/*
 * cairo.c - Cairo graphics back-end
 *
 * 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 <stdbool.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <math.h>

#include <cairo/cairo.h>
#include <cairo/cairo-pdf.h>

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


/*
 * FIG works with 1/1200 in
 * KiCad works with mil
 * 1 point = 1/72 in
 */

#define	DEFAULT_SCALE	(72.0 / 1200)


struct cairo_ctx {
	struct layer layer;	/* must be first */

	int xo, yo;
	float scale;

	cairo_t *cr;
	cairo_surface_t *s;

	const char *output_name;
};


static inline int cd(struct cairo_ctx *cc, int x)
{
	return x * cc->scale;
}


static inline int cx(struct cairo_ctx *cc, int x)
{
	return cc->xo + x * cc->scale;
}


static inline int xc(struct cairo_ctx *cc, int x)
{
	return (x - cc->xo) / cc->scale;
}


static inline int cy(struct cairo_ctx *cc, int y)
{
	return cc->yo + y * cc->scale;
}


static inline float pt(struct cairo_ctx *cc, int x)
{
	return cd(cc, x) * 72 * 1.5 / 1200.0;
}


static void set_color(cairo_t *cr, int color)
{
	uint32_t c;

	if (color < 0)
		return;
	c = color_rgb[color];
	cairo_set_source_rgb(cr, (c >> 16) / 255.0, ((c >> 8) & 255) / 255.0,
	    (c & 255) / 255.0);
}


static void paint(cairo_t *cr, int color, int fill_color)
{
	if (fill_color != COLOR_NONE) {
		set_color(cr, fill_color);
		if (color == COLOR_NONE)
			cairo_fill(cr);
		else
			cairo_fill_preserve(cr);
	}
	if (color != COLOR_NONE) {
		set_color(cr, color);
		cairo_stroke(cr);
	}
}


/* ----- General items ----------------------------------------------------- */


static void cr_poly(void *ctx, int points, int x[points], int y[points],
    int color, int fill_color, unsigned layer)
{
	struct cairo_ctx *cc = ctx;
	bool closed;
	int i;

	if (points < 2)
		return;
	closed = x[0] == x[points - 1] && y[0] == y[points - 1];

	cairo_new_path(cc->cr);
	cairo_move_to(cc->cr, cx(cc, x[0]), cy(cc, y[0]));

	for (i = 1; i != points - closed; i++)
		cairo_line_to(cc->cr, cx(cc, x[i]), cy(cc, y[i]));
	if (closed)
		cairo_close_path(cc->cr);

	paint(cc->cr, color, fill_color);
}


static void cr_circ(void *ctx, int x, int y, int r,
    int color, int fill_color, unsigned layer)
{
	struct cairo_ctx *cc = ctx;

	cairo_new_path(cc->cr);
	cairo_arc(cc->cr, cx(cc, x), cy(cc, y), cd(cc, r), 0, 2 * M_PI);
	paint(cc->cr, color, fill_color);
}


static void cr_arc(void *ctx, int x, int y, int r, int sa, int ea,
    int color, int fill_color, unsigned layer)
{
	struct cairo_ctx *cc = ctx;

	cairo_new_path(cc->cr);
	cairo_arc(cc->cr, cx(cc, x), cy(cc, y), cd(cc, r),
	    -ea / 180.0 * M_PI, -sa / 180.0 * M_PI);
	paint(cc->cr, color, fill_color);
}


#define	TEXT_STRETCH	1.3


static void cr_text(void *ctx, int x, int y, const char *s, unsigned size,
    enum text_align align, int rot, unsigned color, unsigned layer)
{
	struct cairo_ctx *cc = ctx;
	cairo_text_extents_t ext;
	cairo_matrix_t m;

	cairo_set_font_size(cc->cr, cd(cc, size) * TEXT_STRETCH);
	cairo_text_extents(cc->cr, s, &ext);

	set_color(cc->cr, color);

	cairo_move_to(cc->cr, cx(cc, x), cy(cc, y));

	cairo_get_matrix(cc->cr, &m);
	cairo_rotate(cc->cr, -rot / 180.0 * M_PI);

	switch (align) {
	case text_min:
		break;
	case text_mid:
		cairo_rel_move_to(cc->cr, -ext.width / 2.0, 0);
		break;
	case text_max:
		cairo_rel_move_to(cc->cr, -ext.width, 0);
		break;
	default:
		abort();
	}

	cairo_show_text(cc->cr, s);
	cairo_set_matrix(cc->cr, &m);
}


static unsigned cr_text_width(void *ctx, const char *s, unsigned size)
{
	struct cairo_ctx *cc = ctx;
	cairo_text_extents_t ext;

	cairo_set_font_size(cc->cr, cx(cc, size) * TEXT_STRETCH);
	cairo_text_extents(cc->cr, s, &ext);
	return xc(cc, ext.width);
}


/* ----- Initializatio and termination ------------------------------------- */


static const struct gfx_ops real_cairo_ops = {
	.name		= "cairo",
	// .line	= cr_line,	@@@ later
	.poly		= cr_poly,
	.circ		= cr_circ,
	.arc		= cr_arc,
	.text		= cr_text,
	.text_width	= cr_text_width,
};


static struct cairo_ctx *init_common(int argc, char *const *argv)
{
	struct cairo_ctx *cc;
	char c;

	cc = alloc_type(struct cairo_ctx);
	cc->xo = cc->yo = 0;
	cc->scale = DEFAULT_SCALE;

	cc->output_name = NULL;
	while ((c = getopt(argc, argv, "o:s:")) != EOF)
		switch (c) {
		case 'o':
			cc->output_name = optarg;
			break;
		case 's':
			cc->scale = atof(optarg) * DEFAULT_SCALE;
			break;
		default:
			usage(*argv);
		}

	layer_init(&cc->layer, &real_cairo_ops, cc);

	return cc;
}


static void *cr_png_init(int argc, char *const *argv)
{
	struct cairo_ctx *cc;

	cc = init_common(argc, argv);

	/* cr_text_width needs *something* to work with */

	cc->s = cairo_image_surface_create(CAIRO_FORMAT_RGB24, 16, 16);
	cc->cr = cairo_create(cc->s);

	return cc;
}


static void *cr_pdf_init(int argc, char *const *argv)
{
	struct cairo_ctx *cc;

	cc = init_common(argc, argv);

	/* cr_text_width needs *something* to work with */

	cc->s = cairo_pdf_surface_create(NULL, 16, 16);
	cc->cr = cairo_create(cc->s);

	return cc;
}


static void end_common(struct cairo_ctx *cc, int *w, int *h)
{
	int x, y;

	cairo_surface_destroy(cc->s);
	cairo_destroy(cc->cr);

	layer_bbox(&cc->layer, &x, &y, w, h);

//	fprintf(stderr, "%dx%d%+d%+d\n", *w, *h, x, y);
	cc->xo = -cd(cc, x);
	cc->yo = -cd(cc, y);
	*w = cd(cc, *w);
	*h = cd(cc, *h);
//	fprintf(stderr, "%dx%d%+d%+d\n", *w, *h, x, y);
}


static void cr_png_end(void *ctx)
{
	struct cairo_ctx *cc = ctx;
	int w, h;

	end_common(cc, &w, &h);

	cc->s = cairo_image_surface_create(CAIRO_FORMAT_RGB24, w, h);
	cc->cr = cairo_create(cc->s);

	set_color(cc->cr, COLOR_WHITE);
	cairo_paint(cc->cr);

	cairo_select_font_face(cc->cr, "Helvetica", CAIRO_FONT_SLANT_NORMAL,
	    CAIRO_FONT_WEIGHT_BOLD);
	cairo_set_line_width(cc->cr, 3);

	layer_replay(&cc->layer);
	layer_destroy(&cc->layer);

	if (cc->output_name)
		cairo_surface_write_to_png(cc->s, cc->output_name);
}


static void cr_pdf_end(void *ctx)
{
	struct cairo_ctx *cc = ctx;
	int w, h;

	end_common(cc, &w, &h);

	cc->s = cairo_pdf_surface_create(cc->output_name, w, h);
	cc->cr = cairo_create(cc->s);

	set_color(cc->cr, COLOR_WHITE);
	cairo_paint(cc->cr);

	cairo_select_font_face(cc->cr, "Helvetica", CAIRO_FONT_SLANT_NORMAL,
	    CAIRO_FONT_WEIGHT_BOLD);
	cairo_set_line_width(cc->cr, 3);

	layer_replay(&cc->layer);
	layer_destroy(&cc->layer);

	cairo_show_page(cc->cr);

	cairo_surface_destroy(cc->s);
	cairo_destroy(cc->cr);
}


/* ----- Operations -------------------------------------------------------- */


const struct gfx_ops cairo_png_ops = {
	.name		= "png",
	// .line	= cr_line,	@@@ later
	.poly		= layer_poly,
	.circ		= layer_circ,
	.arc		= layer_arc,
	.text		= layer_text,
	.text_width	= cr_text_width,
	.init		= cr_png_init,
	.end		= cr_png_end,
};

const struct gfx_ops cairo_pdf_ops = {
	.name		= "pdf",
	// .line	= cr_line,	@@@ later
	.poly		= layer_poly,
	.circ		= layer_circ,
	.arc		= layer_arc,
	.text		= layer_text,
	.text_width	= cr_text_width,
	.init		= cr_pdf_init,
	.end		= cr_pdf_end,
};