//! Generate systemd unit files for Warpgate services.

use std::fmt::Write as _;
use std::fs;
use std::path::Path;
use std::process::Command;

use anyhow::{Context, Result};

use crate::config::Config;

/// Target directory for systemd unit files.
pub const SYSTEMD_DIR: &str = "/etc/systemd/system";

/// Single unified service unit name.
pub const RUN_SERVICE: &str = "warpgate.service";

/// Generate the single `warpgate.service` unit that runs `warpgate run`.
///
/// This replaces the old multi-unit approach. The `warpgate run` supervisor
/// manages rclone mount, SMB, NFS, and WebDAV internally.
pub fn generate_run_unit(_config: &Config) -> Result<String> {
    let mut unit = String::new();
    writeln!(unit, "# Generated by Warpgate — do not edit manually.")?;
    writeln!(unit, "[Unit]")?;
    writeln!(unit, "Description=Warpgate NAS cache proxy")?;
    writeln!(unit, "After=network-online.target")?;
    writeln!(unit, "Wants=network-online.target")?;
    writeln!(unit)?;
    writeln!(unit, "[Service]")?;
    writeln!(unit, "Type=simple")?;
    writeln!(unit, "ExecStart=/usr/local/bin/warpgate run")?;
    writeln!(unit, "Restart=on-failure")?;
    writeln!(unit, "RestartSec=10")?;
    writeln!(unit, "KillMode=mixed")?;
    writeln!(unit, "TimeoutStopSec=30")?;
    writeln!(unit)?;
    writeln!(unit, "[Install]")?;
    writeln!(unit, "WantedBy=multi-user.target")?;

    Ok(unit)
}

/// Install the single `warpgate.service` unit and reload systemd.
pub fn install_run_unit(config: &Config) -> Result<()> {
    let systemd_dir = Path::new(SYSTEMD_DIR);

    let unit_content = generate_run_unit(config)?;
    fs::write(systemd_dir.join(RUN_SERVICE), unit_content)
        .with_context(|| format!("Failed to write {RUN_SERVICE}"))?;

    // Reload systemd daemon
    let status = Command::new("systemctl")
        .arg("daemon-reload")
        .status()
        .context("Failed to run systemctl daemon-reload")?;

    if !status.success() {
        anyhow::bail!("systemctl daemon-reload failed with exit code: {}", status);
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;

    fn test_config() -> Config {
        toml::from_str(
            r#"
[[connections]]
name = "nas"
host = "10.0.0.1"
protocol = "sftp"
user = "admin"

[cache]
dir = "/tmp/cache"

[read]
[bandwidth]
[writeback]
[directory_cache]
[protocols]

[[shares]]
name = "photos"
connection = "nas"
remote_path = "/photos"
mount_point = "/mnt/photos"
"#,
        )
        .unwrap()
    }

    #[test]
    fn test_generate_run_unit_sections() {
        let config = test_config();
        let unit = generate_run_unit(&config).unwrap();

        assert!(unit.contains("[Unit]"));
        assert!(unit.contains("[Service]"));
        assert!(unit.contains("[Install]"));
    }

    #[test]
    fn test_generate_run_unit_content() {
        let config = test_config();
        let unit = generate_run_unit(&config).unwrap();

        assert!(unit.contains("Description=Warpgate NAS cache proxy"));
        assert!(unit.contains("After=network-online.target"));
        assert!(unit.contains("Type=simple"));
        assert!(unit.contains("ExecStart=/usr/local/bin/warpgate run"));
        assert!(unit.contains("Restart=on-failure"));
        assert!(unit.contains("RestartSec=10"));
        assert!(unit.contains("KillMode=mixed"));
        assert!(unit.contains("WantedBy=multi-user.target"));
    }

    #[test]
    fn test_systemd_constants() {
        assert_eq!(SYSTEMD_DIR, "/etc/systemd/system");
        assert_eq!(RUN_SERVICE, "warpgate.service");
    }
}

/// Enable and start the single `warpgate.service`.
pub fn enable_and_start_run() -> Result<()> {
    let status = Command::new("systemctl")
        .args(["enable", "--now", RUN_SERVICE])
        .status()
        .with_context(|| format!("Failed to run systemctl enable --now {RUN_SERVICE}"))?;

    if !status.success() {
        anyhow::bail!("systemctl enable --now {RUN_SERVICE} failed with exit code: {status}");
    }

    Ok(())
}