Tidy up CLI

Test Plan
=========

CI

Cargo.toml

@@ -79,3 +79,7 @@ opt-level = 3
 [[bench]]
 name = "benchmark"
 harness = false
+
+[[bin]]
+name = "lightswitch"
+path = "src/cli/main.rs"

src/cli/args.rs

@@ -0,0 +1,129 @@
+use clap::Parser;
+use std::path::PathBuf;
+use std::time::Duration;
+
+use lightswitch::profiler::ProfilerConfig;
+
+use crate::validators::parse_duration;
+use crate::validators::sample_freq_in_range;
+use crate::validators::value_is_power_of_two;
+
+#[derive(clap::ValueEnum, Debug, Clone, Default)]
+pub(crate) enum LoggingLevel {
+    Trace,
+    Debug,
+    #[default]
+    Info,
+    Warn,
+    Error,
+}
+
+#[derive(clap::ValueEnum, Debug, Clone, Default)]
+pub(crate) enum ProfileFormat {
+    None,
+    #[default]
+    FlameGraph,
+    Pprof,
+}
+
+#[derive(PartialEq, clap::ValueEnum, Debug, Clone, Default)]
+pub(crate) enum ProfileSender {
+    /// Discard the profile. Used for kernel tests.
+    None,
+    #[default]
+    LocalDisk,
+    Remote,
+}
+
+#[derive(PartialEq, clap::ValueEnum, Debug, Clone, Default)]
+pub(crate) enum Symbolizer {
+    #[default]
+    Local,
+    None,
+}
+
+#[derive(Parser, Debug)]
+pub(crate) struct CliArgs {
+    /// Specific PIDs to profile
+    #[arg(long)]
+    pub(crate) pids: Vec<i32>,
+    /// Specific TIDs to profile (these can be outside the PIDs selected above)
+    #[arg(long)]
+    pub(crate) tids: Vec<i32>,
+    /// Show unwind info for given binary
+    #[arg(long, value_name = "PATH_TO_BINARY",
+        conflicts_with_all = ["pids", "tids", "show_info", "duration", "sample_freq", "profile_name"]
+    )]
+    pub(crate) show_unwind_info: Option<String>,
+    /// Show build ID for given binary
+    #[arg(long, value_name = "PATH_TO_BINARY",
+        conflicts_with_all = ["pids", "tids", "duration",
+            "sample_freq", "profile_name"]
+    )]
+    pub(crate) show_info: Option<String>,
+    /// How long this agent will run in seconds
+    #[arg(short='D', long, default_value = ProfilerConfig::default().duration.as_secs().to_string(),
+        value_parser = parse_duration)]
+    pub(crate) duration: Duration,
+    /// Enable libbpf logs. This includes the BPF verifier output
+    #[arg(long)]
+    pub(crate) libbpf_debug: bool,
+    /// Enable BPF programs logging
+    #[arg(long)]
+    pub(crate) bpf_logging: bool,
+    /// Set lightswitch's logging level
+    #[arg(long, default_value_t, value_enum)]
+    pub(crate) logging: LoggingLevel,
+    // Verification for this option guarantees the only possible selections
+    // are prime numbers up to and including 1001
+    /// Per-CPU Sampling Frequency in Hz
+    #[arg(long, default_value_t = ProfilerConfig::default().sample_freq, value_name = "SAMPLE_FREQ_IN_HZ",
+      value_parser = sample_freq_in_range,
+    )]
+    pub(crate) sample_freq: u64,
+    /// Output file for Flame Graph in SVG format
+    #[arg(long, default_value_t, value_enum)]
+    pub(crate) profile_format: ProfileFormat,
+    /// Path for the generated profile.
+    #[arg(long)]
+    pub(crate) profile_path: Option<PathBuf>,
+    /// Name for the generated profile.
+    #[arg(long)]
+    pub(crate) profile_name: Option<PathBuf>,
+    /// Where to write the profile.
+    #[arg(long, default_value_t, value_enum)]
+    pub(crate) sender: ProfileSender,
+    #[arg(long)]
+    pub(crate) server_url: Option<String>,
+    // Buffer Sizes with defaults
+    #[arg(long, default_value_t = ProfilerConfig::default().perf_buffer_bytes, value_name = "PERF_BUFFER_BYTES",
+          help="Size of each profiler perf buffer, in bytes (must be a power of 2)",
+          value_parser = value_is_power_of_two)]
+    pub(crate) perf_buffer_bytes: usize,
+    // Print out info on eBPF map sizes
+    #[arg(long, help = "Print eBPF map sizes after creation")]
+    pub(crate) mapsize_info: bool,
+    #[arg(
+        long,
+        default_value_t = ProfilerConfig::default().mapsize_stacks,
+        help = "max number of individual stacks to capture before aggregation"
+    )]
+    pub(crate) mapsize_stacks: u32,
+    #[arg(
+        long,
+        default_value_t = ProfilerConfig::default().mapsize_aggregated_stacks,
+        help = "max number of unique stacks after aggregation"
+    )]
+    pub(crate) mapsize_aggregated_stacks: u32,
+    #[arg(
+        long,
+        default_value_t = ProfilerConfig::default().mapsize_rate_limits,
+        help = "max number of rate limit entries"
+    )]
+    pub(crate) mapsize_rate_limits: u32,
+    // Exclude myself from profiling
+    #[arg(long, help = "Do not profile the profiler (myself)")]
+    pub(crate) exclude_self: bool,
+    #[arg(long, default_value_t, value_enum)]
+    pub(crate) symbolizer: Symbolizer,
+}