/*
 * layer.h - Separate graphics operations by layers and replay
 *
 * 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.
 */


#include <stdlib.h>
#include <limits.h>
#include <math.h>

#include "util.h"
#include "style.h"
#include "gfx.h"
#include "text.h"
#include "layer.h"


struct layer_obj {
	enum lo_type {
		lo_line,
		lo_rect,
		lo_poly,
		lo_circ,
		lo_arc,
		lo_text,
	} type;

	int x, y;
	int color, fill_color;
	union {
		struct {
			int ex, ey;
		} line;
		struct {
			int ex, ey;
		} rect;
		struct {
			unsigned n;
			int *vx, *vy;
		} poly;
		struct {
			int r;
		} circ;
		struct {
			int r;
			int sa, ea;
		} arc;
		struct {
			char *s;
			unsigned size;
			enum text_align align;
			int rot;
		} text;
	} u;
	struct layer_obj *next;
};


static void bb(struct layer *layer, int x, int y)
{
	if (layer->xmin > x)
		layer->xmin = x;
	if (layer->ymin > y)
		layer->ymin = y;
	if (layer->xmax < x)
		layer->xmax = x;
	if (layer->ymax < y)
		layer->ymax = y;
}


static void bb_rot(struct layer *layer, int x, int y, int rot)
{
	double a = -rot / 180.0 * M_PI;

	// @@@ figure this out later
return;
	bb(layer, cos(a) * x + sin(a) * y, cos(a) * y - sin(a) * x);
}


static struct layer_obj *new_obj(struct layer *lc, enum lo_type type,
    int color, int fill_color, unsigned layer)
{
	struct layer_objs **objs;
	struct layer_objs *new_objs;
	struct layer_obj *new_obj;

	for (objs = &lc->objs; *objs; objs = &(*objs)->next) {
		if ((*objs)->layer == layer)
			goto this_layer;
		if ((*objs)->layer < layer)
			break;
	}

	new_objs = alloc_type(struct layer_objs);
	new_objs->layer = layer;
	new_objs->obj = NULL;
	new_objs->next_obj = &new_objs->obj;
	new_objs->next = *objs;
	*objs = new_objs;

this_layer:
	new_obj = alloc_type(struct layer_obj);
	new_obj->type = type;
	new_obj->color = color;
	new_obj->fill_color = fill_color;
	new_obj->next = NULL;

	*(*objs)->next_obj = new_obj;
	(*objs)->next_obj = &new_obj->next;

	return new_obj;
}


void layer_line(void *ctx, int sx, int sy, int ex, int ey,
    int color, unsigned layer)
{
	struct layer *lc = ctx;
	struct layer_obj *obj = new_obj(ctx, lo_line, color, COLOR_NONE, layer);

	bb(lc, sx, sy);
	bb(lc, ex, ey);

	obj->x = sx;
	obj->y = sy;
	obj->u.line.ex = ex;
	obj->u.line.ey = ey;
}


void layer_rect(void *ctx, int sx, int sy, int ex, int ey,
    int color, int fill_color, unsigned layer)
{
	struct layer *lc = ctx;
	struct layer_obj *obj = new_obj(ctx, lo_rect, color, fill_color, layer);

	bb(lc, sx, sy);
	bb(lc, ex, ey);

	obj->x = sx;
	obj->y = sy;
	obj->u.rect.ex = ex;
	obj->u.rect.ey = ey;
}


void layer_poly(void *ctx, int points, int x[points], int y[points],
    int color, int fill_color, unsigned layer)
{
	struct layer *lc = ctx;
	struct layer_obj *obj = new_obj(ctx, lo_poly, color, fill_color, layer);
	int i;
	unsigned  size;

	for (i = 0; i != points; i++)
		bb(lc, x[i], y[i]);

	obj->u.poly.n = points;
	size = sizeof(int) * points;
	obj->u.poly.vx = alloc_size(size);
	obj->u.poly.vy = alloc_size(size);
	memcpy(obj->u.poly.vx, x, size);
	memcpy(obj->u.poly.vy, y, size);
}


void layer_circ(void *ctx, int x, int y, int r,
    int color, int fill_color, unsigned layer)
{
	struct layer *lc = ctx;
	struct layer_obj *obj = new_obj(ctx, lo_circ, color, fill_color, layer);

	bb(lc, x - r, y - r);
	bb(lc, x + r, y + r);

	obj->x = x;
	obj->y = y;
	obj->u.circ.r = r;
}


void layer_arc(void *ctx, int x, int y, int r, int sa, int ea,
    int color, int fill_color, unsigned layer)
{
	struct layer *lc = ctx;
	struct layer_obj *obj = new_obj(ctx, lo_arc, color, fill_color, layer);

	bb(lc, x - r, y - r);
	bb(lc, x + r, y + r);

	obj->x = x;
	obj->y = y;
	obj->u.arc.r = r;
	obj->u.arc.sa = sa;
	obj->u.arc.ea = ea;
}


void layer_text(void *ctx, int x, int y, const char *s, unsigned size,
    enum text_align align, int rot, unsigned color, unsigned layer)
{
	struct layer *lc = ctx;
	struct layer_obj *obj = new_obj(ctx, lo_text, color, COLOR_NONE, layer);
	unsigned width = lc->ops->text_width(lc->user, s, size);

	bb_rot(lc, x, y - size, rot);
	bb_rot(lc, x + width, y, rot);

	obj->x = x;
	obj->y = y;
	obj->u.text.s = stralloc(s);
	obj->u.text.size = size;
	obj->u.text.align = align;
	obj->u.text.rot = rot;
}


void layer_init(struct layer *layer, const struct gfx_ops *ops, void *user)
{
	layer->ops = ops;
	layer->user = user;
	layer->xmin = layer->ymin = INT_MAX;
	layer->xmax = layer->ymax = INT_MIN;
	layer->objs = NULL;
}


void layer_wipe(struct layer *layer)
{
	layer->objs = NULL;
}


void layer_replay(const struct layer *layer)
{
	const struct gfx_ops *ops = layer->ops;
	void *ctx = layer->user;
	const struct layer_objs *objs;
	const struct layer_obj *obj;

	for (objs = layer->objs; objs; objs = objs->next)
		for (obj = objs->obj; obj; obj = obj->next)
			switch (obj->type) {
			case lo_line:
				ops->line(ctx, obj->x, obj->y,
				    obj->u.line.ex, obj->u.line.ey,
				    obj->color, objs->layer);
				break;
			case lo_rect:
				ops->rect(ctx, obj->x, obj->y,
				    obj->u.rect.ex, obj->u.rect.ey,
				    obj->color, obj->fill_color, objs->layer);
				break;
			case lo_poly:
				ops->poly(ctx, obj->u.poly.n,
				    obj->u.poly.vx, obj->u.poly.vy,
				    obj->color, obj->fill_color, objs->layer);
				break;
			case lo_circ:
				ops->circ(ctx, obj->x, obj->y,
				    obj->u.circ.r,
				    obj->color, obj->fill_color, objs->layer);
				break;
			case lo_arc:
				ops->arc(ctx, obj->x, obj->y, obj->u.arc.r,
				    obj->u.arc.sa, obj->u.arc.ea,
				    obj->color, obj->fill_color, objs->layer);
				break;
			case lo_text:
				ops->text(ctx, obj->x, obj->y, obj->u.text.s,
				    obj->u.text.size, obj->u.text.align,
				    obj->u.text.rot,
				    obj->color, objs->layer);
				break;
			default:
				abort();
			}
}


void layer_bbox(const struct layer *layer, int *x, int *y, int *w, int *h)
{
	if (x)
		*x = layer->xmin;
	if (y)
		*y = layer->ymin;
	if (w)
		*w = layer->xmax - layer->xmin + 1;
	if (h)
		*h = layer->ymax - layer->ymin + 1;
}


static void layer_obj_destroy(struct layer_obj *obj)
{
	switch (obj->type) {
	case lo_poly:
		free(obj->u.poly.vx);
		free(obj->u.poly.vy);
		break;
	case lo_text:
		free(obj->u.text.s);
		break;
	default:
		break;
	}
	free(obj);
}


void layer_destroy(struct layer *layer)
{
	struct layer_objs *next_objs;
	struct layer_obj *next_obj;

	while (layer->objs) {
		next_objs = layer->objs->next;
		while (layer->objs->obj) {
			next_obj = layer->objs->obj->next;
			layer_obj_destroy(layer->objs->obj);
			layer->objs->obj = next_obj;
		}
		free(layer->objs);
		layer->objs = next_objs;
	}
}