/* $Id$ */

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file thread_morphos.cpp MorphOS implementation of Threads. */

#include "../stdafx.h"
#include "thread.h"
#include "../debug.h"
#include "../core/alloc_func.hpp"
#include <stdlib.h>
#include <unistd.h>

#include <exec/types.h>
#include <exec/rawfmt.h>
#include <dos/dostags.h>

#include <proto/dos.h>
#include <proto/exec.h>

#include "../safeguards.h"

/**
 *  avoid name clashes with MorphOS API functions
 */
#undef Exit
#undef Wait


/**
 *  NOTE: this code heavily depends on latest libnix updates. So make
 *        sure you link with new stuff which supports semaphore locking of
 *        the IO resources, else it will just go foobar.
 */


struct OTTDThreadStartupMessage {
	struct Message msg;  ///< standard exec.library message (MUST be the first thing in the message struct!)
	OTTDThreadFunc func; ///< function the thread will execute
	void *arg;           ///< functions arguments for the thread function
};


/**
 *  Default OpenTTD STDIO/ERR debug output is not very useful for this, so we
 *  utilize serial/ramdebug instead.
 */
void KPutStr(CONST_STRPTR format)
{
	RawDoFmt(format, NULL, (void (*)())RAWFMTFUNC_SERIAL, NULL);
}


/**
 * MorphOS version for ThreadObject.
 */
class ThreadObject_MorphOS : public ThreadObject {
private:
	APTR m_thr;                  ///< System thread identifier.
	struct MsgPort *m_replyport;
	struct OTTDThreadStartupMessage m_msg;
	bool self_destruct;

public:
	/**
	 * Create a sub process and start it, calling proc(param).
	 */
	ThreadObject_MorphOS(OTTDThreadFunc proc, void *param, self_destruct) :
		m_thr(0), self_destruct(self_destruct)
	{
		struct Task *parent;

		KPutStr("[OpenTTD] Create thread...\n");

		parent = FindTask(NULL);

		/* Make sure main thread runs with sane priority */
		SetTaskPri(parent, 0);

		/* Things we'll pass down to the child by utilizing NP_StartupMsg */
		m_msg.func = proc;
		m_msg.arg  = param;

		m_replyport = CreateMsgPort();

		if (m_replyport != NULL) {
			struct Process *child;

			m_msg.msg.mn_Node.ln_Type = NT_MESSAGE;
			m_msg.msg.mn_ReplyPort    = m_replyport;
			m_msg.msg.mn_Length       = sizeof(struct OTTDThreadStartupMessage);

			child = CreateNewProcTags(
				NP_CodeType,     CODETYPE_PPC,
				NP_Entry,        ThreadObject_MorphOS::Proxy,
				NP_StartupMsg,   (IPTR)&m_msg,
				NP_Priority,     5UL,
				NP_Name,         (IPTR)"OpenTTD Thread",
				NP_PPCStackSize, 131072UL,
				TAG_DONE);

			m_thr = (APTR) child;

			if (child != NULL) {
				KPutStr("[OpenTTD] Child process launched.\n");
			} else {
				KPutStr("[OpenTTD] Couldn't create child process. (constructors never fail, yeah!)\n");
				DeleteMsgPort(m_replyport);
			}
		}
	}

	/* virtual */ ~ThreadObject_MorphOS()
	{
	}

	/* virtual */ bool Exit()
	{
		struct OTTDThreadStartupMessage *msg;

		/* You can only exit yourself */
		assert(IsCurrent());

		KPutStr("[Child] Aborting...\n");

		if (NewGetTaskAttrs(NULL, &msg, sizeof(struct OTTDThreadStartupMessage *), TASKINFOTYPE_STARTUPMSG, TAG_DONE) && msg != NULL) {
			/* For now we terminate by throwing an error, gives much cleaner cleanup */
			throw OTTDThreadExitSignal();
		}

		return true;
	}

	/* virtual */ void Join()
	{
		struct OTTDThreadStartupMessage *reply;

		/* You cannot join yourself */
		assert(!IsCurrent());

		KPutStr("[OpenTTD] Join threads...\n");
		KPutStr("[OpenTTD] Wait for child to quit...\n");
		WaitPort(m_replyport);

		GetMsg(m_replyport);
		DeleteMsgPort(m_replyport);
		m_thr = 0;
	}

	/* virtual */ bool IsCurrent()
	{
		return FindTask(NULL) == m_thr;
	}

private:
	/**
	 * On thread creation, this function is called, which calls the real startup
	 *  function. This to get back into the correct instance again.
	 */
	static void Proxy()
	{
		struct Task *child = FindTask(NULL);
		struct OTTDThreadStartupMessage *msg;

		/* Make sure, we don't block the parent. */
		SetTaskPri(child, -5);

		KPutStr("[Child] Progressing...\n");

		if (NewGetTaskAttrs(NULL, &msg, sizeof(struct OTTDThreadStartupMessage *), TASKINFOTYPE_STARTUPMSG, TAG_DONE) && msg != NULL) {
			try {
				msg->func(msg->arg);
			} catch(OTTDThreadExitSignal e) {
				KPutStr("[Child] Returned to main()\n");
			} catch(...) {
				NOT_REACHED();
			}
		}

		/*  Quit the child, exec.library will reply the startup msg internally. */
		KPutStr("[Child] Done.\n");

		if (self_destruct) delete this;
	}
};

/* static */ bool ThreadObject::New(OTTDThreadFunc proc, void *param, ThreadObject **thread, const char *name)
{
	ThreadObject *to = new ThreadObject_MorphOS(proc, param, thread == NULL);
	if (thread != NULL) *thread = to;
	return true;
}