//----------------------------------------------------------------------------//
//                           GNU GPL OS/K                                     //
//                                                                            //
//  Desc:       Buffer library                                                //
//                                                                            //
//                                                                            //
//  Copyright © 2018-2019 The OS/K Team                                       //
//                                                                            //
//  This file is part of OS/K.                                                //
//                                                                            //
//  OS/K is free software: you can redistribute it and/or modify              //
//  it under the terms of the GNU General Public License as published by      //
//  the Free Software Foundation, either version 3 of the License, or         //
//  any later version.                                                        //
//                                                                            //
//  OS/K is distributed in the hope that it will be useful,                   //
//  but WITHOUT ANY WARRANTY//without even the implied warranty of            //
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
//  GNU General Public License for more details.                              //
//                                                                            //
//  You should have received a copy of the GNU General Public License         //
//  along with OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
//----------------------------------------------------------------------------//

#include <kernel/buf.h>

extern error_t bputc(Buffer_t *buf, uchar ch);

//
// Prints formatted string on buf according to fmt
//
error_t BPrintOnBuf(Buffer_t *buf, const char *fmt, ...)
{
    error_t rc;
    va_list ap;

    va_start(ap, fmt);
    rc = BPrintOnBufV(buf, fmt, ap);
    va_end(ap);

    return rc;
}
//
// Prints 0 for octal, 0x for hexadecimal, 0b for binary
//
static error_t bprinthash(Buffer_t *buf, int base, int cap)
{
    error_t rc;

    if (base != 2 && base != 8 && base != 16) {
        return EOK;
    }

    rc = bputc(buf, '0');

    if (!rc && base != 8) {
        rc = bputc(buf, (base==2 ? 'b' : (cap ? 'X' : 'x')));
    }

    return rc;
}

static error_t bdopadding(Buffer_t *buf, size_t width, size_t len,
                          char filler)
{
    error_t rc = EOK;

    for (; !rc && width > len ; width--) {
        rc = bputc(buf, filler);
    }

    return rc;
}

#define bdoconvrt(pref, type, vtype) do {       \
    type i_##type = (type)va_arg(ap, vtype);    \
    pref##toa(i_##type, s, base);               \
} while (0)

// Increase fmt while parsing a modifier
#define fmtnext() do{fmt++;if(*fmt==0){rc=EINVAL;goto leave;}}while(0)

//
// Actually does BPrintOnBuf's job
// Quite a long function
//
error_t BPrintOnBufV(Buffer_t *buf, const char *fmt, va_list ap)
{
    error_t rc = EOK;
    int tmpwidth;
    size_t width;
    char type;

    uchar uch;
    char *s;

    // Conversion buffer
    char convbuf[100];
    size_t len;

    // Flags
    int plus, minus, space, zero, hash;

    // Length modifiers
    int l, h, hh;

    // Signed
    bool sgn;

    // Capital digits
    bool cap;

    // Base
    int base;

    assert(buf && buf->initDone == INITOK);

    if (!buf) return EINVAL;
    if (buf->state != BS_RDWR && buf->state != BS_WRONLY) {
        return EBADF;
    }

    ExAcquireLock(&buf->lock);

//----------------------------------------------------------------------------//

    // We come back here after dealing with a modifier
loop:

    // Deal with all non-'%' characters
    for (; *fmt && *fmt != '%' ; fmt++) {
        rc = bputc(buf, *fmt);
        continue;
    }

    // Job's done / something bad happened
    if (rc || !*fmt) goto leave;

//----------------------------------------------------------------------------//

    //
    // %[parameter][flags][width|*][.precision][length]type
    // We aren't dealing with parameters and float stuff just yet
    //

    // Skip the '%'
    fmtnext();

    // "%%" modifier
    if (*fmt == '%') {
        rc = bputc(buf, '%');

        if (rc > 0) goto leave;
        else {
            fmt++;
            goto loop;
        }
    }

    // Reset everything
    width = 0;
    cap = sgn = 0;
    l = h = hh = 0;
    plus = minus = space = zero = hash = 0;

//----------------------------------------------------------------------------//

    //
    // Flags field
    //
    while (1) {
        if (*fmt == '#') hash++;
        else if (*fmt == '0') zero++;
        else if (*fmt == '+') plus++;
        else if (*fmt == '-') minus++;
        else if (*fmt == ' ') space++;
        else break;
        fmtnext();
    }

//----------------------------------------------------------------------------//

    //
    // Width field
    // A width field of zero is ignored
    //

    // '*' means we should extract it from the argument list
    if (*fmt == '*') {
        fmtnext();
        tmpwidth = va_arg(ap, int);

        // A width below 0 activates the "minus" flag
        if (tmpwidth < 0) {
            width = -tmpwidth;
            minus++;
        } else {
            width = tmpwidth;
        }
    } else {
        // Extract width field from fmt
        while (isdigit(*fmt) && width < sizeof(convbuf)-10) {
            width = 10 * width + (*fmt - '0');
            fmtnext();
        }
    }

    if (width > sizeof(convbuf)) {
        rc = EINVAL;
        goto leave;
    }

//----------------------------------------------------------------------------//

    //
    // Precision field
    // Ignored until floats are implemented
    // TODO before floats: %.XXXs
    //

//----------------------------------------------------------------------------//

    //
    // Length field
    //
    while (1) {
        if (*fmt == 'l' || *fmt == 'z') l++;
        else if (*fmt == 'h') h++;
        else break;
        fmtnext();
    }

    // Consistency check
    assert(!(l > 0 && h > 0));
    assert(!(l > 2 || h > 2));

//----------------------------------------------------------------------------//

    //
    // The type field
    //
    type = *fmt++;

    // Characters
    if (type == 'c') {
        uch = (uchar)va_arg(ap, int);
        bputc(buf, uch);

        goto loop;
    }

    // Strings
    else if (type == 's') {
        s = va_arg(ap, char *);

        if (s == NULL) s = "(null)";

        for (; !rc && *s ; s++) {
            rc = bputc(buf, (uchar)*s);
        }

        if (rc > 0) goto leave;
        goto loop;
    }

    // Decimal, unsigned decimal, hexadecimal, octal and binary numbers
    else if (type == 'd' || type == 'i') { base = 10; sgn = 1; }
    else if (type == 'X') { base = 16; cap = 1; }
    else if (type == 'x') { base = 16; }
    else if (type == 'u') { base = 10; }
    else if (type == 'o') { base = 8; }
    else if (type == 'b') { base = 2; }

    // Pointers: %p = %#012x
    // (48-bit pointers have width 12 at least)
    else if (type == 'p') {
        type = 'x'; base = 16; zero++; hash++; l++;
        if (width < 12) width = 12;
    }

    // Unknown/unsupported modifier
    else {
        rc = EINVAL;
        goto leave;
    }

//----------------------------------------------------------------------------//

    //
    // Numerical conversions
    //

    // We re-use s to iterate convbuf
    s = convbuf;

    if (!l) {
        if (sgn) {
            if (h == 0) bdoconvrt(i, int, int);
            if (h == 1) bdoconvrt(i, short, int);
            if (h == 2) bdoconvrt(i, char, int);
        } else {
            if (h == 0) bdoconvrt(u, uint, uint);
            if (h == 1) bdoconvrt(u, ushort, uint);
            if (h == 2) bdoconvrt(u, uchar, uint);
        }
    }

    else {
        if (sgn) bdoconvrt(l, long, long);
        else bdoconvrt(ul, ulong, ulong);
    }

//----------------------------------------------------------------------------//

    //
    // Implement flags and %X, and prints
    //

    // Capital letter digits
    if (base > 10 && cap) {
        for (; *s ; s++)
            if (islower(*s)) *s = toupper(*s);

        // We use this "opportunity" to compute the length of s
        len = s - convbuf;

        // Reset s
        s = convbuf;
    }
    else len = strlen(s);

    // Adjust width
    if (sgn && (plus || space)) width--;
    else if (hash) width -= (base==8 ? 1 : ((base==2||base==16) ? 2 : 0));

    // When padding with spaces, we pad before +/-'s etc
    if (!minus && !zero && width > len)
        bdopadding(buf, width, len, ' ');

    // Deal with signs and the hash flag
    if (*s == '-') { rc = bputc(buf, '-'); s++, len--; }
    else if (sgn && plus) rc = bputc(buf, '+');
    else if (sgn && space) rc = bputc(buf, ' ');
    else bprinthash(buf, base, cap);

    // Deal with padding by zeroes
    // The 'minus' flag makes no sense with the 'zero' one
    if (zero && width > len)
        bdopadding(buf, width, len, '0');

    //
    // Output the actual number
    //
    for (; !rc && *s ; s++) {
        rc = bputc(buf, (uchar)*s);
    }

    // 'minus' padding, only with spaces
    if (minus && !zero && width > len)
        bdopadding(buf, width, base, ' ');

    if (rc > 0) goto leave;

    // Continue parsing fmt
    goto loop;

//----------------------------------------------------------------------------//

leave:
    ExReleaseLock(&buf->lock);
    return rc;
}