/*
** $Id: lua.c,v 1.206 2012/09/29 20:07:06 roberto Exp $
** Lua stand-alone interpreter
** See Copyright Notice in lua.h
*/


#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define lua_c

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


#if !defined(LUA_PROMPT)
#define LUA_PROMPT  "> "
#define LUA_PROMPT2 ">> "
#endif

#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME "lua"
#endif

#if !defined(LUA_MAXINPUT)
#define LUA_MAXINPUT 512
#endif

#if !defined(LUA_INIT)
#define LUA_INIT "LUA_INIT"
#endif

#define LUA_INITVERSION  \
    LUA_INIT "_" LUA_VERSION_MAJOR "_" LUA_VERSION_MINOR


/*
** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
** is, whether we're running lua interactively).
*/
#if defined(LUA_USE_ISATTY)
#include <unistd.h>
#define lua_stdin_is_tty() isatty(0)
#elif defined(LUA_WIN)
#include <io.h>
#include <stdio.h>
#define lua_stdin_is_tty() _isatty(_fileno(stdin))
#else
#define lua_stdin_is_tty() 1  /* assume stdin is a tty */
#endif


/*
** lua_readline defines how to show a prompt and then read a line from
** the standard input.
** lua_saveline defines how to "save" a read line in a "history".
** lua_freeline defines how to free a line read by lua_readline.
*/
#if defined(LUA_USE_READLINE)

#include <stdio.h>
#include <readline/readline.h>
#include <readline/history.h>
#define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
#define lua_saveline(L,idx) \
    if (lua_rawlen(L,idx) > 0)  /* non-empty line? */ \
        add_history(lua_tostring(L, idx));  /* add it to history */
#define lua_freeline(L,b) ((void)L, free(b))

#elif !defined(lua_readline)

#define lua_readline(L,b,p) \
    ((void)L, fputs(p, stdout), fflush(stdout),  /* show prompt */ \
     fgets(b, LUA_MAXINPUT, stdin) != NULL)  /* get line */
#define lua_saveline(L,idx) { (void)L; (void)idx; }
#define lua_freeline(L,b) { (void)L; (void)b; }

#endif




static lua_State *globalL = NULL;

static const char *progname = LUA_PROGNAME;



static void lstop(lua_State *L, lua_Debug *ar) {
    (void)ar;  /* unused arg. */
    lua_sethook(L, NULL, 0, 0);
    luaL_error(L, "interrupted!");
}


static void laction(int i) {
    signal(i, SIG_DFL); /* if another SIGINT happens before lstop,
                              terminate process (default action) */
    lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
}


static void print_usage(const char *badoption) {
    luai_writestringerror("%s: ", progname);
    if (badoption[1] == 'e' || badoption[1] == 'l')
        luai_writestringerror("'%s' needs argument\n", badoption);
    else
        luai_writestringerror("unrecognized option '%s'\n", badoption);
    luai_writestringerror(
        "usage: %s [options] [script [args]]\n"
        "Available options are:\n"
        "  -e stat  execute string " LUA_QL("stat") "\n"
        "  -i       enter interactive mode after executing " LUA_QL("script") "\n"
        "  -l name  require library " LUA_QL("name") "\n"
        "  -v       show version information\n"
        "  -E       ignore environment variables\n"
        "  --       stop handling options\n"
        "  -        stop handling options and execute stdin\n"
        ,
        progname);
}


static void l_message(const char *pname, const char *msg) {
    if (pname) luai_writestringerror("%s: ", pname);
    luai_writestringerror("%s\n", msg);
}


static int report(lua_State *L, int status) {
    if (status != LUA_OK && !lua_isnil(L, -1)) {
        const char *msg = lua_tostring(L, -1);
        if (msg == NULL) msg = "(error object is not a string)";
        l_message(progname, msg);
        lua_pop(L, 1);
        /* force a complete garbage collection in case of errors */
        lua_gc(L, LUA_GCCOLLECT, 0);
    }
    return status;
}


/* the next function is called unprotected, so it must avoid errors */
static void finalreport(lua_State *L, int status) {
    if (status != LUA_OK) {
        const char *msg = (lua_type(L, -1) == LUA_TSTRING) ? lua_tostring(L, -1)
                          : NULL;
        if (msg == NULL) msg = "(error object is not a string)";
        l_message(progname, msg);
        lua_pop(L, 1);
    }
}


static int traceback(lua_State *L) {
    const char *msg = lua_tostring(L, 1);
    if (msg)
        luaL_traceback(L, L, msg, 1);
    else if (!lua_isnoneornil(L, 1)) {  /* is there an error object? */
        if (!luaL_callmeta(L, 1, "__tostring"))  /* try its 'tostring' metamethod */
            lua_pushliteral(L, "(no error message)");
    }
    return 1;
}


static int docall(lua_State *L, int narg, int nres) {
    int status;
    int base = lua_gettop(L) - narg;  /* function index */
    lua_pushcfunction(L, traceback);  /* push traceback function */
    lua_insert(L, base);  /* put it under chunk and args */
    globalL = L;  /* to be available to 'laction' */
    signal(SIGINT, laction);
    status = lua_pcall(L, narg, nres, base);
    signal(SIGINT, SIG_DFL);
    lua_remove(L, base);  /* remove traceback function */
    return status;
}


static void print_version(void) {
    luai_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));
    luai_writeline();
}


static int getargs(lua_State *L, char **argv, int n) {
    int narg;
    int i;
    int argc = 0;
    while (argv[argc]) argc++;  /* count total number of arguments */
    narg = argc - (n + 1);  /* number of arguments to the script */
    luaL_checkstack(L, narg + 3, "too many arguments to script");
    for (i = n + 1; i < argc; i++)
        lua_pushstring(L, argv[i]);
    lua_createtable(L, narg, n + 1);
    for (i = 0; i < argc; i++) {
        lua_pushstring(L, argv[i]);
        lua_rawseti(L, -2, i - n);
    }
    return narg;
}


static int dofile(lua_State *L, const char *name) {
    int status = luaL_loadfile(L, name);
    if (status == LUA_OK) status = docall(L, 0, 0);
    return report(L, status);
}


static int dostring(lua_State *L, const char *s, const char *name) {
    int status = luaL_loadbuffer(L, s, strlen(s), name);
    if (status == LUA_OK) status = docall(L, 0, 0);
    return report(L, status);
}


static int dolibrary(lua_State *L, const char *name) {
    int status;
    lua_getglobal(L, "require");
    lua_pushstring(L, name);
    status = docall(L, 1, 1);  /* call 'require(name)' */
    if (status == LUA_OK)
        lua_setglobal(L, name);  /* global[name] = require return */
    return report(L, status);
}


static const char *get_prompt(lua_State *L, int firstline) {
    const char *p;
    lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
    p = lua_tostring(L, -1);
    if (p == NULL) p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
    return p;
}

/* mark in error messages for incomplete statements */
#define EOFMARK "<eof>"
#define marklen (sizeof(EOFMARK)/sizeof(char) - 1)

static int incomplete(lua_State *L, int status) {
    if (status == LUA_ERRSYNTAX) {
        size_t lmsg;
        const char *msg = lua_tolstring(L, -1, &lmsg);
        if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0) {
            lua_pop(L, 1);
            return 1;
        }
    }
    return 0;  /* else... */
}


static int pushline(lua_State *L, int firstline) {
    char buffer[LUA_MAXINPUT];
    char *b = buffer;
    size_t l;
    const char *prmt = get_prompt(L, firstline);
    int readstatus = lua_readline(L, b, prmt);
    lua_pop(L, 1);  /* remove result from 'get_prompt' */
    if (readstatus == 0)
        return 0;  /* no input */
    l = strlen(b);
    if (l > 0 && b[l - 1] == '\n') /* line ends with newline? */
        b[l - 1] = '\0'; /* remove it */
    if (firstline && b[0] == '=')  /* first line starts with `=' ? */
        lua_pushfstring(L, "return %s", b + 1); /* change it to `return' */
    else
        lua_pushstring(L, b);
    lua_freeline(L, b);
    return 1;
}


static int loadline(lua_State *L) {
    int status;
    lua_settop(L, 0);
    if (!pushline(L, 1))
        return -1;  /* no input */
    for (;;) {  /* repeat until gets a complete line */
        size_t l;
        const char *line = lua_tolstring(L, 1, &l);
        status = luaL_loadbuffer(L, line, l, "=stdin");
        if (!incomplete(L, status)) break;  /* cannot try to add lines? */
        if (!pushline(L, 0))  /* no more input? */
            return -1;
        lua_pushliteral(L, "\n");  /* add a new line... */
        lua_insert(L, -2);  /* ...between the two lines */
        lua_concat(L, 3);  /* join them */
    }
    lua_saveline(L, 1);
    lua_remove(L, 1);  /* remove line */
    return status;
}


static void dotty(lua_State *L) {
    int status;
    const char *oldprogname = progname;
    progname = NULL;
    while ((status = loadline(L)) != -1) {
        if (status == LUA_OK) status = docall(L, 0, LUA_MULTRET);
        report(L, status);
        if (status == LUA_OK && lua_gettop(L) > 0) {  /* any result to print? */
            luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
            lua_getglobal(L, "print");
            lua_insert(L, 1);
            if (lua_pcall(L, lua_gettop(L) - 1, 0, 0) != LUA_OK)
                l_message(progname, lua_pushfstring(L,
                                                    "error calling " LUA_QL("print") " (%s)",
                                                    lua_tostring(L, -1)));
        }
    }
    lua_settop(L, 0);  /* clear stack */
    luai_writeline();
    progname = oldprogname;
}


static int handle_script(lua_State *L, char **argv, int n) {
    int status;
    const char *fname;
    int narg = getargs(L, argv, n);  /* collect arguments */
    lua_setglobal(L, "arg");
    fname = argv[n];
    if (strcmp(fname, "-") == 0 && strcmp(argv[n - 1], "--") != 0)
        fname = NULL;  /* stdin */
    status = luaL_loadfile(L, fname);
    lua_insert(L, -(narg + 1));
    if (status == LUA_OK)
        status = docall(L, narg, LUA_MULTRET);
    else
        lua_pop(L, narg);
    return report(L, status);
}


/* check that argument has no extra characters at the end */
#define noextrachars(x) {if ((x)[2] != '\0') return -1;}


/* indices of various argument indicators in array args */
#define has_i 0 /* -i */
#define has_v 1 /* -v */
#define has_e 2 /* -e */
#define has_E 3 /* -E */

#define num_has 4 /* number of 'has_*' */


static int collectargs(char **argv, int *args) {
    int i;
    for (i = 1; argv[i] != NULL; i++) {
        if (argv[i][0] != '-')  /* not an option? */
            return i;
        switch (argv[i][1]) {  /* option */
            case '-':
                noextrachars(argv[i]);
                return (argv[i + 1] != NULL ? i + 1 : 0);
            case '\0':
                return i;
            case 'E':
                args[has_E] = 1;
                break;
            case 'i':
                noextrachars(argv[i]);
                args[has_i] = 1;  /* go through */
            case 'v':
                noextrachars(argv[i]);
                args[has_v] = 1;
                break;
            case 'e':
                args[has_e] = 1;  /* go through */
            case 'l':  /* both options need an argument */
                if (argv[i][2] == '\0') {  /* no concatenated argument? */
                    i++;  /* try next 'argv' */
                    if (argv[i] == NULL || argv[i][0] == '-')
                        return -(i - 1);  /* no next argument or it is another option */
                }
                break;
            default:  /* invalid option; return its index... */
                return -i;  /* ...as a negative value */
        }
    }
    return 0;
}


static int runargs(lua_State *L, char **argv, int n) {
    int i;
    for (i = 1; i < n; i++) {
        lua_assert(argv[i][0] == '-');
        switch (argv[i][1]) {  /* option */
            case 'e': {
                const char *chunk = argv[i] + 2;
                if (*chunk == '\0') chunk = argv[++i];
                lua_assert(chunk != NULL);
                if (dostring(L, chunk, "=(command line)") != LUA_OK)
                    return 0;
                break;
            }
            case 'l': {
                const char *filename = argv[i] + 2;
                if (*filename == '\0') filename = argv[++i];
                lua_assert(filename != NULL);
                if (dolibrary(L, filename) != LUA_OK)
                    return 0;  /* stop if file fails */
                break;
            }
            default:
                break;
        }
    }
    return 1;
}


static int handle_luainit(lua_State *L) {
    const char *name = "=" LUA_INITVERSION;
    const char *init = getenv(name + 1);
    if (init == NULL) {
        name = "=" LUA_INIT;
        init = getenv(name + 1);  /* try alternative name */
    }
    if (init == NULL) return LUA_OK;
    else if (init[0] == '@')
        return dofile(L, init + 1);
    else
        return dostring(L, init, name);
}


static int pmain(lua_State *L) {
    int argc = (int)lua_tointeger(L, 1);
    char **argv = (char **)lua_touserdata(L, 2);
    int script;
    int args[num_has];
    args[has_i] = args[has_v] = args[has_e] = args[has_E] = 0;
    if (argv[0] && argv[0][0]) progname = argv[0];
    script = collectargs(argv, args);
    if (script < 0) {  /* invalid arg? */
        print_usage(argv[-script]);
        return 0;
    }
    if (args[has_v]) print_version();
    if (args[has_E]) {  /* option '-E'? */
        lua_pushboolean(L, 1);  /* signal for libraries to ignore env. vars. */
        lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
    }
    /* open standard libraries */
    luaL_checkversion(L);
    lua_gc(L, LUA_GCSTOP, 0);  /* stop collector during initialization */
    luaL_openlibs(L);  /* open libraries */
    lua_gc(L, LUA_GCRESTART, 0);
    if (!args[has_E] && handle_luainit(L) != LUA_OK)
        return 0;  /* error running LUA_INIT */
    /* execute arguments -e and -l */
    if (!runargs(L, argv, (script > 0) ? script : argc)) return 0;
    /* execute main script (if there is one) */
    if (script && handle_script(L, argv, script) != LUA_OK) return 0;
    if (args[has_i])  /* -i option? */
        dotty(L);
    else if (script == 0 && !args[has_e] && !args[has_v]) {  /* no arguments? */
        if (lua_stdin_is_tty()) {
            print_version();
            dotty(L);
        } else dofile(L, NULL); /* executes stdin as a file */
    }
    lua_pushboolean(L, 1);  /* signal no errors */
    return 1;
}


int main(int argc, char **argv) {
    int status, result;
    lua_State *L = luaL_newstate();  /* create state */
    if (L == NULL) {
        l_message(argv[0], "cannot create state: not enough memory");
        return EXIT_FAILURE;
    }
    /* call 'pmain' in protected mode */
    lua_pushcfunction(L, &pmain);
    lua_pushinteger(L, argc);  /* 1st argument */
    lua_pushlightuserdata(L, argv); /* 2nd argument */
    status = lua_pcall(L, 2, 1, 0);
    result = lua_toboolean(L, -1);  /* get result */
    finalreport(L, status);
    lua_close(L);
    return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
}

