/*
  Copyright 2012 Alexandre Rostovtsev

  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:

  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <libdaemon/dfork.h>

#include <glib.h>
#include <gio/gio.h>
#include <polkit/polkit.h>

#include "utils.h"

#include "config.h"

static GRegex *indent_regex = NULL;
static GRegex *comment_regex = NULL;
static GRegex *separator_regex = NULL;
static GRegex *var_equals_regex = NULL;
static GRegex *single_quoted_regex = NULL;
static GRegex *double_quoted_regex = NULL;
static GRegex *unquoted_regex = NULL;

/* Always returns TRUE */
gboolean
_g_match_info_clear (GMatchInfo **match_info)
{
    if (match_info == NULL || *match_info == NULL)
        return TRUE;
    g_match_info_free (*match_info);
    *match_info = NULL;
    return TRUE;
}

gchar *
strstr0 (const gchar *haystack, const gchar *needle)
{
    if (haystack == NULL || needle == NULL)
        return NULL;
    return strstr (haystack, needle);
}

struct check_polkit_data {
    const gchar *unique_name;
    const gchar *action_id;
    gboolean user_interaction;
    GAsyncReadyCallback callback;
    gpointer user_data;

    PolkitAuthority *authority;
    PolkitSubject *subject;
};

void
check_polkit_data_free (struct check_polkit_data *data)
{
    if (data == NULL)
        return;

    if (data->subject != NULL)
        g_object_unref (data->subject);
    if (data->authority != NULL)
        g_object_unref (data->authority);
    
    g_free (data);
}

gboolean
check_polkit_finish (GAsyncResult *res,
                     GError **error)
{
    GSimpleAsyncResult *simple;

    simple = G_SIMPLE_ASYNC_RESULT (res);
    if (g_simple_async_result_propagate_error (simple, error))
        return FALSE;

    return g_simple_async_result_get_op_res_gboolean (simple);
}

static void
check_polkit_authorization_cb (GObject *source_object,
                               GAsyncResult *res,
                               gpointer _data)
{
    struct check_polkit_data *data;
    PolkitAuthorizationResult *result;
    GSimpleAsyncResult *simple;
    GError *err = NULL;

    data = (struct check_polkit_data *) _data;
    if ((result = polkit_authority_check_authorization_finish (data->authority, res, &err)) == NULL) {
        g_simple_async_report_take_gerror_in_idle (NULL, data->callback, data->user_data, err);
        goto out;
    }
 
    if (!polkit_authorization_result_get_is_authorized (result)) {
        g_simple_async_report_error_in_idle (NULL, data->callback, data->user_data, POLKIT_ERROR, POLKIT_ERROR_NOT_AUTHORIZED, "Authorizing for '%s': not authorized", data->action_id);
        goto out;
    }
    simple = g_simple_async_result_new (NULL, data->callback, data->user_data, check_polkit_async);
    g_simple_async_result_set_op_res_gboolean (simple, TRUE);
    g_simple_async_result_complete_in_idle (simple);
    g_object_unref (simple);

  out:
    check_polkit_data_free (data);
    if (result != NULL)
        g_object_unref (result);
}

static void
check_polkit_authority_cb (GObject *source_object,
                           GAsyncResult *res,
                           gpointer _data)
{
    struct check_polkit_data *data;
    GError *err = NULL;

    data = (struct check_polkit_data *) _data;
    if ((data->authority = polkit_authority_get_finish (res, &err)) == NULL) {
        g_simple_async_report_take_gerror_in_idle (NULL, data->callback, data->user_data, err);
        check_polkit_data_free (data);
        return;
    }
    if (data->unique_name == NULL || data->action_id == NULL || 
        (data->subject = polkit_system_bus_name_new (data->unique_name)) == NULL) {
        g_simple_async_report_error_in_idle (NULL, data->callback, data->user_data, POLKIT_ERROR, POLKIT_ERROR_FAILED, "Authorizing for '%s': failed sanity check", data->action_id);
        check_polkit_data_free (data);
        return;
    }
    polkit_authority_check_authorization (data->authority, data->subject, data->action_id, NULL, (PolkitCheckAuthorizationFlags) data->user_interaction, NULL, check_polkit_authorization_cb, data);
}

void
check_polkit_async (const gchar *unique_name,
                    const gchar *action_id,
                    const gboolean user_interaction,
                    GAsyncReadyCallback callback,
                    gpointer user_data)
{
    struct check_polkit_data *data;

    data = g_new0 (struct check_polkit_data, 1);
    data->unique_name = unique_name;
    data->action_id = action_id;
    data->user_interaction = user_interaction;
    data->callback = callback;
    data->user_data = user_data;

    polkit_authority_get_async (NULL, check_polkit_authority_cb, data);
}

enum ShellEntryType {
    SHELL_ENTRY_TYPE_INDENT,
    SHELL_ENTRY_TYPE_COMMENT,
    SHELL_ENTRY_TYPE_SEPARATOR,
    SHELL_ENTRY_TYPE_ASSIGNMENT,
};

struct ShellEntry {
    enum ShellEntryType type;
    gchar *string;
    gchar *variable; /* only relevant for assignments */
    gchar *unquoted_value; /* only relevant for assignments */
};

gchar *
shell_source_var (GFile *file,
                  const gchar *variable,
                  GError **error)
{
    gchar *argv[4] = { "sh", "-c", NULL, NULL };
    gchar *filename = NULL, *quoted_filename = NULL;
    gchar *output = NULL;
    GFileInfo *info;
    const GFileAttributeInfo *attribute_info;

    filename = g_file_get_path (file);
    if ((info = g_file_query_info (file, G_FILE_ATTRIBUTE_STANDARD_TYPE "," G_FILE_ATTRIBUTE_ACCESS_CAN_READ, G_FILE_QUERY_INFO_NONE, NULL, error)) == NULL) {
        g_prefix_error (error, "Unable to source '%s': ", filename);
        goto out;
    }

    if (g_file_info_get_file_type (info) != G_FILE_TYPE_REGULAR &&
        g_file_info_get_file_type (info) != G_FILE_TYPE_SYMBOLIC_LINK) {
        g_propagate_error (error,
                           g_error_new (G_FILE_ERROR, G_FILE_ERROR_FAILED,
                                        "Unable to source '%s': not a regular file", filename));
        goto out;
    }

    if (!g_file_info_get_attribute_boolean (info, G_FILE_ATTRIBUTE_ACCESS_CAN_READ)) {
        g_propagate_error (error,
                           g_error_new (G_FILE_ERROR, G_FILE_ERROR_ACCES,
                                        "Unable to source '%s': permission denied", filename));
        goto out;
    }

    quoted_filename = g_shell_quote (filename);
    argv[2] = g_strdup_printf (". %s; echo -n %s", quoted_filename, variable);

    if (!g_spawn_sync (NULL, argv, NULL, G_SPAWN_SEARCH_PATH, NULL, NULL, &output, NULL, NULL, error)) {
        g_prefix_error (error, "Unable to source '%s': ", filename);
    }

  out:
    g_free (filename);
    g_free (quoted_filename);
    if (info != NULL)
        g_object_unref (info);
    if (argv[2] != NULL)
        g_free (argv[2]);
    return output;
}

static void
shell_entry_free (struct ShellEntry *entry)
{
    if (entry == NULL)
        return;

    g_free (entry->string);
    g_free (entry->variable);
    g_free (entry->unquoted_value);
    g_free (entry);
}

void
shell_parser_free (ShellParser *parser)
{
    if (parser == NULL)
        return;

    if (parser->file != NULL)
        g_object_unref (parser->file);
    if (parser->filename != NULL)
        g_free (parser->filename);
    if (parser->entry_list != NULL)
        g_list_free_full (parser->entry_list, (GDestroyNotify)shell_entry_free);
    g_free (parser);
}

ShellParser *
shell_parser_new (GFile *file,
                  GError **error)
{
    gchar *filebuf = NULL;
    GError *local_err = NULL;
    ShellParser *ret = NULL;

    if (file == NULL)
        return NULL;

    if (!g_file_load_contents (file, NULL, &filebuf, NULL, NULL, &local_err)) {
        if (local_err != NULL) {
            /* Inability to parse or open is a failure; file not existing at all is *not* a failure */
            if (local_err->code == G_IO_ERROR_NOT_FOUND) {
                g_error_free (local_err);
                ret = g_new0 (ShellParser, 1);
                g_object_ref (file);
                ret->file = file;
                ret->filename = g_file_get_path (file);
                return ret;
            } else {
                gchar *filename;
                filename = g_file_get_path (file);
                g_propagate_prefixed_error (error, local_err, "Unable to read '%s':", filename);
                g_free (filename);
            }
        }
        return NULL;
    }
    ret = shell_parser_new_from_string (file, filebuf, error);
    g_free (filebuf);
    return ret;
}

ShellParser *
shell_parser_new_from_string (GFile *file,
                                     gchar *filebuf,
                                     GError **error)
{
    ShellParser *ret = NULL;
    GError *local_err = NULL;
    gchar *s;

    if (file == NULL || filebuf == NULL)
        return NULL;

    ret = g_new0 (ShellParser, 1);
    g_object_ref (file);
    ret->file = file;
    ret->filename = g_file_get_path (file);

    gboolean want_separator = FALSE; /* Do we expect the next entry to be a separator or comment? */
    s = filebuf;
    while (*s != 0) {
        g_debug ("Scanning string: ``%s''", s);
        gboolean matched = FALSE;
        GMatchInfo *match_info = NULL;
        struct ShellEntry *entry = NULL;
 
        matched = g_regex_match (comment_regex, s, 0, &match_info);
        if (matched) {
            entry = g_new0 (struct ShellEntry, 1);
            entry->type = SHELL_ENTRY_TYPE_COMMENT;
            entry->string = g_match_info_fetch (match_info, 0);
            ret->entry_list = g_list_prepend (ret->entry_list, entry);
            s += strlen (entry->string);
            g_debug ("Scanned comment: ``%s''", entry->string);
            _g_match_info_clear (&match_info);
            want_separator = FALSE;
            continue;
        }
        _g_match_info_clear (&match_info);

        matched = g_regex_match (separator_regex, s, 0, &match_info);
        if (matched) {
            entry = g_new0 (struct ShellEntry, 1);
            entry->type = SHELL_ENTRY_TYPE_SEPARATOR;
            entry->string = g_match_info_fetch (match_info, 0);
            ret->entry_list = g_list_prepend (ret->entry_list, entry);
            s += strlen (entry->string);
            g_debug ("Scanned separator: ``%s''", entry->string);
            _g_match_info_clear (&match_info);
            want_separator = FALSE;
            continue;
        }
        _g_match_info_clear (&match_info);

        matched = g_regex_match (indent_regex, s, 0, &match_info);
        if (matched) {
            entry = g_new0 (struct ShellEntry, 1);
            entry->type = SHELL_ENTRY_TYPE_INDENT;
            entry->string = g_match_info_fetch (match_info, 0);
            ret->entry_list = g_list_prepend (ret->entry_list, entry);
            s += strlen (entry->string);
            g_debug ("Scanned indent: ``%s''", entry->string);
            _g_match_info_clear (&match_info);
            continue;
        }
        _g_match_info_clear (&match_info);

        matched = g_regex_match (var_equals_regex, s, 0, &match_info);
        if (matched) {
            gchar *raw_value = NULL, *temp1 = NULL, *temp2 = NULL;
            /* If we expect a separator and get an assignment instead, fail */
            if (want_separator)
                goto no_match;

            entry = g_new0 (struct ShellEntry, 1);
            entry->type = SHELL_ENTRY_TYPE_ASSIGNMENT;
            entry->string = g_match_info_fetch (match_info, 0);
            entry->variable = g_match_info_fetch (match_info, 1);
            s += strlen (entry->string);
            g_debug ("Scanned variable: ``%s''", entry->string);
            _g_match_info_clear (&match_info);
            want_separator = TRUE;

            while (*s != 0) {
                g_debug ("Scanning string for values: ``%s''", s);
                gboolean matched2 = FALSE;

                matched2 = g_regex_match (single_quoted_regex, s, 0, &match_info);
                if (matched2)
                    goto append_value;

                _g_match_info_clear (&match_info);

                matched2 = g_regex_match (double_quoted_regex, s, 0, &match_info);
                if (matched2)
                    goto append_value;

                _g_match_info_clear (&match_info);

                matched2 = g_regex_match (unquoted_regex, s, 0, &match_info);
                if (matched2)
                    goto append_value;

                _g_match_info_clear (&match_info);

                break;

  append_value:
                if (raw_value == NULL) {
                    raw_value = g_match_info_fetch (match_info, 0);
                    s += strlen (raw_value);
                    g_debug ("Scanned value: ``%s''", raw_value);
                } else {
                    temp1 = raw_value;
                    temp2 = g_match_info_fetch (match_info, 0);
                    raw_value = g_strconcat (temp1, temp2, NULL);
                    s += strlen (temp2);
                    g_debug ("Scanned value: ``%s''", temp2);
                    g_free (temp1);
                    g_free (temp2);
                }
                _g_match_info_clear (&match_info);
            }

            if (raw_value != NULL) {
                entry->unquoted_value = g_shell_unquote (raw_value, &local_err);
                g_debug  ("Unquoted value: ``%s''", entry->unquoted_value);
                temp1 = entry->string;
                temp2 = raw_value;
                entry->string = g_strconcat (temp1, temp2, NULL);
                g_free (temp1);
                g_free (temp2);
                ret->entry_list = g_list_prepend (ret->entry_list, entry);
                if (local_err != NULL)
                    goto no_match;
            }
            continue;
        }

  no_match:
        /* Nothing matches, parsing has failed! */
        _g_match_info_clear (&match_info);
        if (local_err != NULL)
            g_propagate_prefixed_error (error, local_err, "Unable to parse '%s':", ret->filename);
        else
            g_propagate_error (error,
                               g_error_new (G_FILE_ERROR, G_FILE_ERROR_FAILED,
                                            "Unable to parse '%s'", ret->filename));
        shell_parser_free (ret);
        return NULL;
    }

    ret->entry_list = g_list_reverse (ret->entry_list);
    return ret;
}

gboolean
shell_parser_is_empty (ShellParser *parser)
{
    if (parser == NULL || parser->entry_list == NULL)
        return TRUE;
    return FALSE;
}

gboolean
shell_parser_set_variable (ShellParser *parser,
                           const gchar *variable,
                           const gchar *value,
                           gboolean add_if_unset)
{
    GList *curr = NULL;
    struct ShellEntry *found_entry = NULL;
    gchar *quoted_value = NULL;
    gboolean ret = FALSE;

    g_assert (parser != NULL);
    g_assert (variable != NULL);

    for (curr = parser->entry_list; curr != NULL; curr = curr->next) {
        struct ShellEntry *entry;

        entry = (struct ShellEntry *)(curr->data);
        if (entry->type == SHELL_ENTRY_TYPE_ASSIGNMENT && g_strcmp0 (variable, entry->variable) == 0)
            found_entry = entry;
    }

    quoted_value = g_shell_quote (value);

    if (found_entry != NULL) {
        g_free (found_entry->string);
        found_entry->string = g_strdup_printf ("%s=%s", variable, quoted_value);
        ret = TRUE;
    } else {
        if (add_if_unset) {
            found_entry = g_new0 (struct ShellEntry, 1);
            found_entry->type = SHELL_ENTRY_TYPE_ASSIGNMENT;
            found_entry->variable = g_strdup (variable);
            found_entry->string = g_strdup_printf ("%s=%s", variable, quoted_value);
            parser->entry_list = g_list_append (parser->entry_list, found_entry);
            ret = TRUE;
        }
    }

    g_free (quoted_value);
    return ret;
}

void
shell_parser_clear_variable (ShellParser *parser,
                             const gchar *variable)
{
    GList *curr = NULL;
    gboolean ret = FALSE;

    g_assert (parser != NULL);
    g_assert (variable != NULL);

    for (curr = parser->entry_list; curr != NULL; ) {
        struct ShellEntry *entry;

        entry = (struct ShellEntry *)(curr->data);
        if (entry->type == SHELL_ENTRY_TYPE_ASSIGNMENT && g_strcmp0 (variable, entry->variable) == 0) {
            GList *prev, *next;

            prev = curr->prev;
            next = curr->next;
            curr->prev = NULL;
            curr->next = NULL;
            g_list_free_full (curr, (GDestroyNotify)shell_entry_free);
            if (prev != NULL)
                prev->next = next;
            if (next != NULL)
                next->prev = prev;
            curr = next;
        } else
            curr = curr->next;
    }
}

gboolean
shell_parser_save (ShellParser *parser,
                   GError **error)
{
    gboolean ret = FALSE;
    GList *curr = NULL;
    GFileOutputStream *os;

    g_assert (parser != NULL && parser->file != NULL && parser->filename != NULL);
    if ((os = g_file_replace (parser->file, NULL, FALSE, G_FILE_CREATE_NONE, NULL, error)) == NULL) {
        g_prefix_error (error, "Unable to save '%s': ", parser->filename);
        goto out;
    }

    for (curr = parser->entry_list; curr != NULL; curr = curr->next) {
        struct ShellEntry *entry;
        gsize written;

        entry = (struct ShellEntry *)(curr->data);
        if (!g_output_stream_write_all (G_OUTPUT_STREAM (os), entry->string, strlen (entry->string), &written, NULL, error)) {
            g_prefix_error (error, "Unable to save '%s': ", parser->filename);
            goto out;
        }
    }
    
    if (!g_output_stream_close (G_OUTPUT_STREAM (os), NULL, error)) {
        g_prefix_error (error, "Unable to save '%s': ", parser->filename);
        g_output_stream_close (G_OUTPUT_STREAM (os), NULL, NULL);
        goto out;
    }
    ret = TRUE;

  out:
    if (os)
        g_object_unref (os);
    return ret;
}

gboolean
shell_parser_set_and_save (GFile *file,
                           GError **error,
                           const gchar *first_var_name,
                           const gchar *first_alt_var_name,
                           const gchar *first_value,
                           ...)
{
    va_list ap;
    ShellParser *parser;
    gboolean ret = FALSE;
    const gchar *var_name, *alt_var_name, *value;

    va_start (ap, first_value);
    if ((parser = shell_parser_new (file, error)) == NULL)
        goto out;

    var_name = first_var_name;
    alt_var_name = first_alt_var_name;
    value = first_value;
    do {
        if (alt_var_name == NULL) {
            if (!shell_parser_set_variable (parser, var_name, value, TRUE)) {
                g_propagate_error (error,
                        g_error_new (G_FILE_ERROR, G_FILE_ERROR_FAILED,
                                    "Unable to set %s in '%s'", var_name, parser->filename));
                goto out;
            }
        } else {
            if (!shell_parser_set_variable (parser, var_name, value, FALSE) &&
                !shell_parser_set_variable (parser, alt_var_name, value, FALSE) &&
                !shell_parser_set_variable (parser, var_name, value, TRUE)) {
                    g_propagate_error (error,
                            g_error_new (G_FILE_ERROR, G_FILE_ERROR_FAILED,
                                        "Unable to set %s or %s in '%s'", var_name, alt_var_name, parser->filename));
                    goto out;
            }
        }
    } while ((var_name = va_arg (ap, const gchar*)) != NULL ?
                 alt_var_name = va_arg (ap, const gchar*), value = va_arg (ap, const gchar*), 1 : 0);

    if (!shell_parser_save (parser, error))
        goto out;

    ret = TRUE;

  out:
    va_end (ap);
    if (parser != NULL)
        shell_parser_free (parser);
    return ret;
}

gchar **
shell_parser_source_var_list (GFile *file,
                              const gchar * const *var_names,
                              GError **error)
{
    ShellParser *parser;
    gchar **ret = NULL, **value;
    const gchar* const* var_name;

    if (var_names == NULL)
        return NULL;

    if ((parser = shell_parser_new (file, error)) == NULL)
        return NULL;

    ret = g_new0 (gchar *, g_strv_length ((gchar **)var_names) + 1);
    for (var_name = var_names, value = ret; *var_name != NULL; var_name++, value++) {
        GList *curr;
        for (curr = parser->entry_list; curr != NULL; curr = curr->next) {
            struct ShellEntry *entry;

            entry = (struct ShellEntry *)(curr->data);
            if (entry->type == SHELL_ENTRY_TYPE_ASSIGNMENT && g_strcmp0 (*var_name, entry->variable) == 0)
                *value = g_strdup (entry->unquoted_value);
        }
    }
    shell_parser_free (parser);
    return ret;
}

void
utils_destroy (void)
{
    if (indent_regex != NULL) {
        g_regex_unref (indent_regex);
        indent_regex = NULL;
    }
    if (comment_regex != NULL) {
        g_regex_unref (comment_regex);
        comment_regex = NULL;
    }
    if (separator_regex != NULL) {
        g_regex_unref (separator_regex);
        separator_regex = NULL;
    }
    if (var_equals_regex != NULL) {
        g_regex_unref (var_equals_regex);
        var_equals_regex = NULL;
    }
    if (single_quoted_regex != NULL) {
        g_regex_unref (single_quoted_regex);
        single_quoted_regex = NULL;
    }
    if (double_quoted_regex != NULL) {
        g_regex_unref (double_quoted_regex);
        double_quoted_regex = NULL;
    }
    if (unquoted_regex != NULL) {
        g_regex_unref (unquoted_regex);
        unquoted_regex = NULL;
    }
}

void
utils_init (void)
{
    if (indent_regex == NULL) {
        indent_regex = g_regex_new ("^[ \\t]+", G_REGEX_ANCHORED, 0, NULL);
        g_assert (indent_regex != NULL);
    }
    if (comment_regex == NULL) {
        comment_regex = g_regex_new ("^#[^\\n]*\\n", G_REGEX_ANCHORED|G_REGEX_MULTILINE, 0, NULL);
        g_assert (comment_regex != NULL);
    }
    if (separator_regex == NULL) {
        separator_regex = g_regex_new ("^[ \\t;\\n\\r]*[;\\n][ \\t;\\n\\r]*", G_REGEX_ANCHORED|G_REGEX_MULTILINE, 0, NULL);
        g_assert (separator_regex != NULL);
    }
    if (var_equals_regex == NULL) {
        var_equals_regex = g_regex_new ("^([a-zA-Z_][a-zA-Z0-9_]*)(?:(?:\\\\\\n)*)=(?:(?:\\\\\\n)*)", G_REGEX_ANCHORED|G_REGEX_MULTILINE, 0, NULL);
        g_assert (var_equals_regex != NULL);
    }
    if (single_quoted_regex == NULL) {
        single_quoted_regex = g_regex_new ("^'[^']*'", G_REGEX_ANCHORED|G_REGEX_MULTILINE, 0, NULL);
        g_assert (single_quoted_regex != NULL);
    }
    /* We do not want to allow $(...) or `...` constructs in double-quoted
     * strings because they might have side effects, but ${...} is OK */
    if (double_quoted_regex == NULL) {
        double_quoted_regex = g_regex_new ("^\"(?:[^\"`\\$]|\\\\[\"`\\$]|\\$\\{)*\"", G_REGEX_ANCHORED|G_REGEX_MULTILINE, 0, NULL);
        g_assert (double_quoted_regex != NULL);
    }
    if (unquoted_regex == NULL) {
        unquoted_regex = g_regex_new ("^(?:[^\\s\"'`\\$\\|&<>;]|\\\\[\\s\"'`\\$\\|&<>;]|\\$\\{)+", G_REGEX_ANCHORED|G_REGEX_MULTILINE, 0, NULL);
        g_assert (unquoted_regex != NULL);
    }
}