import { Element } from "xml-js";
import * as xml from "xml";

import { Formatter } from "@export/formatter";
import { XmlComponent } from "@file/xml-components";

import { IPatch, PatchType } from "./from-docx";
import { toJson } from "./util";
import { IRenderedParagraphNode } from "./run-renderer";
import { replaceTokenInParagraphElement } from "./paragraph-token-replacer";
import { findRunElementIndexWithToken, splitRunElement } from "./paragraph-split-inject";

const formatter = new Formatter();

const SPLIT_TOKEN = "ɵ";

export const replacer = (json: Element, patch: IPatch, patchText: string, renderedParagraphs: readonly IRenderedParagraphNode[]): Element => {
    for (const renderedParagraph of renderedParagraphs) {
        const textJson = patch.children.map((c) => toJson(xml(formatter.format(c as XmlComponent)))).map((c) => c.elements![0]);

        if (patch.type === PatchType.DOCUMENT) {
            const parentElement = goToParentElementFromPath(json, renderedParagraph.path);
            const elementIndex = getLastElementIndexFromPath(renderedParagraph.path);
            // eslint-disable-next-line functional/immutable-data, prefer-destructuring
            parentElement.elements?.splice(elementIndex, 1, ...textJson);
        } else if (patch.type === PatchType.PARAGRAPH) {
            // Hard case where the text is only part of the paragraph
            const paragraphElement = goToElementFromPath(json, renderedParagraph.path);

            replaceTokenInParagraphElement({
                paragraphElement,
                renderedParagraph,
                originalText: patchText,
                replacementText: SPLIT_TOKEN,
            });

            const index = findRunElementIndexWithToken(paragraphElement, SPLIT_TOKEN);

            const { left, right } = splitRunElement(paragraphElement.elements![index], SPLIT_TOKEN);
            // eslint-disable-next-line functional/immutable-data
            paragraphElement.elements!.splice(index, 1, left, ...textJson, right);
        }
    }

    return json;
};

const goToElementFromPath = (json: Element, path: readonly number[]): Element => {
    let element = json;

    // We start from 1 because the first element is the root element
    // Which we do not want to double count
    for (let i = 1; i < path.length; i++) {
        const index = path[i];
        const nextElements = element.elements;

        if (!nextElements) {
            throw new Error("Could not find element");
        }

        element = nextElements[index];
    }

    return element;
};

const goToParentElementFromPath = (json: Element, path: readonly number[]): Element =>
    goToElementFromPath(json, path.slice(0, path.length - 1));

const getLastElementIndexFromPath = (path: readonly number[]): number => path[path.length - 1];