//----------------------------------------------------------------------------//
//                           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 <lib/buf.h>

#ifdef _KALEID_KERNEL
#include <io/vga.h>
#endif

//
// 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);
    ExAcquireLock(&buf->lock);
    rc = vbprintf(buf, fmt, ap);
    ExReleaseLock(&buf->lock);
    va_end(ap);

    return rc;
}

error_t BPrintOnBufV(Buffer_t *buf, const char *fmt, va_list ap)
{
    error_t rc;
    
    ExAcquireLock(&buf->lock);
    rc = vbprintf(buf, fmt, ap);
    ExReleaseLock(&buf->lock);
    
    return rc;
}

error_t bprintf(Buffer_t *buf, const char *fmt, ...)
{
    error_t rc;
    va_list ap;

    va_start(ap, fmt);
    rc = vbprintf(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 CONVBUFSIZE 100

//
// Actually does BPrintOnBuf's job; doesn't lock anything
// Quite a long function
//
error_t vbprintf(Buffer_t *buf, const char *fmt, va_list ap)
{
    error_t rc = 0;

    int width, prec, len;
    char type;

    uchar uch;
    char *s;

    // Conversion buffer
    char convbuf[CONVBUFSIZE];

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

    // Length modifiers
    int l, h, hh;

    // Signed
    bool sgn;

    // Capital digits
    bool cap;

    // Base
    int base;

    if (!buf || !fmt) return EINVAL;
    if (buf->flags & (BF_EOF|BF_ERR)) return EENDF;
    if (buf->state != BS_RDWR && buf->state != BS_WRONLY) {
        return EBADF;
    }

    // Progress in format string
    while (*fmt && !rc) {

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

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

        // Skip the '%'
        fmt++;

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

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

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

        //
        // Width & precision fields
        // A width field of zero is ignored
        //

        // Extracts either width or precision
        #define bextractwp(name)                                        \
        do {                                                            \
            if (*fmt == '*') {                                          \
                fmt++;                                                  \
                name = va_arg(ap, int);                                 \
            } else {                                                    \
                while (isdigit(*fmt) && name < CONVBUFSIZE) {           \
                    name = 10 * name + (*fmt - '0');                    \
                    fmt++;                                              \
                }                                                       \
            }                                                           \
        } while (0)
        
        // Extract width
        bextractwp(width);

        // A width below 0 activates the "minus" flag
        if (width < 0) {
            width = -width;
            minus++;
        }
        
        // Extract precision
        if (*fmt == '.') {
            fmt++;
            bextractwp(prec);
        }

        // Make sure they're not too big
        if (width > CONVBUFSIZE || prec > CONVBUFSIZE) {
            rc = EINVAL;
            break;
        }

        //
        // Length field
        //

        while (*fmt) {
            if (*fmt == 'l' || *fmt == 'z' || *fmt == 't') {
                fmt++;
                l++;
            }

            else if (*fmt == 'h') {
                fmt++;
                h++;
            }
            
            // Next field
            else break;
        }

        // Consistency check
        assert(!(l > 0 && h > 0));
        assert(!(l > 2 || h > 1));

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

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

            continue;
        }

#ifdef _KALEID_KERNEL
        if (type == 'C') {
            base = va_arg(ap, int);
            
            if (!(base < 0 || base > VGA_COLOR_WHITE))
                rc = bputc(buf, RtlColorToChar(base));
            
            continue;
        }
#endif

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

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

            // For strings, the precision field gives the maximum
            // amount of characters to be read from the stream
            // Zero/nonspecified precision means unlimited amount
            if (prec == 0) prec = INT_MAX;
            
            for (; *s && prec-- ; s++) {
                rc = bputc(buf, (uchar)*s);
            }

            continue;
        }

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

        // End of string too soon
        else if (type == '\0') {
            bputc(buf, '%');
            rc = EINVAL;
            break;
        }

        // Unknown/unsupported modifier
        else {
            bputc(buf, '%');
            bputc(buf, '?');
            rc = bputc(buf, type);
            continue;
        }

        //
        // Numerical conversions
        //

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

        // FIXME: this works, but is ugly as hell
        #define bdoconvrt(pref, type, vtype)                    \
            do {                                                \
                type i_##type = (type)va_arg(ap, vtype);        \
                pref##toa(i_##type, s, base);                   \
            } while (0)

        if (!l) {
            if (sgn) {
                if (h == 0) bdoconvrt(i, int, int);
                if (h == 1) bdoconvrt(i, short, int);
            } else {
                if (h == 0) bdoconvrt(u, uint, uint);
                if (h == 1) bdoconvrt(u, ushort, 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;
        }
        
        // Compute s's length
        // It will always fit in an int
        else len = (int)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 if (hash) 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, ' ');
            
        // Carry on to next modifier
   }
   
   // For debugging purposes
   assert(!rc);

   return rc;
}