#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"

#define ANIMATION(btn, which, ...) \
    do { \
        if ((btn)->anim != NULL && (btn)->anim->which##_func != NULL) { \
            if ((btn)->anim->start == 0) { \
                (btn)->anim->start = g_get_monotonic_time(); \
                log_debug("Starting animation [type=%d, func=%s, start=%ld, duration=%ld, button=%p]", \
                    (btn)->anim->type, #which, (btn)->anim->start, (btn)->anim->duration, (btn)); \
            } \
            if (!(btn)->anim->which##_func((btn)->anim, __VA_ARGS__)) \
                (btn)->anim->which##_func = NULL; \
        } \
    } while (false)

Drawer *draw_create()
{
    Drawer *draw = g_malloc0(sizeof(Drawer));
    g_assert_nonnull(draw);
    return draw;
}

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);

        // Apply before_func on the layout and cairo context
        ANIMATION(btn, before, layout, 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);
        }

        // Apply after_func on the layout and cairo context
        ANIMATION(btn, after, layout, cr);

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

void draw_paint(Drawer *draw, Window *win)
{
    // Back buffering
    cairo_surface_t *surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, draw->width, draw->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, draw->width, draw->height);

    window_paint_surface(win, surface, draw->width, draw->height);
    cairo_surface_destroy(surface);
}

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);
}

static void layout_invalidate(GList *layouts)
{
    g_list_free_full(layouts, (GDestroyNotify)layout_destroy);
}

static void layout_adjust(GList *start, GList *end, int off)
{
    // NOTE: end must be present in the list or segfault
    for (GList *it = start; it != end; it = it->next) {
        Layout *layout = it->data;
        layout->x += off;
        layout_adjust(layout->children, NULL, off);
    }
}

static void layout_set_text(Layout *layout, PangoFontDescription *desc, int height)
{
    g_assert(layout->btn->simple);
    const char *text = CAST(layout->btn, ButtonSimple)->text;

    pango_layout_set_font_description(layout->pl, desc);
    pango_layout_set_alignment(layout->pl, PANGO_ALIGN_CENTER);
    pango_layout_set_height(layout->pl, 0);
    pango_layout_set_text(layout->pl, text, -1);
    pango_layout_get_pixel_size(layout->pl, &layout->text_w, &layout->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 + height;
    layout->height = height;
}

static void compute_width(Drawer *draw, Window *win)
{
    int screen_width = win->con->screen_size->width;
    draw->width = screen_width - draw->right_pad - draw->left_pad;
    log_debug("Draw context width calculated [width=%d]", draw->width);
}

static GList *compute_group_layout(Drawer *draw, GList *btns, int bx, bool root)
{
    GList *layouts = NULL;
    for (GList *it = btns; it; it = it->next) {
        Button *btn = it->data;
        PangoAlignment align = btn->align;

        Layout *layout = g_malloc0(sizeof(Layout));
        layouts = g_list_prepend(layouts, layout);

        layout->btn = btn;
        layout->line_w = btn->line_width;
        layout->x_pad = btn->x_pad;
        layout->y_pad = btn->y_pad;
        layout->x = bx;
        layout->y = 0;

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

            // NOTE: If a group has only one children treat it as a single button
            //       As a consequence btn->align can't be trusted
            if (group->children->next == NULL) {
                layout->btn = btn = group->children->data;
                g_assert_true(btn->simple);
                goto retry;
            } else {
                layout->children = compute_group_layout(draw, group->children, bx, false);
                g_assert_nonnull(layout->children);

                Layout *last = g_list_last(layout->children)->data;
                layout->width = last->x + last->width - bx;
                layout->height = draw->height;

                // FIXME: Temporary solution to make the antialiasing (or the circles not
                //        overlapping correctly) problem less noticeable
                bool fix_left = CAST(layout->children->data, Layout)->x_pad == 0;
                if (fix_left) {
                    layout->x += 1;
                    layout->width -= 1;
                }

                bool fix_right = last->x_pad == 0;
                if (fix_right)
                    layout->width -= 1;
            }
        } else {
            layout->pl = pango_layout_new(draw->context);
            layout_set_text(layout, draw->desc, draw->height);
        }

        // NOTE: We add half a line width on both sides
        layout->width += layout->line_w;

        // Apply layout_func on the layout
        ANIMATION(btn, layout, layout);

        bx += layout->width;
        if (root) {
            draw->layout_bx[align] = bx;
            draw->layout_end[align] = layouts;
        }

        if (it->next != NULL && (!root || CAST(it->next->data, Button)->align == align))
            bx += draw->sep;
    }

    // Otherwise button_action_find will not work!
    layouts = g_list_reverse(layouts);
    return layouts;
}

void draw_compute_layout(Drawer *draw, Window *win, GList *btns)
{
    // Move this somewhere else
    compute_width(draw, win);

    memset(draw->layout_end, 0, sizeof(draw->layout_end));
    memset(draw->layout_bx, 0, sizeof(draw->layout_bx));

    g_clear_pointer(&draw->layouts, layout_invalidate);
    draw->layouts = compute_group_layout(draw, btns, 0, true);

    draw->layout_width[PANGO_ALIGN_LEFT] = draw->layout_bx[PANGO_ALIGN_LEFT];
    draw->layout_width[PANGO_ALIGN_CENTER] = draw->layout_bx[PANGO_ALIGN_CENTER] - draw->layout_bx[PANGO_ALIGN_LEFT];
    draw->layout_width[PANGO_ALIGN_RIGHT] = draw->layout_bx[PANGO_ALIGN_RIGHT] - MAX(draw->layout_bx[PANGO_ALIGN_CENTER], draw->layout_bx[PANGO_ALIGN_LEFT]);

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

    bool has_left = draw->layout_end[PANGO_ALIGN_LEFT] != NULL;
    bool has_center = draw->layout_end[PANGO_ALIGN_CENTER] != NULL;

    GList *center_start = has_left ? draw->layout_end[PANGO_ALIGN_LEFT]->next : draw->layouts;
    GList *right_start = has_center ? draw->layout_end[PANGO_ALIGN_CENTER]->next :
        has_left ? draw->layout_end[PANGO_ALIGN_LEFT]->next : draw->layouts;

    if (center_start != NULL) {
        int center = round(draw->width / 2);
        int center_off = center - draw->layout_width[PANGO_ALIGN_CENTER] / 2 - draw->layout_bx[PANGO_ALIGN_LEFT];

        log_debug("Aligning center layout [center=%d, off=%d]", center, center_off);
        layout_adjust(center_start, right_start, center_off);
    }

    if (right_start != NULL) {
        int right = draw->width - draw->layout_width[PANGO_ALIGN_RIGHT];
        int right_off = right - MAX(draw->layout_bx[PANGO_ALIGN_LEFT], draw->layout_bx[PANGO_ALIGN_CENTER]);

        log_debug("Aligning right layout [x=%d, off=%d]", right, right_off);
        layout_adjust(right_start, NULL, right_off);
    }

    log_debug("Updated layouts");
}

void draw_compute_text_size(Drawer *draw, const char *text, int *text_w, int *text_h)
{
    PangoLayout *pl = pango_layout_new(draw->context);
    pango_layout_set_font_description(pl, draw->desc);
    pango_layout_set_height(pl, 0);
    pango_layout_set_alignment(pl, PANGO_ALIGN_CENTER);
    pango_layout_set_text(pl, text, -1);
    pango_layout_get_pixel_size(pl, text_w, text_h);
    g_object_unref(pl);
}

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

void draw_set_separator(Drawer *draw, int sep)
{
    g_assert(sep >= 0);
    draw->sep = sep;
}

void draw_set_font(Drawer *draw, const char *font)
{
    log_debug("Pango loading font description '%s'", font);
    draw->desc = pango_font_description_from_string(font);
    g_assert_nonnull(draw->desc);
    log_debug("Pango found matching font '%s'", pango_font_description_get_family(draw->desc));
}

// NOTE: Don't call this between layout and paint!
void draw_set_context(Drawer *draw, PangoContext *context)
{
    g_assert_nonnull(context);
    draw->context = context;
    log_debug("Pango context updated [context=%p]", context);
}

void draw_set_size(Drawer *draw, int height, int left_pad, int right_pad, int top_pad)
{
    g_assert(height > 0);

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

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

void draw_destroy(Drawer *draw)
{
    g_clear_pointer(&draw->layouts, layout_invalidate);
    pango_font_description_free(draw->desc);
    g_free(draw);
}

// vim: ts=4 sw=4 et