/*
* Fancy string - immediate mode renderer for colored strings
*/

static Fancy_Color
blend_color(id_color a, f32 t, id_color b){
    Fancy_Color result = {};
    result.index_a = (u16)a;
    result.index_b = (u16)b;
    result.table_a = 1;
    result.table_b = 1;
    result.c_b = (u8)(clamp(0, 255.0f*t, 255.0f));
    result.c_a = 255 - result.c_b;
    return(result);
}

static Fancy_Color
single_color(id_color a){
    Fancy_Color result = {};
    result.index_a = (u16)a;
    result.index_b = 0;
    result.table_a = 1;
    result.table_b = 0;
    result.c_a = 255;
    result.c_b = 0;
    return(result);
}

static Fancy_Color
fancy_from_rgba_color(argb_color color){
    Fancy_Color result = {};
    result.rgba = color;
    result.code = 0;
    return(result);
}

static Fancy_Color
fancy_from_rgba_color(f32 r, f32 g, f32 b, f32 a){
    Fancy_Color result = fancy_from_rgba_color(pack_color4(V4(r, g, b, a)));
    return(result);
}

static Fancy_Color
fancy_resolve_to_rgba(Application_Links *app, Fancy_Color source){
    if (source.code != 0){
        Vec4 a = unpack_color4(finalize_color(app, source.index_a));
        Vec4 b = unpack_color4(finalize_color(app, source.index_b));
        
        f32 ca = (f32)source.c_a/255.0f;
        f32 cb = (f32)source.c_b/255.0f;
        
        Vec4 value = ca*a + cb*b;
        
        source.rgba = pack_color4(value);
        source.code = 0;
    }
    return(source);
}

static Fancy_Color
pass_through_fancy_color(void){
    Fancy_Color result = {};
    return(result);
}

static int_color
int_color_from(Application_Links *app, Fancy_Color source){
    int_color result = {};
    if ((source.c_a == 255) && (source.c_b == 0)){
        result = source.index_a;
    }
    else{
        source = fancy_resolve_to_rgba(app, source);
        result = source.rgba;
    }
    return(result);
}

static bool32
is_valid(Fancy_Color source){
    bool32 result = !((source.code == 0) && (source.rgba == 0));
    return(result);
}

static Fancy_String *
push_fancy_string(Arena *arena, Fancy_String_List *list, String value, Fancy_Color fore){
    Fancy_String *result = push_array(arena, Fancy_String, 1);
    result->value = string_push_copy(arena, value);
    result->fore = fore;
    result->back = pass_through_fancy_color();
    result->pre_margin = 0;
    result->post_margin = 0;
    result->next = 0;
    
    if (list != 0){
        list->last = (list->last ? list->last->next : list->first) = result;
    }
    
    return(result);
}

static Fancy_String *
push_fancy_string(Arena *arena, Fancy_String_List *list, String value){
    return(push_fancy_string(arena, list, value, pass_through_fancy_color()));
}

static Vec2
draw_fancy_string(Application_Links *app, Face_ID font_id, Fancy_String *string, Vec2 P,
                  int_color fore, int_color back, u32 flags, Vec2 dP){
    for (;string != 0;
         string = string->next){
        Face_ID use_font_id = (string->font_id) ? string->font_id : font_id;
        int_color use_fore = is_valid(string->fore) ? int_color_from(app, string->fore) : fore;
        
        f32 adv = get_string_advance(app, use_font_id, string->value);
        
        // TODO(casey): need to fill the background here, but I don't know the line height,
        // and I can't actually render filled shapes, so, like, I can't properly do dP :(
        
        P += (string->pre_margin)*dP;
        draw_string(app, use_font_id, string->value, P, use_fore, flags, dP);
        P += (adv + string->post_margin)*dP;
    }
    return(P);
}