////////////////////////////////////////////////////////////
//~ Key types

#define UI_NilKey ((UI_Key) { 0 })
#define UI_RootKey ((UI_Key) { 0xa3deb3749ef35a7aUll })

Struct(UI_Key)
{
    u64 hash;
};

////////////////////////////////////////////////////////////
//~ Size types

Enum(UI_SizeKind)
{
    UI_SizeKind_Pixel,      /* Exact size */
    UI_SizeKind_Grow,       /* Size as percent of parent size */
    UI_SizeKind_Shrink,     /* Size of children + padding in pixels */
};

Struct(UI_Size)
{
    UI_SizeKind kind;
    f32 v;
    f32 strictness;
};

////////////////////////////////////////////////////////////
//~ Rounding types

Enum(UI_RoundKind)
{
    UI_RoundKind_Pixel, /* Exact radius */
    UI_RoundKind_Grow,  /* Radius as percent of size */
};

Struct(UI_Round)
{
    UI_RoundKind kind;
    f32 v;
};

////////////////////////////////////////////////////////////
//~ Alignment types

Enum(UI_Alignment)
{
    UI_Alignment_TopLeft,
    UI_Alignment_Top,
    UI_Alignment_TopRight,

    UI_Alignment_Left,
    UI_Alignment_Center,
    UI_Alignment_Right,

    UI_Alignment_BottomLeft,
    UI_Alignment_Bottom,
    UI_Alignment_BottomRight,
};

Enum(UI_AxisAlignment)
{
    UI_AxisAlignment_Start,
    UI_AxisAlignment_Center,
    UI_AxisAlignment_End,
};

////////////////////////////////////////////////////////////
//~ Checkpoint types

Struct(UI_Checkpoint)
{
    u64 v;
};

////////////////////////////////////////////////////////////
//~ Box flags

Enum(UI_BoxFlag)
{
    UI_BoxFlag_None                     = 0,
    UI_BoxFlag_DrawText                 = (1 << 0),
    UI_BoxFlag_Interactable             = (1 << 1),
    UI_BoxFlag_NoTextTruncation         = (1 << 2),
    UI_BoxFlag_Floating                 = (1 << 3),
    UI_BoxFlag_NoFloatingClamp          = (1 << 4),
};

////////////////////////////////////////////////////////////
//~ Style types

#define UI_StyleKindsXMacro(X)                      \
    X(Flags,                    UI_BoxFlag)         \
    X(Parent,                   UI_Key)             \
    X(Tag,                      u64)                \
    X(ChildLayoutAxis,          Axis)               \
    X(ChildAlignmentX,          UI_AxisAlignment)   \
    X(ChildAlignmentY,          UI_AxisAlignment)   \
    X(Width,                    UI_Size)            \
    X(Height,                   UI_Size)            \
    X(BackgroundColor,          Vec4)               \
    X(BorderColor,              Vec4)               \
    X(DebugColor,               Vec4)               \
    X(Tint,                     Vec4)               \
    X(Border,                   f32)                \
    X(FloatingPos,              Vec2)               \
    X(Rounding,                 UI_Round)           \
    X(Font,                     ResourceKey)        \
    X(FontSize,                 u32)                \
    X(Text,                     String)             \
    X(BackgroundTexture,        GPU_Resource *)     \
    X(BackgroundTextureUv0,     Vec2)               \
    X(BackgroundTextureUv1,     Vec2)               \
    /*  --------------------------------------- */  \
    /*   ----------- Virtual styles ----------- */  \
    /*  --------------------------------------- */  \
    X(BeginVirtualStyles_,  i8)                     \
    X(ChildAlignment,       UI_Alignment)           \
    X(AxisSize,             UI_Size)                \
/*  -------------------------------------------------- */

Enum(UI_StyleKind)
{
    #define X(name, type) UI_StyleKind_##name,
        UI_StyleKind_None,
        UI_StyleKindsXMacro(X)
        UI_StyleKind_Count,
    #undef X
};

Struct(UI_Style)
{
    UI_StyleKind kind;
    /* Union of all style fields */
    union
    {
        #define X(name, type) type name;
            UI_StyleKindsXMacro(X)
        #undef X
    };
};

Struct(UI_StyleDesc)
{
    Axis axis;
    UI_Style style;

    /* Push */
    b32 pop_when_used;
    b32 override;

    /* Pop */
    b32 force_pop;
    b32 use;
};

Struct(UI_StyleNode)
{
    UI_StyleNode *next;
    UI_Style style;
    UI_Checkpoint checkpoint;
    b32 pop_when_used;
    b32 override;
};

Struct(UI_Stack)
{
    UI_StyleNode *style_tops[UI_StyleKind_Count];
    UI_Checkpoint top_checkpoint;
};

////////////////////////////////////////////////////////////
//~ Report types

Struct(UI_Report)
{
    b32 m1_held;

    f32 hovered;
    f32 hot;
    f32 active;

    i32 m1_downs;
    i32 m1_ups;
    i32 m1_presses;
    Vec2 last_m1_offset;

    /* Where was this box last rendered in screen coordinates */
    Vec2 screen_p0;
    Vec2 screen_p1;
};

////////////////////////////////////////////////////////////
//~ Command types

Enum(UI_CmdKind)
{
    UI_CmdKind_None,
    UI_CmdKind_BuildBox,
    UI_CmdKind_SetRawTexture,
};

Struct(UI_BoxDesc)
{
    UI_BoxFlag flags;

    UI_Key key;
    UI_Key parent;

    UI_Size pref_size[Axis_CountXY];
    UI_Round rounding;
    Vec4 background_color;
    Vec4 border_color;
    Vec4 debug_color;
    Vec4 tint;
    f32 border;
    Vec2 floating_pos;
    String text;
    ResourceKey font_resource;
    f32 font_size;
    Axis child_layout_axis;
    UI_AxisAlignment child_alignment[Axis_CountXY];
};

Struct(UI_Cmd)
{
    UI_CmdKind kind;
    union
    {
        UI_BoxDesc box;
        struct
        {
            UI_Key key;
            GPU_Resource *texture;
            Vec2 uv0;
            Vec2 uv1;
        } set_raw_texture;
    };
};

Struct(UI_CmdNode)
{
    UI_CmdNode *next;
    UI_Cmd cmd;
};

////////////////////////////////////////////////////////////
//~ Box types

Struct(UI_Box)
{
    UI_Key key;

    //- Persistent data
    UI_Box *next_in_bin;
    UI_Box *prev_in_bin;
    UI_Report report;
    u64 last_updated_tick;

    //- Tree links
    UI_Box *parent;
    UI_Box *first;
    UI_Box *last;
    UI_Box *next;
    UI_Box *prev;
    u64 count;

    //- Cmd data
    UI_BoxDesc desc;
    GPU_Resource *raw_texture;
    Vec2 raw_texture_uv0;
    Vec2 raw_texture_uv1;

    //- Pre-layout data
    u64 pre_index;
    u64 post_index;

    //- Layout data
    F_Run glyph_run;
    F_Font *font;
    f32 layout_cursor;
    f32 solved_dims[Axis_CountXY];
    f32 final_children_size_accum[Axis_CountXY];

    //- Layout results
    Vec2 p0;
    Vec2 p1;
    f32 rounding_tl;
    f32 rounding_tr;
    f32 rounding_br;
    f32 rounding_bl;
};

Struct(UI_BoxBin)
{
    UI_Box *first;
    UI_Box *last;
};

////////////////////////////////////////////////////////////
//~ Frame types

Enum(UI_FrameFlag)
{
    UI_FrameFlag_None  = 0,
    UI_FrameFlag_Debug = (1 << 0),
    UI_FrameFlag_Vsync = (1 << 1),
};

Struct(UI_Frame)
{
    WND_Frame window_frame;
    Vec2 cursor_pos;
    UI_Key hovered_box;
    UI_Key active_box;
};

////////////////////////////////////////////////////////////
//~ State types

#define UI_NumBoxLookupBins 16384

Struct(UI_BFrameState);
Struct(UI_EFrameState);

Struct(UI_State)
{
    //////////////////////////////
    //- Persistent sate

    Arena *box_arena;
    UI_BoxBin *box_bins;
    u64 boxes_count;
    UI_Box *first_free_box;

    //////////////////////////////
    //- Frame-begin state

    struct UI_BFrameState
    {
        Arena *cmds_arena;
        WND_Frame window_frame;

        u64 transient_key_seed;

        /* Time */
        u64 tick;
        i64 time_ns;
        i64 dt_ns;

        /* Control */
        Vec2 cursor_pos;
        UI_Key hovered_box;
        UI_Key active_box;

        /* Cmds */
        Vec4 swapchain_color;
        UI_FrameFlag frame_flags;
        UI_CmdNode *first_cmd_node;
        UI_CmdNode *last_cmd_node;
        u64 cmds_count;

        /* Style stack */
        UI_Stack *top_stack;
        UI_StyleNode *first_free_style_node;
    } bframe;

    //////////////////////////////
    //- Frame-end state

    struct UI_EFrameState
    {
        Arena *layout_arena;
        Arena *rects_arena;
        u64 tick;

        /* Render */
        GPU_Resource *draw_target;
        GPU_Swapchain *swapchain;
        i64 gpu_submit_fence_target;
        GPU_TransientBuffer draw_rects_tbuff;

        /* Layout */
        UI_Box *root_box;
        UI_Box **boxes_pre;
        UI_Box **boxes_post;
    } eframe;
} extern UI_state;

////////////////////////////////////////////////////////////
//~ Startup

void UI_Startup(void);

////////////////////////////////////////////////////////////
//~ Font helpers

ResourceKey UI_GetDefaultFontResource(void);

////////////////////////////////////////////////////////////
//~ Key helpers

UI_Key UI_KeyFromString(String str);
UI_Key UI_KeyF_(String fmt, ...);
#define UI_KeyF(fmt_cstr, ...) UI_KeyF_(StringFromCstrNoLimit(fmt_cstr), __VA_ARGS__, FmtEnd)

UI_Key UI_TransKey(void);

UI_Box *UI_BoxFromKey(UI_Key key);

////////////////////////////////////////////////////////////
//~ String helpers

String UI_StringF_(String fmt, ...);
#define UI_StringF(fmt_cstr, ...) UI_StringF_(StringFromCstrNoLimit(fmt_cstr), __VA_ARGS__, FmtEnd)

////////////////////////////////////////////////////////////
//~ Checkpoint helpers

UI_Checkpoint UI_PushCP(UI_Key parent);
void UI_PopCP(UI_Checkpoint pop_to);

UI_Checkpoint UI_TopCP(void);

////////////////////////////////////////////////////////////
//~ Style stack helpers

void UI_PushDefaults(void);

void     UI_PushStyle(UI_StyleDesc desc);
UI_Style UI_PopStyle(UI_StyleDesc desc);

#define UI_STYLEDESC(name, ...) (UI_StyleDesc) { .style.kind = UI_StyleKind_##name, __VA_ARGS__ }

#define UI_SetNext(name, ...)       UI_PushStyle(UI_STYLEDESC(name, .pop_when_used = 1, .style.name = __VA_ARGS__))
#define UI_Push(name, ...)          UI_PushStyle(UI_STYLEDESC(name, .style.name = __VA_ARGS__))
#define UI_ForceNext(name, ...)     UI_PushStyle(UI_STYLEDESC(name, .pop_when_used = 1, .override = 1, .style.name = __VA_ARGS__))
#define UI_ForcePush(name, ...)     UI_PushStyle(UI_STYLEDESC(name, .override = 1, .style.name = __VA_ARGS__))
#define UI_Pop(name, ...)                UI_PopStyle(UI_STYLEDESC(name, .force_pop = 1, __VA_ARGS__)).name
#define UI_PeekTop(name, ...)            UI_PopStyle(UI_STYLEDESC(name, __VA_ARGS__)).name
#define UI_UseTop(name, ...)             UI_PopStyle(UI_STYLEDESC(name, .use = 1, __VA_ARGS__)).name

#define UI_PushCopy(name, src, ...) do {   \
    UI_StyleDesc _new = src;               \
    _new.style.kind = UI_StyleKind_##name; \
    _new.style.name = __VA_ARGS__;         \
    UI_PushStyle(_new);                    \
} while (0)

////////////////////////////////////////////////////////////
//~ Size helpers

#define UI_SIZE(_kind, _v, _s) (UI_Size) { .kind = (_kind), .v = (_v), .strictness = (_s) }

#define UI_PIX(_v, _s)      UI_SIZE(UI_SizeKind_Pixel,     (_v), (_s))
#define UI_SHRINK(_v, _s)   UI_SIZE(UI_SizeKind_Shrink,    (_v), (_s))
#define UI_GROW(_v, _s)     UI_SIZE(UI_SizeKind_Grow,      (_v), (_s))
#define UI_FNT(_v, _s)      UI_SIZE(UI_SizeKind_Pixel,     (f32)UI_PeekTop(FontSize) * (_v), (_s))

////////////////////////////////////////////////////////////
//~ Rounding helpers

#define UI_ROUND(_kind, _v) (UI_Round) { .kind = (_kind), .v = (_v)}

#define UI_RPIX(_v)     UI_ROUND(UI_RoundKind_Pixel, (_v))
#define UI_RGROW(_v)    UI_ROUND(UI_RoundKind_Grow, (_v))

////////////////////////////////////////////////////////////
//~ Command helpers

UI_Key UI_BuildBoxEx(UI_Key key);
#define UI_BuildBox() UI_BuildBoxEx(UI_TransKey())

void UI_SetRawTexture(UI_Key key, GPU_Resource *texture, Vec2 uv0, Vec2 uv1);

////////////////////////////////////////////////////////////
//~ Report

UI_Report UI_ReportFromKey(UI_Key key);

////////////////////////////////////////////////////////////
//~ Begin frame

UI_Frame UI_BeginFrame(UI_FrameFlag frame_flags, Vec4 swapchain_color);

////////////////////////////////////////////////////////////
//~ Frame helpers

Arena *UI_FrameArena(void);
Vec2 UI_CursorPos(void);

////////////////////////////////////////////////////////////
//~ End frame

i64 UI_EndFrame(UI_Frame frame);