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//! Various traits that are implemented by ast nodes.
//!
//! The implementations are usually trivial, and live in generated.rs
use either::Either;

use crate::{
    ast::{self, support, AstChildren, AstNode, AstToken},
    syntax_node::SyntaxElementChildren,
    SyntaxElement, SyntaxToken, T,
};

pub trait HasName: AstNode {
    fn name(&self) -> Option<ast::Name> {
        support::child(self.syntax())
    }
}

pub trait HasVisibility: AstNode {
    fn visibility(&self) -> Option<ast::Visibility> {
        support::child(self.syntax())
    }
}

pub trait HasLoopBody: AstNode {
    fn loop_body(&self) -> Option<ast::BlockExpr> {
        support::child(self.syntax())
    }

    fn label(&self) -> Option<ast::Label> {
        support::child(self.syntax())
    }
}

pub trait HasArgList: AstNode {
    fn arg_list(&self) -> Option<ast::ArgList> {
        support::child(self.syntax())
    }
}

pub trait HasModuleItem: AstNode {
    fn items(&self) -> AstChildren<ast::Item> {
        support::children(self.syntax())
    }
}

pub trait HasGenericParams: AstNode {
    fn generic_param_list(&self) -> Option<ast::GenericParamList> {
        support::child(self.syntax())
    }

    fn where_clause(&self) -> Option<ast::WhereClause> {
        support::child(self.syntax())
    }
}

pub trait HasTypeBounds: AstNode {
    fn type_bound_list(&self) -> Option<ast::TypeBoundList> {
        support::child(self.syntax())
    }

    fn colon_token(&self) -> Option<SyntaxToken> {
        support::token(self.syntax(), T![:])
    }
}

pub trait HasAttrs: AstNode {
    fn attrs(&self) -> AstChildren<ast::Attr> {
        support::children(self.syntax())
    }
    fn has_atom_attr(&self, atom: &str) -> bool {
        self.attrs().filter_map(|x| x.as_simple_atom()).any(|x| x == atom)
    }
}

pub trait HasDocComments: HasAttrs {
    fn doc_comments(&self) -> DocCommentIter {
        DocCommentIter { iter: self.syntax().children_with_tokens() }
    }
}

impl DocCommentIter {
    pub fn from_syntax_node(syntax_node: &ast::SyntaxNode) -> DocCommentIter {
        DocCommentIter { iter: syntax_node.children_with_tokens() }
    }

    #[cfg(test)]
    pub fn doc_comment_text(self) -> Option<String> {
        let docs = itertools::Itertools::join(
            &mut self.filter_map(|comment| comment.doc_comment().map(ToOwned::to_owned)),
            "\n",
        );
        if docs.is_empty() {
            None
        } else {
            Some(docs)
        }
    }
}

pub struct DocCommentIter {
    iter: SyntaxElementChildren,
}

impl Iterator for DocCommentIter {
    type Item = ast::Comment;
    fn next(&mut self) -> Option<ast::Comment> {
        self.iter.by_ref().find_map(|el| {
            el.into_token().and_then(ast::Comment::cast).filter(ast::Comment::is_doc)
        })
    }
}

pub struct AttrDocCommentIter {
    iter: SyntaxElementChildren,
}

impl AttrDocCommentIter {
    pub fn from_syntax_node(syntax_node: &ast::SyntaxNode) -> AttrDocCommentIter {
        AttrDocCommentIter { iter: syntax_node.children_with_tokens() }
    }
}

impl Iterator for AttrDocCommentIter {
    type Item = Either<ast::Attr, ast::Comment>;
    fn next(&mut self) -> Option<Self::Item> {
        self.iter.by_ref().find_map(|el| match el {
            SyntaxElement::Node(node) => ast::Attr::cast(node).map(Either::Left),
            SyntaxElement::Token(tok) => {
                ast::Comment::cast(tok).filter(ast::Comment::is_doc).map(Either::Right)
            }
        })
    }
}

impl<A: HasName, B: HasName> HasName for Either<A, B> {}