/* 
 * Copyright 2010 Stefan Lankes, Chair for Operating Systems,
 *                               RWTH Aachen University
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * This file is part of MetalSVM.
 */

#include <metalsvm/stdarg.h>
#include <metalsvm/stdio.h>
#include <metalsvm/syscall.h>
#include <metalsvm/tasks.h>
#include <metalsvm/string.h>
#include <metalsvm/errno.h>
#include <metalsvm/spinlock.h>
#include <metalsvm/time.h>
#include <metalsvm/fs.h>
#include <lwip/opt.h>

#if defined(CONFIG_LWIP) && LWIP_SOCKET
#include <lwip/mem.h>
#include <lwip/raw.h>
#include <lwip/icmp.h>
#include <lwip/netif.h>
#include <lwip/sys.h>
#include <lwip/timers.h>
#include <lwip/inet_chksum.h>
#include <lwip/ip.h>
#include <lwip/sockets.h>
#include <lwip/inet.h>
#include <lwip/err.h>

#endif

static int get_fildes(void)
{
	task_t* curr_task = per_core(current_task);
	int fd; 

	/* 
	 * Seach the process specific file descriptor table for a free 
	 * descriptor. The new descriptor returned by the call is the lowest
     	 * numbered descriptor currently not in use by the process. 
	 */
	for (fd = 0; fd < NR_OPEN; fd++) {
		if (curr_task->fildes_table[fd] == NULL) {
			/* Init Filedescriptor */
			curr_task->fildes_table[fd] = kmalloc(sizeof(fildes_t));
			memset(curr_task->fildes_table[fd], 0x00, sizeof(fildes_t));
			return fd;
		} 
 	}

	/* can't get any free fd */
	return -EMFILE;
}

static int sys_write(int fd, const char* buf, size_t len)
{
	task_t* curr_task = per_core(current_task);

	/* fd is negative or greater than the maximum allowable number */ 
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return -EBADF;
	/* fd is not an active, valid file descriptor. */
	if (curr_task->fildes_table[fd] == NULL)
		return -EBADF;

	return write_fs(curr_task->fildes_table[fd], (uint8_t*)buf, len);
}

static int sys_open(const char* name, int flags, int mode)
{
	int fd, check;
	task_t* curr_task = per_core(current_task);

	/* no name is given */
	if (name == NULL)
		return -EINVAL;

	/* Get a free file descriptor */
	fd = get_fildes();

	/* fd is negative or greater than the maximum allowable number */ 
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return fd; /* in this case fd = errno */

	/* init the whole file descriptor structure */
	curr_task->fildes_table[fd]->mode = mode;
	curr_task->fildes_table[fd]->flags = flags;
	curr_task->fildes_table[fd]->count = 1;
	check = open_fs(curr_task->fildes_table[fd], (char*) name);

	/* file doesn't exist! */
	if (check < 0) {
		/* tidy up the fildescriptor */
		kfree(curr_task->fildes_table[fd]);
		curr_task->fildes_table[fd] = NULL;
		return check;
 	}

	return fd;
}

static int sys_stat(const char* name, struct stat* st) 
{
	vfs_node_t* node;

	node = findnode_fs(name);
	if (node == NULL)
		return -EINVAL;

	st->st_dev = 0; 		/* ID of device containing file */
	st->st_ino = 0;			/* inode number */

	/* convert FS_TYPES in newlib FS_TYPES */
	switch (node->type)
	{
		case FS_FILE:		st->st_mode = 0060000; break;
		case FS_DIRECTORY: 	st->st_mode = 0040000; break;
		case FS_CHARDEVICE:	st->st_mode = 0020000; break;
		default:		st->st_mode = 0; break;
	}

	st->st_nlink = 0;		/* number of hard links */
	st->st_uid = node->uid;		/* user ID of owner */
	st->st_gid = node->gid;		/* group ID of owner */
	st->st_rdev = node->type;	/* device ID (if special file) */
	st->st_size = (node->block_size / MAX_DATAENTRIES + 1) * MAX_DATAENTRIES;	/* total size, in bytes */
	st->st_blksize = node->block_size;	/* blocksize for filesystem I/O */
	st->st_blocks = node->block_size / MAX_DATAENTRIES + 1;		/* number of blocks allocated */
	st->st_atim.tv_sec = 0;		/* time of last access */
	st->st_atim.tv_nsec = 0;
	st->st_mtim.tv_sec = 0;		/* time of last modification */
	st->st_mtim.tv_nsec = 0;
	st->st_ctim.tv_sec = 0;		/* time of last status change */
	st->st_ctim.tv_nsec = 0;

	return 0;
}

static int sys_read(int fd, const char* buf, size_t len)
{
	task_t* curr_task = per_core(current_task);

	/* fd is negative or greater than the maximum allowable number */ 
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return -EBADF;
	/* fd is not an active, valid file descriptor. */
	if (curr_task->fildes_table[fd] == NULL)
		return -EBADF;

	return read_fs(curr_task->fildes_table[fd], (uint8_t*)buf, len);
}

#if defined(CONFIG_LWIP) && LWIP_SOCKET
static int sys_socket(int domain, int type, int protocol)
{
	int fd, sock;
	task_t* curr_task = per_core(current_task);

	/* Get a free file descriptor */
	fd = get_fildes();

	/* validate the file descriptor */
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return fd; /* in this case fd = errno */

	/* Get a valid lwip descriptor */
	sock = lwip_socket(domain, type, protocol);

	/* validate the file descriptor */
	if (BUILTIN_EXPECT(sock < 0, 0))
		return sock; /* in this case sock = errno */

	/* 
	 * init the whole file descriptor structure.
	 * We use the offset to save the lwip descriptor
	 * TODO: find another solution or change the name 'offset'
	 */
	curr_task->fildes_table[fd]->offset = sock;
	curr_task->fildes_table[fd]->count = 1;
	curr_task->fildes_table[fd]->node = findnode_fs("/dev/socket"); 

	/* file doesn't exist! */
	if (curr_task->fildes_table[fd]->node == NULL) {
		/* tidy up the fildescriptor */
		kfree(curr_task->fildes_table[fd]);
		curr_task->fildes_table[fd] = NULL;
		return -ENOENT;
 	}

	return fd;
}

static int sys_accept(int s, struct sockaddr* addr, socklen_t* addrlen)
{
	int fd, sock2;
	task_t* curr_task = per_core(current_task);

	/* validate the 'socket'-filedescriptor */
	if (BUILTIN_EXPECT((s >= NR_OPEN) || (s < 0), 0))
		return -EBADF;
	/* validate the 'socket'-file descriptor object */
	if (curr_task->fildes_table[s] == NULL)
		return -EBADF;

	/* Get a free file descriptor */
	fd = get_fildes();

	/* validate the file descriptor */
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return fd; /* in this case fd = errno */
	/* Get a valid lwip descriptor */
	sock2 = lwip_accept(s, addr, addrlen);
	/* validate the file descriptor */
	if (BUILTIN_EXPECT(sock2 < 0, 0))
		return sock2; /* in this case sock = errno */

	/* 
	 * init the whole file descriptor structure.
	 * We use the offset to save the lwip descriptor
	 * TODO: find another solution or change the name 'offset'
	 */
	curr_task->fildes_table[fd]->offset = sock2;
	curr_task->fildes_table[fd]->count = 1;
	curr_task->fildes_table[fd]->node = findnode_fs("/dev/socket");
	
	/* file doesn't exist! */
	if (curr_task->fildes_table[fd]->node == NULL) {
		/* tidy up the fildescriptor */
		kfree(curr_task->fildes_table[fd]);
		curr_task->fildes_table[fd] = NULL;
		return -ENOENT;
 	}

	return fd;
}

#endif


static int sys_close(int fd)
{
	int check;
	task_t* curr_task = per_core(current_task);

	/* fd is negative or greater than the maximum allowable number */ 
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return -EBADF;
	/* fd is not an active, valid file descriptor. */
	if (curr_task->fildes_table[fd] == NULL)
		return -EBADF;

	/*
	 * The close() call deletes a descriptor from the per-process object 
	 * reference table.  If this is the last reference to the underlying 
	 * object, the object will be deactivated. 
	 */
	if (curr_task->fildes_table[fd]->count == 1) {
		check = close_fs(curr_task->fildes_table[fd]);
		/* close command failed -> return check = errno */
		if (BUILTIN_EXPECT(check < 0, 0))
			return check; 
		kfree(curr_task->fildes_table[fd]);
		curr_task->fildes_table[fd] = NULL;
	} else {
		curr_task->fildes_table[fd]->count--;
		curr_task->fildes_table[fd] = NULL;
	}

	return 0;

}
 
static int sys_lseek(int fd, off_t pos, int origin)
{
	int ret = -EINVAL;
	task_t* curr_task = per_core(current_task);

	/* fd is negative or greater than the maximum allowable number */ 
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return -EBADF;
	/* fd is not an active, valid file descriptor. */
	if (curr_task->fildes_table[fd] == NULL)
		return -EBADF;

	/* TODO: in case of Fildes is associated with a pipe, socket, or FIFO. return ESPIPE */
	/* TODO: The seek location is too large to be stored in an object of type off_t. return EOVERFLOW*/

	switch(origin) 
	{
	case SEEK_SET: {	/* set file offset to offset */
			ret = pos;
			/* The seek location is negative. */
			if (ret < 0) 
				return -EINVAL;
			curr_task->fildes_table[fd]->offset = ret;
			ret = 0;
			break;
		}
	case SEEK_CUR: {	/* set file offset to current plus offset */
			ret = pos + curr_task->fildes_table[fd]->offset;
			/* The seek location is negative. */
			if (ret < 0) 
				return -EINVAL;
			break;
		}
	case SEEK_END: {	/* set file offset to EOF plus offset */
			ret = pos + curr_task->fildes_table[fd]->node->block_size;
			/* The seek location is negative. */
			if (ret < 0) 
				return -EINVAL;
			curr_task->fildes_table[fd]->offset = ret;
			ret = 0;
			break;
		}
	default:
		ret = -EINVAL;
		break;
	}

	return ret;
}

static int sys_dup(int fd)
{
	task_t* curr_task = per_core(current_task);
	int new_fd;

	/* fd is negative or greater than the maximum allowable number */ 
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return -EBADF;
	/* fd is not an active, valid file descriptor. */
	if (curr_task->fildes_table[fd] == NULL)
		return -EBADF;

	/* Get a free file descriptor */
	new_fd = get_fildes();
	/* validate the file descriptor */
	if (BUILTIN_EXPECT((new_fd >= NR_OPEN) || (fd < 0), 0))
		return new_fd; /* in this case fd = errno */

	/* 
	 * free the memory which was allocated in get_fildes() 
	 * cause will link it to another existing memory space
	 */
	kfree(curr_task->fildes_table[new_fd]);

	/* and link it to another existing memory space */
	curr_task->fildes_table[new_fd] = curr_task->fildes_table[fd];
	curr_task->fildes_table[fd]->count++;

	return new_fd;
}

static int sys_dup2(int fd, int fd2)
{
	task_t* curr_task = per_core(current_task);

	/* fd and fd2 is negative or greater than the maximum allowable number */ 
	if (BUILTIN_EXPECT((fd >= NR_OPEN) || (fd < 0), 0))
		return -EBADF;
	if (BUILTIN_EXPECT((fd2 >= NR_OPEN) || (fd2 < 0), 0))
		return -EBADF;
	/* fd is not an active, valid file descriptor. */
	if (curr_task->fildes_table[fd] == NULL)
		return -EBADF;

	/* If fd and fd2 are equal, then dup2() just returns fd2 */
	if (fd == fd2)
		return fd2;
	
	/*
	 * if descriptor fd2 is already in use, it is first deallocated 
	 * as if a close(2) call had been done first
	 */
	if (curr_task->fildes_table[fd2] != NULL)
		sys_close(fd2);

	curr_task->fildes_table[fd2] = curr_task->fildes_table[fd];
	curr_task->fildes_table[fd]->count++;

	return fd2;
}

static int sys_sbrk(int incr)
{
	task_t* task = per_core(current_task);
	vma_t* tmp = NULL;
	int ret;

	spinlock_lock(&task->vma_lock);

	// search vma containing the heap
	tmp = task->vma_list;
        while(tmp && !((task->end_heap >= tmp->start) && (task->end_heap <= tmp->end)))
		tmp = tmp->next;

	ret = (int) task->end_heap;
	task->end_heap += incr;
	if (task->end_heap < task->start_heap)
		task->end_heap = task->start_heap;

	// resize virtual memory area
	if (tmp && (tmp->end <= task->end_heap))
		tmp->end = task->end_heap;

	// allocation and mapping of new pages for the heap
	// is catched by the pagefault handler

	//kprintf("sys_sbrk: tid=%d, start_heap=%8x, end_heap=%8x, incr=%4x\n", task->id, task->start_heap, task->end_heap, incr);

	spinlock_unlock(&task->vma_lock);

	return ret;
}

int syscall_handler(uint32_t sys_nr, ...)
{
	int ret = -EINVAL;
	va_list vl;

	check_workqueues();

	va_start(vl, sys_nr);

	switch(sys_nr) 
	{
	case __NR_exit:
		sys_exit(va_arg(vl, uint32_t));
		ret = 0;
		break;
	case __NR_write: {
			int fd = va_arg(vl, int);
			const char* buf = va_arg(vl, const char*);
			size_t len = va_arg(vl, size_t);
			ret = sys_write(fd, buf, len);
			break;
		}
	case __NR_open: {
			const char* name = va_arg(vl, const char*);
			int flags = va_arg(vl, int);
			int mode = va_arg(vl, int);
			ret = sys_open(name, flags, mode);
			break;
		}
	case __NR_close: {
			int fd = va_arg(vl, int);
			ret = sys_close(fd);
			break;
 		}
	case __NR_dup: {
			int fd = va_arg(vl, int);
			ret = sys_dup(fd);
			break;
		}
	case __NR_dup2: {
			int fd = va_arg(vl, int);
			int fd2 = va_arg(vl, int);
			ret = sys_dup2(fd, fd2);
			break;
		}
	case __NR_stat: {
			const char* name = va_arg(vl, const char*);
			struct stat* st = va_arg(vl, struct stat*);
			ret = sys_stat(name, st);
			break;
		}
	case __NR_read: {
			int fd = va_arg(vl, int);
			const char* buf = va_arg(vl, const char*);
 			size_t len = va_arg(vl, size_t);
			ret = sys_read(fd, buf, len);
			break;
		}
	case __NR_lseek: {
			int fd = va_arg(vl, int);
			off_t pos = va_arg(vl, off_t);
 			int origin = va_arg(vl, int);
			ret = sys_lseek(fd, pos, origin);
			break;
		}
	case __NR_sbrk: {
			int incr = va_arg(vl, int);

			ret = sys_sbrk(incr);
			break;
		}
	case __NR_getpid:
		ret = per_core(current_task)->id;
		break;
	case __NR_fork:
		ret = sys_fork();
		break;
	case __NR_wait: {
			int32_t* status = va_arg(vl, int32_t*);
	
			ret = wait(status);
			break;
		}
	case __NR_execve: {
			const char* name = va_arg(vl, const char*);
			char** argv = va_arg(vl, char**);
			char** env = va_arg(vl, char**);

			ret = sys_execve(name, argv, env);
			break;
		}
	case __NR_times: {
			struct tms* buffer = va_arg(vl, struct tms*);
			clock_t* clock = va_arg(vl, clock_t*);

			ret = sys_times(buffer, clock);
			break;
		}
#if defined(CONFIG_LWIP) && LWIP_SOCKET
	case __NR_closesocket: {
		int fd = va_arg(vl, int);

		if (fd < 0) {
			ret = -ENOTSOCK;
			break;
		}
		ret = lwip_close(per_core(current_task)->fildes_table[fd]->offset);
		if (ret < 0)
			ret = -errno;
		break;
	}
	case __NR_socket: {
		int domain = va_arg(vl, int);
		int type = va_arg(vl, int);
		int protocol = va_arg(vl, int);

		ret = sys_socket(domain, type, protocol);
		break;
	}
	case __NR_connect: {
		int fd = va_arg(vl, int);
		const struct sockaddr* name = va_arg(vl, const struct sockaddr*);
		socklen_t namelen = va_arg(vl, socklen_t);

		if (per_core(current_task)->fildes_table[fd]->offset < 0) {
			ret = -ENOTSOCK;
			break;
		}
		//kprintf("lwip_connect: %p with lenght %i and Socket %i", name, namelen, per_core(current_task)->fildes_table[fd].offset);


		ret = lwip_connect(per_core(current_task)->fildes_table[fd]->offset, name, namelen);
		if (ret < 0)
			ret = -errno;
		break;
	}
	case __NR_bind: {
		int fd = va_arg(vl, int);
		const struct sockaddr* name = va_arg(vl, const struct sockaddr*);
		socklen_t namelen = va_arg(vl, socklen_t);

		if (per_core(current_task)->fildes_table[fd]->offset < 0) {
			ret = -ENOTSOCK;
			break;
		}
		ret = lwip_bind(per_core(current_task)->fildes_table[fd]->offset, name, namelen);
		if (ret < 0)
			ret = -errno;
		break;
	}
	case __NR_listen: {
		int fd = va_arg(vl, int);
		int backlog = va_arg(vl, int);

		if (per_core(current_task)->fildes_table[fd]->offset < 0) {
			ret = -ENOTSOCK;
			break;
		}

		ret = lwip_listen(per_core(current_task)->fildes_table[fd]->offset, backlog);
		if (ret < 0)
			ret = -errno;
		break;
	}
	case __NR_accept: {
		int fd = va_arg(vl, int);
		struct sockaddr* addr = va_arg(vl, struct sockaddr*);
		socklen_t* addrlen = va_arg(vl, socklen_t*);

		if (per_core(current_task)->fildes_table[fd]->offset < 0) {
			ret = -ENOTSOCK;
			break;
		}
		ret = sys_accept(per_core(current_task)->fildes_table[fd]->offset, addr, addrlen);
		if (ret < 0)
			ret = -errno;
		break;
	}
#endif
	default:
		kputs("invalid system call\n");
		ret = -ENOSYS;
		break;
	};

	va_end(vl);

	return ret;
}