1 files changed, 103 insertions, 0 deletions

diff --git a/src/client/paths.rs b/src/client/paths.rs
new file mode 100644
index 0000000..b6b8d1f
--- /dev/null
+++ b/src/client/paths.rs
@@ -0,0 +1,103 @@
+//! Client data location and command-line arguments.
+
+use std::ffi::OsStr;
+use std::path::{Path, PathBuf};
+
+pub const APP_DIR: &str = "zagan-bet";
+pub const DATABASE_FILE: &str = "client.db";
+
+pub const USAGE: &str = "\
+usage: client [-d <dir>] [--unsafe]
+
+  -d, --data-dir <dir>   where to keep client.db (default: XDG data dir)
+      --unsafe           skip certificate verification
+  -h, --help             show this message
+
+The database lives in $XDG_DATA_HOME/zagan-bet/client.db, falling back to
+~/.local/share/zagan-bet/client.db (or %APPDATA%\\zagan-bet on Windows).";
+
+#[derive(Debug, Default, PartialEq, Eq)]
+pub struct ClientArgs {
+    pub unsafe_mode: bool,
+    pub data_dir: Option<PathBuf>,
+    pub help: bool,
+}
+
+/// Parse arguments, without the program name.
+pub fn parse_args(args: impl IntoIterator<Item = String>) -> Result<ClientArgs, String> {
+    let mut parsed = ClientArgs::default();
+    let mut args = args.into_iter();
+
+    while let Some(argument) = args.next() {
+        match argument.as_str() {
+            "-d" | "--data-dir" => {
+                let Some(value) = args.next() else {
+                    return Err(format!("{argument} needs a directory\n{USAGE}"));
+                };
+                if value.is_empty() {
+                    return Err(format!("{argument} needs a directory\n{USAGE}"));
+                }
+                parsed.data_dir = Some(PathBuf::from(value));
+            }
+            "--unsafe" => parsed.unsafe_mode = true,
+            "-h" | "--help" => parsed.help = true,
+            _ => {
+                if let Some(value) = argument.strip_prefix("--data-dir=") {
+                    if value.is_empty() {
+                        return Err(format!("--data-dir needs a directory\n{USAGE}"));
+                    }
+                    parsed.data_dir = Some(PathBuf::from(value));
+                } else {
+                    return Err(format!("unknown argument: {argument}\n{USAGE}"));
+                }
+            }
+        }
+    }
+
+    Ok(parsed)
+}
+
+/// `$XDG_DATA_HOME/zagan-bet`, `%APPDATA%\zagan-bet`, or
+/// `$HOME/.local/share/zagan-bet`, in that order.
+pub fn data_dir_from(
+    xdg_data_home: Option<&OsStr>,
+    home: Option<&OsStr>,
+    appdata: Option<&OsStr>,
+) -> PathBuf {
+    if let Some(xdg) = xdg_data_home {
+        let path = Path::new(xdg);
+        // The XDG spec says a relative XDG_DATA_HOME is invalid.
+        if !xdg.is_empty() && path.is_absolute() {
+            return path.join(APP_DIR);
+        }
+    }
+
+    if let Some(appdata) = appdata {
+        let path = Path::new(appdata);
+        if !appdata.is_empty() && path.is_absolute() {
+            return path.join(APP_DIR);
+        }
+    }
+
+    if let Some(home) = home {
+        let path = Path::new(home);
+        if !home.is_empty() && path.is_absolute() {
+            return path.join(".local").join("share").join(APP_DIR);
+        }
+    }
+
+    // No usable home directory: keep the old behaviour and stay local.
+    PathBuf::from(APP_DIR)
+}
+
+pub fn default_data_dir() -> PathBuf {
+    data_dir_from(
+        std::env::var_os("XDG_DATA_HOME").as_deref(),
+        std::env::var_os("HOME").as_deref(),
+        std::env::var_os("APPDATA").as_deref(),
+    )
+}
+
+pub fn database_path(data_dir: &Path) -> PathBuf {
+    data_dir.join(DATABASE_FILE)
+}