import { describe, it, expect } from "vitest";
import {
  loadPromptTemplate,
  renderPrompt,
  type PromptParams,
} from "../promptTemplate.js";

const params: PromptParams = {
  sourceLanguage: "es",
  pos: "noun",
  targetLanguages: ["en", "it", "de", "fr"],
  words: ["suelo", "pared"],
};

describe("renderPrompt", () => {
  it("substitutes every placeholder from the checked-in template", () => {
    const rendered = renderPrompt(loadPromptTemplate(), params);
    expect(rendered).toContain('Source language: Spanish ("es")');
    expect(rendered).toContain('language must be "es"');
    expect(rendered).toContain("Target languages: en, it, de, fr");
    expect(rendered).toContain('"en" | "it" | "de" | "fr"');
    expect(rendered).toContain("suelo\npared");
    expect(rendered).toContain("valid Spanish noun");
    expect(rendered).not.toMatch(/\{\{[A-Z_]+\}\}/);
  });

  it("does not tell the model to exclude a non-source language as target", () => {
    const rendered = renderPrompt(loadPromptTemplate(), params);
    expect(rendered).toContain(
      'Do not include Spanish ("es") as a target_language.',
    );
    expect(rendered).not.toContain(
      "Do not include English as a target_language",
    );
  });

  it("throws when the source language is listed as a target", () => {
    expect(() =>
      renderPrompt(loadPromptTemplate(), {
        ...params,
        targetLanguages: ["en", "es"],
      }),
    ).toThrow(/exclude the source language/);
  });

  it("throws on an empty word batch", () => {
    expect(() =>
      renderPrompt(loadPromptTemplate(), { ...params, words: [] }),
    ).toThrow(/empty word batch/);
  });

  it("throws on unreplaced placeholders", () => {
    expect(() => renderPrompt("hello {{UNKNOWN_TOKEN}}", params)).toThrow(
      /UNKNOWN_TOKEN/,
    );
  });
});