LuaScript/src/main/java/org/openautonomousconnection/luascript/fx/FxCssHost.java

package org.openautonomousconnection.luascript.fx;

import javafx.scene.web.WebEngine;
import org.openautonomousconnection.luascript.hosts.CssHost;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;

/**
 * CSS host via internal JS bridge.
 */
public final class FxCssHost implements CssHost {

    private final WebEngine engine;
    private final FxDomHost dom;

    public FxCssHost(WebEngine engine, FxDomHost dom) {
        this.engine = Objects.requireNonNull(engine, "engine");
        this.dom = Objects.requireNonNull(dom, "dom");
    }

    @Override
    public String getComputedStyle(String elementId, String property) {
        Objects.requireNonNull(elementId, "elementId");
        Objects.requireNonNull(property, "property");

        return FxThreadBridge.callAndWait(() -> FxWebBridge.callWithJs(engine, () -> {
            dom.requireDocument();

            String script = ""
                    + "(function(){"
                    + "  var id=" + FxWebBridge.toJsLiteral(elementId) + ";"
                    + "  var prop=" + FxWebBridge.toJsLiteral(property) + ";"
                    + "  var el=document.getElementById(id);"
                    + "  if(!el) throw new Error('Unknown element id: '+id);"
                    + "  var cs=getComputedStyle(el);"
                    + "  var v=cs.getPropertyValue(prop) || cs[prop] || '';"
                    + "  return String(v);"
                    + "})();";

            Object ret = engine.executeScript(script);
            return ret == null ? "" : String.valueOf(ret);
        }));
    }

    @Override
    public Map<String, String> getComputedStyles(String elementId, String[] properties) {
        Objects.requireNonNull(elementId, "elementId");
        Objects.requireNonNull(properties, "properties");

        Map<String, String> out = new LinkedHashMap<>();
        for (String p : properties) {
            if (p == null || p.isBlank()) continue;
            out.put(p, getComputedStyle(elementId, p));
        }
        return out;
    }

    @Override
    public void setInlineStyle(String elementId, String property, String value) {
        Objects.requireNonNull(elementId, "elementId");
        Objects.requireNonNull(property, "property");

        FxThreadBridge.runAndWait(() -> FxWebBridge.runWithJs(engine, () -> {
            dom.requireDocument();

            String v = value == null ? "" : value;

            String script = ""
                    + "(function(){"
                    + "  var id=" + FxWebBridge.toJsLiteral(elementId) + ";"
                    + "  var prop=" + FxWebBridge.toJsLiteral(property) + ";"
                    + "  var val=" + FxWebBridge.toJsLiteral(v) + ";"
                    + "  var el=document.getElementById(id);"
                    + "  if(!el) throw new Error('Unknown element id: '+id);"
                    + "  if(!val){ el.style.removeProperty(prop); return null; }"
                    + "  el.style.setProperty(prop, val);"
                    + "  return null;"
                    + "})();";

            engine.executeScript(script);
        }));
    }

    @Override
    public String getInlineStyle(String elementId, String property) {
        Objects.requireNonNull(elementId, "elementId");
        Objects.requireNonNull(property, "property");

        return FxThreadBridge.callAndWait(() -> FxWebBridge.callWithJs(engine, () -> {
            dom.requireDocument();

            String script = ""
                    + "(function(){"
                    + "  var id=" + FxWebBridge.toJsLiteral(elementId) + ";"
                    + "  var prop=" + FxWebBridge.toJsLiteral(property) + ";"
                    + "  var el=document.getElementById(id);"
                    + "  if(!el) throw new Error('Unknown element id: '+id);"
                    + "  var v=el.style.getPropertyValue(prop) || '';"
                    + "  return String(v);"
                    + "})();";

            Object ret = engine.executeScript(script);
            return ret == null ? "" : String.valueOf(ret);
        }));
    }

    @Override
    public void setCssVariable(String elementId, String name, String value) {
        Objects.requireNonNull(name, "name");
        if (!name.trim().startsWith("--")) throw new IllegalArgumentException("CSS variable must start with '--': " + name);
        setInlineStyle(elementId, name.trim(), value);
    }

    @Override
    public String getCssVariable(String elementId, String name) {
        Objects.requireNonNull(name, "name");
        if (!name.trim().startsWith("--")) throw new IllegalArgumentException("CSS variable must start with '--': " + name);
        return getComputedStyle(elementId, name.trim());
    }
}