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use std::sync::Arc;

use gramatika::{Parse, ParseStreamer, Span, Spanned, Token as _};

use crate::{
	common::{AttributeList, TypeDecl},
	expr::Expr,
	token::{operator, punct, Token, TokenKind},
	ParseStream,
};

#[derive(Clone, DebugLisp)]
pub struct VarDecl {
	pub attributes: Option<AttributeList>,
	pub storage: Token,
	pub storage_qualifiers: Option<Arc<[Token]>>,
	pub name: Token,
	pub ty: Option<TypeDecl>,
	pub assignment: Option<Expr>,
	pub semicolon: Token,
}

impl Parse for VarDecl {
	type Stream = ParseStream;

	fn parse(input: &mut Self::Stream) -> gramatika::Result<Self> {
		let storage = input.consume_kind(TokenKind::Keyword)?;
		assert!(matches!(
			storage.as_matchable(),
			(TokenKind::Keyword, "let" | "const" | "var", _)
		));

		let storage_qualifiers = if input.check(operator![<]) {
			input.consume(operator![<])?;
			let mut qual = vec![input.consume_kind(TokenKind::Keyword)?];
			if input.check(punct![,]) {
				input.consume(punct![,])?;
				qual.push(input.consume_kind(TokenKind::Keyword)?);
			}
			input.consume(operator![>])?;
			Some(qual.into())
		} else {
			None
		};

		let name = input.consume_kind(TokenKind::Ident)?;
		let ty = if input.check(punct![:]) {
			Some(input.parse::<TypeDecl>()?)
		} else {
			None
		};

		let assignment = if input.check(operator![=]) {
			input.next().unwrap();

			Some(input.parse::<Expr>()?)
		} else {
			None
		};

		let semicolon = input.consume(punct![;])?;

		Ok(Self {
			attributes: None,
			storage,
			storage_qualifiers,
			name,
			ty,
			assignment,
			semicolon,
		})
	}
}

impl Spanned for VarDecl {
	fn span(&self) -> Span {
		self.storage.span().through(self.semicolon.span())
	}
}