typedef void ui_custom_draw_t(struct ui_box_t *box);

typedef struct ui_code_loc_t ui_code_loc_t;
struct ui_code_loc_t {
    char *file;
    int line;
    int counter;
};

typedef struct ui_id_t ui_id_t;
struct ui_id_t {
    u64 value;
};

typedef struct ui_box_flags_t ui_box_flags_t;
struct ui_box_flags_t {
    b8 draw_rect: 1;
    b8 draw_border: 1;
    b8 draw_text: 1;

    b8 clip_rect : 1;
};

typedef enum {
    ui_text_align_left,
    ui_text_align_center,
} ui_text_align_t;

typedef enum {
    ui_axis2_invalid = -1,
    ui_axis2_x,
    ui_axis2_y,
    ui_axis2_count,
} ui_axis2_t;

typedef enum {
    ui_lop_cut_top,
    ui_lop_cut_bottom,
    ui_lop_cut_left,
    ui_lop_cut_right,
    ui_lop_idle,
} ui_lop_t;

#include "ui.gen.h"

typedef struct ui_caret_t ui_caret_t;
struct ui_caret_t {
    union {
        i32 e[2];
        struct { r1i32_t range; };
    };
    i32 ifront;
};

fn ui_caret_t ui_caret_clamp(ui_caret_t c, i32 min, i32 max) {
    return (ui_caret_t){CLAMP(c.e[0],min,max), CLAMP(c.e[1],min,max), c.ifront};
}
fn i32 ui_caret_front(ui_caret_t c) { return c.e[c.ifront]; }
fn i32 ui_caret_back(ui_caret_t c) { return c.e[c.ifront ? 0 : 1]; }

ui_caret_t ui_caret(i32 front, i32 back) {
    ui_caret_t result = {0};
    if (front >= back) {
        result.range.min = back;
        result.range.max = front;
        result.ifront = 1;
    } else {
        result.range.min = front;
        result.range.max = back;
        result.ifront = 0;
    }
    return result;
}

ui_caret_t ui_caret_set_back(ui_caret_t caret, i32 back) {
    i32 front = ui_caret_front(caret);
    ui_caret_t result = ui_caret(front, back);
    return result;
}

ui_caret_t ui_caret_set_front(ui_caret_t caret, i32 front) {
    i32 back = ui_caret_back(caret);
    ui_caret_t result = ui_caret(front, back);
    return result;
}

fn ui_caret_t ui_carets(i32 x) {
    return ui_caret(x, x);
}

typedef struct ui_text_input_t ui_text_input_t;
struct ui_text_input_t {
    union {
        struct { char *str; i64 len; };
        s8_t string;
    };

    i32 cap;
    ui_caret_t caret;
};

typedef struct ui_box_t ui_box_t;
struct ui_box_t {
    ui_box_t *next;
    ui_box_t *prev;
    ui_box_t *first;
    ui_box_t *last;
    ui_box_t *parent;
    i32       node_count;

    ui_code_loc_t loc;
    s8_t          string;

    ui_box_flags_t  flags;
    b8              created_new;
    ui_custom_draw_t *custom_draw;
    UI_DECL_BOX_MEMBERS

    r2f32_t full_rect;
    r2f32_t rect;

    // state
    ui_id_t   id;
    ui_box_t *hash_next;
    ui_box_t *hash_prev;
    u64       last_touched_event_id;

    f32 hot_t;
    f32 active_t;

    r2f32_t final_rect;
    b32     expanded;

    ui_text_input_t text_input;
};

typedef struct ui_signal_t ui_signal_t;
struct ui_signal_t {
    ui_box_t *box;
    b8 clicked;
    b8 dragging;
};

typedef struct ui_t ui_t;
struct ui_t {
    app_frame_t *frame;

    // building
    ui_box_t root;
    ui_box_t *top;
    app_event_t *event;

    UI_DECL_STACKS

    // allocation
    ma_arena_t *box_arena;
    i32 allocated_boxes;
    ui_box_t *free_first;
    ui_box_t *hash_first;
    ui_box_t *hash_last;

    // interaction
    ui_id_t hot;
    ui_id_t active;
    ui_id_t focus;

    // drawing
    r2f32_t clip_rect;
};

ui_t *ui;

gb_read_only ui_id_t ui_null_id;
gb_read_only ui_box_t ui_null_box;
gb_read_only ui_box_flags_t ui_null_flags;

fn b32 ui_is_null_id(ui_id_t id) { return id.value == 0; }
fn b32 ui_is_null_box(ui_box_t *box) { return box->id.value == 0; }
fn b32 ui_is_hot_box(ui_box_t *box) { return !ui_is_null_box(box) && box->id.value == ui->hot.value; }
fn b32 ui_is_active_box(ui_box_t *box) { return !ui_is_null_box(box) && box->id.value == ui->active.value; }
fn b32 ui_is_focused_box(ui_box_t *box) { return !ui_is_null_box(box) && box->id.value == ui->focus.value; }

#define ev_left(ev) ((ev)->mouse_button == app_mouse_button_left)
#define ev_left_up(ev) ((ev)->kind == app_event_kind_mouse_up && ev_left(ev))
#define ev_left_down(ev) ((ev)->kind == app_event_kind_mouse_down && ev_left(ev))

fn void ui_set_rect(ui_box_t *box, r2f32_t rect) { box->rect = box->full_rect = rect; }

#define UILOC (ui_code_loc_t){.file = __FILE__, .line = __LINE__, .counter = __COUNTER__}
#define ui_em(x) ((x) * rn_state.main_font->size)
#define ui_max 200000000.f
#define ui_box_flags(...) (ui_box_flag_t){__VA_ARGS__}

fn ui_id_t ui_id(s8_t string);
fn ui_id_t ui_idf(char *str, ...);
fn v2f32_t ui_aligned_text_pos(ui_text_align_t text_align, r2f32_t rect, s8_t string);