//! Integration with `clap`
//!
//! CLI argument structs are defined in this module. Execution logic for each
//! command goes in a submodule.

use std::path::PathBuf;

use clap::{Parser, Subcommand};

use crate::{
    config::{default_tracing_filter, EnvFilterClone, LogFormat},
    error, observability,
};

mod check_config;
mod get_room_states;
mod serve;

/// Command line arguments
#[derive(Parser)]
#[clap(
    about,
    version = crate::version(),
)]
pub(crate) struct Args {
    #[clap(subcommand)]
    pub(crate) command: Command,
}

#[derive(Subcommand)]
pub(crate) enum Command {
    /// Run the server.
    Serve(ServeArgs),

    /// Check the configuration file for syntax and semantic errors.
    CheckConfig(CheckConfigArgs),

    /// Write the state of all rooms as JSON to stdout.
    ///
    /// This is primarily useful for debugging.
    GetRoomStates(GetRoomStatesArgs),
}

#[derive(clap::Args)]
pub(crate) struct CheckConfigArgs {
    #[clap(flatten)]
    config: ConfigArg,

    #[clap(flatten)]
    observability: ObservabilityArgs,
}

/// Wrapper for the `--config` arg.
///
/// This exists to centralize the `mut_arg` code that sets the help value based
/// on runtime information.
#[derive(clap::Args)]
#[clap(mut_arg("config", |x| {
    let help = "Set the path to the configuration file";
    x.help(help).long_help(format!(
        "{}\n\nIf this option is specified, the provided value is used \
         as-is.\n\nIf this option is not specified, then the XDG Base \
         Directory Specification is followed, searching for the path `{}` \
         in the configuration directories.
        ",
        help,
        crate::config::DEFAULT_PATH.display(),
    ))
}))]
pub(crate) struct ConfigArg {
    /// Path to the configuration file
    #[clap(long, short)]
    pub(crate) config: Option<PathBuf>,
}

/// Observability arguments for CLI subcommands
#[derive(clap::Args)]
struct ObservabilityArgs {
    /// Log format
    #[clap(long, default_value_t = LogFormat::Full)]
    log_format: LogFormat,

    /// Log filter
    ///
    /// For information about the syntax, see here:
    /// <https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html#directives>
    #[clap(long, default_value_t = default_tracing_filter())]
    log_filter: EnvFilterClone,
}

#[derive(clap::Args)]
pub(crate) struct ServeArgs {
    #[clap(flatten)]
    pub(crate) config: ConfigArg,
}

#[derive(clap::Args)]
pub(crate) struct GetRoomStatesArgs {
    #[clap(flatten)]
    pub(crate) config: ConfigArg,

    #[clap(flatten)]
    observability: ObservabilityArgs,
}

impl Args {
    pub(crate) async fn run(self) -> Result<(), error::Main> {
        if let Some((format, filter)) = self.command.cli_observability_args() {
            observability::init_for_cli(format, filter.into())?;
        }

        match self.command {
            Command::Serve(args) => serve::run(args).await?,
            Command::CheckConfig(args) => {
                check_config::run(args.config).await?;
            }
            Command::GetRoomStates(args) => get_room_states::run(args).await?,
        }
        Ok(())
    }
}

impl Command {
    fn cli_observability_args(&self) -> Option<(LogFormat, EnvFilterClone)> {
        // All subcommands other than `serve` should return `Some`. Keep these
        // match arms sorted by the enum variant name.
        match self {
            Command::CheckConfig(args) => Some((
                args.observability.log_format,
                args.observability.log_filter.clone(),
            )),
            Command::GetRoomStates(args) => Some((
                args.observability.log_format,
                args.observability.log_filter.clone(),
            )),
            Command::Serve(_) => None,
        }
    }
}