/*
 * Copyright (c) 2015-2020 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

%option nounput
%option noinput
%option noyywrap
%option reentrant
%option bison-bridge
%option never-interactive

%{
#include <jeffpc/buffer.h>
#include <jeffpc/unicode.h>

#include "sexpr_impl.h"
#include "sexpr.tab.h"

extern void sexpr_error2(const char *e, const char *text);

#define YY_INPUT(buf, result, max_size)	\
	result = sexpr_reader_input_proc(buf, max_size, yyscanner)
static size_t sexpr_reader_input_proc(char *buf, size_t size, yyscan_t scanner);

static void inc_lineno(yyscan_t scanner);

static int getint(const char *str, uint64_t *i, int base, const char *type,
		  int okretval)
{
	int ret;

	ret = str2u64_base(str, i, base);
	if (ret) {
		char err[256];

		snprintf(err, sizeof(err), "base %d %s lexing error: %s",
			 base, type, xstrerror(ret));

		sexpr_error2(err, str);

		return ERROR;
	}

	return okretval;
}

static int getutf8(const char *str, size_t len, uint64_t *out)
{
	uint32_t tmp;
	int ret;

	ret = utf8_to_utf32(str, len, &tmp);
	if (ret != len)
		return ERROR;

	*out = tmp;

	return CHAR;
}
%}

%x string

%%
	struct buffer *buf = NULL;

\"			{
				BEGIN(string);

				buf = buffer_alloc(1000);
				ASSERT(!IS_ERR(buf));
			}
<string>\"		{
				ASSERT0(buffer_append_c(buf, '\0'));
				yylval->s = STR_DUP(buffer_data(buf));
				buffer_free(buf);
				BEGIN(INITIAL);
				return STRING;
			}
<string>[^\\"]*		{
				ASSERT0(buffer_append_cstr(buf, yytext));
			}
	/* TODO: handle octal escapes */
	/* TODO: handle hex escapes */
	/* TODO: handle unicode escapes */
<string>\\n		{ ASSERT0(buffer_append_c(buf, '\n')); }
<string>\\t		{ ASSERT0(buffer_append_c(buf, '\t')); }
<string>\\r		{ ASSERT0(buffer_append_c(buf, '\r')); }
<string>\\b		{ ASSERT0(buffer_append_c(buf, '\b')); }
<string>\\f		{ ASSERT0(buffer_append_c(buf, '\f')); }
<string>\\\\		{ ASSERT0(buffer_append_c(buf, '\\')); }
<string>\\\"		{ ASSERT0(buffer_append_c(buf, '"')); }
<string>\\u[0-9A-Fa-f]{4}	{
					char tmp[5];
					uint32_t cp;
					ssize_t len;
					int ret;

					ret = str2u32_base(yytext + 2, &cp, 16);
					if (ret)
						return ERROR;

					len = utf32_to_utf8(cp, tmp, sizeof(buf));
					if (len < 0)
						return ERROR;

					ASSERT0(buffer_append(buf, tmp, len));
				}

[().']			{ return *yytext; }
#[tf]			{ yylval->b = (yytext[1] == 't'); return BOOL; }
#n			{ return VNULL; }
0[0-7]*			{ return getint(yytext, &yylval->i, 8, "integer", NUMBER); }
0x[0-9a-fA-F]+		{ return getint(yytext, &yylval->i, 16, "integer", NUMBER); }
#x[0-9a-fA-F]+		{ return getint(yytext + 2, &yylval->i, 16, "integer", NUMBER); }
#\\u[0-9a-fA-F]+	{ return getint(yytext + 3, &yylval->i, 16, "character", CHAR); }

#\\nul			{ yylval->i = '\0'; return CHAR; }
#\\space		{ yylval->i = ' '; return CHAR; }

	/* #\<unicode char> */
#\\[\x00-\x7f]			{ return getutf8(yytext + 2, 1, &yylval->i); }
#\\[\x80-\xbf]			{ sexpr_error2("sexpr text contains illegal UTF-8 byte", yytext); yyterminate(); }
#\\[\xc0-\xdf][\x80-\xbf]	{ return getutf8(yytext + 2, 2, &yylval->i); }
#\\[\xe0-\xef][\x80-\xbf]{2}	{ return getutf8(yytext + 2, 3, &yylval->i); }
#\\[\xf0-\xf7][\x80-\xbf]{3}	{ return getutf8(yytext + 2, 4, &yylval->i); }
	/* TODO: handle #\<unicode char><combining char> */

[1-9][0-9]*		{ return getint(yytext, &yylval->i, 10, "integer", NUMBER); }
[a-zA-Z+=|&*?_-]?[a-zA-Z0-9+=|&*?_-]* { yylval->s = STR_DUP(yytext); return SYMBOL; }
[ \r\t]			{ /* ignore */ }
\n			{ inc_lineno(yyscanner); /* ignore */}
;[^\n]*			{ /* comment: ignore it */ }
.			{ sexpr_error2("sexp text contains invalid characters", yytext); yyterminate(); }
%%

static void inc_lineno(yyscan_t scanner)
{
	struct sexpr_parser_state *out;

	out = (struct sexpr_parser_state *) sexpr_reader_get_extra(scanner);

	out->lineno++;
}

static size_t sexpr_reader_input_proc(char *buf, size_t size, yyscan_t scanner)
{
	struct sexpr_parser_state *out;
	ssize_t num;

	out = (struct sexpr_parser_state *) sexpr_reader_get_extra(scanner);
	num = out->len - out->pos;

	if (num <= 0)
		return 0;

	num = MIN(num, size);

	memcpy(buf, out->input + out->pos, num);
	out->pos += num;

	return num;
}