/*
	todo:
	- write out logs at startup directly
	- scheme:// prefix
	- LI_LOG_LEVEL_ABORT: write message immediately, as the log write is followed by an abort()

*/

#include <lighttpd/base.h>
#include <lighttpd/plugin_core.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdarg.h>

#define LOG_DEFAULT_TS_FORMAT "%d/%b/%Y %T %Z"
#define LOG_DEFAULT_TTL 30.0

static void log_watcher_cb(struct ev_loop *loop, ev_async *w, int revents);

static void li_log_write_stderr(liServer *srv, const gchar *msg, gboolean newline) {
	gsize s;
	struct tm tm;
	time_t now = (time_t) ev_time();
	gchar buf[128];
	GStaticMutex mtx = G_STATIC_MUTEX_INIT;

	UNUSED(srv);

#ifdef HAVE_LOCALTIME_R
	s = strftime(buf, sizeof(buf), LOG_DEFAULT_TS_FORMAT, localtime_r(&now, &tm));
#else
	s = strftime(buf, sizeof(buf), LOG_DEFAULT_TS_FORMAT, localtime(&now));
#endif

	buf[s] = '\0';

	g_static_mutex_lock(&mtx);
	g_printerr(newline ? "%s %s\n" : "%s %s", buf, msg);
	g_static_mutex_unlock(&mtx);
}

static liLog *log_open(liServer *srv, GString *path) {
	liLog *log;

	if (path)
		log = li_radixtree_lookup_exact(srv->logs.targets, path->str, path->len * 8);
	else
		log = NULL;

	if (!log) {
		/* log not open */
		gint fd = -1;
		liLogType type = li_log_type_from_path(path);

		switch (type) {
			case LI_LOG_TYPE_STDERR:
				fd = STDERR_FILENO;
				break;
			case LI_LOG_TYPE_FILE:
				/* todo: open via angel */
				fd = open(path->str, O_RDWR | O_CREAT | O_APPEND, 0660);
				if (fd == -1) {
					int err = errno;
					GString *str = g_string_sized_new(255);
					g_string_append_printf(str, "(error) %s.%d: failed to open log file '%s': %s", LI_REMOVE_PATH(__FILE__), __LINE__, path->str, g_strerror(err));
					/* li_log_write_stderr(srv, str->str, TRUE); */
					g_string_free(str, TRUE);
					return NULL;
				}
				break;
			case LI_LOG_TYPE_PIPE:
			case LI_LOG_TYPE_SYSLOG:
				/* todo */
				assert(NULL);
			case LI_LOG_TYPE_NONE:
				return NULL;
		}

		log = g_slice_new0(liLog);
		log->type = type;
		log->path = g_string_new_len(GSTR_LEN(path));
		log->fd = fd;
		log->wqelem.data = log;
		li_radixtree_insert(srv->logs.targets, log->path->str, log->path->len * 8, log);
		/*g_print("log_open(\"%s\")\n", log->path->str);*/
	}

	li_waitqueue_push(&srv->logs.close_queue, &log->wqelem);

	return log;
}

static void log_close(liServer *srv, liLog *log) {
	li_radixtree_remove(srv->logs.targets, log->path->str, log->path->len * 8);
	li_waitqueue_remove(&srv->logs.close_queue, &log->wqelem);

	if (log->type == LI_LOG_TYPE_FILE || log->type == LI_LOG_TYPE_PIPE) {
		close(log->fd);
	}

	/*g_print("log_close(\"%s\")\n", log->path->str);*/
	g_string_free(log->path, TRUE);

	g_slice_free(liLog, log);
}

static void log_close_cb(liWaitQueue *wq, gpointer data) {
	/* callback for the close queue */
	liServer *srv = (liServer*) data;
	liWaitQueueElem *wqe;

	while ((wqe = li_waitqueue_pop(wq)) != NULL) {
		log_close(srv, wqe->data);
	}

	li_waitqueue_update(wq);
}

void li_log_init(liServer *srv) {
	srv->logs.loop = ev_loop_new(EVFLAG_AUTO);
	ev_async_init(&srv->logs.watcher, log_watcher_cb);
	srv->logs.watcher.data = srv;
	srv->logs.targets = li_radixtree_new();
	li_waitqueue_init(&srv->logs.close_queue, srv->logs.loop, log_close_cb, LOG_DEFAULT_TTL, srv);
	srv->logs.timestamps = g_array_new(FALSE, FALSE, sizeof(liLogTimestamp*));
	srv->logs.thread_alive = FALSE;
	g_queue_init(&srv->logs.write_queue);
	g_static_mutex_init(&srv->logs.write_queue_mutex);

	/* first entry in srv->logs.timestamps is the default timestamp */
	li_log_timestamp_new(srv, g_string_new_len(CONST_STR_LEN(LOG_DEFAULT_TS_FORMAT)));
}

void li_log_cleanup(liServer *srv) {
	guint i;
	liLogTimestamp *ts;

	/* wait for logging thread to exit */
	if (g_atomic_int_get(&srv->logs.thread_alive) == TRUE)
	{
		li_log_thread_finish(srv);
		g_thread_join(srv->logs.thread);
	}

	li_radixtree_free(srv->logs.targets, NULL, NULL);

	for (i = 0; i < srv->logs.timestamps->len; i++) {
		ts = g_array_index(srv->logs.timestamps, liLogTimestamp*, i);
		/*g_print("ts #%d refcount: %d\n", i, ts->refcount);*/
		if (li_log_timestamp_free(srv, g_array_index(srv->logs.timestamps, liLogTimestamp*, 0)))
			i--;
	}

	g_array_free(srv->logs.timestamps, TRUE);
	ev_loop_destroy(srv->logs.loop);
}

gboolean li_log_write_direct(liServer *srv, liVRequest *vr, GString *path, GString *msg) {
	liLogEntry *log_entry;
	liWorker *wrk;

	log_entry = g_slice_new(liLogEntry);
	log_entry->path = g_string_new_len(GSTR_LEN(path));
	log_entry->ts = NULL;
	log_entry->level = 0;
	log_entry->flags = 0;
	log_entry->msg = msg;
	log_entry->queue_link.data = log_entry;
	log_entry->queue_link.next = NULL;
	log_entry->queue_link.prev = NULL;

	if (G_LIKELY(vr)) {
		/* push onto local worker log queue */
		wrk = vr->wrk;
		g_queue_push_tail_link(&wrk->log_queue, &log_entry->queue_link);
	} else {
		/* no worker context, push directly onto global log queue */
		g_static_mutex_lock(&srv->logs.write_queue_mutex);
		g_queue_push_tail_link(&srv->logs.write_queue, &log_entry->queue_link);
		g_static_mutex_unlock(&srv->logs.write_queue_mutex);
		ev_async_send(srv->logs.loop, &srv->logs.watcher);
	}

	return TRUE;
}

gboolean li_log_write(liServer *srv, liVRequest *vr, liLogLevel log_level, guint flags, const gchar *fmt, ...) {
	liWorker *wrk;
	va_list ap;
	GString *log_line;
	liLogEntry *log_entry;
	liLogTimestamp *ts = NULL;
	GArray *logs = NULL;
	GString *path;

	if (vr != NULL) {
		wrk = vr->wrk;
		if (!srv) srv = wrk->srv;
		/* get log from connection */
		logs = CORE_OPTIONPTR(LI_CORE_OPTION_LOG).list;
		ts = CORE_OPTIONPTR(LI_CORE_OPTION_LOG_TS_FORMAT).ptr;
	} else {
		liOptionPtrValue *ologval = NULL;
		wrk = NULL;
		if (0 + LI_CORE_OPTION_LOG < srv->optionptr_def_values->len) {
			ologval = g_array_index(srv->optionptr_def_values, liOptionPtrValue*, 0 + LI_CORE_OPTION_LOG);
		}

		if (ologval != NULL)
			logs = ologval->data.list;
	}

	if (logs != NULL && log_level < logs->len) {
		path = g_array_index(logs, GString*, log_level);
	} else {
		return FALSE;
	}

	if (NULL == ts && srv->logs.timestamps->len > 0) {
		ts = g_array_index(srv->logs.timestamps, liLogTimestamp*, 0);
	}

	log_line = g_string_sized_new(63);
	va_start(ap, fmt);
	g_string_vprintf(log_line, fmt, ap);
	va_end(ap);

	if (!path) {
		li_log_write_stderr(srv, log_line->str, TRUE);
		g_string_free(log_line, TRUE);
		return TRUE;
	}

	switch (g_atomic_int_get(&srv->state)) {
	case LI_SERVER_INIT:
	case LI_SERVER_LOADING:
	case LI_SERVER_SUSPENDED:
	case LI_SERVER_WARMUP:
	case LI_SERVER_STOPPING:
	case LI_SERVER_DOWN:
		li_log_write_stderr(srv, log_line->str, TRUE);
		g_string_free(log_line, TRUE);
		return TRUE;
	default:
		break;
	}

	log_entry = g_slice_new(liLogEntry);
	log_entry->path = g_string_new_len(GSTR_LEN(path));
	log_entry->ts = ts;
	log_entry->level = log_level;
	log_entry->flags = flags;
	log_entry->msg = log_line;
	log_entry->queue_link.data = log_entry;
	log_entry->queue_link.next = NULL;
	log_entry->queue_link.prev = NULL;

	if (G_LIKELY(wrk)) {
		/* push onto local worker log queue */
		g_queue_push_tail_link(&wrk->log_queue, &log_entry->queue_link);
	} else {
		/* no worker context, push directly onto global log queue */
		g_static_mutex_lock(&srv->logs.write_queue_mutex);
		g_queue_push_tail_link(&srv->logs.write_queue, &log_entry->queue_link);
		g_static_mutex_unlock(&srv->logs.write_queue_mutex);
		ev_async_send(srv->logs.loop, &srv->logs.watcher);
	}

	return TRUE;
}

static gpointer log_thread(liServer *srv) {
	ev_loop(srv->logs.loop, 0);
	return NULL;
}

static GString *log_timestamp_format(liServer *srv, liLogTimestamp *ts) {
	gsize s;
	struct tm tm;
	time_t now = (time_t) ev_now(srv->logs.loop);

	/* cache hit */
	if (now == ts->last_ts)
		return ts->cached;

#ifdef HAVE_LOCALTIME_R
	s = strftime(ts->cached->str, ts->cached->allocated_len, ts->format->str, localtime_r(&now, &tm));
#else
	s = strftime(ts->cached->str, ts->cached->allocated_len, ts->format->str, localtime(&now));
#endif

	g_string_set_size(ts->cached, s);
	ts->last_ts = now;

	return ts->cached;
}

static void log_watcher_cb(struct ev_loop *loop, ev_async *w, int revents) {
	liServer *srv = (liServer*) w->data;
	liLog *log;
	liLogEntry *log_entry;
	GList *queue_link, *queue_link_next;
	GString *msg;
	gssize bytes_written;
	gssize write_res;

	UNUSED(loop);
	UNUSED(revents);

	if (g_atomic_int_get(&srv->logs.thread_stop) == TRUE) {
		liWaitQueueElem *wqe;

		while ((wqe = li_waitqueue_pop_force(&srv->logs.close_queue)) != NULL) {
			log_close(srv, wqe->data);
		}
		li_waitqueue_stop(&srv->logs.close_queue);
		ev_async_stop(srv->logs.loop, &srv->logs.watcher);
		return;
	}

	/* pop everything from global write queue */
	g_static_mutex_lock(&srv->logs.write_queue_mutex);
	queue_link = g_queue_peek_head_link(&srv->logs.write_queue);
	g_queue_init(&srv->logs.write_queue);
	g_static_mutex_unlock(&srv->logs.write_queue_mutex);

	while (queue_link) {
		log_entry = queue_link->data;
		log = log_open(srv, log_entry->path);
		msg = log_entry->msg;
		bytes_written = 0;

		if (!log) {
			li_log_write_stderr(srv, log_entry->msg->str, TRUE);
			goto next;
		}

		if (log_entry->flags & LOG_FLAG_TIMESTAMP) {
			log_timestamp_format(srv, log_entry->ts);
			g_string_prepend_c(msg, ' ');
			g_string_prepend_len(msg, GSTR_LEN(log_entry->ts->cached));
		}

		g_string_append_len(msg, CONST_STR_LEN("\n"));

		/* todo: support for other logtargets than files */
		while (bytes_written < (gssize)msg->len) {
			write_res = write(log->fd, msg->str + bytes_written, msg->len - bytes_written);
			/* write_res = msg->len; */

			/* write() failed, check why */
			if (write_res == -1) {
				GString *str;
				int err = errno;

				switch (err) {
					case EAGAIN:
					case EINTR:
						continue;
				}

				str = g_string_sized_new(63);
				g_string_printf(str, "could not write to log '%s': %s\n", log_entry->path->str, g_strerror(err));
				li_log_write_stderr(srv, str->str, TRUE);
				li_log_write_stderr(srv, msg->str, TRUE);
				break;
			}
			else {
				bytes_written += write_res;
				assert(bytes_written <= (gssize) msg->len);
			}
		}

		next:
		queue_link_next = queue_link->next;
		g_string_free(log_entry->path, TRUE);
		g_string_free(log_entry->msg, TRUE);
		g_slice_free(liLogEntry, log_entry);
		queue_link = queue_link_next;
	}

	if (g_atomic_int_get(&srv->logs.thread_finish) == TRUE) {
		liWaitQueueElem *wqe;

		while ((wqe = li_waitqueue_pop_force(&srv->logs.close_queue)) != NULL) {
			log_close(srv, wqe->data);
		}
		li_waitqueue_stop(&srv->logs.close_queue);
		ev_async_stop(srv->logs.loop, &srv->logs.watcher);
		return;
	}

	return;
}

liLogType li_log_type_from_path(GString *path) {
	if (path->len == 0)
		return LI_LOG_TYPE_NONE;

	/* look for scheme:// paths */
	if (g_str_has_prefix(path->str, "file://"))
		return LI_LOG_TYPE_FILE;
	if (g_str_has_prefix(path->str, "pipe://"))
		return LI_LOG_TYPE_PIPE;
	if (g_str_has_prefix(path->str, "stderr://"))
		return LI_LOG_TYPE_STDERR;
	if (g_str_has_prefix(path->str, "syslog://"))
		return LI_LOG_TYPE_SYSLOG;

	/* targets starting with a slash are absolute paths and therefor file targets */
	if (*path->str == '/')
		return LI_LOG_TYPE_FILE;

	/* targets starting with a pipe are ... pipes! */
	if (*path->str == '|')
		return LI_LOG_TYPE_PIPE;

	if (g_str_equal(path->str, "stderr"))
		return LI_LOG_TYPE_STDERR;

	if (g_str_equal(path->str, "syslog"))
		return LI_LOG_TYPE_SYSLOG;

	/* fall back to stderr */
	return LI_LOG_TYPE_STDERR;
}

liLogLevel li_log_level_from_string(GString *str) {
	if (g_str_equal(str->str, "debug"))
		return LI_LOG_LEVEL_DEBUG;
	if (g_str_equal(str->str, "info"))
		return LI_LOG_LEVEL_INFO;
	if (g_str_equal(str->str, "warning"))
		return LI_LOG_LEVEL_WARNING;
	if (g_str_equal(str->str, "error"))
		return LI_LOG_LEVEL_ERROR;
	if (g_str_equal(str->str, "backend"))
		return LI_LOG_LEVEL_BACKEND;

	/* fall back to debug level */
	return LI_LOG_LEVEL_DEBUG;
}

gchar* li_log_level_str(liLogLevel log_level) {
	switch (log_level) {
		case LI_LOG_LEVEL_DEBUG:   return "debug";
		case LI_LOG_LEVEL_INFO:    return "info";
		case LI_LOG_LEVEL_WARNING: return "warning";
		case LI_LOG_LEVEL_ERROR:   return "error";
		case LI_LOG_LEVEL_BACKEND: return "backend";
		default:                   return "unknown";
	}
}

void li_log_thread_start(liServer *srv) {
	GError *err = NULL;

	ev_async_start(srv->logs.loop, &srv->logs.watcher);

	srv->logs.thread = g_thread_create((GThreadFunc)log_thread, srv, TRUE, &err);

	if (srv->logs.thread == NULL) {
		g_printerr("could not create logging thread: %s\n", err->message);
		g_error_free(err);
		abort();
	}

	g_atomic_int_set(&srv->logs.thread_alive, TRUE);
}

void li_log_thread_stop(liServer *srv) {
	if (g_atomic_int_get(&srv->logs.thread_alive) == TRUE) {
		g_atomic_int_set(&srv->logs.thread_stop, TRUE);
		li_log_thread_wakeup(srv);
	}
}

void li_log_thread_finish(liServer *srv) {
	if (g_atomic_int_get(&srv->logs.thread_alive) == TRUE) {
		g_atomic_int_set(&srv->logs.thread_finish, TRUE);
		li_log_thread_wakeup(srv);
	}
}

void li_log_thread_wakeup(liServer *srv) {
	if (!g_atomic_int_get(&srv->logs.thread_alive))
		li_log_thread_start(srv);

	ev_async_send(srv->logs.loop, &srv->logs.watcher);
}


liLogTimestamp *li_log_timestamp_new(liServer *srv, GString *format) {
	liLogTimestamp *ts;

	/* check if there already exists a timestamp entry with the same format */
	g_mutex_lock(srv->action_mutex);
	for (guint i = 0; i < srv->logs.timestamps->len; i++) {
		ts = g_array_index(srv->logs.timestamps, liLogTimestamp*, i);
		if (g_string_equal(ts->format, format)) {
			g_atomic_int_inc(&(ts->refcount));
			g_string_free(format, TRUE);
			g_mutex_unlock(srv->action_mutex);
			return ts;
		}
	}

	ts = g_slice_new(liLogTimestamp);

	ts->cached = g_string_sized_new(255);
	ts->last_ts = 0;
	ts->refcount = 1;
	ts->format = format;

	g_array_append_val(srv->logs.timestamps, ts);
	g_mutex_unlock(srv->action_mutex);

	return ts;
}

gboolean li_log_timestamp_free(liServer *srv, liLogTimestamp *ts) {
	if (g_atomic_int_dec_and_test(&(ts->refcount))) {
		g_mutex_lock(srv->action_mutex);

		for (guint i = 0; i < srv->logs.timestamps->len; i++) {
			if (g_string_equal(g_array_index(srv->logs.timestamps, liLogTimestamp*, i)->format, ts->format)) {
				g_array_remove_index_fast(srv->logs.timestamps, i);
				break;
			}
		}

		g_mutex_unlock(srv->action_mutex);
		g_string_free(ts->cached, TRUE);
		g_string_free(ts->format, TRUE);
		g_slice_free(liLogTimestamp, ts);
		return TRUE;
	}

	return FALSE;
}

void li_log_split_lines(liServer *srv, liVRequest *vr, liLogLevel log_level, guint flags, gchar *txt, const gchar *prefix) {
	gchar *start;

	start = txt;
	while ('\0' != *txt) {
		if ('\r' == *txt || '\n' == *txt) {
			*txt = '\0';
			if (txt - start > 1) { /* skip empty lines*/
				li_log_write(srv, vr, log_level, flags, "%s%s", prefix, start);
			}
			txt++;
			while (*txt == '\n' || *txt == '\r') txt++;
			start = txt;
		} else {
			txt++;
		}
	}
	if (txt - start > 1) { /* skip empty lines*/
		li_log_write(srv, vr, log_level, flags, "%s%s", prefix, start);
	}
}

void li_log_split_lines_(liServer *srv, liVRequest *vr, liLogLevel log_level, guint flags, gchar *txt, const gchar *fmt, ...) {
	va_list ap;
	GString *prefix;

	prefix = g_string_sized_new(0);
	va_start(ap, fmt);
	g_string_vprintf(prefix, fmt, ap);
	va_end(ap);

	li_log_split_lines(srv, vr, log_level, flags, txt, prefix->str);

	g_string_free(prefix, TRUE);
}