/*
 * Copyright (C) 2011 John Szakmeister <john@szakmeister.net>
 *               2012 Philipp A. Hartmann <pah@qo.cx>
 *
 *  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 <stdarg.h>
#include <stdlib.h>
#include <errno.h>
#include <gnome-keyring.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 }

void credential_init(struct credential *c);
void credential_clear(struct credential *c);
int  credential_read(struct credential *c);
void credential_write(const struct credential *c);

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

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

#define CREDENTIAL_OP_END \
  { NULL,NULL }

/*
 * Table with operation callbacks is defined in concrete
 * credential helper implementation and contains entries
 * like { "get", function_to_get_credential } terminated
 * by CREDENTIAL_OP_END.
 */
struct credential_operation const credential_helper_ops[];

/* ---------------- common helper functions ----------------- */

static inline void free_password(char *password)
{
        char *c = password;
        if (!password)
                return;

        while (*c) *c++ = '\0';
        free(password);
}

static inline void warning(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        fprintf(stderr, "warning: ");
        vfprintf(stderr, fmt, ap);
        fprintf(stderr, "\n" );
        va_end(ap);
}

static inline void error(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        fprintf(stderr, "error: ");
        vfprintf(stderr, fmt, ap);
        fprintf(stderr, "\n" );
        va_end(ap);
}

static inline void die(const char *fmt, ...)
{
        va_list ap;

        va_start(ap,fmt);
        error(fmt, ap);
        va_end(ap);
        exit(EXIT_FAILURE);
}

static inline void die_errno(int err)
{
        error("%s", strerror(err));
        exit(EXIT_FAILURE);
}

static inline char *xstrdup(const char *str)
{
        char *ret = strdup(str);
        if (!ret)
                die_errno(errno);

        return ret;
}

/* ----------------- GNOME Keyring functions ----------------- */

/* create a special keyring option string, if path is given */
static char* keyring_object(struct credential *c)
{
        char* object = NULL;

        if (!c->path)
                return object;

        object = (char*) malloc(strlen(c->host)+strlen(c->path)+8);
        if(!object)
                die_errno(errno);

        if(c->port)
                sprintf(object,"%s:%hd/%s",c->host,c->port,c->path);
        else
                sprintf(object,"%s/%s",c->host,c->path);

        return object;
}

int keyring_get(struct credential *c)
{
        char* object = NULL;
        GList *entries;
        GnomeKeyringNetworkPasswordData *password_data;
        GnomeKeyringResult result;

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

        object = keyring_object(c);

        result = gnome_keyring_find_network_password_sync(
                                c->username,
                                NULL /* domain */,
                                c->host,
                                object,
                                c->protocol,
                                NULL /* authtype */,
                                c->port,
                                &entries);

        free(object);

        if (result == GNOME_KEYRING_RESULT_NO_MATCH)
                return EXIT_SUCCESS;

        if (result == GNOME_KEYRING_RESULT_CANCELLED)
                return EXIT_SUCCESS;

        if (result != GNOME_KEYRING_RESULT_OK) {
                error("%s",gnome_keyring_result_to_message(result));
                return EXIT_FAILURE;
        }

        /* pick the first one from the list */
        password_data = (GnomeKeyringNetworkPasswordData *) entries->data;

        free_password(c->password);
        c->password = xstrdup(password_data->password);

        if (!c->username)
                c->username = xstrdup(password_data->user);

        gnome_keyring_network_password_list_free(entries);

        return EXIT_SUCCESS;
}


int keyring_store(struct credential *c)
{
        guint32 item_id;
        char  *object = 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;

        object = keyring_object(c);

        gnome_keyring_set_network_password_sync(
                                GNOME_KEYRING_DEFAULT,
                                c->username,
                                NULL /* domain */,
                                c->host,
                                object,
                                c->protocol,
                                NULL /* authtype */,
                                c->port,
                                c->password,
                                &item_id);

        free(object);
        return EXIT_SUCCESS;
}

int keyring_erase(struct credential *c)
{
        char  *object = NULL;
        GList *entries;
        GnomeKeyringNetworkPasswordData *password_data;
        GnomeKeyringResult result;

        /*
         * 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;

        object = keyring_object(c);

        result = gnome_keyring_find_network_password_sync(
                                c->username,
                                NULL /* domain */,
                                c->host,
                                object,
                                c->protocol,
                                NULL /* authtype */,
                                c->port,
                                &entries);

        free(object);

        if (result == GNOME_KEYRING_RESULT_NO_MATCH)
                return EXIT_SUCCESS;

        if (result == GNOME_KEYRING_RESULT_CANCELLED)
                return EXIT_SUCCESS;

        if (result != GNOME_KEYRING_RESULT_OK)
        {
                error("%s",gnome_keyring_result_to_message(result));
                return EXIT_FAILURE;
        }

        /* pick the first one from the list (delete all matches?) */
        password_data = (GnomeKeyringNetworkPasswordData *) entries->data;

        result = gnome_keyring_item_delete_sync(
                password_data->keyring, password_data->item_id);

        gnome_keyring_network_password_list_free(entries);

        if (result != GNOME_KEYRING_RESULT_OK)
        {
                error("%s",gnome_keyring_result_to_message(result));
                return EXIT_FAILURE;
        }

        return EXIT_SUCCESS;
}

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

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

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

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

        credential_init(c);
}

int credential_read(struct credential *c)
{
        char    buf[1024];
        ssize_t line_len = 0;
        char   *key      = buf;
        char   *value;

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

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

                if(!line_len)
                        break;

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

                if (!strcmp(key, "protocol")) {
                        free(c->protocol);
                        c->protocol = xstrdup(value);
                } else if (!strcmp(key, "host")) {
                        free(c->host);
                        c->host = xstrdup(value);
                        value = strrchr(c->host,':');
                        if (value) {
                                *value++ = '\0';
                                c->port = atoi(value);
                        }
                } else if (!strcmp(key, "path")) {
                        free(c->path);
                        c->path = xstrdup(value);
                } else if (!strcmp(key, "username")) {
                        free(c->username);
                        c->username = xstrdup(value);
                } else if (!strcmp(key, "password")) {
                        free_password(c->password);
                        c->password = xstrdup(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.
                 */
        }
        return 0;
}

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

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]);
                goto out;
        }

        /* 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;
}