// Take a look at the license at the top of the repository in the LICENSE file.

use crate::{NetworkExt, NetworksExt, NetworksIter};

use std::collections::{hash_map, HashMap};

use winapi::shared::ifdef::{MediaConnectStateDisconnected, NET_LUID};
use winapi::shared::netioapi::{
    FreeMibTable, GetIfEntry2, GetIfTable2, MIB_IF_ROW2, PMIB_IF_TABLE2,
};
use winapi::shared::winerror::NO_ERROR;

macro_rules! old_and_new {
    ($ty_:expr, $name:ident, $old:ident, $new_val:expr) => {{
        $ty_.$old = $ty_.$name;
        $ty_.$name = $new_val;
    }};
}

#[doc = include_str!("../../md_doc/networks.md")]
pub struct Networks {
    interfaces: HashMap<String, NetworkData>,
}

impl Networks {
    pub(crate) fn new() -> Networks {
        Networks {
            interfaces: HashMap::new(),
        }
    }
}

impl NetworksExt for Networks {
    #[allow(clippy::needless_lifetimes)]
    fn iter<'a>(&'a self) -> NetworksIter<'a> {
        NetworksIter::new(self.interfaces.iter())
    }

    fn refresh_networks_list(&mut self) {
        let mut table: PMIB_IF_TABLE2 = std::ptr::null_mut();

        unsafe {
            if GetIfTable2(&mut table) != NO_ERROR {
                return;
            }

            for (_, data) in self.interfaces.iter_mut() {
                data.updated = false;
            }

            // In here, this is tricky: we have to filter out the software interfaces to only keep
            // the hardware ones. To do so, we first check the connection potential speed (if 0, not
            // interesting), then we check its state: if not open, not interesting either. And finally,
            // we count the members of a same group: if there is more than 1, then it's software level.
            let mut groups = HashMap::new();
            let mut indexes = Vec::new();
            let ptr = (*table).Table.as_ptr();
            for i in 0..(*table).NumEntries {
                let ptr = &*ptr.offset(i as _);
                if (ptr.TransmitLinkSpeed == 0 && ptr.ReceiveLinkSpeed == 0)
                    || ptr.MediaConnectState == MediaConnectStateDisconnected
                    || ptr.PhysicalAddressLength == 0
                {
                    continue;
                }
                let id = vec![
                    ptr.InterfaceGuid.Data2,
                    ptr.InterfaceGuid.Data3,
                    ptr.InterfaceGuid.Data4[0] as _,
                    ptr.InterfaceGuid.Data4[1] as _,
                    ptr.InterfaceGuid.Data4[2] as _,
                    ptr.InterfaceGuid.Data4[3] as _,
                    ptr.InterfaceGuid.Data4[4] as _,
                    ptr.InterfaceGuid.Data4[5] as _,
                    ptr.InterfaceGuid.Data4[6] as _,
                    ptr.InterfaceGuid.Data4[7] as _,
                ];
                let entry = groups.entry(id.clone()).or_insert(0);
                *entry += 1;
                if *entry > 1 {
                    continue;
                }
                indexes.push((i, id));
            }
            for (i, id) in indexes {
                let ptr = &*ptr.offset(i as _);
                if *groups.get(&id).unwrap_or(&0) > 1 {
                    continue;
                }
                let mut pos = 0;
                for x in ptr.Alias.iter() {
                    if *x == 0 {
                        break;
                    }
                    pos += 1;
                }
                let interface_name = match String::from_utf16(&ptr.Alias[..pos]) {
                    Ok(s) => s,
                    _ => continue,
                };
                match self.interfaces.entry(interface_name) {
                    hash_map::Entry::Occupied(mut e) => {
                        let mut interface = e.get_mut();
                        old_and_new!(interface, current_out, old_out, ptr.OutOctets);
                        old_and_new!(interface, current_in, old_in, ptr.InOctets);
                        old_and_new!(
                            interface,
                            packets_in,
                            old_packets_in,
                            ptr.InUcastPkts.saturating_add(ptr.InNUcastPkts)
                        );
                        old_and_new!(
                            interface,
                            packets_out,
                            old_packets_out,
                            ptr.OutUcastPkts.saturating_add(ptr.OutNUcastPkts)
                        );
                        old_and_new!(interface, errors_in, old_errors_in, ptr.InErrors);
                        old_and_new!(interface, errors_out, old_errors_out, ptr.OutErrors);
                        interface.updated = true;
                    }
                    hash_map::Entry::Vacant(e) => {
                        let packets_in = ptr.InUcastPkts.saturating_add(ptr.InNUcastPkts);
                        let packets_out = ptr.OutUcastPkts.saturating_add(ptr.OutNUcastPkts);

                        e.insert(NetworkData {
                            id: ptr.InterfaceLuid,
                            current_out: ptr.OutOctets,
                            old_out: ptr.OutOctets,
                            current_in: ptr.InOctets,
                            old_in: ptr.InOctets,
                            packets_in,
                            old_packets_in: packets_in,
                            packets_out,
                            old_packets_out: packets_out,
                            errors_in: ptr.InErrors,
                            old_errors_in: ptr.InErrors,
                            errors_out: ptr.OutErrors,
                            old_errors_out: ptr.OutErrors,
                            updated: true,
                        });
                    }
                }
            }
            FreeMibTable(table as _);
        }
        // Remove interfaces which are gone.
        self.interfaces.retain(|_, d| d.updated);
    }

    fn refresh(&mut self) {
        let entry = std::mem::MaybeUninit::<MIB_IF_ROW2>::zeroed();

        unsafe {
            let mut entry = entry.assume_init();
            for (_, interface) in self.interfaces.iter_mut() {
                entry.InterfaceLuid = interface.id;
                entry.InterfaceIndex = 0; // to prevent the function to pick this one as index
                if GetIfEntry2(&mut entry) != NO_ERROR {
                    continue;
                }
                old_and_new!(interface, current_out, old_out, entry.OutOctets);
                old_and_new!(interface, current_in, old_in, entry.InOctets);
                old_and_new!(
                    interface,
                    packets_in,
                    old_packets_in,
                    entry.InUcastPkts.saturating_add(entry.InNUcastPkts)
                );
                old_and_new!(
                    interface,
                    packets_out,
                    old_packets_out,
                    entry.OutUcastPkts.saturating_add(entry.OutNUcastPkts)
                );
                old_and_new!(interface, errors_in, old_errors_in, entry.InErrors);
                old_and_new!(interface, errors_out, old_errors_out, entry.OutErrors);
            }
        }
    }
}

#[doc = include_str!("../../md_doc/network_data.md")]
pub struct NetworkData {
    id: NET_LUID,
    current_out: u64,
    old_out: u64,
    current_in: u64,
    old_in: u64,
    packets_in: u64,
    old_packets_in: u64,
    packets_out: u64,
    old_packets_out: u64,
    errors_in: u64,
    old_errors_in: u64,
    errors_out: u64,
    old_errors_out: u64,
    updated: bool,
}

impl NetworkExt for NetworkData {
    fn received(&self) -> u64 {
        self.current_in.saturating_sub(self.old_in)
    }

    fn total_received(&self) -> u64 {
        self.current_in
    }

    fn transmitted(&self) -> u64 {
        self.current_out.saturating_sub(self.old_out)
    }

    fn total_transmitted(&self) -> u64 {
        self.current_out
    }

    fn packets_received(&self) -> u64 {
        self.packets_in.saturating_sub(self.old_packets_in)
    }

    fn total_packets_received(&self) -> u64 {
        self.packets_in
    }

    fn packets_transmitted(&self) -> u64 {
        self.packets_out.saturating_sub(self.old_packets_out)
    }

    fn total_packets_transmitted(&self) -> u64 {
        self.packets_out
    }

    fn errors_on_received(&self) -> u64 {
        self.errors_in.saturating_sub(self.old_errors_in)
    }

    fn total_errors_on_received(&self) -> u64 {
        self.errors_in
    }

    fn errors_on_transmitted(&self) -> u64 {
        self.errors_out.saturating_sub(self.old_errors_out)
    }

    fn total_errors_on_transmitted(&self) -> u64 {
        self.errors_out
    }
}
