#include "cache.h"
#include "commit.h"
#include "config.h"
#include "revision.h"
#include "argv-array.h"
#include "list-objects.h"
#include "list-objects-filter.h"
#include "list-objects-filter-options.h"
#include "trace.h"

static int parse_combine_filter(
	struct list_objects_filter_options *filter_options,
	const char *arg,
	struct strbuf *errbuf);

/*
 * Parse value of the argument to the "filter" keyword.
 * On the command line this looks like:
 *       --filter=<arg>
 * and in the pack protocol as:
 *       "filter" SP <arg>
 *
 * The filter keyword will be used by many commands.
 * See Documentation/rev-list-options.txt for allowed values for <arg>.
 *
 * Capture the given arg as the "filter_spec".  This can be forwarded to
 * subordinate commands when necessary (although it's better to pass it through
 * expand_list_objects_filter_spec() first).  We also "intern" the arg for the
 * convenience of the current command.
 */
static int gently_parse_list_objects_filter(
	struct list_objects_filter_options *filter_options,
	const char *arg,
	struct strbuf *errbuf)
{
	const char *v0;

	if (filter_options->choice)
		BUG("filter_options already populated");

	if (!strcmp(arg, "blob:none")) {
		filter_options->choice = LOFC_BLOB_NONE;
		return 0;

	} else if (skip_prefix(arg, "blob:limit=", &v0)) {
		if (git_parse_ulong(v0, &filter_options->blob_limit_value)) {
			filter_options->choice = LOFC_BLOB_LIMIT;
			return 0;
		}

	} else if (skip_prefix(arg, "tree:", &v0)) {
		if (!git_parse_ulong(v0, &filter_options->tree_exclude_depth)) {
			if (errbuf) {
				strbuf_addstr(
					errbuf,
					_("expected 'tree:<depth>'"));
			}
			return 1;
		}
		filter_options->choice = LOFC_TREE_DEPTH;
		return 0;

	} else if (skip_prefix(arg, "sparse:oid=", &v0)) {
		struct object_context oc;
		struct object_id sparse_oid;

		/*
		 * Try to parse <oid-expression> into an OID for the current
		 * command, but DO NOT complain if we don't have the blob or
		 * ref locally.
		 */
		if (!get_oid_with_context(the_repository, v0, GET_OID_BLOB,
					  &sparse_oid, &oc))
			filter_options->sparse_oid_value = oiddup(&sparse_oid);
		filter_options->choice = LOFC_SPARSE_OID;
		return 0;

	} else if (skip_prefix(arg, "sparse:path=", &v0)) {
		filter_options->choice = LOFC_SPARSE_PATH;
		filter_options->sparse_path_value = strdup(v0);
		return 0;

	} else if (skip_prefix(arg, "combine:", &v0)) {
		int sub_parse_res = parse_combine_filter(
			filter_options, v0, errbuf);
		if (sub_parse_res)
			return sub_parse_res;
		return 0;

	}
	/*
	 * Please update _git_fetch() in git-completion.bash when you
	 * add new filters
	 */

	if (errbuf)
		strbuf_addf(errbuf, _("invalid filter-spec '%s'"), arg);

	memset(filter_options, 0, sizeof(*filter_options));
	return 1;
}

static int digit_value(int c, struct strbuf *errbuf) {
	if (c >= '0' && c <= '9')
		return c - '0';
	if (c >= 'a' && c <= 'f')
		return c - 'a' + 10;
	if (c >= 'A' && c <= 'F')
		return c - 'A' + 10;

	if (!errbuf)
		return -1;

	strbuf_addf(errbuf, _("error in filter-spec - "));
	if (c)
		strbuf_addf(
			errbuf,
			_("expect two hex digits after %%, but got: '%c'"),
			c);
	else
		strbuf_addf(
			errbuf,
			_("not enough hex digits after %%; expected two"));

	return -1;
}

static int url_decode(struct strbuf *s, struct strbuf *errbuf) {
	char *dest = s->buf;
	char *src = s->buf;
	size_t new_len;

	while (*src) {
		int digit_value_0, digit_value_1;

		if (src[0] != '%') {
			*dest++ = *src++;
			continue;
		}
		src++;

		digit_value_0 = digit_value(*src++, errbuf);
		if (digit_value_0 < 0)
			return 1;
		digit_value_1 = digit_value(*src++, errbuf);
		if (digit_value_1 < 0)
			return 1;
		*dest++ = digit_value_0 * 16 + digit_value_1;
	}
	new_len = dest - s->buf;
	strbuf_remove(s, new_len, s->len - new_len);

	return 0;
}

static const char *RESERVED_NON_WS = "~`!@#$^&*()[]{}\\;'\",<>?";

static int has_reserved_character(
	struct strbuf *sub_spec, struct strbuf *errbuf)
{
	const char *c = sub_spec->buf;
	while (*c) {
		if (*c <= ' ' || strchr(RESERVED_NON_WS, *c))
			goto found_reserved;
		c++;
	}

	return 0;

found_reserved:
	if (errbuf)
		strbuf_addf(errbuf,
			    "must escape char in sub-filter-spec: '%c'",
			    *c);
	return 1;
}

static int parse_combine_filter(
	struct list_objects_filter_options *filter_options,
	const char *arg,
	struct strbuf *errbuf)
{
	struct strbuf **sub_specs = strbuf_split_str(arg, '+', 2);
	int result;

	if (!sub_specs[0]) {
		if (errbuf)
			strbuf_addf(errbuf,
				    _("expected something after combine:"));
		result = 1;
		goto cleanup;
	}

	result = has_reserved_character(sub_specs[0], errbuf);
	if (result)
		goto cleanup;

	/*
	 * Only decode the first sub-filter, since the rest will be decoded on
	 * the recursive call.
	 */
	result = url_decode(sub_specs[0], errbuf);
	if (result)
		goto cleanup;

	if (!sub_specs[1]) {
		/*
		 * There is only one sub-filter, so we don't need the
		 * combine: - just parse it as a non-composite filter.
		 */
		result = gently_parse_list_objects_filter(
			filter_options, sub_specs[0]->buf, errbuf);
		goto cleanup;
	}

	/* Remove trailing "+" so we can parse it. */
	assert(sub_specs[0]->buf[sub_specs[0]->len - 1] == '+');
	strbuf_remove(sub_specs[0], sub_specs[0]->len - 1, 1);

	filter_options->choice = LOFC_COMBINE;
	filter_options->lhs = xcalloc(1, sizeof(*filter_options->lhs));
	filter_options->rhs = xcalloc(1, sizeof(*filter_options->rhs));

	result = gently_parse_list_objects_filter(filter_options->lhs,
						  sub_specs[0]->buf,
						  errbuf) ||
		parse_combine_filter(filter_options->rhs,
				      sub_specs[1]->buf,
				      errbuf);

cleanup:
	strbuf_list_free(sub_specs);
	if (result) {
		list_objects_filter_release(filter_options);
		memset(filter_options, 0, sizeof(*filter_options));
	}
	return result;
}

static void add_url_encoded(struct strbuf *dest, const char *s)
{
	while (*s) {
		if (*s <= ' ' || strchr(RESERVED_NON_WS, *s) ||
			*s == '%' || *s == '+')
			strbuf_addf(dest, "%%%02X", (int)*s);
		else
			strbuf_addf(dest, "%c", *s);
		s++;
	}
}

/*
 * Returns a new filter-spec string by combining (with combine:) the two
 * sub-specs. The caller gains ownership of a new string, and lhs and rhs are
 * not freed.
 */
static char *combine_specs(const char *lhs, const char *rhs)
{
	struct strbuf combined = STRBUF_INIT;
	if (starts_with(lhs, "combine:")) {
		strbuf_addf(&combined, "%s", lhs);
	} else {
		strbuf_addf(&combined, "combine:");
		add_url_encoded(&combined, lhs);
	}
	strbuf_addf(&combined, "+");

	add_url_encoded(&combined, rhs);
	trace_printf("Generated composite filter-spec: %s\n", combined.buf);
	return strbuf_detach(&combined, NULL);
}

int parse_list_objects_filter(
	struct list_objects_filter_options *filter_options,
	const char *arg,
	int allow_implicit_combine)
{
	struct strbuf errbuf = STRBUF_INIT;
	if (filter_options->choice) {
		struct list_objects_filter_options *lhs;

		if (!allow_implicit_combine)
			die(_("multiple filter-specs cannot be combined"));

		lhs = xcalloc(1, sizeof(*lhs));
		*lhs = *filter_options;
		memset(filter_options, 0, sizeof(*filter_options));

		filter_options->lhs = lhs;
		filter_options->rhs = xcalloc(1, sizeof(*filter_options->rhs));
		filter_options->choice = LOFC_COMBINE;

		/*
		 * Build up the filter-spec string using the already-parsed
		 * portion (the lhs) and the to-be-parsed portion (the rhs).
		 */
		filter_options->filter_spec = combine_specs(
			lhs->filter_spec, arg);
		FREE_AND_NULL(lhs->filter_spec);

		/*
		 * The gentle parse function below will populate the rhs of the
		 * combined filter. But the caller of *this* function sees
		 * filter_options as the combined filter.
		 */
		filter_options = filter_options->rhs;
	} else {
		filter_options->filter_spec = strdup(arg);
	}
	if (gently_parse_list_objects_filter(filter_options, arg, &errbuf))
		die("%s", errbuf.buf);
	return 0;
}

int opt_parse_list_objects_filter(const struct option *opt,
				  const char *arg, int unset)
{
	struct list_objects_filter_options *filter_options = opt->value;

	if (unset || !arg) {
		list_objects_filter_set_no_filter(filter_options);
		return 0;
	}

	return parse_list_objects_filter(
		filter_options, arg, /*allow_implicit_combine=*/1);
}

void expand_list_objects_filter_spec(
	const struct list_objects_filter_options *filter,
	struct strbuf *expanded_spec)
{
	strbuf_init(expanded_spec, strlen(filter->filter_spec));
	if (filter->choice == LOFC_BLOB_LIMIT)
		strbuf_addf(expanded_spec, "blob:limit=%lu",
			    filter->blob_limit_value);
	else if (filter->choice == LOFC_TREE_DEPTH)
		strbuf_addf(expanded_spec, "tree:%lu",
			    filter->tree_exclude_depth);
	else
		strbuf_addstr(expanded_spec, filter->filter_spec);
}

void list_objects_filter_release(
	struct list_objects_filter_options *filter_options)
{
	if (!filter_options)
		return;
	free(filter_options->filter_spec);
	free(filter_options->sparse_oid_value);
	free(filter_options->sparse_path_value);
	list_objects_filter_release(filter_options->lhs);
	free(filter_options->lhs);
	list_objects_filter_release(filter_options->rhs);
	free(filter_options->rhs);
	memset(filter_options, 0, sizeof(*filter_options));
}

void partial_clone_register(
	const char *remote,
	const struct list_objects_filter_options *filter_options)
{
	/*
	 * Record the name of the partial clone remote in the
	 * config and in the global variable -- the latter is
	 * used throughout to indicate that partial clone is
	 * enabled and to expect missing objects.
	 */
	if (repository_format_partial_clone &&
	    *repository_format_partial_clone &&
	    strcmp(remote, repository_format_partial_clone))
		die(_("cannot change partial clone promisor remote"));

	git_config_set("core.repositoryformatversion", "1");
	git_config_set("extensions.partialclone", remote);

	repository_format_partial_clone = xstrdup(remote);

	/*
	 * Record the initial filter-spec in the config as
	 * the default for subsequent fetches from this remote.
	 */
	core_partial_clone_filter_default =
		xstrdup(filter_options->filter_spec);
	git_config_set("core.partialclonefilter",
		       core_partial_clone_filter_default);
}

void partial_clone_get_default_filter_spec(
	struct list_objects_filter_options *filter_options)
{
	/*
	 * Parse default value, but silently ignore it if it is invalid.
	 */
	if (!core_partial_clone_filter_default)
		return;

	filter_options->filter_spec = strdup(core_partial_clone_filter_default);
	gently_parse_list_objects_filter(filter_options,
					 core_partial_clone_filter_default,
					 NULL);
}