parse_args: commandline parsing module

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

src/parse_args.rs

@@ -0,0 +1,138 @@
+use viperus::Viperus;
+
+/// The given Viperus structure will be muted according to the
+/// processed default, environment and commandline arguments
+pub fn parse_args(v: &mut Viperus) -> Result<(), Box<dyn std::error::Error>> {
+    //use log::{debug, info, trace, warn};
+    use log::trace;
+    use std::env;
+
+    if cfg!(feature = "yaml") {
+	trace!(target:"feature", "Clap feature 'yaml' enabled.");
+	println!("Using feature yaml.");
+    }
+    if cfg!(feature = "fmt-clap") {
+	trace!(target: "Viperus", "Viperus feature 'fmt-clap' enabled.");
+	println!("Using feature fmt-clap");
+    }
+
+    // preset default key/value pairs (lowest priority)
+    v.add_default("config_file", String::from("advotrackerd.yml"));
+    v.add_default("db_driver", String::from("sqlite"));
+    v.add_default("verbose", 0);
+
+    //if cfg!(feature = "fmt-clap") {
+    println!("With fmt-clap...");
+
+    // parse CLI commandline arguments with clap
+    use clap::{crate_authors, crate_description, crate_name, crate_version, App, Arg};
+
+    // CLI arguments are defined inline
+    let matches = App::new("advotrackerd")
+	.name(crate_name!())
+	.version(crate_version!())
+	.author(crate_authors!())
+	.about(crate_description!())
+	.after_help("in Zusammenarbeit mit Hiedemann Rechtsanwälte <info@hiedemann.de>")
+	.template(
+	    "\
+		    {bin} v{version}
+{about}
+
+{all-args}
+
+(C) 2020 {author}
+{after_help}",
+	)
+	.arg(
+	    Arg::with_name("configFile")
+		.short("c")
+		.long("configFile")
+		.value_name("FILE")
+		.help("Sets a custom config file")
+		.takes_value(true),
+	)
+	.arg(
+	    Arg::with_name("dbdriver")
+		.short("d")
+		.long("dbdriver")
+		.value_name("DatabaseDriver")
+		.help("Driver used to connect to database")
+		.possible_values(&["mysql", "postgres", "sqlite"])
+		.takes_value(true),
+	)
+	.arg(
+	    Arg::with_name("verbose")
+		.short("v")
+		.long("verbose")
+		.help("Sets verbosity level")
+		.multiple(true),
+	)
+	.get_matches();
+    //}
+    if matches.occurrences_of("verbose") > 0 {
+	// clap is using i64, viperus i32
+	let n = matches.occurrences_of("verbose") as i32;
+	v.add("verbose", n);
+    }
+    //}
+
+    // preset the prefix for relevant environment variables ("ADVOTRACKERD_")
+    //if cfg!(feature = "fmt-clap") {
+    let mut env_prefix: String = crate_name!().to_uppercase();
+    env_prefix.push_str("_");
+    v.set_env_prefix(&env_prefix);
+    //}
+
+    // respect dotenv environment (e.g for testing)
+    // -> overwrites the preset default values
+    println!(
+	"RUST_LOG={}",
+	dotenv::var("RUST_LOG").unwrap_or_else(|_| String::from("None"))
+    );
+    //v.load_file(".env", v.Format::ENV).unwrap();
+
+    // enable caching and automatic update of environment values
+    if cfg!(feature = "fmt-cache") {
+	v.cache(true);
+    }
+    if cfg!(feature = "fmt-env") {
+	v.automatic_env(true);
+    }
+
+    //if cfg!(feature = "fmt-clap") {
+    // load user selected call arguments
+    // -> overwrites values given via environment variables
+    v.load_clap(matches)?;
+
+    // bond the clap names to camel_case rust variable names
+    v.bond_clap("configFile", "config_file");
+    v.bond_clap("dbdriver", "db_driver");
+    v.bond_clap("verbose", "verbose");
+    //}
+
+    trace!("verbose {:?}", v.get::<i32>("verbose").unwrap());
+    if v.get::<i32>("verbose").unwrap() > 0 {
+	println!(
+	    "config_file: {:?}",
+	    v.get::<String>("config_file").unwrap_or_default()
+	);
+	println!(
+	    "db_driver: {:?}",
+	    v.get::<String>("db_driver").unwrap_or_default()
+	);
+	println!(
+	    "verbosity level: {:?}",
+	    v.get::<i32>("verbose").unwrap_or_default()
+	);
+    }
+
+    if v.get::<i32>("verbose").unwrap() > 1 {
+	println!("\nEnvironment:");
+	for (key, value) in env::vars() {
+	    println!("{}={}", key, value);
+	}
+    }
+
+    Ok(())
+}