// widget_jsontable.ysl2

template "widget[@type='JsonTable']", mode="widget_class"
    ||
    class JsonTableWidget extends Widget{
        // arbitrary defaults to avoid missing entries in query
        cache = [0,100,50];
        init() {
            this.spread_json_data_bound = this.spread_json_data.bind(this);
            this.handle_http_response_bound = this.handle_http_response.bind(this);
            this.fetch_error_bound = this.fetch_error.bind(this);
            this.promised = false;
        }

        handle_http_response(response) {
            if (!response.ok) {
              console.log("HTTP error, status = " + response.status);
            }
            return response.json();
        }

        fetch_error(e){
            console.log("HTTP fetch error, message = " + e.message + "Widget:" + this.element_id);
        }

        do_http_request(...opt) {
            this.abort_controller = new AbortController();
            const query = {
                args: this.args,
                range: this.cache[1],
                position: this.cache[2],
                visible: this.visible,
                extra: this.cache.slice(4),
                options: opt
            };

            const options = {
                 method: 'POST',
                 body: JSON.stringify(query),
                 headers: {'Content-Type': 'application/json'},
                 signal: this.abort_controller.signal
            };

            return fetch(this.args[0], options)
                    .then(this.handle_http_response_bound)
                    .then(this.spread_json_data_bound)
                    .catch(this.fetch_error_bound);

        }
        unsub(){
            this.abort_controller.abort();
            super.unsub();
        }

        dispatch(value, oldval, index) {

            if(this.cache[index] != value)
                this.cache[index] = value;
            else
                return;

            if(!this.promised){
                this.promised = true;
                this.do_http_request().finally(() => {
                    this.promised = false;
                });
            }
        }
        make_on_click(...options){
            let that = this;
            return function(evt){
                that.do_http_request(...options);
            }
        }
        // on_click(evt, ...options) {
        //     this.do_http_request(...options);
        // }
    }
    ||

template "svg:*", mode="json_table_elt_render" {
    error > JsonTable Widget can't contain element of type «local-name()».
}


const "hmi_textstylelists_descs", "$parsed_widgets/widget[@type = 'TextStyleList']";
const "hmi_textstylelists", "$hmi_elements[@id = $hmi_textstylelists_descs/@id]";

const "textstylelist_related" foreach "$hmi_textstylelists" list {
    attrib "listid" value "@id";
    foreach "func:refered_elements(.)" elt {
        attrib "eltid" value "@id";
    }
}
const "textstylelist_related_ns", "exsl:node-set($textstylelist_related)";

def "func:json_expressions" {
    param "expressions";
    param "label";

    // compute javascript expressions to access JSON data
    // desscribed in given svg element's "label"
    // knowing that parent element already has given "expressions".

    choose {
        when "$label" {
            const "suffixes", "str:split($label)";
            const "res" foreach "$suffixes" expression {
                const "suffix",".";
                const "pos","position()";
                // take last available expression (i.e can have more suffixes than expressions)
                const "expr","$expressions[position() <= $pos][last()]/expression";
                choose {
                    when "contains($suffix,'=')" {
                        const "name", "substring-before($suffix,'=')";
                        if "$expr/@name[. != $name]"
                            error > JsonTable : missplaced '=' or inconsistent names in Json data expressions.
                        attrib "name" value "$name";
                        attrib "content" > «$expr/@content»«substring-after($suffix,'=')»
                    }
                    otherwise {
                        copy "$expr/@name";
                        attrib "content" > «$expr/@content»«$suffix»
                    }
                }
            }
            result "exsl:node-set($res)";
        }
        // Empty labels are ignored, expressions are then passed as-is.
        otherwise result "$expressions";
    }

}

const "initexpr" expression attrib "content" > jdata
const "initexpr_ns", "exsl:node-set($initexpr)";

template "svg:use", mode="json_table_elt_render" {
    param "expressions";
    // cloned element must be part of a HMI:List
    const "targetid", "substring-after(@xlink:href,'#')";
    const "from_list", "$hmi_lists[(@id | */@id) = $targetid]";

    choose {
        when "count($from_list) > 0" {
            |         id("«@id»").setAttribute("xlink:href",
            // obtain new target id from HMI:List widget
            |             "#"+hmi_widgets["«$from_list/@id»"].items[«$expressions/expression[1]/@content»]);
        }
        otherwise
            warning > Clones (svg:use) in JsonTable Widget must point to a valid HMI:List widget or item. Reference "«@xlink:href»" is not valid and will not be updated.
    }
}

template "svg:text", mode="json_table_elt_render" {
    param "expressions";
    const "value_expr", "$expressions/expression[1]/@content";
    const "original", "@original";
    const "from_textstylelist", "$textstylelist_related_ns/list[elt/@eltid = $original]";
    choose {

        when "count($from_textstylelist) > 0" {
            const "content_expr", "$expressions/expression[2]/@content";
            if "string-length($content_expr) = 0 or $expressions/expression[2]/@name != 'textContent'"
                error > Clones (svg:use) in JsonTable Widget pointing to a HMI:TextStyleList widget or item must have a "textContent=.someVal" assignement following value expression in label.
            |         {
            |           let elt = id("«@id»");
            |           elt.textContent = String(«$content_expr»);
            |           elt.style = hmi_widgets["«$from_textstylelist/@listid»"].styles[«$value_expr»];
            |         }
        }
        otherwise {
            |         id("«@id»").textContent = String(«$value_expr»);
        }
    }
}


// only labels comming from Json widget are counted in
def "func:filter_non_widget_label" {
    param "elt";
    param "widget_elts";
    const "eltid" choose {
        when "$elt/@original" value "$elt/@original";
        otherwise value "$elt/@id";
    }
    result "$widget_elts[@id=$eltid]/@inkscape:label";
}

template "svg:*", mode="json_table_render_except_comments"{
    param "expressions";
    param "widget_elts";

    const "label", "func:filter_non_widget_label(., $widget_elts)";
    // filter out "# commented" elements
    if "not(starts-with($label,'#'))" 
        apply ".", mode="json_table_render"{
            with "expressions", "$expressions";
            with "widget_elts", "$widget_elts";
            with "label", "$label";
        }
}


template "svg:*", mode="json_table_render" {
    param "expressions";
    param "widget_elts";
    param "label";

    const "new_expressions", "func:json_expressions($expressions, $label)";

    const "elt",".";
    foreach "$new_expressions/expression[position() > 1][starts-with(@name,'onClick')]"
    |         id("«$elt/@id»").onclick = this.make_on_click('«@name»', «@content»);

    apply ".", mode="json_table_elt_render"
        with "expressions", "$new_expressions";
}

template "svg:g", mode="json_table_render" {
    param "expressions";
    param "widget_elts";
    param "label";

    // use intermediate variables for optimization
    const "varprefix" > obj_«@id»_
    |         try {

    foreach "$expressions/expression"{
    |          let «$varprefix»«position()» = «@content»;
    |          if(«$varprefix»«position()» == undefined) {
    |               throw null;
    |          }
    }

    // because we put values in a variables, we can replace corresponding expression with variable name
    const "new_expressions" foreach "$expressions/expression" xsl:copy {
        copy "@name";
        attrib "content" > «$varprefix»«position()»
    }

    // revert hiding in case it did happen before
    |           id("«@id»").style = "«@style»";

    apply "*", mode="json_table_render_except_comments" {
        with "expressions", "func:json_expressions(exsl:node-set($new_expressions), $label)";
        with "widget_elts", "$widget_elts";
    }
    |         } catch(err) {
    |           id("«@id»").style = "display:none";
    |         }
}

template "widget[@type='JsonTable']", mode="widget_defs" {
    param "hmi_element";
    labels("data");
    optional_labels("forward backward cursor");
    const "data_elt", "$result_svg_ns//*[@id = $hmi_element/@id]/*[@inkscape:label = 'data']";
    |     visible: «count($data_elt/*[@inkscape:label])»,
    |     spread_json_data: function(janswer) {
    |         let [range,position,jdata] = janswer;
    |         [[1, range], [2, position], [3, this.visible]].map(([i,v]) => {
    |              this.apply_hmi_value(i,v);
    |              this.cache[i] = v;
    |         });
    apply "$data_elt", mode="json_table_render_except_comments" {
        with "expressions","$initexpr_ns";
        with "widget_elts","$hmi_element/*[@inkscape:label = 'data']/descendant::svg:*";
    }
    |     }
}