/*******************************************************************************/
/*                                                                             */
/*  XIM support                                                                */
/*                                                                             */
/*  Code courtesy Yin Maofan                                                   */
/*  https://tedyin.com/posts/a-brief-intro-to-linux-input-method-framework/    */
/*                                                                             */
/*******************************************************************************/
#include "unix/guts.h"
#include "Application.h"
void
prima_xim_init(void)
{
        if (
                ( guts.xic_buffer = malloc( guts.xic_bufsize = 256 )) != NULL
        ) {
                char *loc = setlocale(LC_CTYPE, NULL);
                setlocale(LC_CTYPE, "");
                XSetLocaleModifiers("");
                guts.xim = XOpenIM(DISP, NULL, NULL, NULL);
                if ( guts.xim) {
                        guts.xic = XCreateIC(guts.xim, XNInputStyle, XIMPreeditNothing | XIMStatusNothing, NULL);
                        guts.use_xim = true;
                }
                setlocale(LC_CTYPE, loc);
        }
}
void
prima_xim_done(void)
{
        XDestroyIC(guts.xic);
        XCloseIM(guts.xim);
        free(guts.xic_buffer);
        guts.use_xim = false;
}
void
prima_xim_update_cursor( Handle self)
{
        DEFXX;
        XPoint spot;
        XVaNestedList preedit_attr;
        char *error;
        spot.x = XX->cursor_pos.x;
        spot.y = XX->size. y - XX->cursor_pos. y;
        preedit_attr = XVaCreateNestedList(0, XNSpotLocation, &spot, NULL);
        error = XSetICValues(guts.xic, XNPreeditAttributes, preedit_attr, NULL);
        if ( error != NULL )
                Mdebug("XSetICValues(XNSpotLocation) error: %s", error);
        XFree(preedit_attr);
}
void
prima_xim_focus_in(Handle self)
{
        char *error;
        Handle toplevel = prima_find_root_parent(self);
        error = XSetICValues(guts.xic, XNClientWindow, PWidget(toplevel)->handle, NULL);
        if ( error != NULL )
                Mdebug("XSetICValues(XNClientWindow) error: %s", error);
        error = XSetICValues(guts.xic, XNFocusWindow, PWidget(self)->handle, NULL);
        if ( error != NULL )
                Mdebug("XSetICValues(XNFocusWindow) error: %s", error);
        XSetICFocus(guts.xic);
#ifdef X_HAVE_UTF8_STRING
        XFree(Xutf8ResetIC(guts.xic));
#endif
        XCHECKPOINT;
}
void
prima_xim_focus_out(void)
{
        XUnsetICFocus(guts.xic);
        XSetICValues( guts.xic, XNClientWindow, 0, NULL);
        XSetICValues( guts.xic, XNFocusWindow, 0, NULL);
}
Bool
prima_xim_handle_key_press( Handle self, XKeyEvent *xev, Event *e, KeySym *sym)
{
#ifdef X_HAVE_UTF8_STRING
        Status status;
        int c, n;
        Bool ok = true;
        semistatic_t local_buf_ptr;
        char local_buf[256], *buf;
        while ( 1 ) {
                char *b;
                c = Xutf8LookupString(guts.xic, xev, guts.xic_buffer, guts.xic_bufsize - 1, sym, &status);
                Mdebug("Xutf8LookupString: nc=%d status=%d", c, status);
                switch ( status ) {
                case XLookupNone:
                case XLookupKeySym:
                        return false;
                }
                if (status != XBufferOverflow) 
                        break;
                if ( ( b = realloc( guts.xic_buffer, guts.xic_bufsize * 2)) == NULL ) {
                        Mdebug("cannot realloc %d bytes for XIC buffer", guts.xic_bufsize * 2);
                        return false;
                }
                guts.xic_bufsize *= 2;
                guts.xic_buffer = b;
        }
        if ( c == 0 ) return true;
        semistatic_init( &local_buf_ptr, &local_buf, sizeof(char), sizeof(local_buf));
        if ( !semistatic_expand( &local_buf_ptr, c + 1 ))
                return false;
        buf = (char*) local_buf_ptr.heap;
        memcpy( buf, guts.xic_buffer, c);
        guts.xic_buffer[0] = 0;
        buf[c] = 0;
        Mdebug("Xutf8LookupString: string=%s", buf);
        /* send events */
        protect_object(self);
        n = 0;
        while ( *buf ) {
                UV uv;
                unsigned int charlen;
                Event ev;
                uv = prima_utf8_uvchr(buf, c, &charlen);
                buf  += charlen;
                c    -= charlen;
                if ( charlen == 0 ) break;
                n++;
                if ( uv > 0x10FFFF ) continue;
                ev.cmd        = cmKeyDown;
                ev.key.code   = uv;
                ev.key.mod    = kmUnicode;
                ev.key.repeat = 1;
                ev.key.key    = kbNoKey;
                if ( n == 1 && status == XLookupBoth ) {
                        U32 key = prima_keysym_to_keycode(*sym, xev, 0) & kbCodeMask;
                        if ( key != 0 ) ev.key.key = key;
                }
                Mdebug("Xutf8LookupString: char(%d)=%x key=%x", n, uv, ev.key.key);
                CComponent(self)-> message(self,&ev);
                if (PWidget(self)-> stage != csNormal)
                        break;
        }
        unprotect_object(self);
        semistatic_done( &local_buf_ptr);
        XCHECKPOINT;
        return ok;
#else
        return false;
#endif
}