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// Copyright (C) 2023 Benjamin Stürz
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
#![allow(dead_code)]
use proc_macro::TokenStream;
use proc_macro2::{Ident, Group};
use syn::{Token, LitInt, parse_macro_input, ExprBlock, LitFloat};
use quote::ToTokens;

mod parse;
mod gen;

struct CSS(Vec<Rule>);

struct Rule {
    selector: Selector,
    group: Group,
    declarations: Declarations,
}

enum Selector {
    Simple {
        ident: Option<CSSIdent>,
        class: Option<(Token![.], CSSIdent)>,
        id: Option<(Token![#], CSSIdent)>,
    },
    Colon {
        colon: Token![:],
        ident: CSSIdent,
        arg: Option<(Group, Value)>,
    },
    Sub {
        left: Box<Selector>,
        right: Box<Selector>,
    },
    Gt {
        left: Box<Selector>,
        gt: Token![>],
        right: Box<Selector>,
    },
    Plus {
        left: Box<Selector>,
        plus: Token![+],
        right: Box<Selector>,
    },
    Tilde {
        left: Box<Selector>,
        tilde: Token![~],
        right: Box<Selector>,
    },
    Comma {
        left: Box<Selector>,
        comma: Token![,],
        right: Box<Selector>,
    },
}

struct Declarations(Vec<Declaration>);

struct Declaration {
    ident: CSSIdent,
    colon: Token![:],
    value: Vec<Value>,
    semicolon: Token![;],
}

enum Value {
    ColorCode { pound: Token![#], value: LitInt },
    Ident(CSSIdent),
    Int(LitInt),
    Float(LitFloat),
    IntPerc(LitInt, Token![%]),
    FloatPerc(LitFloat, Token![%]),
    Function { ident: CSSIdent, group: Group, args: Args },
    Block(ExprBlock),
}

struct Args(Vec<Value>);

struct CSSIdent(Vec<CSSIdentSegment>);

enum CSSIdentSegment {
    Ident(Ident),
    Minus(Token![-]),
}

#[proc_macro]
pub fn css(input: TokenStream) -> TokenStream {
    parse_macro_input!(input as CSS).into_token_stream().into()
}

#[proc_macro]
pub fn css_rule(input: TokenStream) -> TokenStream {
    parse_macro_input!(input as Rule).into_token_stream().into()
}

#[proc_macro]
pub fn css_value(input: TokenStream) -> TokenStream {
    parse_macro_input!(input as Value).into_token_stream().into()
}