/*
 * Copyright (C) 2011 John Szakmeister <john@szakmeister.net>
 *               2012 Philipp A. Hartmann <pah@qo.cx>
 *               2016 Mantas Mikulėnas <grawity@gmail.com>
 *
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * Credits:
 * - GNOME Keyring API handling originally written by John Szakmeister
 * - ported to credential helper API by Philipp A. Hartmann
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <glib.h>
#include <libsecret/secret.h>

/*
 * This credential struct and API is simplified from git's credential.{h,c}
 */
struct credential {
        char *protocol;
        char *host;
        unsigned short port;
        char *path;
        char *username;
        char *password;
};

#define CREDENTIAL_INIT { NULL, NULL, 0, NULL, NULL, NULL }

typedef int (*credential_op_cb)(struct credential *);

struct credential_operation {
        char *name;
        credential_op_cb op;
};

#define CREDENTIAL_OP_END { NULL, NULL }

/* ----------------- Secret Service functions ----------------- */

static char *make_label(struct credential *c)
{
        if (c->port)
                return g_strdup_printf("Git: %s://%s:%hu/%s",
                                        c->protocol, c->host, c->port, c->path ? c->path : "");
        else
                return g_strdup_printf("Git: %s://%s/%s",
                                        c->protocol, c->host, c->path ? c->path : "");
}

static GHashTable *make_attr_list(struct credential *c)
{
        GHashTable *al = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, g_free);

        if (c->username)
                g_hash_table_insert(al, "user", g_strdup(c->username));
        if (c->protocol)
                g_hash_table_insert(al, "protocol", g_strdup(c->protocol));
        if (c->host)
                g_hash_table_insert(al, "server", g_strdup(c->host));
        if (c->port)
                g_hash_table_insert(al, "port", g_strdup_printf("%hu", c->port));
        if (c->path)
                g_hash_table_insert(al, "object", g_strdup(c->path));

        return al;
}

static int keyring_get(struct credential *c)
{
        SecretService *service = NULL;
        GHashTable *attributes = NULL;
        GError *error = NULL;
        GList *items = NULL;

        if (!c->protocol || !(c->host || c->path))
                return EXIT_FAILURE;

        service = secret_service_get_sync(0, NULL, &error);
        if (error != NULL) {
                g_critical("could not connect to Secret Service: %s", error->message);
                g_error_free(error);
                return EXIT_FAILURE;
        }

        attributes = make_attr_list(c);
        items = secret_service_search_sync(service,
                                           SECRET_SCHEMA_COMPAT_NETWORK,
                                           attributes,
                                           SECRET_SEARCH_LOAD_SECRETS | SECRET_SEARCH_UNLOCK,
                                           NULL,
                                           &error);
        g_hash_table_unref(attributes);
        if (error != NULL) {
                g_critical("lookup failed: %s", error->message);
                g_error_free(error);
                return EXIT_FAILURE;
        }

        if (items != NULL) {
                SecretItem *item;
                SecretValue *secret;
                const char *s;

                item = items->data;
                secret = secret_item_get_secret(item);
                attributes = secret_item_get_attributes(item);

                s = g_hash_table_lookup(attributes, "user");
                if (s) {
                        g_free(c->username);
                        c->username = g_strdup(s);
                }

                s = secret_value_get_text(secret);
                if (s) {
                        g_free(c->password);
                        c->password = g_strdup(s);
                }

                g_hash_table_unref(attributes);
                secret_value_unref(secret);
                g_list_free_full(items, g_object_unref);
        }

        return EXIT_SUCCESS;
}


static int keyring_store(struct credential *c)
{
        char *label = NULL;
        GHashTable *attributes = NULL;
        GError *error = NULL;

        /*
         * Sanity check that what we are storing is actually sensible.
         * In particular, we can't make a URL without a protocol field.
         * Without either a host or pathname (depending on the scheme),
         * we have no primary key. And without a username and password,
         * we are not actually storing a credential.
         */
        if (!c->protocol || !(c->host || c->path) ||
            !c->username || !c->password)
                return EXIT_FAILURE;

        label = make_label(c);
        attributes = make_attr_list(c);
        secret_password_storev_sync(SECRET_SCHEMA_COMPAT_NETWORK,
                                    attributes,
                                    NULL,
                                    label,
                                    c->password,
                                    NULL,
                                    &error);
        g_free(label);
        g_hash_table_unref(attributes);

        if (error != NULL) {
                g_critical("store failed: %s", error->message);
                g_error_free(error);
                return EXIT_FAILURE;
        }

        return EXIT_SUCCESS;
}

static int keyring_erase(struct credential *c)
{
        GHashTable *attributes = NULL;
        GError *error = NULL;

        /*
         * Sanity check that we actually have something to match
         * against. The input we get is a restrictive pattern,
         * so technically a blank credential means "erase everything".
         * But it is too easy to accidentally send this, since it is equivalent
         * to empty input. So explicitly disallow it, and require that the
         * pattern have some actual content to match.
         */
        if (!c->protocol && !c->host && !c->path && !c->username)
                return EXIT_FAILURE;

        attributes = make_attr_list(c);
        secret_password_clearv_sync(SECRET_SCHEMA_COMPAT_NETWORK,
                                    attributes,
                                    NULL,
                                    &error);
        g_hash_table_unref(attributes);

        if (error != NULL) {
                g_critical("erase failed: %s", error->message);
                g_error_free(error);
                return EXIT_FAILURE;
        }

        return EXIT_SUCCESS;
}

/*
 * Table with helper operation callbacks, used by generic
 * credential helper main function.
 */
static struct credential_operation const credential_helper_ops[] = {
        { "get",   keyring_get },
        { "store", keyring_store },
        { "erase", keyring_erase },
        CREDENTIAL_OP_END
};

/* ------------------ credential functions ------------------ */

static void credential_init(struct credential *c)
{
        memset(c, 0, sizeof(*c));
}

static void credential_clear(struct credential *c)
{
        g_free(c->protocol);
        g_free(c->host);
        g_free(c->path);
        g_free(c->username);
        g_free(c->password);

        credential_init(c);
}

static int credential_read(struct credential *c)
{
        char *buf;
        size_t line_len;
        char *key;
        char *value;

        key = buf = g_malloc(1024);

        while (fgets(buf, 1024, stdin)) {
                line_len = strlen(buf);

                if (line_len && buf[line_len-1] == '\n')
                        buf[--line_len] = '\0';

                if (!line_len)
                        break;

                value = strchr(buf, '=');
                if (!value) {
                        g_warning("invalid credential line: %s", key);
                        g_free(buf);
                        return -1;
                }
                *value++ = '\0';

                if (!strcmp(key, "protocol")) {
                        g_free(c->protocol);
                        c->protocol = g_strdup(value);
                } else if (!strcmp(key, "host")) {
                        g_free(c->host);
                        c->host = g_strdup(value);
                        value = strrchr(c->host, ':');
                        if (value) {
                                *value++ = '\0';
                                c->port = atoi(value);
                        }
                } else if (!strcmp(key, "path")) {
                        g_free(c->path);
                        c->path = g_strdup(value);
                } else if (!strcmp(key, "username")) {
                        g_free(c->username);
                        c->username = g_strdup(value);
                } else if (!strcmp(key, "password")) {
                        g_free(c->password);
                        c->password = g_strdup(value);
                        while (*value)
                                *value++ = '\0';
                }
                /*
                 * Ignore other lines; we don't know what they mean, but
                 * this future-proofs us when later versions of git do
                 * learn new lines, and the helpers are updated to match.
                 */
        }

        g_free(buf);

        return 0;
}

static void credential_write_item(FILE *fp, const char *key, const char *value)
{
        if (!value)
                return;
        fprintf(fp, "%s=%s\n", key, value);
}

static void credential_write(const struct credential *c)
{
        /* only write username/password, if set */
        credential_write_item(stdout, "username", c->username);
        credential_write_item(stdout, "password", c->password);
}

static void usage(const char *name)
{
        struct credential_operation const *try_op = credential_helper_ops;
        const char *basename = strrchr(name, '/');

        basename = (basename) ? basename + 1 : name;
        fprintf(stderr, "usage: %s <", basename);
        while (try_op->name) {
                fprintf(stderr, "%s", (try_op++)->name);
                if (try_op->name)
                        fprintf(stderr, "%s", "|");
        }
        fprintf(stderr, "%s", ">\n");
}

int main(int argc, char *argv[])
{
        int ret = EXIT_SUCCESS;

        struct credential_operation const *try_op = credential_helper_ops;
        struct credential cred = CREDENTIAL_INIT;

        if (!argv[1]) {
                usage(argv[0]);
                exit(EXIT_FAILURE);
        }

        g_set_application_name("Git Credential Helper");

        /* lookup operation callback */
        while (try_op->name && strcmp(argv[1], try_op->name))
                try_op++;

        /* unsupported operation given -- ignore silently */
        if (!try_op->name || !try_op->op)
                goto out;

        ret = credential_read(&cred);
        if (ret)
                goto out;

        /* perform credential operation */
        ret = (*try_op->op)(&cred);

        credential_write(&cred);

out:
        credential_clear(&cred);
        return ret;
}