// -*- mode: Rust; -*-

use crate::message::lexer;

grammar;

pub Message: () = {
    LITERAL,
    CompressedData,
    EncryptedPart,
    SignedPart,
    OPAQUE_CONTENT,
};

CompressedData: () = {
    COMPRESSED_DATA Message POP
};

SeipPart: () = {
    SEIP Message MDC POP,
    SEIP OPAQUE_CONTENT POP,
}

AedPart: () = {
    AED Message POP,
}

// An encrypted part is 0 or more ESKs followed by an encryption container.
EncryptedPart: () = {
    EncryptionContainer,
    ESKS EncryptionContainer,
};

EncryptionContainer: () = {
    SeipPart,
    AedPart,
};

ESKS: () = {
    ESK,
    ESKS ESK,
};

ESK: () = {
    PKESK,
    SKESK,
};

// Signatures bracket a message like so:
//
//   OPS OPS Message SIG SIG
//
// or, there are 1 or more signatures preceding a Message (this is an
// artifact of old PGP versions):
//
//   SIG SIG Message
SignedPart: () = {
    SIG Message,
    OPS Message SIG,
}

extern {
    type Location = usize;
    type Error = lexer::LexicalError;

    enum lexer::Token {
        LITERAL => lexer::Token::Literal,
        COMPRESSED_DATA => lexer::Token::CompressedData,
        SKESK => lexer::Token::SKESK,
        PKESK => lexer::Token::PKESK,
        SEIP => lexer::Token::SEIP,
        MDC => lexer::Token::MDC,
        AED => lexer::Token::AED,
        OPS => lexer::Token::OPS,
        SIG => lexer::Token::SIG,
        POP => lexer::Token::Pop,
        OPAQUE_CONTENT => lexer::Token::OpaqueContent,
    }
}