import type { PatchArray, PatchName, PatchPage } from "./patcher";

export class PatcherUtils {
    static indexOf(txt: string, searchString: string, startIndex: number, maxRange=0, after=false): number {
        if (startIndex < 0) {
            return -1;
        }

        const index = txt.indexOf(searchString, startIndex);
        if (index < 0 || (maxRange && index - startIndex > maxRange)) {
            return -1;
        }

        return after ? index + searchString.length : index;
    }

    static lastIndexOf(txt: string, searchString: string, startIndex: number, maxRange=0, after=false): number {
        if (startIndex < 0) {
            return -1;
        }

        const index = txt.lastIndexOf(searchString, startIndex);
        if (index < 0 || (maxRange && startIndex - index > maxRange)) {
            return -1;
        }

        return after ? index + searchString.length : index;
    }

    static insertAt(txt: string, index: number, insertString: string): string {
        return txt.substring(0, index) + insertString + txt.substring(index);
    }

    static replaceWith(txt: string, index: number, fromString: string, toString: string): string {
        return txt.substring(0, index) + toString + txt.substring(index + fromString.length);
    }

    static filterPatches(patches: Array<string | false>): PatchArray {
        return patches.filter((item): item is PatchName => !!item);
    }

    static patchBeforePageLoad(str: string, page: PatchPage): string | false {
        let text = `chunkName:()=>"${page}-page",`;
        if (!str.includes(text)) {
            return false;
        }

        str = str.replace('requireAsync(e){', `requireAsync(e){window.BX_EXPOSED.beforePageLoad("${page}");`);
        str = str.replace('requireSync(e){', `requireSync(e){window.BX_EXPOSED.beforePageLoad("${page}");`);

        return str;
    }

    private static isVarCharacter(char: string) {
        const code = char.charCodeAt(0);

        // Check for uppercase letters (A-Z)
        const isUppercase = code >= 65 && code <= 90;

        // Check for lowercase letters (a-z)
        const isLowercase = code >= 97 && code <= 122;

        // Check for digits (0-9)
        const isDigit = code >= 48 && code <= 57;

        // Check for special characters '_' and '$'
        const isSpecial = char === '_' || char === '$';

        return isUppercase || isLowercase || isDigit || isSpecial;
    }

    static getVariableNameBefore(str: string, index: number) {
        if (index < 0) {
            return null;
        }

        const end = index;
        let start = end - 1;
        while (PatcherUtils.isVarCharacter(str[start])) {
            start -= 1;
        }

        return str.substring(start + 1, end);
    }

    static getVariableNameAfter(str: string, index: number) {
        if (index < 0) {
            return null;
        }

        const start = index;
        let end = start + 1;
        while (PatcherUtils.isVarCharacter(str[end])) {
            end += 1;
        }

        return str.substring(start, end);
    }
}