/* -*- mode: javascript -*-
  Oembed, outer script,
  run three.
 */

var oembedhost = new URL('/', 'https://oembed.rz.uni-kiel.de/oembed.js'); // document.currentScript.src);

var shimfile = new URL("shim.html", document.currentScript.src);
var libfile  = new URL("iframeResizer.min.js", document.currentScript.src);


function collectCSS(a, host){
    if (!host.endsWith("uni-kiel.de")){
	// we cannot trust this page to look ok
	// if we mess with fonts, colors, etc.
	return [];
    }

    const IFRAME_CLONEABLE_CSS_PROPERTIES = [
	"font-family", "font-size", "font-weight", "font-shape", "font-style", "font-variant",
	"letter-spacing", "line-height", "text-decoration",
	"color", "cursor"
    ];
    const CSS_TEMPLATES = [
	['body', a.parentNode||document.body],
	['a:link', a]
    ];
    
    var extraStyleList = [];

    // 1. get all the font rules.
    for (const stylesh of document.styleSheets){
	try {
	    for (const rule of stylesh.cssRules){
		if (rule instanceof CSSFontFaceRule){
		    // I was convinced we didn't need to handle relative URI
		    // problems here, but apparently I was wrong?
		    extraStyleList.push(rule.cssText.replace(/url\(["']([^)]*)["']\)/g,
							     (match, p1)=>{return `url("${new URL(p1, document.baseURI)}")`}));
		}
	    }
	} catch(e){ console.error(e); }
    }

    // 2. copy things according to other elements.
    // (we probably can't copy link attributes, though)
    for ([selector, elem] of CSS_TEMPLATES){
	var styles = window.getComputedStyle(elem);
	extraStyleList.push(
	    ((rs) => `${selector} {${rs}}`)(IFRAME_CLONEABLE_CSS_PROPERTIES.map(
		(p) => `${p}:${styles.getPropertyValue(p)}`
	    ).join(';'))
	);
    }

    return extraStyleList;
}

function oembedify(a){
    // step 1: useless validation
    if (a.href.indexOf(a.dataset.domainMustMatch||'') == -1){
	console.error("bad oembed link: target "+a.href+" does not match required domain "+a.dataset.domainMustMatch);
	return;
    }

    var ifr = document.createElement('iframe');
    Object.assign(ifr, {
	referrerPolicy: 'unsafe-url',
	src: shimfile,
	classList: ["oembedded"],
    });
    Object.assign(ifr.style, {
	borderWidth: 0,
	outlineWidth: 0,
	margin: 0,
	padding: 0,
	width: a?.style?.width || "100%",
    });

    // setup setup message, including extra CSS styles, if needed.
    var msg = {
	oembedsetup: 1,
	//vvv client window shouldn't trust us.
	//oembedhost: oembedprovider,
	//clientlib: new URL("iframeResizer.contentWindow.min.js", oembedhost).href,
	language: (document.documentElement.lang || document.documentElement.body.lang || navigator.language || 'de').split('-',1)[0],
	url: a.href,
	css: collectCSS(a, new URL(a.href).host),
    };
    if (a.style.width)
	msg.width = a.style.width;
    if (a.style.height)
	msg.height= a.style.height;
    
    ifr.addEventListener('load', (ev) => {
	ifr.contentWindow.postMessage(msg,
				      oembedhost.origin);
    });
    
    a.parentNode.replaceChild(ifr, a);
}

// load the outer code that will actually resize.

window.addEventListener('load', (ev) => {
    import (libfile).then(() => {
	document.querySelectorAll('a.oembed').forEach(oembedify);
	iFrameResize( {checkOrigin: [shimfile.origin, 'https://oembed.rz.uni-kiel.de']}, 'iframe.oembedded' );
    });
});