/// Módulo para descubrir servicios systemd existentes
use std::fs;
use std::path::Path;
use crate::logger::get_logger;
use crate::config::{get_config_manager, MonitoredApp};

const SYSTEMD_DIR: &str = "/etc/systemd/system";
const SERVICE_PREFIX: &str = "siax-app-";

/// Descubre servicios systemd existentes con prefijo siax-app-*
pub fn discover_services() -> Vec<DiscoveredService> {
    let logger = get_logger();
    logger.info("Discovery", &format!("🔍 Escaneando servicios systemd en: {}", SYSTEMD_DIR));
    println!("🔍 Discovery: Buscando servicios en {}", SYSTEMD_DIR);

    let mut services = Vec::new();

    // Leer directorio de systemd
    let entries = match fs::read_dir(SYSTEMD_DIR) {
        Ok(entries) => {
            logger.info("Discovery", &format!("✅ Directorio {} accesible", SYSTEMD_DIR));
            println!("✅ Discovery: Directorio {} accesible", SYSTEMD_DIR);
            entries
        },
        Err(e) => {
            logger.error("Discovery", &format!("❌ No se pudo leer directorio {}", SYSTEMD_DIR), Some(&e.to_string()));
            println!("❌ Discovery: ERROR - No se pudo leer {}: {}", SYSTEMD_DIR, e);
            return services;
        }
    };

    // Buscar archivos siax-app-*.service
    let mut total_files = 0;
    let mut siax_files = 0;

    for entry in entries.flatten() {
        total_files += 1;
        let path = entry.path();
        if let Some(filename) = path.file_name() {
            let filename_str = filename.to_string_lossy();

            // Verificar que sea un archivo .service con nuestro prefijo
            if filename_str.starts_with(SERVICE_PREFIX) && filename_str.ends_with(".service") {
                siax_files += 1;
                logger.info("Discovery", &format!("✅ Encontrado: {}", filename_str));
                println!("✅ Discovery: Servicio detectado: {}", filename_str);

                // Extraer nombre de la app
                let app_name = extract_app_name(&filename_str);

                // Leer configuración del servicio
                if let Some(service) = parse_service_file(&path, &app_name) {
                    services.push(service);
                } else {
                    logger.warning("Discovery", &format!("⚠️  No se pudo parsear: {}", filename_str), None);
                    println!("⚠️  Discovery: No se pudo parsear {}", filename_str);
                }
            }
        }
    }

    logger.info("Discovery", &format!("📊 Escaneados {} archivos, {} con prefijo '{}', {} parseados exitosamente",
        total_files, siax_files, SERVICE_PREFIX, services.len()));
    println!("📊 Discovery: Archivos totales: {}, siax-app-*: {}, parseados: {}",
        total_files, siax_files, services.len());

    services
}

/// Extrae el nombre de la app desde el nombre del archivo
/// Ejemplo: "siax-app-IDEAS.service" -> "app_IDEAS"
fn extract_app_name(filename: &str) -> String {
    // Remover "siax-app-" del inicio y ".service" del final
    filename
        .trim_start_matches(SERVICE_PREFIX)
        .trim_end_matches(".service")
        .to_string()
}

/// Servicio descubierto en systemd
#[derive(Debug, Clone)]
pub struct DiscoveredService {
    pub app_name: String,
    pub service_file: String,
    pub working_directory: Option<String>,
    pub user: Option<String>,
    pub exec_start: Option<String>,
    pub port: Option<i32>,
    pub node_env: String,
    pub entry_point: Option<String>,
    pub node_bin: Option<String>,
}

/// Parsea un archivo .service para extraer configuración completa
fn parse_service_file(path: &Path, app_name: &str) -> Option<DiscoveredService> {
    let logger = get_logger();

    let content = match fs::read_to_string(path) {
        Ok(content) => content,
        Err(e) => {
            logger.error("Discovery", &format!("Error leyendo {}", path.display()), Some(&e.to_string()));
            return None;
        }
    };

    let mut service = DiscoveredService {
        app_name: app_name.to_string(),
        service_file: path.to_string_lossy().to_string(),
        working_directory: None,
        user: None,
        exec_start: None,
        port: None,
        node_env: String::from("production"),
        entry_point: None,
        node_bin: None,
    };

    // Parsear líneas del archivo
    for line in content.lines() {
        let line = line.trim();

        // WorkingDirectory
        if line.starts_with("WorkingDirectory=") {
            service.working_directory = Some(line.trim_start_matches("WorkingDirectory=").to_string());
        }

        // User
        if line.starts_with("User=") {
            service.user = Some(line.trim_start_matches("User=").to_string());
        }

        // ExecStart
        if line.starts_with("ExecStart=") {
            let exec_start = line.trim_start_matches("ExecStart=").to_string();

            // Extraer node_bin y entry_point del ExecStart
            // Ejemplo: /home/user/.nvm/versions/node/v24.12.0/bin/node server.js
            let parts: Vec<&str> = exec_start.split_whitespace().collect();
            if !parts.is_empty() {
                service.node_bin = Some(parts[0].to_string());

                // Buscar el archivo .js como entry_point
                for part in &parts[1..] {
                    if part.ends_with(".js") {
                        service.entry_point = Some(part.to_string());
                        break;
                    }
                }
            }

            service.exec_start = Some(exec_start);
        }

        // Environment con PORT
        if line.starts_with("Environment=") && line.contains("PORT") {
            if let Some(port) = extract_port_from_env(line) {
                service.port = Some(port);
            }
        }

        // Environment con NODE_ENV
        if line.starts_with("Environment=") && line.contains("NODE_ENV") {
            if let Some(env) = extract_env_value(line, "NODE_ENV") {
                service.node_env = env;
            }
        }
    }

    logger.info("Discovery", &format!("  App: {}, User: {:?}, WorkDir: {:?}, Env: {}, EntryPoint: {:?}",
        service.app_name,
        service.user,
        service.working_directory,
        service.node_env,
        service.entry_point
    ));

    Some(service)
}

/// Extrae el puerto de una línea Environment
/// Ejemplo: Environment="PORT=3000" -> Some(3000)
fn extract_port_from_env(line: &str) -> Option<i32> {
    // Buscar PORT=número
    if let Some(start) = line.find("PORT=") {
        let after_port = &line[start + 5..];
        // Extraer números
        let port_str: String = after_port.chars()
            .take_while(|c| c.is_numeric())
            .collect();

        port_str.parse::<i32>().ok()
    } else {
        None
    }
}

/// Extrae un valor de variable de entorno de una línea Environment
/// Ejemplo: Environment="NODE_ENV=production" -> Some("production")
fn extract_env_value(line: &str, var_name: &str) -> Option<String> {
    let pattern = format!("{}=", var_name);
    if let Some(start) = line.find(&pattern) {
        let after_var = &line[start + pattern.len()..];
        // Extraer hasta espacios, comillas o fin de línea
        let value: String = after_var.chars()
            .take_while(|c| !c.is_whitespace() && *c != '"')
            .collect();

        if !value.is_empty() {
            Some(value)
        } else {
            None
        }
    } else {
        None
    }
}

/// Sincroniza los servicios descubiertos con monitored_apps.json
pub fn sync_discovered_services(services: Vec<DiscoveredService>) {
    let logger = get_logger();
    let config_manager = get_config_manager();

    logger.info("Discovery", &format!("🔄 Sincronizando {} servicios descubiertos...", services.len()));
    println!("🔄 Discovery: Sincronizando {} servicios con monitored_apps.json", services.len());

    let mut added_count = 0;
    let mut skipped_count = 0;

    for service in services {
        // Intentar detectar el puerto si no se encontró en Environment
        let port = service.port.unwrap_or_else(|| {
            detect_port_from_name(&service.app_name)
        });

        // Verificar si ya existe en la configuración
        let existing_apps = config_manager.get_apps();
        let already_exists = existing_apps.iter().any(|app| app.name == service.app_name);

        if already_exists {
            logger.info("Discovery", &format!("⏭️  {} ya existe en configuración", service.app_name));
            println!("⏭️  Discovery: {} ya existe, omitiendo", service.app_name);
            skipped_count += 1;
            continue;
        }

        // Crear MonitoredApp con información completa
        let service_name = format!("siax-app-{}.service", service.app_name);
        let registered_at = chrono::Local::now().to_rfc3339();

        let app = MonitoredApp {
            name: service.app_name.clone(),
            service_name,
            path: service.working_directory.unwrap_or_default(),
            port,
            entry_point: service.entry_point.unwrap_or_default(),
            node_bin: service.node_bin.unwrap_or_default(),
            mode: service.node_env,
            service_file_path: service.service_file.clone(),
            registered_at,
            systemd_service: None,
            created_at: None,
        };

        // Agregar a monitored_apps.json
        logger.info("Discovery", &format!("➕ Agregando {} (puerto: {}, entry: {})",
            app.name, app.port, app.entry_point));

        match config_manager.add_app_full(app) {
            Ok(_) => {
                logger.info("Discovery", &format!("✅ {} agregado exitosamente", service.app_name));
                println!("✅ Discovery: {} agregado a monitored_apps.json", service.app_name);
                added_count += 1;
            }
            Err(e) => {
                logger.error("Discovery", &format!("Error agregando {}", service.app_name), Some(&e));
                println!("❌ Discovery: Error agregando {}: {}", service.app_name, e);
            }
        }
    }

    logger.info("Discovery", &format!("📊 Resumen: {} agregadas, {} ya existían", added_count, skipped_count));
    println!("📊 Discovery: Resumen final - {} apps nuevas, {} existentes", added_count, skipped_count);
}

/// Intenta detectar el puerto desde el nombre de la app
/// Esto es un fallback simple si no se encuentra en el .service
fn detect_port_from_name(app_name: &str) -> i32 {
    // Algunos puertos conocidos por nombre
    match app_name.to_lowercase().as_str() {
        name if name.contains("tareas") => 3000,
        name if name.contains("fidelizacion") => 3001,
        name if name.contains("ideas") => 2000,
        _ => 8080, // Puerto por defecto genérico
    }
}

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

    #[test]
    fn test_extract_app_name() {
        assert_eq!(extract_app_name("siax-app-IDEAS.service"), "IDEAS");
        assert_eq!(extract_app_name("siax-app-TAREAS.service"), "TAREAS");
        assert_eq!(extract_app_name("siax-app-fidelizacion.service"), "fidelizacion");
    }

    #[test]
    fn test_extract_port_from_env() {
        assert_eq!(extract_port_from_env("Environment=PORT=3000"), Some(3000));
        assert_eq!(extract_port_from_env("Environment=\"PORT=8080\""), Some(8080));
        assert_eq!(extract_port_from_env("Environment=NODE_ENV=production"), None);
    }

    #[test]
    fn test_detect_port_from_name() {
        assert_eq!(detect_port_from_name("app_tareas"), 3000);
        assert_eq!(detect_port_from_name("IDEAS"), 2000);
        assert_eq!(detect_port_from_name("unknown_app"), 8080);
    }
}