/* notmuch - Not much of an email program, (just index and search)
 *
 * Copyright © 2012 Jameson Rollins
 *
 * 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 https://www.gnu.org/licenses/ .
 *
 * Authors: Jameson Rollins <jrollins@finestructure.net>
 *          Daniel Kahn Gillmor <dkg@fifthhorseman.net>
 */

#include "notmuch.h"
#include "crypto.h"
#include <string.h>

#define ARRAY_SIZE(arr) (sizeof (arr) / sizeof (arr[0]))

/* Create a GPG context (GMime 2.6) */
static GMimeCryptoContext*
create_gpg_context (_notmuch_crypto_t *crypto)
{
    GMimeCryptoContext *gpgctx;

    if (crypto->gpgctx) {
	return crypto->gpgctx;
    }

    /* TODO: GMimePasswordRequestFunc */
    gpgctx = g_mime_gpg_context_new (NULL, crypto->gpgpath ? crypto->gpgpath : "gpg");
    if (! gpgctx) {
	fprintf (stderr, "Failed to construct gpg context.\n");
	return NULL;
    }
    crypto->gpgctx = gpgctx;

    g_mime_gpg_context_set_use_agent ((GMimeGpgContext *) gpgctx, TRUE);
    g_mime_gpg_context_set_always_trust ((GMimeGpgContext *) gpgctx, FALSE);

    return crypto->gpgctx;
}

/* Create a PKCS7 context (GMime 2.6) */
static notmuch_crypto_context_t *
create_pkcs7_context (notmuch_crypto_t *crypto)
{
    notmuch_crypto_context_t *pkcs7ctx;

    if (crypto->pkcs7ctx)
	return crypto->pkcs7ctx;

    /* TODO: GMimePasswordRequestFunc */
    pkcs7ctx = g_mime_pkcs7_context_new (NULL);
    if (! pkcs7ctx) {
	fprintf (stderr, "Failed to construct pkcs7 context.\n");
	return NULL;
    }
    crypto->pkcs7ctx = pkcs7ctx;

    g_mime_pkcs7_context_set_always_trust ((GMimePkcs7Context *) pkcs7ctx,
					   FALSE);

    return crypto->pkcs7ctx;
}
static const struct {
    const char *protocol;
    GMimeCryptoContext *(*get_context) (_notmuch_crypto_t *crypto);
} protocols[] = {
    {
	.protocol = "application/pgp-signature",
	.get_context = create_gpg_context,
    },
    {
	.protocol = "application/pgp-encrypted",
	.get_context = create_gpg_context,
    },
    {
	.protocol = "application/pkcs7-signature",
	.get_context = create_pkcs7_context,
    },
    {
	.protocol = "application/x-pkcs7-signature",
	.get_context = create_pkcs7_context,
    },
};

/* for the specified protocol return the context pointer (initializing
 * if needed) */
GMimeCryptoContext *
_notmuch_crypto_get_gmime_context (_notmuch_crypto_t *crypto, const char *protocol)
{
    GMimeCryptoContext *cryptoctx = NULL;
    size_t i;

    if (! protocol) {
	fprintf (stderr, "Cryptographic protocol is empty.\n");
	return cryptoctx;
    }

    /* As per RFC 1847 section 2.1: "the [protocol] value token is
     * comprised of the type and sub-type tokens of the Content-Type".
     * As per RFC 1521 section 2: "Content-Type values, subtypes, and
     * parameter names as defined in this document are
     * case-insensitive."  Thus, we use strcasecmp for the protocol.
     */
    for (i = 0; i < ARRAY_SIZE (protocols); i++) {
	if (strcasecmp (protocol, protocols[i].protocol) == 0)
	    return protocols[i].get_context (crypto);
    }

    fprintf (stderr, "Unknown or unsupported cryptographic protocol %s.\n",
	     protocol);

    return NULL;
}

void
_notmuch_crypto_cleanup (_notmuch_crypto_t *crypto)
{
    if (crypto->gpgctx) {
	g_object_unref (crypto->gpgctx);
	crypto->gpgctx = NULL;
    }

    if (crypto->pkcs7ctx) {
	g_object_unref (crypto->pkcs7ctx);
	crypto->pkcs7ctx = NULL;
    }
}