/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8   -*-│
│vi: set et ft=c ts=8 tw=8 fenc=utf-8                                       :vi│
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│ Copyright (C) Lucent Technologies 1997                                       │
│ All Rights Reserved                                                          │
│                                                                              │
│ Permission to use, copy, modify, and distribute this software and            │
│ its documentation for any purpose and without fee is hereby                  │
│ granted, provided that the above copyright notice appear in all              │
│ copies and that both that the copyright notice and this                      │
│ permission notice and warranty disclaimer appear in supporting               │
│ documentation, and that the name Lucent Technologies or any of               │
│ its entities not be used in advertising or publicity pertaining              │
│ to distribution of the software without specific, written prior              │
│ permission.                                                                  │
│                                                                              │
│ LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,                │
│ INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.             │
│ IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY            │
│ SPECIAL, 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 "libc/calls/calls.h"
#include "libc/fmt/conv.h"
#include "libc/fmt/fmt.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "third_party/awk/awk.h"
#include "third_party/awk/awkgram.tab.h"
#include "third_party/gdtoa/gdtoa.h"
// clang-format off

extern bool	infunc;

int	lineno	= 1;
int	bracecnt = 0;
int	brackcnt  = 0;
int	parencnt = 0;

typedef struct Keyword {
	const char *word;
	int	sub;
	int	type;
} Keyword;

const Keyword keywords[] = {	/* keep sorted: binary searched */
	{ "BEGIN",	XBEGIN,		XBEGIN },
	{ "END",	XEND,		XEND },
	{ "NF",		VARNF,		VARNF },
	{ "atan2",	FATAN,		BLTIN },
	{ "break",	BREAK,		BREAK },
	{ "close",	CLOSE,		CLOSE },
	{ "continue",	CONTINUE,	CONTINUE },
	{ "cos",	FCOS,		BLTIN },
	{ "delete",	DELETE,		DELETE },
	{ "do",		DO,		DO },
	{ "else",	ELSE,		ELSE },
	{ "exit",	EXIT,		EXIT },
	{ "exp",	FEXP,		BLTIN },
	{ "fflush",	FFLUSH,		BLTIN },
	{ "for",	FOR,		FOR },
	{ "func",	FUNC,		FUNC },
	{ "function",	FUNC,		FUNC },
	{ "getline",	GETLINE,	GETLINE },
	{ "gsub",	GSUB,		GSUB },
	{ "if",		IF,		IF },
	{ "in",		IN,		IN },
	{ "index",	INDEX,		INDEX },
	{ "int",	FINT,		BLTIN },
	{ "length",	FLENGTH,	BLTIN },
	{ "log",	FLOG,		BLTIN },
	{ "match",	MATCHFCN,	MATCHFCN },
	{ "next",	NEXT,		NEXT },
	{ "nextfile",	NEXTFILE,	NEXTFILE },
	{ "print",	PRINT,		PRINT },
	{ "printf",	PRINTF,		PRINTF },
	{ "rand",	FRAND,		BLTIN },
	{ "return",	RETURN,		RETURN },
	{ "sin",	FSIN,		BLTIN },
	{ "split",	SPLIT,		SPLIT },
	{ "sprintf",	SPRINTF,	SPRINTF },
	{ "sqrt",	FSQRT,		BLTIN },
	{ "srand",	FSRAND,		BLTIN },
	{ "sub",	SUB,		SUB },
	{ "substr",	SUBSTR,		SUBSTR },
	{ "system",	FSYSTEM,	BLTIN },
	{ "tolower",	FTOLOWER,	BLTIN },
	{ "toupper",	FTOUPPER,	BLTIN },
	{ "while",	WHILE,		WHILE },
};

#define	RET(x)	{ if(dbg)printf("lex %s\n", tokname(x)); return(x); }

static int peek(void)
{
	int c = input();
	unput(c);
	return c;
}

static int gettok(char **pbuf, int *psz)	/* get next input token */
{
	int c, retc;
	char *buf = *pbuf;
	int sz = *psz;
	char *bp = buf;

	c = input();
	if (c == 0)
		return 0;
	buf[0] = c;
	buf[1] = 0;
	if (!isalnum(c) && c != '.' && c != '_')
		return c;

	*bp++ = c;
	if (isalpha(c) || c == '_') {	/* it's a varname */
		for ( ; (c = input()) != 0; ) {
			if (bp-buf >= sz)
				if (!adjbuf(&buf, &sz, bp-buf+2, 100, &bp, "gettok"))
					FATAL( "out of space for name %.10s...", buf );
			if (isalnum(c) || c == '_')
				*bp++ = c;
			else {
				*bp = 0;
				unput(c);
				break;
			}
		}
		*bp = 0;
		retc = 'a';	/* alphanumeric */
	} else {	/* maybe it's a number, but could be . */
		char *rem;
		/* read input until can't be a number */
		for ( ; (c = input()) != 0; ) {
			if (bp-buf >= sz)
				if (!adjbuf(&buf, &sz, bp-buf+2, 100, &bp, "gettok"))
					FATAL( "out of space for number %.10s...", buf );
			if (isdigit(c) || c == 'e' || c == 'E'
			  || c == '.' || c == '+' || c == '-')
				*bp++ = c;
			else {
				unput(c);
				break;
			}
		}
		*bp = 0;
		strtod(buf, &rem);	/* parse the number */
		if (rem == buf) {	/* it wasn't a valid number at all */
			buf[1] = 0;	/* return one character as token */
			retc = (uschar)buf[0];	/* character is its own type */
			unputstr(rem+1); /* put rest back for later */
		} else {	/* some prefix was a number */
			unputstr(rem);	/* put rest back for later */
			rem[0] = 0;	/* truncate buf after number part */
			retc = '0';	/* type is number */
		}
	}
	*pbuf = buf;
	*psz = sz;
	return retc;
}

int	word(char *);
int	string(void);
int	regexpr(void);
bool	sc	= false;	/* true => return a } right now */
bool	reg	= false;	/* true => return a REGEXPR now */

int yylex(void)
{
	int c;
	static char *buf = NULL;
	static int bufsize = 5; /* BUG: setting this small causes core dump! */

	if (buf == NULL && (buf = (char *) malloc(bufsize)) == NULL)
		FATAL( "out of space in yylex" );
	if (sc) {
		sc = false;
		RET('}');
	}
	if (reg) {
		reg = false;
		return regexpr();
	}
	for (;;) {
		c = gettok(&buf, &bufsize);
		if (c == 0)
			return 0;
		if (isalpha(c) || c == '_')
			return word(buf);
		if (isdigit(c)) {
			char *cp = tostring(buf);
			double result;

			if (is_number(cp, & result))
				yylval.cp = setsymtab(buf, cp, result, CON|NUM, symtab);
			else
				yylval.cp = setsymtab(buf, cp, 0.0, STR, symtab);
			free(cp);
			/* should this also have STR set? */
			RET(NUMBER);
		}

		yylval.i = c;
		switch (c) {
		case '\n':	/* {EOL} */
			lineno++;
			RET(NL);
		case '\r':	/* assume \n is coming */
		case ' ':	/* {WS}+ */
		case '\t':
			break;
		case '#':	/* #.* strip comments */
			while ((c = input()) != '\n' && c != 0)
				;
			unput(c);
			/*
			 * Next line is a hack, itcompensates for
			 * unput's treatment of \n.
			 */
			lineno++;
			break;
		case ';':
			RET(';');
		case '\\':
			if (peek() == '\n') {
				input();
				lineno++;
			} else if (peek() == '\r') {
				input(); input();	/* \n */
				lineno++;
			} else {
				RET(c);
			}
			break;
		case '&':
			if (peek() == '&') {
				input(); RET(AND);
			} else
				RET('&');
		case '|':
			if (peek() == '|') {
				input(); RET(BOR);
			} else
				RET('|');
		case '!':
			if (peek() == '=') {
				input(); yylval.i = NE; RET(NE);
			} else if (peek() == '~') {
				input(); yylval.i = NOTMATCH; RET(MATCHOP);
			} else
				RET(NOT);
		case '~':
			yylval.i = MATCH;
			RET(MATCHOP);
		case '<':
			if (peek() == '=') {
				input(); yylval.i = LE; RET(LE);
			} else {
				yylval.i = LT; RET(LT);
			}
		case '=':
			if (peek() == '=') {
				input(); yylval.i = EQ; RET(EQ);
			} else {
				yylval.i = ASSIGN; RET(ASGNOP);
			}
		case '>':
			if (peek() == '=') {
				input(); yylval.i = GE; RET(GE);
			} else if (peek() == '>') {
				input(); yylval.i = APPEND; RET(APPEND);
			} else {
				yylval.i = GT; RET(GT);
			}
		case '+':
			if (peek() == '+') {
				input(); yylval.i = INCR; RET(INCR);
			} else if (peek() == '=') {
				input(); yylval.i = ADDEQ; RET(ASGNOP);
			} else
				RET('+');
		case '-':
			if (peek() == '-') {
				input(); yylval.i = DECR; RET(DECR);
			} else if (peek() == '=') {
				input(); yylval.i = SUBEQ; RET(ASGNOP);
			} else
				RET('-');
		case '*':
			if (peek() == '=') {	/* *= */
				input(); yylval.i = MULTEQ; RET(ASGNOP);
			} else if (peek() == '*') {	/* ** or **= */
				input();	/* eat 2nd * */
				if (peek() == '=') {
					input(); yylval.i = POWEQ; RET(ASGNOP);
				} else {
					RET(POWER);
				}
			} else
				RET('*');
		case '/':
			RET('/');
		case '%':
			if (peek() == '=') {
				input(); yylval.i = MODEQ; RET(ASGNOP);
			} else
				RET('%');
		case '^':
			if (peek() == '=') {
				input(); yylval.i = POWEQ; RET(ASGNOP);
			} else
				RET(POWER);

		case '$':
			/* BUG: awkward, if not wrong */
			c = gettok(&buf, &bufsize);
			if (isalpha(c)) {
				if (strcmp(buf, "NF") == 0) {	/* very special */
					unputstr("(NF)");
					RET(INDIRECT);
				}
				c = peek();
				if (c == '(' || c == '[' || (infunc && isarg(buf) >= 0)) {
					unputstr(buf);
					RET(INDIRECT);
				}
				yylval.cp = setsymtab(buf, "", 0.0, STR|NUM, symtab);
				RET(IVAR);
			} else if (c == 0) {	/*  */
				SYNTAX( "unexpected end of input after $" );
				RET(';');
			} else {
				unputstr(buf);
				RET(INDIRECT);
			}

		case '}':
			if (--bracecnt < 0)
				SYNTAX( "extra }" );
			sc = true;
			RET(';');
		case ']':
			if (--brackcnt < 0)
				SYNTAX( "extra ]" );
			RET(']');
		case ')':
			if (--parencnt < 0)
				SYNTAX( "extra )" );
			RET(')');
		case '{':
			bracecnt++;
			RET('{');
		case '[':
			brackcnt++;
			RET('[');
		case '(':
			parencnt++;
			RET('(');

		case '"':
			return string();	/* BUG: should be like tran.c ? */

		default:
			RET(c);
		}
	}
}

int string(void)
{
	int c, n;
	char *s, *bp;
	static char *buf = NULL;
	static int bufsz = 500;

	if (buf == NULL && (buf = (char *) malloc(bufsz)) == NULL)
		FATAL("out of space for strings");
	for (bp = buf; (c = input()) != '"'; ) {
		if (!adjbuf(&buf, &bufsz, bp-buf+2, 500, &bp, "string"))
			FATAL("out of space for string %.10s...", buf);
		switch (c) {
		case '\n':
		case '\r':
		case 0:
			*bp = '\0';
			SYNTAX( "non-terminated string %.10s...", buf );
			if (c == 0)	/* hopeless */
				FATAL( "giving up" );
			lineno++;
			break;
		case '\\':
			c = input();
			switch (c) {
			case '\n': break;
			case '"': *bp++ = '"'; break;
			case 'n': *bp++ = '\n'; break;
			case 't': *bp++ = '\t'; break;
			case 'f': *bp++ = '\f'; break;
			case 'r': *bp++ = '\r'; break;
			case 'b': *bp++ = '\b'; break;
			case 'v': *bp++ = '\v'; break;
			case 'a': *bp++ = '\a'; break;
			case '\\': *bp++ = '\\'; break;

			case '0': case '1': case '2': /* octal: \d \dd \ddd */
			case '3': case '4': case '5': case '6': case '7':
				n = c - '0';
				if ((c = peek()) >= '0' && c < '8') {
					n = 8 * n + input() - '0';
					if ((c = peek()) >= '0' && c < '8')
						n = 8 * n + input() - '0';
				}
				*bp++ = n;
				break;

			case 'x':	/* hex  \x0-9a-fA-F + */
			    {	char xbuf[100], *px;
				for (px = xbuf; (c = input()) != 0 && px-xbuf < 100-2; ) {
					if (isdigit(c)
					 || (c >= 'a' && c <= 'f')
					 || (c >= 'A' && c <= 'F'))
						*px++ = c;
					else
						break;
				}
				*px = 0;
				unput(c);
	  			sscanf(xbuf, "%x", (unsigned int *) &n);
				*bp++ = n;
				break;
			    }

			default:
				*bp++ = c;
				break;
			}
			break;
		default:
			*bp++ = c;
			break;
		}
	}
	*bp = 0;
	s = tostring(buf);
	*bp++ = ' '; *bp++ = '\0';
	yylval.cp = setsymtab(buf, s, 0.0, CON|STR|DONTFREE, symtab);
	free(s);
	RET(STRING);
}


static int binsearch(char *w, const Keyword *kp, int n)
{
	int cond, low, mid, high;

	low = 0;
	high = n - 1;
	while (low <= high) {
		mid = (low + high) / 2;
		if ((cond = strcmp(w, kp[mid].word)) < 0)
			high = mid - 1;
		else if (cond > 0)
			low = mid + 1;
		else
			return mid;
	}
	return -1;
}

int word(char *w)
{
	const Keyword *kp;
	int c, n;

	n = binsearch(w, keywords, sizeof(keywords)/sizeof(keywords[0]));
	if (n != -1) {	/* found in table */
		kp = keywords + n;
		yylval.i = kp->sub;
		switch (kp->type) {	/* special handling */
		case BLTIN:
			if (kp->sub == FSYSTEM && safe)
				SYNTAX( "system is unsafe" );
			RET(kp->type);
		case FUNC:
			if (infunc)
				SYNTAX( "illegal nested function" );
			RET(kp->type);
		case RETURN:
			if (!infunc)
				SYNTAX( "return not in function" );
			RET(kp->type);
		case VARNF:
			yylval.cp = setsymtab("NF", "", 0.0, NUM, symtab);
			RET(VARNF);
		default:
			RET(kp->type);
		}
	}
	c = peek();	/* look for '(' */
	if (c != '(' && infunc && (n=isarg(w)) >= 0) {
		yylval.i = n;
		RET(ARG);
	} else {
		yylval.cp = setsymtab(w, "", 0.0, STR|NUM|DONTFREE, symtab);
		if (c == '(') {
			RET(CALL);
		} else {
			RET(VAR);
		}
	}
}

void startreg(void)	/* next call to yylex will return a regular expression */
{
	reg = true;
}

int regexpr(void)
{
	int c;
	static char *buf = NULL;
	static int bufsz = 500;
	char *bp;

	if (buf == NULL && (buf = (char *) malloc(bufsz)) == NULL)
		FATAL("out of space for rex expr");
	bp = buf;
	for ( ; (c = input()) != '/' && c != 0; ) {
		if (!adjbuf(&buf, &bufsz, bp-buf+3, 500, &bp, "regexpr"))
			FATAL("out of space for reg expr %.10s...", buf);
		if (c == '\n') {
			*bp = '\0';
			SYNTAX( "newline in regular expression %.10s...", buf );
			unput('\n');
			break;
		} else if (c == '\\') {
			*bp++ = '\\';
			*bp++ = input();
		} else {
			*bp++ = c;
		}
	}
	*bp = 0;
	if (c == 0)
		SYNTAX("non-terminated regular expression %.10s...", buf);
	yylval.s = tostring(buf);
	unput('/');
	RET(REGEXPR);
}

/* low-level lexical stuff, sort of inherited from lex */

char	ebuf[300];
char	*ep = ebuf;
char	yysbuf[100];	/* pushback buffer */
char	*yysptr = yysbuf;
FILE	*yyin = NULL;

int input(void)	/* get next lexical input character */
{
	int c;
	extern char *lexprog;

	if (yysptr > yysbuf)
		c = (uschar)*--yysptr;
	else if (lexprog != NULL) {	/* awk '...' */
		if ((c = (uschar)*lexprog) != 0)
			lexprog++;
	} else				/* awk -f ... */
		c = pgetc();
	if (c == EOF)
		c = 0;
	if (ep >= ebuf + sizeof ebuf)
		ep = ebuf;
	*ep = c;
	if (c != 0) {
		ep++;
	}
	return (c);
}

void unput(int c)	/* put lexical character back on input */
{
	if (c == '\n')  
		lineno--;
	if (yysptr >= yysbuf + sizeof(yysbuf))
		FATAL("pushed back too much: %.20s...", yysbuf);
	*yysptr++ = c;
	if (--ep < ebuf)
		ep = ebuf + sizeof(ebuf) - 1;
}

void unputstr(const char *s)	/* put a string back on input */
{
	int i;

	for (i = strlen(s)-1; i >= 0; i--)
		unput(s[i]);
}