use ide_db::syntax_helpers::insert_whitespace_into_node::insert_ws_into;
use syntax::ast::{self, AstNode};

use crate::{AssistContext, AssistId, AssistKind, Assists};

// Assist: inline_macro
//
// Takes a macro and inlines it one step.
//
// ```
// macro_rules! num {
//     (+$($t:tt)+) => (1 + num!($($t )+));
//     (-$($t:tt)+) => (-1 + num!($($t )+));
//     (+) => (1);
//     (-) => (-1);
// }
//
// fn main() {
//     let number = num$0!(+ + + - + +);
//     println!("{number}");
// }
// ```
// ->
// ```
// macro_rules! num {
//     (+$($t:tt)+) => (1 + num!($($t )+));
//     (-$($t:tt)+) => (-1 + num!($($t )+));
//     (+) => (1);
//     (-) => (-1);
// }
//
// fn main() {
//     let number = 1+num!(+ + - + +);
//     println!("{number}");
// }
// ```
pub(crate) fn inline_macro(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
    let unexpanded = ctx.find_node_at_offset::<ast::MacroCall>()?;
    let expanded = insert_ws_into(ctx.sema.expand(&unexpanded)?.clone_for_update());

    let text_range = unexpanded.syntax().text_range();

    acc.add(
        AssistId("inline_macro", AssistKind::RefactorRewrite),
        format!("Inline macro"),
        text_range,
        |builder| builder.replace(text_range, expanded.to_string()),
    )
}

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

    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};

    macro_rules! simple_macro {
        () => {
            r#"
macro_rules! foo {
    (foo) => (true);
    () => (false);
}
"#
        };
    }
    macro_rules! double_macro {
        () => {
            r#"
macro_rules! bar {
    (bar) => (true);
    ($($tt:tt)?) => (false);
}
macro_rules! foo {
    (foo) => (true);
    (bar) => (bar!(bar));
    ($($tt:tt)?) => (bar!($($tt)?));
}
"#
        };
    }

    macro_rules! complex_macro {
        () => {
            r#"
macro_rules! num {
    (+$($t:tt)+) => (1 + num!($($t )+));
    (-$($t:tt)+) => (-1 + num!($($t )+));
    (+) => (1);
    (-) => (-1);
}
"#
        };
    }
    #[test]
    fn inline_macro_target() {
        check_assist_target(
            inline_macro,
            concat!(simple_macro!(), r#"fn f() { let a = foo$0!(foo); }"#),
            "foo!(foo)",
        );
    }

    #[test]
    fn inline_macro_target_start() {
        check_assist_target(
            inline_macro,
            concat!(simple_macro!(), r#"fn f() { let a = $0foo!(foo); }"#),
            "foo!(foo)",
        );
    }

    #[test]
    fn inline_macro_target_end() {
        check_assist_target(
            inline_macro,
            concat!(simple_macro!(), r#"fn f() { let a = foo!(foo$0); }"#),
            "foo!(foo)",
        );
    }

    #[test]
    fn inline_macro_simple_case1() {
        check_assist(
            inline_macro,
            concat!(simple_macro!(), r#"fn f() { let result = foo$0!(foo); }"#),
            concat!(simple_macro!(), r#"fn f() { let result = true; }"#),
        );
    }

    #[test]
    fn inline_macro_simple_case2() {
        check_assist(
            inline_macro,
            concat!(simple_macro!(), r#"fn f() { let result = foo$0!(); }"#),
            concat!(simple_macro!(), r#"fn f() { let result = false; }"#),
        );
    }

    #[test]
    fn inline_macro_simple_not_applicable() {
        check_assist_not_applicable(
            inline_macro,
            concat!(simple_macro!(), r#"fn f() { let result$0 = foo!(foo); }"#),
        );
    }

    #[test]
    fn inline_macro_simple_not_applicable_broken_macro() {
        // FIXME: This is a bug. The macro should not expand, but it's
        // the same behaviour as the "Expand Macro Recursively" commmand
        // so it's presumably OK for the time being.
        check_assist(
            inline_macro,
            concat!(simple_macro!(), r#"fn f() { let result = foo$0!(asdfasdf); }"#),
            concat!(simple_macro!(), r#"fn f() { let result = true; }"#),
        );
    }

    #[test]
    fn inline_macro_double_case1() {
        check_assist(
            inline_macro,
            concat!(double_macro!(), r#"fn f() { let result = foo$0!(bar); }"#),
            concat!(double_macro!(), r#"fn f() { let result = bar!(bar); }"#),
        );
    }

    #[test]
    fn inline_macro_double_case2() {
        check_assist(
            inline_macro,
            concat!(double_macro!(), r#"fn f() { let result = foo$0!(asdf); }"#),
            concat!(double_macro!(), r#"fn f() { let result = bar!(asdf); }"#),
        );
    }

    #[test]
    fn inline_macro_complex_case1() {
        check_assist(
            inline_macro,
            concat!(complex_macro!(), r#"fn f() { let result = num!(+ +$0 + - +); }"#),
            concat!(complex_macro!(), r#"fn f() { let result = 1+num!(+ + - +); }"#),
        );
    }

    #[test]
    fn inline_macro_complex_case2() {
        check_assist(
            inline_macro,
            concat!(complex_macro!(), r#"fn f() { let result = n$0um!(- + + - +); }"#),
            concat!(complex_macro!(), r#"fn f() { let result = -1+num!(+ + - +); }"#),
        );
    }

    #[test]
    fn inline_macro_recursive_macro() {
        check_assist(
            inline_macro,
            r#"
macro_rules! foo {
  () => {foo!()}
}
fn f() { let result = foo$0!(); }
"#,
            r#"
macro_rules! foo {
  () => {foo!()}
}
fn f() { let result = foo!(); }
"#,
        );
    }

    #[test]
    fn inline_macro_unknown_macro() {
        check_assist_not_applicable(
            inline_macro,
            r#"
fn f() { let result = foo$0!(); }
"#,
        );
    }

    #[test]
    fn inline_macro_function_call_not_applicable() {
        check_assist_not_applicable(
            inline_macro,
            r#"
fn f() { let result = foo$0(); }
"#,
        );
    }

    #[test]
    fn inline_macro_with_whitespace() {
        check_assist(
            inline_macro,
            r#"
macro_rules! whitespace {
    () => {
        if true {}
    };
}
fn f() { whitespace$0!(); }
"#,
            r#"
macro_rules! whitespace {
    () => {
        if true {}
    };
}
fn f() { if true{}; }
"#,
        )
    }
}