/*
 * Copyright (c) 2022 Barcelona Supercomputing Center (BSC)
 *
 * This program 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "uthash.h"
#include "utlist.h"

#include "ovni.h"
#include "emu.h"
#include "emu_task.h"
#include "prv.h"
#include "chan.h"

void
hook_init_nanos6(struct ovni_emu *emu)
{
	struct ovni_ethread *th;
	struct ovni_cpu *cpu;
	struct ovni_chan **uth, **ucpu;
	int row;
	FILE *prv_th, *prv_cpu;
	int64_t *clock;

	clock = &emu->delta_time;
	prv_th = emu->prv_thread;
	prv_cpu = emu->prv_cpu;

	/* Init the channels in all threads */
	for(size_t i=0; i<emu->total_nthreads; i++)
	{
		th = emu->global_thread[i];
		row = th->gindex + 1;

		uth = &emu->th_chan;

		chan_th_init(th, uth, CHAN_NANOS6_TASKID,    CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_th, clock);
		chan_th_init(th, uth, CHAN_NANOS6_TYPE,      CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_th, clock);
		chan_th_init(th, uth, CHAN_NANOS6_SUBSYSTEM, CHAN_TRACK_TH_ACTIVE,  0, 0, 1, row, prv_th, clock);
		chan_th_init(th, uth, CHAN_NANOS6_RANK,      CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_th, clock);
		chan_th_init(th, uth, CHAN_NANOS6_THREAD,    CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_th, clock);
	}

	/* Init the Nanos6 channels in all cpus */
	for(size_t i=0; i<emu->total_ncpus; i++)
	{
		cpu = emu->global_cpu[i];
		row = cpu->gindex + 1;
		ucpu = &emu->cpu_chan;

		chan_cpu_init(cpu, ucpu, CHAN_NANOS6_TASKID,    CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_cpu, clock);
		chan_cpu_init(cpu, ucpu, CHAN_NANOS6_TYPE,      CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_cpu, clock);
		chan_cpu_init(cpu, ucpu, CHAN_NANOS6_SUBSYSTEM, CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_cpu, clock);
		chan_cpu_init(cpu, ucpu, CHAN_NANOS6_RANK,      CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_cpu, clock);
		chan_cpu_init(cpu, ucpu, CHAN_NANOS6_THREAD,    CHAN_TRACK_TH_RUNNING, 0, 0, 1, row, prv_cpu, clock);
	}

	/* Init task stack */
	for(size_t i=0; i<emu->total_nthreads; i++)
	{
		th = emu->global_thread[i];
		th->nanos6_task_stack.thread = th;
	}
}

/* --------------------------- pre ------------------------------- */

static void
chan_task_stopped(struct ovni_emu *emu, char tr)
{
	struct ovni_ethread *th;
	th = emu->cur_thread;

	chan_set(&th->chan[CHAN_NANOS6_TASKID], 0);
	chan_set(&th->chan[CHAN_NANOS6_TYPE], 0);

	if(emu->cur_loom->rank_enabled)
		chan_set(&th->chan[CHAN_NANOS6_RANK], 0);

    /* Only exit the task body when finishing */
    if(tr == 'e')
        chan_pop(&th->chan[CHAN_NANOS6_SUBSYSTEM], ST_NANOS6_TASK_BODY);
}

static void
chan_task_running(struct ovni_emu *emu, struct task *task, char tr)
{
	struct ovni_ethread *th;
	struct ovni_eproc *proc;

	th = emu->cur_thread;
	proc = emu->cur_proc;

	if(task->id == 0)
		die("task id cannot be 0\n");

	if(task->type->gid == 0)
		die("task type gid cannot be 0\n");

	if(proc->appid <= 0)
		die("app id must be positive\n");

	chan_set(&th->chan[CHAN_NANOS6_TASKID], task->id);
	chan_set(&th->chan[CHAN_NANOS6_TYPE], task->type->gid);

	if(emu->cur_loom->rank_enabled)
		chan_set(&th->chan[CHAN_NANOS6_RANK], proc->rank + 1);

    /* Only enter the body of the task when we begin the execution */
    if(tr == 'x')
        chan_push(&th->chan[CHAN_NANOS6_SUBSYSTEM], ST_NANOS6_TASK_BODY);
}

static void
chan_task_switch(struct ovni_emu *emu,
		struct task *prev, struct task *next)
{
	struct ovni_ethread *th = emu->cur_thread;

	if(!prev || !next)
		die("cannot switch to or from a NULL task\n");

	if(prev == next)
		die("cannot switch to the same task\n");

	if(next->id == 0)
		die("next task id cannot be 0\n");

	if(next->type->gid == 0)
		die("next task type id cannot be 0\n");

	if(prev->thread != next->thread)
		die("cannot switch to a task of another thread\n");

	/* No need to change the rank as we will switch to tasks from
	 * same thread */
	chan_set(&th->chan[CHAN_NANOS6_TASKID], next->id);

	/* FIXME: We should emit a PRV event even if we are switching to
	 * the same type event, to mark the end of the current task. For
	 * now we only emit a new type if we switch to a type with a
	 * different gid. */
	if(prev->type->gid != next->type->gid)
		chan_set(&th->chan[CHAN_NANOS6_TYPE], next->type->gid);
}

static void
update_task_state(struct ovni_emu *emu)
{
	if(ovni_payload_size(emu->cur_ev) < 4)
		die("missing task id in payload\n");

	uint32_t task_id = emu->cur_ev->payload.u32[0];

	struct ovni_ethread *th = emu->cur_thread;
	struct ovni_eproc *proc = emu->cur_proc;

	struct task_info *info = &proc->nanos6_task_info;
	struct task_stack *stack = &th->nanos6_task_stack;

	struct task *task = task_find(info->tasks, task_id);

	if(task == NULL)
		die("cannot find task with id %u\n", task_id);

	switch(emu->cur_ev->header.value)
	{
		case 'x': task_execute(stack, task); break;
		case 'e': task_end(stack, task); break;
		case 'p': task_pause(stack, task); break;
		case 'r': task_resume(stack, task); break;
		default:
			  die("unexpected Nanos6 task event value %c\n",
					  emu->cur_ev->header.value);
	}
}

static char
expand_transition_value(struct ovni_emu *emu, int was_running, int runs_now)
{
	char tr = emu->cur_ev->header.value;

	/* Ensure we don't clobber the value */
	if(tr == 'X' || tr == 'E')
		die("unexpected event value %c\n", tr);

	/* Modify the event value to detect nested transitions */
	if(tr == 'x' && was_running)
		tr = 'X'; /* Execute a new nested task */
	else if(tr == 'e' && runs_now)
		tr = 'E'; /* End a nested task */

	return tr;
}

static void
update_task_channels(struct ovni_emu *emu,
		char tr, struct task *prev, struct task *next)
{
	switch(tr)
	{
		case 'x':
		case 'r':
                  chan_task_running(emu, next, tr);
                  break;
		case 'e':
		case 'p':
                  chan_task_stopped(emu, tr);
                  break;
		/* Additional nested transitions */
		case 'X':
		case 'E':
                  chan_task_switch(emu, prev, next);
                  break;
		default:
			  die("unexpected transition value %c\n", tr);
	}
}

static void
update_task(struct ovni_emu *emu)
{
	struct ovni_ethread *th = emu->cur_thread;
	struct task_stack *stack = &th->nanos6_task_stack;

	struct task *prev = task_get_running(stack);

	/* Update the emulator state, but don't modify the channels */
	update_task_state(emu);

	struct task *next = task_get_running(stack);

	int was_running = (prev != NULL);
	int runs_now = (next != NULL);
	char tr = expand_transition_value(emu, was_running, runs_now);

	/* Update the channels now */
	update_task_channels(emu, tr, prev, next);
}

static void
create_task(struct ovni_emu *emu)
{
	if(ovni_payload_size(emu->cur_ev) != 8)
		die("cannot create task: unexpected payload size\n");

	uint32_t task_id = emu->cur_ev->payload.u32[0];
	uint32_t type_id = emu->cur_ev->payload.u32[1];

	struct task_info *info = &emu->cur_proc->nanos6_task_info;

	task_create(info, type_id, task_id);
}

static void
pre_task(struct ovni_emu *emu)
{
	struct ovni_ethread *th;
	struct ovni_chan *chan_th;

	th = emu->cur_thread;
	chan_th = &th->chan[CHAN_NANOS6_SUBSYSTEM];

	switch(emu->cur_ev->header.value)
	{
		/* We use the 'c' event to create the task and switch
		 * the subsystem all in one step because the timing here
		 * is critical. */
		case 'c':
			chan_push(chan_th, ST_NANOS6_TASK_CREATING);
			create_task(emu);
			break;
		case 'C':
			chan_pop(chan_th, ST_NANOS6_TASK_CREATING);
			break;
		case 'x':
		case 'e':
		case 'r':
		case 'p': /* Wet floor */
			update_task(emu);
			break;
		default:
			die("unexpected event value %c\n",
					emu->cur_ev->header.value);
	}
}

static void
pre_type(struct ovni_emu *emu)
{
	if(emu->cur_ev->header.value != 'c')
		die("unexpected event value %c\n",
				emu->cur_ev->header.value);

	if((emu->cur_ev->header.flags & OVNI_EV_JUMBO) == 0)
		die("expecting a jumbo event\n");

	uint8_t *data = &emu->cur_ev->payload.jumbo.data[0];
	uint32_t typeid = *(uint32_t *) data;
	data += 4;

	const char *label = (const char *) data;

	struct ovni_eproc *proc = emu->cur_proc;

	task_type_create(&proc->nanos6_task_info, typeid, label);
}

static void
pre_deps(struct ovni_emu *emu)
{
	struct ovni_ethread *th;
	struct ovni_chan *chan_th;

	th = emu->cur_thread;
	chan_th = &th->chan[CHAN_NANOS6_SUBSYSTEM];

	switch(emu->cur_ev->header.value)
	{
		case 'r': chan_push(chan_th, ST_NANOS6_DEP_REG); break;
		case 'R': chan_pop (chan_th, ST_NANOS6_DEP_REG); break;
		case 'u': chan_push(chan_th, ST_NANOS6_DEP_UNREG); break;
		case 'U': chan_pop (chan_th, ST_NANOS6_DEP_UNREG); break;
		default: break;
	}
}

static void
pre_blocking(struct ovni_emu *emu)
{
	struct ovni_ethread *th;
	struct ovni_chan *chan_th;

	th = emu->cur_thread;
	chan_th = &th->chan[CHAN_NANOS6_SUBSYSTEM];

	switch(emu->cur_ev->header.value)
	{
		case 'b': chan_push(chan_th, ST_NANOS6_BLK_BLOCKING); break;
		case 'B': chan_pop (chan_th, ST_NANOS6_BLK_BLOCKING); break;
		case 'u': chan_push(chan_th, ST_NANOS6_BLK_UNBLOCKING); break;
		case 'U': chan_pop (chan_th, ST_NANOS6_BLK_UNBLOCKING); break;
		case 'w': chan_push(chan_th, ST_NANOS6_BLK_TASKWAIT); break;
		case 'W': chan_pop (chan_th, ST_NANOS6_BLK_TASKWAIT); break;
		case 'f': chan_push(chan_th, ST_NANOS6_BLK_WAITFOR); break;
		case 'F': chan_pop (chan_th, ST_NANOS6_BLK_WAITFOR); break;
		default: break;
	}
}

static void
pre_sched(struct ovni_emu *emu)
{
	struct ovni_ethread *th;
	struct ovni_chan *chan_th;

	th = emu->cur_thread;
	chan_th = &th->chan[CHAN_NANOS6_SUBSYSTEM];

	switch(emu->cur_ev->header.value)
	{
		case 'h': chan_push(chan_th, ST_NANOS6_SCHED_HUNGRY); break;
		case 'f': chan_pop(chan_th, ST_NANOS6_SCHED_HUNGRY); break;
		case '[': chan_push(chan_th, ST_NANOS6_SCHED_SERVING); break;
		case ']': chan_pop(chan_th, ST_NANOS6_SCHED_SERVING); break;
		case '@': chan_ev(chan_th, EV_NANOS6_SCHED_SELF); break;
		case 'r': chan_ev(chan_th, EV_NANOS6_SCHED_RECV); break;
		case 's': chan_ev(chan_th, EV_NANOS6_SCHED_SEND); break;
		default: break;
	}
}

static void
pre_thread(struct ovni_emu *emu)
{
	struct ovni_ethread *th;
	struct ovni_chan *chan_th;

	th = emu->cur_thread;
	chan_th = &th->chan[CHAN_NANOS6_THREAD];

	switch(emu->cur_ev->header.value)
	{
		case 'e': chan_push(chan_th, ST_NANOS6_TH_EXTERNAL); break;
		case 'E': chan_pop (chan_th, ST_NANOS6_TH_EXTERNAL); break;
		case 'w': chan_push(chan_th, ST_NANOS6_TH_WORKER); break;
		case 'W': chan_pop (chan_th, ST_NANOS6_TH_WORKER); break;
		case 'l': chan_push(chan_th, ST_NANOS6_TH_LEADER); break;
		case 'L': chan_pop (chan_th, ST_NANOS6_TH_LEADER); break;
		case 'm': chan_push(chan_th, ST_NANOS6_TH_MAIN); break;
		case 'M': chan_pop (chan_th, ST_NANOS6_TH_MAIN); break;
		default: break;
	}
}

static void
pre_ss(struct ovni_emu *emu, int st)
{
	struct ovni_ethread *th;
	struct ovni_chan *chan_th;

	th = emu->cur_thread;
	chan_th = &th->chan[CHAN_NANOS6_SUBSYSTEM];

	dbg("pre_ss chan id %d st=%d\n", chan_th->id, st);

	switch(emu->cur_ev->header.value)
	{
		case '[': chan_push(chan_th, st); break;
		case ']': chan_pop(chan_th, st); break;
		default:
			err("unexpected value '%c' (expecting '[' or ']')\n",
					emu->cur_ev->header.value);
			abort();
	}
}

static void
check_affinity(struct ovni_emu *emu)
{
	struct ovni_ethread *th = emu->cur_thread;
	struct ovni_cpu *cpu = th->cpu;

	if(!cpu || cpu->virtual)
		return;

	if(cpu->nrunning_threads > 1)
	{
		die("cpu %s has more than one thread running\n",
				cpu->name);
	}
}

void
hook_pre_nanos6(struct ovni_emu *emu)
{
	if(emu->cur_ev->header.model != '6')
		die("hook_pre_nanos6: unexpected event with model %c\n",
				emu->cur_ev->header.model);

	if(!emu->cur_thread->is_active)
		die("hook_pre_nanos6: current thread %d not active\n",
				emu->cur_thread->tid);

	switch(emu->cur_ev->header.category)
	{
		case 'T': pre_task(emu); break;
		case 'Y': pre_type(emu); break;
		case 'S': pre_sched(emu); break;
		case 'U': pre_ss(emu, ST_NANOS6_TASK_SUBMIT); break;
		case 'H': pre_thread(emu); break;
		case 'D': pre_deps(emu); break;
		case 'B': pre_blocking(emu); break;
		default:
			break;
	}

	check_affinity(emu);
}

static void
end_lint(struct ovni_emu *emu)
{
	/* Ensure we run out of subsystem states */
	for(size_t i = 0; i < emu->total_nthreads; i++)
	{
		struct ovni_ethread *th = emu->global_thread[i];
		struct ovni_chan *ch = &th->chan[CHAN_NANOS6_SUBSYSTEM];
		if(ch->n != 1)
		{
			int top = ch->stack[ch->n - 1];

			struct pcf_value_label *pv;
			char *name = "(unknown)";
			for(pv = &nanos6_ss_values[0]; pv->label; pv++)
			{
				if(pv->value == top)
				{
					name = pv->label;
					break;
				}
			}

			die("thread %d ended with %d extra stacked nanos6 subsystems, top=\"%s\"\n",
					th->tid, ch->n - 1, name);
		}
	}
}

void
hook_end_nanos6(struct ovni_emu *emu)
{
	/* Emit types for all channel types and processes */
	for(enum chan_type ct = 0; ct < CHAN_MAXTYPE; ct++)
	{
		struct pcf_file *pcf = &emu->pcf[ct];
		int typeid = chan_to_prvtype[CHAN_NANOS6_TYPE];
		struct pcf_type *pcftype = pcf_find_type(pcf, typeid);

		for(size_t i = 0; i < emu->trace.nlooms; i++)
		{
			struct ovni_loom *loom = &emu->trace.loom[i];
			for(size_t j = 0; j < loom->nprocs; j++)
			{
				struct ovni_eproc *proc = &loom->proc[j];
				task_create_pcf_types(pcftype, proc->nanos6_task_info.types);
			}
		}
	}

	/* When running in linter mode perform additional checks */
	if(emu->enable_linter)
		end_lint(emu);
}