/*
 * gui.c - GUI for eeshow
 *
 * Written 2016 by Werner Almesberger
 * Copyright 2016 by Werner Almesberger
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 */

/*
 * Resources:
 *
 * http://zetcode.com/gfx/cairo/cairobackends/
 * https://developer.gnome.org/gtk3/stable/gtk-migrating-2-to-3.html
 */

#define	_GNU_SOURCE	/* for asprintf */
#include <stddef.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#include <cairo/cairo.h>
#include <gtk/gtk.h>

#include "util.h"
#include "style.h"
#include "cro.h"
#include "gfx.h"
#include "git-hist.h"
#include "sch.h"
#include "delta.h"
#include "diff.h"
#include "gui-aoi.h"
#include "gui-style.h"
#include "gui-over.h"
#include "gui.h"


struct gui_ctx;

struct gui_sheet {
	const struct sheet *sch;
	struct cro_ctx *gfx_ctx;

	int w, h;		/* in eeschema coordinates */
	int xmin, ymin;

	bool rendered;		/* 0 if still have to render it */

	struct aoi *aois;	/* areas of interest; in schematics coord  */

	struct gui_sheet *next;
};

struct gui_hist {
	struct gui_ctx *ctx;		/* back link */
	struct hist *vcs_hist;		/* NULL if not from repo */
	struct overlay *over;		/* current overlay */
	struct gui_sheet *sheets;	/* NULL if failed */
	unsigned age;			/* 0-based; uncommitted or HEAD = 0 */

	/* caching support */
	void **oids;			/* file object IDs */
	struct lib lib;			/* combined library */

	struct gui_hist *next;
};

struct gui_ctx {
	GtkWidget *da;

	int curr_x;		/* last on-screen mouse position */
	int curr_y;

	unsigned zoom;		/* scale by 1.0 / (1 << zoom) */
	int x, y;		/* center, in eeschema coordinates */

	bool panning;
	int pan_x, pan_y;

	struct gui_hist *hist;	/* revision history; NULL if none */
	struct hist *vcs_hist;	/* underlying VCS data; NULL if none */

	bool showing_history;
	enum selecting {
		sel_only,	/* select the only revision we show */
		sel_new,	/* select the new revision */
		sel_old,	/* select the old revision */
	} selecting;

	struct overlay *sheet_overlays;
	struct overlay *hist_overlays;
	struct aoi *aois;	/* areas of interest; in canvas coord  */

	struct gui_sheet delta_a;
	struct gui_sheet delta_b;
	struct gui_sheet delta_ab;

	struct gui_sheet *curr_sheet;
				/* current sheet, always on new_hist */
	struct gui_hist *new_hist;
	struct gui_hist *old_hist;	/* NULL if not comparing */
};


/* ----- Helper functions -------------------------------------------------- */


static void redraw(const struct gui_ctx *ctx)
{
	gtk_widget_queue_draw(ctx->da);
}


static struct gui_sheet *find_corresponding_sheet(struct gui_sheet *pick_from,
     struct gui_sheet *ref_in, const struct gui_sheet *ref)
{
	struct gui_sheet *sheet, *plan_b;
	const char *title = ref->sch->title;

	/* plan A: try to find sheet with same name */

	if (title)
		for (sheet = pick_from; sheet; sheet = sheet->next)
			if (sheet->sch->title &&
			    !strcmp(title, sheet->sch->title))
				return sheet;

	/* plan B: use sheet in same position in sheet sequence */

	plan_b = ref_in;
	for (sheet = pick_from; sheet; sheet = sheet->next) {
		if (plan_b == ref)
			return sheet;
		plan_b = plan_b->next;
	}

	/* plan C: just go to the top */
	return pick_from;
}


/* ----- Rendering --------------------------------------------------------- */


#define	VCS_OVERLAYS_X		5
#define	VCS_OVERLAYS_Y		5

#define	SHEET_OVERLAYS_X	-10
#define	SHEET_OVERLAYS_Y	10


static void hack(const struct gui_ctx *ctx, cairo_t *cr)
{
	const struct gui_sheet *new = ctx->curr_sheet;
	const struct gui_sheet *old = find_corresponding_sheet(
	    ctx->old_hist->sheets, ctx->new_hist->sheets, ctx->curr_sheet);

	diff_to_canvas(cr, ctx->x, ctx->y, 1.0 / (1 << ctx->zoom),
	    old->gfx_ctx, new->gfx_ctx);
}


static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr,
    gpointer user_data)
{
	const struct gui_ctx *ctx = user_data;
	const struct gui_sheet *sheet = ctx->curr_sheet;
	GtkAllocation alloc;
	float f = 1.0 / (1 << ctx->zoom);
	int x, y;

	gtk_widget_get_allocation(ctx->da, &alloc);
	x = -(sheet->xmin + ctx->x) * f + alloc.width / 2;
	y = -(sheet->ymin + ctx->y) * f + alloc.height / 2;

	cro_canvas_prepare(cr);
	if (!ctx->old_hist) {
		cro_canvas_draw(sheet->gfx_ctx, cr, x, y, f);
	} else {
#if 0
		/* @@@ fix geometry later */
		cro_canvas_draw(ctx->delta_ab.gfx_ctx, cr, x, y, f);
		cro_canvas_draw(ctx->delta_a.gfx_ctx, cr, x, y, f);
		cro_canvas_draw(ctx->delta_b.gfx_ctx, cr, x, y, f);
#endif
		hack(ctx, cr);
	}

	overlay_draw_all(ctx->sheet_overlays, cr,
	    SHEET_OVERLAYS_X, SHEET_OVERLAYS_Y);
	overlay_draw_all(ctx->hist_overlays, cr,
	    VCS_OVERLAYS_X, VCS_OVERLAYS_Y);

	return FALSE;
}


static void render_sheet(struct gui_sheet *sheet)
{
	char *argv[] = { "gui", NULL };

	gfx_init(&cro_canvas_ops, 1, argv);
	sch_render(sheet->sch);
	cro_canvas_end(gfx_ctx,
	    &sheet->w, &sheet->h, &sheet->xmin, &sheet->ymin);
	sheet->gfx_ctx = gfx_ctx;
	sheet->rendered = 1;
	// gfx_end();
}


/* @@@ not nice to have this so far out */
static void mark_aois(struct gui_ctx *ctx, struct gui_sheet *sheet);


static void render_delta(struct gui_ctx *ctx)
{
#if 0
	/* @@@ needs updating for curr/last vs. new/old */
	struct sheet *sch_a, *sch_b, *sch_ab;
	const struct gui_sheet *a = ctx->curr_sheet;
	const struct gui_sheet *b = find_corresponding_sheet(
	    ctx->last_hist->sheets, ctx->curr_hist->sheets, ctx->curr_sheet);

	sch_a = alloc_type(struct sheet);
	sch_b = alloc_type(struct sheet);
	sch_ab = alloc_type(struct sheet);

	delta(a->sch, b->sch, sch_a, sch_b, sch_ab);
	ctx->delta_a.sch = sch_a,
	ctx->delta_b.sch = sch_b,
	ctx->delta_ab.sch = sch_ab,

	render_sheet(&ctx->delta_a);
	render_sheet(&ctx->delta_b);
	render_sheet(&ctx->delta_ab);

	cro_color_override(ctx->delta_ab.gfx_ctx, COLOR_LIGHT_GREY);
	cro_color_override(ctx->delta_a.gfx_ctx, COLOR_RED);
	cro_color_override(ctx->delta_b.gfx_ctx, COLOR_GREEN2);

	// @@@ clean up when leaving sheet
#endif
	struct gui_sheet *b = find_corresponding_sheet(
	    ctx->old_hist->sheets, ctx->new_hist->sheets, ctx->curr_sheet);

	if (!b->rendered) {
		render_sheet(b);
		mark_aois(ctx, b);
	}
}


/* ----- Tools ------------------------------------------------------------- */


static void canvas_coord(const struct gui_ctx *ctx,
    int ex, int ey, int *x, int *y)
{
	GtkAllocation alloc;
	int sx, sy;

	gtk_widget_get_allocation(ctx->da, &alloc);
	sx = ex - alloc.width / 2;
	sy = ey - alloc.height / 2;
	*x = (sx << ctx->zoom) + ctx->x;
	*y = (sy << ctx->zoom) + ctx->y;
}


/* ----- Panning ----------------------------------------------------------- */


static void pan_begin(struct gui_ctx *ctx, int x, int y)
{
	if (ctx->panning)
		return;
	ctx->panning = 1;
	ctx->pan_x = x;
	ctx->pan_y = y;
}


static void pan_update(struct gui_ctx *ctx, int x, int y)
{
	if (!ctx->panning)
		return;

	ctx->x -= (x - ctx->pan_x) << ctx->zoom;
	ctx->y -= (y - ctx->pan_y) << ctx->zoom;
	ctx->pan_x = x;
	ctx->pan_y = y;

	redraw(ctx);
}


static void pan_end(struct gui_ctx *ctx, int x, int y)
{
	pan_update(ctx, x, y);
	ctx->panning = 0;
}


/* ----- Zoom -------------------------------------------------------------- */



static void zoom_in(struct gui_ctx *ctx, int x, int y)
{
	if (ctx->zoom == 0)
		return;
	ctx->zoom--;
	ctx->x = (ctx->x + x) / 2;
	ctx->y = (ctx->y + y) / 2;
	redraw(ctx);
}


static void zoom_out(struct gui_ctx *ctx, int x, int y)
{
	if (ctx->curr_sheet->w >> ctx->zoom <= 16)
		return;
	ctx->zoom++;
	ctx->x = 2 * ctx->x - x;
	ctx->y = 2 * ctx->y - y;
	redraw(ctx);
}


static void curr_sheet_size(struct gui_ctx *ctx, int *w, int *h)
{
	const struct gui_sheet *sheet = ctx->curr_sheet;
	int ax1, ay1, bx1, by1;

	if (!ctx->old_hist) {
		*w = sheet->w;
		*h = sheet->h;
	} else {
		const struct gui_sheet *old =
		    find_corresponding_sheet(ctx->old_hist->sheets,
		    ctx->new_hist->sheets, sheet);

		/*
		 * We're only interested in differences here, so no need for
		 * the usual "-1" in x1 = x0 + w - 1
		 */
		ax1 = sheet->xmin + sheet->w;
		ay1 = sheet->ymin + sheet->h;
		bx1 = old->xmin + old->w;
		by1 = old->ymin + old->h;
		*w = (ax1 > bx1 ? ax1 : bx1) -
		    (sheet->xmin < old->xmin ? sheet->xmin : old->xmin);
		*h = (ay1 > by1 ? ay1 : by1) -
		    (sheet->ymin < old->ymin ? sheet->ymin : old->ymin);
	}
}


static void zoom_to_extents(struct gui_ctx *ctx)
{
	GtkAllocation alloc;
	int w, h;

	curr_sheet_size(ctx, &w, &h);
	ctx->x = w / 2;
	ctx->y = h / 2;

	gtk_widget_get_allocation(ctx->da, &alloc);
	ctx->zoom = 0;
	while (w >> ctx->zoom > alloc.width || h >> ctx->zoom > alloc.height)
		ctx->zoom++;

	redraw(ctx);
}


/* ----- Need this for jumping around -------------------------------------- */


static void go_to_sheet(struct gui_ctx *ctx, struct gui_sheet *sheet);
static bool go_up_sheet(struct gui_ctx *ctx);


/* ----- Revision history -------------------------------------------------- */


static void do_revision_overlays(struct gui_ctx *ctx);


static void hide_history(struct gui_ctx *ctx)
{
	ctx->showing_history = 0;
	do_revision_overlays(ctx);
	redraw(ctx);
}


#define	RGBA(r, g, b, a)	((struct color) { (r), (g), (b), (a) })
#define	COLOR(color)		RGBA(color)


static void set_history_style(struct gui_hist *h, bool current)
{
	struct gui_ctx *ctx = h->ctx;
	struct overlay_style style = overlay_style_dense;
	const struct gui_hist *new = ctx->new_hist;
	const struct gui_hist *old = ctx->old_hist;

	/* this is in addition to showing detailed content */
	if (current)
		style.width++;

	switch (ctx->selecting) {
	case sel_only:
		style.frame = COLOR(FRAME_SEL_ONLY);
		break;
	case sel_old:
		style.frame = COLOR(FRAME_SEL_OLD);
		break;
	case sel_new:
		style.frame = COLOR(FRAME_SEL_NEW);
		break;
	default:
		abort();
	}

	if (ctx->new_hist == h || ctx->old_hist == h) {
		style.width++;
		style.font = BOLD_FONT;
	}
	if (ctx->old_hist) {
		if (h == new)
			style.bg = COLOR(BG_NEW);
		if (h == old)
			style.bg = COLOR(BG_OLD);
	}
	overlay_style(h->over, &style);
}


static bool hover_history(void *user, bool on)
{
	struct gui_hist *h = user;
	struct gui_ctx *ctx = h->ctx;
	char *s;

	if (on) {
		s = vcs_git_long_for_pango(h->vcs_hist);
		overlay_text_raw(h->over, s);
		free(s);
	} else {
		overlay_text(h->over, "<small>%s</small>",
		    vcs_git_summary(h->vcs_hist));
	}
	set_history_style(h, on);
	redraw(ctx);
	return 1;
}


static void click_history(void *user)
{
	struct gui_hist *h = user;
	struct gui_ctx *ctx = h->ctx;
	struct gui_sheet *sheet;

	hide_history(ctx);

	if (!h->sheets)
		return;

	sheet = find_corresponding_sheet(h->sheets,
	    ctx->new_hist->sheets, ctx->curr_sheet);

	switch (ctx->selecting) {
	case sel_only:
		ctx->old_hist = ctx->new_hist;
		ctx->new_hist = h;
		break;
	case sel_new:
		ctx->new_hist = h;
		break;
	case sel_old:
		ctx->old_hist = h;
		break;
	default:
		abort();
	}

	if (ctx->new_hist->age > ctx->old_hist->age) {
		swap(ctx->new_hist, ctx->old_hist);
		if (ctx->selecting == sel_old)
			go_to_sheet(ctx, sheet);
		else
			render_delta(ctx);
	} else {
		if (ctx->selecting != sel_old)
			go_to_sheet(ctx, sheet);
		else
			render_delta(ctx);
	}

	if (ctx->old_hist == ctx->new_hist)
		ctx->old_hist = NULL;

	do_revision_overlays(ctx);
	redraw(ctx);
}


static void show_history(struct gui_ctx *ctx, enum selecting sel)
{
	struct gui_hist *h = ctx->hist;

	ctx->showing_history = 1;
	ctx->selecting = sel;
	overlay_remove_all(&ctx->hist_overlays);
	for (h = ctx->hist; h; h = h->next) {
		h->over = overlay_add(&ctx->hist_overlays, &ctx->aois,
		    hover_history, click_history, h);
		hover_history(h, 0);
		set_history_style(h, 0);
	}
	redraw(ctx);
}


static void show_history_cb(void *user)
{
	struct gui_hist *h = user;
	struct gui_ctx *ctx = h->ctx;
	enum selecting sel = sel_only;

	if (ctx->old_hist)
		sel = h == ctx->new_hist ? sel_new : sel_old;
	show_history(ctx, sel);
}


/* ----- Navigate sheets --------------------------------------------------- */


/* @@@ find a better place for this forward declaration */
static void mark_aois(struct gui_ctx *ctx, struct gui_sheet *sheet);


static void close_subsheet(void *user)
{
	struct gui_ctx *ctx = user;

	go_up_sheet(ctx);
}


static bool show_history_details(void *user, bool on)
{
	struct gui_hist *h = user;
	struct gui_ctx *ctx = h->ctx;
	char *s;

	if (on) {
		s = vcs_git_long_for_pango(h->vcs_hist);
		overlay_text_raw(h->over, s);
		free(s);
	} else {
		overlay_text(h->over, "%.40s", vcs_git_summary(h->vcs_hist));
	}
	redraw(ctx);
	return 1;
}


static void revision_overlays_diff(struct gui_ctx *ctx)
{
	struct gui_hist *new = ctx->new_hist;
	struct gui_hist *old = ctx->old_hist;

	new->over = overlay_add(&ctx->hist_overlays, &ctx->aois,
	    show_history_details, show_history_cb, new);
	overlay_style(new->over, &overlay_style_diff_new);
	show_history_details(new, 0);

	old->over = overlay_add(&ctx->hist_overlays, &ctx->aois,
	    show_history_details, show_history_cb, old);
	overlay_style(old->over, &overlay_style_diff_old);
	show_history_details(old, 0);
}


static void do_revision_overlays(struct gui_ctx *ctx)
{
	overlay_remove_all(&ctx->hist_overlays);

	if (ctx->old_hist) {
		revision_overlays_diff(ctx);
	} else {
		ctx->new_hist->over = overlay_add(&ctx->hist_overlays,
		    &ctx->aois, show_history_details, show_history_cb,
		    ctx->new_hist);
		overlay_style(ctx->new_hist->over, &overlay_style_default);
		show_history_details(ctx->new_hist, 0);
	}
}


static struct gui_sheet *find_parent_sheet(struct gui_sheet *sheets,
    const struct gui_sheet *ref)
{
	struct gui_sheet *parent;
	const struct sch_obj *obj;

	for (parent = sheets; parent; parent = parent->next)
		for (obj = parent->sch->objs; obj; obj = obj->next)
			if (obj->type == sch_obj_sheet &&
			    obj->u.sheet.sheet == ref->sch)
				return parent;
	return NULL;
}


static void sheet_selector_recurse(struct gui_ctx *ctx,
    const struct gui_sheet *sheet)
{
	const struct gui_sheet *parent;
	const char *title;
	struct overlay *over;

	parent = find_parent_sheet(ctx->new_hist->sheets, sheet);
	if (parent)
		sheet_selector_recurse(ctx, parent);
	title = sheet->sch->title;
	if (!title)
		title = "(unnamed)";
	/*
	 * @@@ dirty hack: instead of jumping to the selected sheet (which
	 * would require a little more work), we merely go "up". In a flat
	 * hierarchy with just one level of sub-sheets, that does pretty
	 * much what one would expect from proper jumping.
	 */
	over = overlay_add(&ctx->sheet_overlays, &ctx->aois,
	    NULL, close_subsheet, ctx);
	overlay_text(over, "<b>%s</b>", title);
}


static void do_sheet_overlays(struct gui_ctx *ctx)
{
	overlay_remove_all(&ctx->sheet_overlays);
	sheet_selector_recurse(ctx, ctx->curr_sheet);
}


static void go_to_sheet(struct gui_ctx *ctx, struct gui_sheet *sheet)
{
	if (!sheet->rendered) {
		render_sheet(sheet);
		mark_aois(ctx, sheet);
	}
	ctx->curr_sheet = sheet;
	if (ctx->old_hist)
		render_delta(ctx);
	if (ctx->vcs_hist)
		do_revision_overlays(ctx);
	do_sheet_overlays(ctx);
	zoom_to_extents(ctx);
}


static bool go_up_sheet(struct gui_ctx *ctx)
{
	struct gui_sheet *parent;

	parent = find_parent_sheet(ctx->new_hist->sheets, ctx->curr_sheet);
	if (!parent)
		return 0;
	go_to_sheet(ctx, parent);
	return 1;
}


static bool go_prev_sheet(struct gui_ctx *ctx)
{
	struct gui_sheet *sheet;

	for (sheet = ctx->new_hist->sheets; sheet; sheet = sheet->next)
		if (sheet->next && sheet->next == ctx->curr_sheet) {
			go_to_sheet(ctx, sheet);
			return 1;
		}
	return 0;
}


static bool go_next_sheet(struct gui_ctx *ctx)
{
	if (!ctx->curr_sheet->next)
		return 0;
	go_to_sheet(ctx, ctx->curr_sheet->next);
	return 1;
}


/* ----- Event handlers ---------------------------------------------------- */


static gboolean motion_notify_event(GtkWidget *widget, GdkEventMotion *event,
    gpointer data)
{
	struct gui_ctx *ctx = data;
	const struct gui_sheet *curr_sheet = ctx->curr_sheet;
	int x, y;

	ctx->curr_x = event->x;
	ctx->curr_y = event->y;

	canvas_coord(ctx, event->x, event->y, &x, &y);

	aoi_hover(ctx->aois, event->x, event->y) ||
	    aoi_hover(curr_sheet->aois,
	    x + curr_sheet->xmin, y + curr_sheet->ymin);
	pan_update(ctx, event->x, event->y);

	return TRUE;
}


static gboolean button_press_event(GtkWidget *widget, GdkEventButton *event,
    gpointer data)
{
	struct gui_ctx *ctx = data;
	const struct gui_sheet *curr_sheet = ctx->curr_sheet;
	int x, y;

	canvas_coord(ctx, event->x, event->y, &x, &y);

	switch (event->button) {
	case 1:
		if (aoi_click(ctx->aois, event->x, event->y))
			break;
		if (aoi_click(curr_sheet->aois,
		    x + curr_sheet->xmin, y + curr_sheet->ymin))
			break;
		if (ctx->showing_history)
			hide_history(ctx);
		break;
	case 2:
		pan_begin(ctx, event->x, event->y);
		break;
	case 3:
		break;
	}
	return TRUE;
}


static gboolean button_release_event(GtkWidget *widget, GdkEventButton *event,
    gpointer data)
{
	struct gui_ctx *ctx = data;
	int x, y;

	canvas_coord(ctx, event->x, event->y, &x, &y);

	switch (event->button) {
	case 1:
		break;
	case 2:
		pan_end(ctx, event->x, event->y);
		break;
	case 3:
		break;
	}
	return TRUE;
}


static gboolean key_press_event(GtkWidget *widget, GdkEventKey *event,
    gpointer data)
{
	struct gui_ctx *ctx = data;
	struct gui_sheet *sheet = ctx->curr_sheet;
	int x, y;

	canvas_coord(ctx, ctx->curr_x, ctx->curr_y, &x, &y);

	switch (event->keyval) {
	case '+':
	case '=':
		zoom_in(ctx, x, y);
		break;
	case '-':
		zoom_out(ctx, x, y);
		break;
	case '*':
		zoom_to_extents(ctx);
		break;
	case GDK_KEY_Home:
		if (sheet != ctx->new_hist->sheets)
			go_to_sheet(ctx, ctx->new_hist->sheets);
		break;
	case GDK_KEY_BackSpace:
	case GDK_KEY_Delete:
		go_up_sheet(ctx);
		break;
	case GDK_KEY_Page_Up:
	case GDK_KEY_KP_Page_Up:
		go_prev_sheet(ctx);
		break;
	case GDK_KEY_Page_Down:
	case GDK_KEY_KP_Page_Down:
		go_next_sheet(ctx);
		break;
	case GDK_KEY_Up:
	case GDK_KEY_KP_Up:
		show_history(ctx, sel_new);
		break;
	case GDK_KEY_Down:
	case GDK_KEY_KP_Down:
		show_history(ctx, sel_old);
		break;
	case GDK_KEY_q:
		gtk_main_quit();
	}
	return TRUE;
}


static gboolean scroll_event(GtkWidget *widget, GdkEventScroll *event,
    gpointer data)
{
	struct gui_ctx *ctx = data;
	int x, y;

	canvas_coord(ctx, event->x, event->y, &x, &y);
	switch (event->direction) {
	case GDK_SCROLL_UP:
		zoom_in(ctx, x, y);
		break;
	case GDK_SCROLL_DOWN:
		zoom_out(ctx, x, y);
		break;
	default:
		/* ignore */;
	}
	return TRUE;
}


static void size_allocate_event(GtkWidget *widget, GdkRectangle *allocation,
    gpointer data)
{
	struct gui_ctx *ctx = data;

	zoom_to_extents(ctx);
}


/* ----- AoI callbacks ----------------------------------------------------- */


struct sheet_aoi_ctx {
	struct gui_ctx *gui_ctx;
	const struct sch_obj *obj;
};


static void select_subsheet(void *user)
{
	const struct sheet_aoi_ctx *aoi_ctx = user;
	struct gui_ctx *ctx = aoi_ctx->gui_ctx;
	const struct sch_obj *obj = aoi_ctx->obj;
	struct gui_sheet *sheet;

	for (sheet = ctx->new_hist->sheets; sheet; sheet = sheet->next)
		if (sheet->sch == obj->u.sheet.sheet) {
			go_to_sheet(ctx, sheet);
			return;
		}
	abort();
}


/* ----- Initialization ---------------------------------------------------- */


static void add_sheet_aoi(struct gui_ctx *ctx, struct gui_sheet *parent,
    const struct sch_obj *obj)
{
	struct sheet_aoi_ctx *aoi_ctx = alloc_type(struct sheet_aoi_ctx);

	aoi_ctx->gui_ctx = ctx;
	aoi_ctx->obj = obj;

	struct aoi aoi = {
		.x	= obj->x,
		.y	= obj->y,
		.w	= obj->u.sheet.w,
		.h	= obj->u.sheet.h,
		.click	= select_subsheet,
		.user	= aoi_ctx,
	};

	aoi_add(&parent->aois, &aoi);
}


static void mark_aois(struct gui_ctx *ctx, struct gui_sheet *sheet)
{
	const struct sch_obj *obj;

	sheet->aois = NULL;
	for (obj = sheet->sch->objs; obj; obj = obj->next)
		switch (obj->type) {
		case sch_obj_sheet:
			add_sheet_aoi(ctx, sheet, obj);
			break;
		default:
			break;
		}
}


static struct gui_sheet *get_sheets(struct gui_ctx *ctx,
    const struct sheet *sheets)
{
	const struct sheet *sheet;
	struct gui_sheet *gui_sheets = NULL;
	struct gui_sheet **next = &gui_sheets;
	struct gui_sheet *new;

	for (sheet = sheets; sheet; sheet = sheet->next) {
		new = alloc_type(struct gui_sheet);
		new->sch = sheet;
		new->rendered = 0;

		*next = new;
		next = &new->next;
	}
	*next = NULL;
	return gui_sheets;
}


/*
 * Library caching:
 *
 * We reuse previous components if all libraries are identical
 *
 * Future optimizations:
 * - don't parse into single list of components, so that we can share
 *   libraries that are the same, even if there are others that have changed.
 * - maybe put components into tree, so that they can be replaced individually
 *   (this would also help to identify sheets that don't need parsing)
 */

static const struct sheet *parse_files(struct gui_hist *hist,
    int n_args, char **args, bool recurse, const struct gui_hist *prev)
{
	char *rev = NULL;
	struct sch_ctx sch_ctx;
	struct file sch_file;
	struct file lib_files[n_args - 1];
	int libs_open, i;
	bool libs_cached = 0;
	bool ok;

	if (hist->vcs_hist)
		rev = vcs_git_get_rev(hist->vcs_hist);

	sch_init(&sch_ctx, recurse);
	ok = file_open_revision(&sch_file, rev, args[n_args - 1], NULL);

	if (rev)
		free(rev);
	if (!ok) {
		sch_free(&sch_ctx);
		return NULL;
	}

	lib_init(&hist->lib);
	for (libs_open = 0; libs_open != n_args - 1; libs_open++)
		if (!file_open(lib_files + libs_open, args[libs_open],
		    &sch_file))
			goto fail;

	if (hist->vcs_hist) {
		hist->oids = alloc_size(sizeof(void *) * libs_open);
		for (i = 0; i != libs_open; i++)
			hist->oids[i] = file_oid(lib_files + i);
		if (prev && prev->vcs_hist) {
			for (i = 0; i != libs_open; i++)
				if (!file_oid_eq(hist->oids[i], prev->oids[i]))
					break;
			if (i == libs_open) {
				hist->lib.comps = prev->lib.comps;
				libs_cached = 1;
			}
		}
	}

	if (!libs_cached)
		for (i = 0; i != libs_open; i++)
			if (!lib_parse_file(&hist->lib, lib_files +i))
				goto fail;

	if (!sch_parse(&sch_ctx, &sch_file, &hist->lib))
		goto fail;

	for (i = 0; i != libs_open; i++)
		file_close(lib_files + i);
	file_close(&sch_file);

	/*
	 * @@@ we have a major memory leak for the component library.
	 * We should record parsed schematics and libraries separately, so
	 * that we can clean them up, without having to rely on the history,
	 * with - when sharing unchanged item - possibly many duplicate
	 * pointers.
	 */
	return sch_ctx.sheets;

fail:
	while (libs_open--)
		file_close(lib_files + libs_open);
	sch_free(&sch_ctx);
	lib_free(&hist->lib);
	file_close(&sch_file);
	return NULL;
}


struct add_hist_ctx {
	struct gui_ctx *ctx;
	int n_args;
	char **args;
	bool recurse;
	unsigned limit;
};


static void add_hist(void *user, struct hist *h)
{
	struct add_hist_ctx *ahc = user;
	struct gui_ctx *ctx = ahc->ctx;
	struct gui_hist **anchor, *hist, *prev;
	const struct sheet *sch;
	unsigned age = 0;

	if (!ahc->limit)
		return;
	ahc->limit--;

	prev = NULL;
	for (anchor = &ctx->hist; *anchor; anchor = &(*anchor)->next) {
		prev = *anchor;
		age++;
	}

	hist = alloc_type(struct gui_hist);
	hist->ctx = ctx;
	hist->vcs_hist = h;
	sch = parse_files(hist, ahc->n_args, ahc->args, ahc->recurse, prev);
	hist->sheets = sch ? get_sheets(ctx, sch) : NULL;
	hist->age = age;

	hist->next = NULL;
	*anchor = hist;
}


static void get_revisions(struct gui_ctx *ctx,
    int n_args, char **args, bool recurse, int limit)
{
	const char *sch_name = args[n_args - 1];
	struct add_hist_ctx add_hist_ctx = {
		.ctx		= ctx,
		.n_args		= n_args,
		.args		= args,
		.recurse	= recurse,
		.limit		= limit < 0 ? -limit : limit,
	};

	if (!vcs_git_try(sch_name)) {
		ctx->vcs_hist = NULL;
		add_hist(&add_hist_ctx, NULL);
	} else {
		ctx->vcs_hist = vcs_git_hist(sch_name);
		hist_iterate(ctx->vcs_hist, add_hist, &add_hist_ctx);
	}
}


int gui(unsigned n_args, char **args, bool recurse, int limit)
{
	GtkWidget *window;
	struct gui_ctx ctx = {
		.zoom		= 4,	/* scale by 1 / 16 */
		.panning	= 0,
		.hist		= NULL,
		.vcs_hist	= NULL,
		.showing_history= 0,
		.sheet_overlays	= NULL,
		.hist_overlays	= NULL,
		.aois		= NULL,
		.old_hist	= NULL,
	};

	get_revisions(&ctx, n_args, args, recurse, limit);
	for (ctx.new_hist = ctx.hist; ctx.new_hist && !ctx.new_hist->sheets;
	    ctx.new_hist = ctx.new_hist->next);
	if (!ctx.new_hist) {
		fprintf(stderr, "no valid sheets\n");
		return 1;
	}

	window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

	ctx.da = gtk_drawing_area_new();
	gtk_container_add(GTK_CONTAINER(window), ctx.da);

	g_signal_connect(G_OBJECT(ctx.da), "draw",
	    G_CALLBACK(on_draw_event), &ctx);
	g_signal_connect(G_OBJECT(ctx.da), "motion_notify_event",
	    G_CALLBACK(motion_notify_event), &ctx);
	g_signal_connect(G_OBJECT(ctx.da), "button_press_event",
	    G_CALLBACK(button_press_event), &ctx);
	g_signal_connect(G_OBJECT(ctx.da), "button_release_event",
	    G_CALLBACK(button_release_event), &ctx);
	g_signal_connect(G_OBJECT(ctx.da), "scroll_event",
	    G_CALLBACK(scroll_event), &ctx);
	g_signal_connect(G_OBJECT(ctx.da), "key_press_event",
	    G_CALLBACK(key_press_event), &ctx);
	g_signal_connect(G_OBJECT(ctx.da), "size_allocate",
	    G_CALLBACK(size_allocate_event), &ctx);

	g_signal_connect(window, "destroy",
	    G_CALLBACK(gtk_main_quit), NULL);

	gtk_widget_set_can_focus(ctx.da, TRUE);

	gtk_widget_set_events(ctx.da,
	    GDK_EXPOSE | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK |
	    GDK_KEY_PRESS_MASK |
	    GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
	    GDK_SCROLL_MASK |
	    GDK_POINTER_MOTION_MASK);

//	gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
	gtk_window_set_default_size(GTK_WINDOW(window), 640, 480);
	gtk_window_set_title(GTK_WINDOW(window), "eeshow");

	go_to_sheet(&ctx, ctx.new_hist->sheets);
	gtk_widget_show_all(window);

	/* for performance testing, use -N-depth */
	if (limit >= 0)
		gtk_main();

	return 0;
}