/*
 * Copyright (c) 2015 Carsten Larsen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */


#include <stdio.h>
#include <string.h>
#include <math.h>

#include <exec/types.h>
#include <exec/io.h>
#include <exec/memory.h>
#include <proto/exec.h>
#include <clib/alib_protos.h>
#include <proto/dos.h>

#include <devices/timer.h>

#ifdef Debug
#undef Debug
#endif

#include "atimed.h"
#include "ntimed.h"

int amiga_get_time(struct timeval *tv);
int amiga_set_time(struct timeval *tv);
struct timerequest* create_timer();
void delete_timer(struct timerequest*);
void adjust_timeval(struct timeval *tv, double offset);

// Ntimed internals
static double adj_offset = 0;
static double adj_duration = 0;
static double adj_freq = 0;

static uintptr_t ticker;
static struct todolist *kt_tdl;

#ifndef AMIGA
struct timeval {
    ULONG tv_secs;
    ULONG tv_micro;
};
#endif

/**********************************************************************/

static void
amiga_setfreq(struct ocx *ocx, double frequency)
{
    assert(isfinite(frequency));

    // frequency offset (scaled ppm)
    long int freq = (long)floor(frequency * (65536 * 1e6));
    Put(ocx, OCX_TRACE, "KERNPLL %.6e\n", frequency);
}

static enum todo_e __match_proto__(todo_f)
amiga_ticker(struct ocx *ocx, struct todolist *tdl, void *priv)
{
    (void)ocx;
    AN(tdl);
    AZ(priv);
    amiga_setfreq(ocx, adj_freq);
    ticker = 0;
    return (TODO_OK);
}

static void __match_proto__(tb_adjust_f)
amiga_adjust(struct ocx *ocx, double offset, double duration, double frequency)
{
    double freq;

    (void)ocx;
    assert(duration >= 0.0);

    if (ticker)
        TODO_Cancel(kt_tdl, &ticker);

    adj_offset = offset;
    adj_duration = floor(duration);
    if (adj_offset > 0.0 && adj_duration == 0.0)
        adj_duration = 1.0;
    adj_freq = frequency;

    freq = adj_freq;
    if (adj_duration > 0.0)
        freq += adj_offset / adj_duration;
    amiga_setfreq(ocx, freq);
    if (adj_duration > 0.0)
        ticker = TODO_ScheduleRel(kt_tdl, amiga_ticker, NULL,
                                  adj_duration, 0.0, "KT_TICK");
}

/**********************************************************************/

static void __match_proto__(tb_step_f)
amiga_step(struct ocx *ocx, double offset)
{
    double d;
    struct timeval tv;

    Put(ocx, OCX_TRACE, "KERNTIME_STEP %.3e\n", offset);

    AZ(amiga_get_time(&tv));
    adjust_timeval(&tv, offset);
    AZ(amiga_set_time(&tv));
    TB_generation++;
}

/**********************************************************************/

static struct timestamp * __match_proto__(tb_now_f)
amiga_now(struct timestamp *storage)
{
    struct timeval tv;
    AZ(amiga_get_time(&tv));
    return (TS_Nanosec(storage, tv.tv_secs, tv.tv_micro * 1000LL));
}

/**********************************************************************/

static int __match_proto__(tb_sleep_f)
amiga_sleep(double dur)
{
    struct timeval tv;
    tv.tv_sec = 0;
    tv.tv_usec = 0;

    adjust_timeval(&tv, dur);

    struct timerequest *request = create_timer();
    if (request == NULL)
        return 1;

    request->tr_node.io_Command = TR_ADDREQUEST;
    request->tr_time = tv;

    DoIO((struct IORequest*)request);

    delete_timer(request);
    return 0;
}

/**********************************************************************/

void Time_Amiga(struct todolist *tdl)
{
    AN(tdl);
    TB_Step = amiga_step;
    TB_Adjust = amiga_adjust;
    TB_Sleep = amiga_sleep;
    TB_Now = amiga_now;
    kt_tdl = tdl;
}

void Time_Amiga_Passive(void)
{
    TB_Sleep = amiga_sleep;
    TB_Now = amiga_now;
}

/**********************************************************************/

struct timerequest* create_timer()
{
    struct MsgPort *port = CreatePort(0, 0);
    if (port == NULL)
        return NULL;

    struct timerequest *request = (struct timerequest*)CreateExtIO(port, sizeof(struct timerequest));
    if (request == NULL)
    {
        DeletePort(port);
        return NULL;
    }

    LONG error = OpenDevice(TIMERNAME, UNIT_MICROHZ, (struct IORequest*)request, 0L);
    if (error != 0)
    {
        delete_timer(request);
        return NULL;
    }

    return request;
}

void delete_timer(struct timerequest *request)
{
    if (request == NULL)
        return;

    struct MsgPort *port = request->tr_node.io_Message.mn_ReplyPort;

    if (port != 0)
        DeletePort(port);

    CloseDevice((struct IORequest*)request);
    DeleteExtIO((struct IORequest*)request);
}

/**********************************************************************/

// 2922 is the number of days between 1.1.1970 and 1.1.1978 (2 leap years and 6 normal)
const long amigaoffset = 2922 * 24 * 60 * 60; // 252460800
const long cetoffset = 60 * 60;

int amiga_get_time(struct timeval *tv)
{
    struct timerequest *request = create_timer();
    if (request == NULL)
        return 1;

    request->tr_node.io_Command = TR_GETSYSTIME;
    DoIO((struct IORequest*)request);

    *tv = request->tr_time;
    tv->tv_secs = tv->tv_secs + (amigaoffset - cetoffset);

    delete_timer(request);
    return 0;
}

int amiga_set_time(struct timeval *tv)
{
    struct timerequest *request = create_timer();
    if (request == NULL)
        return 1;

    request->tr_node.io_Command = TR_SETSYSTIME;
    request->tr_time = *tv;
    request->tr_time.tv_secs -= (amigaoffset - cetoffset);

    DoIO((struct IORequest*)request);

    delete_timer(request);
    return 0;
}

/**********************************************************************/

void adjust_timeval(struct timeval *tv, double offset)
{
    double d = floor(offset);
    offset -= d;

    long sec = tv->tv_secs + (long)d;
    long micro = tv->tv_micro + (long)floor(offset * 1e6);

    if (micro < 0) {
        sec -= 1;
        micro += 1000000;
    } else if (micro >= 1000000) {
        sec += 1;
        micro -= 1000000;
    }

    tv->tv_secs = sec;
    tv->tv_micro = micro;
}