#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <gtk/gtk.h>
#ifdef GDK_WINDOWING_X11
#include <gdk/gdkx.h>
#endif
#include "ipc.h"

typedef struct Im Im;
struct Im
{
	GtkIMContext parent;
	int fd;
	int usepreedit;
	int effective;
	int ext;
	int private;
	char pre[Ipcfieldmax+1];
	int prelen;
	GdkWindow *win;
	GdkRectangle cursor;
	int cursorvalid;
	int caretsent;
	int sentvalid;
	int32_t sentx;
	int32_t senty;
	int32_t senth;
};

typedef struct ImClass ImClass;
struct ImClass
{
	GtkIMContextClass parent;
};

static GType imtype;

static void
setpreedit(Im *im, const char *s, int n)
{
	int was;

	if(n < 0 || n > Ipcfieldmax)
		n = 0;
	if(n == im->prelen && memcmp(im->pre, s, n) == 0)
		return;
	was = im->prelen;
	if(n > 0)
		memcpy(im->pre, s, n);
	im->pre[n] = '\0';
	im->prelen = n;
	if(was == 0 && n > 0)
		g_signal_emit_by_name(im, "preedit-start");
	g_signal_emit_by_name(im, "preedit-changed");
	if(was > 0 && n == 0)
		g_signal_emit_by_name(im, "preedit-end");
}

static void
srvclose(Im *im)
{
	if(im->fd >= 0)
		close(im->fd);
	im->fd = -1;
	im->ext = 0;
	im->effective = 1;
	im->caretsent = 0;
	setpreedit(im, "", 0);
}

static int
readresp(Im *im, int want, int update, char *commit, int ncommit,
	Ipcresp *resp)
{
	char pre[Ipcfieldmax+1];

	if(ipcreadresp(im->fd, want, commit, ncommit, pre, sizeof pre,
	   resp) < 0)
		return -1;
	if(update)
		setpreedit(im, pre, resp->npreedit);
	return 0;
}

static void
dropwindow(Im *im)
{
	if(im->win != NULL)
		g_object_unref(im->win);
	im->win = NULL;
	im->cursorvalid = 0;
}

static int
caretget(Im *im, int *valid, int32_t *x, int32_t *y, int32_t *h)
{
	gint rx, ry, scale;
	int64_t sx, sy, sh;

	*valid = 0;
	*x = *y = *h = 0;
	if(im->win != NULL && gdk_window_is_destroyed(im->win))
		dropwindow(im);
	if(!im->cursorvalid || im->win == NULL){
		im->cursorvalid = 0;
		return 0;
	}
#ifdef GDK_WINDOWING_X11
	if(!GDK_IS_X11_WINDOW(im->win)){
		im->cursorvalid = 0;
		return 0;
	}
#else
	im->cursorvalid = 0;
	return 0;
#endif
	if(im->cursor.height < 0){
		im->cursorvalid = 0;
		return 0;
	}
	scale = gdk_window_get_scale_factor(im->win);
	if(scale <= 0){
		im->cursorvalid = 0;
		return 0;
	}
	/* GDK translates the client-relative point before device scaling. */
	gdk_window_get_root_coords(im->win, 0, 0, &rx, &ry);
	sx = ((int64_t)rx + im->cursor.x) * scale;
	sy = ((int64_t)ry + im->cursor.y) * scale;
	sh = (int64_t)im->cursor.height * scale;
	if(sx < INT32_MIN || sx > INT32_MAX ||
	   sy < INT32_MIN || sy > INT32_MAX || sh > INT32_MAX){
		im->cursorvalid = 0;
		return 0;
	}
	*valid = 1;
	*x = sx;
	*y = sy;
	*h = sh;
	return 0;
}

static int
sendcaret(Im *im)
{
	unsigned char buf[Ipccaretsz];
	int valid;
	int32_t x, y, h;

	if(im->fd < 0 || !im->ext)
		return 0;
	caretget(im, &valid, &x, &y, &h);
	if(im->caretsent && valid == im->sentvalid &&
	   (!valid || (x == im->sentx && y == im->senty && h == im->senth)))
		return 0;
	if(ipcpackcaret(buf, valid, x, y, h) < 0 ||
	   ipcsend(im->fd, buf, sizeof buf) < 0)
		return -1;
	im->caretsent = 1;
	im->sentvalid = valid;
	im->sentx = x;
	im->senty = y;
	im->senth = h;
	return 0;
}

static int
srvconnect(Im *im)
{
	unsigned char buf[Ipcreqsz];
	char commit[Ipcfieldmax+1];
	Ipcresp resp;

	if(im->fd >= 0)
		return 0;
	im->fd = ipcconnect();
	if(im->fd < 0)
		return -1;
	/* Marker zero is an old daemon's harmless key-zero response. */
	ipcpackcap(buf, im->usepreedit);
	if(ipcsend(im->fd, buf, sizeof buf) < 0 ||
	   readresp(im, im->usepreedit, im->usepreedit, commit,
	   sizeof commit, &resp) < 0){
		srvclose(im);
		return -1;
	}
	im->ext = resp.eaten != 0;
	im->effective = im->ext ? im->usepreedit : 1;
	if(!im->effective)
		setpreedit(im, "", 0);
	if(im->ext && sendcaret(im) < 0){
		srvclose(im);
		return -1;
	}
	return 0;
}

static uint32_t
kget(uint32_t gdk)
{
	uint32_t u;

	u = gdk_keyval_to_unicode(gdk);
	if((gdk & 0xff000000) == 0x01000000 && u != 0)
		return u;
	if(gdk >= 0xff00 && gdk <= 0xffff)
		return Kspec + (gdk - 0xff00);
	return u;
}

static uint32_t
mget(uint32_t state)
{
	uint32_t m;

	m = 0;
	if(state & GDK_SHIFT_MASK)
		m |= Mshift;
	if(state & GDK_CONTROL_MASK)
		m |= Mctrl;
	if(state & GDK_MOD1_MASK)
		m |= Malt;
	if(state & GDK_SUPER_MASK)
		m |= Msuper;
	return m;
}

static void
sendreset(Im *im)
{
	unsigned char buf[Ipcreqsz];
	char commit[Ipcfieldmax+1];
	Ipcresp resp;

	if(im->fd < 0){
		setpreedit(im, "", 0);
		return;
	}
	ipcpackreset(buf, im->effective);
	if(ipcsend(im->fd, buf, sizeof buf) < 0 ||
	   readresp(im, im->effective, 0, commit,
	   sizeof commit, &resp) < 0){
		srvclose(im);
		return;
	}
	setpreedit(im, "", 0);
}

static gboolean
plaincommit(GtkIMContext *ctx, uint32_t key, uint32_t mod)
{
	char u[8];
	int n;

	if(mod & (Mctrl|Malt|Msuper))
		return FALSE;
	if(key < 0x20 || key >= Kspec)
		return FALSE;
	n = g_unichar_to_utf8(key, u);
	u[n] = '\0';
	g_signal_emit_by_name(ctx, "commit", u);
	return TRUE;
}

static gboolean
kpress(GtkIMContext *ctx, GdkEventKey *ev)
{
	Im *im;
	unsigned char buf[Ipcreqsz];
	char commit[Ipcfieldmax+1];
	uint32_t key, mod;
	Ipcresp resp;

	im = (Im*)ctx;
	if(ev->type != GDK_KEY_PRESS)
		return FALSE;
	key = kget(ev->keyval);
	if(key == 0)
		return FALSE;
	mod = mget(ev->state);
	if(im->private)
		return plaincommit(ctx, key, mod);
	if(srvconnect(im) < 0)
		return plaincommit(ctx, key, mod);
	/* A retained GDK window may have moved since the last cursor report. */
	if(sendcaret(im) < 0){
		srvclose(im);
		return plaincommit(ctx, key, mod);
	}
	ipcpackreq(buf, im->effective, mod, key);
	if(ipcsend(im->fd, buf, sizeof buf) < 0 ||
	   readresp(im, im->effective, im->effective, commit,
	   sizeof commit, &resp) < 0){
		srvclose(im);
		return plaincommit(ctx, key, mod);
	}
	if(commit[0] != '\0')
		g_signal_emit_by_name(ctx, "commit", commit);
	if(resp.eaten)
		return TRUE;
	return plaincommit(ctx, key, mod);
}

static void
getpreedit(GtkIMContext *ctx, gchar **str, PangoAttrList **attrs,
	gint *cursor_pos)
{
	Im *im;
	PangoAttribute *u;

	im = (Im*)ctx;
	if(str)
		*str = g_strdup(im->pre);
	if(attrs){
		*attrs = pango_attr_list_new();
		if(im->prelen > 0){
			u = pango_attr_underline_new(PANGO_UNDERLINE_SINGLE);
			u->start_index = 0;
			u->end_index = im->prelen;
			pango_attr_list_insert(*attrs, u);
		}
	}
	if(cursor_pos)
		*cursor_pos = g_utf8_strlen(im->pre, -1);
}

static void
reset(GtkIMContext *ctx)
{
	sendreset((Im*)ctx);
}

static void
focusout(GtkIMContext *ctx)
{
	Im *im;

	im = (Im*)ctx;
	sendreset(im);
	/* Closing the context connection releases engine ownership. */
	srvclose(im);
}

static void
setusepreedit(GtkIMContext *ctx, gboolean use)
{
	Im *im;
	unsigned char buf[Ipcreqsz];
	char commit[Ipcfieldmax+1];
	Ipcresp resp;

	im = (Im*)ctx;
	use = use != FALSE;
	if(im->usepreedit == use)
		return;
	im->usepreedit = use;
	if(im->fd < 0 || !im->ext){
		im->effective = im->ext ? use : 1;
		return;
	}
	ipcpackcap(buf, use);
	if(ipcsend(im->fd, buf, sizeof buf) < 0 ||
	   readresp(im, use, use, commit, sizeof commit, &resp) < 0 ||
	   !resp.eaten){
		srvclose(im);
		return;
	}
	im->effective = use;
	if(!use)
		setpreedit(im, "", 0);
}

static void
setclientwindow(GtkIMContext *ctx, GdkWindow *win)
{
	Im *im;

	im = (Im*)ctx;
	if(win != NULL && gdk_window_is_destroyed(win))
		win = NULL;
	if(im->win == win)
		return;
	if(win != NULL)
		g_object_ref(win);
	dropwindow(im);
	im->win = win;
	if(sendcaret(im) < 0)
		srvclose(im);
}

static void
setcursorlocation(GtkIMContext *ctx, GdkRectangle *area)
{
	Im *im;

	im = (Im*)ctx;
	if(im->win != NULL && gdk_window_is_destroyed(im->win))
		dropwindow(im);
	if(area == NULL || im->win == NULL)
		im->cursorvalid = 0;
	else{
		im->cursor = *area;
		im->cursorvalid = 1;
	}
	if(sendcaret(im) < 0)
		srvclose(im);
}

static int
isprivate(GtkInputPurpose purpose)
{
	return purpose == GTK_INPUT_PURPOSE_PASSWORD ||
		purpose == GTK_INPUT_PURPOSE_PIN;
}

static void
purposechanged(GObject *obj, GParamSpec *pspec, gpointer data)
{
	Im *im;
	GtkInputPurpose purpose;
	int private;

	(void)pspec;
	(void)data;
	im = (Im*)obj;
	g_object_get(obj, "input-purpose", &purpose, NULL);
	private = isprivate(purpose);
	if(private == im->private)
		return;
	im->private = private;
	if(private)
		sendreset(im);
}

static void
finalize(GObject *obj)
{
	Im *im;

	im = (Im*)obj;
	srvclose(im);
	dropwindow(im);
	G_OBJECT_CLASS(g_type_class_peek_parent(G_OBJECT_GET_CLASS(obj)))->finalize(obj);
}

static void
init(Im *im)
{
	GtkInputPurpose purpose;

	im->fd = -1;
	im->usepreedit = 1;
	im->effective = 1;
	im->pre[0] = '\0';
	g_object_get(im, "input-purpose", &purpose, NULL);
	im->private = isprivate(purpose);
	g_signal_connect(im, "notify::input-purpose",
		G_CALLBACK(purposechanged), NULL);
}

static void
classinit(ImClass *klass)
{
	GtkIMContextClass *ic;
	GObjectClass *oc;

	ic = GTK_IM_CONTEXT_CLASS(klass);
	oc = G_OBJECT_CLASS(klass);
	ic->filter_keypress = kpress;
	ic->get_preedit_string = getpreedit;
	ic->reset = reset;
	ic->focus_out = focusout;
	ic->set_use_preedit = setusepreedit;
	ic->set_client_window = setclientwindow;
	ic->set_cursor_location = setcursorlocation;
	oc->finalize = finalize;
}

static const GtkIMContextInfo info = {
	"strans",
	"strans",
	"strans",
	"",
	"*",
};

static const GtkIMContextInfo *infolist[] = { &info };

G_MODULE_EXPORT void
im_module_init(GTypeModule *mod)
{
	static const GTypeInfo ti = {
		sizeof(ImClass),
		NULL, NULL,
		(GClassInitFunc)classinit,
		NULL, NULL,
		sizeof(Im),
		0,
		(GInstanceInitFunc)init,
	};
	imtype = g_type_module_register_type(mod, GTK_TYPE_IM_CONTEXT, "strans-gtk", &ti, 0);
}

G_MODULE_EXPORT void
im_module_exit(void)
{
}

G_MODULE_EXPORT void
im_module_list(const GtkIMContextInfo ***contexts, int *n)
{
	*contexts = infolist;
	*n = 1;
}

G_MODULE_EXPORT GtkIMContext*
im_module_create(const char *id)
{
	if(strcmp(id, "strans") == 0)
		return g_object_new(imtype, NULL);
	return NULL;
}