#ifndef GP_H
#define GP_H

struct sys_window;
struct work_startup_receipt;

/* ========================== *
 * Startup
 * ========================== */

struct gp_startup_receipt { i32 _; };
struct gp_startup_receipt gp_startup(struct work_startup_receipt *work_sr);

/* ========================== *
 * Handle
 * ========================== */

struct gp_handle {
    union {
        /* dx11 style */
        u64 v;
        /* dx12 style */
        struct {
            u64 gen;
            u64 idx;
        };
    };
};

struct gp_handle_array {
    u64 count;
    struct gp_handle **handles;
};

/* NOTE: Internally, the layer will make sure to not release any resources
 * until after the GPU finishes using them. However, it is up to the caller
 * to make sure the released resources aren't referenced in any flows before
 * dispatching. */
void gp_release(struct gp_handle handle);

/* ========================== *
 * Texture
 * ========================== */

enum gp_texture_format {
    GP_TEXTURE_FORMAT_NONE,
    GP_TEXTURE_FORMAT_R8G8B8A8_UNORM,
    GP_TEXTURE_FORMAT_R8G8B8A8_UNORM_SRGB,

    NUM_GP_TEXTURE_FORMATS
};

enum gp_texture_flag {
    GP_TEXTURE_FLAG_NONE           = (0),
    GP_TEXTURE_FLAG_TARGETABLE     = (1 << 0)
};

struct gp_handle gp_texture_alloc(enum gp_texture_format format, u32 flags, struct v2i32 size, void *initial_data);

void gp_texture_clear(struct gp_handle target_texture, u32 clear_color);

struct v2i32 gp_texture_get_size(struct gp_handle texture);

/* ========================== *
 * Flow
 * ========================== */

struct gp_indices {
    u32 count;
    u32 *indices;
};

enum gp_cmd_kind {
    GP_CMD_KIND_NONE,
    GP_CMD_KIND_DRAW_MESH,
    GP_CMD_KIND_DRAW_TEXTURE,
    GP_CMD_KIND_DRAW_GRID,
    GP_CMD_KIND_TEST,

    NUM_GP_CMD_KINDS
};

struct gp_cmd_params {
    enum gp_cmd_kind kind;
    union {
        struct {
            struct v2_array vertices;
            struct gp_indices indices;
            u32 color;
        } mesh;
        struct {
            struct xform xf;
            struct sprite_tag sprite;
            struct gp_handle texture;
            struct clip_rect clip;
            u32 tint;
            f32 emittance;
        } texture;
        struct {
            struct xform xf;
            f32 line_thickness;
            f32 line_spacing;
            struct v2 offset;
            u32 bg0_color;
            u32 bg1_color;
            u32 line_color;
            u32 x_color;
            u32 y_color;
        } grid;
        struct {
            struct xform xf;
        } test;
    };
};

struct gp_dispatch_params {
    struct gp_handle flow;
    struct gp_handle draw_target;
    struct rect draw_target_viewport;
    struct xform draw_target_view;
    b32 clear_target;
};

struct gp_handle gp_flow_alloc(void);

void gp_push_cmd(struct gp_handle gp_flow, struct gp_cmd_params params);

void gp_dispatch(struct gp_dispatch_params params);

/* ========================== *
 * Present
 * ========================== */

/* 1. Clears the backbuffer and ensures its at size `backbuffer_resolution`
 * 2. Blits `texture` to the backbuffer using `texture_xf` (applied to centered unit square)
 * 3. Presents the backbuffer */
void gp_present(struct sys_window *window, struct v2i32 backbuffer_resolution, struct gp_handle texture, struct xform texture_xf, i32 vsync);

#endif