use proc_macro2::Span as Span2;
use syn::{
    braced, parenthesized,
    parse::{Parse, ParseStream},
    punctuated::Punctuated,
    token, Ident, Path, Result, Token,
};

use super::{Menu, MenuEntry, MenuItem, MenuSection, Menus};

impl Parse for Menus {
    fn parse(input: ParseStream) -> Result<Self> {
        let items = input.call(Punctuated::parse_separated_nonempty)?;

        Ok(Menus { items })
    }
}

impl Parse for Menu {
    fn parse(input: ParseStream) -> Result<Self> {
        let name = input.parse()?;
        let _colon: Token![:] = input.parse()?;

        let braced_input;
        braced!(braced_input in input);

        let items = braced_input.call(Punctuated::parse_terminated)?;

        Ok(Menu { name, items })
    }
}

impl Parse for MenuEntry {
    fn parse(input: ParseStream) -> Result<Self> {
        let string = input.parse()?;
        let _arrow: Token![=>] = input.parse()?;
        let action_ty = input.call(Path::parse_mod_style)?;

        let value = if input.peek(token::Paren) {
            let paren_input;
            parenthesized!(paren_input in input);
            Some(paren_input.parse()?)
        } else {
            None
        };

        Ok(MenuEntry {
            string,
            action_ty,
            value,
        })
    }
}

impl Parse for MenuItem {
    fn parse(input: ParseStream) -> Result<Self> {
        Ok(if input.peek2(Token![!]) {
            input.parse().map(MenuItem::Section)?
        } else {
            input.parse().map(MenuItem::Entry)?
        })
    }
}

impl Parse for MenuSection {
    fn parse(input: ParseStream) -> Result<Self> {
        let name: Ident = input.parse()?;
        assert!(name == "section");
        let _excl: Token![!] = input.parse()?;

        let braced_input;
        braced!(braced_input in input);

        let items = braced_input.call(Punctuated::parse_terminated)?;
        let name = section_name();

        Ok(MenuSection { name, items })
    }
}

fn section_name() -> Ident {
    use std::sync::atomic::{AtomicU8, Ordering};
    static COUNTER: AtomicU8 = AtomicU8::new(0);

    let value = COUNTER.fetch_add(1, Ordering::Relaxed);

    Ident::new(&format!("_section_{}", value), Span2::call_site())
}