#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <byteswap.h>

enum log_flags {
	LOG_NOCONS      = 1,    /* already flushed, do not print to console */
        LOG_NEWLINE     = 2,    /* text ended with a newline */
        LOG_PREFIX      = 4,    /* text started with a prefix */
        LOG_CONT        = 8,    /* text is a fragment of a continuation line */
};

struct log {
        uint64_t ts_nsec;            /* timestamp in nanoseconds */
        uint16_t len;                /* length of entire record */
        uint16_t text_len;           /* length of text buffer */
        uint16_t dict_len;           /* length of dictionary buffer */
        uint8_t facility;            /* syslog facility */
	union {
		struct {
			uint8_t flags:5; /* internal record flags */
			uint8_t level:3; /* syslog level */
		} normal;
		struct {
			uint8_t level:3; /* syslog level */
			uint8_t flags:5; /* internal record flags */
		} swapped;
	} fl;
};

static size_t print_time(uint64_t ts)
{
	unsigned long rem_nsec;

	rem_nsec = ts / 1000000000;

	return printf("[%5lu.%06lu] ", (unsigned long)ts, rem_nsec / 1000);
}

static size_t print_prefix(const struct log *msg, unsigned int level)
{
	size_t len = 0;
	unsigned int prefix = (msg->facility << 3) | level;

	len += printf("<%u>", prefix);
	len += print_time(msg->ts_nsec);
	return len;
}

int main(int argc, char **argv)
{
	bool swap = false;
	unsigned int prev = 0;
	FILE *f = stdin;

	/* Use getopt !!! */
	argv++;
	argc--;
	while(argc) {
		if (!strcmp(argv[0], "--byteswap"))
			swap = 1;
		else if (!strcmp(argv[0], "--file") && (argc > 1)) {
			f = fopen(argv[1], "r");
			argv++;
			argc--;
		} else {
			printf("usage: kmsg_dump [--byteswap] [--file <path>]\n");
			exit(1);
		}
		argv++;
		argc--;
	}
	for (;;) {
		size_t sz;
		struct log l;
		unsigned int flags, level;
		uint8_t buf[0x10000];
		bool prefix = true;
		bool newline = true;
		const char *text;
		unsigned int text_size;

		sz = fread(&l, sizeof(struct log), 1, f);
		if (sz != 1)
			exit(0);
		if (swap) {
			l.ts_nsec = bswap_64(l.ts_nsec);
			l.len = bswap_16(l.len);
			l.text_len = bswap_16(l.text_len);
			l.dict_len = bswap_16(l.dict_len);
			flags = l.fl.swapped.flags;
			level = l.fl.swapped.level;
		} else {
			flags = l.fl.normal.flags;
			level = l.fl.normal.level;
		}

		if (l.len == 0)
			break;
		sz = fread(buf, l.len - sizeof(struct log), 1, f);
		if (sz != 1)
			break;
		
		if ((prev & LOG_CONT) && !(flags & LOG_PREFIX))
			prefix = false;

		if (flags & LOG_CONT) {
			if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
				prefix = false;

			if (!(flags & LOG_NEWLINE))
				newline = false;
		}

		text = buf;
		text_size = l.text_len;
		do {
			char *next = memchr(text, '\n', text_size);
			size_t text_len;

			if (next) {
				text_len = next - text;
				next++;
				text_size -= next - text;
			} else {
				text_len = text_size;
			}

			if (prefix)
				print_prefix(&l, level);
			fwrite(text, text_len, 1, stdout);
			if (next || newline)
				printf("\n");
			prefix = true;
			text = next;
		} while (text);
	}
	return 0;
}