use syntax::{
    ast::{self, AstNode},
    SyntaxElement, 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 is_leaf = macro_call.syntax().next_sibling().is_none();
    let macro_text_with_brackets = macro_call.token_tree()?.syntax().text();
    let slice_index = if is_leaf || !needs_parentheses_around_macro_contents(contents) {
        TextRange::new(TextSize::of('('), macro_text_with_brackets.len() - TextSize::of(')'))
    } else {
        // leave parenthesis around macro contents to preserve the semantics
        TextRange::up_to(macro_text_with_brackets.len())
    };
    Some(macro_text_with_brackets.slice(slice_index).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 macro_contents_kind_not_in_brackets = Vec::with_capacity(macro_contents.len());

    let mut first_bracket_in_macro = None;
    let mut unpaired_brackets_in_contents = Vec::new();
    for element in macro_contents {
        match element.kind() {
            T!['('] | T!['['] | T!['{'] => {
                if let None = first_bracket_in_macro {
                    first_bracket_in_macro = Some(element.clone())
                }
                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;
                }
            }
            other_kind => {
                if unpaired_brackets_in_contents.is_empty() {
                    macro_contents_kind_not_in_brackets.push(other_kind);
                }
            }
        }
    }

    !unpaired_brackets_in_contents.is_empty()
        || matches!(first_bracket_in_macro, Some(bracket) if bracket.kind() != T!['('])
        || macro_contents_kind_not_in_brackets
            .into_iter()
            .any(|macro_contents_kind| macro_contents_kind.is_punct())
}

#[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) {
        // ...
    }
}
",
        );
    }

    #[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"#);
    }

    #[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);
}"#,
        );
    }
}