#![allow(dead_code)]

use crate::xx::*;
use rand::prelude::*;
use std::time::{Duration, SystemTime, UNIX_EPOCH};

pub fn get_timestamp() -> u64 {
    match SystemTime::now().duration_since(UNIX_EPOCH) {
        Ok(n) => n.as_micros() as u64,
        Err(_) => panic!("SystemTime before UNIX_EPOCH!"),
    }
}

pub fn get_timestamp_string() -> String {
    let dt = chrono::Utc::now();
    dt.time().format("%H:%M:%S.3f").to_string()
}

pub fn random_bytes(dest: &mut [u8]) -> Result<(), String> {
    let mut rng = rand::thread_rng();
    rng.try_fill_bytes(dest).map_err(|err| format!("{:?}", err))
}

pub fn get_random_u32() -> u32 {
    let mut rng = rand::thread_rng();
    rng.next_u32()
}

pub fn get_random_u64() -> u64 {
    let mut rng = rand::thread_rng();
    rng.next_u64()
}

pub async fn sleep(millis: u32) {
    if millis == 0 {
        cfg_if! {
            if #[cfg(feature="rt-async-std")] {
                async_std::task::yield_now().await;
            } else if #[cfg(feature="rt-tokio")] {
                tokio::task::yield_now().await;
            }
        }
    } else {
        cfg_if! {
            if #[cfg(feature="rt-async-std")] {
                async_std::task::sleep(Duration::from_millis(u64::from(millis))).await;
            } else if #[cfg(feature="rt-tokio")] {
                tokio::time::sleep(Duration::from_millis(u64::from(millis))).await;
            }
        }
    }
}

pub fn system_boxed<'a, Out>(
    future: impl Future<Output = Out> + Send + 'a,
) -> SystemPinBoxFutureLifetime<'a, Out> {
    Box::pin(future)
}

pub fn spawn<Out>(future: impl Future<Output = Out> + Send + 'static) -> MustJoinHandle<Out>
where
    Out: Send + 'static,
{
    cfg_if! {
        if #[cfg(feature="rt-async-std")] {
            MustJoinHandle::new(async_std::task::spawn(future))
        } else if #[cfg(feature="rt-tokio")] {
            MustJoinHandle::new(tokio::task::spawn(future))
        }
    }
}

pub fn spawn_local<Out>(future: impl Future<Output = Out> + 'static) -> MustJoinHandle<Out>
where
    Out: 'static,
{
    cfg_if! {
        if #[cfg(feature="rt-async-std")] {
            MustJoinHandle::new(async_std::task::spawn_local(future))
        } else if #[cfg(feature="rt-tokio")] {
            MustJoinHandle::new(tokio::task::spawn_local(future))
        }
    }
}

pub fn spawn_with_local_set<Out>(
    future: impl Future<Output = Out> + Send + 'static,
) -> MustJoinHandle<Out>
where
    Out: Send + 'static,
{
    cfg_if! {
        if #[cfg(feature="rt-async-std")] {
            spawn(future)
        } else if #[cfg(feature="rt-tokio")] {
            MustJoinHandle::new(tokio::task::spawn_blocking(move || {
                let rt = tokio::runtime::Handle::current();
                rt.block_on(async {
                    let local = tokio::task::LocalSet::new();
                    local.run_until(future).await
                })
            }))
        }
    }
}

pub fn spawn_detached<Out>(future: impl Future<Output = Out> + Send + 'static)
where
    Out: Send + 'static,
{
    cfg_if! {
        if #[cfg(feature="rt-async-std")] {
            drop(async_std::task::spawn(future));
        } else if #[cfg(feature="rt-tokio")] {
            drop(tokio::task::spawn(future));
        }
    }
}

pub fn interval<F, FUT>(freq_ms: u32, callback: F) -> SystemPinBoxFuture<()>
where
    F: Fn() -> FUT + Send + Sync + 'static,
    FUT: Future<Output = ()> + Send,
{
    let e = Eventual::new();

    let ie = e.clone();
    let jh = spawn(async move {
        while timeout(freq_ms, ie.instance_clone(())).await.is_err() {
            callback().await;
        }
    });

    Box::pin(async move {
        e.resolve().await;
        jh.await;
    })
}

cfg_if! {
    if #[cfg(feature="rt-async-std")] {
        pub use async_std::future::TimeoutError;
    } else if #[cfg(feature="rt-tokio")] {
        pub use tokio::time::error::Elapsed as TimeoutError;
    }
}

pub async fn timeout<F, T>(dur_ms: u32, f: F) -> Result<T, TimeoutError>
where
    F: Future<Output = T>,
{
    cfg_if! {
        if #[cfg(feature="rt-async-std")] {
            async_std::future::timeout(Duration::from_millis(dur_ms as u64), f).await
        } else if #[cfg(feature="rt-tokio")] {
            tokio::time::timeout(Duration::from_millis(dur_ms as u64), f).await
        }
    }
}

pub fn get_concurrency() -> u32 {
    std::thread::available_parallelism()
        .map(|x| x.get())
        .unwrap_or_else(|e| {
            warn!("unable to get concurrency defaulting to single core: {}", e);
            1
        }) as u32
}

pub async fn get_outbound_relay_peer() -> Option<crate::veilid_api::PeerInfo> {
    panic!("Native Veilid should never require an outbound relay");
}

/*
pub fn async_callback<F, OF, EF, T, E>(fut: F, ok_fn: OF, err_fn: EF)
where
    F: Future<Output = Result<T, E>> + Send + 'static,
    OF: FnOnce(T) + Send + 'static,
    EF: FnOnce(E) + Send + 'static,
{
    spawn(Box::pin(async move {
        match fut.await {
            Ok(v) => ok_fn(v),
            Err(e) => err_fn(e),
        };
    }));
}
*/

/////////////////////////////////////////////////////////////////////////////////
// Resolver
//
// Uses system resolver on windows and trust-dns-resolver elsewhere
// trust-dns-resolver hangs for a long time on Windows building some cache or something
// and we really should be using the built-in system resolver when possible

cfg_if! {
    if #[cfg(not(target_os = "windows"))] {
        cfg_if! {
            if #[cfg(feature="rt-async-std")] {
                use async_std_resolver::{config, resolver, resolver_from_system_conf, AsyncStdResolver as AsyncResolver};
            } else if #[cfg(feature="rt-tokio")] {
                use trust_dns_resolver::{config, TokioAsyncResolver as AsyncResolver, error::ResolveError};

                pub async fn resolver(
                    config: config::ResolverConfig,
                    options: config::ResolverOpts,
                ) -> Result<AsyncResolver, ResolveError> {
                    AsyncResolver::tokio(config, options)
                }

                /// Constructs a new async-std based Resolver with the system configuration.
                ///
                /// This will use `/etc/resolv.conf` on Unix OSes and the registry on Windows.
                #[cfg(any(unix, target_os = "windows"))]
                pub async fn resolver_from_system_conf() -> Result<AsyncResolver, ResolveError> {
                    AsyncResolver::tokio_from_system_conf()
                }
            }
        }


        lazy_static::lazy_static! {
            static ref RESOLVER: Arc<AsyncMutex<Option<AsyncResolver>>> = Arc::new(AsyncMutex::new(None));
        }
    }
}

cfg_if! {
    if #[cfg(not(target_os = "windows"))] {
        async fn get_resolver() -> Result<AsyncResolver, String> {
            let mut resolver_lock = RESOLVER.lock().await;
            if let Some(r) = &*resolver_lock {
                Ok(r.clone())
            } else {
                let resolver = match resolver_from_system_conf().await {
                    Ok(v) => v,
                    Err(_) => resolver(
                        config::ResolverConfig::default(),
                        config::ResolverOpts::default(),
                    )
                    .await
                    .expect("failed to connect resolver"),
                };

                *resolver_lock = Some(resolver.clone());
                Ok(resolver)
            }
        }
    }
}

pub async fn txt_lookup<S: AsRef<str>>(host: S) -> Result<Vec<String>, String> {
    cfg_if! {
        if #[cfg(target_os = "windows")] {
            use core::ffi::c_void;
            use windows::core::PSTR;
            use std::ffi::CStr;
            use windows::Win32::NetworkManagement::Dns::{DnsQuery_UTF8, DnsFree, DNS_TYPE_TEXT, DNS_QUERY_STANDARD, DNS_RECORDA, DnsFreeRecordList};

            let mut out = Vec::new();
            unsafe {
                let mut p_query_results: *mut DNS_RECORDA = core::ptr::null_mut();
                let status = DnsQuery_UTF8(host.as_ref(), DNS_TYPE_TEXT as u16, DNS_QUERY_STANDARD, core::ptr::null_mut(), &mut p_query_results as *mut *mut DNS_RECORDA, core::ptr::null_mut());
                if status != 0 {
                    return Err("Failed to resolve TXT record".to_owned());
                }

                let mut p_record: *mut DNS_RECORDA = p_query_results;
                while !p_record.is_null() {
                    if (*p_record).wType == DNS_TYPE_TEXT as u16 {
                        let count:usize = (*p_record).Data.TXT.dwStringCount.try_into().unwrap();
                        let string_array: *const PSTR = &(*p_record).Data.TXT.pStringArray[0];
                        for n in 0..count {
                            let pstr: PSTR = *(string_array.add(n));
                            let c_str: &CStr = CStr::from_ptr(pstr.0 as *const i8);
                            if let Ok(str_slice) = c_str.to_str() {
                                let str_buf: String = str_slice.to_owned();
                                out.push(str_buf);
                            }
                        }
                    }
                    p_record = (*p_record).pNext;
                }
                DnsFree(p_query_results as *const c_void, DnsFreeRecordList);
            }
            Ok(out)

        } else {
            let resolver = get_resolver().await?;
            let txt_result = resolver
                .txt_lookup(host.as_ref())
                .await
                .map_err(|e| e.to_string())?;
            let mut out = Vec::new();
            for x in txt_result.iter() {
                for s in x.txt_data() {
                    out.push(String::from_utf8(s.to_vec()).map_err(|e| e.to_string())?);
                }
            }
            Ok(out)
        }
    }
}

pub async fn ptr_lookup(ip_addr: IpAddr) -> Result<String, String> {
    cfg_if! {
        if #[cfg(target_os = "windows")] {
            use core::ffi::c_void;
            use windows::core::PSTR;
            use std::ffi::CStr;
            use windows::Win32::NetworkManagement::Dns::{DnsQuery_UTF8, DnsFree, DNS_TYPE_PTR, DNS_QUERY_STANDARD, DNS_RECORDA, DnsFreeRecordList};

            let host = match ip_addr {
                IpAddr::V4(a) => {
                    let oct = a.octets();
                    format!("{}.{}.{}.{}.in-addr.arpa",oct[3],oct[2],oct[1],oct[0])
                }
                IpAddr::V6(a) => {
                    let mut s = String::new();
                    for b in hex::encode(a.octets()).as_bytes().iter().rev() {
                        s.push_str(&format!("{}.",b));
                    }
                    format!("{}ip6.arpa",s)
                }
            };

            unsafe {
                let mut p_query_results: *mut DNS_RECORDA = core::ptr::null_mut();
                let status = DnsQuery_UTF8(host, DNS_TYPE_PTR as u16, DNS_QUERY_STANDARD, core::ptr::null_mut(), &mut p_query_results as *mut *mut DNS_RECORDA, core::ptr::null_mut());
                if status != 0 {
                    return Err("Failed to resolve PTR record".to_owned());
                }

                let mut p_record: *mut DNS_RECORDA = p_query_results;
                while !p_record.is_null() {
                    if (*p_record).wType == DNS_TYPE_PTR as u16 {
                        let p_name_host: PSTR = (*p_record).Data.PTR.pNameHost;
                        let c_str: &CStr = CStr::from_ptr(p_name_host.0 as *const i8);
                        if let Ok(str_slice) = c_str.to_str() {
                            let str_buf: String = str_slice.to_owned();
                            return Ok(str_buf);
                        }
                    }
                    p_record = (*p_record).pNext;
                }
                DnsFree(p_query_results as *const c_void, DnsFreeRecordList);
            }
            return Err("No records returned".to_owned());
        } else {
            let resolver = get_resolver().await?;
            let ptr_result = resolver
                .reverse_lookup(ip_addr)
                .await
                .map_err(|e| e.to_string())?;
            if let Some(r) = ptr_result.iter().next() {
                Ok(r.to_string().trim_end_matches('.').to_string())
            } else {
                Err("PTR lookup returned an empty string".to_owned())
            }
        }
    }
}