import * as htmlparser from "htmlparser2"
export interface HTMLTag extends ElementStructure {
    name: string
    attrs: {
        [index: string]: string
    }
    type: "element"
}
export interface HTMLText extends ElementStructure {
    content: string
    type: "text"
}
export interface ElementStructure {
    type: "element" | "text" | "style" | "script"
    children: ElementStructure[]
}

export function parseHTMLStructure(content: string): ElementStructure[] {
    let root: HTMLTag = { type: "element", children: [], attrs: {}, name: "root" }
    let stack = []
    let cur: ElementStructure = root
    let parser = new htmlparser.Parser({
        onopentag: (name, attrs) => {
            let el: HTMLTag
            el = {
                type: "element", attrs,
                children: [],
                name
            } as HTMLTag
            cur.children.push(el)
            stack.push(cur)
            cur = el
        },
        ontext: (text: string) => {
            cur.children.push({
                type: "text",
                content: text,
                children: null
            } as ElementStructure)
        },
        onclosetag: () => {
            cur = stack.pop()
        }
    }, { decodeEntities: true })
    parser.end(content)
    return root.children
}
export function structureToString(s: ElementStructure) {
    if (s.type === "text") return s["content"]
    let result = ""
    for (let child of s["children"] || []) {
        result += structureToString(child)
    }
    return result
}