#include <glib.h>
#include <math.h>
#include <pango/pangocairo.h>
#include <pango/pango-font.h>
#include <pango/pango-types.h>

#include "draw.h"
#include "button.h"
#include "log.h"

static void layout_destroy(Layout *layout)
{
    if (layout->pl != NULL) g_object_unref(layout->pl);
    g_free(layout);
}

Drawable *draw_create(const char *font, int height, int left_pad, int right_pad, int top_pad, int line_w)
{
    Drawable *draw = g_malloc(sizeof(Drawable));
    g_assert_nonnull(draw);

    log_debug("Pango loading font description '%s'", font);
    draw->desc = pango_font_description_from_string(font);
    log_debug("Pango found matching font '%s'", pango_font_description_get_family(draw->desc));

    draw->height = height;
    draw->left_pad = left_pad;
    draw->right_pad = right_pad;
    draw->top_pad = top_pad;

    draw->line_w = line_w;
    draw->layouts = NULL;

    log_debug("Draw context created [height=%d, left_pad=%d, right_pad=%d, top_pad=%d, line_w=%d]", height, left_pad, right_pad, top_pad, line_w);

    return draw;
}

static void compute_width(Drawable *draw, Window *win, int *width, int *height)
{
    // FIXME: Does not work for scale != 1
    //double scale = window_get_scale(win);
    double scale = 1;

    int screen_width = win->con->screen_size->width;
    int screen_height = win->con->screen_size->height;

    *width  = round(screen_width - draw->right_pad - draw->left_pad * scale);
    *height = round(draw->height * scale);
}

void draw_paint(Drawable *draw, Window *win)
{
    // FIXME: Does not work for scale != 1
    //double scale = window_get_scale(win);
    double scale = 1;

    int width, height;
    compute_width(draw, win, &width, &height);

    cairo_surface_t *surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);

    cairo_t *cr = cairo_create(surface);
    cairo_set_fill_rule(cr, CAIRO_FILL_RULE_EVEN_ODD);
    cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);

    double degree = M_PI / 180.0;

    cairo_set_source_rgba(cr, draw->background.r, draw->background.g, draw->background.b, draw->background.a);

    // TODO: Here we should paint the shape of the bar, however there is a problem with the surface
    //       painted in the pixmap to mask the window shape in window_paint_corners.
    //
    //       This is caused by some difference between the two shapes (that should technically be the same)
    //       which causes a mismatch between the two layers and leaves some black pixels visible

    //int radius = height / 2;
    //cairo_arc(cr, radius, radius, radius, 90.0 * degree, 270 * degree);
    //cairo_arc(cr, width - radius, radius, radius, 270 * degree, 450 * degree);
    //cairo_fill(cr);

    cairo_paint(cr);

    int line_w = draw->line_w * scale;
    cairo_set_line_width(cr, line_w);

    for (GList *it = draw->layouts; it; it = it->next) {
        Layout *layout = it->data;

        int radius = layout->height / 2;

        Color color = layout->btn->color;
        cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
        cairo_new_sub_path(cr);
        cairo_arc(cr, layout->x + radius, layout->y + radius, radius, 90 * degree, 270 * degree);
        cairo_arc(cr, layout->x + layout->width - radius, layout->y + radius, radius, 270 * degree, 450 * degree);
        cairo_close_path(cr);
        cairo_fill(cr);

        color = layout->btn->line_color;
        cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
        cairo_new_sub_path(cr);
        cairo_arc(cr, layout->x + radius, layout->y + radius, radius - line_w , 90 * degree, 270 * degree);
        cairo_arc(cr, layout->x + layout->width - radius, layout->y + radius, radius - line_w, 270 * degree, 450 * degree);
        cairo_close_path(cr);
        cairo_stroke(cr);

        if (layout->btn->simple) {
            int text_x = layout->x + (layout->width / 2) - (layout->text_w / 2);
            int text_y = layout->y + (layout->height / 2) - (layout->text_h / 2);

            color = CAST(layout->btn, ButtonSimple)->text_color;
            cairo_set_source_rgba(cr, color.r, color.g, color.b, color.a);
            cairo_move_to(cr, text_x, text_y);

            pango_cairo_update_layout(cr, layout->pl);
            pango_cairo_show_layout(cr, layout->pl);
        }
    }

    cairo_destroy(cr);

    // TODO: Move these somewhere else
    window_move(win, draw->left_pad, draw->top_pad);
    window_resize(win, width, draw->height);

    window_paint_surface(win, surface, width, height);
    cairo_surface_destroy(surface);
}

static gint align_compare(gconstpointer a, gconstpointer b)
{
    PangoAlignment a_align = ((Button *)a)->align;
    PangoAlignment b_align = ((Button *)b)->align;

    if (a_align < b_align) return -1;
    if (a_align > b_align) return 1;
    return 0;
}

// Works only for simple buttons
static void layout_text(Layout *layout, PangoFontDescription *desc, double scale, int height, int radius)
{
    const char *text = CAST(layout->btn, ButtonSimple)->text;

    pango_layout_set_font_description(layout->pl, desc);
    pango_layout_set_text(layout->pl, text, -1);
    pango_layout_set_alignment(layout->pl, PANGO_ALIGN_CENTER);

    int text_w, text_h;
    pango_layout_get_pixel_size(layout->pl, &text_w, &text_h);

    layout->text_w = ceil(text_w / scale);
    layout->text_h = ceil(text_h / scale);

    // If there is only one glyph the button should be round
    size_t text_l = g_utf8_strlen(text, -1);

    layout->width = text_l == 1 ? height : layout->text_w + 2 * radius;
    layout->height = height;
}

void draw_compute_layout(Drawable *draw, Window *win, GList *btns)
{
    g_list_free_full(draw->layouts, (GDestroyNotify)layout_destroy);
    draw->layouts = NULL;

    // FIXME: Does not work for scale != 1
    //double scale = window_get_scale(win);
    double scale = 1;

    int width, height;
    compute_width(draw, win, &width, &height);

    int x = 0;
    int radius = height / 2;

    int sep = 10 * scale;
    int line_w = draw->line_w * scale;

    btns = g_list_sort(btns, align_compare);

    GList *adjust_center = NULL;
    GList *adjust_right = NULL;

    int end_xs[3] = { 0 };
    Button *prev = NULL;

    for (GList *it = btns; it; it = it->next) {
        Button *btn = it->data;

        Layout *layout = g_malloc(sizeof(Layout));
        layout->btn = btn;

        if (prev != NULL && prev->align == btn->align) x += sep;

        layout->x = x + btn->padding;
        layout->y = btn->padding;

        draw->layouts = g_list_prepend(draw->layouts, layout);

        if (!btn->simple) {
            ButtonGroup *group = CAST(btn, ButtonGroup);
            g_assert_nonnull(group->children);

            // If there is only one child treat a group like a single button
            if (group->children->next == NULL) {
                Button *child = group->children->data;
                g_assert_true(child->simple);
                layout->btn = child;
            } else {
                for (GList *it = group->children; it; it = it->next) {
                    Button *btn = it->data;
                    // Nested groups are not allowed
                    g_assert_true(btn->simple);

                    Layout *child = g_malloc(sizeof(Layout));
                    child->btn = btn;

                    child->x = x + btn->padding;
                    child->y = btn->padding;;

                    child->pl = pango_cairo_create_layout(window_get_context(win));
                    layout_text(child, draw->desc, scale, height, radius);

                    draw->layouts = g_list_prepend(draw->layouts, child);

                    x += child->width + line_w * 2;

                    child->width -= 2 * btn->padding;
                    child->height -= 2 * btn->padding;

                    if (it->next != NULL) x += sep;
                }

                layout->pl = NULL;
                layout->width = x - layout->x;
                layout->height = height;

                // FIXME: Temporary solution to make the antialiasing (or the circles not overlapping correctly) problem less noticeable

                bool fix_left = CAST(g_list_first(group->children)->data, Button)->padding == 0;
                bool fix_right = CAST(g_list_last(group->children)->data, Button)->padding == 0;

                if (fix_left) {
                    layout->x += 1;
                    layout->width -= 1;
                }
                if (fix_right) layout->width -= 1;
                goto end;
            }
        }

        layout->pl = pango_cairo_create_layout(window_get_context(win));
        layout_text(layout, draw->desc, scale, height, radius);
        x += layout->width + line_w * 2;

        layout->width -= 2 * btn->padding;
        layout->height -= 2 * btn->padding;

end:
        if (prev != NULL && prev->align != btn->align) {
            if (btn->align == PANGO_ALIGN_CENTER) adjust_center = draw->layouts;
            else if (btn->align == PANGO_ALIGN_RIGHT) adjust_right = draw->layouts;
        }

        prev = btn;
        end_xs[btn->align] = x;
    }

    draw->layouts = g_list_reverse(draw->layouts);

    int widths[3] = {
        end_xs[0],
        end_xs[1] - end_xs[0],
        end_xs[2] - MAX(end_xs[1], end_xs[0]),
    };

    int start_xs[3] = {
        0,
        end_xs[0],
        MAX(end_xs[1], end_xs[0]),
    };

    int center = round(width / 2);
    int center_off = (center - widths[1] / 2) - start_xs[1];
    log_debug("Aligning center layout [x=%d, off=%d]", center, center_off);

    for (GList *it = adjust_center; it != adjust_right; it = it->next) {
        Layout *layout = it->data;
        layout->x += center_off;
    }

    int right = width - widths[2];
    // The width is off by 2 line width
    int right_off = right - start_xs[2] + 2 * line_w;
    log_debug("Aligning right layout [x=%d, off=%d]", right, right_off);

    for (GList *it = adjust_right; it != NULL; it = it->next) {
        Layout *layout = it->data;
        layout->x += right_off;
    }

    log_debug("Updated layouts");
}

void draw_set_background(Drawable *draw, Color background)
{
    draw->background = background;
}

void draw_destroy(Drawable *draw)
{
    g_list_free_full(draw->layouts, (GDestroyNotify)layout_destroy);
    pango_font_description_free(draw->desc);
    g_free(draw);
}

// vim: ts=4 sw=4 et