use std::ops::Deref;

use {ChannelLayout, format};
use super::codec::Codec;
use ffi::*;

#[derive(PartialEq, Eq, Copy, Clone)]
pub struct Audio {
	codec: Codec,
}

impl Audio {
	pub unsafe fn new(codec: Codec) -> Audio {
		Audio {
			codec: codec,
		}
	}
}

impl Audio {
	pub fn rates(&self) -> Option<RateIter> {
		unsafe {
			if (*self.as_ptr()).supported_samplerates.is_null() {
				None
			}
			else {
				Some(RateIter::new((*self.codec.as_ptr()).supported_samplerates))
			}
		}
	}

	pub fn formats(&self) -> Option<FormatIter> {
		unsafe {
			if (*self.codec.as_ptr()).sample_fmts.is_null() {
				None
			}
			else {
				Some(FormatIter::new((*self.codec.as_ptr()).sample_fmts))
			}
		}
	}

	pub fn channel_layouts(&self) -> Option<ChannelLayoutIter> {
		unsafe {
			if (*self.codec.as_ptr()).channel_layouts.is_null() {
				None
			}
			else {
				Some(ChannelLayoutIter::new((*self.codec.as_ptr()).channel_layouts))
			}
		}
	}
}

impl Deref for Audio {
	type Target = Codec;

	fn deref(&self) -> &Self::Target {
		&self.codec
	}
}

pub struct RateIter {
	ptr: *const i32,
}

impl RateIter {
	pub fn new(ptr: *const i32) -> Self {
		RateIter { ptr: ptr }
	}
}

impl Iterator for RateIter {
	type Item = i32;

	fn next(&mut self) -> Option<<Self as Iterator>::Item> {
		unsafe {
			if *self.ptr == 0 {
				return None;
			}

			let rate = *self.ptr;
			self.ptr = self.ptr.offset(1);

			Some(rate)
		}
	}
}

pub struct FormatIter {
	ptr: *const AVSampleFormat,
}

impl FormatIter {
	pub fn new(ptr: *const AVSampleFormat) -> Self {
		FormatIter { ptr: ptr }
	}
}

impl Iterator for FormatIter {
	type Item = format::Sample;

	fn next(&mut self) -> Option<<Self as Iterator>::Item> {
		unsafe {
			if *self.ptr == AVSampleFormat::AV_SAMPLE_FMT_NONE {
				return None;
			}

			let format = (*self.ptr).into();
			self.ptr   = self.ptr.offset(1);

			Some(format)
		}
	}
}

pub struct ChannelLayoutIter {
	ptr: *const u64,
}

impl ChannelLayoutIter {
	pub fn new(ptr: *const u64) -> Self {
		ChannelLayoutIter { ptr: ptr }
	}

	pub fn best(self, max: i32) -> ChannelLayout {
		self.fold(::channel_layout::MONO, |acc, cur|
			if cur.channels() > acc.channels() && cur.channels() <= max {
				cur
			}
			else {
				acc
			})
	}
}

impl Iterator for ChannelLayoutIter {
	type Item = ChannelLayout;

	fn next(&mut self) -> Option<<Self as Iterator>::Item> {
		unsafe {
			if *self.ptr == 0 {
				return None;
			}

			let layout = ChannelLayout::from_bits_truncate(*self.ptr);
			self.ptr   = self.ptr.offset(1);

			Some(layout)
		}
	}
}