use crate::syntax::{LinkedNode, SyntaxKind};

/// Syntax highlighting categories.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub enum Category {
    /// A line or block comment.
    Comment,
    /// Punctuation in code.
    Punctuation,
    /// An escape sequence, shorthand or symbol notation.
    Escape,
    /// Strong markup.
    Strong,
    /// Emphasized markup.
    Emph,
    /// A hyperlink.
    Link,
    /// Raw text.
    Raw,
    /// A label.
    Label,
    /// A reference to a label.
    Ref,
    /// A section heading.
    Heading,
    /// A marker of a list, enumeration, or term list.
    ListMarker,
    /// A term in a term list.
    ListTerm,
    /// The delimiters of a math formula.
    MathDelimiter,
    /// An operator with special meaning in a math formula.
    MathOperator,
    /// A keyword.
    Keyword,
    /// An operator in code.
    Operator,
    /// A numeric literal.
    Number,
    /// A string literal.
    String,
    /// A function or method name.
    Function,
    /// An interpolated variable in markup or math.
    Interpolated,
    /// A syntax error.
    Error,
}

impl Category {
    /// Return the recommended TextMate grammar scope for the given highlighting
    /// category.
    pub fn tm_scope(&self) -> &'static str {
        match self {
            Self::Comment => "comment.typst",
            Self::Punctuation => "punctuation.typst",
            Self::Escape => "constant.character.escape.typst",
            Self::Strong => "markup.bold.typst",
            Self::Emph => "markup.italic.typst",
            Self::Link => "markup.underline.link.typst",
            Self::Raw => "markup.raw.typst",
            Self::MathDelimiter => "punctuation.definition.math.typst",
            Self::MathOperator => "keyword.operator.math.typst",
            Self::Heading => "markup.heading.typst",
            Self::ListMarker => "punctuation.definition.list.typst",
            Self::ListTerm => "markup.list.term.typst",
            Self::Label => "entity.name.label.typst",
            Self::Ref => "markup.other.reference.typst",
            Self::Keyword => "keyword.typst",
            Self::Operator => "keyword.operator.typst",
            Self::Number => "constant.numeric.typst",
            Self::String => "string.quoted.double.typst",
            Self::Function => "entity.name.function.typst",
            Self::Interpolated => "meta.interpolation.typst",
            Self::Error => "invalid.typst",
        }
    }
}

/// Highlight a linked syntax node.
///
/// Produces a highlighting category or `None` if the node should not be
/// highlighted.
pub fn highlight(node: &LinkedNode) -> Option<Category> {
    match node.kind() {
        SyntaxKind::LineComment => Some(Category::Comment),
        SyntaxKind::BlockComment => Some(Category::Comment),
        SyntaxKind::Space { .. } => None,

        SyntaxKind::LeftBrace => Some(Category::Punctuation),
        SyntaxKind::RightBrace => Some(Category::Punctuation),
        SyntaxKind::LeftBracket => Some(Category::Punctuation),
        SyntaxKind::RightBracket => Some(Category::Punctuation),
        SyntaxKind::LeftParen => Some(Category::Punctuation),
        SyntaxKind::RightParen => Some(Category::Punctuation),
        SyntaxKind::Comma => Some(Category::Punctuation),
        SyntaxKind::Semicolon => Some(Category::Punctuation),
        SyntaxKind::Colon => Some(Category::Punctuation),
        SyntaxKind::Star => match node.parent_kind() {
            Some(SyntaxKind::Strong) => None,
            _ => Some(Category::Operator),
        },
        SyntaxKind::Underscore => match node.parent_kind() {
            Some(SyntaxKind::Script) => Some(Category::MathOperator),
            _ => None,
        },
        SyntaxKind::Dollar => Some(Category::MathDelimiter),
        SyntaxKind::Plus => Some(match node.parent_kind() {
            Some(SyntaxKind::EnumItem) => Category::ListMarker,
            _ => Category::Operator,
        }),
        SyntaxKind::Minus => Some(match node.parent_kind() {
            Some(SyntaxKind::ListItem) => Category::ListMarker,
            _ => Category::Operator,
        }),
        SyntaxKind::Slash => Some(match node.parent_kind() {
            Some(SyntaxKind::TermItem) => Category::ListMarker,
            Some(SyntaxKind::Frac) => Category::MathOperator,
            _ => Category::Operator,
        }),
        SyntaxKind::Hat => Some(Category::MathOperator),
        SyntaxKind::Amp => Some(Category::MathOperator),
        SyntaxKind::Dot => Some(Category::Punctuation),
        SyntaxKind::Eq => match node.parent_kind() {
            Some(SyntaxKind::Heading) => None,
            _ => Some(Category::Operator),
        },
        SyntaxKind::EqEq => Some(Category::Operator),
        SyntaxKind::ExclEq => Some(Category::Operator),
        SyntaxKind::Lt => Some(Category::Operator),
        SyntaxKind::LtEq => Some(Category::Operator),
        SyntaxKind::Gt => Some(Category::Operator),
        SyntaxKind::GtEq => Some(Category::Operator),
        SyntaxKind::PlusEq => Some(Category::Operator),
        SyntaxKind::HyphEq => Some(Category::Operator),
        SyntaxKind::StarEq => Some(Category::Operator),
        SyntaxKind::SlashEq => Some(Category::Operator),
        SyntaxKind::Dots => Some(Category::Operator),
        SyntaxKind::Arrow => Some(Category::Operator),

        SyntaxKind::Not => Some(Category::Keyword),
        SyntaxKind::And => Some(Category::Keyword),
        SyntaxKind::Or => Some(Category::Keyword),
        SyntaxKind::None => Some(Category::Keyword),
        SyntaxKind::Auto => Some(Category::Keyword),
        SyntaxKind::Let => Some(Category::Keyword),
        SyntaxKind::Set => Some(Category::Keyword),
        SyntaxKind::Show => Some(Category::Keyword),
        SyntaxKind::If => Some(Category::Keyword),
        SyntaxKind::Else => Some(Category::Keyword),
        SyntaxKind::For => Some(Category::Keyword),
        SyntaxKind::In => Some(Category::Keyword),
        SyntaxKind::While => Some(Category::Keyword),
        SyntaxKind::Break => Some(Category::Keyword),
        SyntaxKind::Continue => Some(Category::Keyword),
        SyntaxKind::Return => Some(Category::Keyword),
        SyntaxKind::Import => Some(Category::Keyword),
        SyntaxKind::Include => Some(Category::Keyword),
        SyntaxKind::From => Some(Category::Keyword),

        SyntaxKind::Markup { .. }
            if node.parent_kind() == Some(&SyntaxKind::TermItem)
                && node.next_sibling().as_ref().map(|v| v.kind())
                    == Some(&SyntaxKind::Colon) =>
        {
            Some(Category::ListTerm)
        }
        SyntaxKind::Markup { .. } => None,

        SyntaxKind::Text(_) => None,
        SyntaxKind::Linebreak => Some(Category::Escape),
        SyntaxKind::Escape(_) => Some(Category::Escape),
        SyntaxKind::Shorthand(_) => Some(Category::Escape),
        SyntaxKind::Symbol(_) => Some(Category::Escape),
        SyntaxKind::SmartQuote { .. } => None,
        SyntaxKind::Strong => Some(Category::Strong),
        SyntaxKind::Emph => Some(Category::Emph),
        SyntaxKind::Raw(_) => Some(Category::Raw),
        SyntaxKind::Link(_) => Some(Category::Link),
        SyntaxKind::Label(_) => Some(Category::Label),
        SyntaxKind::Ref(_) => Some(Category::Ref),
        SyntaxKind::Heading => Some(Category::Heading),
        SyntaxKind::ListItem => None,
        SyntaxKind::EnumItem => None,
        SyntaxKind::EnumNumbering(_) => Some(Category::ListMarker),
        SyntaxKind::TermItem => None,
        SyntaxKind::Math => None,
        SyntaxKind::Atom(_) => None,
        SyntaxKind::Script => None,
        SyntaxKind::Frac => None,
        SyntaxKind::AlignPoint => None,

        SyntaxKind::Ident(_) => match node.parent_kind() {
            Some(
                SyntaxKind::Markup { .. }
                | SyntaxKind::Math
                | SyntaxKind::Script
                | SyntaxKind::Frac,
            ) => Some(Category::Interpolated),
            Some(SyntaxKind::FuncCall) => Some(Category::Function),
            Some(SyntaxKind::MethodCall) if node.prev_sibling().is_some() => {
                Some(Category::Function)
            }
            Some(SyntaxKind::Closure) if node.prev_sibling().is_none() => {
                Some(Category::Function)
            }
            Some(SyntaxKind::SetRule) => Some(Category::Function),
            Some(SyntaxKind::ShowRule)
                if node.prev_sibling().as_ref().map(|v| v.kind())
                    == Some(&SyntaxKind::Show) =>
            {
                Some(Category::Function)
            }
            _ => None,
        },
        SyntaxKind::Bool(_) => Some(Category::Keyword),
        SyntaxKind::Int(_) => Some(Category::Number),
        SyntaxKind::Float(_) => Some(Category::Number),
        SyntaxKind::Numeric(_, _) => Some(Category::Number),
        SyntaxKind::Str(_) => Some(Category::String),
        SyntaxKind::CodeBlock => None,
        SyntaxKind::ContentBlock => None,
        SyntaxKind::Parenthesized => None,
        SyntaxKind::Array => None,
        SyntaxKind::Dict => None,
        SyntaxKind::Named => None,
        SyntaxKind::Keyed => None,
        SyntaxKind::Unary => None,
        SyntaxKind::Binary => None,
        SyntaxKind::FieldAccess => None,
        SyntaxKind::FuncCall => None,
        SyntaxKind::MethodCall => None,
        SyntaxKind::Args => None,
        SyntaxKind::Spread => None,
        SyntaxKind::Closure => None,
        SyntaxKind::Params => None,
        SyntaxKind::LetBinding => None,
        SyntaxKind::SetRule => None,
        SyntaxKind::ShowRule => None,
        SyntaxKind::Conditional => None,
        SyntaxKind::WhileLoop => None,
        SyntaxKind::ForLoop => None,
        SyntaxKind::ForPattern => None,
        SyntaxKind::ModuleImport => None,
        SyntaxKind::ImportItems => None,
        SyntaxKind::ModuleInclude => None,
        SyntaxKind::LoopBreak => None,
        SyntaxKind::LoopContinue => None,
        SyntaxKind::FuncReturn => None,

        SyntaxKind::Error(_, _) => Some(Category::Error),
    }
}

#[cfg(test)]
mod tests {
    use std::ops::Range;

    use super::*;
    use crate::syntax::Source;

    #[test]
    fn test_highlighting() {
        use Category::*;

        #[track_caller]
        fn test(text: &str, goal: &[(Range<usize>, Category)]) {
            let mut vec = vec![];
            let source = Source::detached(text);
            highlight_tree(&mut vec, &LinkedNode::new(source.root()));
            assert_eq!(vec, goal);
        }

        fn highlight_tree(tags: &mut Vec<(Range<usize>, Category)>, node: &LinkedNode) {
            if let Some(tag) = highlight(node) {
                tags.push((node.range(), tag));
            }

            for child in node.children() {
                highlight_tree(tags, &child);
            }
        }

        test("= *AB*", &[(0..6, Heading), (2..6, Strong)]);

        test(
            "#f(x + 1)",
            &[
                (0..2, Function),
                (2..3, Punctuation),
                (5..6, Operator),
                (7..8, Number),
                (8..9, Punctuation),
            ],
        );

        test(
            "#let f(x) = x",
            &[
                (0..4, Keyword),
                (5..6, Function),
                (6..7, Punctuation),
                (8..9, Punctuation),
                (10..11, Operator),
            ],
        );
    }
}
