/*
 * This file is part of the Distributed Network Block Device 3
 *
 * Copyright(c) 2011-2012 Johann Latocha <johann@latocha.de>
 *
 * This file may be licensed under the terms of of the
 * GNU General Public License Version 2 (the ``GPL'').
 *
 * Software distributed under the License is distributed
 * on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
 * express or implied. See the GPL for the specific language
 * governing rights and limitations.
 *
 * You should have received a copy of the GPL along with this
 * program. If not, go to http://www.gnu.org/licenses/gpl.html
 * or write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <pthread.h>
#include <string.h>
#include <glib.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "server.h"
#include "utils.h"
#include "memlog.h"

/**
 * Parse IPv4 or IPv6 address in string representation to a suitable format usable by the BSD socket library
 * @string eg. "1.2.3.4" or "2a01::10:5", optially with port appended, eg "1.2.3.4:6666" or "2a01::10:5:6666"
 * @af will contain either AF_INET or AF_INET6
 * @addr will contain the address in network representation
 * @port will contain the port in network representation, defaulting to #define PORT if none was given
 * returns 1 on success, 0 in failure. contents of af, addr and port are undefined in the latter case
 */
static char parse_address(char *string, uint8_t *af, uint8_t *addr, uint16_t *port)
{
	struct in_addr v4;
	struct in6_addr v6;

	// Try IPv4 without port
	if (1 == inet_pton(AF_INET, string, &v4))
	{
		*af = AF_INET;
		memcpy(addr, &v4, 4);
		*port = htons(PORT);
		return 1;
	}
	// Try IPv6 without port
	if (1 == inet_pton(AF_INET6, string, &v6))
	{
		*af = AF_INET6;
		memcpy(addr, &v6, 16);
		*port = htons(PORT);
		return 1;
	}

	// Scan for port
	char *portpos = NULL, *ptr = string;
	while (*ptr)
	{
		if (*ptr == ':') portpos = ptr;
		++ptr;
	}
	if (portpos == NULL) return 0; // No port in string
	// Consider IP being surrounded by [ ]
	if (*string == '[' && *(portpos-1) == ']')
	{
		++string;
		*(portpos-1) = '\0';
	}
	*portpos++ = '\0';
	int p = atoi(portpos);
	if (p < 1 || p > 65535) return 0; // Invalid port
	*port = htons((uint16_t)p);

	// Try IPv4 with port
	if (1 == inet_pton(AF_INET, string, &v4))
	{
		*af = AF_INET;
		memcpy(addr, &v4, 4);
		return 1;
	}
	// Try IPv6 with port
	if (1 == inet_pton(AF_INET6, string, &v6))
	{
		*af = AF_INET6;
		memcpy(addr, &v6, 16);
		return 1;
	}

	// FAIL
	return 0;
}

static char is_valid_namespace(char *namespace)
{
	if (*namespace == '\0' || *namespace == '/') return 0; // Invalid: Length = 0 or starting with a slash
	while (*namespace)
	{
		if (*namespace != '/' && *namespace != '-'
				&& (*namespace < 'a' || *namespace > 'z')
				&& (*namespace < 'A' || *namespace > 'Z')) return 0;
		++namespace;
	}
	if (*(namespace - 1) == '/') return 0; // Invalid: Ends in a slash
	return 1;
}

static char is_valid_imagename(char *namespace)
{
	if (*namespace == '\0' || *namespace == ' ') return 0; // Invalid: Length = 0 or starting with a space
	while (*namespace)
	{	// Check for invalid chars
		if (*namespace != '.' && *namespace != '-' && *namespace != ' '
				&& *namespace != '(' && *namespace != ')'
				&& (*namespace < 'a' || *namespace > 'z')
				&& (*namespace < 'A' || *namespace > 'Z')) return 0;
		++namespace;
	}
	if (*(namespace - 1) == ' ') return 0; // Invalid: Ends in a space
	return 1;
}

static void strtolower(char *string)
{
	while (*string)
	{
		if (*string >= 'A' && *string <= 'Z') *string += 32;
		++string;
	}
}

void dnbd3_load_config(char *file)
{
    int fd;
    gint i, j, k;
    GKeyFile* gkf;

    gkf = g_key_file_new();
    if (!g_key_file_load_from_file(gkf, file, G_KEY_FILE_NONE, NULL))
    {
        printf("ERROR: Config file not found: %s\n", file);
        exit(EXIT_FAILURE);
    }

    char *namespace = g_key_file_get_string(gkf, "settings", "default_namespace", NULL);
    if (namespace && !is_valid_namespace(namespace))
    {
    	memlogf("[ERROR] Ignoring default namespace: '%s' is not a valid namespace", namespace);
    	g_free(namespace);
    	namespace = NULL;
    }

    gchar **groups = NULL;
    gsize section_count;
    groups = g_key_file_get_groups(gkf, &section_count);

    for (i = 0; i < section_count; i++)
    {
    	// Special group
    	if (strcmp(groups[i], "settings") == 0 || strcmp(groups[i], "trusted") == 0)
    	{
    		continue;
    	}

    	// An actual image definition

    	if (!is_valid_imagename(groups[i]))
    	{
    		memlogf("[ERROR] Invalid image name: '%s'", groups[i]);
    		continue;
    	}

    	int rid = g_key_file_get_integer(gkf, groups[i], "rid", NULL);
    	if (rid <= 0)
    	{
    		memlogf("[ERROR] Invalid rid '%d' for image '%s'", rid, groups[i]);
    		continue;
    	}

    	if (strchr(groups[i], '.') == NULL && namespace == NULL)
    	{
    		memlogf("[ERROR] Image '%s' has local name and no default namespace is defined; entry ignored.", groups[i]);
    		continue;
    	}

    	dnbd3_image_t *image = g_new0(dnbd3_image_t, 1);
    	if (image == NULL)
    	{
    		memlogf("[ERROR] Could not allocate dnbd3_image_t while reading config");
    		continue;
    	}

        if (strchr(groups[i], '/') == NULL)
        {	// Local image, build global name
        	image->name = calloc(strlen(namespace) + strlen(groups[i]) + 2, sizeof(char));
        	sprintf(image->name, "%s/%s", namespace, groups[i]);
        }
        else
        {
        	image->name = strdup(groups[i]);
        }

    	if (dnbd3_get_image(image->name, rid, 0))
    	{
    		memlogf("[ERROR] Duplicate image in config: '%s' rid:%d", image->name, rid);
    		free(image->name);
    		g_free(image);
    		continue;
    	}

        image->low_name = strdup(image->name);
        strtolower(image->low_name);

    	image->rid = rid;
    	image->file = g_key_file_get_string(gkf, groups[i], "file", NULL);
    	char relayed = image->file == NULL || *image->file == '\0';
    	if (relayed && image->file)
    	{
    		g_free(image->file);
    		image->file = NULL;
    	}

    	if (relayed)	// Image is relayed (this server acts as proxy)
    	{
    		if (strchr(groups[i], '.') == NULL)
    		{
    			memlogf("[ERROR] Relayed image without global name in config: '%s'", groups[i]);
    			g_free(image);
    			continue;
    		}
    		image->cache_file = g_key_file_get_string(gkf, groups[i], "cache", NULL);
    		if (image->cache_file && *image->cache_file == '\0') g_free(image->cache_file);
    	}
    	else	// Image is a local one, open file to get size
        {
			fd = open(image->file, O_RDONLY);
			if (fd > 0) {
				image->filesize = lseek(fd, 0, SEEK_END);
				if (image->filesize & 4095) {
					memlogf("[WARNING] Size of image '%s' is not a multiple of 4096. Last incomplete block will be ignored!", image->file);
					image->filesize &= ~(uint64_t)4095;
				}
				close(fd);
				image->working = 1;
			} else {
				memlogf("[ERROR] Image file not found: '%s'", image->file);
			}
        }

    	// A list of servers that are known to also host or relay this image
    	gsize num_servers;
        gchar **servers = g_key_file_get_string_list(gkf, groups[i], "servers", &num_servers, NULL);
        if (servers) for (k = 0, j = 0; j < MIN(num_servers, NUMBER_SERVERS); ++j)
        {
        	if (parse_address(servers[j], &(image->servers[k].hostaddrtype), image->servers[k].hostaddr, &(image->servers[k].port)))
        	{
        		++k; continue;
        	}
        	image->servers[k].hostaddrtype = 0;
        }
        g_strfreev(servers);

        if (image->cache_file)
        {
        	// Determine size of cached image
        	fd = open(image->cache_file, O_RDONLY);
        	if (fd > 0)
        	{
        		image->filesize = lseek(fd, 0, SEEK_END);
        		close(fd);
        	}
			if (image->filesize & 4095)
			{	// Cache files should always be trincated to 4kib boundaries already
				memlogf("[WARNING] Size of cache file '%s' is not a multiple of 4096. Something's fishy!", image->cache_file);
				image->filesize = 0;
			}
			else if (image->filesize > 0)
        	{
				const size_t map_len_bytes = (image->filesize + (1 << 15) - 1) >> 15;
				image->cache_map  = calloc(map_len_bytes, sizeof(uint8_t));
				// read cache map from file
				// one byte in the map covers 8 4kib blocks, so 32kib per byte
				// "+ (1 << 15) - 1" is required to account for the last bit of
				// the image that is smaller than 32kib
				// this would be the case whenever the image file size is not a
				// multiple of 32kib (= the number of blocks is not dividable by 8)
				// ie: if the image is 49152 bytes and you do 49152 >> 15 you get 1,
				// but you actually need 2 bytes to have a complete cache map
				char tmp[strlen(image->cache_file)+4];
				strcpy(tmp, image->cache_file);
				strcat(tmp, ".map");
				fd = open(tmp, O_RDONLY);
				if (fd > 0)
				{
					read(fd, image->cache_map, map_len_bytes * sizeof(uint8_t));
					close(fd);
					// If the whole image is cached, mark it as working right away without waiting for an upstream server
					image->working = 1;
					for (j = 0; j < map_len_bytes - 1; ++j)
					{
						if (image->cache_map[j] != 0xFF)
						{
							image->working = 0;
							break;
						}
					}
					const int blocks_in_last_byte = (image->filesize >> 12) & 7;
					uint8_t last_byte = 0;
					if (blocks_in_last_byte == 0)
						last_byte = 0xFF;
					else
						for (j = 0; j < k; ++j) last_byte = (last_byte << 1) | 1;
					if ((image->cache_map[map_len_bytes-1] & last_byte) != last_byte)
						image->working = 0;
					else
						memlogf("[INFO] Publishing relayed image '%s' because the local cache copy is complete", image->name);
				}

				/*
				// TODO: Do this as soon as a connection to a upstream server is established
				// open cache file
				fd = open(_images[i].cache_file, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
				if (fd < 1)
					memlogf("ERROR: Could't create cache file '%s'", _images[i].cache_file);

				if (_images[i].filesize != lseek(fd, 0, SEEK_END))
					fallocate(fd, 0, 0, _images[i].filesize);

				close(fd);
				*/
        	}
        } // end cache_file handling
        pthread_spin_lock(&_spinlock);
        _dnbd3_images = g_slist_append(_dnbd3_images, image);
        pthread_spin_unlock(&_spinlock);
        // DONE IMAGE
    }

    g_free(namespace);
    g_strfreev(groups);
    g_key_file_free(gkf);
}

int dnbd3_add_image(dnbd3_image_t *image, char *file)
{
	return ERROR_IMAGE_ALREADY_EXISTS; // TODO: Make it work with image names
	/*
	FILE* f = fopen(image->file,"r");
	if (f == NULL)
	{
		printf("ERROR: Image file not found: %s\n", image->file);
		return ERROR_FILE_NOT_FOUND;
	}
	fclose (f);

	dnbd3_image_t* tmp = dnbd3_get_image(image->vid, image->rid);
	if (image->rid == 0)
	{
		if(tmp)
			image->rid = tmp->rid +1;
		else
			image->rid = 1;
	} else if (tmp)
	{
		printf("ERROR: Image already exists (%d,%d)\n", image->vid, image->rid);
		return ERROR_IMAGE_ALREADY_EXISTS;
	}

    GKeyFile* gkf;
    gkf = g_key_file_new();
    if (!g_key_file_load_from_file(gkf, file, G_KEY_FILE_NONE, NULL))
    {
        printf("ERROR: Config file not found: %s\n", file);
        exit(EXIT_FAILURE);
    }

    g_key_file_set_integer(gkf, image->group, "vid", image->vid);
    g_key_file_set_integer(gkf, image->group, "rid", image->rid);
    g_key_file_set_string(gkf, image->group, "file", image->file);
    g_key_file_set_string(gkf, image->group, "servers", image->serverss);
    g_key_file_set_string(gkf, image->group, "cache", image->cache_file);

    gchar* data = g_key_file_to_data(gkf, NULL, NULL);

    f = fopen(file,"w");
    if (f)
    {
    	fputs((char*) data, f);
    	fclose(f);
        g_free(data);
        g_key_file_free(gkf);
        return 0;
    }
    else
    {
    	g_free(data);
    	g_key_file_free(gkf);
    	printf("ERROR: Config file is not writable: %s\n", file);
    	return ERROR_CONFIG_FILE_PERMISSIONS;
    }
    */
}

int dnbd3_del_image(dnbd3_image_t *image, char *file)
{
	return ERROR_IMAGE_NOT_FOUND; // TODO: Make it work with image names
	/*
	if (image->rid == 0)
	{
        printf("ERROR: Delete with rid=0 is not allowed\n");
        return ERROR_RID;
	}

	dnbd3_image_t* tmp = dnbd3_get_image(image->vid, image->rid);
	if (!tmp)
	{
        printf("ERROR: Image not found: (%d,%d)\n", image->vid, image->rid);
        return ERROR_IMAGE_NOT_FOUND;
	}

	GSList *iterator = NULL;
    for (iterator = _dnbd3_clients; iterator; iterator = iterator->next)
    {
        dnbd3_client_t *client = iterator->data;
        if (tmp == client->image)
        {
        	printf("ERROR: Delete is not allowed, image is in use (%d,%d)\n", tmp->vid, tmp->rid);
        	return ERROR_IMAGE_IN_USE;
        }
    }

    GKeyFile* gkf;
    gkf = g_key_file_new();
    if (!g_key_file_load_from_file(gkf, file, G_KEY_FILE_NONE, NULL))
    {
        printf("ERROR: Config file not found: %s\n", file);
        exit(EXIT_FAILURE);
    }

    g_key_file_remove_group(gkf, tmp->group, NULL);
    gchar* data = g_key_file_to_data(gkf, NULL, NULL);

    FILE* f = fopen(file,"w");
    if (f)
    {
    	fputs((char*) data, f);
    	fclose(f);
        g_free(data);
        g_key_file_free(gkf);
        // TODO: unlink image file
        return 0;
    }
    else
    {
    	g_free(data);
    	g_key_file_free(gkf);
    	printf("ERROR: Config file is not writable: %s\n", file);
    	return ERROR_CONFIG_FILE_PERMISSIONS;
    }
    */
}

dnbd3_image_t* dnbd3_get_image(char *name_orig, int rid, const char do_lock)
{
    dnbd3_image_t *result = NULL, *image;
	GSList *iterator;
	char name[strlen(name_orig) + 1];
	strcpy(name, name_orig);
	strtolower(name);
    if (do_lock) pthread_spin_lock(&_spinlock);
    for (iterator = _dnbd3_images; iterator; iterator = iterator->next)
    {
        image = iterator->data;
        if (rid != 0) // rid was specified
        {
            if (image->rid == rid && strcmp(name, image->low_name) == 0)
            {
                result = image;
                break;
            }
        }
        else // search max. rid available
        {
            if (strcmp(name, image->low_name) == 0 && (result == NULL || result->rid < image->rid))
            {
                result = image;
            }
        }
    }
    if (do_lock) pthread_spin_unlock(&_spinlock);
    return result;
}

void dnbd3_handle_sigpipe(int signum)
{
    memlogf("ERROR: SIGPIPE received!\n");
}

void dnbd3_handle_sigterm(int signum)
{
    memlogf("INFO: SIGTERM or SIGINT received!\n");
    dnbd3_cleanup();
}