import Mustache from "mustache";
import { VariableView } from "./VariableView";
import { hasValidMustacheTags } from "./helperFunctions";

type MustacheIterationOptions = {
  maxPasses?: number;
  detectCycles?: boolean;
};

/**
 * Replaces all mustache tokens recursively until there are none left that can be replaced.
 * @param template 
 * @param param1 
 * @returns 
 */
export function replaceAllMustaches(
    template: string,
    { maxPasses = 20, detectCycles = true }: MustacheIterationOptions = {},
    ): string {
        let current = template;
        let last = ""; // To ensure that the same token isn't replaced twice in a row

        for (let pass = 0; pass < maxPasses; pass += 1) {
            if (hasValidMustacheTags(current)){ // If any {{}} remain...
                if (detectCycles) { // If you check the number of cycles, which you do by default, throw an error and stop
                    if (last === current) {
                        throw new Error(`Render cycle detected at pass ${pass}: "${current}"`);
                    };

                    last = current; // Now the string it's looping over will be checked next time
                };

                const next = Mustache.render(current, VariableView.all);
                
                // If the string's not the same as the current string, set it as the new template and re-loop
                if (next !== current){
                    current = next;                    
                } else {
                    return current; // no more substitutions happened
                }
            } else {
                console.log("passes:",pass)
                return current;
            }
        };

        return current;
};