use std::io::{self, Read, Seek, SeekFrom};

use byteorder::{LittleEndian, ReadBytesExt};

use crate::{Chunk, Header};

pub struct Frame {
	pub byte_count: u32,
	pub frame_duration_milliseconds: u16,
	pub number_of_chunks: u32,
	pub chunks: Vec<Chunk>,
}

impl Frame {
	pub fn from_read<R>(read: &mut R, header: &Header) -> io::Result<Self>
	where
		R: Read + Seek,
	{
		let byte_count = read.read_u32::<LittleEndian>()?;
		read.seek(SeekFrom::Current(2))?;
		let number_of_chunks_old = read.read_u16::<LittleEndian>()?;
		let frame_duration_milliseconds = read.read_u16::<LittleEndian>()?;
		read.seek(SeekFrom::Current(2))?;
		let number_of_chunks_new = read.read_u32::<LittleEndian>()?;

		let number_of_chunks = if number_of_chunks_new == 0 {
			number_of_chunks_old as u32
		} else {
			number_of_chunks_new
		};

		let mut chunks = Vec::with_capacity(number_of_chunks as usize);
		for _ in 0..number_of_chunks {
			chunks.push(Chunk::from_read(read, header)?);
		}

		Ok(Self {
			byte_count,
			frame_duration_milliseconds,
			number_of_chunks,
			chunks,
		})
	}
}