use std::ffi::CString;
use std::marker;
use std::str;

use crate::util::Binding;
use crate::{raw, Buf, Direction, Error};

/// A structure to represent a git [refspec][1].
///
/// Refspecs are currently mainly accessed/created through a `Remote`.
///
/// [1]: http://git-scm.com/book/en/Git-Internals-The-Refspec
pub struct Refspec<'remote> {
    raw: *const raw::git_refspec,
    _marker: marker::PhantomData<&'remote raw::git_remote>,
}

impl<'remote> Refspec<'remote> {
    /// Get the refspec's direction.
    pub fn direction(&self) -> Direction {
        match unsafe { raw::git_refspec_direction(self.raw) } {
            raw::GIT_DIRECTION_FETCH => Direction::Fetch,
            raw::GIT_DIRECTION_PUSH => Direction::Push,
            n => panic!("unknown refspec direction: {}", n),
        }
    }

    /// Get the destination specifier.
    ///
    /// If the destination is not utf-8, None is returned.
    pub fn dst(&self) -> Option<&str> {
        str::from_utf8(self.dst_bytes()).ok()
    }

    /// Get the destination specifier, in bytes.
    pub fn dst_bytes(&self) -> &[u8] {
        unsafe { crate::opt_bytes(self, raw::git_refspec_dst(self.raw)).unwrap() }
    }

    /// Check if a refspec's destination descriptor matches a reference
    pub fn dst_matches(&self, refname: &str) -> bool {
        let refname = CString::new(refname).unwrap();
        unsafe { raw::git_refspec_dst_matches(self.raw, refname.as_ptr()) == 1 }
    }

    /// Get the source specifier.
    ///
    /// If the source is not utf-8, None is returned.
    pub fn src(&self) -> Option<&str> {
        str::from_utf8(self.src_bytes()).ok()
    }

    /// Get the source specifier, in bytes.
    pub fn src_bytes(&self) -> &[u8] {
        unsafe { crate::opt_bytes(self, raw::git_refspec_src(self.raw)).unwrap() }
    }

    /// Check if a refspec's source descriptor matches a reference
    pub fn src_matches(&self, refname: &str) -> bool {
        let refname = CString::new(refname).unwrap();
        unsafe { raw::git_refspec_src_matches(self.raw, refname.as_ptr()) == 1 }
    }

    /// Get the force update setting.
    pub fn is_force(&self) -> bool {
        unsafe { raw::git_refspec_force(self.raw) == 1 }
    }

    /// Get the refspec's string.
    ///
    /// Returns None if the string is not valid utf8.
    pub fn str(&self) -> Option<&str> {
        str::from_utf8(self.bytes()).ok()
    }

    /// Get the refspec's string as a byte array
    pub fn bytes(&self) -> &[u8] {
        unsafe { crate::opt_bytes(self, raw::git_refspec_string(self.raw)).unwrap() }
    }

    /// Transform a reference to its target following the refspec's rules
    pub fn transform(&self, name: &str) -> Result<Buf, Error> {
        let name = CString::new(name).unwrap();
        unsafe {
            let buf = Buf::new();
            try_call!(raw::git_refspec_transform(
                buf.raw(),
                self.raw,
                name.as_ptr()
            ));
            Ok(buf)
        }
    }

    /// Transform a target reference to its source reference following the refspec's rules
    pub fn rtransform(&self, name: &str) -> Result<Buf, Error> {
        let name = CString::new(name).unwrap();
        unsafe {
            let buf = Buf::new();
            try_call!(raw::git_refspec_rtransform(
                buf.raw(),
                self.raw,
                name.as_ptr()
            ));
            Ok(buf)
        }
    }
}

impl<'remote> Binding for Refspec<'remote> {
    type Raw = *const raw::git_refspec;

    unsafe fn from_raw(raw: *const raw::git_refspec) -> Refspec<'remote> {
        Refspec {
            raw,
            _marker: marker::PhantomData,
        }
    }
    fn raw(&self) -> *const raw::git_refspec {
        self.raw
    }
}