// On-screen Display (ie. console)
// for the Build Engine
// by Jonathon Fowler (jonof@edgenetwk.com)

#include "build.h"
#include "osd.h"
#include "compat.h"
#include "baselayer.h"


typedef struct _symbol {
    const char *name;
    struct _symbol *next;

    const char *help;
    int (*func)(const osdfuncparm_t *);
} symbol_t;

static symbol_t *symbols = NULL;
static symbol_t *addnewsymbol(const char *name);
static symbol_t *findsymbol(const char *name, symbol_t *startingat);
static symbol_t *findexactsymbol(const char *name);

static int _validate_osdlines(void *);

static int _internal_osdfunc_listsymbols(const osdfuncparm_t *);
static int _internal_osdfunc_help(const osdfuncparm_t *);
static int _internal_osdfunc_dumpbuildinfo(const osdfuncparm_t *);
static int _internal_osdfunc_setrendermode(const osdfuncparm_t *);

static int white=-1;			// colour of white (used by default display routines)
static void _internal_drawosdchar(int, int, char, int, int);
static void _internal_drawosdstr(int, int, char*, int, int, int);
static void _internal_drawosdcursor(int,int,int,int);
static int _internal_getcolumnwidth(int);
static int _internal_getrowheight(int);
static void _internal_clearbackground(int,int);
static int _internal_gettime(void);
static void _internal_onshowosd(int);

#define TEXTSIZE 16384

// history display
static char osdtext[TEXTSIZE];
static int  osdpos=0;			// position next character will be written at
static int  osdlines=1;			// # lines of text in the buffer
static int  osdrows=20;			// # lines of the buffer that are visible
static int  osdcols=60;			// width of onscreen display in text columns
static int  osdmaxrows=20;		// maximum number of lines which can fit on the screen
static int  osdmaxlines=TEXTSIZE/60;	// maximum lines which can fit in the buffer
static char osdvisible=0;		// onscreen display visible?
static int  osdhead=0; 			// topmost visible line number
static BFILE *osdlog=NULL;		// log filehandle
static char osdinited=0;		// text buffer initialised?
static int  osdkey=0x45;		// numlock shows the osd
static int  keytime=0;

// command prompt editing
#define EDITLENGTH 512
static int  osdovertype=0;		// insert (0) or overtype (1)
static char osdeditbuf[EDITLENGTH+1];	// editing buffer
static char osdedittmp[EDITLENGTH+1];	// editing buffer temporary workspace
static int  osdeditlen=0;		// length of characters in edit buffer
static int  osdeditcursor=0;		// position of cursor in edit buffer
static int  osdeditshift=0;		// shift state
static int  osdeditcontrol=0;		// control state
static int  osdeditcaps=0;		// capslock
static int  osdeditwinstart=0;
static int  osdeditwinend=60-1-3;
#define editlinewidth (osdcols-1-3)

// command processing
#define HISTORYDEPTH 16
static int  osdhistorypos=-1;		// position we are at in the history buffer
static int  osdhistorybuf[HISTORYDEPTH][EDITLENGTH+1];	// history strings
static int  osdhistorysize=0;		// number of entries in history

// execution buffer
// the execution buffer works from the command history
static int  osdexeccount=0;		// number of lines from the head of the history buffer to execute

// presentation parameters
static int  osdpromptshade=0;
static int  osdpromptpal=0;
static int  osdeditshade=0;
static int  osdeditpal=0;
static int  osdtextshade=0;
static int  osdtextpal=0;
static int  osdcursorshade=0;
static int  osdcursorpal=0;

// application callbacks
static void (*drawosdchar)(int, int, char, int, int) = _internal_drawosdchar;
static void (*drawosdstr)(int, int, char*, int, int, int) = _internal_drawosdstr;
static void (*drawosdcursor)(int, int, int, int) = _internal_drawosdcursor;
static int (*getcolumnwidth)(int) = _internal_getcolumnwidth;
static int (*getrowheight)(int) = _internal_getrowheight;
static void (*clearbackground)(int,int) = _internal_clearbackground;
static int (*gettime)(void) = _internal_gettime;
static void (*onshowosd)(int) = _internal_onshowosd;


static void _internal_drawosdchar(int x, int y, char ch, int shade, int pal)
{
    int i,j,k;
    char st[2] = { 0,0 };

    st[0] = ch;

    if (white<0) {
        // find the palette index closest to white
        k=0;
        for(i=0;i<256;i++)
        {
            j = ((int)curpalette[i].r)+((int)curpalette[i].g)+((int)curpalette[i].b);
            if (j > k) { k = j; white = i; }
        }
    }

    printext256(4+(x<<3),4+(y<<3), white, -1, st, 0);
}

static void _internal_drawosdstr(int x, int y, char *ch, int len, int shade, int pal)
{
    int i,j,k;
    char st[1024];

    if (len>1023) len=1023;
    memcpy(st,ch,len);
    st[len]=0;

    if (white<0) {
        // find the palette index closest to white
        k=0;
        for(i=0;i<256;i++)
        {
            j = ((int)curpalette[i].r)+((int)curpalette[i].g)+((int)curpalette[i].b);
            if (j > k) { k = j; white = i; }
        }
    }

    printext256(4+(x<<3),4+(y<<3), white, -1, st, 0);
}

static void _internal_drawosdcursor(int x, int y, int type, int lastkeypress)
{
    int i,j,k;
    char st[2] = { '_',0 };

    if (type) st[0] = '#';

    if (white<0) {
        // find the palette index closest to white
        k=0;
        for(i=0;i<256;i++)
        {
            j = ((int)palette[i*3])+((int)palette[i*3+1])+((int)palette[i*3+2]);
            if (j > k) { k = j; white = i; }
        }
    }

    printext256(4+(x<<3),4+(y<<3)+2, white, -1, st, 0);
}

static int _internal_getcolumnwidth(int w)
{
    return w/8 - 1;
}

static int _internal_getrowheight(int w)
{
    return w/8;
}

static void _internal_clearbackground(int cols, int rows)
{
}

static int _internal_gettime(void)
{
    return 0;
}

static void _internal_onshowosd(int a)
{
}

////////////////////////////

static int _internal_osdfunc_vars(const osdfuncparm_t *parm)
{
    int showval = (parm->numparms < 1);

    if (!Bstrcasecmp(parm->name, "osdrows")) {
        if (showval) { OSD_Printf("osdrows is %d\n", osdrows); return OSDCMD_OK; }
        else {
            osdrows = atoi(parm->parms[0]);
            if (osdrows < 1) osdrows = 1;
            else if (osdrows > osdmaxrows) osdrows = osdmaxrows;
            return OSDCMD_OK;
        }
    }
    return OSDCMD_SHOWHELP;
}

static int _internal_osdfunc_listsymbols(const osdfuncparm_t *parm)
{
    symbol_t *i;

    OSD_Printf("Symbol listing:\n");
    for (i=symbols; i!=NULL; i=i->next)
        OSD_Printf("     %s\n", i->name);

    return OSDCMD_OK;
}

static int _internal_osdfunc_help(const osdfuncparm_t *parm)
{
    symbol_t *symb;

    if (parm->numparms != 1) return OSDCMD_SHOWHELP;
    symb = findexactsymbol(parm->parms[0]);
    if (!symb) {
        OSD_Printf("Help Error: \"%s\" is not a defined variable or function\n", parm->parms[0]);
    } else {
        OSD_Printf("%s\n", symb->help);
    }

    return OSDCMD_OK;
}



////////////////////////////


//
// OSD_Cleanup() -- Cleans up the on-screen display
//
void OSD_Cleanup(void)
{
    symbol_t *s;

    for (; symbols; symbols=s) {
        s=symbols->next;
        Bfree(symbols);
    }

    if (osdlog) Bfclose(osdlog);
    osdlog = NULL;

    osdinited=0;
}


//
// OSD_Init() -- Initialises the on-screen display
//
void OSD_Init(void)
{
    Bmemset(osdtext, 32, TEXTSIZE);
    osdlines=1;

    osdinited=1;

    OSD_RegisterFunction("listsymbols","listsymbols: lists all the recognized symbols",_internal_osdfunc_listsymbols);
    OSD_RegisterFunction("help","help: displays help on the named symbol",_internal_osdfunc_help);
    OSD_RegisterFunction("osdrows","osdrows: sets the number of visible lines of the OSD",_internal_osdfunc_vars);

    atexit(OSD_Cleanup);
}


//
// OSD_SetLogFile() -- Sets the text file where printed text should be echoed
//
void OSD_SetLogFile(char *fn)
{
    if (osdlog) Bfclose(osdlog);
    osdlog = NULL;
    if (fn) osdlog = Bfopen(fn,"w");
    if (osdlog) setvbuf(osdlog, (char*)NULL, _IONBF, 0);
}


//
// OSD_SetFunctions() -- Sets some callbacks which the OSD uses to understand its world
//
void OSD_SetFunctions(
    void (*drawchar)(int,int,char,int,int),
    void (*drawstr)(int,int,char*,int,int,int),
    void (*drawcursor)(int,int,int,int),
    int (*colwidth)(int),
    int (*rowheight)(int),
    void (*clearbg)(int,int),
    int (*gtime)(void),
    void (*showosd)(int)
)
{
    drawosdchar = drawchar;
    drawosdstr = drawstr;
    drawosdcursor = drawcursor;
    getcolumnwidth = colwidth;
    getrowheight = rowheight;
    clearbackground = clearbg;
    gettime = gtime;
    onshowosd = showosd;

    if (!drawosdchar) drawosdchar = _internal_drawosdchar;
    if (!drawosdstr) drawosdstr = _internal_drawosdstr;
    if (!drawosdcursor) drawosdcursor = _internal_drawosdcursor;
    if (!getcolumnwidth) getcolumnwidth = _internal_getcolumnwidth;
    if (!getrowheight) getrowheight = _internal_getrowheight;
    if (!clearbackground) clearbackground = _internal_clearbackground;
    if (!gettime) gettime = _internal_gettime;
    if (!onshowosd) onshowosd = _internal_onshowosd;
}


//
// OSD_SetParameters() -- Sets the parameters for presenting the text
//
void OSD_SetParameters(
    int promptshade, int promptpal,
    int editshade, int editpal,
    int textshade, int textpal
)
{
    osdpromptshade = promptshade;
    osdpromptpal   = promptpal;
    osdeditshade   = editshade;
    osdeditpal     = editpal;
    osdtextshade   = textshade;
    osdtextpal     = textpal;
}


//
// OSD_CaptureKey() -- Sets the scancode for the key which activates the onscreen display
//
void OSD_CaptureKey(int sc)
{
    osdkey = sc;
}


//
// OSD_HandleKey() -- Handles keyboard input when capturing input.
// 	Returns 0 if the key was handled internally, or the scancode if it should
// 	be passed on to the game.
//
int OSD_HandleKey(int sc, int press)
{
    char ch;
    int i,j;
    symbol_t *tabc = NULL;
    static symbol_t *lastmatch = NULL;

    if (!osdinited) return sc;

    if (sc == osdkey) {
        if (press) {
            OSD_ShowDisplay(osdvisible ^ 1);
            bflushchars();
        }
        return 0;//sc;
    } else if (!osdvisible) {
        return sc;
    }

    if (!press) {
        if (sc == 42 || sc == 54) // shift
            osdeditshift = 0;
        if (sc == 29 || sc == 157)	// control
            osdeditcontrol = 0;
        return 0;//sc;
    }

    keytime = gettime();

    if (sc != 15) lastmatch = NULL;		// tab

    while ( (ch = bgetchar()) ) {
        if (ch == 1) {	// control a. jump to beginning of line
        } else if (ch == 2) {	// control b, move one character left
        } else if (ch == 5) {	// control e, jump to end of line
        } else if (ch == 6) {	// control f, move one character right
        } else if (ch == 8 || ch == 127) {	// control h, backspace
            if (!osdeditcursor || !osdeditlen) return 0;
            if (!osdovertype) {
                if (osdeditcursor < osdeditlen)
                    Bmemmove(osdeditbuf+osdeditcursor-1, osdeditbuf+osdeditcursor, osdeditlen-osdeditcursor);
                osdeditlen--;
            }
            osdeditcursor--;
            if (osdeditcursor<osdeditwinstart) osdeditwinstart--,osdeditwinend--;
        } else if (ch == 9) {	// tab
            if (!lastmatch) {
                for (i=osdeditcursor;i>0;i--) if (osdeditbuf[i-1] == ' ') break;
                for (j=0;osdeditbuf[i] != ' ' && i < osdeditlen;j++,i++)
                    osdedittmp[j] = osdeditbuf[i];
                osdedittmp[j] = 0;

                if (j > 0)
                    tabc = findsymbol(osdedittmp, NULL);
            } else {
                tabc = findsymbol(osdedittmp, lastmatch->next);
                if (!tabc && lastmatch)
                    tabc = findsymbol(osdedittmp, NULL);	// wrap
            }

            if (tabc) {
                for (i=osdeditcursor;i>0;i--) if (osdeditbuf[i-1] == ' ') break;
                osdeditlen = i;
                for (j=0;tabc->name[j] && osdeditlen <= EDITLENGTH;i++,j++,osdeditlen++)
                    osdeditbuf[i] = tabc->name[j];
                osdeditcursor = osdeditlen;
                osdeditwinend = osdeditcursor;
                osdeditwinstart = osdeditwinend-editlinewidth;
                if (osdeditwinstart<0) {
                    osdeditwinstart=0;
                    osdeditwinend = editlinewidth;
                }

                lastmatch = tabc;
            }
        } else if (ch == 11) {	// control k, delete all to end of line
        } else if (ch == 12) {	// control l, clear screen
        } else if (ch == 13) {	// control m, enter
            if (osdeditlen>0) {
                osdeditbuf[osdeditlen] = 0;
                Bmemmove(osdhistorybuf[1], osdhistorybuf[0], HISTORYDEPTH*(EDITLENGTH+1));
                Bmemmove(osdhistorybuf[0], osdeditbuf, EDITLENGTH+1);
                if (osdhistorysize < HISTORYDEPTH) osdhistorysize++;
                if (osdexeccount == HISTORYDEPTH)
                    OSD_Printf("Command Buffer Warning: Failed queueing command "
                               "for execution. Buffer full.\n");
                else
                    osdexeccount++;
                osdhistorypos=-1;
            }

            osdeditlen=0;
            osdeditcursor=0;
            osdeditwinstart=0;
            osdeditwinend=editlinewidth;
        } else if (ch == 16) {	// control p, previous (ie. up arrow)
        } else if (ch == 20) {	// control t, swap previous two chars
        } else if (ch == 21) {	// control u, delete all to beginning
            if (osdeditcursor>0 && osdeditlen) {
                if (osdeditcursor<osdeditlen)
                    Bmemmove(osdeditbuf, osdeditbuf+osdeditcursor, osdeditlen-osdeditcursor);
                osdeditlen-=osdeditcursor;
                osdeditcursor = 0;
                osdeditwinstart = 0;
                osdeditwinend = editlinewidth;
            }
        } else if (ch == 23) {	// control w, delete one word back
            if (osdeditcursor>0 && osdeditlen>0) {
                i=osdeditcursor;
                while (i>0 && osdeditbuf[i-1]==32) i--;
                while (i>0 && osdeditbuf[i-1]!=32) i--;
                if (osdeditcursor<osdeditlen)
                    Bmemmove(osdeditbuf+i, osdeditbuf+osdeditcursor, osdeditlen-osdeditcursor);
                osdeditlen -= (osdeditcursor-i);
                osdeditcursor = i;
                if (osdeditcursor < osdeditwinstart) {
                    osdeditwinstart=osdeditcursor;
                    osdeditwinend=osdeditwinstart+editlinewidth;
                }
            }
        } else if (ch >= 32) {	// text char
            if (!osdovertype && osdeditlen == EDITLENGTH)	// buffer full, can't insert another char
                return 0;

            if (!osdovertype) {
                if (osdeditcursor < osdeditlen)
                    Bmemmove(osdeditbuf+osdeditcursor+1, osdeditbuf+osdeditcursor, osdeditlen-osdeditcursor);
                osdeditlen++;
            } else {
                if (osdeditcursor == osdeditlen)
                    osdeditlen++;
            }
            osdeditbuf[osdeditcursor] = ch;
            osdeditcursor++;
            if (osdeditcursor>osdeditwinend) osdeditwinstart++,osdeditwinend++;
        }
    }

    if (sc == 15) {		// tab
    } else if (sc == 1) {		// escape
        OSD_ShowDisplay(0);
    } else if (sc == 201) {	// page up
        if (osdhead < osdlines-1)
            osdhead++;
    } else if (sc == 209) {	// page down
        if (osdhead > 0)
            osdhead--;
    } else if (sc == 199) {	// home
        if (osdeditcontrol) {
            osdhead = osdlines-1;
        } else {
            osdeditcursor = 0;
            osdeditwinstart = osdeditcursor;
            osdeditwinend = osdeditwinstart+editlinewidth;
        }
    } else if (sc == 207) {	// end
        if (osdeditcontrol) {
            osdhead = 0;
        } else {
            osdeditcursor = osdeditlen;
            osdeditwinend = osdeditcursor;
            osdeditwinstart = osdeditwinend-editlinewidth;
            if (osdeditwinstart<0) {
                osdeditwinstart=0;
                osdeditwinend = editlinewidth;
            }
        }
    } else if (sc == 210) {	// insert
        osdovertype ^= 1;
    } else if (sc == 203) {	// left
        if (osdeditcursor>0) {
            if (osdeditcontrol) {
                while (osdeditcursor>0) {
                    if (osdeditbuf[osdeditcursor-1] != 32) break;
                    osdeditcursor--;
                }
                while (osdeditcursor>0) {
                    if (osdeditbuf[osdeditcursor-1] == 32) break;
                    osdeditcursor--;
                }
            } else osdeditcursor--;
        }
        if (osdeditcursor<osdeditwinstart)
            osdeditwinend-=(osdeditwinstart-osdeditcursor),
                           osdeditwinstart-=(osdeditwinstart-osdeditcursor);
    } else if (sc == 205) {	// right
        if (osdeditcursor<osdeditlen) {
            if (osdeditcontrol) {
                while (osdeditcursor<osdeditlen) {
                    if (osdeditbuf[osdeditcursor] == 32) break;
                    osdeditcursor++;
                }
                while (osdeditcursor<osdeditlen) {
                    if (osdeditbuf[osdeditcursor] != 32) break;
                    osdeditcursor++;
                }
            } else osdeditcursor++;
        }
        if (osdeditcursor>=osdeditwinend)
            osdeditwinstart+=(osdeditcursor-osdeditwinend),
                             osdeditwinend+=(osdeditcursor-osdeditwinend);
    } else if (sc == 200) {	// up
        if (osdhistorypos < osdhistorysize-1) {
            osdhistorypos++;
            memcpy(osdeditbuf, osdhistorybuf[osdhistorypos], EDITLENGTH+1);
            osdeditlen = osdeditcursor = 0;
            while (osdeditbuf[osdeditcursor]) osdeditlen++, osdeditcursor++;
            if (osdeditcursor<osdeditwinstart) {
                osdeditwinend = osdeditcursor;
                osdeditwinstart = osdeditwinend-editlinewidth;

                if (osdeditwinstart<0)
                    osdeditwinend-=osdeditwinstart,
                                   osdeditwinstart=0;
            } else if (osdeditcursor>=osdeditwinend)
                osdeditwinstart+=(osdeditcursor-osdeditwinend),
                                 osdeditwinend+=(osdeditcursor-osdeditwinend);
        }
    } else if (sc == 208) {	// down
        if (osdhistorypos >= 0) {
            if (osdhistorypos == 0) {
                osdeditlen=0;
                osdeditcursor=0;
                osdeditwinstart=0;
                osdeditwinend=editlinewidth;
                osdhistorypos = -1;
            } else {
                osdhistorypos--;
                memcpy(osdeditbuf, osdhistorybuf[osdhistorypos], EDITLENGTH+1);
                osdeditlen = osdeditcursor = 0;
                while (osdeditbuf[osdeditcursor]) osdeditlen++, osdeditcursor++;
                if (osdeditcursor<osdeditwinstart) {
                    osdeditwinend = osdeditcursor;
                    osdeditwinstart = osdeditwinend-editlinewidth;

                    if (osdeditwinstart<0)
                        osdeditwinend-=osdeditwinstart,
                                       osdeditwinstart=0;
                } else if (osdeditcursor>=osdeditwinend)
                    osdeditwinstart+=(osdeditcursor-osdeditwinend),
                                     osdeditwinend+=(osdeditcursor-osdeditwinend);
            }
        }
    } else if (sc == 42 || sc == 54) {	// shift
        osdeditshift = 1;
    } else if (sc == 29 || sc == 157) {	// control
        osdeditcontrol = 1;
    } else if (sc == 58) {	// capslock
        osdeditcaps ^= 1;
    } else if (sc == 28 || sc == 156) {	// enter
    } else if (sc == 14) {		// backspace
    } else if (sc == 211) {	// delete
        if (osdeditcursor == osdeditlen || !osdeditlen) return 0;
        if (osdeditcursor <= osdeditlen-1) Bmemmove(osdeditbuf+osdeditcursor, osdeditbuf+osdeditcursor+1, osdeditlen-osdeditcursor-1);
        osdeditlen--;
    }

    return 0;
}


//
// OSD_ResizeDisplay() -- Handles readjustment of the display when the screen resolution
// 	changes on us.
//
void OSD_ResizeDisplay(int w, int h)
{
    int newcols;
    int newmaxlines;
    char newtext[TEXTSIZE];
    int i,j,k;

    newcols = getcolumnwidth(w);
    newmaxlines = TEXTSIZE / newcols;

    j = min(newmaxlines, osdmaxlines);
    k = min(newcols, osdcols);

    memset(newtext, 32, TEXTSIZE);
    for (i=0;i<j;i++) {
        memcpy(newtext+newcols*i, osdtext+osdcols*i, k);
    }

    memcpy(osdtext, newtext, TEXTSIZE);
    osdcols = newcols;
    osdmaxlines = newmaxlines;
    osdmaxrows = getrowheight(h)-2;

    if (osdrows > osdmaxrows) osdrows = osdmaxrows;

    osdpos = 0;
    osdhead = 0;
    osdeditwinstart = 0;
    osdeditwinend = editlinewidth;
    white = -1;
}


//
// OSD_ShowDisplay() -- Shows or hides the onscreen display
//
void OSD_ShowDisplay(int onf)
{
    osdvisible = (onf != 0);
    osdeditcontrol = 0;
    osdeditshift = 0;

    grabmouse(osdvisible == 0);
    onshowosd(osdvisible);
    if (osdvisible) releaseallbuttons();
}


//
// OSD_Draw() -- Draw the onscreen display
//
void OSD_Draw(void)
{
    unsigned topoffs;
    int row, lines, x, len;

    if (!osdvisible || !osdinited) return;

    topoffs = osdhead * osdcols;
    row = osdrows-1;
    lines = min( osdlines-osdhead, osdrows );

    begindrawing();

    clearbackground(osdcols,osdrows+1);

    for (; lines>0; lines--, row--) {
        drawosdstr(0,row,osdtext+topoffs,osdcols,osdtextshade,osdtextpal);
        topoffs+=osdcols;
    }

    drawosdchar(2,osdrows,'>',osdpromptshade,osdpromptpal);
    if (osdeditcaps) drawosdchar(0,osdrows,'C',osdpromptshade,osdpromptpal);
    if (osdeditshift) drawosdchar(1,osdrows,'H',osdpromptshade,osdpromptpal);

    len = min(osdcols-1-3, osdeditlen-osdeditwinstart);
    for (x=0; x<len; x++)
        drawosdchar(3+x,osdrows,osdeditbuf[osdeditwinstart+x],osdeditshade,osdeditpal);

    drawosdcursor(3+osdeditcursor-osdeditwinstart,osdrows,osdovertype,keytime);

    enddrawing();
}


//
// OSD_Printf() -- Print a string to the onscreen display
//   and write it to the log file
//

static inline void linefeed(void)
{
    Bmemmove(osdtext+osdcols, osdtext, TEXTSIZE-osdcols);
    Bmemset(osdtext, 32, osdcols);

    if (osdlines < osdmaxlines) osdlines++;
}

void OSD_Printf(const char *fmt, ...)
{
    char tmpstr[1024], *chp;
    va_list va;

    if (!osdinited) OSD_Init();

    va_start(va, fmt);
    Bvsnprintf(tmpstr, 1024, fmt, va);
    va_end(va);

    if (osdlog) Bfputs(tmpstr, osdlog);

    for (chp = tmpstr; *chp; chp++) {
        if (*chp == '\r') osdpos=0;
        else if (*chp == '\n') {
            osdpos=0;
            linefeed();
        } else {
            osdtext[osdpos++] = *chp;
            if (osdpos == osdcols) {
                osdpos = 0;
                linefeed();
            }
        }
    }
}


//
// OSD_DispatchQueued() -- Executes any commands queued in the buffer
//
void OSD_DispatchQueued(void)
{
    int cmd;

    if (!osdexeccount) return;

    cmd=osdexeccount-1;
    osdexeccount=0;

    for (; cmd>=0; cmd--) {
        OSD_Dispatch((const char *)osdhistorybuf[cmd]);
    }
}


//
// OSD_Dispatch() -- Executes a command string
//

static char *strtoken(char *s, char **ptrptr, int *restart)
{
    char *p, *p2, *start;

    *restart = 0;
    if (!ptrptr) return NULL;

    // if s != NULL, we process from the start of s, otherwise
    // we just continue with where ptrptr points to
    if (s) p = s;
    else p = *ptrptr;

    if (!p) return NULL;

    // eat up any leading whitespace
    while (*p != 0 && *p != ';' && *p == ' ') p++;

    // a semicolon is an end of statement delimiter like a \0 is, so we signal
    // the caller to 'restart' for the rest of the string pointed at by *ptrptr
    if (*p == ';') {
        *restart = 1;
        *ptrptr = p+1;
        return NULL;
    }
    // or if we hit the end of the input, signal all done by nulling *ptrptr
    else if (*p == 0) {
        *ptrptr = NULL;
        return NULL;
    }

    if (*p == '\"') {
        // quoted string
        start = ++p;
        p2 = p;
        while (*p != 0) {
            if (*p == '\"') {
                p++;
                break;
            } else if (*p == '\\') {
                switch (*(++p)) {
                case 'n': *p2 = '\n'; break;
                case 'r': *p2 = '\r'; break;
                default: *p2 = *p; break;
                }
            } else {
                *p2 = *p;
            }
            p2++, p++;
        }
        *p2 = 0;
    } else {
        start = p;
        while (*p != 0 && *p != ';' && *p != ' ') p++;
    }

    // if we hit the end of input, signal all done by nulling *ptrptr
    if (*p == 0) {
        *ptrptr = NULL;
    }
    // or if we came upon a semicolon, signal caller to restart with the
    // string at *ptrptr
    else if (*p == ';') {
        *p = 0;
        *ptrptr = p+1;
        *restart = 1;
    }
    // otherwise, clip off the token and carry on
    else {
        *(p++) = 0;
        *ptrptr = p;
    }

    return start;
}

#define MAXPARMS 512
int OSD_Dispatch(const char *cmd)
{
    char *workbuf, *wp, *wtp, *state;
    char *parms[MAXPARMS];
    int  numparms, restart = 0;
    osdfuncparm_t ofp;
    symbol_t *symb;
    //int i;

    workbuf = state = Bstrdup(cmd);
    if (!workbuf) return -1;

    do {
        numparms = 0;
        Bmemset(parms, 0, sizeof(parms));
        wp = strtoken(state, &wtp, &restart);
        if (!wp) {
            state = wtp;
            continue;
        }

        symb = findexactsymbol(wp);
        if (!symb) {
            OSD_Printf("Error: \"%s\" is not defined\n", wp);
            free(workbuf);
            return -1;
        }

        ofp.name = wp;
        while (wtp && !restart) {
            wp = strtoken(NULL, &wtp, &restart);
            if (wp && numparms < MAXPARMS) parms[numparms++] = wp;
        }
        ofp.numparms = numparms;
        ofp.parms    = (const char **)parms;
        ofp.raw      = cmd;
        switch (symb->func(&ofp)) {
        case OSDCMD_OK: break;
        case OSDCMD_SHOWHELP: OSD_Printf("%s\n", symb->help); break;
        }

        state = wtp;
    } while (wtp && restart);

    free(workbuf);

    return 0;
}


//
// OSD_RegisterFunction() -- Registers a new function
//
int OSD_RegisterFunction(const char *name, const char *help, int (*func)(const osdfuncparm_t*))
{
    symbol_t *symb;
    const char *cp;

    if (!osdinited) OSD_Init();

    if (!name) {
        Bprintf("OSD_RegisterFunction(): may not register a function with a null name\n");
        return -1;
    }
    if (!name[0]) {
        Bprintf("OSD_RegisterFunction(): may not register a function with no name\n");
        return -1;
    }

    // check for illegal characters in name
    for (cp = name; *cp; cp++) {
        if ((cp == name) && (*cp >= '0') && (*cp <= '9')) {
            Bprintf("OSD_RegisterFunction(): first character of function name \"%s\" must not be a numeral\n", name);
            return -1;
        }
        if ((*cp < '0') ||
                (*cp > '9' && *cp < 'A') ||
                (*cp > 'Z' && *cp < 'a' && *cp != '_') ||
                (*cp > 'z')) {
            Bprintf("OSD_RegisterFunction(): illegal character in function name \"%s\"\n", name);
            return -1;
        }
    }

    if (!help) help = "(no description for this function)";
    if (!func) {
        Bprintf("OSD_RegisterFunction(): may not register a null function\n");
        return -1;
    }

    symb = findexactsymbol(name);
    if (symb) {
        Bprintf("OSD_RegisterFunction(): \"%s\" is already defined\n", name);
        return -1;
    }

    symb = addnewsymbol(name);
    if (!symb) {
        Bprintf("OSD_RegisterFunction(): Failed registering function \"%s\"\n", name);
        return -1;
    }

    symb->name = name;
    symb->help = help;
    symb->func = func;

    return 0;
}


//
// addnewsymbol() -- Allocates space for a new symbol and attaches it
//   appropriately to the lists, sorted.
//
static symbol_t *addnewsymbol(const char *name)
{
    symbol_t *newsymb, *s, *t;

    newsymb = (symbol_t *)Bmalloc(sizeof(symbol_t));
    if (!newsymb) { return NULL; }
    Bmemset(newsymb, 0, sizeof(symbol_t));

    // link it to the main chain
    if (!symbols) {
        symbols = newsymb;
    } else {
        if (Bstrcasecmp(name, symbols->name) <= 0) {
            t = symbols;
            symbols = newsymb;
            symbols->next = t;
        } else {
            s = symbols;
            while (s->next) {
                if (Bstrcasecmp(s->next->name, name) > 0) break;
                s=s->next;
            }
            t = s->next;
            s->next = newsymb;
            newsymb->next = t;
        }
    }

    return newsymb;
}


//
// findsymbol() -- Finds a symbol, possibly partially named
//
static symbol_t *findsymbol(const char *name, symbol_t *startingat)
{
    if (!startingat) startingat = symbols;
    if (!startingat) return NULL;

    for (; startingat; startingat=startingat->next)
        if (!Bstrncasecmp(name, startingat->name, Bstrlen(name))) return startingat;

    return NULL;
}


//
// findexactsymbol() -- Finds a symbol, complete named
//
static symbol_t *findexactsymbol(const char *name)
{
    symbol_t *startingat;
    if (!symbols) return NULL;

    startingat = symbols;

    for (; startingat; startingat=startingat->next)
        if (!Bstrcasecmp(name, startingat->name)) return startingat;

    return NULL;
}