Add support for a configuration file

src/args.rs

@@ -1,51 +1,66 @@
 use std::path::PathBuf;
 
 use clap::{command, Parser, Subcommand};
+use serde::Serialize;
 
-#[derive(Parser)]
+#[derive(Parser, Serialize)]
 #[command(version, about, long_about = None)]
 pub(crate) struct Opts {
+    /// The Immich API URL - it should probably end in "/api"
     #[arg(short, long)]
-    pub server_url: String,
+    #[serde(skip_serializing_if = "::std::option::Option::is_none")]
+    pub server_url: Option<String>,
 
+    /// The Immich API key
     #[arg(short, long)]
-    pub api_key: String,
+    #[serde(skip_serializing_if = "::std::option::Option::is_none")]
+    pub api_key: Option<String>,
 
+    /// If enabled, actions that would have been performed are only logged
     #[arg(short, long)]
     pub dry_run: bool,
 
     #[command(subcommand)]
+    #[serde(flatten)]
     pub command: Commands,
 }
 
-#[derive(Subcommand)]
+#[derive(Serialize, Subcommand)]
 pub(crate) enum Commands {
     /// People related commands
+    #[serde(rename = "people")]
     People {
         #[command(subcommand)]
+        #[serde(flatten)]
         people_command: PeopleCommands,
     },
     /// Server related commands
+    #[serde(rename = "server")]
     Server {
         #[command(subcommand)]
+        #[serde(flatten)]
         server_command: ServerCommands,
     },
 }
 
-#[derive(Subcommand)]
+#[derive(Serialize, Subcommand)]
 pub(crate) enum PeopleCommands {
     /// Synchronises date of births from a vcard file
+    #[serde(rename = "sync_date_of_births")]
     SyncDateOfBirths {
         #[arg(short, long)]
-        vcard_file: PathBuf,
+        #[serde(skip_serializing_if = "::std::option::Option::is_none")]
+        vcard: Option<PathBuf>,
     },
 
     /// Lists the people without date of birth
+    #[serde(rename = "missing_date_of_births")]
     MissingDateOfBirths {},
 }
 
-#[derive(Subcommand)]
+#[derive(Serialize, Subcommand)]
 pub(crate) enum ServerCommands {
     /// Fetches the version of the server
+    #[serde(rename = "version")]
     Version {},
 }