type RecipeMarkdownInput = {
  title: string;
  description: string | null;
  baseServings: number;
  prepMins: number | null;
  cookMins: number | null;
  difficulty: "easy" | "medium" | "hard" | null;
  sourceUrl: string | null;
  ingredients: Array<{ rawName: string; quantity: string | null; unit: string | null; note: string | null }>;
  steps: Array<{ instruction: string; timerSeconds: number | null; appliesTo?: string[] }>;
  isBatchCook?: boolean;
  batchDishes?: Array<{
    name: string;
    fridgeDays: number;
    freezerFriendly: boolean;
    freezerNote: string | null;
    dayOfInstructions: string;
  }>;
};

function formatQuantity(quantity: string | null, unit: string | null): string {
  return [quantity, unit].filter(Boolean).join(" ");
}

export function recipeToMarkdown(recipe: RecipeMarkdownInput): string {
  const lines: string[] = [`# ${recipe.title}`, ""];

  if (recipe.description) {
    lines.push(recipe.description, "");
  }

  const meta: string[] = [`Servings: ${recipe.baseServings}`];
  if (recipe.prepMins) meta.push(`Prep: ${recipe.prepMins} min`);
  if (recipe.cookMins) meta.push(`Cook: ${recipe.cookMins} min`);
  if (recipe.difficulty) meta.push(`Difficulty: ${recipe.difficulty}`);
  lines.push(meta.join(" · "), "");

  if (recipe.ingredients.length > 0) {
    lines.push("## Ingredients", "");
    for (const ing of recipe.ingredients) {
      const qty = formatQuantity(ing.quantity, ing.unit);
      const note = ing.note ? ` (${ing.note})` : "";
      lines.push(`- ${qty ? `${qty} ` : ""}${ing.rawName}${note}`);
    }
    lines.push("");
  }

  if (recipe.steps.length > 0) {
    lines.push("## Instructions", "");
    if (recipe.isBatchCook) {
      let lastLabel = "";
      let n = 0;
      for (const step of recipe.steps) {
        const label = !step.appliesTo || step.appliesTo.length === 0 ? "Prep" : step.appliesTo.join(" + ");
        if (label !== lastLabel) {
          if (lastLabel) lines.push("");
          lines.push(`### ${label}`, "");
          lastLabel = label;
          n = 0;
        }
        n += 1;
        lines.push(`${n}. ${step.instruction}`);
      }
    } else {
      recipe.steps.forEach((step, i) => {
        const timer = step.timerSeconds ? ` (${Math.round(step.timerSeconds / 60)} min)` : "";
        lines.push(`${i + 1}. ${step.instruction}${timer}`);
      });
    }
    lines.push("");
  }

  if (recipe.isBatchCook && recipe.batchDishes && recipe.batchDishes.length > 0) {
    lines.push("## Dishes & storage", "");
    for (const dish of recipe.batchDishes) {
      const storage = [`Fridge: ${dish.fridgeDays}d`];
      if (dish.freezerFriendly) storage.push("Freezer-friendly");
      lines.push(`**${dish.name}**`, storage.join(" · ") + (dish.freezerNote ? ` — ${dish.freezerNote}` : ""));
      lines.push(`On the day: ${dish.dayOfInstructions}`, "");
    }
  }

  if (recipe.sourceUrl) {
    lines.push(`Source: ${recipe.sourceUrl}`);
  }

  return lines.join("\n").trim() + "\n";
}