#ifndef GP_H
#define GP_H

struct sys_window;

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

struct gp_startup_receipt { i32 _; };
struct gp_startup_receipt gp_startup(void);

/* ========================== *
 * Resource
 * ========================== */

struct gp_resource;

/* 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 then referenced in any flow
 * dispatches. */
void gp_resource_release(struct gp_resource *resource);

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

struct v2i32 gp_texture_get_size(struct gp_resource *texture);

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

enum gp_cmd_kind {
    GP_CMD_KIND_NONE,
    GP_CMD_KIND_DRAW_SHAPE,
    GP_CMD_KIND_DRAW_MATERIAL,
    GP_CMD_KIND_PUSH_GRID,

    NUM_GP_CMD_KINDS
};

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

struct gp_cmd_desc {
    enum gp_cmd_kind kind;
    union {
        struct {
            struct xform xf;
            struct sprite_tag sprite;
            struct gp_resource *texture;
            struct clip_rect clip;
            u32 tint;
            f32 emittance;
            i32 grid_cmd_id;
        } material;
        struct {
            struct v2_array vertices;
            struct gp_indices indices;
            u32 color;
        } shape;
        struct {
            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 gp_dispatch_params {
    struct gp_flow *flow;
    struct gp_resource *draw_target;
    struct rect draw_target_viewport;
    struct xform draw_target_view;
    b32 clear_target;
};

struct gp_flow *gp_flow_alloc(void);

/* Returns a cmd id internal to the flow */
i32 gp_push_cmd(struct gp_flow *gp_flow, struct gp_cmd_desc *desc);

void gp_dispatch(struct gp_dispatch_params params);

/* ========================== *
 * Memory info
 * ========================== */

struct gp_memory_info {
    u64 local_used;
    u64 local_budget;
    u64 non_local_used;
    u64 non_local_budget;
};

struct gp_memory_info gp_query_memory_info(void);

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

/* 1. Clears the backbuffer and ensures it's 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_resource *texture, struct xform texture_xf, i32 vsync);

#endif