//! Safe wrapper for the `VIDIOC_(G|S|TRY)_FMT` ioctls.
use nix::errno::Errno;
use std::convert::{From, Into, TryFrom, TryInto};
use std::default::Default;
use std::os::unix::io::AsRawFd;
use thiserror::Error;

use crate::bindings;
use crate::bindings::v4l2_format;
use crate::Format;
use crate::FormatConversionError;
use crate::PlaneLayout;
use crate::QueueType;

impl TryFrom<(QueueType, &Format)> for v4l2_format {
    type Error = FormatConversionError;

    fn try_from((queue, format): (QueueType, &Format)) -> Result<Self, Self::Error> {
        Ok(v4l2_format {
            type_: queue as u32,
            fmt: match queue {
                QueueType::VideoCaptureMplane | QueueType::VideoOutputMplane => {
                    bindings::v4l2_format__bindgen_ty_1 {
                        pix_mp: {
                            if format.plane_fmt.len() > bindings::VIDEO_MAX_PLANES as usize {
                                return Err(Self::Error::TooManyPlanes(format.plane_fmt.len()));
                            }

                            let mut pix_mp = bindings::v4l2_pix_format_mplane {
                                width: format.width,
                                height: format.height,
                                pixelformat: format.pixelformat.into(),
                                num_planes: format.plane_fmt.len() as u8,
                                plane_fmt: Default::default(),
                                ..Default::default()
                            };

                            for (plane, v4l2_plane) in
                                format.plane_fmt.iter().zip(pix_mp.plane_fmt.iter_mut())
                            {
                                *v4l2_plane = plane.into();
                            }

                            pix_mp
                        },
                    }
                }
                _ => bindings::v4l2_format__bindgen_ty_1 {
                    pix: {
                        if format.plane_fmt.len() > 1 {
                            return Err(Self::Error::TooManyPlanes(format.plane_fmt.len()));
                        }

                        let (bytesperline, sizeimage) = if !format.plane_fmt.is_empty() {
                            (
                                format.plane_fmt[0].bytesperline,
                                format.plane_fmt[0].sizeimage,
                            )
                        } else {
                            Default::default()
                        };

                        bindings::v4l2_pix_format {
                            width: format.width,
                            height: format.height,
                            pixelformat: format.pixelformat.into(),
                            bytesperline,
                            sizeimage,
                            ..Default::default()
                        }
                    },
                },
            },
        })
    }
}

impl From<&PlaneLayout> for bindings::v4l2_plane_pix_format {
    fn from(plane: &PlaneLayout) -> Self {
        bindings::v4l2_plane_pix_format {
            sizeimage: plane.sizeimage,
            bytesperline: plane.bytesperline,
            ..Default::default()
        }
    }
}

#[doc(hidden)]
mod ioctl {
    use crate::bindings::v4l2_format;
    nix::ioctl_readwrite!(vidioc_g_fmt, b'V', 4, v4l2_format);
    nix::ioctl_readwrite!(vidioc_s_fmt, b'V', 5, v4l2_format);
    nix::ioctl_readwrite!(vidioc_try_fmt, b'V', 64, v4l2_format);
}

#[derive(Debug, Error)]
pub enum GFmtError {
    #[error("error while converting from V4L2 format")]
    FromV4L2FormatConversionError,
    #[error("invalid buffer type requested")]
    InvalidBufferType,
    #[error("unexpected ioctl error: {0}")]
    IoctlError(nix::Error),
}

impl From<GFmtError> for Errno {
    fn from(err: GFmtError) -> Self {
        match err {
            GFmtError::FromV4L2FormatConversionError => Errno::EINVAL,
            GFmtError::InvalidBufferType => Errno::EINVAL,
            GFmtError::IoctlError(e) => e,
        }
    }
}

/// Safe wrapper around the `VIDIOC_G_FMT` ioctl.
pub fn g_fmt<O: TryFrom<v4l2_format>>(fd: &impl AsRawFd, queue: QueueType) -> Result<O, GFmtError> {
    let mut fmt = v4l2_format {
        type_: queue as u32,
        ..Default::default()
    };

    match unsafe { ioctl::vidioc_g_fmt(fd.as_raw_fd(), &mut fmt) } {
        Ok(_) => Ok(fmt
            .try_into()
            .map_err(|_| GFmtError::FromV4L2FormatConversionError)?),
        Err(Errno::EINVAL) => Err(GFmtError::InvalidBufferType),
        Err(e) => Err(GFmtError::IoctlError(e)),
    }
}

#[derive(Debug, Error)]
pub enum SFmtError {
    #[error("error while converting from V4L2 format")]
    FromV4L2FormatConversionError,
    #[error("error while converting to V4L2 format")]
    ToV4L2FormatConversionError,
    #[error("invalid buffer type requested")]
    InvalidBufferType,
    #[error("device currently busy")]
    DeviceBusy,
    #[error("ioctl error: {0}")]
    IoctlError(nix::Error),
}

impl From<SFmtError> for Errno {
    fn from(err: SFmtError) -> Self {
        match err {
            SFmtError::FromV4L2FormatConversionError => Errno::EINVAL,
            SFmtError::ToV4L2FormatConversionError => Errno::EINVAL,
            SFmtError::InvalidBufferType => Errno::EINVAL,
            SFmtError::DeviceBusy => Errno::EBUSY,
            SFmtError::IoctlError(e) => e,
        }
    }
}

/// Safe wrapper around the `VIDIOC_S_FMT` ioctl.
pub fn s_fmt<I: TryInto<v4l2_format>, O: TryFrom<v4l2_format>>(
    fd: &mut impl AsRawFd,
    format: I,
) -> Result<O, SFmtError> {
    let mut fmt: v4l2_format = format
        .try_into()
        .map_err(|_| SFmtError::ToV4L2FormatConversionError)?;

    match unsafe { ioctl::vidioc_s_fmt(fd.as_raw_fd(), &mut fmt) } {
        Ok(_) => Ok(fmt
            .try_into()
            .map_err(|_| SFmtError::FromV4L2FormatConversionError)?),
        Err(Errno::EINVAL) => Err(SFmtError::InvalidBufferType),
        Err(Errno::EBUSY) => Err(SFmtError::DeviceBusy),
        Err(e) => Err(SFmtError::IoctlError(e)),
    }
}

#[derive(Debug, Error)]
pub enum TryFmtError {
    #[error("error while converting from V4L2 format")]
    FromV4L2FormatConversionError,
    #[error("error while converting to V4L2 format")]
    ToV4L2FormatConversionError,
    #[error("invalid buffer type requested")]
    InvalidBufferType,
    #[error("ioctl error: {0}")]
    IoctlError(nix::Error),
}

impl From<TryFmtError> for Errno {
    fn from(err: TryFmtError) -> Self {
        match err {
            TryFmtError::FromV4L2FormatConversionError => Errno::EINVAL,
            TryFmtError::ToV4L2FormatConversionError => Errno::EINVAL,
            TryFmtError::InvalidBufferType => Errno::EINVAL,
            TryFmtError::IoctlError(e) => e,
        }
    }
}

/// Safe wrapper around the `VIDIOC_TRY_FMT` ioctl.
pub fn try_fmt<I: TryInto<v4l2_format>, O: TryFrom<v4l2_format>>(
    fd: &impl AsRawFd,
    format: I,
) -> Result<O, TryFmtError> {
    let mut fmt: v4l2_format = format
        .try_into()
        .map_err(|_| TryFmtError::ToV4L2FormatConversionError)?;

    match unsafe { ioctl::vidioc_try_fmt(fd.as_raw_fd(), &mut fmt) } {
        Ok(_) => Ok(fmt
            .try_into()
            .map_err(|_| TryFmtError::FromV4L2FormatConversionError)?),
        Err(Errno::EINVAL) => Err(TryFmtError::InvalidBufferType),
        Err(e) => Err(TryFmtError::IoctlError(e)),
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use std::convert::TryInto;

    #[test]
    // Convert from Format to multi-planar v4l2_format and back.
    fn mplane_to_v4l2_format() {
        // This is not a real format but let us use unique values per field.
        let mplane = Format {
            width: 632,
            height: 480,
            pixelformat: b"NM12".into(),
            plane_fmt: vec![
                PlaneLayout {
                    sizeimage: 307200,
                    bytesperline: 640,
                },
                PlaneLayout {
                    sizeimage: 153600,
                    bytesperline: 320,
                },
                PlaneLayout {
                    sizeimage: 76800,
                    bytesperline: 160,
                },
            ],
        };
        let v4l2_format = v4l2_format {
            ..(QueueType::VideoCaptureMplane, &mplane).try_into().unwrap()
        };
        let mplane2: Format = v4l2_format.try_into().unwrap();
        assert_eq!(mplane, mplane2);
    }

    #[test]
    // Convert from Format to single-planar v4l2_format and back.
    fn splane_to_v4l2_format() {
        // This is not a real format but let us use unique values per field.
        let splane = Format {
            width: 632,
            height: 480,
            pixelformat: b"NV12".into(),
            plane_fmt: vec![PlaneLayout {
                sizeimage: 307200,
                bytesperline: 640,
            }],
        };
        // Conversion to/from single-planar format.
        let v4l2_format = v4l2_format {
            ..(QueueType::VideoCapture, &splane).try_into().unwrap()
        };
        let splane2: Format = v4l2_format.try_into().unwrap();
        assert_eq!(splane, splane2);

        // Trying to use a multi-planar format with the single-planar API should
        // fail.
        let mplane = Format {
            width: 632,
            height: 480,
            pixelformat: b"NM12".into(),
            // This is not a real format but let us use unique values per field.
            plane_fmt: vec![
                PlaneLayout {
                    sizeimage: 307200,
                    bytesperline: 640,
                },
                PlaneLayout {
                    sizeimage: 153600,
                    bytesperline: 320,
                },
                PlaneLayout {
                    sizeimage: 76800,
                    bytesperline: 160,
                },
            ],
        };
        assert_eq!(
            TryInto::<v4l2_format>::try_into((QueueType::VideoCapture, &mplane)).err(),
            Some(FormatConversionError::TooManyPlanes(3))
        );
    }
}