use crate::{Parser, Spanned};
use source_span::Span;
use trilogy_scanner::Token;
use trilogy_scanner::TokenType::{self, DocInner, DocOuter};

/// A documentation comment, either inner or outer.
///
/// ```trilogy
/// ## Hello this is a doc comment.
/// ## It may be multiple lines long.
/// ```
#[derive(Clone, Debug)]
pub struct Documentation {
    pub tokens: Vec<Token>,
    pub span: Span,
}

impl Spanned for Documentation {
    fn span(&self) -> Span {
        self.span
    }
}

impl Documentation {
    fn parse(parser: &mut Parser, token_type: TokenType) -> Option<Self> {
        let mut tokens = vec![];

        while let Ok(token) = parser.expect(token_type) {
            tokens.push(token);
        }
        if tokens.is_empty() {
            return None;
        }

        Some(Self {
            span: tokens
                .iter()
                .map(|token| token.span)
                .reduce(|l, r| l.union(r))
                .unwrap(),
            tokens,
        })
    }

    pub(crate) fn parse_inner(parser: &mut Parser) -> Option<Self> {
        Self::parse(parser, DocInner)
    }

    pub(crate) fn parse_outer(parser: &mut Parser) -> Option<Self> {
        Self::parse(parser, DocOuter)
    }
}

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

    test_parse!(documentation_inner: "#! hello\n" => Documentation::parse_inner => Documentation { .. });
    test_parse!(documentation_inner_multiline: "#! hello\n#! world\n" => Documentation::parse_inner => Documentation { .. });
    test_parse!(documentation_inner_gaps: "#! hello\n\n#! world\n" => Documentation::parse_inner => Documentation { .. });

    test_parse!(documentation_outer: "## hello\n" => Documentation::parse_outer => Documentation { .. });
    test_parse!(documentation_outer_multiline: "## hello\n## world\n" => Documentation::parse_outer => Documentation { .. });
    test_parse!(documentation_outer_gaps: "## hello\n\n## world\n" => Documentation::parse_outer => Documentation { .. });
}