#ifndef YASL_BACKEND_H
#define YASL_BACKEND_H

#include "yasl/yasl.h"
#include "yasl/loop.h"
#include "yasl/native.h"
#include "common/input.h"
#include "common/timing.h"

struct yasl_backend_ops;

struct yasl_display {
    const struct yasl_backend_ops *ops;
    void *native_handle;
    struct yasl_display_cbs callbacks;
    struct yasl_loop *loop;
    void *app_runner;
};

struct yasl_surface {
    struct yasl_display *display;
    void *native_handle;
    struct yasl_vector2i size;
    uint32_t scale_120;
    uint32_t state; /* Authoritative YASL_STATE_* bitmask, maintained by the backend. */
    uint32_t bg_color;
    struct yasl_window_cbs callbacks;
    void *ud;
    uint64_t frame_generation;
    struct input_queue input;
    enum yasl_pointer_mode pointer_mode;
    struct yasl_frame_clock clock;
    uint64_t frames_skipped;
    yasl_timer_id *timers;
    int timer_count;
    int timer_capacity;
    void *app_surface;
};

void yasl_surface_clear_timers(struct yasl_surface *s);
struct yasl_surface *yasl_create_toplevel(struct yasl_display *d,
        const struct yasl_window_spec *spec, void *graphics_device);

static inline uint64_t yasl_frame_begin(struct yasl_surface *s)
{
    if (++s->frame_generation == 0) ++s->frame_generation;
    return s->frame_generation;
}

struct yasl_backend_ops {
    enum yasl_backend type;
    struct yasl_display *(*display_open)(struct yasl_loop *loop, const struct yasl_display_spec *spec);
    void (*display_close)(struct yasl_display *d);
    uint32_t (*display_caps)(const struct yasl_display *d);
    int (*display_dispatch_timeout)(struct yasl_display *d, int timeout_ms);
    void (*display_flush)(struct yasl_display *d);
    int (*display_modifiers)(const struct yasl_display *d);
    void (*display_copy)(struct yasl_display *d, enum yasl_selection sel, const char *text);
    void (*display_paste)(struct yasl_display *d, enum yasl_selection sel, struct yasl_surface *target);
    bool (*display_drag_start)(struct yasl_display *d, struct yasl_surface *origin, const struct yasl_drag_image *image, const struct yasl_drag_listener *l, void *ud);
    void (*display_drag_cancel)(struct yasl_display *d);
    /* Create with callbacks disabled; common code installs them after return. */
    struct yasl_surface *(*surface_create_toplevel)(struct yasl_display *d,
            const struct yasl_window_spec *spec, void *graphics_device);
    struct yasl_surface *(*surface_create_popup)(struct yasl_surface *parent, const struct yasl_popup_spec *spec);
    bool (*surface_popup_reposition)(struct yasl_surface *popup, const struct yasl_popup_spec *spec);
    void (*surface_destroy)(struct yasl_surface *s);
    struct yasl_display *(*surface_display)(const struct yasl_surface *s);
    /* Copy only; must not invoke application callbacks. */
    void (*surface_set_callbacks)(struct yasl_surface *s, const struct yasl_window_cbs *cbs, void *ud);
    void (*surface_set_title)(struct yasl_surface *s, const char *title);
    void (*surface_schedule_redraw)(struct yasl_surface *s);
    bool (*surface_present)(struct yasl_surface *s, const struct yasl_framebuffer *fb, const struct yasl_damage_list *damage);
    /* Optional; NULL means the common input queue is drained. */
    bool (*surface_poll_event)(struct yasl_surface *s, struct yasl_event *ev);
    /* Optional; NULL means only YASL_POINTER_NORMAL is supported. Backends that
     * implement RELATIVE push POINTER_MOTION with delta set and pos frozen. */
    bool (*surface_set_pointer_mode)(struct yasl_surface *s, enum yasl_pointer_mode mode);
    struct yasl_geometry (*surface_geometry)(const struct yasl_surface *s);
    struct yasl_timing (*surface_timing)(const struct yasl_surface *s);
    uint64_t (*surface_frame_time_ns)(struct yasl_surface *s, uint64_t now);
    void (*surface_set_cursor)(struct yasl_surface *s, enum yasl_cursor cursor);
    void (*surface_set_background_color)(struct yasl_surface *s, uint32_t bg);
    const char *(*surface_ime_preedit)(const struct yasl_surface *s);
    bool (*surface_ime_preedit_cursor)(const struct yasl_surface *s, int *begin, int *end);
    void (*surface_set_ime_caret)(struct yasl_surface *s, struct yasl_rect2i caret);
    bool (*surface_start_interactive_move)(struct yasl_surface *s);
    bool (*surface_start_interactive_resize)(struct yasl_surface *s, enum yasl_resize_edge edge);
    bool (*surface_show_window_menu)(struct yasl_surface *s, struct yasl_vector2i pos);
    bool (*surface_drag_carry)(struct yasl_surface *s, struct yasl_vector2i offset);
    bool (*surface_place_under_pointer)(struct yasl_surface *s, struct yasl_vector2i at);
    void *(*display_get_native_handle)(struct yasl_display *d);
    void *(*surface_get_native_handle)(struct yasl_surface *s);
    bool (*surface_get_native_frame)(struct yasl_surface *s,
            const struct yasl_framebuffer *target, struct yasl_native_frame *out);
};

#if YASL_HAS_WAYLAND
extern const struct yasl_backend_ops yasl_wayland_backend;
#endif
#if YASL_HAS_X11
extern const struct yasl_backend_ops yasl_x11_backend;
#endif
#if YASL_HAS_COCOA
extern const struct yasl_backend_ops yasl_cocoa_backend;
#endif

#endif