/*
  string functions
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <setjmp.h>
#include <stdarg.h>
#include <assert.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/time.h>
#include <errno.h>
#include "llt.h"
#include "flisp.h"

value_t fl_stringp(value_t *args, u_int32_t nargs)
{
    argcount("string?", nargs, 1);
    return isstring(args[0]) ? FL_T : FL_F;
}

value_t fl_string_count(value_t *args, u_int32_t nargs)
{
    size_t start = 0;
    if (nargs < 1 || nargs > 3)
        argcount("string.count", nargs, 1);
    if (!isstring(args[0]))
        type_error("string.count", "string", args[0]);
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    size_t stop = len;
    if (nargs > 1) {
        start = toulong(args[1], "string.count");
        if (start > len)
            bounds_error("string.count", args[0], args[1]);
        if (nargs > 2) {
            stop = toulong(args[2], "string.count");
            if (stop > len)
                bounds_error("string.count", args[0], args[2]);
            if (stop <= start)
                return fixnum(0);
        }
    }
    char *str = cvalue_data(args[0]);
    return size_wrap(u8_charnum(str+start, stop-start));
}

value_t fl_string_reverse(value_t *args, u_int32_t nargs)
{
    argcount("string.reverse", nargs, 1);
    if (!isstring(args[0]))
        type_error("string.reverse", "string", args[0]);
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    value_t ns = cvalue_string(len);
    u8_reverse(cvalue_data(ns), cvalue_data(args[0]), len);
    return ns;
}

value_t fl_string_encode(value_t *args, u_int32_t nargs)
{
    argcount("string.encode", nargs, 1);
    if (iscvalue(args[0])) {
        cvalue_t *cv = (cvalue_t*)ptr(args[0]);
        fltype_t *t = cv_class(cv);
        if (t->eltype == wchartype) {
            size_t nc = cv_len(cv) / sizeof(uint32_t);
            uint32_t *ptr = (uint32_t*)cv_data(cv);
            size_t nbytes = u8_codingsize(ptr, nc);
            value_t str = cvalue_string(nbytes);
            ptr = cv_data((cvalue_t*)ptr(args[0]));  // relocatable pointer
            u8_toutf8(cvalue_data(str), nbytes, ptr, nc);
            return str;
        }
    }
    type_error("string.encode", "wchar array", args[0]);
}

value_t fl_string_decode(value_t *args, u_int32_t nargs)
{
    int term=0;
    if (nargs == 2) {
        term = (POP() != FL_F);
        nargs--;
    }
    argcount("string.decode", nargs, 1);
    if (!isstring(args[0]))
        type_error("string.decode", "string", args[0]);
    cvalue_t *cv = (cvalue_t*)ptr(args[0]);
    char *ptr = (char*)cv_data(cv);
    size_t nb = cv_len(cv);
    size_t nc = u8_charnum(ptr, nb);
    size_t newsz = nc*sizeof(uint32_t);
    if (term) newsz += sizeof(uint32_t);
    value_t wcstr = cvalue(wcstringtype, newsz);
    ptr = cv_data((cvalue_t*)ptr(args[0]));  // relocatable pointer
    uint32_t *pwc = cvalue_data(wcstr);
    u8_toucs(pwc, nc, ptr, nb);
    if (term) pwc[nc] = 0;
    return wcstr;
}

extern value_t fl_buffer(value_t *args, u_int32_t nargs);
extern value_t stream_to_string(value_t *ps);

value_t fl_string(value_t *args, u_int32_t nargs)
{
    if (nargs == 1 && isstring(args[0]))
        return args[0];
    value_t buf = fl_buffer(NULL, 0);
    ios_t *s = value2c(ios_t*,buf);
    uint32_t i;
    for (i=0; i < nargs; i++)
        print(s, args[i], 1);
    PUSH(buf);
    value_t outp = stream_to_string(&Stack[SP-1]);
    (void)POP();
    return outp;
}

value_t fl_string_split(value_t *args, u_int32_t nargs)
{
    argcount("string.split", nargs, 2);
    char *s = tostring(args[0], "string.split");
    char *delim = tostring(args[1], "string.split");
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    size_t dlen = cv_len((cvalue_t*)ptr(args[1]));
    PUSH(NIL);
    size_t ssz, tokend=0, tokstart=0, i=0;
    value_t c=NIL;
    size_t junk;
    do {
        // find and allocate next token
        tokstart = tokend = i;
        while (i < len &&
               !u8_memchr(delim, u8_nextmemchar(s, &i), dlen, &junk))
            tokend = i;
        ssz = tokend - tokstart;
        PUSH(c);  // save previous cons cell
        c = fl_cons(cvalue_string(ssz), NIL);

        // we've done allocation; reload movable pointers
        s = cv_data((cvalue_t*)ptr(args[0]));
        delim = cv_data((cvalue_t*)ptr(args[1]));

        if (ssz) memcpy(cv_data((cvalue_t*)ptr(car_(c))), &s[tokstart], ssz);

        // link new cell
        if (Stack[SP-1] == NIL) {
            Stack[SP-2] = c;   // first time, save first cons
            (void)POP();
        }
        else {
            ((cons_t*)ptr(POP()))->cdr = c;
        }

        // note this tricky condition: if the string ends with a
        // delimiter, we need to go around one more time to add an
        // empty string. this happens when (i==len && tokend<i)
    } while (i < len || (i==len && (tokend!=i)));
    return POP();
}

value_t fl_string_sub(value_t *args, u_int32_t nargs)
{
    argcount("string.sub", nargs, 3);
    char *s = tostring(args[0], "string.sub");
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    size_t i1, i2;
    i1 = toulong(args[1], "string.sub");
    if (i1 > len)
        bounds_error("string.sub", args[0], args[1]);
    i2 = toulong(args[2], "string.sub");
    if (i2 > len)
        bounds_error("string.sub", args[0], args[2]);
    if (i2 <= i1)
        return cvalue_string(0);
    value_t ns = cvalue_string(i2-i1);
    memcpy(cv_data((cvalue_t*)ptr(ns)), &s[i1], i2-i1);
    return ns;
}

value_t fl_string_char(value_t *args, u_int32_t nargs)
{
    argcount("string.char", nargs, 2);
    char *s = tostring(args[0], "string.char");
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    size_t i = toulong(args[1], "string.char");
    if (i >= len)
        bounds_error("string.char", args[0], args[1]);
    size_t sl = u8_seqlen(&s[i]);
    if (sl > len || i > len-sl)
        bounds_error("string.char", args[0], args[1]);
    return mk_wchar(u8_nextchar(s, &i));
}

static value_t mem_find_byte(char *s, char c, size_t start, size_t len)
{
    char *p = memchr(s+start, c, len-start);
    if (p == NULL)
        return FL_F;
    return size_wrap((size_t)(p - s));
}

value_t fl_string_find(value_t *args, u_int32_t nargs)
{
    char cbuf[8];
    size_t start = 0;
    if (nargs == 3)
        start = toulong(args[2], "string.find");
    else
        argcount("string.find", nargs, 2);
    char *s = tostring(args[0], "string.find");
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    if (start > len)
        bounds_error("string.find", args[0], args[2]);
    char *needle; size_t needlesz;

    value_t v = args[1];
    cprim_t *cp = (cprim_t*)ptr(v);
    if (iscprim(v) && cp_class(cp) == wchartype) {
        uint32_t c = *(uint32_t*)cp_data(cp);
        if (c <= 0x7f)
            return mem_find_byte(s, (char)c, start, len);
        needlesz = u8_toutf8(cbuf, sizeof(cbuf), &c, 1);
        needle = cbuf;
    }
    else if (iscprim(v) && cp_class(cp) == bytetype) {
        return mem_find_byte(s, *(char*)cp_data(cp), start, len);
    }
    else if (isstring(v)) {
        cvalue_t *cv = (cvalue_t*)ptr(v);
        needlesz = cv_len(cv);
        needle = (char*)cv_data(cv);
    }
    else {
        type_error("string.find", "string", args[1]);
    }
    if (needlesz > len-start)
        return FL_F;
    else if (needlesz == 1)
        return mem_find_byte(s, needle[0], start, len);
    else if (needlesz == 0)
        return size_wrap(start);
    size_t i;
    for(i=start; i < len-needlesz+1; i++) {
        if (s[i] == needle[0]) {
            if (!memcmp(&s[i+1], needle+1, needlesz-1))
                return size_wrap(i);
        }
    }
    return FL_F;
}

value_t fl_string_inc(value_t *args, u_int32_t nargs)
{
    if (nargs < 2 || nargs > 3)
        argcount("string.inc", nargs, 2);
    char *s = tostring(args[0], "string.inc");
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    size_t i = toulong(args[1], "string.inc");
    size_t cnt = 1;
    if (nargs == 3)
        cnt = toulong(args[2], "string.inc");
    while (cnt--) {
        if (i >= len)
            bounds_error("string.inc", args[0], args[1]);
        (void)(isutf(s[++i]) || isutf(s[++i]) || isutf(s[++i]) || ++i);
    }
    return size_wrap(i);
}

value_t fl_string_dec(value_t *args, u_int32_t nargs)
{
    if (nargs < 2 || nargs > 3)
        argcount("string.dec", nargs, 2);
    char *s = tostring(args[0], "string.dec");
    size_t len = cv_len((cvalue_t*)ptr(args[0]));
    size_t i = toulong(args[1], "string.dec");
    size_t cnt = 1;
    if (nargs == 3)
        cnt = toulong(args[2], "string.dec");
    // note: i is allowed to start at index len
    if (i > len)
        bounds_error("string.dec", args[0], args[1]);
    while (cnt--) {
        if (i == 0)
            bounds_error("string.dec", args[0], args[1]);
        (void)(isutf(s[--i]) || isutf(s[--i]) || isutf(s[--i]) || --i);
    }
    return size_wrap(i);
}

value_t fl_numbertostring(value_t *args, u_int32_t nargs)
{
    if (nargs < 1 || nargs > 2)
        argcount("number->string", nargs, 2);
    value_t n = args[0];
    int neg = 0;
    uint64_t num;
    if (isfixnum(n))      num = numval(n);
    else if (!iscprim(n)) type_error("number->string", "integer", n);
    else num = conv_to_uint64(cp_data((cprim_t*)ptr(n)),
                              cp_numtype((cprim_t*)ptr(n)));
    if (numval(compare(args[0],fixnum(0))) < 0) {
        num = -num;
        neg = 1;
    }
    ulong radix = 10;
    if (nargs == 2) {
        radix = toulong(args[1], "number->string");
        if (radix < 2 || radix > 36)
            lerror(ArgError, "number->string: invalid radix");
    }
    char buf[128];
    char *str = uint2str(buf, sizeof(buf), num, radix);
    if (neg && str > &buf[0])
        *(--str) = '-';
    return string_from_cstr(str);
}

static builtinspec_t stringfunc_info[] = {
    { "string", fl_string },
    { "string?", fl_stringp },
    { "string.count", fl_string_count },
    { "string.split", fl_string_split },
    { "string.sub", fl_string_sub },
    { "string.find", fl_string_find },
    { "string.char", fl_string_char },
    { "string.inc", fl_string_inc },
    { "string.dec", fl_string_dec },
    { "string.reverse", fl_string_reverse },
    { "string.encode", fl_string_encode },
    { "string.decode", fl_string_decode },

    { "number->string", fl_numbertostring },

    { NULL, NULL }
};

void stringfuncs_init()
{
    assign_global_builtins(stringfunc_info);
}