// p≡p Message API

// Copyleft (c) 2019, p≡p foundation
// this file is under GNU General Public License 3.0
// see LICENSE.txt

// written by Volker Birk


enum text_format {
    hex text_format_plain 0;
    hex text_format_html 1;
    hex text_format_other 0xff;
}


enum msg_direction {
    item dir_incoming 0;
    item dir_outgoing 1;
}


enum enc_format {
    item enc_none 0 doc='message is not encrypted';
    item enc_pieces 1 doc='inline PGP + PGP extensions';
    item enc_S_MIME 2 doc='RFC5751';
    item enc_PGP_MIME 3 doc='RFC3156';
    item enc_PEP 4 doc='pEp encryption format';
    item enc_PGP_MIME_Outlook1 5 doc='Message B0rken by Outlook type 1';
}


enum ratings {
    item rating_undefined 0;
    item rating_cannot_decrypt 1;
    item rating_have_no_key 2;
    item rating_unencrypted 3;
    item rating_unencrypted_for_some doc="don't use this any more",
    item rating_unreliable 4;
    item rating_reliable 5;
    item rating_trusted 6;
    item rating_trusted_and_anonymized 7;
    item rating_fully_anonymous 8;
    item rating_mistrust -1;
    item rating_b0rken -2;
    item rating_under_attack -3;
}
    

enum colors {
        item color_no_color 0;
        item color_yellow 1;
        item color_green 2;
        item color_red -1;
}


struct message {
    field msg_direction dir;
    field string id doc='string of message ID';
    field string shortmsg doc='string of short message';
    field string longmsg doc='string of long message (plain)';
    field string longmsg_formatted doc='string of long message (formatted)';
    field blob_list attachments doc='blobs with attachements';
    field blob_ref rawmsg_ref doc='reference to raw message data';
    field size_t rawmsg_size doc='size of raw message data';
    field timestamp sent doc='when the message is sent';
    field timestamp recv doc='when the message is received';
    field identity from doc='whom the message is from';
    field identity_list to doc='whom the message is to';
    field identity recv_by doc='via which identity the message is received';
    field identity_list cc doc='whom a CC is being sent';
    field identity_list bcc doc='whom a BCC is being sent';
    field identity_list reply_to doc='where a reply should go to';
    field string_list in_reply_to doc='list of strings with MessageIDs of refering messages';
    field message_ref refering_msg_ref doc='reference to refering message';
    field string_list references doc='list of strings with references';
    field message_ref_list refered_by doc='list of references to messages being refered';
    field string_list keywords doc='list of strings with keywords';
    field string comments doc='string with comments';
    field stringpair_list opt_fields doc='optional fields';
    field enc_format format doc='format of encrypted data';

    new (msg_direction dir);
}


protocol session {
    method encrypt_message
        doc="encrypt message in memory"
    {
        // parms

        supply message src
        doc="""
            message to encrypt - usually in-only, but can be in-out for
            unencrypted messages; in that case, we may attach the key and
            decorate the message
            """;

        use hash_list extra doc="extra keys for encryption";

        create message dst
        doc="""
            pointer to new encrypted message or #NV if no encryption could
            take place
            """;

        use enc_format format doc="encrypted format";

        // flags

        flags {
            flag default 0x0 doc='"default" means whatever the default behaviour for the function is.';
            flag force_encryption 0x1;
            flag force_unsigned 0x2 doc='This flag is for special use cases and should not be used by normal pEp clients!';
            flag force_no_attached_key 0x4;
            flag inner_message 0x8 doc='This is mainly used by pEp clients to send private keys to their own PGP-only device.';
            flag force_version_1 0x10 doc='This is mainly used by pEp clients to send private keys to their own PGP-only device';
            flag key_reset_only 0x20;
        }

        // exceptions

        throws key_has_ambig_name doc="at least one of the receipient keys has an ambiguous name";

        throws unencrypted
        doc="""
            on demand or no recipients with usable key, is left unencrypted,
            and key is attached to it 
            """;
    }


    method encrypt_message_and_add_priv_key
        doc="encrypt message in memory, adding an encrypted private key (encrypted separately and sent within the inner message)"
    {
        // parms

        use message src doc="message to encrypt";

        create message dst
            doc="pointer to new encrypted message or empty if no encryption could take place";

        use hash to_fpr
            doc="fingerprint of the recipient key to which the private key should be encrypted";

        use enc_format format doc="encrypted format";

        // flags

        flags {
            flag default 0x0 doc='"default" means whatever the default behaviour for the function is.';
            flag force_encryption 0x1;
            flag force_unsigned 0x2 doc='This flag is for special use cases and should not be used by normal pEp clients!';
            flag force_no_attached_key 0x4;
            flag inner_message 0x8 doc='This is mainly used by pEp clients to send private keys to their own PGP-only device.';
            flag force_version_1 0x10 doc='This is mainly used by pEp clients to send private keys to their own PGP-only device';
            flag key_reset_only 0x20;
        }

        // exceptions

        throws key_has_ambig_name doc="at least one of the receipient keys has an ambiguous name";

        throws unencrypted
            doc="""
                on demand or no recipients with usable key, is left unencrypted, 
                and key is attached to it
                """;
    }


    method encrypt_message_for_self
        doc="""
            encrypt message in memory for user's identity only,
            ignoring recipients and other identities from the message
            """
    {
        // parms

        use identity target_id
        doc="""
            self identity this message should be encrypted for. Message is NOT encrypted for 
            identities other than the target_id (and then, only if the target_id refers to self!).
            """;

        use message src doc="message to encrypt";

        use hash_list extra doc="extra keys for encryption";

        create message dst doc="pointer to new encrypted message or empty on failure";

        use enc_format format doc="encrypted format";

        // flags

        flags {
            flag default 0x0 doc='"default" means whatever the default behaviour for the function is.';
            flag force_encryption 0x1;
            flag force_unsigned 0x2 doc='This flag is for special use cases and should not be used by normal pEp clients!';
            flag force_no_attached_key 0x4;
            flag inner_message 0x8 doc='This is mainly used by pEp clients to send private keys to their own PGP-only device.';
            flag force_version_1 0x10 doc='This is mainly used by pEp clients to send private keys to their own PGP-only device';
            flag key_reset_only 0x20;
        }

        doc | (FIXME: The exceptions may not be correct or complete)

        throws key_not_found doc="at least one of the receipient keys could not be found";

        throws key_has_ambig_name doc="at least one of the receipient keys has an ambiguous name";

        throws get_key_failed doc="cannot retrieve key";
    }


    method decrypt_message
        doc="decrypt message in memory"
    {
        // parms

        supply message src
        doc="""
            message to decrypt. 
            The ownership of src remains with the caller - however, the contents 
            might be modified (strings freed and allocated anew or set to empty,
            etc) intentionally; when this happens, decrypt_flag_src_modified is set.
            """;

        create message dst doc="pointer to new decrypted message or empty on failure";

        supply hash_list keylist
        doc="""
            in: stringlist with additional keyids for reencryption if needed
                (will be freed and replaced with output keylist)
            out: stringlist with keyids used for signing and encryption. first
                first key is signer, additional keys are the ones it was encrypted
                to. Only signer and whichever of the user's keys was used are reliable.
            The ownership of keylist goes to the caller.
            If src is unencrypted this function returns unencrypted and sets dst to empty.
            """;

        return rating msg_rating doc="rating for the message";

        // flags
        
        flags {
            flag decrypt_flag_own_private_key 0x1 
            doc="""
                private key was imported for one of our addresses (NOT trusted
                or set to be used - handshake/trust is required for that)
                """;
            flag decrypt_flag_consume 0x2 doc='used by sync';
            flag decrypt_flag_ignore 0x4 doc='used by sync';
            flag decrypt_flag_src_modified 0x8 
            doc="""
                indicates that the src object has been modified. At the moment,
                this is always as a direct result of the behaviour driven
                by the input flags. This flag is the ONLY value that should be
                relied upon to see if such changes have taken place.
                """;
            flag decrypt_flag_untrusted_server 0x100 
            doc="""
                input flags. Used to signal that decrypt function should engage in behaviour
                specified for when the server storing the source is untrusted.
                """;
        }

    // exceptions
    
    throws decrypted doc="if message decrypted but not verified";

    throws cannot_reencrypt
        doc="""
            if message was decrypted (and possibly verified) but a reencryption 
            operation is expected by the caller and failed.
            """;

    throws unencrypted
        doc="""
            if src is unencrypted this function returns unencrypted and sets
            dst to empty.
            """;

    throws any doc="all error status values allowed";
    }


    method own_message_private_key_details
        doc="""
            details on own key in own message. Note: In order to obtain details about key 
            to be possibly imported as a replacement of key currently used as own identity, 
            application passes message that have been previously flagged by decrypt_message() 
            as own message containing own key to this function.
            """
    {
    //parms

    use message msg
    doc="""
        message to decrypt. msg MUST be encrypted so that this function 
        can check own signature.
        """;

    create identity ident doc="identity containing uid, address and fpr of key";

    // exceptions

    throws any doc="error status"
    }


    method outgoing_message_rating
        doc="get rating for an outgoing message"
    {
    //parms

    use message msg
    doc="""
        message to get the rating for. From must point to a valid pEp_identity.
        Dir must be dir_outgoing.
        """;

    return rating msg_rating doc="rating for the message";

    // exceptions

    throws any doc="error status"
    }


    method outgoing_message_rating_preview
        doc="get rating preview"
    {
    //parms

    use message msg
    doc="""
        message to get the rating for. From must point to a valid pEp_identity.
        Dir must be dir_outgoing.
        """;

    return rating msg_rating doc="rating preview for the message";

    // exceptions

    throws any doc="error status"
    }


    method identity_rating
        doc="get rating for a single identity"
    {
    //parms

    use identity ident doc="identity to get the rating for";

    return rating identity_rating doc="rating for the identity";

    // exceptions

    throws any doc="error status"
    }


    method get_trustwords
        doc="get full trustwords string for a *pair* of identities"
    {
    //parms

    use identity id1 doc="identity of first party in communication - fpr can't be empty";

    use identity id2 doc="identity of second party in communication - fpr can't be empty";

    use ISO639_1 lang doc="string with ISO 639-1 language code";

    create string words
        doc="""
            string with all trustwords, separated 
            by a blank each. Empty if language is not supported or trustword 
            wordlist is damaged or unavailable. 
            The word pointer goes to the ownership of the caller. 
            The caller is responsible to free() it (on Windoze use pEp_free())
            """;

    use bool full
        doc="""
            if true, generate ALL trustwords for these identities.
            else, generate a fixed-size subset. (TODO: fixed-minimum-entropy
            subset in next version)
            """;

    // exceptions

    throws out_of_memory
        doc="out of memory";

    throws trustword_not_found
        doc="at least one trustword not found";
    }


    method get_message_trustwords
        doc="get full trustwords string for message sender and reciever identities"
    {
    //parms

    use message msg doc="message to get sender identity from";

    use hash_list keylist
        doc="empty if message to be decrypted, keylist returned by decrypt_message() otherwise.";

    use identity received_by doc="identity for account receiving message can't be empty";

    use ISO639_1 lang doc="C string with ISO 639-1 language code";

    create string words
        doc="""
            string with all trustwords, separated by a blank each.
            Empty if language is not supported or trustword  wordlist is damaged or unavailable.
            """;

    use bool full
        doc="""
            if true, generate ALL trustwords for these identities.
            else, generate a fixed-size subset. (TODO: fixed-minimum-entropy
            subset in next version)
            """;

    // exceptions

    throws out_of_memory doc="out of memory";

    throws trustword_not_found doc="at least one trustword not found";

    throws like decrypt_message doc="error status of decrypt_message() if decryption fails"
    }


    method re_evaluate_message_rating
        doc="re-evaluate already decrypted message rating"
    {
    //parms

    use message msg
        doc="message to get the rating for. msg->from must point to a valid pEp_identity";

    use hash_list x_keylist doc="decrypted message recipients keys fpr";

    use rating x_enc_status doc="original rating for the decrypted message";

    return rating msg_rating doc="rating for the message";

    // exceptions

    throws illegal_value
        doc="""
            if decrypted message doesn't contain X-EncStatus optional field and 
            x_enc_status is pEp_rating_udefined or if decrypted message doesn't 
            contain X-Keylist optional field and x_keylist is empty.
            """;

    throws out_of_memory doc="if not enough memory could be allocated";
    }


    method get_key_rating_for_user
        doc="get the rating of a certain key for a certain user"
    {
    //parms

    use string user_id doc="string with user ID";

    use string fpr doc="string with fingerprint";

    return rating key_rating doc="rating of key for this user";
        
    // exceptions

    throws record_not_found
        doc="if no trust record for user_id and fpr can be found"
    }
}


func color_from_rating
    doc="calculate color from rating"
{
    // parms

    use color_from_rating rating doc="color representing that rating"

    // return value
    return color rating_color doc="color representing that rating"
}


func get_binary_path
    doc="retrieve path of cryptotech binary if available"
{
    //parms

    use cryptotech tech
    doc="cryptotech to get the binary for";

    use string path
    doc="""
        path to cryptotech binary or empty if not available. **path is owned by 
        the library, do not change it!;
        """
}