/* Simple program to search for BOLT references in C files and make sure
 * they're accurate. */
#include "config.h"
#include <ccan/err/err.h>
#include <ccan/opt/opt.h>
#include <ccan/tal/grab_file/grab_file.h>
#include <ccan/tal/path/path.h>
#include <ccan/tal/str/str.h>
#include <common/utils.h>
#include <dirent.h>

static bool verbose = false;

struct bolt_file {
	const char *prefix;
	const char *contents;
};

/* Turn any whitespace into a single space. */
static char *canonicalize(char *str)
{
	char *to = str, *from = str;
	bool have_space = true;

	while (*from) {
		if (cisspace(*from)) {
			if (!have_space)
				*(to++) = ' ';
			have_space = true;
		} else {
			*(to++) = *from;
			have_space = false;
		}
		from++;
	}
	if (have_space && to != str)
		to--;
	*to = '\0';
	tal_resize(&str, to + 1 - str);
	return str;
}

static bool get_files(const char *dir, const char *subdir,
		      struct bolt_file **files)
{
	char *path = path_join(NULL, dir, subdir);
	DIR *d = opendir(path);
	struct dirent *e;

	if (!d)
		return false;

	while ((e = readdir(d)) != NULL) {
		int preflen;
		struct bolt_file bf;

		/* Must end in .md */
		if (!strends(e->d_name, ".md"))
			continue;

		/* Prefix is anything up to - */
		preflen = strspn(e->d_name,
				 "0123456789"
				 "abcdefghijklmnopqrstuvwxyz"
				 "ABCDEFGHIJKLMNOPQRSTUVWXYZ");
		if (!preflen)
			continue;
		if (preflen + strlen(".md") != strlen(e->d_name)
		    && e->d_name[preflen] != '-')
			continue;

		if (verbose)
			printf("Found bolt %.*s\n", preflen, e->d_name);

		bf.prefix = tal_strndup(*files, e->d_name, preflen);
		bf.contents
			= canonicalize(grab_file(*files,
						 path_join(path, path,
							   e->d_name)));
		tal_arr_expand(files, bf);
	}
	closedir(d);
	return true;
}

static struct bolt_file *get_bolt_files(const char *dir)
{
	struct bolt_file *bolts = tal_arr(NULL, struct bolt_file, 0);

	if (!get_files(dir, ".", &bolts))
		err(1, "Opening BOLT dir %s", dir);
	/* This currently does not exist. */
	get_files(dir, "early-drafts", &bolts);
	return bolts;
}

static char *find_bolt_ref(const char *prefix, char **p, size_t *len)
{
	for (;;) {
		char *bolt, *end;
		size_t preflen;

		/* Quote is of form 'BOLT #X:' */
		*p = strchr(*p, '*');
		if (!*p)
			return NULL;
		*p += 1;
		while (cisspace(**p))
			(*p)++;
		if (strncmp(*p, prefix, strlen(prefix)) != 0)
			continue;
		*p += strlen(prefix);
		while (cisspace(**p))
			(*p)++;
		if (**p != '#')
			continue;
		(*p)++;

		preflen = strcspn(*p, " :");
		bolt = tal_strndup(NULL, *p, preflen);

		(*p) += preflen;
		while (cisspace(**p))
			(*p)++;
		if (**p != ':')
			continue;
		(*p)++;

		end = strstr(*p, "*/");
		if (!end)
			*len = strlen(*p);
		else
			*len = end - *p;
		return bolt;
	}
}

/* Replace '*' at start of line with whitespace, canonicalize */
static char *de_prefix(char *str)
{
	bool start_of_line = true;
	size_t i;

	for (i = 0; str[i]; i++) {
		if (start_of_line && str[i] == '*') {
			str[i] = ' ';
			start_of_line = false;
		}

		/* Stay start of line until whitespace ends */
		if (start_of_line)
			start_of_line = cisspace(str[i]);
		else
			start_of_line = (str[i] == '\n');
	}

	return canonicalize(str);
}

/* Take a quote, split it on '...' (trim line prefixes) */
static char **split_pattern(const char *code, size_t len)
{
	char **strings = tal_arr(NULL, char *, 0);
	const char *sep;

	while ((sep = strstr(code, "...")) != NULL) {
		size_t matchlen = sep - code;
		if (sep > code + len)
			break;
		tal_arr_expand(&strings,
			       de_prefix(tal_strndup(strings, code, matchlen)));
		code += matchlen + strlen("...");
		len -= matchlen + strlen("...");
	}

	tal_arr_expand(&strings, de_prefix(tal_strndup(strings, code, len)));
	return strings;
}

/* Moves *pos to start of line. */
static unsigned linenum(const char *raw, const char **pos)
{
	unsigned line = 0; /* Out-by-one below */
	const char *l = raw, *point = *pos;

	while (l < point) {
		*pos = l;
		l = strchr(l, '\n');
		line++;
		if (!l)
			break;
		l++;
	}
	return line;
}

static void fail_mismatch(const char *filename,
			  const char *raw,
			  const char *pos,
			  size_t len,
			  char **strings,
			  struct bolt_file *bolt)
{
	unsigned line = linenum(raw, &pos);
	/* If they all match, order must be wrong. */
	const char *match = NULL;
	int matchlen;

	/* Figure out which substring didn't match, and how much to cut it */
	for (size_t i = 0; i < tal_count(strings); i++) {
		if (strstr(bolt->contents, strings[i]))
			continue;

		/* OK, it doesn't match, truncate it until it does */
		matchlen = strlen(strings[i]);
		while (matchlen) {
			match = memmem(bolt->contents, strlen(bolt->contents),
				       strings[i], matchlen);
			if (match)
				break;
			matchlen--;
		}
		break;
	}

	fprintf(stderr, "%s:%u:", filename, line);
	if (match) {
		fprintf(stderr, "Closest match: %.*s...[%.20s]\n",
			matchlen, match, match + matchlen);
	} else {
		fprintf(stderr, "Parts match, but not in this order\n");
	}
	exit(1);
}

static bool find_strings(const char *bolttext, char **strings, size_t nstrings)
{
	const char *p = bolttext;
	char *find;

	if (nstrings == 0)
		return true;

	while ((find = strstr(p, strings[0])) != NULL) {
		if (find_strings(find + strlen(strings[0]), strings+1, nstrings-1))
			return true;
		p = find + 1;
	}
	return false;
}

static void fail_nobolt(const char *filename,
			const char *raw, const char *pos,
			const char *bolt_prefix)
{
	unsigned line = linenum(raw, &pos);

	fprintf(stderr, "%s:%u:unknown bolt %s\n",
		filename, line, bolt_prefix);
	exit(1);
}

static struct bolt_file *find_bolt(const char *bolt_prefix,
				   struct bolt_file *bolts)
{
	size_t i, n = tal_count(bolts);
	int boltnum;
	char *endp;

	for (i = 0; i < n; i++)
		if (streq(bolts[i].prefix, bolt_prefix))
			return bolts+i;

	/* Now search for numerical match. */
	boltnum = strtol(bolt_prefix, &endp, 10);
	if (endp != bolt_prefix && *endp == 0) {
		for (i = 0; i < n; i++)
			if (atoi(bolts[i].prefix) == boltnum)
				return bolts+i;
	}

	return NULL;
}

int main(int argc, char *argv[])
{
	setup_locale();

	struct bolt_file *bolts;
	int i;
	char *prefix = "BOLT";

	err_set_progname(argv[0]);

	opt_register_noarg("--help|-h", opt_usage_and_exit,
			   "<bolt-dir> <srcfile>...\n"
			   "A source checker for BOLT RFC references.",
			   "Print this message.");
	opt_register_noarg("--verbose", opt_set_bool, &verbose,
			   "Print out files as we find them");
	opt_register_arg("--prefix", opt_set_charp, opt_show_charp, &prefix,
			 "Only check these markers");

	opt_parse(&argc, argv, opt_log_stderr_exit);
	if (argc < 2)
		opt_usage_exit_fail("Expected a bolt directory");

	bolts = get_bolt_files(argv[1]);

	for (i = 2; i < argc; i++) {
		char *f = grab_file(NULL, argv[i]), *p, *bolt;
		size_t len;
		if (!f)
			err(1, "Loading %s", argv[i]);

		if (verbose)
			printf("Checking %s...\n", argv[i]);

		p = f;
		while ((bolt = find_bolt_ref(prefix, &p, &len)) != NULL) {
			char **strings = split_pattern(p, len);
			struct bolt_file *b = find_bolt(bolt, bolts);
			if (!b)
				fail_nobolt(argv[i], f, p, bolt);

			if (!find_strings(b->contents, strings, tal_count(strings)))
				fail_mismatch(argv[i], f, p, len, strings, b);

			if (verbose)
				printf("  Found %.10s... in %s\n",
				       p, b->prefix);
			p += len;
		}
		tal_free(f);
	}
	return 0;
}