// Symphonia

// Copyright (c) 2019-2026 The Project Symphonia Developers.

//

// This Source Code Form is subject to the terms of the Mozilla Public

// License, v. 2.0. If a copy of the MPL was not distributed with this

// file, You can obtain one at https://mozilla.org/MPL/2.0/.

use symphonia_core::codecs::audio::well_known::CODEC_ID_ALAC;

use symphonia_common::apple::audio::alac::MagicCookie;

use crate::atoms::stsd::AudioSampleEntry;

use crate::atoms::{

    Atom, AtomHeader, AtomIterator, ReadAtom, Result, decode_error, unsupported_error,

};

#[allow(dead_code)]

#[derive(Debug)]

pub struct AlacAtom {

    /// ALAC extra data (magic cookie).

    extra_data: Box<[u8]>,

}

impl Atom for AlacAtom {

    fn read<B: ReadAtom>(it: &mut AtomIterator<B>, _header: &AtomHeader) -> Result<Self> {

        let (version, flags) = it.read_extended_header()?;

        if version != 0 {

            return unsupported_error("isomp4 (alac): unsupported alac version");

        }

        if flags != 0 {

            return decode_error("isomp4 (alac): flags not zero");

        }

        // The ALAC magic cookie (aka extra data) is either 24 or 48 bytes long.

        let magic_len = match it.data_left()? {

            Some(len @ 24) | Some(len @ 48) => len as usize,

            Some(_) => {

                return decode_error("isomp4 (alac): invalid magic cookie length");

            }

            None => return decode_error("isomp4 (alac): unknown magic cookie length"),

        };

        // Read the magic cookie.

        let extra_data = it.read_boxed_slice_exact(magic_len)?;

        Ok(AlacAtom { extra_data })

    }

}

impl AlacAtom {

    pub fn fill_audio_sample_entry(self, entry: &mut AudioSampleEntry) {

        entry.codec_id = CODEC_ID_ALAC;

        // Try to parse the magic cookie.

        if let Ok(cookie) = MagicCookie::read(&self.extra_data) {

            entry.channels = Some(cookie.channels);

            entry.sample_rate = f64::from(cookie.sample_rate);

        }

        entry.extra_data = Some(self.extra_data);

    }

}