#![warn(missing_docs)]

//! `mp4san` is an MP4 format "sanitizer".
//!
//! Currently the sanitizer always performs the following functions:
//!
//! - Return all presentation metadata present in the input as a self-contained contiguous byte array.
//! - Find and return a pointer to the span in the input containing the (contiguous) media data.
//!
//! "Presentation" metadata means any metadata which is required by an MP4 player to play the file. "Self-contained and
//! contiguous" means that the returned metadata can be concatenated with the media data to form a valid MP4 file.
//!
//! The original metadata may or may not need to be modified in order to perform these functions. In the case that the
//! original metadata does not need to be modified, the returned [`SanitizedMetadata::metadata`] will be [`None`] to
//! prevent needless data copying.
//!
//! # Unsupported MP4 features
//!
//! The sanitizer does not currently support:
//!
//! - "Fragmented" MP4 files, which are mostly used for adaptive-bitrate streaming.
//! - Discontiguous media data, i.e. media data (`mdat`) boxes interspersed with presentation metadata (`moov`).
//! - Media data references (`dref`) pointing to separate files.
//! - Any similar format, e.g. Quicktime File Format (`mov`) or the legacy MP4 version 1, which does not contain the
//!   [`isom` compatible brand](COMPATIBLE_BRAND) in its file type header (`ftyp`).
//!
//! # Usage
//!
//! The main entry points to the sanitizer are [`sanitize`]/[`sanitize_async`], which take a [`Read`] + [`Skip`] input.
//! The [`Skip`] trait represents a subset of the [`Seek`] trait; an input stream which can be skipped forward, but not
//! necessarily seeked to arbitrary positions.
//!
//! ```
//! # use mp4san_test::{example_ftyp, example_mdat, example_moov};
//! #
//! let example_input = [example_ftyp(), example_mdat(), example_moov()].concat();
//!
//! let sanitized = mp4san::sanitize(std::io::Cursor::new(example_input))?;
//!
//! assert_eq!(sanitized.metadata, Some([example_ftyp(), example_moov()].concat()));
//! assert_eq!(sanitized.data.offset, example_ftyp().len() as u64);
//! assert_eq!(sanitized.data.len, example_mdat().len() as u64);
//! # Ok::<(), mp4san::Error>(())
//! ```
//!
//! The [`parse`] module also contains a less stable and undocumented API which can be used to parse individual MP4 box
//! types.
//!
//! [`Seek`]: std::io::Seek

// Used by the derive macros' generated code.
extern crate self as mp4san;

#[macro_use]
extern crate mediasan_common;

pub mod error;
pub mod parse;
mod util;

use std::io::Read;
use std::pin::Pin;

use derive_builder::Builder;
use derive_more::Display;
use futures_util::io::BufReader;
use futures_util::{pin_mut, AsyncBufReadExt, AsyncRead};
use mediasan_common::sync;
use mediasan_common::util::{checked_add_signed, IoResultExt};
use mediasan_common::AsyncSkipExt;

use crate::error::Report;
use crate::parse::error::{MultipleBoxes, WhileParsingBox};
use crate::parse::{BoxHeader, BoxType, FourCC, FtypBox, MoovBox, Mp4Box, Mp4Value, ParseError, StblCoMut};

//
// public types
//

pub use crate::error::Error;

#[derive(Builder, Clone)]
#[builder(build_fn(name = "try_build"))]
/// Configuration for the MP4 sanitizer.
pub struct Config {
    /// The maximum size of metadata to support.
    ///
    /// This is useful to set an upper bound on memory consumption in the parser.
    ///
    /// The default is 1 GiB.
    #[builder(default = "1024 * 1024 * 1024")]
    pub max_metadata_size: u64,
}

/// Sanitized metadata returned by the sanitizer.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct SanitizedMetadata {
    /// The sanitized metadata from the given input, as a self-contained contiguous byte array.
    ///
    /// "Self-contained and contiguous" means that the metadata can be concatenated with the [media data](Self::data) to
    /// form a valid MP4 file.
    ///
    /// If the original metadata did not need to be modified, this will be [`None`].
    pub metadata: Option<Vec<u8>>,

    /// A pointer to the span in the input containing the (contiguous) media data.
    pub data: InputSpan,
}

pub use mediasan_common::{AsyncSkip, InputSpan, SeekSkipAdapter, Skip};

/// The ISO Base Media File Format "compatble brand" recognized by the sanitizer.
///
/// This compatible brand must be present in the input's file type header (`ftyp`) in order to be parsed by the
/// sanitizer.
pub const COMPATIBLE_BRAND: FourCC = FourCC { value: *b"isom" };

//
// private types
//

#[derive(Clone, Copy, Debug, Display)]
#[display(fmt = "box data too large: {} > {}", _0, _1)]
struct BoxDataTooLarge(u64, u64);

const MAX_FTYP_SIZE: u64 = 1024;

//
// public functions
//

/// Sanitize an MP4 input, with the default [`Config`].
///
/// The `input` must implement [`Read`] + [`Skip`], where [`Skip`] represents a subset of the [`Seek`] trait; an input
/// stream which can be skipped forward, but not necessarily seeked to arbitrary positions.
///
/// See the [module-level documentation](self) for usage examples.
///
/// # Errors
///
/// If the input cannot be parsed, or an IO error occurs, an [`Error`] is returned.
///
/// [`Seek`]: std::io::Seek
pub fn sanitize<R: Read + Skip + Unpin>(input: R) -> Result<SanitizedMetadata, Error> {
    sync::sanitize(input, sanitize_async)
}

/// Sanitize an MP4 input, with the given [`Config`].
///
/// The `input` must implement [`Read`] + [`Skip`], where [`Skip`] represents a subset of the [`Seek`] trait; an input
/// stream which can be skipped forward, but not necessarily seeked to arbitrary positions.
///
/// ```
/// # use mp4san_test::{example_ftyp, example_mdat, example_moov};
/// #
/// let example_input = [example_ftyp(), example_mdat(), example_moov()].concat();
///
/// let config = mp4san::Config::builder().max_metadata_size(example_moov().len() as u64).build();
/// let sanitized = mp4san::sanitize_with_config(std::io::Cursor::new(example_input), config)?;
///
/// assert_eq!(sanitized.metadata, Some([example_ftyp(), example_moov()].concat()));
/// assert_eq!(sanitized.data.offset, example_ftyp().len() as u64);
/// assert_eq!(sanitized.data.len, example_mdat().len() as u64);
/// #
/// # Ok::<(), mp4san::Error>(())
/// ```
///
/// # Errors
///
/// If the input cannot be parsed, or an IO error occurs, an [`Error`] is returned.
///
/// [`Seek`]: std::io::Seek
pub fn sanitize_with_config<R: Read + Skip + Unpin>(input: R, config: Config) -> Result<SanitizedMetadata, Error> {
    sync::sanitize(input, |input| sanitize_async_with_config(input, config))
}

/// Sanitize an MP4 input asynchronously, with the default [`Config`].
///
/// The `input` must implement [`AsyncRead`] + [`AsyncSkip`], where [`AsyncSkip`] represents a subset of the
/// [`AsyncSeek`] trait; an input stream which can be skipped forward, but not necessarily seeked to arbitrary
/// positions.
///
/// # Examples
///
/// ```
/// # use mp4san::sanitize_async;
/// # use mp4san_test::{example_ftyp, example_mdat, example_moov};
/// #
/// # fn main() -> Result<(), mp4san::Error> {
/// #     futures_util::FutureExt::now_or_never(run()).unwrap()
/// # }
/// #
/// # async fn run() -> Result<(), mp4san::Error> {
/// let example_input = [example_ftyp(), example_mdat(), example_moov()].concat();
///
/// let sanitized = sanitize_async(futures_util::io::Cursor::new(example_input)).await?;
///
/// assert_eq!(sanitized.metadata, Some([example_ftyp(), example_moov()].concat()));
/// assert_eq!(sanitized.data.offset, example_ftyp().len() as u64);
/// assert_eq!(sanitized.data.len, example_mdat().len() as u64);
/// # Ok(())
/// # }
/// ```
///
/// # Errors
///
/// If the input cannot be parsed, or an IO error occurs, an [`Error`] is returned.
///
/// [`AsyncSeek`]: futures_util::io::AsyncSeek
pub async fn sanitize_async<R: AsyncRead + AsyncSkip>(input: R) -> Result<SanitizedMetadata, Error> {
    sanitize_async_with_config(input, Config::default()).await
}

/// Sanitize an MP4 input asynchronously, with the given [`Config`].
///
/// The `input` must implement [`AsyncRead`] + [`AsyncSkip`], where [`AsyncSkip`] represents a subset of the
/// [`AsyncSeek`] trait; an input stream which can be skipped forward, but not necessarily seeked to arbitrary
/// positions.
///
/// # Examples
///
/// ```
/// # use mp4san::{sanitize_async_with_config, Config};
/// # use mp4san_test::{example_ftyp, example_mdat, example_moov};
/// #
/// # fn main() -> Result<(), mp4san::Error> {
/// #     futures_util::FutureExt::now_or_never(run()).unwrap()
/// # }
/// #
/// # async fn run() -> Result<(), mp4san::Error> {
/// let example_input = [example_ftyp(), example_mdat(), example_moov()].concat();
///
/// let config = Config::builder().max_metadata_size(example_moov().len() as u64).build();
/// let sanitized = sanitize_async_with_config(futures_util::io::Cursor::new(example_input), config).await?;
///
/// assert_eq!(sanitized.metadata, Some([example_ftyp(), example_moov()].concat()));
/// assert_eq!(sanitized.data.offset, example_ftyp().len() as u64);
/// assert_eq!(sanitized.data.len, example_mdat().len() as u64);
/// # Ok(())
/// # }
/// ```
///
/// # Errors
///
/// If the input cannot be parsed, or an IO error occurs, an [`Error`] is returned.
///
/// [`AsyncSeek`]: futures_util::io::AsyncSeek
pub async fn sanitize_async_with_config<R: AsyncRead + AsyncSkip>(
    input: R,
    config: Config,
) -> Result<SanitizedMetadata, Error> {
    let reader = BufReader::with_capacity(BoxHeader::MAX_SIZE as usize, input);
    pin_mut!(reader);

    let mut ftyp: Option<Mp4Box<FtypBox>> = None;
    let mut moov: Option<Mp4Box<MoovBox>> = None;
    let mut data: Option<InputSpan> = None;
    let mut moov_offset = None;

    while !reader.as_mut().fill_buf().await?.is_empty() {
        let start_pos = reader.as_mut().stream_position().await?;

        let header = BoxHeader::read(&mut reader)
            .await
            .map_eof(|_| Error::Parse(report_attach!(ParseError::TruncatedBox, "while parsing box header")))?;

        match header.box_type() {
            name @ (BoxType::FREE | BoxType::SKIP) => {
                let box_size = skip_box(reader.as_mut(), &header).await? + header.encoded_len();
                log::info!("{name} @ 0x{start_pos:08x}: {box_size} bytes");

                // Try to extend any already accumulated data in case there's more mdat boxes to come.
                if let Some(data) = &mut data {
                    if data.offset + data.len == start_pos {
                        data.len += box_size;
                    }
                }
            }

            BoxType::FTYP => {
                ensure_attach!(
                    ftyp.is_none(),
                    ParseError::InvalidBoxLayout,
                    MultipleBoxes(BoxType::FTYP)
                );
                let mut read_ftyp = Mp4Box::read_data(reader.as_mut(), header, MAX_FTYP_SIZE).await?;
                let ftyp_data: &mut FtypBox = read_ftyp.data.parse()?;
                let compatible_brand_count = ftyp_data.compatible_brands().len();
                let FtypBox { major_brand, minor_version, .. } = ftyp_data;
                log::info!("ftyp @ 0x{start_pos:08x}: {major_brand} version {minor_version}, {compatible_brand_count} compatible brands");

                ensure_attach!(
                    ftyp_data.compatible_brands().any(|b| b == COMPATIBLE_BRAND),
                    ParseError::UnsupportedFormat(ftyp_data.major_brand)
                );

                ftyp = Some(read_ftyp);
            }

            // NB: ISO 14496-12-2012 specifies a default ftyp, but we don't currently use it. The spec says that it
            // contains a single compatible brand, "mp41", and notably not "isom" which is the ISO spec we follow for
            // parsing now. This implies that there's additional stuff in "mp41" which is not in "isom". "mp41" is also
            // very old at this point, so it'll require additional research/work to be able to parse/remux it.
            _ if ftyp.is_none() => {
                bail_attach!(ParseError::InvalidBoxLayout, "ftyp is not the first significant box");
            }

            BoxType::MDAT => {
                let box_size = skip_box(reader.as_mut(), &header).await? + header.encoded_len();
                log::info!("mdat @ 0x{start_pos:08x}: {box_size} bytes");

                if let Some(data) = &mut data {
                    // Try to extend already accumulated data.
                    ensure_attach!(
                        data.offset + data.len == start_pos,
                        ParseError::UnsupportedBoxLayout,
                        "discontiguous mdat boxes",
                    );
                    data.len += box_size;
                } else {
                    data = Some(InputSpan { offset: start_pos, len: box_size });
                }
            }

            BoxType::MOOV => {
                let mut read_moov = Mp4Box::read_data(reader.as_mut(), header, config.max_metadata_size).await?;

                let moov_data: &mut MoovBox = read_moov.data.parse()?;
                let trak_chunk_counts = moov_data
                    .traks()
                    .map(|trak| Ok::<_, Report<_>>(trak?.co_mut()?.entry_count()));
                let chunk_count = trak_chunk_counts.reduce(|a, b| Ok(a? + b?)).unwrap_or(Ok(0))?;
                let trak_count = moov_data.traks().count();

                log::info!("moov @ 0x{start_pos:08x}: {trak_count} traks {chunk_count} chunks");
                moov = Some(read_moov);
                moov_offset = Some(start_pos);
            }

            name @ (BoxType::META | BoxType::MECO) => {
                let box_size = skip_box(reader.as_mut(), &header).await? + header.encoded_len();
                log::info!("{name} @ 0x{start_pos:08x}: {box_size} bytes");

                // Try to extend any already accumulated data in case there's more mdat boxes to come.
                if let Some(data) = &mut data {
                    if data.offset + data.len == start_pos {
                        data.len += box_size;
                    }
                }
            }

            name => {
                let box_size = skip_box(reader.as_mut(), &header).await? + header.encoded_len();
                log::info!("{name} @ 0x{start_pos:08x}: {box_size} bytes");
                bail_attach!(ParseError::UnsupportedBox(name));
            }
        }
    }

    let Some(ftyp) = ftyp else {
        bail_attach!(ParseError::MissingRequiredBox(BoxType::FTYP));
    };
    let (Some(moov), Some(moov_offset)) = (moov, moov_offset) else {
        bail_attach!(ParseError::MissingRequiredBox(BoxType::MOOV));
    };
    let Some(data) = data else {
        bail_attach!(ParseError::MissingRequiredBox(BoxType::MDAT));
    };

    // Return early if there's nothing to sanitize. Since the only thing the sanitizer does currently is move the moov
    // to before the mdat to make the mp4 streamable, return if we don't need to do that.
    if moov_offset < data.offset {
        log::info!("metadata: nothing to sanitize");
        return Ok(SanitizedMetadata { metadata: None, data });
    }

    // Make sure none of the metadata boxes use BoxSize::UntilEof, as we want the caller to be able to concatenate movie
    // data to the end of the metadata.
    let ftyp = Mp4Box::with_data(ftyp.data)?;
    let mut moov = Mp4Box::with_data(moov.data)?;

    // Add a free box to pad, if one will fit, if the mdat box would move backward. If one won't fit, or if the mdat box
    // would move forward, adjust mdat offsets in stco/co64 the amount it was displaced.
    let metadata_len = ftyp.encoded_len() + moov.encoded_len();
    let mut pad_size = 0;
    const PAD_HEADER_SIZE: u64 = BoxHeader::with_u32_data_size(BoxType::FREE, 0).encoded_len();
    const MAX_PAD_SIZE: u64 = u32::MAX as u64 - PAD_HEADER_SIZE;
    match data.offset.checked_sub(metadata_len) {
        Some(0) => {
            log::info!("metadata: 0x{metadata_len:08x} bytes");
        }
        Some(size @ PAD_HEADER_SIZE..=MAX_PAD_SIZE) => {
            pad_size = size;
            log::info!("metadata: 0x{metadata_len:08x} bytes; adding padding of 0x{pad_size:08x} bytes");
        }
        mdat_backward_displacement => {
            let mdat_displacement = match mdat_backward_displacement {
                Some(mdat_backward_displacement) => {
                    mdat_backward_displacement.try_into().ok().and_then(i32::checked_neg)
                }
                None => metadata_len.checked_sub(data.offset).unwrap().try_into().ok(),
            };
            let mdat_displacement: i32 = mdat_displacement
                .ok_or_else(|| report_attach!(ParseError::UnsupportedBoxLayout, "mdat displaced too far"))?;

            log::info!("metadata: 0x{metadata_len:08x} bytes; displacing chunk offsets by 0x{mdat_displacement:08x}");

            for trak in &mut moov.data.parse()?.traks() {
                let co = trak?.co_mut()?;
                if let StblCoMut::Stco(stco) = co {
                    for mut entry in &mut stco.entries_mut() {
                        let value = entry.get().unwrap_or_else(|_| unreachable!());
                        entry.set(
                            checked_add_signed(value, mdat_displacement).ok_or_else(|| {
                                report_attach!(ParseError::InvalidInput, "chunk offset not within mdat")
                            })?,
                        );
                    }
                } else if let StblCoMut::Co64(co64) = co {
                    for mut entry in &mut co64.entries_mut() {
                        let value = entry.get().unwrap_or_else(|_| unreachable!());
                        entry.set(
                            checked_add_signed(value, mdat_displacement.into()).ok_or_else(|| {
                                report_attach!(ParseError::InvalidInput, "chunk offset not within mdat")
                            })?,
                        );
                    }
                }
            }
        }
    }

    let mut metadata = Vec::with_capacity((metadata_len + pad_size) as usize);
    ftyp.put_buf(&mut metadata);
    moov.put_buf(&mut metadata);
    if pad_size != 0 {
        let pad_header = BoxHeader::with_u32_data_size(BoxType::FREE, (pad_size - PAD_HEADER_SIZE) as u32);
        pad_header.put_buf(&mut metadata);
        metadata.resize((metadata_len + pad_size) as usize, 0);
    }

    Ok(SanitizedMetadata { metadata: Some(metadata), data })
}

//
// Config impls
//

impl Config {
    /// Construct a builder for `Config`.
    ///
    /// See the documentation for [`ConfigBuilder`].
    pub fn builder() -> ConfigBuilder {
        ConfigBuilder::default()
    }
}

impl Default for Config {
    fn default() -> Self {
        Self::builder().build()
    }
}

//
// ConfigBuilder impls
//

impl ConfigBuilder {
    /// Build a new [`Config`].
    pub fn build(&self) -> Config {
        self.try_build().unwrap()
    }
}

//
// private functions
//

/// Skip a box's data assuming its header has already been read.
///
/// Returns the amount of data that was skipped.
async fn skip_box<R: AsyncRead + AsyncSkip>(
    mut reader: Pin<&mut BufReader<R>>,
    header: &BoxHeader,
) -> Result<u64, Error> {
    let box_data_size = match header.box_data_size()? {
        Some(box_size) => box_size,
        None => reader.as_mut().stream_len().await? - reader.as_mut().stream_position().await?,
    };
    reader.skip(box_data_size).await.map_eof(|_| {
        Error::Parse(report_attach!(
            ParseError::TruncatedBox,
            WhileParsingBox(header.box_type())
        ))
    })?;
    Ok(box_data_size)
}

#[cfg(doctest)]
#[doc = include_str!("../README.md")]
pub mod readme {}

#[cfg(test)]
mod test {
    use std::io;

    use assert_matches::assert_matches;

    use crate::parse::box_type::{CO64, FREE, FTYP, MDAT, MDIA, MECO, META, MINF, MOOV, SKIP, STBL, STCO, TRAK};
    use crate::util::test::{
        init_logger, sanitized_data, test_ftyp, test_moov, test_mp4, write_test_mdat, ISOM, MP41, MP42, TEST_UUID,
    };

    use super::*;

    #[test]
    fn until_eof_sized_moov() {
        init_logger();

        let mut data = vec![];
        let mut metadata = vec![];
        test_ftyp().build().put_buf(&mut data);
        test_ftyp().build().put_buf(&mut metadata);
        let mdat = write_test_mdat(&mut data, b"abcdefg");

        let moov_pos = data.len();
        test_moov().build().put_buf(&mut data);
        test_moov().build().put_buf(&mut metadata);
        BoxHeader::until_eof(MOOV).put_buf(&mut &mut data[moov_pos..]);

        let sanitized = sanitize(io::Cursor::new(&data)).unwrap();
        assert_eq!(sanitized.data, mdat);
        assert_eq!(sanitized.metadata, Some(metadata));
        sanitize(io::Cursor::new(sanitized_data(sanitized, &data))).unwrap();
    }

    #[test]
    fn until_eof_sized_mdat() {
        let test = test_mp4()
            .boxes(&[FTYP, MOOV, MDAT][..])
            .mdat_data(&b"abcdefg"[..])
            .mdat_data_until_eof()
            .build();
        test.sanitize_ok_noop();
    }

    #[test]
    fn skip() {
        test_mp4().mdat_data(&b"abcdefg"[..]).build().sanitize_ok();
    }

    #[test]
    fn max_input_length() {
        let mut test = test_mp4().boxes(&[FTYP, MOOV, MDAT][..]).mdat_data(vec![]).clone();
        let test_data_len = test.mdat_data_len(u64::MAX - 16).build().data.len() as u64;
        let test = test.mdat_data_len(u64::MAX - test_data_len).build();
        let sanitized = sanitize(test.clone()).unwrap();
        assert_eq!(sanitized.data, test.mdat);
        assert_eq!(sanitized.data.offset + sanitized.data.len, u64::MAX);
        assert_eq!(sanitized.metadata, None);
    }

    #[test]
    fn input_length_overflow() {
        let mut test = test_mp4().mdat_data(vec![]).clone();
        let test_data_len = test.mdat_data_len(u64::MAX - 16).build().data.len() as u64;
        let test = test.mdat_data_len(u64::MAX - test_data_len + 1).build();
        sanitize(test).unwrap_err();
    }

    #[test]
    fn box_size_overflow() {
        let test = test_mp4().mdat_data_len(u64::MAX - 16).build();
        sanitize(test).unwrap_err();
    }

    #[test]
    fn ftyp_too_large() {
        let mut compatible_brands = vec![];
        while compatible_brands.len() * COMPATIBLE_BRAND.value.len() < MAX_FTYP_SIZE as usize {
            compatible_brands.push(COMPATIBLE_BRAND);
        }

        let test = test_mp4()
            .ftyp(test_ftyp().compatible_brands(compatible_brands).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::InvalidInput);
        });
    }

    #[test]
    fn max_moov_size() {
        let test_spec = test_mp4().build_spec().unwrap();
        let config = Config::builder()
            .max_metadata_size(test_spec.moov().build().encoded_len())
            .build();
        test_spec.build().sanitize_ok_with_config(config);
    }

    #[test]
    fn moov_too_large() {
        let test_spec = test_mp4().build_spec().unwrap();
        let config = Config::builder()
            .max_metadata_size(test_spec.moov().build().data.encoded_len() - 1)
            .build();
        let test = test_spec.build();
        test.sanitize_ok();
        assert_matches!(sanitize_with_config(test, config).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::InvalidInput);
        });
    }

    #[test]
    fn mdat_after_moov() {
        test_mp4().boxes(&[FTYP, MOOV, MDAT][..]).build().sanitize_ok_noop();
    }

    #[test]
    fn no_ftyp() {
        let test = test_mp4().boxes(&[MOOV, MDAT][..]).build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::InvalidBoxLayout);
        });
    }

    #[test]
    fn multiple_ftyp() {
        let test = test_mp4().boxes(&[FTYP, FTYP, MOOV, MDAT][..]).build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::InvalidBoxLayout);
        });
    }

    #[test]
    fn ftyp_not_first_box() {
        let test = test_mp4().boxes(&[FREE, FREE, FTYP, MDAT, MOOV][..]).build();
        test.sanitize_ok();
    }

    #[test]
    fn ftyp_not_first_significant_box() {
        let test = test_mp4().boxes(&[MOOV, FTYP, MDAT][..]).build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::InvalidBoxLayout);
        });
    }

    #[test]
    fn no_moov() {
        let test = test_mp4().boxes(&[FTYP, MDAT][..]).build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::MissingRequiredBox(MOOV));
        });
    }

    #[test]
    fn no_mdat() {
        let test = test_mp4().boxes(&[FTYP, MOOV][..]).build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::MissingRequiredBox(MDAT));
        });
    }

    #[test]
    fn free_boxes_in_metadata() {
        let test = test_mp4().boxes(&[FTYP, FREE, SKIP, MDAT, MOOV, FREE][..]).build();
        test.sanitize_ok();
    }

    #[test]
    fn free_boxes_after_mdat() {
        let test = test_mp4().boxes(&[FTYP, MDAT, SKIP, FREE, MOOV][..]).build();
        test.sanitize_ok();
    }

    #[test]
    fn meta_boxes_in_metadata() {
        let test = test_mp4().boxes(&[FTYP, MDAT, MOOV, META, MECO][..]).build();
        test.sanitize_ok();
    }

    #[test]
    fn meta_boxes_after_mdat() {
        let test = test_mp4().boxes(&[FTYP, MDAT, META, MDAT, MECO, MOOV][..]).build();
        test.sanitize_ok();
    }

    #[test]
    fn multiple_mdat() {
        test_mp4()
            .boxes(&[FTYP, MDAT, FREE, MDAT, MDAT, FREE, MOOV][..])
            .build()
            .sanitize_ok();
    }

    #[test]
    fn uuid() {
        let test = test_mp4().boxes(&[FTYP, MOOV, TEST_UUID, MDAT][..]).build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::UnsupportedBox(TEST_UUID));
        });
    }

    #[test]
    fn mp41() {
        let test = test_mp4()
            .ftyp(test_ftyp().major_brand(MP41).add_compatible_brand(MP41).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::UnsupportedFormat(MP41));
        });
    }

    #[test]
    fn mp42() {
        let ftyp = test_ftyp()
            .major_brand(MP42)
            .compatible_brands(vec![MP42, ISOM])
            .clone();
        let test = test_mp4().ftyp(ftyp).build();
        test.sanitize_ok();
    }

    #[test]
    fn no_compatible_brands() {
        let test = test_mp4()
            .ftyp(test_ftyp().major_brand(ISOM).compatible_brands(vec![]).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::UnsupportedFormat(ISOM));
        });
    }

    #[test]
    fn no_trak() {
        let test = test_mp4().moov(test_moov().trak(false).clone()).build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::MissingRequiredBox(TRAK));
        });
    }

    #[test]
    fn no_mdia() {
        let test = test_mp4()
            .boxes(&[FTYP, MDAT, MOOV][..])
            .moov(test_moov().mdia(false).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::MissingRequiredBox(MDIA));
        });
    }

    #[test]
    fn no_minf() {
        let test = test_mp4()
            .boxes(&[FTYP, MDAT, MOOV][..])
            .moov(test_moov().minf(false).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::MissingRequiredBox(MINF));
        });
    }

    #[test]
    fn no_stbl() {
        let test = test_mp4()
            .boxes(&[FTYP, MDAT, MOOV][..])
            .moov(test_moov().stbl(false).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::MissingRequiredBox(STBL));
        });
    }

    #[test]
    fn no_stco() {
        let test = test_mp4()
            .boxes(&[FTYP, MDAT, MOOV][..])
            .moov(test_moov().stco(false).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::MissingRequiredBox(STCO | CO64));
        });
    }

    #[test]
    fn co64() {
        test_mp4()
            .boxes(&[FTYP, MDAT, MOOV][..])
            .moov(test_moov().stco(false).co64(true).clone())
            .build()
            .sanitize_ok();
    }

    #[test]
    fn stco_and_co64() {
        let test = test_mp4()
            .boxes(&[FTYP, MDAT, MOOV][..])
            .moov(test_moov().co64(true).clone())
            .build();
        assert_matches!(sanitize(test).unwrap_err(), Error::Parse(err) => {
            assert_matches!(err.into_inner(), ParseError::InvalidBoxLayout);
        });
    }
}