#define _GNU_SOURCE
#include <unistd.h>

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <linux/limits.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <stdatomic.h>
#include <assert.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>

#include "ovni.h"
#include "ovni_trace.h"

#define ENABLE_DEBUG

#ifdef ENABLE_DEBUG
#define dbg(...) fprintf(stderr, __VA_ARGS__);
#else
#define dbg(...)
#endif

#define err(...) fprintf(stderr, __VA_ARGS__);

//#define ENABLE_SLOW_CHECKS

//#define USE_RDTSC

/* Data per process */
struct ovni_rproc rproc = {0};

/* Data per thread */
_Thread_local struct ovni_rthread rthread = {0};

static int
create_trace_dirs(char *tracedir, int loom, int proc)
{
	char path[PATH_MAX];

	fprintf(stderr, "create trace dirs for loom=%d, proc=%d\n",
			loom, proc);

	snprintf(path, PATH_MAX, "%s", tracedir);

	if(mkdir(path, 0755))
	{
		fprintf(stderr, "mkdir %s: %s\n", path, strerror(errno));
		//return -1;
	}

	snprintf(path, PATH_MAX, "%s/loom.%d", tracedir, loom);

	if(mkdir(path, 0755))
	{
		fprintf(stderr, "mkdir %s: %s\n", path, strerror(errno));
		//return -1;
	}

	snprintf(rproc.dir, PATH_MAX, "%s/loom.%d/proc.%d", tracedir, loom, proc);

	if(mkdir(rproc.dir, 0755))
	{
		fprintf(stderr, "mkdir %s: %s\n", rproc.dir, strerror(errno));
		return -1;
	}

	return 0;
}

static int
create_trace_stream()
{
	int fd;
	char path[PATH_MAX];

	fprintf(stderr, "create thread stream tid=%d gettid=%d rproc.proc=%d rproc.ready=%d\n",
			rthread.tid, gettid(), rproc.proc, rproc.ready);

	snprintf(path, PATH_MAX, "%s/thread.%d", rproc.dir, rthread.tid);

	//rthread.streamfd = open(path, O_WRONLY | O_CREAT | O_DSYNC, 0644);
	rthread.streamfd = open(path, O_WRONLY | O_CREAT, 0644);

	if(rthread.streamfd == -1)
	{
		fprintf(stderr, "open %s failed: %s\n", path, strerror(errno));
		/* Shall we just return -1 ? */
		abort();
		//return -1;
	}

	return 0;
}

int
ovni_proc_init(int loom, int proc)
{
	int i;

	assert(rproc.ready == 0);

	memset(&rproc, 0, sizeof(rproc));

	rproc.loom = loom;
	rproc.proc = proc;

	/* By default we use the monotonic clock */
	rproc.clockid = CLOCK_MONOTONIC;

	if(create_trace_dirs(OVNI_TRACEDIR, loom, proc))
		abort();

	rproc.ready = 1;

	return 0;
}

int
ovni_thread_init(pid_t tid)
{
	int i;

	assert(tid != 0);

	if(rthread.ready)
	{
		fprintf(stderr, "warning: thread tid=%d already initialized\n",
				tid);
		return 0;
	}

	assert(rthread.ready == 0);
	assert(rthread.tid == 0);
	assert(rthread.cpu == 0);
	assert(rproc.ready == 1);

	fprintf(stderr, "ovni thread init tid=%d\n", tid);

	memset(&rthread, 0, sizeof(rthread));

	rthread.tid = tid;
	rthread.cpu = -666;
	rthread.evlen = 0;

	rthread.evbuf = malloc(OVNI_MAX_EV_BUF);
	if(rthread.evbuf == NULL)
	{
		perror("malloc");
		abort();
	}

	if(create_trace_stream(tid))
		abort();

	rthread.ready = 1;

	return 0;
}

int
ovni_thread_free()
{
	assert(rthread.ready);
	free(rthread.evbuf);
}

int
ovni_thread_isready()
{
	return rthread.ready;
}

void
ovni_cpu_set(int cpu)
{
	rthread.cpu = cpu;
}

static inline
uint64_t rdtsc(void)
{
    uint32_t lo, hi;

    // RDTSC copies contents of 64-bit TSC into EDX:EAX
    asm volatile("rdtsc" : "=a" (lo), "=d" (hi));
    return (uint64_t) hi << 32 | lo;
}

uint64_t
ovni_get_clock()
{
	struct timespec tp;
	uint64_t ns = 1000LL * 1000LL * 1000LL;
	uint64_t raw;
	int ret;

#ifdef USE_RDTSC
	raw = rdtsc();
#else

	ret = clock_gettime(rproc.clockid, &tp);

#ifdef ENABLE_SLOW_CHECKS
	if(ret) abort();
#endif /* ENABLE_SLOW_CHECKS */

	raw = tp.tv_sec * ns + tp.tv_nsec;
	rthread.clockvalue = (uint64_t) raw;

#endif /* USE_RDTSC */

	return raw;
}

/* Sets the current time so that all subsequent events have the new
 * timestamp */
void
ovni_clock_update()
{
	rthread.clockvalue = ovni_get_clock();
}

static void
hexdump(uint8_t *buf, size_t size)
{
	int i, j;

	//printf("writing %ld bytes in cpu=%d\n", size, rthread.cpu);

	for(i=0; i<size; i+=16)
	{
		for(j=0; j<16 && i+j < size; j++)
		{
			dbg("%02x ", buf[i+j]);
		}
		dbg("\n");
	}
}

static int
ovni_write(uint8_t *buf, size_t size)
{
	ssize_t written;

	do
	{
		written = write(rthread.streamfd, buf, size);

		if(written < 0)
		{
			perror("write");
			return -1;
		}

		size -= written;
		buf += written;
	} while(size > 0);

	return 0;
}

static int
flush_evbuf()
{
	int ret;

	assert(rthread.ready);
	assert(rproc.ready);

	ret = ovni_write(rthread.evbuf, rthread.evlen);

	rthread.evlen = 0;

	return ret;
}

static void
ovni_ev_set_clock(struct ovni_ev *ev)
{
	ev->header.clock_lo = (uint32_t) (rthread.clockvalue & 0xffffffff);
	ev->header.clock_hi = (uint16_t) ((rthread.clockvalue >> 32) & 0xffff);
}

uint64_t
ovni_ev_get_clock(struct ovni_ev *ev)
{
	uint64_t clock;

	clock = ((uint64_t) ev->header.clock_hi) << 32 | ((uint64_t) ev->header.clock_lo);
	return clock;
}

void
ovni_ev_set_mcv(struct ovni_ev *ev, char *mcv)
{
	ev->header.model = mcv[0];
	ev->header.class = mcv[1];
	ev->header.value = mcv[2];
}

static size_t
get_jumbo_payload_size(struct ovni_ev *ev)
{
	return sizeof(ev->payload.jumbo.size) + ev->payload.jumbo.size;
}

int
ovni_payload_size(struct ovni_ev *ev)
{
	int size;

	if(ev->header.flags & OVNI_EV_JUMBO)
		return get_jumbo_payload_size(ev);

	size = ev->header.flags & 0x0f;

	if(size == 0)
		return 0;

	/* The minimum size is 2 bytes, so we can encode a length of 16
	 * bytes using 4 bits (0x0f) */
	size++;

	return size;
}

void
ovni_payload_add(struct ovni_ev *ev, uint8_t *buf, int size)
{
	int payload_size;

	assert((ev->header.flags & OVNI_EV_JUMBO) == 0);
	assert(size >= 2);

	payload_size = ovni_payload_size(ev);

	/* Ensure we have room */
	assert(payload_size + size <= sizeof(ev->payload));

	memcpy(&ev->payload.u8[payload_size], buf, size);
	payload_size += size;

	ev->header.flags = ev->header.flags & 0xf0 | (payload_size-1) & 0x0f;
}

int
ovni_ev_size(struct ovni_ev *ev)
{
	return sizeof(ev->header) + ovni_payload_size(ev);
}

static void
ovni_ev_add(struct ovni_ev *ev);

int
ovni_flush()
{
	int ret = 0;
	struct ovni_ev pre={0}, post={0};

	assert(rthread.ready);
	assert(rproc.ready);

	ovni_clock_update();
	ovni_ev_set_clock(&pre);
	ovni_ev_set_mcv(&pre, "OF[");

	ret = flush_evbuf();

	ovni_clock_update();
	ovni_ev_set_clock(&post);
	ovni_ev_set_mcv(&post, "OF]");

	/* Add the two flush events */
	ovni_ev_add(&pre);
	ovni_ev_add(&post);

	return ret;
}

void
ovni_ev_add_jumbo(struct ovni_ev *ev, uint8_t *buf, uint32_t bufsize)
{
	size_t evsize, totalsize;

	assert(ovni_payload_size(ev) == 0);

	ovni_payload_add(ev, (uint8_t *) &bufsize, sizeof(bufsize));
	evsize = ovni_ev_size(ev);

	totalsize = evsize + bufsize;

	/* Check if the event fits or flush first otherwise */
	if(rthread.evlen + totalsize >= OVNI_MAX_EV_BUF)
		ovni_flush();

	/* Se the jumbo flag here, so we capture the previous evsize
	 * properly, ignoring the jumbo buffer */
	ev->header.flags |= OVNI_EV_JUMBO;

	memcpy(&rthread.evbuf[rthread.evlen], ev, evsize);
	rthread.evlen += evsize;
	memcpy(&rthread.evbuf[rthread.evlen], buf, bufsize);
	rthread.evlen += bufsize;

	assert(rthread.evlen < OVNI_MAX_EV_BUF);
}


static void
ovni_ev_add(struct ovni_ev *ev)
{
	int size;	

	size = ovni_ev_size(ev);

	/* Check if the event fits or flush first otherwise */
	if(rthread.evlen + size >= OVNI_MAX_EV_BUF)
		ovni_flush();

	memcpy(&rthread.evbuf[rthread.evlen], ev, size);
	rthread.evlen += size;
}

void
ovni_ev_jumbo(struct ovni_ev *ev, uint8_t *buf, uint32_t bufsize)
{
	ovni_ev_set_clock(ev);
	ovni_ev_add_jumbo(ev, buf, bufsize);
}

void
ovni_ev(struct ovni_ev *ev)
{
	ovni_ev_set_clock(ev);
	ovni_ev_add(ev);
}

static int
find_dir_prefix(struct dirent *dirent, const char *prefix, int *num)
{
	const char *p;

	p = dirent->d_name;

	/* Check the prefix */
	if(strncmp(p, prefix, strlen(prefix)) != 0)
		return -1;

	p += strlen(prefix);

	/* Find the dot */
	if(*p != '.')
		return -1;

	p++;

	/* Convert the end to a number */
	*num = atoi(p);

	return 0;
}

static int
load_thread(struct ovni_ethread *thread, struct ovni_eproc *proc, int index, int tid, char *filepath)
{
	static int total_threads = 0;

	thread->tid = tid;
	thread->index = index;
	thread->gindex = total_threads++;
	thread->state = TH_ST_UNKNOWN;
	thread->proc = proc;
	thread->stream_fd = open(filepath, O_RDONLY);

	if(thread->stream_fd == -1)
	{
		perror("open");
		return -1;
	}
	return 0;
}

static int
load_proc(struct ovni_eproc *proc, int index, int pid, char *procdir)
{
	static int total_procs = 0;

	struct dirent *dirent;
	DIR *dir;
	char path[PATH_MAX];
	struct ovni_ethread *thread;
	int tid;

	proc->pid = pid;
	proc->index = index;
	proc->gindex = total_procs++;

	if((dir = opendir(procdir)) == NULL)
	{
		fprintf(stderr, "opendir %s failed: %s\n",
				procdir, strerror(errno));
		return -1;
	}

	while((dirent = readdir(dir)) != NULL)
	{
		if(find_dir_prefix(dirent, "thread", &tid) != 0)
		{
			err("warning: ignoring bogus directory entry %s\n",
					dirent->d_name);
			continue;
		}

		sprintf(path, "%s/%s", procdir, dirent->d_name);

		if(proc->nthreads >= OVNI_MAX_THR)
		{
			err("too many thread streams for process %d\n", pid);
			abort();
		}

		thread = &proc->thread[proc->nthreads];

		if(load_thread(thread, proc, proc->nthreads, tid, path) != 0)
			return -1;

		proc->nthreads++;
	}

	closedir(dir);

	return 0;
}

static int
load_loom(struct ovni_loom *loom, int loomid, char *loomdir)
{
	int pid;
	char path[PATH_MAX];
	struct stat st;
	DIR *dir;
	struct dirent *dirent;
	struct ovni_eproc *proc;

	if((dir = opendir(loomdir)) == NULL)
	{
		fprintf(stderr, "opendir %s failed: %s\n",
				loomdir, strerror(errno));
		return -1;
	}

	while((dirent = readdir(dir)) != NULL)
	{
		if(find_dir_prefix(dirent, "proc", &pid) != 0)
		{
			err("warning: ignoring bogus directory entry %s\n",
					dirent->d_name);
			continue;
		}

		sprintf(path, "%s/%s", loomdir, dirent->d_name);

		if(loom->nprocs >= OVNI_MAX_PROC)
		{
			err("too many process streams for loom %d\n",
					loomid);
			abort();
		}

		proc = &loom->proc[loom->nprocs];

		if(load_proc(proc, loom->nprocs, pid, path) != 0)
			return -1;

		loom->nprocs++;
	}

	closedir(dir);

	return 0;
}

int
ovni_load_trace(struct ovni_trace *trace, char *tracedir)
{
	int loom, nlooms;
	char path[PATH_MAX];

	/* TODO: For now only one loom */
	nlooms = 1;
	loom = 0;

	sprintf(path, "%s/loom.%d", tracedir, loom);

	if(load_loom(&trace->loom[loom], loom, path))
		return -1;

	trace->nlooms = nlooms;

	return 0;
}

static int
load_stream_buf(struct ovni_stream *stream, struct ovni_ethread *thread)
{
	struct stat st;

	if(fstat(thread->stream_fd, &st) < 0)
	{
		perror("fstat");
		return -1;
	}

	stream->size = st.st_size;
	stream->buf = mmap(NULL, stream->size, PROT_READ, MAP_SHARED,
			thread->stream_fd, 0);

	if(stream->buf == MAP_FAILED)
	{
		perror("mmap");
		return -1;
	}

	return 0;
}

/* Populates the streams in a single array */
int
ovni_load_streams(struct ovni_trace *trace)
{
	int i, j, k, s;
	struct ovni_loom *loom;
	struct ovni_eproc *proc;
	struct ovni_ethread *thread;
	struct ovni_stream *stream;

	trace->nstreams = 0;

	for(i=0; i<trace->nlooms; i++)
	{
		loom = &trace->loom[i];
		for(j=0; j<loom->nprocs; j++)
		{
			proc = &loom->proc[j];
			for(k=0; k<proc->nthreads; k++)
			{
				trace->nstreams++;
			}
		}
	}

	trace->stream = calloc(trace->nstreams, sizeof(struct ovni_stream));

	if(trace->stream == NULL)
	{
		perror("calloc");
		return -1;
	}

	fprintf(stderr, "loaded %d streams\n", trace->nstreams);

	for(s=0, i=0; i<trace->nlooms; i++)
	{
		loom = &trace->loom[i];
		for(j=0; j<loom->nprocs; j++)
		{
			proc = &loom->proc[j];
			for(k=0; k<proc->nthreads; k++)
			{
				thread = &proc->thread[k];
				stream = &trace->stream[s++];

				if(load_stream_buf(stream, thread) != 0)
				{
					err("load_stream_buf failed\n");
					return -1;
				}

				stream->tid = thread->tid;
				stream->thread = k;
				stream->proc = j;
				stream->loom = i;
				stream->active = 1;
				stream->lastclock = 0;
				stream->offset = 0;
				stream->cur_ev = NULL;
			}
		}
	}

	return 0;
}

void
ovni_free_streams(struct ovni_trace *trace)
{
	free(trace->stream);
}

int
ovni_load_next_event(struct ovni_stream *stream)
{
	int i;
	size_t n, size;
	uint8_t flags;

	if(stream->active == 0)
	{
		dbg("stream is inactive, cannot load more events\n");
		return -1;
	}

	if(stream->cur_ev == NULL)
	{
		stream->cur_ev = (struct ovni_ev *) stream->buf;
		stream->offset = 0;
		dbg("first event\n");
		goto out;
	}

	//printf("advancing offset %ld bytes\n", ovni_ev_size(stream->cur_ev));
	stream->offset += ovni_ev_size(stream->cur_ev);

	/* We have reached the end */
	if(stream->offset == stream->size)
	{
		stream->active = 0;
		dbg("stream runs out of events\n");
		return -1;
	}

	/* It cannot overflow, otherwise we are reading garbage */
	assert(stream->offset < stream->size);

	stream->cur_ev = (struct ovni_ev *) &stream->buf[stream->offset];

out:

	//dbg("---------\n");
	//dbg("ev size = %d\n", ovni_ev_size(stream->cur_ev));
	//dbg("ev flags = %02x\n", stream->cur_ev->header.flags);
	//dbg("loaded next event:\n");
	//hexdump((uint8_t *) stream->cur_ev, ovni_ev_size(stream->cur_ev));
	//dbg("---------\n");

	return 0;
}