use syntax::{
    ast::{self, AstNode},
    SyntaxElement, SyntaxKind, TextRange, TextSize, T,
};

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

// Assist: remove_dbg
//
// Removes `dbg!()` macro call.
//
// ```
// fn main() {
//     <|>dbg!(92);
// }
// ```
// ->
// ```
// fn main() {
//     92;
// }
// ```
pub(crate) fn remove_dbg(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
    let macro_call = ctx.find_node_at_offset::<ast::MacroCall>()?;
    let new_contents = adjusted_macro_contents(&macro_call)?;

    let macro_text_range = macro_call.syntax().text_range();
    let macro_end = if macro_call.semicolon_token().is_some() {
        macro_text_range.end() - TextSize::of(';')
    } else {
        macro_text_range.end()
    };

    acc.add(
        AssistId("remove_dbg", AssistKind::Refactor),
        "Remove dbg!()",
        macro_text_range,
        |builder| {
            builder.replace(TextRange::new(macro_text_range.start(), macro_end), new_contents);
        },
    )
}

fn adjusted_macro_contents(macro_call: &ast::MacroCall) -> Option<String> {
    let contents = get_valid_macrocall_contents(&macro_call, "dbg")?;
    let macro_text_with_brackets = macro_call.token_tree()?.syntax().text();
    let macro_text_in_brackets = macro_text_with_brackets.slice(TextRange::new(
        TextSize::of('('),
        macro_text_with_brackets.len() - TextSize::of(')'),
    ));

    let is_leaf = macro_call.syntax().next_sibling().is_none();
    Some(if !is_leaf && needs_parentheses_around_macro_contents(contents) {
        format!("({})", macro_text_in_brackets)
    } else {
        macro_text_in_brackets.to_string()
    })
}

/// Verifies that the given macro_call actually matches the given name
/// and contains proper ending tokens, then returns the contents between the ending tokens
fn get_valid_macrocall_contents(
    macro_call: &ast::MacroCall,
    macro_name: &str,
) -> Option<Vec<SyntaxElement>> {
    let path = macro_call.path()?;
    let name_ref = path.segment()?.name_ref()?;

    // Make sure it is actually a dbg-macro call, dbg followed by !
    let excl = path.syntax().next_sibling_or_token()?;
    if name_ref.text() != macro_name || excl.kind() != T![!] {
        return None;
    }

    let mut children_with_tokens = macro_call.token_tree()?.syntax().children_with_tokens();
    let first_child = children_with_tokens.next()?;
    let mut contents_between_brackets = children_with_tokens.collect::<Vec<_>>();
    let last_child = contents_between_brackets.pop()?;

    if contents_between_brackets.is_empty() {
        None
    } else {
        match (first_child.kind(), last_child.kind()) {
            (T!['('], T![')']) | (T!['['], T![']']) | (T!['{'], T!['}']) => {
                Some(contents_between_brackets)
            }
            _ => None,
        }
    }
}

fn needs_parentheses_around_macro_contents(macro_contents: Vec<SyntaxElement>) -> bool {
    if macro_contents.len() < 2 {
        return false;
    }
    let mut unpaired_brackets_in_contents = Vec::new();
    for element in macro_contents {
        match element.kind() {
            T!['('] | T!['['] | T!['{'] => unpaired_brackets_in_contents.push(element),
            T![')'] => {
                if !matches!(unpaired_brackets_in_contents.pop(), Some(correct_bracket) if correct_bracket.kind() == T!['('])
                {
                    return true;
                }
            }
            T![']'] => {
                if !matches!(unpaired_brackets_in_contents.pop(), Some(correct_bracket) if correct_bracket.kind() == T!['['])
                {
                    return true;
                }
            }
            T!['}'] => {
                if !matches!(unpaired_brackets_in_contents.pop(), Some(correct_bracket) if correct_bracket.kind() == T!['{'])
                {
                    return true;
                }
            }
            symbol_kind => {
                let symbol_not_in_bracket = unpaired_brackets_in_contents.is_empty();
                if symbol_not_in_bracket
                    // paths
                    && symbol_kind != SyntaxKind::COLON
                    // field/method access
                    && symbol_kind != SyntaxKind::DOT
                    // try operator
                    && symbol_kind != SyntaxKind::QUESTION
                    && (symbol_kind.is_punct() || symbol_kind == SyntaxKind::AS_KW)
                {
                    return true;
                }
            }
        }
    }
    !unpaired_brackets_in_contents.is_empty()
}

#[cfg(test)]
mod tests {
    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};

    use super::*;

    #[test]
    fn test_remove_dbg() {
        check_assist(remove_dbg, "<|>dbg!(1 + 1)", "1 + 1");

        check_assist(remove_dbg, "dbg!<|>((1 + 1))", "(1 + 1)");

        check_assist(remove_dbg, "dbg!(1 <|>+ 1)", "1 + 1");

        check_assist(remove_dbg, "let _ = <|>dbg!(1 + 1)", "let _ = 1 + 1");

        check_assist(
            remove_dbg,
            "
fn foo(n: usize) {
    if let Some(_) = dbg!(n.<|>checked_sub(4)) {
        // ...
    }
}
",
            "
fn foo(n: usize) {
    if let Some(_) = n.checked_sub(4) {
        // ...
    }
}
",
        );

        check_assist(remove_dbg, "<|>dbg!(Foo::foo_test()).bar()", "Foo::foo_test().bar()");
    }

    #[test]
    fn test_remove_dbg_with_brackets_and_braces() {
        check_assist(remove_dbg, "dbg![<|>1 + 1]", "1 + 1");
        check_assist(remove_dbg, "dbg!{<|>1 + 1}", "1 + 1");
    }

    #[test]
    fn test_remove_dbg_not_applicable() {
        check_assist_not_applicable(remove_dbg, "<|>vec![1, 2, 3]");
        check_assist_not_applicable(remove_dbg, "<|>dbg(5, 6, 7)");
        check_assist_not_applicable(remove_dbg, "<|>dbg!(5, 6, 7");
    }

    #[test]
    fn test_remove_dbg_target() {
        check_assist_target(
            remove_dbg,
            "
fn foo(n: usize) {
    if let Some(_) = dbg!(n.<|>checked_sub(4)) {
        // ...
    }
}
",
            "dbg!(n.checked_sub(4))",
        );
    }

    #[test]
    fn test_remove_dbg_keep_semicolon() {
        // https://github.com/rust-analyzer/rust-analyzer/issues/5129#issuecomment-651399779
        // not quite though
        // adding a comment at the end of the line makes
        // the ast::MacroCall to include the semicolon at the end
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(1 * 20); // needless comment"#,
            r#"let res = 1 * 20; // needless comment"#,
        );
    }

    #[test]
    fn remove_dbg_from_non_leaf_simple_expression() {
        check_assist(
            remove_dbg,
            "
fn main() {
    let mut a = 1;
    while dbg!<|>(a) < 10000 {
        a += 1;
    }
}
",
            "
fn main() {
    let mut a = 1;
    while a < 10000 {
        a += 1;
    }
}
",
        );
    }

    #[test]
    fn test_remove_dbg_keep_expression() {
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(a + b).foo();"#,
            r#"let res = (a + b).foo();"#,
        );

        check_assist(remove_dbg, r#"let res = <|>dbg!(2 + 2) * 5"#, r#"let res = (2 + 2) * 5"#);
        check_assist(remove_dbg, r#"let res = <|>dbg![2 + 2] * 5"#, r#"let res = (2 + 2) * 5"#);
    }

    #[test]
    fn test_remove_dbg_method_chaining() {
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(foo().bar()).baz();"#,
            r#"let res = foo().bar().baz();"#,
        );
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(foo.bar()).baz();"#,
            r#"let res = foo.bar().baz();"#,
        );
    }

    #[test]
    fn test_remove_dbg_field_chaining() {
        check_assist(remove_dbg, r#"let res = <|>dbg!(foo.bar).baz;"#, r#"let res = foo.bar.baz;"#);
    }

    #[test]
    fn test_remove_dbg_from_inside_fn() {
        check_assist_target(
            remove_dbg,
            r#"
fn square(x: u32) -> u32 {
    x * x
}

fn main() {
    let x = square(dbg<|>!(5 + 10));
    println!("{}", x);
}"#,
            "dbg!(5 + 10)",
        );

        check_assist(
            remove_dbg,
            r#"
fn square(x: u32) -> u32 {
    x * x
}

fn main() {
    let x = square(dbg<|>!(5 + 10));
    println!("{}", x);
}"#,
            r#"
fn square(x: u32) -> u32 {
    x * x
}

fn main() {
    let x = square(5 + 10);
    println!("{}", x);
}"#,
        );
    }

    #[test]
    fn test_remove_dbg_try_expr() {
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(result?).foo();"#,
            r#"let res = result?.foo();"#,
        );
    }

    #[test]
    fn test_remove_dbg_await_expr() {
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(fut.await).foo();"#,
            r#"let res = fut.await.foo();"#,
        );
    }

    #[test]
    fn test_remove_dbg_as_cast() {
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(3 as usize).foo();"#,
            r#"let res = (3 as usize).foo();"#,
        );
    }

    #[test]
    fn test_remove_dbg_index_expr() {
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(array[3]).foo();"#,
            r#"let res = array[3].foo();"#,
        );
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(tuple.3).foo();"#,
            r#"let res = tuple.3.foo();"#,
        );
    }

    #[test]
    #[ignore] // FIXME: we encounter SyntaxKind::DOT instead of SyntaxKind::DOT2 causing this to fail
    fn test_remove_dbg_range_expr() {
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(foo..bar).foo();"#,
            r#"let res = (foo..bar).foo();"#,
        );
        check_assist(
            remove_dbg,
            r#"let res = <|>dbg!(foo..=bar).foo();"#,
            r#"let res = (foo..=bar).foo();"#,
        );
    }
}