//! `generate` subcommand - generates a skeleton config.

use crate::config::ZebradConfig;
use abscissa_core::{Command, Options, Runnable};

/// `generate` subcommand
#[derive(Command, Debug, Options)]
pub struct GenerateCmd {
    /// The file to write the generated config to.
    #[options(help = "The file to write the generated config to (stdout if unspecified)")]
    output_file: Option<String>,
}

impl Runnable for GenerateCmd {
    /// Start the application.
    fn run(&self) {
        let default_config = ZebradConfig::default();
        let mut output = r"# Default configuration for zebrad.
#
# This file can be used as a skeleton for custom configs.
#
# Unspecified fields use default values. Optional fields are Some(field) if the
# field is present and None if it is absent.
#
# This file is generated as an example using zebrad's current defaults.
# You should set only the config options you want to keep, and delete the rest.
# Only a subset of fields are present in the skeleton, since optional values
# whose default is None are omitted.
#
# The config format (including a complete list of sections and fields) is
# documented here:
# https://doc.zebra.zfnd.org/zebrad/config/struct.ZebradConfig.html
#
# zebrad attempts to load configs in the following order:
#
# 1. The -c flag on the command line, e.g., `zebrad -c myconfig.toml start`;
# 2. The file `zebrad.toml` in the users's preference directory (platform-dependent);
# 3. The default config.

"
        .to_owned();

        // this avoids a ValueAfterTable error
        // https://github.com/alexcrichton/toml-rs/issues/145
        let conf = toml::Value::try_from(default_config).unwrap();
        output += &toml::to_string_pretty(&conf).expect("default config should be serializable");
        match self.output_file {
            Some(ref output_file) => {
                use std::{fs::File, io::Write};
                File::create(output_file)
                    .expect("must be able to open output file")
                    .write_all(output.as_bytes())
                    .expect("must be able to write output");
            }
            None => {
                println!("{}", output);
            }
        }
    }
}