use crate::{ServiceConfig, ServiceManager, ServiceManagerError, ServiceStatus};
use std::fs;
use std::path::PathBuf;
use std::process::Command;

#[derive(Debug)]
pub struct SystemdServiceManager {
    service_prefix: String,
    user_mode: bool,
}

impl SystemdServiceManager {
    pub fn new() -> Self {
        Self {
            service_prefix: "sal".to_string(),
            user_mode: true, // Default to user services for safety
        }
    }

    pub fn new_system() -> Self {
        Self {
            service_prefix: "sal".to_string(),
            user_mode: false, // System-wide services (requires root)
        }
    }

    fn get_service_name(&self, service_name: &str) -> String {
        format!("{}-{}.service", self.service_prefix, service_name)
    }

    fn get_unit_file_path(&self, service_name: &str) -> PathBuf {
        let service_file = self.get_service_name(service_name);
        if self.user_mode {
            // User service directory
            let home = std::env::var("HOME").unwrap_or_else(|_| "/tmp".to_string());
            PathBuf::from(home)
                .join(".config")
                .join("systemd")
                .join("user")
                .join(service_file)
        } else {
            // System service directory
            PathBuf::from("/etc/systemd/system").join(service_file)
        }
    }

    fn run_systemctl(&self, args: &[&str]) -> Result<String, ServiceManagerError> {
        let mut cmd = Command::new("systemctl");

        if self.user_mode {
            cmd.arg("--user");
        }

        cmd.args(args);

        let output = cmd
            .output()
            .map_err(|e| ServiceManagerError::Other(format!("Failed to run systemctl: {}", e)))?;

        if !output.status.success() {
            let stderr = String::from_utf8_lossy(&output.stderr);
            return Err(ServiceManagerError::Other(format!(
                "systemctl command failed: {}",
                stderr
            )));
        }

        Ok(String::from_utf8_lossy(&output.stdout).to_string())
    }

    fn create_unit_file(&self, config: &ServiceConfig) -> Result<(), ServiceManagerError> {
        let unit_path = self.get_unit_file_path(&config.name);

        // Ensure the directory exists
        if let Some(parent) = unit_path.parent() {
            fs::create_dir_all(parent).map_err(|e| {
                ServiceManagerError::Other(format!("Failed to create unit directory: {}", e))
            })?;
        }

        // Create the unit file content
        let mut unit_content = String::new();
        unit_content.push_str("[Unit]\n");
        unit_content.push_str(&format!("Description={} service\n", config.name));
        unit_content.push_str("After=network.target\n\n");

        unit_content.push_str("[Service]\n");
        unit_content.push_str("Type=simple\n");

        // Build the ExecStart command
        let mut exec_start = config.binary_path.clone();
        for arg in &config.args {
            exec_start.push(' ');
            exec_start.push_str(arg);
        }
        unit_content.push_str(&format!("ExecStart={}\n", exec_start));

        if let Some(working_dir) = &config.working_directory {
            unit_content.push_str(&format!("WorkingDirectory={}\n", working_dir));
        }

        // Add environment variables
        for (key, value) in &config.environment {
            unit_content.push_str(&format!("Environment=\"{}={}\"\n", key, value));
        }

        if config.auto_restart {
            unit_content.push_str("Restart=always\n");
            unit_content.push_str("RestartSec=5\n");
        }

        unit_content.push_str("\n[Install]\n");
        unit_content.push_str("WantedBy=default.target\n");

        // Write the unit file
        fs::write(&unit_path, unit_content)
            .map_err(|e| ServiceManagerError::Other(format!("Failed to write unit file: {}", e)))?;

        // Reload systemd to pick up the new unit file
        self.run_systemctl(&["daemon-reload"])?;

        Ok(())
    }
}

impl ServiceManager for SystemdServiceManager {
    fn exists(&self, service_name: &str) -> Result<bool, ServiceManagerError> {
        let unit_path = self.get_unit_file_path(service_name);
        Ok(unit_path.exists())
    }

    fn start(&self, config: &ServiceConfig) -> Result<(), ServiceManagerError> {
        let service_name = self.get_service_name(&config.name);

        // Check if service already exists and is running
        if self.exists(&config.name)? {
            match self.status(&config.name)? {
                ServiceStatus::Running => {
                    return Err(ServiceManagerError::ServiceAlreadyExists(
                        config.name.clone(),
                    ));
                }
                _ => {
                    // Service exists but not running, we can start it
                }
            }
        } else {
            // Create the unit file
            self.create_unit_file(config)?;
        }

        // Enable and start the service
        self.run_systemctl(&["enable", &service_name])
            .map_err(|e| ServiceManagerError::StartFailed(config.name.clone(), e.to_string()))?;

        self.run_systemctl(&["start", &service_name])
            .map_err(|e| ServiceManagerError::StartFailed(config.name.clone(), e.to_string()))?;

        Ok(())
    }

    fn start_existing(&self, service_name: &str) -> Result<(), ServiceManagerError> {
        let service_unit = self.get_service_name(service_name);

        // Check if unit file exists
        if !self.exists(service_name)? {
            return Err(ServiceManagerError::ServiceNotFound(
                service_name.to_string(),
            ));
        }

        // Check if already running
        match self.status(service_name)? {
            ServiceStatus::Running => {
                return Ok(()); // Already running, nothing to do
            }
            _ => {
                // Start the service
                self.run_systemctl(&["start", &service_unit]).map_err(|e| {
                    ServiceManagerError::StartFailed(service_name.to_string(), e.to_string())
                })?;
            }
        }

        Ok(())
    }

    fn start_and_confirm(
        &self,
        config: &ServiceConfig,
        timeout_secs: u64,
    ) -> Result<(), ServiceManagerError> {
        // Start the service first
        self.start(config)?;

        // Wait for confirmation with timeout
        let start_time = std::time::Instant::now();
        let timeout_duration = std::time::Duration::from_secs(timeout_secs);

        while start_time.elapsed() < timeout_duration {
            match self.status(&config.name) {
                Ok(ServiceStatus::Running) => return Ok(()),
                Ok(ServiceStatus::Failed) => {
                    return Err(ServiceManagerError::StartFailed(
                        config.name.clone(),
                        "Service failed to start".to_string(),
                    ));
                }
                Ok(_) => {
                    // Still starting, wait a bit
                    std::thread::sleep(std::time::Duration::from_millis(100));
                }
                Err(_) => {
                    // Service might not exist yet, wait a bit
                    std::thread::sleep(std::time::Duration::from_millis(100));
                }
            }
        }

        Err(ServiceManagerError::StartFailed(
            config.name.clone(),
            format!("Service did not start within {} seconds", timeout_secs),
        ))
    }

    fn start_existing_and_confirm(
        &self,
        service_name: &str,
        timeout_secs: u64,
    ) -> Result<(), ServiceManagerError> {
        // Start the existing service first
        self.start_existing(service_name)?;

        // Wait for confirmation with timeout
        let start_time = std::time::Instant::now();
        let timeout_duration = std::time::Duration::from_secs(timeout_secs);

        while start_time.elapsed() < timeout_duration {
            match self.status(service_name) {
                Ok(ServiceStatus::Running) => return Ok(()),
                Ok(ServiceStatus::Failed) => {
                    return Err(ServiceManagerError::StartFailed(
                        service_name.to_string(),
                        "Service failed to start".to_string(),
                    ));
                }
                Ok(_) => {
                    // Still starting, wait a bit
                    std::thread::sleep(std::time::Duration::from_millis(100));
                }
                Err(_) => {
                    // Service might not exist yet, wait a bit
                    std::thread::sleep(std::time::Duration::from_millis(100));
                }
            }
        }

        Err(ServiceManagerError::StartFailed(
            service_name.to_string(),
            format!("Service did not start within {} seconds", timeout_secs),
        ))
    }

    fn stop(&self, service_name: &str) -> Result<(), ServiceManagerError> {
        let service_unit = self.get_service_name(service_name);

        // Check if service exists
        if !self.exists(service_name)? {
            return Err(ServiceManagerError::ServiceNotFound(
                service_name.to_string(),
            ));
        }

        // Stop the service
        self.run_systemctl(&["stop", &service_unit]).map_err(|e| {
            ServiceManagerError::StopFailed(service_name.to_string(), e.to_string())
        })?;

        Ok(())
    }

    fn restart(&self, service_name: &str) -> Result<(), ServiceManagerError> {
        let service_unit = self.get_service_name(service_name);

        // Check if service exists
        if !self.exists(service_name)? {
            return Err(ServiceManagerError::ServiceNotFound(
                service_name.to_string(),
            ));
        }

        // Restart the service
        self.run_systemctl(&["restart", &service_unit])
            .map_err(|e| {
                ServiceManagerError::RestartFailed(service_name.to_string(), e.to_string())
            })?;

        Ok(())
    }

    fn status(&self, service_name: &str) -> Result<ServiceStatus, ServiceManagerError> {
        let service_unit = self.get_service_name(service_name);

        // Check if service exists
        if !self.exists(service_name)? {
            return Err(ServiceManagerError::ServiceNotFound(
                service_name.to_string(),
            ));
        }

        // Get service status
        let output = self
            .run_systemctl(&["is-active", &service_unit])
            .unwrap_or_else(|_| "unknown".to_string());

        let status = match output.trim() {
            "active" => ServiceStatus::Running,
            "inactive" => ServiceStatus::Stopped,
            "failed" => ServiceStatus::Failed,
            _ => ServiceStatus::Unknown,
        };

        Ok(status)
    }

    fn logs(
        &self,
        service_name: &str,
        lines: Option<usize>,
    ) -> Result<String, ServiceManagerError> {
        let service_unit = self.get_service_name(service_name);

        // Check if service exists
        if !self.exists(service_name)? {
            return Err(ServiceManagerError::ServiceNotFound(
                service_name.to_string(),
            ));
        }

        // Build journalctl command
        let mut args = vec!["--unit", &service_unit, "--no-pager"];
        let lines_arg;
        if let Some(n) = lines {
            lines_arg = format!("--lines={}", n);
            args.push(&lines_arg);
        }

        // Use journalctl to get logs
        let mut cmd = std::process::Command::new("journalctl");
        if self.user_mode {
            cmd.arg("--user");
        }
        cmd.args(&args);

        let output = cmd.output().map_err(|e| {
            ServiceManagerError::LogsFailed(
                service_name.to_string(),
                format!("Failed to run journalctl: {}", e),
            )
        })?;

        if !output.status.success() {
            let stderr = String::from_utf8_lossy(&output.stderr);
            return Err(ServiceManagerError::LogsFailed(
                service_name.to_string(),
                format!("journalctl command failed: {}", stderr),
            ));
        }

        Ok(String::from_utf8_lossy(&output.stdout).to_string())
    }

    fn list(&self) -> Result<Vec<String>, ServiceManagerError> {
        // List all services with our prefix
        let output =
            self.run_systemctl(&["list-units", "--type=service", "--all", "--no-pager"])?;

        let mut services = Vec::new();
        for line in output.lines() {
            if line.contains(&format!("{}-", self.service_prefix)) {
                // Extract service name from the line
                if let Some(unit_name) = line.split_whitespace().next() {
                    if let Some(service_name) = unit_name.strip_suffix(".service") {
                        if let Some(name) =
                            service_name.strip_prefix(&format!("{}-", self.service_prefix))
                        {
                            services.push(name.to_string());
                        }
                    }
                }
            }
        }

        Ok(services)
    }

    fn remove(&self, service_name: &str) -> Result<(), ServiceManagerError> {
        let service_unit = self.get_service_name(service_name);

        // Check if service exists
        if !self.exists(service_name)? {
            return Err(ServiceManagerError::ServiceNotFound(
                service_name.to_string(),
            ));
        }

        // Try to stop the service first, but don't fail if it's already stopped
        if let Err(e) = self.stop(service_name) {
            log::warn!(
                "Failed to stop service '{}' before removal: {}",
                service_name,
                e
            );
        }

        // Disable the service
        if let Err(e) = self.run_systemctl(&["disable", &service_unit]) {
            log::warn!("Failed to disable service '{}': {}", service_name, e);
        }

        // Remove the unit file
        let unit_path = self.get_unit_file_path(service_name);
        if unit_path.exists() {
            std::fs::remove_file(&unit_path).map_err(|e| {
                ServiceManagerError::Other(format!("Failed to remove unit file: {}", e))
            })?;
        }

        // Reload systemd to pick up the changes
        self.run_systemctl(&["daemon-reload"])?;

        Ok(())
    }
}