import type { NamespaceTable } from "@/ua/NameSpaceTable";

export class XMLElem {
    name: string;
    value: string;
    elements: XMLElem[]=[];
    attributes: XmlAttr[]=[];

    constructor(name: string, value?:string) {
        this.name=name;
        this.value=value||'';
    }

    public add(elem: XMLElem): XMLElem {
        this.elements.push(elem);
        return elem;
    }

    public attr(name:string, value: string|boolean|undefined|null): XMLElem {
        if(value===undefined||value===null)
            return this; //skip undefined/null values
        this.attributes.push(new XmlAttr(name, value?.toString()));
        return this;
    }

    public elem(name:string, value: XMLElem|string|boolean|undefined|null): XMLElem {
        if(value===undefined||value===null)
            return this; //skip undefined/null values
        if(value instanceof XMLElem)
            this.elements.push(value);
        this.elements.push(new XMLElem(name, value?.toString()));
        return this;
    }

    public toString(level: number=0): string {
        let s="";
        if(level==0) {
            s+='<?xml version="1.0" encoding="utf-8" ?>\n'
        }
        s+=" ".repeat(level+1) + `<${this.name} `;
        for(const attr of this.attributes) {
            if(attr.value==undefined)
                continue;
            s+=`${attr.name}="${this.escapeXml(attr.value)}" `;
        }
        s=s.slice(0, -1);
        s+=`>`
        for(const elem of this.elements) {
            s+="\n"+" ".repeat(level) + elem.toString(level+1);
        }
        if(this.value && this.elements.length==0) {
            s+=this.escapeXml(this.value);
        }
        if(this.elements.length>0)
            s+="\n" + " ".repeat(level);
        s+=`</${this.name}>`
        return s;
    }

    private escapeXml(unsafe: string) {
        return unsafe.replace(/[<>&'"]/g, (c: string):string => {
            switch (c) {
                case '<': return '&lt;';
                case '>': return '&gt;';
                case '&': return '&amp;';
                case '\'': return '&apos;';
                case '"': return '&quot;';
            }
            return c;
        });
    }
}

class XmlAttr {
    constructor(public name: string, 
                public value: string) {
                }

}

export interface IToXML {
    toXML(lnst: NamespaceTable, gnst: NamespaceTable) :XMLElem;
}