scaffold the CLI, logging and turn research into TODOs

src/cli.rs

@@ -0,0 +1,42 @@
+//! The Command Line Interface definition to the git-identity subcommand
+
+use clap::{ArgAction, Args, Parser, Subcommand};
+
+/// Manages multiple identities (e.g. personal, work, university, ...) in git repos for you.
+#[derive(Parser, Debug)]
+pub struct Cli {
+    #[command(flatten)]
+    pub global: GlobalArgs,
+
+    #[command(subcommand)]
+    pub command: Command,
+}
+
+impl Cli {
+    pub fn run_subcommand(self) -> anyhow::Result<()> {
+        match self.command {
+            Command::SayHello(cli) => crate::subcommands::say_hello::main(self.global, cli),
+        }
+    }
+}
+
+/// Global arguments (not specific to any subcommand)
+#[derive(Args, Debug)]
+pub struct GlobalArgs {
+    /// Increases the verbosity of the log outputs
+    ///
+    /// The RUST_LOG environment variable takes priority if both are specified.
+    #[arg(short, long = "verbose", action = ArgAction::Count)]
+    pub verbosity: u8,
+}
+
+#[derive(Subcommand, Debug)]
+pub enum Command {
+    SayHello(SayHelloCli),
+}
+
+/// A temporary subcommand for testing the cli
+#[derive(Parser, Debug)]
+pub struct SayHelloCli {
+    pub name: String,
+}