c-ares 13.0.0

use core::ffi::c_int;
use std::fmt;
use std::ptr;

use itertools::Itertools;

use crate::error::{Error, Result};
use crate::record::QueryRecord;
use crate::types::QueryType;
use crate::utils::hostname_as_str;

/// The result of a successful SRV lookup.
#[derive(Debug)]
pub struct SRVResults {
    srv_reply: *mut c_ares_sys::ares_srv_reply,
}

/// The contents of a single SRV record.
#[derive(Clone, Copy)]
pub struct SRVResult<'a> {
    // A single result - reference into an `SRVResults`.
    srv_reply: &'a c_ares_sys::ares_srv_reply,
}

impl SRVResults {
    /// Obtain an `SRVResults` from the response to an SRV lookup.
    pub fn parse_from(data: &[u8]) -> Result<SRVResults> {
        let mut srv_reply: *mut c_ares_sys::ares_srv_reply = ptr::null_mut();
        let parse_status = unsafe {
            c_ares_sys::ares_parse_srv_reply(data.as_ptr(), data.len() as c_int, &raw mut srv_reply)
        };
        if parse_status == c_ares_sys::ares_status_t::ARES_SUCCESS as i32 {
            let srv_result = SRVResults::new(srv_reply);
            Ok(srv_result)
        } else {
            Err(Error::from(parse_status))
        }
    }

    fn new(srv_reply: *mut c_ares_sys::ares_srv_reply) -> Self {
        SRVResults { srv_reply }
    }

    /// Returns an iterator over the `SRVResult` values in this `SRVResults`.
    pub fn iter(&self) -> SRVResultsIter<'_> {
        SRVResultsIter {
            next: unsafe { self.srv_reply.as_ref() },
        }
    }
}

impl fmt::Display for SRVResults {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        let results = self.iter().format("}, {");
        write!(fmt, "[{{{results}}}]")
    }
}

/// Iterator of `SRVResult`s.
#[derive(Clone, Debug)]
pub struct SRVResultsIter<'a> {
    next: Option<&'a c_ares_sys::ares_srv_reply>,
}

impl<'a> Iterator for SRVResultsIter<'a> {
    type Item = SRVResult<'a>;
    fn next(&mut self) -> Option<Self::Item> {
        let opt_reply = self.next;
        self.next = opt_reply.and_then(|reply| unsafe { reply.next.as_ref() });
        opt_reply.map(|reply| SRVResult { srv_reply: reply })
    }
}

impl<'a> IntoIterator for &'a SRVResults {
    type Item = SRVResult<'a>;
    type IntoIter = SRVResultsIter<'a>;

    fn into_iter(self) -> Self::IntoIter {
        self.iter()
    }
}

impl std::iter::FusedIterator for SRVResultsIter<'_> {}

impl Drop for SRVResults {
    fn drop(&mut self) {
        unsafe { c_ares_sys::ares_free_data(self.srv_reply.cast()) }
    }
}

unsafe impl Send for SRVResults {}
unsafe impl Sync for SRVResults {}
unsafe impl Send for SRVResult<'_> {}
unsafe impl Sync for SRVResult<'_> {}
unsafe impl Send for SRVResultsIter<'_> {}
unsafe impl Sync for SRVResultsIter<'_> {}

impl fmt::Debug for SRVResult<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SRVResult")
            .field("host", &self.host())
            .field("port", &self.port())
            .field("priority", &self.priority())
            .field("weight", &self.weight())
            .finish()
    }
}

impl<'a> SRVResult<'a> {
    /// Returns the hostname in this `SRVResult`.
    pub fn host(self) -> &'a str {
        unsafe { hostname_as_str(self.srv_reply.host) }
    }

    /// Returns the weight in this `SRVResult`.
    pub fn weight(self) -> u16 {
        self.srv_reply.weight
    }

    /// Returns the priority in this `SRVResult`.
    pub fn priority(self) -> u16 {
        self.srv_reply.priority
    }

    /// Returns the port in this `SRVResult`.
    pub fn port(self) -> u16 {
        self.srv_reply.port
    }
}

impl fmt::Display for SRVResult<'_> {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        write!(fmt, "Host: {}, ", self.host())?;
        write!(fmt, "Port: {}, ", self.port())?;
        write!(fmt, "Priority: {}, ", self.priority())?;
        write!(fmt, "Weight: {}", self.weight())
    }
}

impl QueryRecord for SRVResults {
    const QUERY_TYPE: QueryType = QueryType::SRV;
    fn parse(data: &[u8]) -> Result<Self> {
        Self::parse_from(data)
    }
}

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

    #[test]
    fn parse_invalid_data() {
        let result = SRVResults::parse_from(&[]);
        assert!(result.is_err());
    }

    #[test]
    fn is_send() {
        fn assert_send<T: Send>() {}
        assert_send::<SRVResult>();
        assert_send::<SRVResults>();
        assert_send::<SRVResultsIter>();
    }

    #[test]
    fn is_sync() {
        fn assert_sync<T: Sync>() {}
        assert_sync::<SRVResult>();
        assert_sync::<SRVResults>();
        assert_sync::<SRVResultsIter>();
    }

    // DNS SRV response: _sip._tcp.example.com -> sip.example.com, priority 10, weight 60, port 5060
    const ONE_SRV_RECORD: &[u8] = &[
        0x00, 0x00, 0x81, 0x80, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x04, 0x5f, 0x73,
        0x69, 0x70, 0x04, 0x5f, 0x74, 0x63, 0x70, 0x07, 0x65, 0x78, 0x61, 0x6d, 0x70, 0x6c, 0x65,
        0x03, 0x63, 0x6f, 0x6d, 0x00, 0x00, 0x21, 0x00, 0x01, 0xc0, 0x0c, 0x00, 0x21, 0x00, 0x01,
        0x00, 0x00, 0x01, 0x2c, 0x00, 0x17, 0x00, 0x0a, 0x00, 0x3c, 0x13, 0xc4, 0x03, 0x73, 0x69,
        0x70, 0x07, 0x65, 0x78, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x03, 0x63, 0x6f, 0x6d, 0x00,
    ];

    #[test]
    fn debug_srv_result() {
        let results = SRVResults::parse_from(ONE_SRV_RECORD).unwrap();
        let result = results.iter().next().unwrap();
        let debug = format!("{result:?}");
        assert!(debug.contains("SRVResult"));
        assert!(debug.contains("sip.example.com"));
        assert!(debug.contains("5060"));
        assert!(debug.contains("60"));
    }

    #[test]
    fn debug_srv_results_iter() {
        let results = SRVResults::parse_from(ONE_SRV_RECORD).unwrap();
        let iter = results.iter();
        let debug = format!("{iter:?}");
        assert!(debug.contains("SRVResultsIter"));
    }
}