#include <cairo/cairo.h>
#include <math.h>
#include <unistd.h>
#include "entry.h"
#include "log.h"
#include "nelem.h"
#include "scale.h"

#undef MAX
#define MAX(a, b) ((a) > (b) ? (a) : (b))

static void rounded_rectangle(cairo_t *cr, uint32_t width, uint32_t height, uint32_t r)
{
	cairo_new_path(cr);

	/* Top-left */
	cairo_arc(cr, r, r, r, -M_PI, -M_PI_2);

	/* Top-right */
	cairo_arc(cr, width - r, r, r, -M_PI_2, 0);

	/* Bottom-right */
	cairo_arc(cr, width - r, height - r, r, 0, M_PI_2);

	/* Bottom-left */
	cairo_arc(cr, r, height - r, r, M_PI_2, M_PI);

	cairo_close_path(cr);
}

static void apply_text_theme_fallback(struct text_theme *theme, const struct text_theme *fallback)
{
	if (!theme->foreground_specified) {
		theme->foreground_color = fallback->foreground_color;
	}
	if (!theme->background_specified) {
		theme->background_color = fallback->background_color;
	}
	if (!theme->padding_specified) {
		theme->padding = fallback->padding;
	}
	if (!theme->radius_specified) {
		theme->background_corner_radius = fallback->background_corner_radius;
	}
}

void entry_init(struct entry *entry, uint8_t *restrict buffer, uint32_t width, uint32_t height, uint32_t fractional_scale_numerator)
{
	double scale = fractional_scale_numerator / 120.;
	/*
	 * Create the cairo surfaces and contexts we'll be using.
	 *
	 * In order to avoid an unnecessary copy when passing the image to the
	 * Wayland server, we accept a pointer to the mmap-ed file that our
	 * Wayland buffers are created from. This is assumed to be
	 * (width * height * (sizeof(uint32_t) == 4) * 2) bytes,
	 * to allow for double buffering.
	 */
	log_debug("Creating %u x %u Cairo surface with scale factor %.3lf.\n",
			width,
			height,
			fractional_scale_numerator / 120.);
	cairo_surface_t *surface = cairo_image_surface_create_for_data(
			buffer,
			CAIRO_FORMAT_ARGB32,
			width,
			height,
			width * sizeof(uint32_t)
			);
	cairo_surface_set_device_scale(surface, scale, scale);
	cairo_t *cr = cairo_create(surface);

	entry->cairo[0].surface = surface;
	entry->cairo[0].cr = cr;

	entry->cairo[1].surface = cairo_image_surface_create_for_data(
			&buffer[width * height * sizeof(uint32_t)],
			CAIRO_FORMAT_ARGB32,
			width,
			height,
			width * sizeof(uint32_t)
			);
	cairo_surface_set_device_scale(entry->cairo[1].surface, scale, scale);
	entry->cairo[1].cr = cairo_create(entry->cairo[1].surface);

	/* If we're scaling with Cairo, remember to account for that here. */
	width = scale_apply_inverse(width, fractional_scale_numerator);
	height = scale_apply_inverse(height, fractional_scale_numerator);

	log_debug("Drawing window.\n");
	/* Draw the background */
	struct color color = entry->background_color;
	cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
	cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
	cairo_paint(cr);

	/* Draw the border with outlines */
	cairo_set_line_width(cr, 4 * entry->outline_width + 2 * entry->border_width);
	rounded_rectangle(cr, width, height, entry->corner_radius);

	color = entry->outline_color;
	cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
	cairo_stroke_preserve(cr);

	color = entry->border_color;
	cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
	cairo_set_line_width(cr, 2 * entry->outline_width + 2 * entry->border_width);
	cairo_stroke_preserve(cr);

	color = entry->outline_color;
	cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
	cairo_set_line_width(cr, 2 * entry->outline_width);
	cairo_stroke_preserve(cr);

	/* Clear the overdrawn bits outside of the rounded corners */
	/*
	 * N.B. the +1's shouldn't be required, but certain fractional scale
	 * factors can otherwise cause 1-pixel artifacts on the edges
	 * (presumably because Cairo is performing rounding differently to us
	 * at some point).
	 */
	cairo_rectangle(cr, 0, 0, width + 1, height + 1);
	cairo_set_source_rgba(cr, 0, 0, 0, 1);
	cairo_save(cr);
	cairo_set_fill_rule(cr, CAIRO_FILL_RULE_EVEN_ODD);
	cairo_set_operator(cr, CAIRO_OPERATOR_CLEAR);
	cairo_fill(cr);
	cairo_restore(cr);

	cairo_set_operator(cr, CAIRO_OPERATOR_OVER);


	/* Move and clip following draws to be within this outline */
	double dx = 2.0 * entry->outline_width + entry->border_width;
	cairo_translate(cr, dx, dx);
	width -= 2 * dx;
	height -= 2 * dx;

	/* If we're clipping to the padding, account for that as well here */
	if (entry->clip_to_padding) {
		cairo_translate(cr, entry->padding_left, entry->padding_top);
		width -= entry->padding_left + entry->padding_right;
		height -= entry->padding_top + entry->padding_bottom;
	}

	/* Account for rounded corners */
	double inner_radius = (double)entry->corner_radius - dx;
	inner_radius = MAX(inner_radius, 0);

	dx = ceil(inner_radius * (1.0 - 1.0 / M_SQRT2));
	cairo_translate(cr, dx, dx);
	width -= 2 * dx;
	height -= 2 * dx;
	cairo_rectangle(cr, 0, 0, width, height);
	cairo_clip(cr);

	/* Store the clip rectangle width and height. */
	cairo_matrix_t mat;
	cairo_get_matrix(cr, &mat);
	entry->clip_x = mat.x0;
	entry->clip_y = mat.y0;
	entry->clip_width = width;
	entry->clip_height = height;

	/*
	 * If we're not clipping to the padding, we didn't account for it
	 * before.
	 */
	if (!entry->clip_to_padding) {
		cairo_translate(cr, entry->padding_left, entry->padding_top);
	}

	/* Setup the backend. */
	if (access(entry->font_name, R_OK) != 0) {
		/*
		 * We've been given a font name rather than path,
		 * so fallback to Pango
		 */
		entry->use_pango = true;
	}
	if (entry->use_pango) {
		entry_backend_pango_init(entry, &width, &height);
	} else {
		entry_backend_harfbuzz_init(entry, &width, &height);
	}

        /*
	 * Before we render any text, ensure all text themes are fully
	 * specified.
	 */
        const struct text_theme default_theme = {
		.foreground_color = entry->foreground_color,
		.background_color = (struct color) { .a = 0 },
		.padding = (struct directional) {0},
		.background_corner_radius = 0
	};

	apply_text_theme_fallback(&entry->prompt_theme, &default_theme);
	apply_text_theme_fallback(&entry->input_theme, &default_theme);
	apply_text_theme_fallback(&entry->placeholder_theme, &default_theme);
	apply_text_theme_fallback(&entry->default_result_theme, &default_theme);
	apply_text_theme_fallback(&entry->alternate_result_theme, &entry->default_result_theme);
	apply_text_theme_fallback(&entry->selection_theme, &default_theme);

	/* The cursor is a special case, as it just needs the input colours. */
	if (!entry->cursor_theme.color_specified) {
		entry->cursor_theme.color = entry->input_theme.foreground_color;
	}
	if (!entry->cursor_theme.text_color_specified) {
		entry->cursor_theme.text_color = entry->background_color;
	}

	/*
	 * Perform an initial render of the text.
	 * This is done here rather than by calling entry_update to avoid the
	 * unnecessary cairo_paint() of the background for the first frame,
	 * which can be slow for large (e.g. fullscreen) windows.
	 */
	log_debug("Initial text render.\n");
	if (entry->use_pango) {
		entry_backend_pango_update(entry);
	} else {
		entry_backend_harfbuzz_update(entry);
	}
	entry->index = !entry->index;

	/*
	 * To avoid performing all this drawing twice, we take a small
	 * shortcut. After performing all the drawing as normal on our first
	 * Cairo context, we can copy over just the important state (the
	 * transformation matrix and clip rectangle) and perform a memcpy()
	 * to initialise the other context.
	 *
	 * This memcpy can pretty expensive however, and isn't needed until
	 * we need to draw our second buffer (i.e. when the user presses a
	 * key). In order to minimise startup time, the memcpy() isn't
	 * performed here, but instead happens later, just after the first
	 * frame has been displayed on screen (and while the user is unlikely
	 * to press another key for the <10ms it takes to memcpy).
	 */
	cairo_set_matrix(entry->cairo[1].cr, &mat);
	cairo_rectangle(entry->cairo[1].cr, 0, 0, width, height);
	cairo_clip(entry->cairo[1].cr);

	/*
	 * If we're not clipping to the padding, the transformation matrix
	 * didn't include it, so account for it here.
	 */
	if (!entry->clip_to_padding) {
		cairo_translate(entry->cairo[1].cr, entry->padding_left, entry->padding_top);
	}
}

void entry_destroy(struct entry *entry)
{
	if (entry->use_pango) {
		entry_backend_pango_destroy(entry);
	} else {
		entry_backend_harfbuzz_destroy(entry);
	}
	cairo_destroy(entry->cairo[0].cr);
	cairo_destroy(entry->cairo[1].cr);
	cairo_surface_destroy(entry->cairo[0].surface);
	cairo_surface_destroy(entry->cairo[1].surface);
}

void entry_update(struct entry *entry)
{
	log_debug("Start rendering entry.\n");
	cairo_t *cr = entry->cairo[entry->index].cr;

	/* Clear the image. */
	struct color color = entry->background_color;
	cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
	cairo_save(cr);
	cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
	cairo_paint(cr);
	cairo_restore(cr);

	/* Draw our text. */
	if (entry->use_pango) {
		entry_backend_pango_update(entry);
	} else {
		entry_backend_harfbuzz_update(entry);
	}

	log_debug("Finish rendering entry.\n");

	entry->index = !entry->index;
}