/*
 * 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"

// Keep parsed config file in memory so it doesn't need to be parsed again every time it's modified
static GKeyFile* _config_handle = NULL;

static char parse_address(char *string, uint8_t *af, uint8_t *addr, uint16_t *port);
static char is_valid_namespace(char *namespace);
static char is_valid_imagename(char *namespace);
static void strtolower(char *string);
static dnbd3_image_t* prepare_image(char *image_name, int rid, char *image_file, char *cache_file, gchar **servers, gsize num_servers);
static int save_config();
//static char* get_local_image_name(char *global_name);

/**
 * 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()
{
	gint i;

	if (_config_handle != NULL)
	{
		printf("dnbd3_load_config() called more than once\n\n");
		exit(EXIT_FAILURE);
	}

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

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

	_ipc_password = g_key_file_get_string(_config_handle, "settings", "password", NULL);

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

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

		// An actual image definition

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

		const time_t delsoft = g_key_file_get_int64(_config_handle, groups[i], "delete_soft", NULL);
		const time_t delhard = g_key_file_get_int64(_config_handle, groups[i], "delete_hard", NULL);
		if ((delsoft != 0 && delsoft < time(NULL)) || (delhard != 0 && delhard < time(NULL)))
		{
			memlogf("[INFO] Ignoring image '%s' as its deletion is due", groups[i]);
			continue;
		}

		char *image_file = g_key_file_get_string(_config_handle, groups[i], "file", NULL);
		char *cache_file = g_key_file_get_string(_config_handle, groups[i], "cache", NULL);
		gsize num_servers;
		gchar **servers = g_key_file_get_string_list(_config_handle, groups[i], "servers", &num_servers, NULL);

		pthread_spin_lock(&_spinlock);
		dnbd3_image_t *image = prepare_image(groups[i], rid, image_file, cache_file, servers, num_servers);
		if (image)
		{
			_dnbd3_images = g_slist_prepend(_dnbd3_images, image);
		}
		pthread_spin_unlock(&_spinlock);

		g_free(image_file);
		g_free(cache_file);
		g_strfreev(servers);
	}

	g_strfreev(groups);
}

int dnbd3_add_image(dnbd3_image_t *image)
{
	// Lock here to prevent concurrent add calls to mess rids up. Cannot happen currently
	// as IPC clients are not threaded and they're the only place where this is called,
	// but better be safe for the future...
	pthread_spin_lock(&_spinlock);
	if (image->rid == 0)
	{
		const dnbd3_image_t *latest = dnbd3_get_image(image->config_group, 0, 0);
		if (latest)
			image->rid = latest->rid + 1;
		else
			image->rid = 1;
	}

	dnbd3_image_t *newimage = prepare_image(image->config_group, image->rid, image->file, image->cache_file, NULL, 0);
	if (newimage)
	{
		_dnbd3_images = g_slist_prepend(_dnbd3_images, image);
	}
	else
	{
		pthread_spin_unlock(&_spinlock);
		return ERROR_SEE_LOG;
	}

	// Adding image was successful, write config file
	 g_key_file_set_integer(_config_handle, image->config_group, "rid", image->rid);
	 g_key_file_set_string(_config_handle, image->config_group, "file", image->file);
	 //g_key_file_set_string(_config_handle, image->name, "servers", image->serverss); // TODO: Save servers as string
	 g_key_file_set_string(_config_handle, image->config_group, "cache", image->cache_file);

	 pthread_spin_unlock(&_spinlock);

	 const int ret = save_config();
	 if (ret == ERROR_OK)
		 memlogf("[INFO] Added new image '%s' (rid %d)", newimage->config_group, newimage->rid);
	 else
		 memlogf("[INFO] Added new image '%s' (rid %d), but config file could not be written (%s)", newimage->config_group, newimage->rid, _config_file_name);
	 return ret;
}

int dnbd3_del_image(dnbd3_image_t *image)
{
	if (image->rid <= 0) // Require a specific rid on deletion
		return ERROR_RID;
	pthread_spin_lock(&_spinlock);
	dnbd3_image_t *existing_image = dnbd3_get_image(image->config_group, image->rid, 0);
	if(existing_image == NULL)
	{
		pthread_spin_unlock(&_spinlock);
		return ERROR_IMAGE_NOT_FOUND;
	}

	existing_image->delete_soft = 1; // TODO: Configurable.
	existing_image->delete_hard = time(NULL) + 86400; // TODO: Configurable
	g_key_file_set_int64(_config_handle, image->config_group, "delete_soft", existing_image->delete_soft);
	g_key_file_set_int64(_config_handle, image->config_group, "delete_hard", existing_image->delete_hard);

	pthread_spin_unlock(&_spinlock);
	dnbd3_exec_delete(FALSE);
	existing_image = NULL;

	 const int ret = save_config();
	 if (ret == ERROR_OK)
		 memlogf("[INFO] Marked for deletion: '%s' (rid %d)", image->config_group, image->rid);
	 else
		 memlogf("[WARNING] Marked for deletion: '%s' (rid %d), but config file could not be written (%s)", image->config_group, image->rid, _config_file_name);
	 return ret;
}

static int save_config()
{
	pthread_spin_lock(&_spinlock);
	 char* data = (char*)g_key_file_to_data(_config_handle, NULL, NULL);
	 if (data == NULL)
	 {
		 pthread_spin_unlock(&_spinlock);
		 memlogf("[ERROR] g_key_file_to_data() failed");
		 return ERROR_UNSPECIFIED_ERROR;
	 }

	 FILE *f = fopen(_config_file_name, "w");
	 if (f < 0)
	 {
		 pthread_spin_unlock(&_spinlock);
		 g_free(data);
		 return ERROR_CONFIG_FILE_PERMISSIONS;
	 }
	 fputs("# Do not edit this file while dnbd3-server is running\n", f);
	 fputs(data, f);
	 fclose(f);
	 pthread_spin_unlock(&_spinlock);
	 g_free(data);
	 return 0;
}

dnbd3_image_t* dnbd3_get_image(char *name_orig, int rid, const char do_lock)
{
	dnbd3_image_t *result = NULL, *image;
	GSList *iterator;
	// For comparison, make sure the name is global and lowercased
	int slen;
	int islocal = (strchr(name_orig, '/') == NULL);
	if (islocal)
		slen = strlen(name_orig) + strlen(_local_namespace) + 2;
	else
		slen = strlen(name_orig) + 1;
	char name[slen];
	if (islocal)
		sprintf(name, "%s/%s", _local_namespace, name_orig);
	else
		strcpy(name, name_orig);
	strtolower(name);
	// Now find the image
	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();
}

/**
 * Prepare image to be added to image list. Returns a pointer to a newly allocated image struct
 * on success, NULL otherwise.
 * Note: This function calls dnbd3_get_image without locking, so make sure you lock
 * before calling this function while the server is active.
 */
static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file, char *cache_file, gchar **servers, gsize num_servers)
{
	int j, k;
	if (image_name == NULL)
	{
		memlogf("[ERROR] Null Image-Name");
		return NULL;
	}
	if (!is_valid_imagename(image_name))
	{
		memlogf("[ERROR] Invalid image name: '%s'", image_name);
		return NULL;
	}

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

	// Allocate image struct and zero it out by using g_new0
	dnbd3_image_t *image = g_new0(dnbd3_image_t, 1);
	if (image == NULL)
	{
		memlogf("[ERROR] Could not allocate dnbd3_image_t while reading config");
		return NULL;
	}

	if (strchr(image_name, '/') == NULL)
	{	// Local image, build global name
		image->low_name = calloc(strlen(_local_namespace) + strlen(image_name) + 2, sizeof(char));
		sprintf(image->low_name, "%s/%s", _local_namespace, image_name);
	}
	else
	{
		image->low_name = strdup(image_name);
	}

	if (dnbd3_get_image(image->low_name, rid, 0))
	{
		memlogf("[ERROR] Duplicate image in config: '%s' rid:%d", image_name, rid);
		goto error;
	}

	strtolower(image->low_name);
	image->config_group = strdup(image_name);

	image->rid = rid;
	image->relayed = (image_file == NULL || image_file == '\0');

	if (image->relayed)	// Image is relayed (this server acts as proxy)
	{
		if (strchr(image_name, '/') == NULL)
		{
			memlogf("[ERROR] Relayed image without global name in config: '%s'", image_name);
			goto error;
		}
		if (cache_file && *cache_file)
			image->cache_file = strdup(cache_file);
	}
	else	// Image is a local one, open file to get size
	{
		image->file = strdup(image_file);
		int fd = open(image->file, O_RDONLY);
		if (fd < 0)
		{
			memlogf("[ERROR] Image file not found: '%s'", image->file);
			goto error;
		}
		const off_t size = lseek(fd, 0, SEEK_END);
		if (size <= 0)
		{
			memlogf("[ERROR] File '%s' of image '%s' has size '%lld'. Image ignored.",
				image->file, image_name, (long long)size);
			goto error;
		}
		image->filesize = (uint64_t)size;
		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;
	}

	// A list of servers that are known to also host or relay this image
	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;
		}

	if (image->cache_file)
	{
		// Determine size of cached image
		int fd = open(image->cache_file, O_RDONLY);
		if (fd >= 0)
		{
			const off_t size = lseek(fd, 0, SEEK_END);
			if (size > 0)
				image->filesize = (uint64_t)size;
			close(fd);
		}
		if (image->filesize & 4095)
		{	// Cache files should always be truncated 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 = IMGSIZE_TO_MAPBYTES(image->filesize);
			image->cache_map = calloc(map_len_bytes, sizeof(uint8_t));
			// read cache map from file
			char tmp[strlen(image->cache_file) + 5];
			strcpy(tmp, image->cache_file);
			strcat(tmp, ".map");
			fd = open(tmp, O_RDONLY);
			if (fd >= 0)
			{
				const off_t size = lseek(fd, 0, SEEK_END);
				if (size != map_len_bytes)
				{
					memlogf("[DEBUG] Cache-Map of %s is corrupted (%d != %d)", image_name, (int)size, (int)map_len_bytes);
				}
				else
				{
					lseek(fd, 0, SEEK_SET);
					read(fd, image->cache_map, map_len_bytes);
					// 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 < blocks_in_last_byte; ++j)
							last_byte |= (1 << j);
					if ((image->cache_map[map_len_bytes - 1] & last_byte) != last_byte)
						image->working = 0;
					else
						memlogf("[INFO] Instantly publishing relayed image '%s' because the local cache copy is complete", image_name);
				}
				close(fd);
			}

			/*
			 // 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
	return image;
error:
	// Free stuff. Some pointers might be zero, but calling free() on those is safe.
	free(image->cache_map);
	free(image->config_group);
	free(image->low_name);
	free(image->file);
	free(image->cache_file);
	g_free(image);
	return NULL;
}

/**
 * Iterate over all images and delete them if appropriate.
 */
void dnbd3_exec_delete(int save_if_changed)
{
	int changed = FALSE;
	const time_t now = time(NULL);
	GSList *image_iterator, *client_iterator;
	char ipstr[100];

	pthread_spin_lock(&_spinlock);
	for (image_iterator = _dnbd3_images; image_iterator; image_iterator = image_iterator->next)
	{
		dnbd3_image_t *image = image_iterator->data;
		int delete_now = TRUE;
		if (image->delete_hard != 0 && image->delete_hard < now)
		{
			// Drop all clients still using it
			for (client_iterator = _dnbd3_clients; client_iterator; client_iterator = client_iterator->next)
			{
				dnbd3_client_t *client = client_iterator->data;
				if (client->image != image)
					continue;
				// Kill client's connection
				*ipstr = '\0';
				inet_ntop(client->addrtype, client->ipaddr, ipstr, 100);
				memlogf("[INFO] delete_hard of %s reached; dropping client %s", image->config_group, ipstr);
				const int fd = client->sock;
				client->sock = -1;
				close(fd);
				delete_now = FALSE; // Wait for all clients being actually dropped; deletion will happen on next dnbd3_exec_delete()
			}
		} // END delete_hard image
		else if (image->delete_soft != 0 && image->delete_soft < now)
		{
			// Image should be soft-deleted
			// Check if it is still in use
			for (client_iterator = _dnbd3_clients; client_iterator; client_iterator = client_iterator->next)
			{
				const dnbd3_client_t *client = client_iterator->data;
				if (client->image == image)
				{	// Yep, still in use, keep it
					delete_now = FALSE;
					break;
				}
			}
		}
		else	// Neither hard nor soft delete, keep it
			delete_now = FALSE;
		if (delete_now)
		{
			// Image was not in use and should be deleted, free it!
			memlogf("[INFO] Freeing end-of-life image %s", image->config_group);
			changed = TRUE;
			_dnbd3_images = g_slist_remove(_dnbd3_images, image); // Remove from image list
			g_key_file_remove_group(_config_handle, image->config_group, NULL); // Also remove from config file
			// Free any allocated memory
			free(image->cache_map);
			free(image->config_group);
			free(image->low_name);
			free(image->file);
			free(image->cache_file);
			g_free(image);
			// Restart iteration as it would be messed up now
			image_iterator = _dnbd3_images;
		}
	} // END image iteration
	pthread_spin_lock(&_spinlock);

	if (changed && save_if_changed)
		save_config();
}

/**
 * Return local image name for a global image name
 * eg. "uni-freiburg/rz/ubuntu 12.04" -> "ubuntu 12.04"
 * ONLY IF the local name space really is "uni-freiburg/rz"
 * Returns NULL otherwise
 * The returned pointer points to memory inside the passed
 * string (if not NULL), so do not modify or free
 * / <---
static char* get_local_image_name(char *global_name)
{
	if (_local_namespace == NULL)
		return NULL; // No local namespace defined, so it cannot be local
	char *first_slash = strchr(global_name, '/');
	if (first_slash == NULL)
		return global_name; // Already local
	const size_t buflen = strlen(_local_namespace) + 1;
	if (first_slash - global_name + 1 != buflen)
		return NULL; // Namespaces have different length, cannot be same
	char namespace[buflen];
	char passedname[buflen];
	strcpy(namespace, _local_namespace);
	strncpy(passedname, global_name, buflen);
	passedname[buflen] = '\0';
	strtolower(namespace);
	strtolower(passedname);
	if (strcmp(namespace, passedname) == 0)
		return global_name + buflen; // points somewhere into passed buffer
	return NULL;
} //*/