// widget_dropdown.ysl2

template "widget[@type='DropDown']", mode="widget_defs" {
    param "hmi_element";
    labels("text box");
||    
    dispatch: function(value) {
        if(!this.opened) this.set_selection(value);
    },
    init: function() {
        this.element.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_click()");
        this.text_bbox = this.text_elt.getBBox()
        this.box_bbox = this.box_elt.getBBox()
        lmargin = this.text_bbox.x - this.box_bbox.x;
        tmargin = this.text_bbox.y - this.box_bbox.y;
        rmargin = this.box_bbox.width - this.text_bbox.width - lmargin;
        bmargin = this.box_bbox.height - this.text_bbox.height - tmargin;
        this.margins = [lmargin, tmargin, rmargin, bmargin].map(x => Math.max(x,0));
        this.content = ["one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
                        "eleven", "twelve", "thirteen", "fourteen", "fifteen"];
        //this.content = ["one", "two", "three", "four", "5", "6"];
        this.menu_offset = 0;
        this.lift = 0;
        this.opened = false;
    },
    on_selection_click: function(selection) {
        this.set_selection(selection);
    },
    on_click: function() {
        if(this.opened){
            //this.close();
        }else{
            this.open();
        }
    },
    on_backward_click:function(){
        this.move(false);
    },
    on_forward_click:function(){
        this.move(true);
    },
    set_selection: function(value) {
        this.text_elt.firstElementChild.textContent = 
          (value >= 0 && value < this.content.length) ?
            this.content[value] : "?"+String(value)+"?";
    },
    grow_text: function(up_to) {
        let count = 1;
        let txt = this.text_elt; 
        let first = txt.firstElementChild;
        let bounds = svg_root.getBoundingClientRect(); 
        this.lift = 0;
        while(count < up_to) {
            let next = first.cloneNode();
            next.removeAttribute("y");
            next.setAttribute("dy", "1.1em");
            next.textContent = "...";
            txt.appendChild(next);
            let rect = txt.getBoundingClientRect();
            if(rect.bottom > bounds.bottom){
                let backup = first.getAttribute("dy");
                first.setAttribute("dy", "-"+String((this.lift+1)*1.1)+"em");
                rect = txt.getBoundingClientRect();
                if(rect.top > bounds.top){
                    this.lift += 1;
                } else {
                    if(backup)
                        first.setAttribute("dy", backup);
                    else
                        first.removeAttribute("dy");
                    txt.removeChild(next);
                    return count;
                }
            }
            count++;
        }
        return count;
    },
    close: function(){
        this.reset_text();
        this.reset_box();
        this.opened = false;
    },
    set_complete_text: function(){
        let spans = this.text_elt.children; 
        let c = 0;
        for(let item of this.content){
            let span=spans[c];
            span.textContent = item;
            span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_selection_click("+c+")");
            c++;
        }
    },
    move: function(forward){
        let contentlength = this.content.length;
        let spans = this.text_elt.children; 
        let spanslength = spans.length;
        if(this.menu_offset != 0) spanslength--;
        if(this.menu_offset < contentlength - 1) spanslength--;
        if(forward){
            this.menu_offset = Math.min(
                contentlength - spans.length + 1, 
                this.menu_offset + spanslength);
        }else{
            this.menu_offset = Math.max(
                0, 
                this.menu_offset - spanslength);
        }
        console.log(this.menu_offset);
        this.set_partial_text();
    },
    set_partial_text: function(){
        let spans = this.text_elt.children; 
        let contentlength = this.content.length;
        let spanslength = spans.length;
        let i = this.menu_offset, c = 0;
        while(c < spanslength){
            let span=spans[c];
            if(c == 0 && i != 0){
                span.textContent = "↑  ↑  ↑";
                span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_backward_click()");
            }else if(c == spanslength-1 && i < contentlength - 1){
                span.textContent = "↓  ↓  ↓";
                span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_forward_click()");
            }else{
                span.textContent = this.content[i];
                span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_selection_click("+i+")");
                i++;
            }
            c++;
        }
    },
    open: function(){
        let length = this.content.length;
        this.reset_text();
        let slots = this.grow_text(length);
        if(slots == length) {
            this.set_complete_text();
        } else {
            this.set_partial_text();
        }
        this.adjust_box_to_text();
        /* TODO disable interaction with background */
        this.opened = true;
    },
    reset_text: function(){
        let txt = this.text_elt; 
        let first = txt.firstElementChild;
        first.removeAttribute("onclick");
        first.removeAttribute("dy");
        for(let span of Array.from(txt.children).slice(1)){
            txt.removeChild(span)
        }
    },
    reset_box: function(){
        let m = this.box_bbox;
        let b = this.box_elt;
        b.x.baseVal.value = m.x;
        b.y.baseVal.value = m.y;
        b.width.baseVal.value = m.width;
        b.height.baseVal.value = m.height;
    },
    adjust_box_to_text: function(){
        let [lmargin, tmargin, rmargin, bmargin] = this.margins;
        let m = this.text_elt.getBBox();
        let b = this.box_elt;
        b.x.baseVal.value = m.x - lmargin;
        b.y.baseVal.value = m.y - tmargin;
        b.width.baseVal.value = lmargin + m.width + rmargin;
        b.height.baseVal.value = tmargin + m.height + bmargin;
    },
||
}

    // |         let p = new DOMPoint(this.box_elt.x.baseVal.value, this.box_elt.y.baseVal.value);
    // |         let k = DOMMatrix.fromMatrix(this.box_elt.getCTM());
    // |         let new_corner = k.transformPoint(p);
    // |         new_corner.y = 0;
    // |         let nc = k.inverse().transformPoint(new_corner);
    // |         this.box_elt.x.baseVal.value = nc.x;
    // |         this.box_elt.y.baseVal.value = nc.y;