import { Styles } from "./";
import * as fastXmlParser from "fast-xml-parser";
import { ImportedXmlComponent, ImportedRootElementAttributes } from "./../../file/xml-components";

const parseOptions = {
    ignoreAttributes: false,
    attributeNamePrefix: "",
    attrNodeName: "_attr",
};

export class ExternalStylesFactory {
    /**
     * Creates new Style based on the given styles.
     * Parses the styles and convert them to XmlComponent.
     * Example content from styles.xml:
     * <?xml version="1.0">
     * <w:styles xmlns:mc="some schema" ...>
     *
     *   <w:style w:type="paragraph" w:styleId="Heading1">
     *           <w:name w:val="heading 1"/>
     *           .....
     *   </w:style>
     *
     *   <w:style w:type="paragraph" w:styleId="Heading2">
     *           <w:name w:val="heading 2"/>
     *           .....
     *   </w:style>
     *
     *   <w:docDefaults>Or any other element will be parsed to</w:docDefaults>
     *
     * </w:styles>
     * @param externalStyles context from styles.xml
     */
    public newInstance(externalStyles: string): Styles {
        const xmlStyles = fastXmlParser.parse(externalStyles, parseOptions)["w:styles"];
        // create styles with attributes from the parsed xml
        const importedStyle = new Styles(new ImportedRootElementAttributes(xmlStyles._attr));

        // convert other elements (not styles definitions, but default styles and so on ...)
        Object.keys(xmlStyles)
            .filter((element) => element !== "_attr" && element !== "w:style")
            .forEach((element) => {
                importedStyle.push(new ImportedXmlComponent(element, xmlStyles[element]._attr));
            });

        // convert the styles one by one
        xmlStyles["w:style"]
            .map((style) => this.convertElement("w:style", style))
            .forEach(importedStyle.push.bind(importedStyle));

        return importedStyle;
    }

    convertElement(elementName: string, element: any): ImportedXmlComponent {
        const xmlElement = new ImportedXmlComponent(elementName, element._attr);
        if (typeof element === "object") {
            Object.keys(element)
                .filter((key) => key !== "_attr")
                .map((item) => this.convertElement(item, element[item]))
                .forEach(xmlElement.push.bind(xmlElement));
        }
        return xmlElement;
    }
}