use std::{
	io,
	os::raw::{
		c_char,
		c_void,
	},
	pin::Pin,
	task::{
		Context,
		Poll,
	},
};

use crate::{
	cstr,
	ffi,
	inner,
	interface::Interface,
};

type CallbackStream = crate::stream::ServiceStream<inner::OwnedService, BrowseResult>;

bitflags::bitflags! {
	/// Flags for [`BrowseResult`](struct.BrowseResult.html)
	#[derive(Default)]
	pub struct BrowsedFlags: ffi::DNSServiceFlags {
		/// Indicates at least one more result is pending in the queue.  If
		/// not set there still might be more results coming in the future.
		///
		/// See [`kDNSServiceFlagsMoreComing`](https://developer.apple.com/documentation/dnssd/1823436-anonymous/kdnsserviceflagsmorecoming).
		const MORE_COMING = ffi::FLAGS_MORE_COMING;

		/// Indicates the result is new.  If not set indicates the result
		/// was removed.
		///
		/// See [`kDNSServiceFlagsAdd`](https://developer.apple.com/documentation/dnssd/1823436-anonymous/kdnsserviceflagsadd).
		const ADD = ffi::FLAGS_ADD;
	}
}

/// Pending browse request
///
/// Results are delivered through `Stream`.
#[must_use = "streams do nothing unless polled"]
pub struct Browse {
	stream: crate::fused_err_stream::FusedErrorStream<CallbackStream>,
}

impl Browse {
	pin_utils::unsafe_pinned!(stream: crate::fused_err_stream::FusedErrorStream<CallbackStream>);
}

impl futures_core::Stream for Browse {
	type Item = io::Result<BrowseResult>;

	fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
		self.stream().poll_next(cx)
	}
}

/// Browse result
///
/// See [DNSServiceBrowseReply](https://developer.apple.com/documentation/dnssd/dnsservicebrowsereply).
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub struct BrowseResult {
	/// Flags indicating whether the service was added or removed and
	/// whether there are more pending results.
	pub flags: BrowsedFlags,
	/// Interface the service was found on.
	pub interface: Interface,
	/// Name of the service.
	pub service_name: String,
	/// Type of the service
	pub reg_type: String,
	/// Domain the service was found in
	pub domain: String,
}

impl BrowseResult {
	/// Resolve browse result.
	///
	/// Should check before whether result has the `Add` flag, as
	/// otherwise it probably won't find anything.
	pub fn resolve(&self) -> crate::Resolve {
		crate::resolve(
			self.interface,
			&self.service_name,
			&self.reg_type,
			&self.domain,
		)
	}
}

unsafe extern "C" fn browse_callback(
	_sd_ref: ffi::DNSServiceRef,
	flags: ffi::DNSServiceFlags,
	interface_index: u32,
	error_code: ffi::DNSServiceErrorType,
	service_name: *const c_char,
	reg_type: *const c_char,
	reply_domain: *const c_char,
	context: *mut c_void,
) {
	CallbackStream::run_callback(context, error_code, || {
		let service_name = cstr::from_cstr(service_name)?;
		let reg_type = cstr::from_cstr(reg_type)?;
		let reply_domain = cstr::from_cstr(reply_domain)?;

		Ok(BrowseResult {
			flags: BrowsedFlags::from_bits_truncate(flags),
			interface: Interface::from_raw(interface_index),
			service_name: service_name.to_string(),
			reg_type: reg_type.to_string(),
			domain: reply_domain.to_string(),
		})
	});
}

/// Optional data when browsing for a service; either use its default
/// value or customize it like:
///
/// ```
/// # use async_dnssd::BrowseData;
/// BrowseData {
///     domain: Some("example.com"),
///     ..Default::default()
/// };
/// ```
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub struct BrowseData<'a> {
	/// interface to query records on
	pub interface: Interface,
	/// domain on which to search for the service
	pub domain: Option<&'a str>,
	#[doc(hidden)]
	pub _non_exhaustive: crate::non_exhaustive_struct::NonExhaustiveMarker,
}

impl<'a> Default for BrowseData<'a> {
	fn default() -> Self {
		Self {
			interface: Interface::default(),
			domain: None,
			_non_exhaustive: crate::non_exhaustive_struct::NonExhaustiveMarker,
		}
	}
}

fn _browse_extended(reg_type: &str, data: BrowseData<'_>) -> io::Result<Browse> {
	crate::init();

	let reg_type = cstr::CStr::from(&reg_type)?;
	let domain = cstr::NullableCStr::from(&data.domain)?;

	let stream = CallbackStream::new(move |sender| {
		inner::OwnedService::browse(
			0, // no flags
			data.interface.into_raw(),
			&reg_type,
			&domain,
			Some(browse_callback),
			sender,
		)
	})
	.into();

	Ok(Browse { stream })
}

/// Browse for available services
///
/// `reg_type` specifies the service type to search, e.g. `"_ssh._tcp"`.
///
/// See [`DNSServiceBrowse`](https://developer.apple.com/documentation/dnssd/1804742-dnsservicebrowse).
#[doc(alias = "DNSServiceBrowse")]
pub fn browse_extended(reg_type: &str, data: BrowseData<'_>) -> Browse {
	match _browse_extended(reg_type, data) {
		Ok(r) => r,
		Err(e) => Browse {
			stream: Err(e).into(),
		},
	}
}

/// Browse for available services
///
/// `reg_type` specifies the service type to search, e.g. `"_ssh._tcp"`.
///
/// Uses [`browse_extended`] with default [`BrowseData`].
///
/// See [`DNSServiceBrowse`](https://developer.apple.com/documentation/dnssd/1804742-dnsservicebrowse).
///
/// [`browse_extended`]: fn.browse_extended.html
/// [`BrowseData`]: struct.BrowseData.html
#[doc(alias = "DNSServiceBrowse")]
pub fn browse(reg_type: &str) -> Browse {
	browse_extended(reg_type, BrowseData::default())
}