feat: Add backend code for getting playercount (#135)

* feat: Initial backend code to get the playercount
from the Northstar master server together with servercount

* fix: Push correct backend code

* feat: Load playercount on application load
and show on PlayView

* refactor: Store global const in separate file

Moved user agent there for now

* refactor: User user agent from global const

* refactor: Move masterserver URL into global const

* refactor: Remove temporary variable

* fix: Do proper typing for playercount return value

* feat: Change text if unable to load playercount

So instead of showing some wrong value, we just say that we were unable
to load it.

* fix: Remove leftover print statement

* refactor: Move struct to library source file

* fix: Remove break element

* fix: Remove frontend display of playercount

This allows for separate PR for adding backend code early.

* refactor: serverlist endpoint var to global const

3 files changed, 46 insertions, 1 deletions

diff --git a/src-tauri/src/constants.rs b/src-tauri/src/constants.rs
index 9d7e117c..4cc3c204 100644
--- a/src-tauri/src/constants.rs
+++ b/src-tauri/src/constants.rs
@@ -1,3 +1,9 @@
 // This file stores various global constants values
 
 pub const APP_USER_AGENT: &str = "R2NorthstarTools/FlightCore";
+
+// URL of the Northstar masterserver
+pub const MASTER_SERVER_URL: &str = "https://northstar.tf";
+
+// server list endpoint
+pub const SERVER_BROWSER_ENDPOINT: &str = "/client/servers";
diff --git a/src-tauri/src/lib.rs b/src-tauri/src/lib.rs
index 2df1e243..67f42f85 100644
--- a/src-tauri/src/lib.rs
+++ b/src-tauri/src/lib.rs
@@ -39,6 +39,12 @@ pub struct NorthstarMod {
     pub directory: String,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct NorthstarServer {
+    #[serde(rename = "playerCount")]
+    pub player_count: i32,
+}
+
 /// Check version number of a mod
 pub fn check_mod_version_number(path_to_mod_folder: String) -> Result<String, anyhow::Error> {
     // println!("{}", format!("{}/mod.json", path_to_mod_folder));
diff --git a/src-tauri/src/main.rs b/src-tauri/src/main.rs
index 96be489f..b47a796e 100644
--- a/src-tauri/src/main.rs
+++ b/src-tauri/src/main.rs
@@ -9,7 +9,7 @@ use std::{
     time::Duration,
 };
 
-use app::*;
+use app::{*, constants::{APP_USER_AGENT, MASTER_SERVER_URL, SERVER_BROWSER_ENDPOINT}};
 
 mod github;
 use github::release_notes::{
@@ -30,6 +30,7 @@ use mod_management::{
 mod northstar;
 use northstar::get_northstar_version_number;
 
+use serde::{Deserialize, Serialize};
 use tauri::Manager;
 use tauri_plugin_store::PluginBuilder;
 use tokio::time::sleep;
@@ -105,6 +106,7 @@ fn main() {
             clean_up_download_folder_caller,
             get_newest_flightcore_version,
             delete_northstar_mod,
+            get_server_player_count,
             delete_thunderstore_mod,
         ])
         .run(tauri::generate_context!())
@@ -307,3 +309,34 @@ async fn clean_up_download_folder_caller(
         Err(err) => Err(err.to_string()),
     }
 }
+
+
+/// Gets server and playercount from master server API
+#[tauri::command]
+async fn get_server_player_count() -> Result<(i32, usize), String> {
+
+    let url = format!("{MASTER_SERVER_URL}{SERVER_BROWSER_ENDPOINT}");
+    let client = reqwest::Client::new();
+    let res = client
+        .get(url)
+        .header(reqwest::header::USER_AGENT, APP_USER_AGENT)
+        .send()
+        .await
+        .unwrap()
+        .text()
+        .await
+        .unwrap();
+
+    let ns_servers: Vec<NorthstarServer> =
+        serde_json::from_str(&res).expect("JSON was not well-formatted");
+
+    // Get server count
+    let server_count = ns_servers.len();
+
+    // Sum up player count
+    let total_player_count: i32 = ns_servers.iter().map(|server| server.player_count).sum();
+
+    dbg!((total_player_count, server_count));
+
+    Ok((total_player_count, server_count))
+}