#include <glib.h>
#include <math.h>
#include <cairo.h>
#include <cairo-xcb.h>
#include <xcb/xcb.h>
#include <xcb/xcb_aux.h>
#include <xcb/xproto.h>
#include <xcb/xcb_icccm.h>
#include <xcb/xcb_xrm.h>
#include <xcb/randr.h>
#include <xcb/xcb_atom.h>
#include <xcb/xcb_event.h>

#include "x11.h"
#include "log.h"

// TODO: Event logic should be decoupled from Window logic
#include "draw.h"

struct Window {
    xcb_screen_t *screen;
    xcb_connection_t *connection;
    xcb_xrm_database_t *database;
    xcb_drawable_t window;
    xcb_visualtype_t *visual_type;
    cairo_surface_t *surface;
    cairo_t *cr;
    double dpi;
    uint16_t screen_width;
    uint16_t screen_height;
    int x, y;
    int width, height;
    GSource *source;
};

typedef struct {
    GSource source;
    Window *win;
    xcb_generic_event_t *event;
} XcbSource;

static xcb_atom_t intern_atom(Window *win, const char *atom)
{
    // TODO: Error handling
    xcb_intern_atom_cookie_t cookie = xcb_intern_atom(win->connection, false, strlen(atom), atom);
    return xcb_intern_atom_reply(win->connection, cookie, NULL)->atom;
}

static gboolean xcb_source_check(GSource *source)
{
    XcbSource *xsource = (XcbSource *)source;
    g_assert_null(xsource->event);
    xsource->event = xcb_poll_for_event(xsource->win->connection);
    return xsource->event != NULL;
}

static gboolean xcb_source_dispatch(GSource *source, GSourceFunc callback, gpointer data)
{
    XcbSource *xsource = (XcbSource *)source;
    g_assert_nonnull(xsource->event);
    g_assert_nonnull(callback);
    g_assert_nonnull(data);

    do {
        switch (xsource->event->response_type & ~0x80) {
            case 0: {
                xcb_generic_error_t *error = (xcb_generic_error_t *)xsource->event;

                // TODO: This code crashes the program, so we should handle the errors
                log_warning("Xcb event loop error '%s' [type %d]",
                            xcb_event_get_error_label(error->response_type),
                            error->response_type);
                break;
            }

            case XCB_EXPOSE: {
                xcb_expose_event_t *expose = (xcb_expose_event_t *)xsource->event;
                log_debug("Processing event 'Expose' [type %d]", XCB_EXPOSE);

                // Redraw
                callback(data);
                break;
            }

            case XCB_BUTTON_PRESS: {
                log_debug("Keypress event");
                break;
            }

            default: {
                log_debug("Ignoring event '%s' [type %d]",
                          xcb_event_get_label(xsource->event->response_type),
                          XCB_EVENT_RESPONSE_TYPE(xsource->event));
            }
        }
    } while ((xsource->event = xcb_poll_for_event(xsource->win->connection)) != NULL);

    return G_SOURCE_CONTINUE;
}

static void xcb_source_finalize(GSource *source)
{
    log_debug("Xcb event loop finalized");
}

static GSourceFuncs source_fns = {
    NULL,
    xcb_source_check,
    xcb_source_dispatch,
    xcb_source_finalize,
};

static void attach_source(Window *win)
{
    XcbSource *source = (XcbSource *)g_source_new(&source_fns, sizeof(XcbSource));
    source->win = win;
    source->event = NULL;

    win->source = (GSource *)source;
    g_source_set_static_name(win->source, "XcbSource");

    // TODO: Draw should be decoupled from this file
    g_source_set_callback(win->source, G_SOURCE_FUNC(draw), win, NULL);

    g_source_add_unix_fd(win->source, xcb_get_file_descriptor(win->connection), G_IO_IN | G_IO_HUP | G_IO_ERR);
    g_source_attach(win->source, NULL);
}

Window *window_create(void)
{
    Window *win = g_malloc0(sizeof(Window));

    int preferred_screen = 0;
    win->connection = xcb_connect(NULL, &preferred_screen);
    g_assert_true(win->connection != NULL && !xcb_connection_has_error(win->connection));
    log_debug("Xcb established connection");

    xcb_screen_iterator_t iter = xcb_setup_roots_iterator(xcb_get_setup(win->connection));
    log_debug("Default screen %d", preferred_screen);

    while (preferred_screen != 0 && iter.rem) {
        xcb_screen_next(&iter);
        preferred_screen--;
    }

    win->screen = iter.data;

    xcb_randr_query_version_cookie_t version_cookie = xcb_randr_query_version(win->connection,
                                                                              XCB_RANDR_MAJOR_VERSION,
                                                                              XCB_RANDR_MINOR_VERSION);

    xcb_generic_error_t *error;
    xcb_randr_query_version_reply_t *randr_version = xcb_randr_query_version_reply(win->connection,
                                                                                   version_cookie,
                                                                                   &error);

    log_debug("RandR version %d.%d", randr_version->major_version, randr_version->minor_version);
    g_assert_true(error == NULL || randr_version->major_version < 1);

    xcb_randr_get_screen_info_cookie_t cookie = xcb_randr_get_screen_info(win->connection, win->screen->root);
    xcb_randr_get_screen_info_reply_t *info_reply = xcb_randr_get_screen_info_reply(win->connection, cookie, &error);
    g_assert_null(error);

    xcb_randr_screen_size_t *screen_size = xcb_randr_get_screen_info_sizes(info_reply);
    log_debug("Screen size [width=%d, height=%d]", screen_size->width, screen_size->height);

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

    win->width = win->height = 0;
    win->x = win->y = 0;

    xcb_randr_select_input(win->connection,
                           win->window,
                           XCB_RANDR_NOTIFY_MASK_SCREEN_CHANGE |
                           XCB_RANDR_NOTIFY_MASK_OUTPUT_CHANGE |
                           XCB_RANDR_NOTIFY_MASK_OUTPUT_PROPERTY);

    win->database = xcb_xrm_database_from_default(win->connection);
    g_assert_nonnull(win->database);

    char *dpi_value;
    if (xcb_xrm_resource_get_string(win->database, "Xft.dpi", "Xft.dpi", &dpi_value) >= 0) {
        log_debug("Xrm query '%s' found '%s'", "Xft.dpi", dpi_value);
        win->dpi = strtod(dpi_value, NULL);
        g_free(dpi_value);
    } else {
        log_debug("Xrm query '%s' not found", "Xft.dpi");
        win->dpi = 96.0;
        //win->dpi = (double)screen_size->height * 25.4 / (double)screen_size->mheight;
        log_debug("Fallback dpi value '%lf'", win->dpi);
    }
    xcb_depth_iterator_t depth_iter = xcb_screen_allowed_depths_iterator(win->screen);

    while (depth_iter.rem) {
        xcb_visualtype_iterator_t visual_iter = xcb_depth_visuals_iterator(depth_iter.data);

        while (visual_iter.rem) {
            if (win->screen->root_visual == visual_iter.data->visual_id) {
                win->visual_type = visual_iter.data;
                goto found_visual;
            }
            xcb_visualtype_next(&visual_iter);
        }
        xcb_depth_next(&depth_iter);
    }

found_visual:

    log_debug("Xcb visual type found (id %u)", win->visual_type->visual_id);

    const uint32_t value_mask = XCB_CW_BACK_PIXMAP | XCB_CW_BACK_PIXEL | XCB_CW_BORDER_PIXEL
                              | XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK | XCB_CW_COLORMAP;

    const uint32_t event_mask = XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_STRUCTURE_NOTIFY
                              | XCB_EVENT_MASK_KEY_PRESS | XCB_EVENT_MASK_FOCUS_CHANGE
                              | XCB_EVENT_MASK_BUTTON_RELEASE | XCB_EVENT_MASK_BUTTON_PRESS;

    xcb_colormap_t colormap = xcb_generate_id(win->connection);
	xcb_create_colormap(win->connection, XCB_COLORMAP_ALLOC_NONE, colormap, win->screen->root, win->visual_type->visual_id);

    log_debug("Xcb colormap created (id %u)", colormap);

    const uint32_t value_list[] = {
        XCB_NONE,   // back pixmap
        0x000000,   // back pixel
        0x000000,   // border pixel
        true,       // override redirect
        event_mask, // event mask
        colormap    // colormap
    };

    win->width = win->height = 1;
    log_debug("Window temporary size [width=%d, height=%d]", win->width, win->height);

    win->x = win->y = 0;
    log_debug("Window temporary position [x=%d, y=%d]", win->x, win->y);

    win->window = xcb_generate_id(win->connection);
    xcb_create_window(win->connection,
                      XCB_COPY_FROM_PARENT,
                      win->window, win->screen->root,
                      win->x, win->y,
                      win->width, win->height,
                      0, // border
                      XCB_WINDOW_CLASS_INPUT_OUTPUT,
                      win->screen->root_visual,
                      value_mask,
                      value_list);

    log_debug("Xcb window created (id %u)", win->window);

    xcb_icccm_set_wm_name(win->connection, win->window, XCB_ATOM_STRING, 8, strlen("comet"), "comet");
    xcb_map_window(win->connection, win->window);

    //xcb_atom_t NET_WM_WINDOW_OPACITY = intern_atom(win, "_NET_WM_WINDOW_OPACITY");
    //xcb_atom_t CARDINAL = intern_atom(win, "CARDINAL");

    // Value between 0 and 1
    //double transparency = 0.8;
    //unsigned long opacity = 0xffffffff * transparency;

    //error =
    //xcb_request_check(win->connection,
    //xcb_change_property_checked(win->connection,
    //                    XCB_PROP_MODE_REPLACE,
    //                    win->window,
    //                    NET_WM_WINDOW_OPACITY,
    //                    CARDINAL,
    //                    32,
    //                    1,
    //                    (char *)&opacity));
    //assert(error == NULL);
    //log_debug("Window '%s' set to '%d%%'", "opacity", (int)round(100 - 100 * transparency));

    xcb_flush(win->connection);
    log_debug("Xcb initialized");

    win->surface = cairo_xcb_surface_create(win->connection,
                                            win->window,
                                            win->visual_type,
                                            screen_size->width,
                                            screen_size->height);

    g_assert_cmpint(cairo_surface_status(win->surface), ==, CAIRO_STATUS_SUCCESS);

    win->cr = cairo_create(win->surface);
    g_assert_cmpint(cairo_status(win->cr), ==, CAIRO_STATUS_SUCCESS);

    log_debug("Cairo initialized");

    attach_source(win);
    log_debug("Xcb event loop attached");

    return win;
}

cairo_t *window_get_context(Window *win)
{
    return win->cr;
}

double window_get_scale(Window *win)
{
    return MAX(1, win->dpi/96.);
}

void window_get_screen_size(Window *win, int *width, int *height)
{
    *width = win->screen_width;
    *height = win->screen_height;
}

void window_move(Window *win, int x, int y)
{
    if (win->x == x && win->y == y) return;

    win->x = x;
    win->y = y;

    const uint32_t values[] = { x, y };
    xcb_configure_window(win->connection,
                         win->window,
                         XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y,
                         values);

    log_debug("Window updated position [x=%d, y=%d]", win->x, win->y);
}

void window_resize(Window *win, int width, int height)
{
    if (win->width == width && win->height == height) return;

    win->width  = width;
    win->height = height;

    const uint32_t values[] = { width, height };
    xcb_configure_window(win->connection,
                         win->window,
                         XCB_CONFIG_WINDOW_WIDTH | XCB_CONFIG_WINDOW_HEIGHT,
                         values);

    log_debug("Window updated size [width=%d, height=%d]", win->width, win->height);
}

void window_paint_surface(Window *win, cairo_surface_t *surface, int width, int height)
{
    cairo_xcb_surface_set_size(win->surface, width, height);
    xcb_clear_area(win->connection, false, win->window, 0, 0, 0, 0);

    cairo_set_source_surface(win->cr, surface, 0, 0);
    cairo_paint(win->cr);
    cairo_show_page(win->cr);

    xcb_flush(win->connection);
}

void window_destroy(Window *win)
{
    g_source_destroy(win->source);
    g_source_unref(win->source);

    cairo_destroy(win->cr);
    cairo_surface_destroy(win->surface);

    xcb_xrm_database_free(win->database);
    xcb_disconnect(win->connection);
    g_free(win);
}

// vim: ts=4 sw=4 et