#include <glib.h>
#include <unistd.h>
#include <math.h>
#include <cairo.h>
#include <cairo-xcb.h>
#include <xcb/xcb.h>
#include <xcb/xproto.h>
#include <xcb/xcb_aux.h>
#include <xcb/xcb_icccm.h>
#include <xcb/xcb_ewmh.h>
#include <xcb/xcb_xrm.h>
#include <xcb/xcb_errors.h>
#include <xcb/randr.h>
#include <xcb/shape.h>

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

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

struct Window {
    xcb_connection_t *connection;
    xcb_screen_t *screen;
    xcb_randr_screen_size_t *screen_size;
    xcb_xrm_database_t *database;
    xcb_errors_context_t *errors;
    xcb_drawable_t window;
    xcb_visualtype_t *visual_type;
    xcb_ewmh_connection_t ewmh;
    cairo_surface_t *surface;
    cairo_t *cr;
    double dpi;
    int x, y;
    int width, height;
    GSource *source;
};

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

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);

    Window *win = (Window *)data;

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

                const char *extension;
                const char *name  = xcb_errors_get_name_for_error(win->errors, error->error_code, &extension);
                const char *major = xcb_errors_get_name_for_major_code(win->errors, error->major_code);
                const char *minor = xcb_errors_get_name_for_minor_code(win->errors, error->major_code, error->minor_code);

                // TODO: Handle errors instead of aborting
                log_error("Xcb error '%s' [extension=%s, major=%s, minor=%s, resource=%u, sequence=%u]",
                          name,
                          extension ? extension : "none",
                          major,
                          minor ? minor : "none",
                          (unsigned int)error->resource_id,
                          (unsigned int)error->sequence);
                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_RELEASE: {
                log_debug("Mouse event");
                break;
            }

            case XCB_PROPERTY_NOTIFY: {
                xcb_property_notify_event_t *property = (xcb_property_notify_event_t *)xsource->event;
                log_debug("Processing event 'PropertyNotify' [type=%d]", XCB_PROPERTY_NOTIFY);

                if (property->atom == XCB_ATOM_RESOURCE_MANAGER) {
                    window_update_scale(data);

                    // Redraw
                    callback(data);
                }
                break;
            }

            default: {
                const char *extension;
                const char *name = xcb_errors_get_name_for_xcb_event(win->errors, xsource->event, &extension);

                log_debug("Ignoring event '%s' [extension=%s, type=%d]",
                          name,
                          extension ? extension : "none",
                          xsource->event->response_type & 0x7f);
            }
        }
    } 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);
}

static bool query_xrm(Window *win, const char *res, char **value)
{
    if (xcb_xrm_resource_get_string(win->database,res, res, value) >= 0) {
        log_debug("Xrm query '%s' found '%s'", res, *value);
        return true;
    }

    log_debug("Xrm query '%s' not found", res);
    return false;
}

static xcb_atom_t intern_atom(Window *win, const char *atom)
{
    xcb_generic_error_t *error;
    xcb_intern_atom_cookie_t cookie = xcb_intern_atom(win->connection, false, strlen(atom), atom);
    xcb_intern_atom_reply_t *reply = xcb_intern_atom_reply(win->connection, cookie, &error);

    g_assert_null(error);
    xcb_atom_t id = reply->atom;
    g_free(reply);
    return id;
}

static void wm_set_size(Window *win)
{
    xcb_size_hints_t hints;
    xcb_icccm_size_hints_set_size(&hints, false, win->width, win->height);
    xcb_icccm_size_hints_set_min_size(&hints, win->width, win->height);
    xcb_icccm_size_hints_set_max_size(&hints, win->width, win->height);
    xcb_icccm_size_hints_set_base_size(&hints, win->width, win->height);
    xcb_icccm_size_hints_set_position(&hints, false, win->x, win->y);

    xcb_icccm_set_wm_size_hints(win->connection, win->window, XCB_ATOM_WM_NORMAL_HINTS, &hints);
    log_debug("Xcb icccm updated size hints");
}

static void wm_set_struts(Window *win)
{
    const uint32_t end = MAX(0, win->x + win->width - 1);

    const uint32_t values[12] = {
        0,      0,   win->height, 0,   // left, right, top, bottom
        0,      0,   0,           0,   // left y0, left y1, right y0, right y1
        win->x, end, 0,           0,   // top y0, top y1, bottom y0, bottom y1
    };

    xcb_change_property(win->connection,
                        XCB_PROP_MODE_REPLACE,
                        win->window,
                        win->ewmh._NET_WM_STRUT,
                        XCB_ATOM_CARDINAL,
                        32,
                        4,
                        values);

    xcb_change_property(win->connection,
                        XCB_PROP_MODE_REPLACE,
                        win->window,
                        win->ewmh._NET_WM_STRUT_PARTIAL,
                        XCB_ATOM_CARDINAL,
                        32,
                        12,
                        values);

    log_debug("Xcb ewmh struts updated");
}

static void wm_setup(Window *win)
{
    const char *title = "comet";
    xcb_icccm_set_wm_name(win->connection, win->window, XCB_ATOM_STRING, 8, strlen(title), title);
    log_debug("Window updated title [%s]", title);

    const char class[] = "comet\0Comet";
    xcb_icccm_set_wm_class(win->connection, win->window, strlen(class), class);
    log_debug("Window updated class [%s]", "comet\\0Comet");

    xcb_generic_error_t *error;
    xcb_intern_atom_cookie_t *ewmh_cookie = xcb_ewmh_init_atoms(win->connection, &win->ewmh);

    g_assert_true(xcb_ewmh_init_atoms_replies(&win->ewmh, ewmh_cookie, &error));
    g_assert_null(error);
    log_debug("Xcb ewmh connected");

    xcb_ewmh_set_wm_window_type(&win->ewmh, win->window, 1, &win->ewmh._NET_WM_WINDOW_TYPE_DOCK);

    xcb_atom_t state[] = {
        win->ewmh._NET_WM_STATE_STICKY,
        win->ewmh._NET_WM_STATE_ABOVE
    };
    xcb_ewmh_set_wm_state(&win->ewmh, win->window, G_N_ELEMENTS(state), state);

    xcb_ewmh_set_wm_desktop(&win->ewmh, win->window, 0xFFFFFFFF);

    xcb_ewmh_set_wm_pid(&win->ewmh, win->window, getpid());

    wm_set_size(win);

    wm_set_struts(win);
}

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 connected");

    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);

    g_assert_null(error);
    log_debug("RandR loaded [version=%d.%d]", randr_version->major_version, randr_version->minor_version);
    g_assert_cmpint(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);

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

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

    xcb_randr_select_input(win->connection,
                           win->screen->root,
                           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);

    window_update_scale(win);

    g_assert(xcb_errors_context_new(win->connection, &win->errors) == 0);
    log_debug("Xcb errors loaded");

    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);

    wm_setup(win);
    log_debug("Window wm options completed");

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

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

    g_assert_cmpint(cairo_surface_status(win->surface), ==, CAIRO_STATUS_SUCCESS);
    log_debug("Cairo surface created");

    win->cr = cairo_create(win->surface);
    g_assert_cmpint(cairo_status(win->cr), ==, CAIRO_STATUS_SUCCESS);
    log_debug("Cairo context created");


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

    return win;
}

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

void window_update_scale(Window *win)
{
    const char *dpi_res = "Xft.dpi";
    char *dpi_value;

    if (query_xrm(win, dpi_res, &dpi_value)) {
        win->dpi = strtod(dpi_value, NULL);
        g_free(dpi_value);
    } else {
        win->dpi = (double)win->screen_size->height * 25.4 / (double)win->screen_size->mheight;
        log_debug("Fallback dpi value '%.2lf'", win->dpi);
    }
}

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_size->width;
    *height = win->screen_size->height;
}

void window_set_opacity(Window *win, double alpha)
{
    // Value between 0 and 1
    g_assert_true(alpha >= 0 && alpha <= 1);
    unsigned long opacity = 0xffffffff * alpha;

    xcb_atom_t _NET_WM_WINDOW_OPACITY = intern_atom(win, "_NET_WM_WINDOW_OPACITY");
    xcb_change_property(win->connection,
                        XCB_PROP_MODE_REPLACE,
                        win->window,
                        _NET_WM_WINDOW_OPACITY,
                        XCB_ATOM_CARDINAL,
                        32,
                        1,
                        (char *)&opacity);

    log_debug("Window updated opacity [%.2lf%%]", alpha * 100.0);

}

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);

    wm_set_size(win);
}

static void window_paint_corners(Window *win)
{
    // TODO: Actually make this a parameter
    int radius = win->height / 2;
    double degree = M_PI / 180.0;

    // TODO: Check this value
    int depth = 1;

    xcb_pixmap_t bitmap = xcb_generate_id(win->connection);
    xcb_create_pixmap(win->connection, depth, bitmap, win->window, win->width, win->height);
    log_debug("Xcb pixmap created [id=%u]", bitmap);

    cairo_surface_t *surface = cairo_xcb_surface_create_for_bitmap(win->connection,
                                                                   win->screen,
                                                                   bitmap,
                                                                   win->width,
                                                                   win->height);

    cairo_t *cr = cairo_create(surface);

    // TODO: Fix antialiasing situation
    //cairo_set_antialias(cr, CAIRO_ANTIALIAS_GOOD);

    cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE);
    cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);

    cairo_set_source_rgba(cr, 0, 0, 0, 0);
    cairo_paint(cr);

    // TODO: Decouple somewhat drawing and X11
    cairo_set_source_rgba(cr, 1, 1, 1, 1);
    cairo_arc(cr, radius, radius, radius, 90.0 * degree, 270 * degree);
    cairo_arc(cr, win->width - radius, radius, radius, 270 * degree, 450 * degree);
    cairo_fill(cr);

    log_debug("Xcb shape painted");

    cairo_show_page(cr);
    cairo_destroy(cr);
    cairo_surface_flush(surface);
    cairo_surface_destroy(surface);

    xcb_shape_mask(win->connection, XCB_SHAPE_SO_SET, XCB_SHAPE_SK_BOUNDING, win->window, 0, 0, bitmap);
    xcb_shape_select_input(win->connection, win->window, XCB_SHAPE_NOTIFY);
    log_debug("Xcb shape mask configured");

    xcb_free_pixmap(win->connection, bitmap);
}

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);

    window_paint_corners(win);

    xcb_circulate_window(win->connection, XCB_CIRCULATE_RAISE_LOWEST, win->window);
    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_ewmh_connection_wipe(&win->ewmh);
    xcb_errors_context_free(win->errors);
    xcb_xrm_database_free(win->database);
    xcb_disconnect(win->connection);
    g_free(win);
}

// vim: ts=4 sw=4 et