/*
 * MRustC - Rust Compiler
 * - By John Hodge (Mutabah/thePowersGang)
 *
 * expand/assert.cpp
 * - assert! built-in macro (1.29)
 */
#include <synext_macro.hpp>
#include <synext.hpp>   // for Expand_BareExpr
#include <parse/interpolated_fragment.hpp>
#include "../parse/ttstream.hpp"
#include "../parse/common.hpp"
#include "../parse/parseerror.hpp"

class CExpander_assert:
    public ExpandProcMacro
{
    ::std::unique_ptr<TokenStream> expand(const Span& sp, const ::AST::Crate& crate, const ::std::string& ident, const TokenTree& tt, AST::Module& mod) override
    {
        Token   tok;

        auto lex = TTStream(sp, tt);
        lex.parse_state().module = &mod;
        if( ident != "" )
            ERROR(sp, E0000, "format_args! doesn't take an ident");

        // assertion condition
        auto n = Parse_Expr0(lex);
        ASSERT_BUG(sp, n, "No expression returned");

        ::std::vector<TokenTree> toks;

        toks.push_back( Token(TOK_RWORD_IF) );

        GET_TOK(tok, lex);
        if( tok == TOK_COMMA )
        {
            toks.push_back( Token(InterpolatedFragment(InterpolatedFragment::EXPR, n.release())) );
            toks.push_back( Token(TOK_BRACE_OPEN) );
            // User-provided message
            toks.push_back( Token(TOK_IDENT, "panic") );
            toks.push_back( Token(TOK_EXCLAM) );
            toks.push_back( Token(TOK_PAREN_OPEN) );
            while(lex.lookahead(0) != TOK_EOF )
            {
                toks.push_back( Token(InterpolatedFragment(InterpolatedFragment::EXPR, Parse_Expr0(lex).release())) );
                if( lex.lookahead(0) != TOK_COMMA )
                    break;
                GET_CHECK_TOK(tok, lex, TOK_COMMA);
                toks.push_back( Token(TOK_COMMA) );
            }
            GET_CHECK_TOK(tok, lex, TOK_EOF);
            toks.push_back( Token(TOK_PAREN_CLOSE) );
        }
        else if( tok == TOK_EOF )
        {
            ::std::stringstream ss;
            ss << "assertion failed: ";
            n->print(ss);

            toks.push_back( Token(InterpolatedFragment(InterpolatedFragment::EXPR, n.release())) );

            toks.push_back( Token(TOK_BRACE_OPEN) );
            // Auto-generated message
            toks.push_back( Token(TOK_IDENT, "panic") );
            toks.push_back( Token(TOK_EXCLAM) );
            toks.push_back( Token(TOK_PAREN_OPEN) );
            toks.push_back( Token(TOK_STRING, ss.str()) );
            toks.push_back( Token(TOK_PAREN_CLOSE) );
        }
        else
        {
            throw ParseError::Unexpected(lex, tok, {TOK_COMMA, TOK_EOF});
        }

        toks.push_back( Token(TOK_BRACE_CLOSE) );

        return box$( TTStreamO(sp, TokenTree(Ident::Hygiene::new_scope(), mv$(toks))) );
    }
};

void Expand_init_assert()
{
    if( TARGETVER_1_29 )
    {
        Register_Synext_Macro("assert", ::std::unique_ptr<ExpandProcMacro>(new CExpander_assert));
    }
}