#include <config.h>
#include <stdio.h>
#include <assert.h>

#include "typemap.h"
#include "output.h"
#include "cdecl.h"

size_t cdecl__advance_(char **buf, size_t *n, size_t amount)
{
	if (amount >= *n) {
		*n   = 0;
		*buf = 0;
	} else {
		*buf += amount;
		*n   -= amount;
	}

	return amount;
}

size_t cdecl__advance(char **buf, size_t *n, size_t amount)
{
	size_t ret, rc;

	if (!amount)
		return 0;

	ret = cdecl__advance_(buf, n, amount);
	rc = snprintf(*buf, *n, " ");
	return ret + cdecl__advance_(buf, n, rc);
}

static size_t explain_storage(char *buf, size_t n, unsigned spec)
{
	switch (spec) {
	case CDECL_STOR_TYPEDEF:
		return snprintf(buf, n, "typedef");
	case CDECL_STOR_EXTERN:
		return snprintf(buf, n, "extern");
	case CDECL_STOR_STATIC:
		return snprintf(buf, n, "static");
	case CDECL_STOR_AUTO:
		return snprintf(buf, n, "auto");
	case CDECL_STOR_REGISTER:
		return snprintf(buf, n, "register");
	default:
		assert(0);
	}
}

/* Renders the storage-class and function specifiers in canonical form. */
size_t cdecl__explain_pre_specs(char *buf, size_t n, struct cdecl_declspec *s)
{
	unsigned long funcmap = 0;
	size_t ret = 0, rc = 0;

	for (struct cdecl_declspec *c = s; c; c = c->next) {
		switch (cdecl_spec_kind(c)) {
		case CDECL_SPEC_FUNC:
			funcmap |= 1ul << (c->type & 0xff);
			break;
		case CDECL_SPEC_STOR:
			/* Valid C declarations have at most one
			 * storage-class specifier. */
			rc = explain_storage(buf, n, c->type);
			break;
		}
	}

	if (funcmap & (1ul << (CDECL_FUNC_INLINE & 0xff))) {
		ret += cdecl__advance(&buf, &n, rc);
		rc = snprintf(buf, n, "inline");
	}

	return ret + rc;
}

size_t cdecl__explain_qualifiers(char *buf, size_t n, struct cdecl_declspec *s)
{
	unsigned long qualmap = 0;
	size_t ret = 0, rc = 0;

	for (struct cdecl_declspec *c = s; c; c = c->next) {
		if (cdecl_spec_kind(c) != CDECL_SPEC_QUAL)
			continue;
		qualmap |= 1ul << (c->type & 0xff);
	}

	if (qualmap & (1ul << (CDECL_QUAL_RESTRICT & 0xff))) {
		ret += cdecl__advance(&buf, &n, rc);
		rc = snprintf(buf, n, "restrict");
	}
	if (qualmap & (1ul << (CDECL_QUAL_VOLATILE & 0xff))) {
		ret += cdecl__advance(&buf, &n, rc);
		rc = snprintf(buf, n, "volatile");
	}
	if (qualmap & (1ul << (CDECL_QUAL_CONST & 0xff))) {
		ret += cdecl__advance(&buf, &n, rc);
		rc = snprintf(buf, n, "const");
	}

	return ret + rc;
}

/* Renders the type qualifiers and type specifiers in canonical form. */
size_t cdecl__explain_post_specs(char *buf, size_t n, struct cdecl_declspec *s)
{
	const char *tag = NULL;
	unsigned long typemap;
	size_t ret = 0, rc;

	typemap = cdecl__build_typemap(s);
	if (typemap == -1)
		return 0;

	for (struct cdecl_declspec *c = s; c; c = c->next) {
		if (cdecl_spec_kind(c) != CDECL_SPEC_TYPE)
			continue;

		/* Valid C types have at most one identifier. */
		if (c->ident)
			tag = c->ident;
	}

	rc = cdecl__explain_qualifiers(buf, n, s);
	ret += cdecl__advance(&buf, &n, rc);

	rc = snprintf(buf, n, "%s", cdecl__explain_typemap(typemap));
	if (tag) {
		ret += cdecl__advance(&buf, &n, rc);
		rc = snprintf(buf, n, "%s", tag);
	}

	return ret + rc;
}