#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_list_free_full(layout->children, (GDestroyNotify)layout_destroy);
    g_free(layout);
}

Drawer *draw_create(const char *font, int height, int left_pad, int right_pad, int top_pad)
{
    Drawer *draw = g_malloc(sizeof(Drawer));
    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->layouts = NULL;

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

    return draw;
}

// TODO: Remove this
static void compute_width(Drawer *draw, Window *win, int *width, int *height)
{
    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);
    *height = round(draw->height);
}

static void paint_button(cairo_t *cr, const Layout *layout)
{
    double degree = M_PI / 180.0;
    int radius = (layout->height - 2 * layout->y_pad) / 2;
    int line_radius = radius - layout->line_w / 2;

    //// Layout size
    //cairo_set_source_rgb(cr, 0, 0, 0);
    //cairo_move_to(cr, layout->x, layout->y);
    //cairo_line_to(cr, layout->x, layout->y + layout->height);
    //cairo_stroke(cr);

    //cairo_move_to(cr, layout->x + layout->width, layout->y);
    //cairo_line_to(cr, layout->x + layout->width, layout->y + layout->height);
    //cairo_stroke(cr);

    //// Layout padding
    //cairo_set_source_rgb(cr, 0.5, 0.1, 0.1);
    //cairo_rectangle(cr, layout->x + layout->x_pad, layout->y + layout->y_pad, layout->width - 2 * layout->x_pad, layout->height - 2 * layout->y_pad);
    //cairo_stroke(cr);

    cairo_set_line_width(cr, layout->line_w);

    // Button background
    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 + layout->x_pad + radius, layout->y + layout->y_pad + radius, radius, 90 * degree, 270 * degree);
    cairo_arc(cr, layout->x + layout->width - layout->x_pad - radius, layout->y + layout->y_pad + radius, radius, 270 * degree, 450 * degree);
    cairo_close_path(cr);
    cairo_fill(cr);

    // Button border
    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 + layout->x_pad + radius, layout->y + layout->y_pad + radius, line_radius, 90 * degree, 270 * degree);
    cairo_arc(cr, layout->x + layout->width - layout->x_pad - radius, layout->y + layout->y_pad + radius, line_radius, 270 * degree, 450 * degree);
    cairo_close_path(cr);
    cairo_stroke(cr);
}

static void paint_text(cairo_t *cr, const Layout *layout)
{
    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 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);

    // NOTE: This works only if the text didn't change in size after the layouting
    pango_layout_set_text(layout->pl, CAST(layout->btn, ButtonSimple)->text, -1);
    pango_cairo_update_layout(cr, layout->pl);
    pango_cairo_show_layout(cr, layout->pl);
}

static void paint_button_list(cairo_t *cr, GList *layouts)
{
    for (GList *it = layouts; it; it = it->next) {
        Layout *layout = it->data;
        Button *btn = layout->btn;

        cairo_push_group(cr);
        paint_button(cr, layout);

        if (btn->simple) {
            g_assert_null(layout->children);
            paint_text(cr, layout);
        } else {
            g_assert_nonnull(layout->children);
            paint_button_list(cr, layout->children);
        }

        if (btn->anim != NULL && btn->anim->paint_func != NULL) {
            if (btn->anim->start == 0) {
                btn->anim->start = g_get_monotonic_time();
                log_debug("Starting animation [type=%d, start=%ld, duration=%ld, button=%p]",
                    btn->anim->type, btn->anim->start, btn->anim->duration, btn);
            }

            if (!btn->anim->paint_func(btn->anim, cr, layout))
                btn->anim->paint_func = NULL;
        }

        cairo_pop_group_to_source(cr);
        cairo_paint(cr);
    }
}

void draw_paint(Drawer *draw, Window *win)
{
    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_OVER);

    // Fill the background
    cairo_set_source_rgba(cr, draw->background.r, draw->background.g, draw->background.b, draw->background.a);
    cairo_paint(cr);

    // Treat the top-level buttons similarly to a button group
    paint_button_list(cr, draw->layouts);
    cairo_destroy(cr);

    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 void layout_set_text(Layout *layout, PangoFontDescription *desc, int height, int radius)
{
    g_assert(layout->btn->simple);

    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);
    layout->text_h = ceil(text_h);

    // 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(Drawer *draw, Window *win, GList *btns)
{
    g_list_free_full(draw->layouts, (GDestroyNotify)layout_destroy);
    draw->layouts = NULL;

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

    Button *prev = NULL;

    int x = 0;
    int radius = height / 2;
    int sep = 10;

    GList *layout_start[3] = { NULL };
    int layout_end[3] = { 0 };

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

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

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

        layout->line_w = btn->line_width;
        layout->x_pad = btn->x_pad;
        layout->y_pad = btn->y_pad;

        layout->x = x;
        layout->y = 0;

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

        if (prev == NULL || prev->align != btn->align) {
            layout_start[btn->align] = draw->layouts;
        }

        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->children = NULL;
                    child->line_w = btn->line_width;

                    child->x_pad = btn->x_pad;
                    child->y_pad = btn->y_pad;

                    child->x = x;
                    child->y = 0;

                    child->pl = pango_cairo_create_layout(window_get_context(win));
                    layout_set_text(child, draw->desc, height, radius);
                    child->width += child->line_w;

                    layout->children = g_list_prepend(layout->children, child);

                    x += child->width;
                    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)->x_pad == 0;
                bool fix_right = CAST(g_list_last(group->children)->data, Button)->x_pad == 0;

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

        if (layout->btn->simple) {
            layout->pl = pango_cairo_create_layout(window_get_context(win));
            layout_set_text(layout, draw->desc, height, radius);

            // TODO: make it work for groups
            if (btn->anim != NULL && btn->anim->layout_func != NULL) {
                if (btn->anim->start == 0) {
                    btn->anim->start = g_get_monotonic_time();
                    log_debug("Starting animation [type=%d, start=%ld, duration=%ld, button=%p]",
                        btn->anim->type, btn->anim->start, btn->anim->duration, btn);
                }

                if (!btn->anim->layout_func(btn->anim, layout))
                    btn->anim->layout_func = NULL;
            }

            layout->width += layout->line_w;
            x += layout->width;
        }

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

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

    int layout_width[3] = {
        layout_end[PANGO_ALIGN_LEFT],
        layout_end[PANGO_ALIGN_CENTER] - layout_end[PANGO_ALIGN_LEFT],
        layout_end[PANGO_ALIGN_RIGHT] - MAX(layout_end[PANGO_ALIGN_CENTER], layout_end[PANGO_ALIGN_LEFT]),
    };

    if (layout_end[PANGO_ALIGN_RIGHT] > width) {
        log_error("Layout is bigger than the window (%d vs %d)", layout_end[PANGO_ALIGN_RIGHT], width);
    }

    int center = round(width / 2);
    int center_off = center - round(layout_width[PANGO_ALIGN_CENTER] / 2) - layout_end[PANGO_ALIGN_LEFT];
    log_debug("Aligning center layout [center=%d, off=%d]", center, center_off);

    for (GList *it = layout_start[PANGO_ALIGN_CENTER]; it != NULL && it != layout_start[PANGO_ALIGN_RIGHT]; it = it->next) {
        Layout *layout = it->data;
        layout->x += center_off;
    }

    int right = width - layout_width[PANGO_ALIGN_RIGHT];
    int right_off = right - MAX(layout_end[PANGO_ALIGN_LEFT], layout_end[PANGO_ALIGN_CENTER]);
    log_debug("Aligning right layout [x=%d, off=%d]", right, right_off);

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

    log_debug("Updated layouts");
}

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

void draw_destroy(Drawer *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