use std::error::Error;
use std::result::Result;
use std::time::Instant;

#[derive(Debug)]
pub struct NetworkInfo {
    pub interfaces: Option<Vec<String>>,
    pub rx_rate: Option<f64>,
    pub tx_rate: Option<f64>,
}

#[derive(Debug)]
pub struct NetworkMonitor {
    prev_rx: u64,
    prev_tx: u64,
    last_update: Instant,
}

impl Default for NetworkMonitor {
    fn default() -> Self {
        Self::new()
    }
}

impl NetworkMonitor {
    pub fn new() -> Self {
        Self {
            prev_rx: 0,
            prev_tx: 0,
            last_update: Instant::now(),
        }
    }

    pub fn update_usage(&mut self) -> Result<(f64, f64), Box<dyn Error>> {
        let (current_rx, current_tx) = get_network_bytes()?;
        let elapsed = self.last_update.elapsed().as_secs_f64();
        self.last_update = Instant::now();

        let rx_rate = if current_rx >= self.prev_rx {
            (current_rx - self.prev_rx) as f64 / elapsed
        } else {
            0.0
        };

        let tx_rate = if current_tx >= self.prev_tx {
            (current_tx - self.prev_tx) as f64 / elapsed
        } else {
            0.0
        };

        self.prev_rx = current_rx;
        self.prev_tx = current_tx;

        Ok((rx_rate, tx_rate))
    }
}

pub async fn get_network_info(monitor: &mut NetworkMonitor) -> Result<NetworkInfo, Box<dyn Error>> {
    let (rx_rate, tx_rate) = monitor.update_usage()?;
    Ok(NetworkInfo {
        interfaces: Some(get_network_interfaces()),
        rx_rate: Some(rx_rate),
        tx_rate: Some(tx_rate),
    })
}

fn get_network_bytes() -> Result<(u64, u64), Box<dyn Error>> {
    #[cfg(target_os = "windows")]
    {
        use std::ptr::null_mut;
        use winapi::shared::ifmib::MIB_IFTABLE;
        use winapi::um::iphlpapi::GetIfTable;

        unsafe {
            // Erste Abfrage zur Bestimmung der benötigten Puffergröße
            let mut buffer_size = 0u32;
            if GetIfTable(null_mut(), &mut buffer_size, 0)
                != winapi::shared::winerror::ERROR_INSUFFICIENT_BUFFER
            {
                return Err(
                    anyhow::anyhow!("Failed to get buffer size for network interfaces").into(),
                );
            }

            // Puffer allozieren
            let mut buffer = vec![0u8; buffer_size as usize];
            let if_table = buffer.as_mut_ptr() as *mut MIB_IFTABLE;

            // Tatsächliche Daten abrufen
            if GetIfTable(if_table, &mut buffer_size, 0) != 0 {
                return Err(anyhow::anyhow!("Failed to get network interface table").into());
            }

            // Daten auswerten
            let mut rx_total = 0u64;
            let mut tx_total = 0u64;

            for i in 0..(*if_table).dwNumEntries {
                let row = &*((*if_table).table.as_ptr().offset(i as isize));
                rx_total += row.dwInOctets as u64;
                tx_total += row.dwOutOctets as u64;
            }

            if rx_total == 0 && tx_total == 0 {
                Err(anyhow::anyhow!("No network data available").into())
            } else {
                Ok((rx_total, tx_total))
            }
        }
    }

    #[cfg(target_os = "linux")]
    {
        use std::fs;

        let mut rx_total = 0u64;
        let mut tx_total = 0u64;
        if let Ok(dir) = fs::read_dir("/sys/class/net") {
            for entry in dir.flatten() {
                let iface = entry.file_name();
                let iface_name = iface.to_string_lossy();

                // Ignoriere virtuelle Interfaces
                if !iface_name.starts_with("lo") && !iface_name.starts_with("virbr") {
                    if let (Ok(rx), Ok(tx)) = (
                        fs::read_to_string(entry.path().join("statistics/rx_bytes")),
                        fs::read_to_string(entry.path().join("statistics/tx_bytes")),
                    ) {
                        rx_total += rx.trim().parse::<u64>().unwrap_or(0);
                        tx_total += tx.trim().parse::<u64>().unwrap_or(0);
                    }
                }
            }
        }

        if rx_total == 0 && tx_total == 0 {
            return Err(anyhow::anyhow!("No network data available").into());
        } else {
            return Ok((rx_total, tx_total));
        }
    }

    #[cfg(not(any(target_os = "windows", target_os = "linux")))]
    Err("No network data available for this OS".into())
}

fn get_network_interfaces() -> Vec<String> {
    #[cfg(target_os = "windows")]
    {
        use std::ffi::CStr;
        use std::ptr::null_mut;
        use winapi::shared::ifmib::MIB_IFTABLE;
        use winapi::um::iphlpapi::GetIfTable;

        unsafe {
            let mut buffer_size = 0u32;
            if GetIfTable(null_mut(), &mut buffer_size, 0)
                != winapi::shared::winerror::ERROR_INSUFFICIENT_BUFFER
            {
                return vec![];
            }

            let mut buffer = vec![0u8; buffer_size as usize];
            let if_table = buffer.as_mut_ptr() as *mut MIB_IFTABLE;

            if GetIfTable(if_table, &mut buffer_size, 0) != 0 {
                return vec![];
            }

            (0..(*if_table).dwNumEntries)
                .map(|i| {
                    let row = &*((*if_table).table.as_ptr().offset(i as isize));
                    let descr = CStr::from_ptr(row.bDescr.as_ptr() as *const i8)
                        .to_string_lossy()
                        .into_owned();
                    descr.trim().to_string()
                })
                .collect()
        }
    }

    #[cfg(target_os = "linux")]
    {
        use std::fs;

        let mut interfaces = vec![];
        if let Ok(dir) = fs::read_dir("/sys/class/net") {
            for entry in dir.flatten() {
                let iface = entry.file_name();
                interfaces.push(iface.to_string_lossy().to_string());
            }
        }
        interfaces
    }

    #[cfg(not(any(target_os = "windows", target_os = "linux")))]
    vec![]
}