/*
** $Id: lstrlib.c,v 1.56 2000/10/27 16:15:53 roberto Exp $
** Standard library for string operations and pattern-matching
** See Copyright Notice in lua.h
*/


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

#include "lua.h"

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



static int str_len (lua_State *L)
{
    size_t l;
    luaL_check_lstr(L, 1, &l);
    lua_pushnumber(L, CComplex(l,0));
    return 1;
}


static long posrelat (long pos, size_t len)
{
    /* relative string position: negative means back from end */
    return (pos>=0) ? pos : (long)len+pos+1;
}


static int str_sub (lua_State *L)
{
    size_t l;
    const char *s = luaL_check_lstr(L, 1, &l);
    long start = posrelat(luaL_check_long(L, 2), l);
    long end = posrelat(luaL_opt_long(L, 3, -1), l);
    if (start < 1) start = 1;
    if (end > (long)l) end = l;
    if (start <= end)
        lua_pushlstring(L, s+start-1, end-start+1);
    else lua_pushstring(L, "");
    return 1;
}


static int str_lower (lua_State *L)
{
    size_t l;
    size_t i;
    luaL_Buffer b;
    const char *s = luaL_check_lstr(L, 1, &l);
    luaL_buffinit(L, &b);
    for (i=0; i<l; i++)
        luaL_putchar(&b, tolower((unsigned char)(s[i])));
    luaL_pushresult(&b);
    return 1;
}


static int str_upper (lua_State *L)
{
    size_t l;
    size_t i;
    luaL_Buffer b;
    const char *s = luaL_check_lstr(L, 1, &l);
    luaL_buffinit(L, &b);
    for (i=0; i<l; i++)
        luaL_putchar(&b, toupper((unsigned char)(s[i])));
    luaL_pushresult(&b);
    return 1;
}

static int str_rep (lua_State *L)
{
    size_t l;
    luaL_Buffer b;
    const char *s = luaL_check_lstr(L, 1, &l);
    int n = luaL_check_int(L, 2);
    luaL_buffinit(L, &b);
    while (n-- > 0)
        luaL_addlstring(&b, s, l);
    luaL_pushresult(&b);
    return 1;
}


static int str_byte (lua_State *L)
{
    size_t l;
    const char *s = luaL_check_lstr(L, 1, &l);
    long pos = posrelat(luaL_opt_long(L, 2, 1), l);
    luaL_arg_check(L, 0<pos && (size_t)pos<=l, 2,  "out of range");
    lua_pushnumber(L, (unsigned char)s[pos-1]);
    return 1;
}


static int str_char (lua_State *L)
{
    int n = lua_gettop(L);  /* number of arguments */
    int i;
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    for (i=1; i<=n; i++)
    {
        int c = luaL_check_int(L, i);
        luaL_arg_check(L, (unsigned char)c == c, i, "invalid value");
        luaL_putchar(&b, (unsigned char)c);
    }
    luaL_pushresult(&b);
    return 1;
}



/*
** {======================================================
** PATTERN MATCHING
** =======================================================
*/

#ifndef MAX_CAPTURES
#define MAX_CAPTURES 32  /* arbitrary limit */
#endif


struct Capture
{
    const char *src_end;  /* end ('\0') of source string */
    int level;  /* total number of captures (finished or unfinished) */
    struct
    {
        const char *init;
        long len;  /* -1 signals unfinished capture */
    } capture[MAX_CAPTURES];
};


#define ESC		'%'
#define SPECIALS	"^$*+?.([%-"


static int check_capture (lua_State *L, int l, struct Capture *cap)
{
    l -= '1';
    if (!(0 <= l && l < cap->level && cap->capture[l].len != -1))
        lua_error(L, "invalid capture index");
    return l;
}


static int capture_to_close (lua_State *L, struct Capture *cap)
{
    int level = cap->level;
    for (level--; level>=0; level--)
        if (cap->capture[level].len == -1) return level;
    lua_error(L, "invalid pattern capture");
    return 0;  /* to avoid warnings */
}


const char *luaI_classend (lua_State *L, const char *p)
{
    switch (*p++)
    {
    case ESC:
        if (*p == '\0') lua_error(L, "malformed pattern (ends with `%')");
        return p+1;
    case '[':
        if (*p == '^') p++;
        do    /* look for a ']' */
        {
            if (*p == '\0') lua_error(L, "malformed pattern (missing `]')");
            if (*(p++) == ESC && *p != '\0') p++;  /* skip escapes (e.g. '%]') */
        }
        while (*p != ']');
        return p+1;
    default:
        return p;
    }
}


static int match_class (int c, int cl)
{
    int res;
    switch (tolower(cl))
    {
    case 'a' :
        res = isalpha(c);
        break;
    case 'c' :
        res = iscntrl(c);
        break;
    case 'd' :
        res = isdigit(c);
        break;
    case 'l' :
        res = islower(c);
        break;
    case 'p' :
        res = ispunct(c);
        break;
    case 's' :
        res = isspace(c);
        break;
    case 'u' :
        res = isupper(c);
        break;
    case 'w' :
        res = isalnum(c);
        break;
    case 'x' :
        res = isxdigit(c);
        break;
    case 'z' :
        res = (c == '\0');
        break;
    default:
        return (cl == c);
    }
    return (islower(cl) ? res : !res);
}



static int matchbracketclass (int c, const char *p, const char *endclass)
{
    int sig = 1;
    if (*(p+1) == '^')
    {
        sig = 0;
        p++;  /* skip the '^' */
    }
    while (++p < endclass)
    {
        if (*p == ESC)
        {
            p++;
            if (match_class(c, (unsigned char)*p))
                return sig;
        }
        else if ((*(p+1) == '-') && (p+2 < endclass))
        {
            p+=2;
            if ((int)(unsigned char)*(p-2) <= c && c <= (int)(unsigned char)*p)
                return sig;
        }
        else if ((int)(unsigned char)*p == c) return sig;
    }
    return !sig;
}



int luaI_singlematch (int c, const char *p, const char *ep)
{
    switch (*p)
    {
    case '.':  /* matches any char */
        return 1;
    case ESC:
        return match_class(c, (unsigned char)*(p+1));
    case '[':
        return matchbracketclass(c, p, ep-1);
    default:
        return ((unsigned char)*p == c);
    }
}


static const char *match (lua_State *L, const char *s, const char *p,
                          struct Capture *cap);


static const char *matchbalance (lua_State *L, const char *s, const char *p,
                                 struct Capture *cap)
{
    if (*p == 0 || *(p+1) == 0)
        lua_error(L, "unbalanced pattern");
    if (*s != *p) return NULL;
    else
    {
        int b = *p;
        int e = *(p+1);
        int cont = 1;
        while (++s < cap->src_end)
        {
            if (*s == e)
            {
                if (--cont == 0) return s+1;
            }
            else if (*s == b) cont++;
        }
    }
    return NULL;  /* string ends out of balance */
}


static const char *max_expand (lua_State *L, const char *s, const char *p,
                               const char *ep, struct Capture *cap)
{
    long i = 0;  /* counts maximum expand for item */
    while ((s+i)<cap->src_end && luaI_singlematch((unsigned char)*(s+i), p, ep))
        i++;
    /* keeps trying to match with the maximum repetitions */
    while (i>=0)
    {
        const char *res = match(L, (s+i), ep+1, cap);
        if (res) return res;
        i--;  /* else didn't match; reduce 1 repetition to try again */
    }
    return NULL;
}


static const char *min_expand (lua_State *L, const char *s, const char *p,
                               const char *ep, struct Capture *cap)
{
    for (;;)
    {
        const char *res = match(L, s, ep+1, cap);
        if (res != NULL)
            return res;
        else if (s<cap->src_end && luaI_singlematch((unsigned char)*s, p, ep))
            s++;  /* try with one more repetition */
        else return NULL;
    }
}


static const char *start_capture (lua_State *L, const char *s, const char *p,
                                  struct Capture *cap)
{
    const char *res;
    int level = cap->level;
    if (level >= MAX_CAPTURES) lua_error(L, "too many captures");
    cap->capture[level].init = s;
    cap->capture[level].len = -1;
    cap->level = level+1;
    if ((res=match(L, s, p+1, cap)) == NULL)  /* match failed? */
        cap->level--;  /* undo capture */
    return res;
}


static const char *end_capture (lua_State *L, const char *s, const char *p,
                                struct Capture *cap)
{
    int l = capture_to_close(L, cap);
    const char *res;
    cap->capture[l].len = s - cap->capture[l].init;  /* close capture */
    if ((res = match(L, s, p+1, cap)) == NULL)  /* match failed? */
        cap->capture[l].len = -1;  /* undo capture */
    return res;
}


static const char *match_capture (lua_State *L, const char *s, int level,
                                  struct Capture *cap)
{
    int l = check_capture(L, level, cap);
    size_t len = cap->capture[l].len;
    if ((size_t)(cap->src_end-s) >= len &&
            memcmp(cap->capture[l].init, s, len) == 0)
        return s+len;
    else return NULL;
}


static const char *match (lua_State *L, const char *s, const char *p,
                          struct Capture *cap)
{
init: /* using goto's to optimize tail recursion */
    switch (*p)
    {
    case '(':  /* start capture */
        return start_capture(L, s, p, cap);
    case ')':  /* end capture */
        return end_capture(L, s, p, cap);
    case ESC:  /* may be %[0-9] or %b */
        if (isdigit((unsigned char)(*(p+1))))    /* capture? */
        {
            s = match_capture(L, s, *(p+1), cap);
            if (s == NULL) return NULL;
            p+=2;
            goto init;  /* else return match(L, s, p+2, cap) */
        }
        else if (*(p+1) == 'b')    /* balanced string? */
        {
            s = matchbalance(L, s, p+2, cap);
            if (s == NULL) return NULL;
            p+=4;
            goto init;  /* else return match(L, s, p+4, cap); */
        }
        else goto dflt;  /* case default */
    case '\0':  /* end of pattern */
        return s;  /* match succeeded */
    case '$':
        if (*(p+1) == '\0')  /* is the '$' the last char in pattern? */
            return (s == cap->src_end) ? s : NULL;  /* check end of string */
        else goto dflt;
    default:
dflt:    /* it is a pattern item */
        {
            const char *ep = luaI_classend(L, p);  /* points to what is next */
            int m = s<cap->src_end && luaI_singlematch((unsigned char)*s, p, ep);
            switch (*ep)
            {
            case '?':    /* optional */
            {
                const char *res;
                if (m && ((res=match(L, s+1, ep+1, cap)) != NULL))
                    return res;
                p=ep+1;
                goto init;  /* else return match(L, s, ep+1, cap); */
            }
            case '*':  /* 0 or more repetitions */
                return max_expand(L, s, p, ep, cap);
            case '+':  /* 1 or more repetitions */
                return (m ? max_expand(L, s+1, p, ep, cap) : NULL);
            case '-':  /* 0 or more repetitions (minimum) */
                return min_expand(L, s, p, ep, cap);
            default:
                if (!m) return NULL;
                s++;
                p=ep;
                goto init;  /* else return match(L, s+1, ep, cap); */
            }
        }
    }
}



static const char *lmemfind (const char *s1, size_t l1,
                             const char *s2, size_t l2)
{
    if (l2 == 0) return s1;  /* empty strings are everywhere */
    else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
    else
    {
        const char *init;  /* to search for a `*s2' inside `s1' */
        l2--;  /* 1st char will be checked by `memchr' */
        l1 = l1-l2;  /* `s2' cannot be found after that */
        while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL)
        {
            init++;   /* 1st char is already checked */
            if (memcmp(init, s2+1, l2) == 0)
                return init-1;
            else    /* correct `l1' and `s1' to try again */
            {
                l1 -= init-s1;
                s1 = init;
            }
        }
        return NULL;  /* not found */
    }
}


static int push_captures (lua_State *L, struct Capture *cap)
{
    int i;
    luaL_checkstack(L, cap->level, "too many captures");
    for (i=0; i<cap->level; i++)
    {
        int l = cap->capture[i].len;
        if (l == -1) lua_error(L, "unfinished capture");
        lua_pushlstring(L, cap->capture[i].init, l);
    }
    return cap->level;  /* number of strings pushed */
}


static int str_find (lua_State *L)
{
    size_t l1, l2;
    const char *s = luaL_check_lstr(L, 1, &l1);
    const char *p = luaL_check_lstr(L, 2, &l2);
    long init = posrelat(luaL_opt_long(L, 3, 1), l1) - 1;
    struct Capture cap;
    luaL_arg_check(L, 0 <= init && (size_t)init <= l1, 3, "out of range");
    if (lua_gettop(L) > 3 ||  /* extra argument? */
            strpbrk(p, SPECIALS) == NULL)    /* or no special characters? */
    {
        const char *s2 = lmemfind(s+init, l1-init, p, l2);
        if (s2)
        {
            lua_pushnumber(L, CComplex(s2-s+1,0));
            lua_pushnumber(L, CComplex(s2-s+l2,0));
            return 2;
        }
    }
    else
    {
        int anchor = (*p == '^') ? (p++, 1) : 0;
        const char *s1=s+init;
        cap.src_end = s+l1;
        do
        {
            const char *res;
            cap.level = 0;
            if ((res=match(L, s1, p, &cap)) != NULL)
            {
                lua_pushnumber(L, CComplex(int(s1-s+1)));  /* start */
                lua_pushnumber(L, CComplex(int(res-s)));   /* end */
                return push_captures(L, &cap) + 2;
            }
        }
        while (s1++<cap.src_end && !anchor);
    }
    lua_pushnil(L);  /* not found */
    return 1;
}


static void add_s (lua_State *L, luaL_Buffer *b, struct Capture *cap)
{
    if (lua_isstring(L, 3))
    {
        const char *news = lua_tostring(L, 3);
        size_t l = lua_strlen(L, 3);
        size_t i;
        for (i=0; i<l; i++)
        {
            if (news[i] != ESC)
                luaL_putchar(b, news[i]);
            else
            {
                i++;  /* skip ESC */
                if (!isdigit((unsigned char)news[i]))
                    luaL_putchar(b, news[i]);
                else
                {
                    int level = check_capture(L, news[i], cap);
                    luaL_addlstring(b, cap->capture[level].init, cap->capture[level].len);
                }
            }
        }
    }
    else    /* is a function */
    {
        int n;
        lua_pushvalue(L, 3);
        n = push_captures(L, cap);
        lua_rawcall(L, n, 1);
        if (lua_isstring(L, -1))
            luaL_addvalue(b);  /* add return to accumulated result */
        else
            lua_pop(L, 1);  /* function result is not a string: pop it */
    }
}


static int str_gsub (lua_State *L)
{
    size_t srcl;
    const char *src = luaL_check_lstr(L, 1, &srcl);
    const char *p = luaL_check_string(L, 2);
    int max_s = luaL_opt_int(L, 4, srcl+1);
    int anchor = (*p == '^') ? (p++, 1) : 0;
    int n = 0;
    struct Capture cap;
    luaL_Buffer b;
    luaL_arg_check(L,
                   lua_gettop(L) >= 3 && (lua_isstring(L, 3) || lua_isfunction(L, 3)),
                   3, "string or function expected");
    luaL_buffinit(L, &b);
    cap.src_end = src+srcl;
    while (n < max_s)
    {
        const char *e;
        cap.level = 0;
        e = match(L, src, p, &cap);
        if (e)
        {
            n++;
            add_s(L, &b, &cap);
        }
        if (e && e>src) /* non empty match? */
            src = e;  /* skip it */
        else if (src < cap.src_end)
            luaL_putchar(&b, *src++);
        else break;
        if (anchor) break;
    }
    luaL_addlstring(&b, src, cap.src_end-src);
    luaL_pushresult(&b);
    lua_pushnumber(L, n);  /* number of substitutions */
    return 2;
}

/* }====================================================== */


static void luaI_addquoted (lua_State *L, luaL_Buffer *b, int arg)
{
    size_t l;
    const char *s = luaL_check_lstr(L, arg, &l);
    luaL_putchar(b, '"');
    while (l--)
    {
        switch (*s)
        {
        case '"':
        case '\\':
        case '\n':
            luaL_putchar(b, '\\');
            luaL_putchar(b, *s);
            break;
        case '\0':
            luaL_addlstring(b, "\\000", 4);
            break;
        default:
            luaL_putchar(b, *s);
        }
        s++;
    }
    luaL_putchar(b, '"');
}

/* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
#define MAX_ITEM	512
/* maximum size of each format specification (such as '%-099.99d') */
#define MAX_FORMAT	20

static int str_format (lua_State *L)
{
    int arg = 1;
    const char *strfrmt = luaL_check_string(L, arg);
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    while (*strfrmt)
    {
        if (*strfrmt != '%')
            luaL_putchar(&b, *strfrmt++);
        else if (*++strfrmt == '%')
            luaL_putchar(&b, *strfrmt++);  /* %% */
        else   /* format item */
        {
            struct Capture cap;
            char form[MAX_FORMAT];  /* to store the format ('%...') */
            char buff[MAX_ITEM];  /* to store the formatted item */
            const char *initf = strfrmt;
            form[0] = '%';
            if (isdigit((unsigned char)*initf) && *(initf+1) == '$')
            {
                arg = *initf - '0';
                initf += 2;  /* skip the 'n$' */
            }
            arg++;
            cap.src_end = strfrmt+strlen(strfrmt)+1;
            cap.level = 0;
            strfrmt = match(L, initf, "[-+ #0]*(%d*)%.?(%d*)", &cap);
            if (cap.capture[0].len > 2 || cap.capture[1].len > 2 ||  /* < 100? */
                    strfrmt-initf > MAX_FORMAT-2)
                lua_error(L, "invalid format (width or precision too long)");
            strncpy(form+1, initf, strfrmt-initf+1); /* +1 to include conversion */
            form[strfrmt-initf+2] = 0;
            switch (*strfrmt++)
            {
            case 'c':
            case 'd':
            case 'i':
                sprintf(buff, form, luaL_check_int(L, arg));
                break;
            case 'o':
            case 'u':
            case 'x':
            case 'X':
                sprintf(buff, form, (unsigned int) Re(luaL_check_number(L, arg)));
                break;
            case 'e':
            case 'E':
            case 'f':
            case 'g':
            case 'G':
                sprintf(buff, form, luaL_check_number(L, arg));
                break;
            case 'q':
                luaI_addquoted(L, &b, arg);
                continue;  /* skip the "addsize" at the end */
            case 's':
            {
                size_t l;
                const char *s = luaL_check_lstr(L, arg, &l);
                if (cap.capture[1].len == 0 && l >= 100)
                {
                    /* no precision and string is too long to be formatted;
                       keep original string */
                    lua_pushvalue(L, arg);
                    luaL_addvalue(&b);
                    continue;  /* skip the "addsize" at the end */
                }
                else
                {
                    sprintf(buff, form, s);
                    break;
                }
            }
            default:  /* also treat cases 'pnLlh' */
                lua_error(L, "invalid option in `format'");
            }
            luaL_addlstring(&b, buff, strlen(buff));
        }
    }
    luaL_pushresult(&b);
    return 1;
}


static const struct luaL_reg strlib[] =
{
    {"strlen", str_len},
    {"strsub", str_sub},
    {"strlower", str_lower},
    {"strupper", str_upper},
    {"strchar", str_char},
    {"strrep", str_rep},
    {"ascii", str_byte},  /* for compatibility with 3.0 and earlier */
    {"strbyte", str_byte},
    {"format", str_format},
    {"strfind", str_find},
    {"gsub", str_gsub}
};


/*
** Open string library
*/
LUALIB_API void lua_strlibopen (lua_State *L)
{
    luaL_openl(L, strlib);
}
