//! Abstract Syntax Tree, layered on top of untyped `SyntaxNode`s

mod generated;
mod traits;
mod tokens;
mod extensions;
mod expr_extensions;
pub mod edit;
pub mod make;

use std::marker::PhantomData;

use crate::{
    syntax_node::{
        NodeOrToken, SyntaxElement, SyntaxElementChildren, SyntaxNode, SyntaxNodeChildren,
        SyntaxToken,
    },
    SmolStr, SyntaxKind,
};

pub use self::{
    expr_extensions::{ArrayExprKind, BinOp, ElseBranch, LiteralKind, PrefixOp, RangeOp},
    extensions::{
        AttrKind, FieldKind, PathSegmentKind, SelfParamKind, SlicePatComponents, StructKind,
        TypeBoundKind, VisibilityKind,
    },
    generated::*,
    tokens::*,
    traits::*,
};

/// The main trait to go from untyped `SyntaxNode`  to a typed ast. The
/// conversion itself has zero runtime cost: ast and syntax nodes have exactly
/// the same representation: a pointer to the tree root and a pointer to the
/// node itself.
pub trait AstNode: AstElement {
    fn can_cast(kind: SyntaxKind) -> bool
    where
        Self: Sized;

    fn cast_or_return(syntax: SyntaxNode) -> Result<Self, SyntaxNode>
    where
        Self: Sized;

    fn cast(syntax: SyntaxNode) -> Option<Self>
    where
        Self: Sized,
    {
        <Self as AstNode>::cast_or_return(syntax).ok()
    }

    fn syntax(&self) -> &SyntaxNode;
    fn into_syntax(self) -> SyntaxNode;
}

#[test]
fn assert_ast_is_object_safe() {
    fn _f(_: &dyn AstNode, _: &dyn NameOwner) {}
}

/// Like `AstNode`, but wraps tokens rather than interior nodes.
pub trait AstToken: AstElement {
    fn can_cast(token: SyntaxKind) -> bool
    where
        Self: Sized;

    fn cast_or_return(syntax: SyntaxToken) -> Result<Self, SyntaxToken>
    where
        Self: Sized;

    fn cast(syntax: SyntaxToken) -> Option<Self>
    where
        Self: Sized,
    {
        <Self as AstToken>::cast_or_return(syntax).ok()
    }

    fn syntax(&self) -> &SyntaxToken;
    fn into_syntax(self) -> SyntaxToken;

    fn text(&self) -> &SmolStr {
        self.syntax().text()
    }
}

/// Like `AstNode`, but wraps either nodes or tokens rather than interior nodes.
pub trait AstElement: std::fmt::Display {
    fn can_cast_element(kind: SyntaxKind) -> bool
    where
        Self: Sized;

    fn cast_or_return_element(syntax: SyntaxElement) -> Result<Self, SyntaxElement>
    where
        Self: Sized;

    fn cast_element(syntax: SyntaxElement) -> Option<Self>
    where
        Self: Sized,
    {
        <Self as AstElement>::cast_or_return_element(syntax).ok()
    }

    fn syntax_element(&self) -> NodeOrToken<&SyntaxNode, &SyntaxToken>;
    fn into_syntax_element(self) -> SyntaxElement;
}

/// An iterator over `SyntaxNode` children of a particular AST type.
#[derive(Debug, Clone)]
pub struct AstChildren<N> {
    inner: SyntaxNodeChildren,
    ph: PhantomData<N>,
}

impl<N> AstChildren<N> {
    fn new(parent: &SyntaxNode) -> Self {
        AstChildren { inner: parent.children(), ph: PhantomData }
    }
}

impl<N: AstNode> Iterator for AstChildren<N> {
    type Item = N;
    fn next(&mut self) -> Option<N> {
        self.inner.by_ref().find_map(N::cast)
    }
}

fn child_opt<P: AstNode + ?Sized, C: AstNode>(parent: &P) -> Option<C> {
    children(parent).next()
}

fn children<P: AstNode + ?Sized, C: AstNode>(parent: &P) -> AstChildren<C> {
    AstChildren::new(parent.syntax())
}

/// An iterator over `SyntaxToken` children of a particular AST type.
#[derive(Debug, Clone)]
pub struct AstChildTokens<N> {
    inner: SyntaxElementChildren,
    ph: PhantomData<N>,
}

impl<N> AstChildTokens<N> {
    fn new(parent: &SyntaxNode) -> Self {
        AstChildTokens { inner: parent.children_with_tokens(), ph: PhantomData }
    }
}

impl<N: AstToken> Iterator for AstChildTokens<N> {
    type Item = N;
    fn next(&mut self) -> Option<N> {
        self.inner.by_ref().filter_map(|x| x.into_token()).find_map(N::cast)
    }
}

fn child_token_opt<P: AstNode + ?Sized, C: AstToken>(parent: &P) -> Option<C> {
    child_tokens(parent).next()
}

fn child_tokens<P: AstNode + ?Sized, C: AstToken>(parent: &P) -> AstChildTokens<C> {
    AstChildTokens::new(parent.syntax())
}

/// An iterator over `SyntaxNode` children of a particular AST type.
#[derive(Debug, Clone)]
pub struct AstChildElements<N> {
    inner: SyntaxElementChildren,
    ph: PhantomData<N>,
}

impl<N> AstChildElements<N> {
    fn new(parent: &SyntaxNode) -> Self {
        AstChildElements { inner: parent.children_with_tokens(), ph: PhantomData }
    }
}

impl<N: AstElement> Iterator for AstChildElements<N> {
    type Item = N;
    fn next(&mut self) -> Option<N> {
        self.inner.by_ref().find_map(N::cast_element)
    }
}

#[allow(dead_code)]
fn child_element_opt<P: AstNode + ?Sized, C: AstElement>(parent: &P) -> Option<C> {
    child_elements(parent).next()
}

#[allow(dead_code)]
fn child_elements<P: AstNode + ?Sized, C: AstElement>(parent: &P) -> AstChildElements<C> {
    AstChildElements::new(parent.syntax())
}

#[test]
fn test_doc_comment_none() {
    let file = SourceFile::parse(
        r#"
        // non-doc
        mod foo {}
        "#,
    )
    .ok()
    .unwrap();
    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
    assert!(module.doc_comment_text().is_none());
}

#[test]
fn test_doc_comment_of_items() {
    let file = SourceFile::parse(
        r#"
        //! doc
        // non-doc
        mod foo {}
        "#,
    )
    .ok()
    .unwrap();
    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
    assert_eq!("doc", module.doc_comment_text().unwrap());
}

#[test]
fn test_doc_comment_of_statics() {
    let file = SourceFile::parse(
        r#"
        /// Number of levels
        static LEVELS: i32 = 0;
        "#,
    )
    .ok()
    .unwrap();
    let st = file.syntax().descendants().find_map(StaticDef::cast).unwrap();
    assert_eq!("Number of levels", st.doc_comment_text().unwrap());
}

#[test]
fn test_doc_comment_preserves_indents() {
    let file = SourceFile::parse(
        r#"
        /// doc1
        /// ```
        /// fn foo() {
        ///     // ...
        /// }
        /// ```
        mod foo {}
        "#,
    )
    .ok()
    .unwrap();
    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
    assert_eq!("doc1\n```\nfn foo() {\n    // ...\n}\n```", module.doc_comment_text().unwrap());
}

#[test]
fn test_doc_comment_preserves_newlines() {
    let file = SourceFile::parse(
        r#"
        /// this
        /// is
        /// mod
        /// foo
        mod foo {}
        "#,
    )
    .ok()
    .unwrap();
    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
    assert_eq!("this\nis\nmod\nfoo", module.doc_comment_text().unwrap());
}

#[test]
fn test_doc_comment_single_line_block_strips_suffix() {
    let file = SourceFile::parse(
        r#"
        /** this is mod foo*/
        mod foo {}
        "#,
    )
    .ok()
    .unwrap();
    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
    assert_eq!("this is mod foo", module.doc_comment_text().unwrap());
}

#[test]
fn test_doc_comment_single_line_block_strips_suffix_whitespace() {
    let file = SourceFile::parse(
        r#"
        /** this is mod foo */
        mod foo {}
        "#,
    )
    .ok()
    .unwrap();
    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
    assert_eq!("this is mod foo ", module.doc_comment_text().unwrap());
}

#[test]
fn test_doc_comment_multi_line_block_strips_suffix() {
    let file = SourceFile::parse(
        r#"
        /**
        this
        is
        mod foo
        */
        mod foo {}
        "#,
    )
    .ok()
    .unwrap();
    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
    assert_eq!(
        "        this\n        is\n        mod foo\n        ",
        module.doc_comment_text().unwrap()
    );
}

#[test]
fn test_comments_preserve_trailing_whitespace() {
    let file = SourceFile::parse(
        "\n/// Representation of a Realm.   \n/// In the specification these are called Realm Records.\nstruct Realm {}",
    )
    .ok()
    .unwrap();
    let def = file.syntax().descendants().find_map(StructDef::cast).unwrap();
    assert_eq!(
        "Representation of a Realm.   \nIn the specification these are called Realm Records.",
        def.doc_comment_text().unwrap()
    );
}

#[test]
fn test_where_predicates() {
    fn assert_bound(text: &str, bound: Option<TypeBound>) {
        assert_eq!(text, bound.unwrap().syntax().text().to_string());
    }

    let file = SourceFile::parse(
        r#"
fn foo()
where
   T: Clone + Copy + Debug + 'static,
   'a: 'b + 'c,
   Iterator::Item: 'a + Debug,
   Iterator::Item: Debug + 'a,
   <T as Iterator>::Item: Debug + 'a,
   for<'a> F: Fn(&'a str)
{}
        "#,
    )
    .ok()
    .unwrap();
    let where_clause = file.syntax().descendants().find_map(WhereClause::cast).unwrap();

    let mut predicates = where_clause.predicates();

    let pred = predicates.next().unwrap();
    let mut bounds = pred.type_bound_list().unwrap().bounds();

    assert_eq!("T", pred.type_ref().unwrap().syntax().text().to_string());
    assert_bound("Clone", bounds.next());
    assert_bound("Copy", bounds.next());
    assert_bound("Debug", bounds.next());
    assert_bound("'static", bounds.next());

    let pred = predicates.next().unwrap();
    let mut bounds = pred.type_bound_list().unwrap().bounds();

    assert_eq!("'a", pred.lifetime_token().unwrap().text());

    assert_bound("'b", bounds.next());
    assert_bound("'c", bounds.next());

    let pred = predicates.next().unwrap();
    let mut bounds = pred.type_bound_list().unwrap().bounds();

    assert_eq!("Iterator::Item", pred.type_ref().unwrap().syntax().text().to_string());
    assert_bound("'a", bounds.next());

    let pred = predicates.next().unwrap();
    let mut bounds = pred.type_bound_list().unwrap().bounds();

    assert_eq!("Iterator::Item", pred.type_ref().unwrap().syntax().text().to_string());
    assert_bound("Debug", bounds.next());
    assert_bound("'a", bounds.next());

    let pred = predicates.next().unwrap();
    let mut bounds = pred.type_bound_list().unwrap().bounds();

    assert_eq!("<T as Iterator>::Item", pred.type_ref().unwrap().syntax().text().to_string());
    assert_bound("Debug", bounds.next());
    assert_bound("'a", bounds.next());

    let pred = predicates.next().unwrap();
    let mut bounds = pred.type_bound_list().unwrap().bounds();

    assert_eq!("for<'a> F", pred.type_ref().unwrap().syntax().text().to_string());
    assert_bound("Fn(&'a str)", bounds.next());
}