//! Macros for internal use

macro_rules! after_then_block {
    (then $b:block; $($rest:tt)*) => {
        if_chain!($($rest)*)
    };

    (if let $p:pat = $e:expr; $($rest:tt)*) => {
        $crate::macros::after_then_block!($($rest)*)
    };

    (if $e:expr; $($rest:tt)*) => {
        $crate::macros::after_then_block!($($rest)*)
    };
}
pub(crate) use after_then_block;

macro_rules! if_chain {
    (if let $p:pat = $e:expr; $($rest:tt)*) => {{
        let mut flag = false;
        if_chain!(flag, if let $p = $e; $($rest)*);
        if !flag {
            $crate::macros::after_then_block!($($rest)*);
        }
    }};

    (if $e:expr; $($rest:tt)*) => {{
        let mut flag = false;
        if_chain!(flag, if $e; $($rest)*);
        if !flag {
            $crate::macros::after_then_block!($($rest)*);
        }
    }};

    ($flag:ident, if let $p:pat = $e:expr; $($rest:tt)*) => {
        if let $p = $e {
            $crate::macros::if_chain!($flag, $($rest)*)
        }
    };

    ($flag:ident, if $e:expr; $($rest:tt)*) => {
        if $e {
            $crate::macros::if_chain!($flag, $($rest)*)
        }
    };

    ($flag:ident, then $b:block; $($rest:tt)*) => {{
        $flag = true;
        $b
    }};

    (else $b:block;) => {
        $b
    };
}

pub(crate) use if_chain;

#[test]
#[cfg_attr(feature = "cargo-clippy", allow(clippy::missing_const_for_fn))]
fn test_if_chain() {
    let mut _bar;

    if_chain! {
        if let Some(x) = None::<i32>;
        if let Some(y) = None::<i32>;
        if x == y;
        if let Some(z) = None::<i32>;
        if x == z + 1;
        then {
            let _ = x + y;
            _bar = "foo";
        };

        if let Some(_) = None::<i32>;
        then {
            _bar = "bar";
        };

        else {
            _bar = "baz";
        };
    };
}