#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <time.h>

#include "dive.h"
#include "display.h"
#include "divelist.h"

int selected_dive = 0;

/*
 * Cairo scaling really is horribly horribly mis-designed.
 *
 * Which is sad, because I really like Cairo otherwise. But
 * the fact that the line width is scaled with the same scale
 * as the coordinate system is a f*&%ing disaster. So we
 * can't use it, and instead have this butt-ugly wrapper thing..
 */
struct graphics_context {
	cairo_t *cr;
	double maxx, maxy;
	double scalex, scaley;
};

/* Scale to 0,0 -> maxx,maxy */
#define SCALE(gc,x,y) (x)*gc->maxx/gc->scalex,(y)*gc->maxy/gc->scaley

static void move_to(struct graphics_context *gc, double x, double y)
{
	cairo_move_to(gc->cr, SCALE(gc, x, y));
}

static void line_to(struct graphics_context *gc, double x, double y)
{
	cairo_line_to(gc->cr, SCALE(gc, x, y));
}

#define ROUND_UP(x,y) ((((x)+(y)-1)/(y))*(y))

/*
 * When showing dive profiles, we scale things to the
 * current dive. However, we don't scale past less than
 * 30 minutes or 90 ft, just so that small dives show
 * up as such.
 */
static int round_seconds_up(int seconds)
{
	return MAX(30*60, ROUND_UP(seconds, 60*10));
}

static int round_depth_up(depth_t depth)
{
	unsigned mm = depth.mm;
	/* Minimum 30m */
	return MAX(30000, ROUND_UP(mm+3000, 10000));
}

typedef struct {
	double r,g,b;
	enum {CENTER,LEFT} halign;
	enum {MIDDLE,TOP,BOTTOM} valign;
} text_render_options_t;

static void plot_text(struct graphics_context *gc, text_render_options_t *tro,
		      double x, double y, const char *fmt, ...)
{
	cairo_t *cr = gc->cr;
	cairo_text_extents_t extents;
	double dx, dy;
	char buffer[80];
	va_list args;

	va_start(args, fmt);
	vsnprintf(buffer, sizeof(buffer), fmt, args);
	va_end(args);

	cairo_text_extents(cr, buffer, &extents);
	dx = 0;
	switch (tro->halign) {
	case CENTER:
		dx = -(extents.width/2 + extents.x_bearing);
		break;
	case LEFT:
		dx = 0;
		break;
	}
	switch (tro->valign) {
	case TOP:
		dy = extents.height * 1.2;
		break;
	case BOTTOM:
		dy = -extents.height * 0.8;
		break;
	case MIDDLE:
		dy = 0;
		break;
	}

	move_to(gc, x, y);
	cairo_rel_move_to(cr, dx, dy);

	cairo_text_path(cr, buffer);
	cairo_set_source_rgb(cr, 0, 0, 0);
	cairo_stroke(cr);

	move_to(gc, x, y);
	cairo_rel_move_to(cr, dx, dy);

	cairo_set_source_rgb(cr, tro->r, tro->g, tro->b);
	cairo_show_text(cr, buffer);
}

/*
 * Find the next minimum/maximum point.
 *
 * We exit early if we hit "enough" of a depth reversal,
 * which is roughly 10 feet.
 */
static struct sample *next_minmax(struct sample *sample, struct sample *end, int minmax)
{
	const int enough = 3000;
	struct sample *result;
	int depthlimit;

	if (sample >= end)
		return 0;

	depthlimit = sample->depth.mm;
	result = NULL;

	for (;;) {
		int time, depth;

		sample++;
		if (sample >= end)
			return NULL;
		time = sample->time.seconds;
		depth = sample->depth.mm;

		if (minmax) {
			if (depth <= depthlimit) {
				if (depthlimit - depth > enough)
					break;
				continue;
			}
		} else {
			if (depth >= depthlimit) {
				if (depth - depthlimit > enough)
					break;
				continue;
			}
		}

		result = sample;
		depthlimit = depth;
	}
	return result;
}

static void render_depth_sample(struct graphics_context *gc, struct sample *sample)
{
	text_render_options_t tro = {1.0, 0.2, 0.2, CENTER, TOP};
	int sec = sample->time.seconds;
	depth_t depth = sample->depth;
	const char *fmt;
	double d;

	switch (output_units.length) {
	case METERS:
		d = depth.mm / 1000.0;
		fmt = "%.1f";
		break;
	case FEET:
		d = to_feet(depth);
		fmt = "%.0f";
		break;
	}
	plot_text(gc, &tro, sec, depth.mm, fmt, d);
}

static void plot_text_samples(struct graphics_context *gc, struct sample *a, struct sample *b)
{
	for (;;) {
		if (b <= a)
			break;
		a = next_minmax(a, b, 1);
		if (!a)
			return;
		render_depth_sample(gc, a);
		a = next_minmax(a, b, 0);
		if (!a)
			break;
	}
}

static void plot_depth_text(struct dive *dive, struct graphics_context *gc)
{
	struct sample *sample, *end;
	int maxtime, maxdepth;

	/* Get plot scaling limits */
	maxtime = round_seconds_up(dive->duration.seconds);
	maxdepth = round_depth_up(dive->maxdepth);

	gc->scalex = maxtime;
	gc->scaley = maxdepth;

	cairo_set_font_size(gc->cr, 14);

	sample = dive->sample;
	end = dive->sample + dive->samples;

	plot_text_samples(gc, sample, end);
}

static void plot_depth_profile(struct dive *dive, struct graphics_context *gc)
{
	cairo_t *cr = gc->cr;
	int begins, sec, depth;
	int i, samples;
	struct sample *sample;
	int maxtime, maxdepth, marker;

	samples = dive->samples;
	if (!samples)
		return;

	cairo_set_line_width(gc->cr, 2);

	/* Get plot scaling limits */
	maxtime = round_seconds_up(dive->duration.seconds);
	maxdepth = round_depth_up(dive->maxdepth);

	/* Time markers: every 5 min */
	gc->scalex = maxtime;
	gc->scaley = 1.0;
	for (i = 5*60; i < maxtime; i += 5*60) {
		move_to(gc, i, 0);
		line_to(gc, i, 1);
	}

	/* Depth markers: every 30 ft or 10 m*/
	gc->scalex = 1.0;
	gc->scaley = maxdepth;
	switch (output_units.length) {
	case METERS: marker = 10000; break;
	case FEET: marker = 9144; break;	/* 30 ft */
	}

	cairo_set_source_rgba(cr, 1, 1, 1, 0.5);
	for (i = marker; i < maxdepth; i += marker) {
		move_to(gc, 0, i);
		line_to(gc, 1, i);
	}
	cairo_stroke(cr);

	/* Show mean depth */
	cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.40);
	move_to(gc, 0, dive->meandepth.mm);
	line_to(gc, 1, dive->meandepth.mm);
	cairo_stroke(cr);

	gc->scalex = maxtime;

	sample = dive->sample;
	cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.80);
	begins = sample->time.seconds;
	move_to(gc, sample->time.seconds, sample->depth.mm);
	for (i = 1; i < dive->samples; i++) {
		sample++;
		sec = sample->time.seconds;
		if (sec <= maxtime) {
			depth = sample->depth.mm;
			line_to(gc, sec, depth);
		}
	}
	gc->scaley = 1.0;
	line_to(gc, MIN(sec,maxtime), 0);
	line_to(gc, begins, 0);
	cairo_close_path(cr);
	cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.20);
	cairo_fill_preserve(cr);
	cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.80);
	cairo_stroke(cr);
}

/* gets both the actual start and end pressure as well as the scaling factors */
static int get_cylinder_pressure_range(struct dive *dive, struct graphics_context *gc,
	pressure_t *startp, pressure_t *endp)
{
	int i;
	int min, max;

	gc->scalex = round_seconds_up(dive->duration.seconds);

	max = 0;
	min = 5000000;
	if (startp)
		startp->mbar = endp->mbar = 0;

	for (i = 0; i < dive->samples; i++) {
		int mbar;
		struct sample *sample = dive->sample + i;

		/* FIXME! We only track cylinder 0 right now */
		if (sample->cylinderindex)
			continue;
		mbar = sample->cylinderpressure.mbar;
		if (!mbar)
			continue;
		if (mbar < min)
			min = mbar;
		if (mbar > max)
			max = mbar;
	}
	if (startp)
		startp->mbar = max;
	if (endp)
		endp->mbar = min;
	if (!max)
		return 0;
	gc->scaley = max * 1.5;
	return 1;
}

static void plot_cylinder_pressure(struct dive *dive, struct graphics_context *gc)
{
	int i, sec = -1;

	if (!get_cylinder_pressure_range(dive, gc, NULL, NULL))
		return;

	cairo_set_source_rgba(gc->cr, 0.2, 1.0, 0.2, 0.80);

	move_to(gc, 0, dive->cylinder[0].start.mbar);
	for (i = 1; i < dive->samples; i++) {
		int mbar;
		struct sample *sample = dive->sample + i;

		mbar = sample->cylinderpressure.mbar;
		if (!mbar)
			continue;
		sec = sample->time.seconds;
		if (sec <= dive->duration.seconds)
			line_to(gc, sec, mbar);
	}
	/*
	 * We may have "surface time" events, in which case we don't go
	 * back to dive duration
	 */
	if (sec < dive->duration.seconds)
		line_to(gc, dive->duration.seconds, dive->cylinder[0].end.mbar);
	cairo_stroke(gc->cr);
}

/*
 * Return air usage (in liters).
 */
static double calculate_airuse(struct dive *dive)
{
	double airuse = 0;
	int i;

	for (i = 0; i < MAX_CYLINDERS; i++) {
		cylinder_t *cyl = dive->cylinder + i;
		int size = cyl->type.size.mliter;
		double kilo_atm;

		if (!size)
			continue;

		kilo_atm = (cyl->start.mbar - cyl->end.mbar) / 1013250.0;

		/* Liters of air at 1 atm == milliliters at 1k atm*/
		airuse += kilo_atm * size;
	}
	return airuse;
}

static void plot_info(struct dive *dive, struct graphics_context *gc)
{
	text_render_options_t tro = {0.2, 1.0, 0.2, LEFT, TOP};
	const double liters_per_cuft = 28.317;
	const char *unit;
	double airuse;

	airuse = calculate_airuse(dive);
	if (!airuse)
		return;

	/* I really need to start addign some unit setting thing */
	switch (output_units.volume) {
	case LITER:
		unit = "l";
		break;
	case CUFT:
		unit = "cuft";
		airuse /= liters_per_cuft;
		break;
	}
	plot_text(gc, &tro, 0.8, 0.8, "vol: %4.2f %s", airuse, unit);
	if (dive->duration.seconds) {
		double pressure = 1 + (dive->meandepth.mm / 10000.0);
		double sac = airuse / pressure * 60 / dive->duration.seconds;
		plot_text(gc, &tro, 0.8, 0.85, "SAC: %4.2f %s/min", sac, unit);
	}
}

static void plot_cylinder_pressure_text(struct dive *dive, struct graphics_context *gc)
{
	pressure_t startp, endp;

	cairo_set_font_size(gc->cr, 10);

	if (get_cylinder_pressure_range(dive, gc, &startp, &endp)) {
		int start, end;
		const char *unit = "bar";

		switch (output_units.pressure) {
		case PASCAL:
			start = startp.mbar * 100;
			end = startp.mbar * 100;
			unit = "pascal";
			break;
		case BAR:
			start = (startp.mbar + 500) / 1000;
			end = (endp.mbar + 500) / 1000;
			unit = "bar";
			break;
		case PSI:
			start = to_PSI(startp);
			end = to_PSI(endp);
			unit = "psi";
			break;
		}

		text_render_options_t tro = {0.2, 1.0, 0.2, LEFT, TOP};
		plot_text(gc, &tro, 0, startp.mbar, "%d %s", start, unit);
		plot_text(gc, &tro, dive->duration.seconds, endp.mbar,
			  "%d %s", end, unit);
	}
}

static void plot(struct graphics_context *gc, int w, int h, struct dive *dive)
{
	double topx, topy;

	topx = w / 20.0;
	topy = h / 20.0;
	cairo_translate(gc->cr, topx, topy);

	/*
	 * We can use "cairo_translate()" because that doesn't
	 * scale line width etc. But the actual scaling we need
	 * do set up ourselves..
	 *
	 * Snif. What a pity.
	 */
	gc->maxx = (w - 2*topx);
	gc->maxy = (h - 2*topy);

	/* Cylinder pressure plot */
	plot_cylinder_pressure(dive, gc);

	/* Depth profile */
	plot_depth_profile(dive, gc);

	/* Text on top of all graphs.. */
	plot_depth_text(dive, gc);
	plot_cylinder_pressure_text(dive, gc);

	/* And info box in the lower right corner.. */
	gc->scalex = gc->scaley = 1.0;
	plot_info(dive, gc);

	/* Bounding box last */
	cairo_set_source_rgb(gc->cr, 1, 1, 1);
	move_to(gc, 0, 0);
	line_to(gc, 0, 1);
	line_to(gc, 1, 1);
	line_to(gc, 1, 0);
	cairo_close_path(gc->cr);
	cairo_stroke(gc->cr);

}

static gboolean expose_event(GtkWidget *widget, GdkEventExpose *event, gpointer data)
{
	struct dive *dive = current_dive;
	struct graphics_context gc;
	int w,h;

	w = widget->allocation.width;
	h = widget->allocation.height;

	gc.cr = gdk_cairo_create(widget->window);
	cairo_set_source_rgb(gc.cr, 0, 0, 0);
	cairo_paint(gc.cr);

	if (dive)
		plot(&gc, w, h, dive);

	cairo_destroy(gc.cr);

	return FALSE;
}

GtkWidget *dive_profile_widget(void)
{
	GtkWidget *da;

	da = gtk_drawing_area_new();
	gtk_widget_set_size_request(da, 450, 350);
	g_signal_connect(da, "expose_event", G_CALLBACK(expose_event), NULL);

	return da;
}