/*
 * sc_interp.c
 *
 * Copyright © 2014 Thomas White <taw@bitwiz.org.uk>
 *
 * This file is part of Colloquium.
 *
 * Colloquium 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <pango/pangocairo.h>
#include <gdk/gdk.h>

#include "sc_parse.h"
#include "sc_interp.h"
#include "shape.h"
#include "wrap.h"


struct sc_state
{
	PangoFontDescription *fontdesc;
	PangoFont *font;
	double col[4];
	int ascent;
	int height;

	struct frame *fr;  /* The current frame */
};


struct _scinterp
{
	PangoContext *pc;
	PangoLanguage *lang;

	struct slide_constants *s_constants;
	struct presentation_constants *p_constants;

	struct sc_state *state;
	int j;  /* Index of the current state */
	int max_state;

	struct wrap_line *boxes;
};


PangoFont *sc_interp_get_font(SCInterpreter *scin)
{
	struct sc_state *st = &scin->state[scin->j];
	return st->font;
}


PangoFontDescription *sc_interp_get_fontdesc(SCInterpreter *scin)
{
	struct sc_state *st = &scin->state[scin->j];
	return st->fontdesc;
}


double *sc_interp_get_fgcol(SCInterpreter *scin)
{
	struct sc_state *st = &scin->state[scin->j];
	return st->col;
}


int sc_interp_get_ascent(SCInterpreter *scin)
{
	struct sc_state *st = &scin->state[scin->j];
	return st->ascent;
}


int sc_interp_get_height(SCInterpreter *scin)
{
	struct sc_state *st = &scin->state[scin->j];
	return st->height;
}


static void set_font(SCInterpreter *scin, const char *font_name)
{
	PangoFontMetrics *metrics;
	struct sc_state *st = &scin->state[scin->j];

	st->fontdesc = pango_font_description_from_string(font_name);
	if ( st->fontdesc == NULL ) {
		fprintf(stderr, "Couldn't describe font.\n");
		return;
	}
	st->font = pango_font_map_load_font(pango_context_get_font_map(scin->pc),
	                                    scin->pc, st->fontdesc);
	if ( st->font == NULL ) {
		fprintf(stderr, "Couldn't load font.\n");
		return;
	}

	/* FIXME: Language for box */
	metrics = pango_font_get_metrics(st->font, NULL);
	st->ascent = pango_font_metrics_get_ascent(metrics);
	st->height = st->ascent + pango_font_metrics_get_descent(metrics);
	pango_font_metrics_unref(metrics);
}


/* This sets the colour for the font at the top of the stack */
static void set_colour(SCInterpreter *scin, const char *colour)
{
	GdkRGBA col;
	struct sc_state *st = &scin->state[scin->j];

	if ( colour == NULL ) {
		printf("Invalid colour\n");
		st->col[0] = 0.0;
		st->col[1] = 0.0;
		st->col[2] = 0.0;
		st->col[3] = 1.0;
		return;
	}

	gdk_rgba_parse(&col, colour);

	st->col[0] = col.red;
	st->col[1] = col.green;
	st->col[2] = col.blue;
	st->col[3] = col.alpha;
}


void sc_interp_save(SCInterpreter *scin)
{
	if ( scin->j+1 == scin->max_state ) {

		struct sc_state *stack_new;

		stack_new = realloc(scin->state, sizeof(struct sc_state)
		                     * (scin->max_state+8));
		if ( stack_new == NULL ) {
			fprintf(stderr, "Failed to add to stack.\n");
			return;
		}

		scin->state = stack_new;
		scin->max_state += 8;

	}

	/* When n_fonts=0, we leave the first font uninitialised.  This allows
	 * the stack to be "bootstrapped", but requires the first caller to do
	 * set_font and set_colour straight away. */
	scin->state[scin->j+1] = scin->state[scin->j];
	scin->j++;
}


void sc_interp_restore(SCInterpreter *scin)
{
	struct sc_state *st = &scin->state[scin->j];

	if ( scin->j > 0 ) {
		if ( st->fontdesc != scin->state[scin->j-1].fontdesc )
		{
			pango_font_description_free(st->fontdesc);
		} /* else the font is the same as the previous one, and we
		   * don't need to free it just yet */
	}

	scin->j--;
}


struct frame *sc_interp_get_frame(SCInterpreter *scin)
{
	struct sc_state *st = &scin->state[scin->j];
	return st->fr;
}


static void set_frame(SCInterpreter *scin, struct frame *fr)
{
	struct sc_state *st = &scin->state[scin->j];
	st->fr = fr;
}


SCInterpreter *sc_interp_new(PangoContext *pc, struct frame *top)
{
	SCInterpreter *scin;

	scin = malloc(sizeof(SCInterpreter));
	if ( scin == NULL ) return NULL;

	scin->state = malloc(8*sizeof(struct sc_state));
	if ( scin->state == NULL ) {
		free(scin);
		return NULL;
	}
	scin->j = 0;
	scin->max_state = 8;

	scin->pc = pc;
	scin->s_constants = NULL;
	scin->p_constants = NULL;

	/* FIXME: Determine proper language (somehow...) */
	scin->lang = pango_language_from_string("en_GB");

	scin->boxes = malloc(sizeof(struct wrap_line));
	if ( scin->boxes == NULL ) {
		fprintf(stderr, "Failed to allocate boxes.\n");
		return NULL;
	}
	initialise_line(scin->boxes);

	/* The "ultimate" default font */
	set_font(scin, "Sans 12");
	set_colour(scin, "#000000");
	set_frame(scin, top);

	return scin;
}


void sc_interp_destroy(SCInterpreter *scin)
{
	/* Empty the stack */
	while ( scin->j > 0 ) {
		sc_interp_restore(scin);
	}

	pango_font_description_free(scin->state[0].fontdesc);

	free(scin);
}


static LengthUnits get_units(const char *t)
{
	size_t len = strlen(t);

	if ( t[len-1] == 'f' ) return UNITS_FRAC;
	if ( t[len-1] == 'u' ) return UNITS_SLIDE;

	fprintf(stderr, "Invalid units in '%s'\n", t);
	return UNITS_SLIDE;
}


static void parse_frame_option(struct frame *fr, const char *opt)
{
	if ( (index(opt, 'x') != NULL) && (index(opt, '+') != NULL)
	  && (index(opt, '+') != rindex(opt, '+')) )
	{
		char *w;
		char *h;
		char *x;
		char *y;
		char *check;
		LengthUnits h_units, w_units;

		/* Looks like a dimension/position thing */
		w = strdup(opt);
		h = index(w, 'x');
		h[0] = '\0';  h++;

		x = index(h, '+');
		if ( x == NULL ) {
			fprintf(stderr, "Invalid option '%s'\n", opt);
			return;
		}
		x[0] = '\0';  x++;

		y = index(x, '+');
		if ( x == NULL ) {
			fprintf(stderr, "Invalid option '%s'\n", opt);
			return;
		}
		y[0] = '\0';  y++;

		fr->w = strtod(w, &check);
		if ( check == w ) {
			fprintf(stderr, "Invalid option '%s'\n", opt);
			return;
		}
		w_units = get_units(w);

		fr->h = strtod(h, &check);
		if ( check == h ) {
			fprintf(stderr, "Invalid option '%s'\n", opt);
			return;
		}
		h_units = get_units(h);
		/* FIXME: Handle units */

		fr->x = strtod(x, &check);
		if ( check == x ) {
			fprintf(stderr, "Invalid option '%s'\n", opt);
			return;
		}
		fr->y = strtod(y, &check);
		if ( check == y ) {
			fprintf(stderr, "Invalid option '%s'\n", opt);
			return;
		}

	}
}


static void parse_frame_options(struct frame *fr, const char *opth)
{
	int i;
	size_t len;
	size_t start;
	char *opt;

	if ( opth == NULL ) return;

	opt = strdup(opth);

	len = strlen(opt);
	start = 0;

	for ( i=0; i<len; i++ ) {

		/* FIXME: comma might be escaped or quoted */
		if ( opt[i] == ',' ) {
			opt[i] = '\0';
			parse_frame_option(fr, opt+start);
			start = i+1;
		}

	}

	if ( start != len ) {
		parse_frame_option(fr, opt+start);
	}

	free(opt);
}


int sc_interp_add_blocks(SCInterpreter *scin, SCBlock *bl)
{
	while ( bl != NULL ) {

		const char *name = sc_block_name(bl);
		const char *options = sc_block_options(bl);
		const char *contents = sc_block_contents(bl);
		SCBlock *child = sc_block_child(bl);

		if ( child != NULL ) {
			sc_interp_save(scin);
		}

		if ( name == NULL ) {
			split_words(scin->boxes, scin->pc, contents,
			            scin->lang, 1, scin);

		} else if ( strcmp(name, "font") == 0 ) {
			set_font(scin, options);

		} else if ( strcmp(name, "fgcol") == 0 ) {
			set_colour(scin, options);

#if 0
		} else if ( strcmp(name, "image")==0 ) {
			int w, h;
			if ( get_size(options, fr, &w, &h) == 0 ) {
				add_image_box(boxes, b->contents, offset, w, h,
				              editable);
			}

		} else if ( strcmp(name, "slidenumber")==0) {
			char *tmp = malloc(64);
			if ( tmp != NULL ) {
				snprintf(tmp, 63, "%i",
				         slide_constants->slide_number);
				add_wrap_box(boxes, tmp, offset,
					     WRAP_SPACE_NONE, pc,
					     &fonts->stack[fonts->n_fonts-1],
			                     0);
			} /* else go away and sulk about it */
#endif

		} else if ( strcmp(name, "f")==0 ) {
			struct frame *fr = sc_block_frame(bl);
			if ( fr == NULL ) {
				fr = add_subframe(sc_interp_get_frame(scin));
				sc_block_set_frame(bl, fr);
				fr->scblocks = child;
			}
			if ( fr == NULL ) {
				fprintf(stderr, "Failed to add frame.\n");
				goto next;
			}
			parse_frame_options(fr, options);
			set_frame(scin, fr);

		} else {

			fprintf(stderr, "Don't know what to do with this:\n");
			show_sc_block(bl, "");

		}

next:
		if ( child != NULL ) {
			sc_interp_add_blocks(scin, child);
			sc_interp_restore(scin);
		}
		bl = sc_block_next(bl);

	}

	return 0;
}


struct wrap_line *sc_interp_get_boxes(SCInterpreter *scin)
{
	return scin->boxes;
}