import { HttpError } from "@batch-cooking/error-tools";
import {
  type AllergyView,
  type CreateRecipeInput,
  type DietView,
  ErrorCode,
  type IngredientView,
  type RecipeSummaryView,
  type RecipeTab,
  type RecipeView,
  type UpdateRecipeInput,
} from "@batch-cooking/shared";
import type { Prisma } from "@prisma/client";
import { prisma } from "../../db/prisma.js";

/** Prisma `include` for every query that needs a full {@link RecipeView} — ingredients resolved to their reference data + allergens, steps in order, diet tags, and whether `viewerId` has favorited it. Parameterized by viewer since `favoritedBy` is per-viewer, not a static shape. */
function recipeInclude(viewerId: number) {
  return {
    ingredients: {
      include: {
        ingredient: {
          include: {
            allergies: { include: { allergy: { include: { category: true } } } },
            diets: { include: { diet: true } },
          },
        },
      },
    },
    steps: { orderBy: { order: "asc" } },
    diets: { include: { diet: true } },
    favoritedBy: { where: { userProfileId: viewerId } },
  } satisfies Prisma.RecipeInclude;
}

type RecipeWithDetails = Prisma.RecipeGetPayload<{ include: ReturnType<typeof recipeInclude> }>;
type IngredientWithDetails = RecipeWithDetails["ingredients"][number]["ingredient"];

/** Shapes a Prisma `Ingredient` (with its `allergies`/`diets` relations included) into the public {@link IngredientView} — same aplattening as `reference.service.ts`'s `getIngredients`. */
function toIngredientView(ingredient: IngredientWithDetails): IngredientView {
  return {
    id: ingredient.id,
    key: ingredient.key,
    icon: ingredient.icon,
    category: ingredient.category,
    subcategory: ingredient.subcategory,
    allergens: ingredient.allergies.map(({ allergy }) => ({
      id: allergy.id,
      key: allergy.category.key,
      kind: allergy.category.kind,
    })),
    diets: ingredient.diets.map(({ diet }) => ({ id: diet.id, key: diet.key })),
  };
}

function toDietView(diet: { id: number; key: string }): DietView {
  return { id: diet.id, key: diet.key };
}

/** Deduplicates allergens (by id) across every ingredient of a recipe, for the aggregated "contains" badge — see {@link RecipeSummaryView.allergens}. */
function aggregateAllergens(ingredients: IngredientView[]): AllergyView[] {
  const byId = new Map<number, AllergyView>();
  for (const ingredient of ingredients) {
    for (const allergen of ingredient.allergens) {
      byId.set(allergen.id, allergen);
    }
  }
  return [...byId.values()];
}

/** Shapes a Prisma `Recipe` (with {@link recipeInclude} included) into the lighter {@link RecipeSummaryView} used by the catalog table — everything `toRecipeView` also needs, factored out since the full detail view is a strict superset. */
function toRecipeSummaryView(recipe: RecipeWithDetails): RecipeSummaryView {
  const allergens = aggregateAllergens(
    recipe.ingredients.map((recipeIngredient) => toIngredientView(recipeIngredient.ingredient)),
  );
  return {
    id: recipe.id,
    name: recipe.name,
    description: recipe.description,
    picture: recipe.picture,
    authorId: recipe.authorId,
    visibility: recipe.visibility,
    allergens,
    diets: recipe.diets.map((recipeDiet) => toDietView(recipeDiet.diet)),
    isFavorite: recipe.favoritedBy.length > 0,
  };
}

/** Shapes a Prisma `Recipe` (with {@link recipeInclude} included) into the public {@link RecipeView}. */
function toRecipeView(recipe: RecipeWithDetails): RecipeView {
  const ingredients = recipe.ingredients.map((recipeIngredient) => ({
    ingredient: toIngredientView(recipeIngredient.ingredient),
    quantity: Number(recipeIngredient.quantity),
    unit: recipeIngredient.unit,
  }));
  return {
    ...toRecipeSummaryView(recipe),
    ingredients,
    steps: recipe.steps.map((step) => ({
      id: step.id,
      description: step.description,
      picture: step.picture,
      order: step.order,
    })),
  };
}

/**
 * True if `viewerId`/`viewerHouseId` may *read* this recipe — the author
 * always can, whatever the current visibility (even a `HOUSE` recipe if
 * they've since left that household — access to your own creations never
 * regresses). Otherwise follows `visibility` as documented on
 * `RecipeVisibility` in schema.prisma.
 */
function canView(
  recipe: { authorId: number; authorHouseId: number | null; visibility: string },
  viewerId: number,
  viewerHouseId: number | null,
): boolean {
  if (recipe.authorId === viewerId) return true;
  if (recipe.visibility === "PUBLIC") return true;
  if (recipe.visibility === "HOUSE") {
    return viewerHouseId !== null && recipe.authorHouseId === viewerHouseId;
  }
  return false;
}

/** `Recipe` rows `viewerId`/`viewerHouseId` may read at all — the shared base every tab (except `perso`, which is already narrower) further restricts. Mirrors {@link canView} as a query filter. */
function visibleToViewerWhere(
  viewerId: number,
  viewerHouseId: number | null,
): Prisma.RecipeWhereInput {
  return {
    OR: [
      { authorId: viewerId },
      { visibility: "PUBLIC" },
      ...(viewerHouseId !== null
        ? [{ visibility: "HOUSE" as const, authorHouseId: viewerHouseId }]
        : []),
    ],
  };
}

/**
 * The recipes visible to `viewerId` under one catalog tab, alphabetically,
 * optionally filtered further by a case-insensitive name substring. No
 * "toutes" tab — every recipe a viewer can see falls under exactly one of
 * `perso`/`foyer`/`publique` (its own visibility); `favoris` is an
 * orthogonal, cross-cutting filter on top (and re-applies
 * {@link visibleToViewerWhere} in case access to a previously-favorited
 * recipe has since changed, e.g. leaving the house that granted it).
 */
export async function listRecipes(
  viewerId: number,
  viewerHouseId: number | null,
  tab: RecipeTab,
  search?: string,
): Promise<RecipeSummaryView[]> {
  const conditions: Prisma.RecipeWhereInput[] = [];
  if (search) {
    conditions.push({ name: { contains: search, mode: "insensitive" } });
  }

  switch (tab) {
    case "favoris":
      conditions.push({ favoritedBy: { some: { userProfileId: viewerId } } });
      conditions.push(visibleToViewerWhere(viewerId, viewerHouseId));
      break;
    case "perso":
      conditions.push({ visibility: "PERSONAL", authorId: viewerId });
      break;
    case "foyer":
      // No household — nothing can carry this viewer's authorHouseId.
      if (viewerHouseId === null) return [];
      conditions.push({ visibility: "HOUSE", authorHouseId: viewerHouseId });
      break;
    case "publique":
      conditions.push({ visibility: "PUBLIC" });
      break;
  }

  const recipes = await prisma.recipe.findMany({
    where: { AND: conditions },
    include: recipeInclude(viewerId),
    orderBy: { name: "asc" },
  });
  return recipes.map(toRecipeSummaryView);
}

/**
 * A single recipe's full detail.
 *
 * @throws {HttpError} `404 RECIPE_NOT_FOUND` if `id` doesn't match any recipe, or if it does but `viewerId` isn't allowed to see it (never `403` — a `PERSONAL`/`HOUSE` recipe belonging to someone else should look indistinguishable from a nonexistent one).
 */
export async function getRecipe(
  id: number,
  viewerId: number,
  viewerHouseId: number | null,
): Promise<RecipeView> {
  const recipe = await findRecipeOrThrow(id, viewerId);
  if (!canView(recipe, viewerId, viewerHouseId)) {
    throw new HttpError(404, ErrorCode.RECIPE_NOT_FOUND, `Recipe ${id} not found`);
  }
  return toRecipeView(recipe);
}

/**
 * Creates a recipe with its ingredients, ordered steps and diet tags in one
 * go — steps' `order` is derived from their position in `input.steps`,
 * ingredients reference existing reference `Ingredient` rows by id (see
 * `GET /reference/ingredients`; there's no way to create one here).
 * `authorId`/`authorHouseId` are fixed at creation and never change on
 * later edits (see {@link updateRecipe}).
 *
 * @throws {HttpError} `404 INGREDIENT_NOT_FOUND` if any `ingredientId` doesn't match a reference ingredient.
 * @throws {HttpError} `404 DIET_NOT_FOUND` if any `dietId` doesn't match a reference diet.
 */
export async function createRecipe(
  input: CreateRecipeInput,
  authorId: number,
  authorHouseId: number | null,
): Promise<RecipeView> {
  await assertIngredientsExist(input.ingredients.map((i) => i.ingredientId));
  await assertDietsExist(input.dietIds);

  const created = await prisma.recipe.create({
    data: {
      name: input.name,
      description: input.description ?? null,
      picture: input.picture ?? null,
      authorId,
      authorHouseId,
      visibility: input.visibility,
      ingredients: {
        create: input.ingredients.map((ingredient) => ({
          ingredientId: ingredient.ingredientId,
          quantity: ingredient.quantity,
          unit: ingredient.unit,
        })),
      },
      steps: {
        create: input.steps.map((step, index) => ({
          description: step.description,
          picture: step.picture ?? null,
          order: index,
        })),
      },
      diets: { create: input.dietIds.map((dietId) => ({ dietId })) },
    },
    include: recipeInclude(authorId),
  });
  return toRecipeView(created);
}

/**
 * Replaces a recipe's whole content — name/description/picture/visibility
 * and the complete ingredient/step/diet lists (not a partial merge: a line
 * missing from `input` is removed, same contract as `PATCH
 * /profile/allergies`). `authorId`/`authorHouseId` are untouched — editing
 * never transfers ownership.
 *
 * @throws {HttpError} `404 RECIPE_NOT_FOUND` if `id` doesn't match any recipe visible to `viewerId`.
 * @throws {HttpError} `403 NOT_RECIPE_AUTHOR` if `viewerId` isn't this recipe's author.
 * @throws {HttpError} `404 INGREDIENT_NOT_FOUND` if any `ingredientId` doesn't match a reference ingredient.
 * @throws {HttpError} `404 DIET_NOT_FOUND` if any `dietId` doesn't match a reference diet.
 */
export async function updateRecipe(
  id: number,
  input: UpdateRecipeInput,
  viewerId: number,
  viewerHouseId: number | null,
): Promise<RecipeView> {
  await assertIsAuthor(id, viewerId, viewerHouseId);
  await assertIngredientsExist(input.ingredients.map((i) => i.ingredientId));
  await assertDietsExist(input.dietIds);

  await prisma.$transaction([
    prisma.recipeIngredient.deleteMany({ where: { recipeId: id } }),
    prisma.step.deleteMany({ where: { recipeId: id } }),
    prisma.recipeDiet.deleteMany({ where: { recipeId: id } }),
    prisma.recipe.update({
      where: { id },
      data: {
        name: input.name,
        description: input.description ?? null,
        picture: input.picture ?? null,
        visibility: input.visibility,
        ingredients: {
          create: input.ingredients.map((ingredient) => ({
            ingredientId: ingredient.ingredientId,
            quantity: ingredient.quantity,
            unit: ingredient.unit,
          })),
        },
        steps: {
          create: input.steps.map((step, index) => ({
            description: step.description,
            picture: step.picture ?? null,
            order: index,
          })),
        },
        diets: { create: input.dietIds.map((dietId) => ({ dietId })) },
      },
    }),
  ]);

  return toRecipeView(await findRecipeOrThrow(id, viewerId));
}

/**
 * Deletes a recipe outright — its ingredients/steps/diet tags/favorites
 * cascade away (see `onDelete: Cascade` in schema.prisma).
 *
 * @throws {HttpError} `404 RECIPE_NOT_FOUND` if `id` doesn't match any recipe visible to `viewerId`.
 * @throws {HttpError} `403 NOT_RECIPE_AUTHOR` if `viewerId` isn't this recipe's author.
 * @throws {HttpError} `409 RECIPE_IN_USE` if the recipe is still referenced by a `PlanningItem` — `PlanningItem.recipeId` has no cascade of its own on purpose (removing a recipe shouldn't silently blow a hole in a planning), so this is surfaced as a normal, actionable conflict rather than a raw FK violation.
 */
export async function deleteRecipe(
  id: number,
  viewerId: number,
  viewerHouseId: number | null,
): Promise<void> {
  await assertIsAuthor(id, viewerId, viewerHouseId);

  const usedInPlanning = await prisma.planningItem.findFirst({ where: { recipeId: id } });
  if (usedInPlanning) {
    throw new HttpError(
      409,
      ErrorCode.RECIPE_IN_USE,
      "Recipe is still used by at least one planning item",
    );
  }

  await prisma.recipe.delete({ where: { id } });
}

/**
 * Favorites a recipe for `viewerId` — idempotent (favoriting an
 * already-favorited recipe is a no-op, not an error).
 *
 * @throws {HttpError} `404 RECIPE_NOT_FOUND` if `id` doesn't match any recipe visible to `viewerId` — favoriting something you can't see isn't a valid action.
 */
export async function addFavorite(
  id: number,
  viewerId: number,
  viewerHouseId: number | null,
): Promise<void> {
  const recipe = await findRecipeOrThrow(id, viewerId);
  if (!canView(recipe, viewerId, viewerHouseId)) {
    throw new HttpError(404, ErrorCode.RECIPE_NOT_FOUND, `Recipe ${id} not found`);
  }
  await prisma.recipeFavorite.upsert({
    where: { userProfileId_recipeId: { userProfileId: viewerId, recipeId: id } },
    update: {},
    create: { userProfileId: viewerId, recipeId: id },
  });
}

/** Unfavorites a recipe for `viewerId` — idempotent, no error if it wasn't favorited (or doesn't exist/isn't visible: unfavoriting is always safe, nothing to leak). */
export async function removeFavorite(id: number, viewerId: number): Promise<void> {
  await prisma.recipeFavorite.deleteMany({ where: { userProfileId: viewerId, recipeId: id } });
}

/** Re-fetches a recipe by id (with {@link recipeInclude}), or throws `404 RECIPE_NOT_FOUND` — the shared "load or reject" step for every recipe endpoint. Does *not* check visibility on its own — callers combine it with {@link canView} (read paths) or {@link assertIsAuthor} (write paths). */
async function findRecipeOrThrow(id: number, viewerId: number): Promise<RecipeWithDetails> {
  const recipe = await prisma.recipe.findUnique({
    where: { id },
    include: recipeInclude(viewerId),
  });
  if (!recipe) {
    throw new HttpError(404, ErrorCode.RECIPE_NOT_FOUND, `Recipe ${id} not found`);
  }
  return recipe;
}

/** Shared "load, check visible, check authored by viewer" guard for the write paths (`updateRecipe`/`deleteRecipe`). */
async function assertIsAuthor(
  id: number,
  viewerId: number,
  viewerHouseId: number | null,
): Promise<void> {
  const recipe = await findRecipeOrThrow(id, viewerId);
  if (!canView(recipe, viewerId, viewerHouseId)) {
    throw new HttpError(404, ErrorCode.RECIPE_NOT_FOUND, `Recipe ${id} not found`);
  }
  if (recipe.authorId !== viewerId) {
    throw new HttpError(403, ErrorCode.NOT_RECIPE_AUTHOR, "Only the recipe's author can do this");
  }
}

/** Throws `404 INGREDIENT_NOT_FOUND` if any of `ingredientIds` doesn't match a reference `Ingredient` row. */
async function assertIngredientsExist(ingredientIds: number[]): Promise<void> {
  const uniqueIds = [...new Set(ingredientIds)];
  const found = await prisma.ingredient.findMany({
    where: { id: { in: uniqueIds } },
    select: { id: true },
  });
  if (found.length !== uniqueIds.length) {
    const foundIds = new Set(found.map((ingredient) => ingredient.id));
    const missing = uniqueIds.filter((id) => !foundIds.has(id));
    throw new HttpError(
      404,
      ErrorCode.INGREDIENT_NOT_FOUND,
      `Ingredient(s) not found: ${missing.join(", ")}`,
    );
  }
}

/** Throws `404 DIET_NOT_FOUND` if any of `dietIds` doesn't match a reference `Diet` row. */
async function assertDietsExist(dietIds: number[]): Promise<void> {
  const uniqueIds = [...new Set(dietIds)];
  if (uniqueIds.length === 0) return;
  const found = await prisma.diet.findMany({
    where: { id: { in: uniqueIds } },
    select: { id: true },
  });
  if (found.length !== uniqueIds.length) {
    const foundIds = new Set(found.map((diet) => diet.id));
    const missing = uniqueIds.filter((id) => !foundIds.has(id));
    throw new HttpError(404, ErrorCode.DIET_NOT_FOUND, `Diet(s) not found: ${missing.join(", ")}`);
  }
}