#include <stdlib.h>

#include "cryptoki-capi.h"

typedef struct _SessionList {
	Session **list;
	size_t lmax;
} SessionList;

/* These are protected by global_mutex */
static SessionList the_sessions = { NULL, 0 };


Session*
ckcapi_session_create(void)
{
	Session* sess = calloc(1, sizeof(Session));
	if(!sess)
		return NULL;

	sess->mutex = CreateMutex(NULL, FALSE, NULL);
	if(!sess->mutex) 
	{
		free(sess);
		return NULL;
	}

	DBGS(sess, "created");
	return sess;
}

CK_RV 
ckcapi_session_register(Session* sess)
{
	CK_ULONG id = 0;
	CK_RV ret = CKR_OK;
	size_t i;

	ASSERT(sess);
	ASSERT(sess->id == 0 && sess->refs == 0);

	DBGS(sess, "registering new session");

	ckcapi_lock_global();

		/* Find a nice session identifier */
		while(id == 0) {

			/* 
			 * PKCS#11 GRAY AREA: We're assuming we can reuse session
			 * handles. PKCS#11 spec says they're like file handles,
			 * and file handles get reused :)
			 */
			
			/* Note we never put anything in array position '0' */
			for(i = 1; i < the_sessions.lmax; ++i) 
			{
				/* Any empty position will do */
				if(!the_sessions.list[i]) 
				{
					id = i;
					break;
				}
			}

			/* Couldn't find a handle, reallocate */
			if(id == 0) 
			{
				Session** buf;
				size_t oldmax, newmax;

				oldmax = the_sessions.lmax;
				newmax = oldmax + 16;

				buf = realloc(the_sessions.list, newmax * sizeof(Session*));
				if(!buf)
				{
					DBGS(sess, ("couldn't allocate session list, out of memory"));
					ret = CKR_HOST_MEMORY;
					break;
				}

				/* Choose the first of the new block as the id */
				id = oldmax;

				/* Clear new memory */
				the_sessions.list = buf;
				for( ; oldmax < newmax; ++oldmax)
					buf[oldmax] = NULL;
				the_sessions.lmax = newmax;

				DBG(("allocated new session list: %d max", newmax));	
			}
		}

		if(ret == CKR_OK) 
		{
			ASSERT(id > 0 && id < the_sessions.lmax);
			ASSERT(the_sessions.list[id] == NULL);

			/* And assign it to the session handle */
			the_sessions.list[id] = sess;
			sess->id = id;
			
			/* The session list reference */
			ASSERT(sess->refs == 0);
			sess->refs++;
			
			DBGS(sess, "registered sesson id");
		}

	ckcapi_unlock_global();

	return ret;
}

void
ckcapi_session_destroy(Session* sess)
{
	ASSERT(sess);
	ASSERT(sess->refs == 0);

	/* Ask any pending operations to cleanup */
	if(sess->operation_type)
	{
		ASSERT(sess->operation_cancel);
		(sess->operation_cancel)(sess);
	}

	ASSERT(sess->operation_type == 0);
	ASSERT(sess->operation_data == NULL);
	ASSERT(sess->operation_cancel == NULL);

	/* And make the mutex go away */
	ASSERT(sess->mutex != NULL);
	CloseHandle(sess->mutex);
	
	DBGS(sess, "destroyed");
	free(sess);
}

static CK_RV 
find_lock_ref_internal(SessionList* sessions, CK_SESSION_HANDLE id, 
					   int remove, Session** sess_ret)
{
	Session *sess;
	DWORD r;
	
	ASSERT(sessions);
	ASSERT(sess_ret);
	
	if(id >= sessions->lmax) 
	{
		DBG(("invalid session id: %d", id));
		return CKR_SESSION_HANDLE_INVALID;
	}

	/* A seemingly valid id */
	ASSERT(sessions->list);
	sess = sessions->list[id]; 
	
	if(!sess) 
	{
		DBG(("session does not exist: %d", id));
		return CKR_SESSION_HANDLE_INVALID;
	}

	ASSERT(sess->id == id);
	
	/* Closing takes precedence over active operations */
	if(!remove) 
	{
		/* 
		 * An initial check is done to make sure this session is not active. 
		 * This is done outside of the lock. The real check is done later 
		 * inside a lock. This is so we can return quickly without blocking
		 * in most cases. 
		 */
	
		if(sess->in_call) 
		{
			DBGS(sess, ("an operation is already active in this session"));
			return CKR_OPERATION_ACTIVE;
		}
	}

	/* Lock the CallSession */
	r = WaitForSingleObject(sess->mutex, INFINITE);
	ASSERT(r == WAIT_OBJECT_0);

	/* Do the real check */
	if(!remove && sess->in_call) 
	{
		ReleaseMutex(sess->mutex);
		DBGS(sess, ("an operation is already active in this session"));
		return CKR_OPERATION_ACTIVE;
	}

	/* Make sure it doesn't go away */
	ASSERT(sess->refs > 0);
	sess->refs++;

	DBGS(sess, "found and locked session");
	
	/* And remove it if necessary */
	if(remove) 
	{
		sessions->list[id] = NULL;
		
		/* The session list reference */
		sess->refs--;
		ASSERT(sess->refs > 0);
		
		DBGS(sess, "removed session from list");
	}
	else
	{
		ASSERT(!sess->in_call);
		sess->in_call = 1;
	}
	
	*sess_ret = sess;
	return CKR_OK;
}

CK_RV
ckcapi_session_find_lock_ref(CK_ULONG id, int remove, Session **sess)
{
	/* This must be called without any locks held */

	CK_RV ret = CKR_OK;

	ASSERT(sess);
	
	if(id <= 0)
	{
		DBG(("invalid session id passed: %d", id));
		return CKR_ARGUMENTS_BAD;
	}
	
	ckcapi_lock_global();
	
		ret = find_lock_ref_internal (&the_sessions, id, remove, sess);

	ckcapi_unlock_global();
	
	return ret;
}

void
ckcapi_session_unref_unlock(Session* sess)
{
	/* The CallSession must be locked at this point */

	int refs;
	BOOL r;
	
	ASSERT(sess);
	
	ASSERT(sess->refs > 0);
	sess->refs--;
	refs = sess->refs;

	sess->in_call = 0;

	DBGS(sess, "unlocked session");

	r = ReleaseMutex(sess->mutex);
	ASSERT(r == TRUE);
	
	/* 
	 * At this point if no references are held, then we can safely 
	 * delete. No other thread should be involved. 
	 */
	
	if(refs == 0)
		ckcapi_session_destroy(sess);
}

void 
ckcapi_session_close_all()
{
	/* This must be called without any locks held */
	
	SessionList sessions;
	Session *sess;
	size_t i;
	CK_RV ret;

	/* 
	 * PKCS#11 GRAY AREA: What happens when this gets called 
	 * concurrently? We don't return an error on the second call,
	 * because by the time it returns, all sessions should be closed.
	 */

	ckcapi_lock_global();

		/* Steal all the session data */
		sessions.list = the_sessions.list;
		the_sessions.list = NULL;
		sessions.lmax = the_sessions.lmax;
		the_sessions.lmax = 0;
		
		if(sessions.list || sessions.lmax) 
			DBG(("closing all sessions"));

	ckcapi_unlock_global();

	/* Close each session in turn */
	for(i = 1; i < sessions.lmax; ++i) 
	{
		if(!sessions.list[i])
			continue;
		
		ret = find_lock_ref_internal (&sessions, i, 1, &sess);
		ASSERT(ret == CKR_OK);

		ckcapi_session_unref_unlock(sess);
	}

	/* We stole the memory above, free it now */
	if(sessions.list) 
	{
		free(sessions.list);
		DBG(("freed session list"));
	}
}