import { existsSync, readFileSync } from "node:fs";
import { join } from "node:path";
import nunjucks from "nunjucks";
import type { ImageSelection, UsageTemplate } from "./types";

const findAppRoot = (): string => {
  const candidates = [join(__dirname, "../../.."), join(__dirname, "../..")];

  for (const candidate of candidates) {
    if (existsSync(join(candidate, "templates.json"))) {
      return candidate;
    }
  }

  throw new Error("Unable to resolve app template root");
};

export class TemplateService {
  private readonly appRoot = findAppRoot();

  private readonly env = nunjucks.configure(join(this.appRoot, "templates"), {
    autoescape: false,
    noCache: true
  });

  private readonly templates: UsageTemplate[] = JSON.parse(
    readFileSync(join(this.appRoot, "templates.json"), "utf8")
  ) as UsageTemplate[];

  public getTemplates(): UsageTemplate[] {
    return this.templates;
  }

  public render(templateFile: string, selection: ImageSelection): string {
    return this.env.render(templateFile, selection);
  }

  public buildSkuExport(skus: string[]): string {
    return `[\n${skus.map((sku) => `\t\"${sku}\"`).join(",\n")}\n]`;
  }
}