
--- a/src/backend/client/works.rs
+++ b/src/backend/client/works.rs
@@ -1,5 +1,4 @@
-use crate::backend::{Backend, Work};
-use anyhow::Result;
+use crate::backend::{Backend, Result, Work};
 
 impl Backend {
     /// Get all available works from the server.
diff --git a/src/backend/library.rs b/src/backend/library.rs
index 51a4e7c..eef75e2 100644
--- a/src/backend/library.rs
+++ b/src/backend/library.rs
@@ -1,5 +1,4 @@
-use super::{Backend, BackendState, DbThread, Player};
-use anyhow::Result;
+use crate::backend::{Backend, BackendState, DbThread, Player, Result};
 use gio::prelude::*;
 use std::path::PathBuf;
 use std::rc::Rc;
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 4269e8d..bbf2426 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -1,4 +1,3 @@
-use anyhow::Result;
 use futures_channel::mpsc;
 use std::cell::RefCell;
 use std::path::PathBuf;
@@ -10,6 +9,9 @@ pub use client::*;
 pub mod database;
 pub use database::*;
 
+pub mod error;
+pub use error::*;
+
 pub mod library;
 pub use library::*;
 
diff --git a/src/backend/player.rs b/src/backend/player.rs
index a47d9ee..060c5e7 100644
--- a/src/backend/player.rs
+++ b/src/backend/player.rs
@@ -1,6 +1,4 @@
-use crate::backend::TrackSet;
-use anyhow::anyhow;
-use anyhow::Result;
+use crate::backend::{Error, Result, TrackSet};
 use gstreamer_player::prelude::*;
 use std::cell::{Cell, RefCell};
 use std::path::PathBuf;
@@ -122,9 +120,7 @@ impl Player {
 
     pub fn add_item(&self, item: PlaylistItem) -> Result<()> {
         if item.indices.is_empty() {
-            Err(anyhow!(
-                "Tried to add playlist item without tracks to playlist!"
-            ))
+            Err(Error::Other("Tried to add an empty playlist item!"))
         } else {
             let was_empty = {
                 let mut playlist = self.playlist.borrow_mut();
@@ -188,11 +184,13 @@ impl Player {
     }
 
     pub fn previous(&self) -> Result<()> {
-        let mut current_item = self.current_item.get().ok_or(anyhow!("No current item!"))?;
+        let mut current_item = self.current_item.get()
+            .ok_or(Error::Other("Player tried to access non existant current item."))?;
+
         let mut current_track = self
             .current_track
             .get()
-            .ok_or(anyhow!("No current track!"))?;
+            .ok_or(Error::Other("Player tried to access non existant current track."))?;
 
         let playlist = self.playlist.borrow();
         if current_track > 0 {
@@ -201,7 +199,7 @@ impl Player {
             current_item -= 1;
             current_track = playlist[current_item].indices.len() - 1;
         } else {
-            return Err(anyhow!("No previous track!"));
+            return Err(Error::Other("No existing previous track."));
         }
 
         self.set_track(current_item, current_track)
@@ -223,11 +221,12 @@ impl Player {
     }
 
     pub fn next(&self) -> Result<()> {
-        let mut current_item = self.current_item.get().ok_or(anyhow!("No current item!"))?;
+        let mut current_item = self.current_item.get()
+            .ok_or(Error::Other("Player tried to access non existant current item."))?;
         let mut current_track = self
             .current_track
             .get()
-            .ok_or(anyhow!("No current track!"))?;
+            .ok_or(Error::Other("Player tried to access non existant current track."))?;
 
         let playlist = self.playlist.borrow();
         let item = &playlist[current_item];
@@ -237,7 +236,7 @@ impl Player {
             current_item += 1;
             current_track = 0;
         } else {
-            return Err(anyhow!("No next track!"));
+            return Err(Error::Other("No existing previous track."));
         }
 
         self.set_track(current_item, current_track)
diff --git a/src/backend/secure.rs b/src/backend/secure.rs
index 508541d..5950651 100644
--- a/src/backend/secure.rs
+++ b/src/backend/secure.rs
@@ -1,5 +1,4 @@
-use crate::backend::LoginData;
-use anyhow::Result;
+use crate::backend::{LoginData, Result};
 use futures_channel::oneshot;
 use secret_service::{Collection, EncryptionType, SecretService};
 use std::collections::HashMap;
diff --git a/src/selectors/selector.rs b/src/selectors/selector.rs
index b6d27b5..a7bea92 100644
--- a/src/selectors/selector.rs
+++ b/src/selectors/selector.rs
@@ -1,5 +1,5 @@
+use crate::backend::Result;
 use crate::widgets::List;
-use anyhow::Result;
 use glib::clone;
 use gtk::prelude::*;
 use gtk_macros::get_widget;