/*

    Copyright (C) 2011  ABRT team

    Copyright (C) 2011  RedHat Inc

    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.,

    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

*/

#include "libabrt.h"

/* We remember N worst files and their sizes, not just one:

 * if DIR is deep, scanning it takes *a few seconds* even if it's in cache.

 * If we rescan it after each single file deletion, it can be VERY slow.

 * (I observed ~20 min long case).

 */

#define MAX_VICTIM_LIST_SIZE 128

struct name_and_size {

    off_t size;

    double weighted_size_and_age;

    char name[1];

};

/* Updates a list of files sorted by increasing weighted_size_and_age.

 */

static GList *insert_name_and_sizes(GList *list, const char *name, double wsa, off_t sz)

{

    struct name_and_size *ns;

    unsigned list_len = 0;

    GList *cur = list;

    while (cur)

    {

        ns = cur->data;

        if (ns->weighted_size_and_age >= wsa)

            break;

        list_len++;

        cur = cur->next;

    }

    list_len += g_list_length(cur);

    if (cur != list || list_len < MAX_VICTIM_LIST_SIZE)

    {

        ns = xmalloc(sizeof(*ns) + strlen(name));

        ns->weighted_size_and_age = wsa;

        ns->size = sz;

        strcpy(ns->name, name);

        list = g_list_insert_before(list, cur, ns);

        list_len++;

        if (list_len > MAX_VICTIM_LIST_SIZE)

        {

            free(list->data);

            list = g_list_delete_link(list, list);

        }

    }

    return list;

}

static double get_dir_size(const char *dirname,

                GList **pp_worst_file_list,

                GList *preserve_files_list

) {

    DIR *dp = opendir(dirname);

    if (!dp)

        return 0;

    /* "now" is used only if caller wants to know worst_file */

    time_t now = pp_worst_file_list ? time(NULL) : 0;

    struct dirent *dent;

    double size = 0;

    while ((dent = readdir(dp)) != NULL)

    {

        if (dot_or_dotdot(dent->d_name))

            continue;

        char *fullname = concat_path_file(dirname, dent->d_name);

        struct stat stats;

        if (lstat(fullname, &stats) != 0)

            goto next;

        if (S_ISDIR(stats.st_mode))

        {

            double sz = get_dir_size(fullname, pp_worst_file_list, preserve_files_list);

            size += sz;

        }

        else if (S_ISREG(stats.st_mode) || S_ISLNK(stats.st_mode))

        {

            double sz = stats.st_size;

            /* Account for filename and inode storage (approximately).

             * This also makes even zero-length files to have nonzero cost.

             */

            sz += strlen(dent->d_name) + sizeof(stats);

            size += sz;

            if (pp_worst_file_list)

            {

                GList *cur = preserve_files_list;

                while (cur)

                {

                    //log_warning("'%s' ? '%s'", fullname, *pp);

                    if (strcmp(fullname, (char*)cur->data) == 0)

                        goto next;

                    cur = cur->next;

                }

                /* Calculate "weighted" size and age

                 * w = sz_kbytes * age_mins */

                sz /= 1024;

                long age = (now - stats.st_mtime) / 60;

                if (age > 1)

                    sz *= age;

                *pp_worst_file_list = insert_name_and_sizes(*pp_worst_file_list, fullname, sz, stats.st_size);

            }

        }

 next:

        free(fullname);

    }

    closedir(dp);

    return size;

}

static const char *parse_size_pfx(double *size, const char *str)

{

    errno = (isdigit(str[0]) ? 0 : ERANGE);

    char *end;

    *size = strtoull(str, &end, 10);

    if (end != str)

    {

        char c = (*end | 0x20); /* lowercasing */

        if (c == 'k')

            end++, *size *= 1024;

        else if (c == 'm')

            end++, *size *= 1024*1024;

        else if (c == 'g')

            end++, *size *= 1024*1024*1024;

        else if (c == 't')

            end++, *size *= 1024.0*1024*1024*1024;

    }

    if (errno || end == str || *end != ':')

        perror_msg_and_die("Bad size prefix in '%s'", str);

    return end + 1;

}

static void delete_dirs(gpointer data, gpointer exclude_path)

{

    double cap_size;

    const char *dir = parse_size_pfx(&cap_size, data);

    trim_problem_dirs(dir, cap_size, exclude_path);

}

static void delete_files(gpointer data, gpointer void_preserve_list)

{

    double cap_size;

    const char *dir = parse_size_pfx(&cap_size, data);

    GList *preserve_files_list = void_preserve_list;

    unsigned count = 100;

    while (--count != 0)

    {

        GList *worst_file_list = NULL;

        double cur_size = get_dir_size(dir, &worst_file_list, preserve_files_list);

        if (cur_size <= cap_size || !worst_file_list)

        {

            list_free_with_free(worst_file_list);

            log_info("cur_size:%.0f cap_size:%.0f, no (more) trimming", cur_size, cap_size);

            break;

        }

        /* Invert the list, so that largest/oldest file is first */

        worst_file_list = g_list_reverse(worst_file_list);

        /* And delete (some of) them */

        while (worst_file_list && cur_size > cap_size)

        {

            struct name_and_size *ns = worst_file_list->data;

            log_notice("%s is %.0f bytes (more than %.0f MB), deleting '%s' (%llu bytes)",

                    dir, cur_size, cap_size / (1024*1024), ns->name, (long long)ns->size);

            if (unlink(ns->name) != 0)

                perror_msg("Can't unlink '%s'", ns->name);

            else

                cur_size -= ns->size;

            free(ns);

            worst_file_list = g_list_delete_link(worst_file_list, worst_file_list);

        }

    }

}

int main(int argc, char **argv)

{

    /* I18n */

    setlocale(LC_ALL, "");

#if ENABLE_NLS

    bindtextdomain(PACKAGE, LOCALEDIR);

    textdomain(PACKAGE);

#endif

    abrt_init(argv);

    GList *dir_list = NULL;

    GList *file_list = NULL;

    char *preserve = NULL;

    /* Can't keep these strings/structs static: _() doesn't support that */

    const char *program_usage_string = _(

        "& [-v] [-d SIZE:DIR]... [-f SIZE:DIR]... [-p DIR] [FILE]...\n"

        "\n"

        "Deletes problem dirs (-d) or files (-f) in DIRs until they are smaller than SIZE.\n"

        "FILEs are preserved (never deleted)."

    );

    enum {

        OPT_v = 1 << 0,

        OPT_d = 1 << 1,

        OPT_f = 1 << 2,

        OPT_p = 1 << 3,

    };

    /* Keep enum above and order of options below in sync! */

    struct options program_options[] = {

        OPT__VERBOSE(&g_verbose),

        OPT_LIST('d'  , NULL, &dir_list , "SIZE:DIR", _("Delete whole problem directories")),

        OPT_LIST('f'  , NULL, &file_list, "SIZE:DIR", _("Delete files inside this directory")),

        OPT_STRING('p', NULL, &preserve,  "DIR"     , _("Preserve this directory")),

        OPT_END()

    };

    /*unsigned opts =*/ parse_opts(argc, argv, program_options, program_usage_string);

    argv += optind;

    if ((argv[0] && !file_list)

     || !(dir_list || file_list)

    ) {

        show_usage_and_die(program_usage_string, program_options);

    }

    /* We don't have children, so this is not needed: */

    //export_abrt_envvars(/*set_pfx:*/ 0);

    /* Preserve not only files specified on command line, but,

     * if they are symlinks, preserve also the real files they point to:

     */

    GList *preserve_files_list = NULL;

    while (*argv)

    {

        char *name = *argv++;

        /* Since we don't bother freeing preserve_files_list on exit,

         * we take a shortcut and insert name instead of xstrdup(name)

         * in the next line:

         */

        preserve_files_list = g_list_prepend(preserve_files_list, name);

        char *rp = realpath(name, NULL);

        if (rp)

        {

            if (strcmp(rp, name) != 0)

                preserve_files_list = g_list_prepend(preserve_files_list, rp);

            else

                free(rp);

        }

    }

    /* Not really necessary, but helps to reduce confusion when debugging */

    preserve_files_list = g_list_reverse(preserve_files_list);

    g_list_foreach(dir_list, delete_dirs, preserve);

    g_list_foreach(file_list, delete_files, preserve_files_list);

    return 0;

}