use libc;

use std::collections::HashMap;
use std::ffi::{CStr, CString};
use std::mem;
use std::ptr;
use std::str;

use std::path;

use param;
use JailError;

macro_rules! iovec {
    ($key:expr => ($value:expr, $size:expr)) => {
        vec![iovec!($key), iovec!($value, $size)]
    };
    ($key:expr => ()) => {
        vec![iovec!($key), iovec!()]
    };
    ($key:expr => $value:expr) => {
        vec![iovec!($key), iovec!($value)]
    };
    ($key:expr => mut $value:expr) => {
        vec![iovec!($key), iovec!(mut $value)]
    };
    ($value:expr, $size:expr) => {
        libc::iovec {
            iov_base: $value as *mut libc::c_void,
            iov_len: $size,
        }
    };
    ($name:expr) => {
        iovec!($name.as_ptr(), $name.len())
    };
    (mut $name:expr) => {
        iovec!($name.as_mut_ptr(), $name.len())
    };
    () => {
        iovec!(ptr::null::<libc::c_void>(), 0)
    };
}

bitflags! {
    pub struct JailFlags : i32 {
        /// Create the Jail if it doesn't exist
        const CREATE = 0x01;

        /// Update parameters of existing Jail
        const UPDATE = 0x02;

        /// Attach to Jail upon creation
        const ATTACH = 0x04;

        /// Allow getting a dying jail
        const DYING = 0x08;
    }
}

/// Create a jail with a specific path
#[cfg(target_os = "freebsd")]
pub fn jail_create(
    path: &path::Path,
    params: HashMap<String, param::Value>,
) -> Result<i32, JailError> {
    trace!("jail_create(path={:?}, params={:?})", path, params);

    // Note: we keep an owned copy of the raw parameter representations
    // around that we only drop after the unsafe jail_set call.
    // Dropping it earlier would cause a dangling pointer.
    let raw_params: Vec<(Vec<u8>, Vec<u8>)> = params
        .iter()
        .map(|(key, value)| {
            Ok((
                CString::new(key.clone())
                    .map_err(JailError::CStringError)?
                    .into_bytes_with_nul(),
                value.clone().as_bytes()?,
            ))
        })
        .collect::<Result<_, JailError>>()?;

    let mut jiov: Vec<libc::iovec> = raw_params
        .iter()
        .flat_map(|(ref key, ref value)| iovec!(key => value))
        .collect();

    let pathstr = path
        .to_str()
        .ok_or(JailError::SerializeFailed)
        .map(CString::new)?
        .map_err(JailError::CStringError)?
        .into_bytes_with_nul();

    // Set persist and errmsg
    let mut errmsg: [u8; 256] = unsafe { mem::zeroed() };
    jiov.append(
        &mut vec![
            iovec!(b"path\0" => pathstr),
            iovec!(b"errmsg\0" => mut errmsg),
            iovec!(b"persist\0" => ()),
        ]
        .into_iter()
        .flatten()
        .collect(),
    );

    let jid = unsafe {
        libc::jail_set(
            jiov[..].as_mut_ptr() as *mut libc::iovec,
            jiov.len() as u32,
            JailFlags::CREATE.bits,
        )
    };

    let err = unsafe { CStr::from_ptr(errmsg.as_ptr() as *mut i8) }
        .to_string_lossy()
        .to_string();

    match jid {
        e if e < 0 => match errmsg[0] {
            0 => Err(JailError::from_errno()),
            _ => Err(JailError::JailSetError(err)),
        },
        _ => Ok(jid),
    }
}

/// Test if a jail exists. Returns
pub fn jail_exists(jid: i32) -> bool {
    trace!("jail_exists({})", jid);
    let mut errmsg: [u8; 256] = unsafe { mem::zeroed() };
    let mut jiov: Vec<libc::iovec> = vec![
        iovec!(b"jid\0" => (&jid as *const _, mem::size_of::<i32>())),
        iovec!(b"errmsg\0" => mut errmsg),
    ]
    .into_iter()
    .flatten()
    .collect();

    let retjid = unsafe {
        libc::jail_get(
            jiov[..].as_mut_ptr() as *mut libc::iovec,
            jiov.len() as u32,
            JailFlags::empty().bits,
        )
    };

    jid == retjid
}

/// Clear the persist flag
#[cfg(target_os = "freebsd")]
pub fn jail_clearpersist(jid: i32) -> Result<(), JailError> {
    trace!("jail_clearpersist({})", jid);
    let mut errmsg: [u8; 256] = unsafe { mem::zeroed() };
    let mut jiov: Vec<libc::iovec> = vec![
        iovec!(b"jid\0" => (&jid as *const _, mem::size_of::<i32>())),
        iovec!(b"errmsg\0" => mut errmsg),
        iovec!(b"nopersist\0" => ()),
    ]
    .into_iter()
    .flatten()
    .collect();

    let jid = unsafe {
        libc::jail_set(
            jiov[..].as_mut_ptr() as *mut libc::iovec,
            jiov.len() as u32,
            JailFlags::UPDATE.bits,
        )
    };

    let err = unsafe { CStr::from_ptr(errmsg.as_ptr() as *mut i8) }
        .to_string_lossy()
        .to_string();

    match jid {
        e if e < 0 => match errmsg[0] {
            0 => Err(JailError::from_errno()),
            _ => Err(JailError::JailSetError(err)),
        },
        _ => Ok(()),
    }
}

/// Get the `jid` of a jail given the name.
///
/// This function attempts to parse the name into an `i32` first, which is
/// returned if successful.
#[cfg(target_os = "freebsd")]
pub fn jail_getid(name: &str) -> Result<i32, JailError> {
    trace!("jail_getid(name={:?})", name);
    let mut errmsg: [u8; 256] = unsafe { mem::zeroed() };

    if let Ok(jid) = name.parse::<i32>() {
        return Ok(jid);
    };

    let name = CString::new(name).unwrap().into_bytes_with_nul();

    let mut jiov: Vec<libc::iovec> =
        vec![iovec!(b"name\0" => name), iovec!(b"errmsg\0" => mut errmsg)]
            .into_iter()
            .flatten()
            .collect();

    let jid = unsafe {
        libc::jail_get(
            jiov[..].as_mut_ptr() as *mut libc::iovec,
            jiov.len() as u32,
            JailFlags::empty().bits,
        )
    };

    let err = unsafe { CStr::from_ptr(errmsg.as_ptr() as *mut i8) }
        .to_string_lossy()
        .to_string();

    match jid {
        e if e < 0 => match errmsg[0] {
            0 => Err(JailError::from_errno()),
            _ => Err(JailError::JailGetError(err)),
        },
        _ => Ok(jid),
    }
}

/// Get the next `jid` given the last `jid`.
#[cfg(target_os = "freebsd")]
pub fn jail_nextjid(lastjid: i32) -> Result<i32, JailError> {
    trace!("jail_nextjid(lastjid={})", lastjid);
    let mut errmsg: [u8; 256] = unsafe { mem::zeroed() };

    let mut jiov: Vec<libc::iovec> = vec![
        iovec!(b"lastjid\0" => (&lastjid as *const _, mem::size_of::<i32>())),
        iovec!(b"errmsg\0" => mut errmsg),
    ]
    .into_iter()
    .flatten()
    .collect();

    let jid = unsafe {
        libc::jail_get(
            jiov[..].as_mut_ptr() as *mut libc::iovec,
            jiov.len() as u32,
            JailFlags::empty().bits,
        )
    };

    let err = unsafe { CStr::from_ptr(errmsg.as_ptr() as *mut i8) }
        .to_string_lossy()
        .to_string();

    match jid {
        e if e < 0 => match errmsg[0] {
            0 => Err(JailError::from_errno()),
            _ => Err(JailError::JailGetError(err)),
        },
        _ => Ok(jid),
    }
}

/// Remove a jail with the given `jid`.
///
/// This will kill all processes belonging to the jail, and remove any children
/// of that jail.
#[cfg(target_os = "freebsd")]
pub fn jail_remove(jid: i32) -> Result<(), JailError> {
    trace!("jail_remove(jid={})", jid);
    let ret = unsafe { libc::jail_remove(jid) };
    match ret {
        0 => Ok(()),
        -1 => Err(JailError::from_errno()),
        _ => Err(JailError::JailRemoveFailed),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::path::Path;

    #[test]
    fn create_remove() {
        let mut params: HashMap<String, param::Value> = HashMap::new();
        params.insert(
            "name".into(),
            param::Value::String("testjail_create_remove".into()),
        );
        let jid = jail_create(Path::new("/rescue"), params).expect("could not start jail");
        jail_remove(jid).expect("could not remove jail");
    }

    #[test]
    fn id() {
        let mut params: HashMap<String, param::Value> = HashMap::new();
        params.insert("name".into(), param::Value::String("testjail_getid".into()));
        let target_jid = jail_create(Path::new("/rescue"), params).expect("could not start jail");
        let jid = jail_getid("testjail_getid").expect("could not get ID of test jail");
        assert_eq!(jid, target_jid);
        jail_remove(jid).expect("could not remove jail");
    }
}