/*
 * Copyright (c) 2026 Nakidai Perumenei <nakidai at disroot dot org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "thac.h"

#include <ctype.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>


static struct tok storage;
struct tok curtok;
static int isunget;
ulong curline;

static int
isidish(int ch)
{
	static char lut[256] = {
		['a'] = 1, ['b'] = 1, ['c'] = 1, ['d'] = 1, ['e'] = 1, ['f'] = 1,
		['g'] = 1, ['h'] = 1, ['i'] = 1, ['j'] = 1, ['k'] = 1, ['l'] = 1,
		['m'] = 1, ['n'] = 1, ['o'] = 1, ['p'] = 1, ['q'] = 1, ['r'] = 1,
		['s'] = 1, ['t'] = 1, ['u'] = 1, ['v'] = 1, ['w'] = 1, ['x'] = 1,
		['y'] = 1, ['z'] = 1, ['A'] = 1, ['B'] = 1, ['C'] = 1, ['D'] = 1,
		['E'] = 1, ['F'] = 1, ['G'] = 1, ['H'] = 1, ['I'] = 1, ['J'] = 1,
		['K'] = 1, ['L'] = 1, ['M'] = 1, ['N'] = 1, ['O'] = 1, ['P'] = 1,
		['Q'] = 1, ['R'] = 1, ['S'] = 1, ['T'] = 1, ['U'] = 1, ['V'] = 1,
		['W'] = 1, ['X'] = 1, ['Y'] = 1, ['Z'] = 1, ['@'] = 1, ['_'] = 1,
		['0'] = 1, ['1'] = 1, ['2'] = 1, ['3'] = 1, ['4'] = 1, ['5'] = 1,
		['6'] = 1, ['7'] = 1, ['8'] = 1, ['9'] = 1, ['\''] = 1,
	};

	if (ch < 0 || ch > 255)
		return 0;

	return lut[ch];
}

static void
append(int ch)
{
	if (curtok.info.cap < curtok.info.len + 1)
		curtok.info.p = realloc(
			curtok.info.p,
			curtok.info.cap = (curtok.info.cap + sizeof(*curtok.info.p)) * 2
		);
	if (!curtok.info.p)
		dieno(1, "realloc()");
	curtok.info.p[curtok.info.len++] = ch;
}

static int
get(void)
{
	int ch;

	if ((ch = getc(curfile)) == EOF)
		return -1;
	append(ch);

	curline += (ch == '\n');

	return ch;
}

static int
unget(int ch)
{
	--curtok.info.len;
	curline -= (ch == '\n');
	return ungetc(ch, curfile);
}

void
word(void)
{
	char *s;
	int ch;

	while ((ch = get()) != EOF)
		if (!isidish(ch))
			break;
	if (ch != EOF)
		unget(ch);
	append('\0');

	s = curtok.info.p;

	curtok.type = TID;
#define is(wanted) !strcmp(s, (wanted))
	curtok.type = isdigit(*s)    ? TNUM :
	              is("assert")   ? TKEYASSERT :
	              is("if")       ? TKEYIF :
	              is("else")     ? TKEYELSE :
	              is("for")      ? TKEYFOR :
	              is("foreach")  ? TKEYFOREACH :
	              is("len")      ? TKEYLEN :
	              is("mod")      ? TKEYMOD :
	              is("node")     ? TKEYNODE :
	              is("with")     ? TKEYWITH :
	              is("break")    ? TKEYBREAK :
	              is("continue") ? TKEYCONT :
		               TID;
#undef is

	return;
}

void
oper(void)
{
	int ch;

	switch (ch = get())
	{
	/* these are not start of any other operator */
#define SINGLE(ch, t) case (ch): curtok.type = (t); append('\0'); return
	SINGLE('{', TOPBRACE);
	SINGLE('}', TCLBRACE);
	SINGLE('[', TOPBRACK);
	SINGLE(']', TCLBRACK);
	SINGLE('(', TOPPAREN);
	SINGLE(')', TCLPAREN);
	SINGLE(':', TCOL);
	SINGLE(',', TCOMMA);
	SINGLE('?', TQUEST);
	SINGLE(';', TSEMICOL);
	SINGLE('~', TTILDE);
#undef SINGLE
	/*
	 * these are cases when operator is one of:
	 * t1  = {ch1}
	 * t21 = {ch1}{ch21}
	 * t22 = {ch1}{ch22}
	 */
#define DOUBLE(ch1, ch21, ch22, t1, t21, t22) case (ch1): \
{ \
	int next; \
	curtok.type = (t1); \
	if ((next = get()) == EOF) \
		(void)0; \
	else if (next == (ch21)) \
		curtok.type = (t21); \
	else if (next == (ch22)) \
		curtok.type = (t22); \
	else \
		unget(next); \
	append('\0'); \
	return; \
}
	DOUBLE('&', '=', '&', TAMPER, TASSAMPER, TAND);
	DOUBLE('^', '=', EOF, TCARET, TASSCARET, 0);
	DOUBLE('=', '=', EOF, TASSIGN, TEQ, 0);
	DOUBLE('|', '=', '|', TPIPE, TASSPIPE, TOR);
	DOUBLE('/', '=', EOF, TSLASH, TASSSLASH, 0);
	DOUBLE('%', '=', EOF, TPERC, TASSPERC, 0);
	DOUBLE('!', '=', EOF, TEXCLAM, TNEQ, 0);
	DOUBLE('-', '=', '-', TMINUS, TASSMINUS, TDECR);
	DOUBLE('+', '=', '+', TPLUS, TASSPLUS, TINCR);
	DOUBLE('*', '=', '*', TASTER, TASSASTER, TPOW);
#undef DOUBLE
	/*
	 * these are cases when operator is one of:
	 * t1  = {ch1}
	 * t21 = {ch1}{ch21}
	 * t22 = {ch1}{ch22}
	 * t23 = {ch1}{ch1}
	 * t3  = {ch1}{ch1}{ch3}
	 */
#define TRIPLE(ch1, ch21, ch22, ch3, t1, t21, t22, t23, t3) case (ch1): \
{ \
	int next; \
	curtok.type = (t1); \
	if ((next = get()) == EOF) \
		(void)0; \
	else if (next == (ch21)) \
		curtok.type = (t21); \
	else if (next == (ch22)) \
		curtok.type = (t22); \
	else if (next == ch) \
	{ \
		curtok.type = (t23); \
		if ((next = get()) == EOF) \
			(void)0; \
		else if (next == (ch3)) \
			curtok.type = (t3); \
		else \
			unget(next); \
	} \
	else \
		unget(next); \
	append('\0'); \
	return; \
}
	TRIPLE('>', '=', '<', '=', TGREAT, TGREATEQ, TCONCAT, TRSHIFT, TASSRSHIFT);
	TRIPLE('<', '=', '-', '=', TLESS, TLESSEQ, TARRLEFT, TLSHIFT, TASSLSHIFT);
#undef TRIPLE
	}

	complain(1, "unknown operator starting with %c", ch);
}

enum tok_t
gettok(void)
{
	int ch;

	curtok.info = (struct tinfo){NULL, 0, 0};

	if (isunget)
	{
		isunget = 0;
		curtok = storage;
		/*say("reread %s(`%s')", tokname(curtok.type), curtok.info.p)*/;
		return curtok.type;
	}

	for (; (ch = get()) != EOF; curtok.info.len = 0)
		if (!isspace(ch))
			goto found;
	return curtok.type = TEOF;
found:
	unget(ch);

	if (isidish(ch))
		word();
	else
		oper();

	/*say("read %s(`%s')", tokname(curtok.type), curtok.info.p)*/;
	return curtok.type;
}

void
ungettok()
{
	storage = curtok;
	isunget = 1;
}

int
_exptok(enum tok_t first, ...)
{
	enum tok_t next;
	va_list ap;
	int res;

	if (gettok() == TEOF)
		return 0;
	if (curtok.type == first)
		return 1;

	res = 0;
	va_start(ap, first);
	while ((next = va_arg(ap, enum tok_t)) != TEOF)
		if (curtok.type == next)
		{
			res = 1;
			break;
		}
	va_end(ap);

	return res;
}