use std::{
    borrow::Cow,
    convert::{Infallible, TryFrom},
    path::Path,
};

use git_object::bstr::{BStr, BString, ByteSlice, ByteVec};

use crate::{FullNameRef, PartialNameRef};

/// The error used in the [`PartialNameRef`][super::PartialNameRef]::try_from(…) implementations.
pub type Error = git_validate::reference::name::Error;

impl<'a> FullNameRef<'a> {
    /// Convert this name into the relative path identifying the reference location.
    // TODO: use custom `Path` type instead, as this isn't really a path. See ref iteration with prefix for
    //       similar comment.
    pub fn to_path(self) -> Cow<'a, Path> {
        self.0.to_path().expect("UTF-8 conversion always succeeds").into()
    }

    /// Return ourselves as byte string which is a valid refname
    pub fn as_bstr(&self) -> &'a BStr {
        self.0
    }
}

impl<'a> PartialNameRef<'a> {
    /// Convert this name into the relative path possibly identifying the reference location.
    /// Note that it may be only a partial path though.
    pub fn to_partial_path(&'a self) -> Cow<'a, Path> {
        self.0.to_path().expect("UTF-8 conversion always succeeds").into()
    }

    /// Provide the name as binary string which is known to be a valid partial ref name.
    pub fn as_bstr(&'a self) -> &'a BStr {
        self.0.as_ref()
    }
}

impl PartialNameRef<'static> {
    /// Append the `component` to ourselves and validate the newly created partial path.
    ///
    /// Note that this method is meant to have an owned starting point as this is considered
    /// the typical usecase.
    pub fn join(self, component: impl AsRef<[u8]>) -> Result<Self, crate::name::Error> {
        let mut b = self.0.into_owned();
        b.push_byte(b'/');
        b.extend(component.as_ref());
        git_validate::reference::name_partial(b.as_ref())?;
        Ok(PartialNameRef(b.into()))
    }
}

impl<'a> TryFrom<&'a BStr> for FullNameRef<'a> {
    type Error = Error;

    fn try_from(v: &'a BStr) -> Result<Self, Self::Error> {
        Ok(FullNameRef(git_validate::reference::name(v)?))
    }
}

impl<'a> TryFrom<FullNameRef<'a>> for PartialNameRef<'a> {
    type Error = Infallible;

    fn try_from(v: FullNameRef<'a>) -> Result<Self, Self::Error> {
        Ok(PartialNameRef(v.0.into()))
    }
}

impl<'a> TryFrom<&'a BStr> for PartialNameRef<'a> {
    type Error = Error;

    fn try_from(v: &'a BStr) -> Result<Self, Self::Error> {
        Ok(PartialNameRef(git_validate::reference::name_partial(v)?.into()))
    }
}

impl<'a> TryFrom<&'a str> for FullNameRef<'a> {
    type Error = Error;

    fn try_from(v: &'a str) -> Result<Self, Self::Error> {
        let v = v.as_bytes().as_bstr();
        Ok(FullNameRef(git_validate::reference::name(v)?))
    }
}

impl<'a> TryFrom<&'a str> for PartialNameRef<'a> {
    type Error = Error;

    fn try_from(v: &'a str) -> Result<Self, Self::Error> {
        let v = v.as_bytes().as_bstr();
        Ok(PartialNameRef(git_validate::reference::name_partial(v)?.into()))
    }
}

impl<'a> TryFrom<&'a String> for FullNameRef<'a> {
    type Error = Error;

    fn try_from(v: &'a String) -> Result<Self, Self::Error> {
        let v = v.as_bytes().as_bstr();
        Ok(FullNameRef(git_validate::reference::name(v)?))
    }
}

impl<'a> TryFrom<&'a String> for PartialNameRef<'a> {
    type Error = Error;

    fn try_from(v: &'a String) -> Result<Self, Self::Error> {
        let v = v.as_bytes().as_bstr();
        Ok(PartialNameRef(git_validate::reference::name_partial(v)?.into()))
    }
}

impl TryFrom<String> for PartialNameRef<'static> {
    type Error = Error;

    fn try_from(v: String) -> Result<Self, Self::Error> {
        git_validate::reference::name_partial(v.as_bytes().as_bstr())?;
        Ok(PartialNameRef(BString::from(v).into()))
    }
}

impl TryFrom<BString> for PartialNameRef<'static> {
    type Error = Error;

    fn try_from(v: BString) -> Result<Self, Self::Error> {
        git_validate::reference::name_partial(v.as_ref())?;
        Ok(PartialNameRef(v.into()))
    }
}