import { ForbiddenException, Injectable, Logger, NotFoundException } from '@nestjs/common';
import { Prisma } from '@prisma/client';
import * as fs from 'node:fs/promises';
import * as path from 'node:path';
import { PrismaService } from '../prisma/prisma.service';
import { CreateRecipeDto } from './dto/create-recipe.dto';
import { ParseMarkdownDto } from './dto/parse-markdown.dto';
import { downloadAndOptimizeImage } from '../common/utils/download-image';
import { parseRecipeMarkdown } from '../common/utils/recipe-parser';
import { normalizeUnit, getUnitType, convertUnit, canConvert } from '../common/utils/units';

const IMAGE_DEST_DIR = process.env.IMAGE_DEST_DIR || '/app/recipe-images';

@Injectable()
export class RecipesService {
  private readonly logger = new Logger(RecipesService.name);

  constructor(private readonly prisma: PrismaService) {}

  private throwRecipeNotFound(id: number): never {
    throw new NotFoundException(`Recipe with id ${id} not found`);
  }

  private async findRecipeByIdOrThrow(id: number) {
    const recipe = await this.prisma.recipe.findUnique({ where: { id } });
    if (!recipe) {
      this.throwRecipeNotFound(id);
    }
    return recipe;
  }

  private assertRecipeEditableByUser(recipe: { ownerId: number | null }, userId: number, id: number) {
    // Legacy behavior: ownerless recipes are editable to preserve existing semantics.
    if (recipe.ownerId !== null && recipe.ownerId !== userId) {
      this.throwRecipeNotFound(id);
    }
  }

  private assertRecipeOwnedByUser(recipe: { ownerId: number | null }, userId: number, id: number) {
    if (recipe.ownerId !== userId) {
      this.throwRecipeNotFound(id);
    }
  }

  async getInventoryPreview(id: number, userId: number) {
    const recipe = await this.prisma.recipe.findFirst({
      where: {
        id,
        OR: [
          { isPublic: true },
          { ownerId: userId },
          { shares: { some: { userId } } },
        ],
      },
      include: {
        ingredients: {
          include: {
            product: true,
          },
          orderBy: {
            id: 'asc',
          },
        },
      },
    });

    if (!recipe) {
      throw new NotFoundException(`Recipe with id ${id} not found`);
    }

    const ingredientPreviews = await Promise.all(
      recipe.ingredients.map(async (ingredient: any) => {
        const inventoryItems = await this.prisma.inventoryItem.findMany({
          where: { productId: ingredient.productId },
          orderBy: { createdAt: 'desc' },
        });

        // Hitta inventory-poster med samma enhet
        const sameUnitItems = inventoryItems.filter(
          (item: any) => item.unit.trim().toLowerCase() === ingredient.unit.trim().toLowerCase(),
        );
        const availableSameUnit = sameUnitItems.reduce(
          (sum: number, item: any) => sum + Number(item.quantity),
          0,
        );

        // Hitta inventory-poster med annan enhet och konvertera (endast viktbaserade enheter)
        const otherUnitItems = inventoryItems.filter(
          (item: any) => item.unit.trim().toLowerCase() !== ingredient.unit.trim().toLowerCase(),
        );
        let availableOtherUnit = 0;

        for (const item of otherUnitItems) {
          // Konvertera endast om enheter är kompatibla (samma kategori)
          try {
            const convertedQuantity = convertUnit(
              Number(item.quantity),
              item.unit,
              ingredient.unit,
            );
            availableOtherUnit += convertedQuantity;
          } catch {
            // Om konvertering misslyckas, hoppa över denna post
            // (t.ex. st kan inte konverteras till g)
          }
        }

        const totalAvailable = availableSameUnit + availableOtherUnit;
        let status: 'enough' | 'missing' | 'unit_mismatch';

        if (totalAvailable >= Number(ingredient.quantity)) {
          status = 'enough';
        } else if (availableSameUnit === 0 && availableOtherUnit > 0) {
          status = 'unit_mismatch';
        } else {
          status = 'missing';
        }

        return {
          ingredientId: ingredient.id,
          productId: ingredient.productId,
          productName: ingredient.product.canonicalName || ingredient.product.name,
          requiredQuantity: Number(ingredient.quantity),
          requiredUnit: ingredient.unit,
          note: ingredient.note,
          availableQuantity: totalAvailable,
          availableUnit: ingredient.unit,
          matchingInventoryItems: sameUnitItems.map((item: any) => ({
            id: item.id,
            quantity: item.quantity,
            unit: item.unit,
            location: item.location,
            brand: item.brand || null,
            bestBeforeDate: item.bestBeforeDate || null,
          })),
          otherInventoryItems: otherUnitItems.map((item: any) => {
              // Kolla om konvertering är möjlig (samma enhetskategori)
            const canConvertUnits = canConvert(item.unit, ingredient.unit);
            let convertedQuantity = 0;
            if (canConvertUnits) {
              try {
                convertedQuantity = convertUnit(Number(item.quantity), item.unit, ingredient.unit);
              } catch {
                convertedQuantity = 0;
              }
            }

            return {
              id: item.id,
              quantity: item.quantity,
              unit: item.unit,
              location: item.location,
              convertedQuantity: canConvertUnits ? convertedQuantity : 0,
              canConvert: canConvertUnits,
            };
          }),
          status,
          missingQuantity: status === 'missing' ? Math.max(0, Number(ingredient.quantity) - totalAvailable) : 0,
        };
      }),
    );

    const summary = {
      totalIngredients: ingredientPreviews.length,
      enoughCount: ingredientPreviews.filter((i: any) => i.status === 'enough').length,
      missingCount: ingredientPreviews.filter((i: any) => i.status === 'missing').length,
      unitMismatchCount: ingredientPreviews.filter((i: any) => i.status === 'unit_mismatch').length,
      canCookExactly: ingredientPreviews.every((i: any) => i.status === 'enough'),
    };

    return {
      recipe: {
        id: recipe.id,
        name: recipe.name,
        description: recipe.description,
      },
      ingredients: ingredientPreviews,
      summary,
    };
  }

  async findAll(userId: number) {
    return this.prisma.recipe.findMany({
      where: {
        OR: [
          { isPublic: true },
          { ownerId: userId },
          { shares: { some: { userId } } },
        ],
      },
      include: {
        ingredients: {
          include: {
            product: { include: { nutrition: true } },
          },
        },
        owner: { select: { id: true, username: true } },
        shares: { select: { userId: true } },
      },
    });
  }

  async findOne(id: number, userId: number) {
    const recipe = await this.prisma.recipe.findFirst({
      where: {
        id,
        OR: [
          { isPublic: true },
          { ownerId: userId },
          { shares: { some: { userId } } },
        ],
      },
      include: {
        ingredients: {
          include: {
            product: { include: { nutrition: true } },
          },
        },
        owner: { select: { id: true, username: true } },
        shares: { select: { userId: true } },
      },
    });

    if (!recipe) {
      throw new NotFoundException(`Recipe with id ${id} not found`);
    }

    return recipe;
  }

  async update(id: number, updateRecipeDto: CreateRecipeDto, userId: number) {
    const existingRecipe = await this.findRecipeByIdOrThrow(id);
    this.assertRecipeEditableByUser(existingRecipe, userId, id);

    // Ta bort gamla ingredienser
    await this.prisma.recipeIngredient.deleteMany({
      where: { recipeId: id },
    });

    // Uppdatera receptet och lägg till nya ingredienser
    const recipe = await this.prisma.recipe.update({
      where: { id },
      data: {
        name: updateRecipeDto.name,
        description: updateRecipeDto.description || null,
        instructions: updateRecipeDto.instructions || null,
        servings: updateRecipeDto.servings ?? null,
        ...(updateRecipeDto.isPublic !== undefined && { isPublic: updateRecipeDto.isPublic }),
        ...(updateRecipeDto.imageUrl !== undefined && { imageUrl: updateRecipeDto.imageUrl || null }),
        ingredients: {
          create: updateRecipeDto.ingredients.map((ingredient) => ({
            productId: ingredient.productId,
            quantity: ingredient.quantity,
            unit: ingredient.unit,
            note: ingredient.note || null,
          })),
        },
      },
      include: {
        ingredients: {
          include: {
            product: { include: { nutrition: true } },
          },
        },
      },
    });

    return recipe;
  }

  async remove(id: number, userId: number) {
    const existingRecipe = await this.findRecipeByIdOrThrow(id);
    this.assertRecipeEditableByUser(existingRecipe, userId, id);

    await this.prisma.recipeIngredient.deleteMany({ where: { recipeId: id } });
    await this.prisma.recipe.delete({ where: { id } });

    // Radera lokal bildfil om den finns (undviker orphan-filer på disk).
    if (existingRecipe.imageUrl?.startsWith('/images/')) {
      const filename = path.basename(existingRecipe.imageUrl);
      const filePath = path.join(IMAGE_DEST_DIR, filename);
      await fs.unlink(filePath).catch(() => {
        // Filen kanske redan är borttagen — ignorera felet.
      });
    }
  }

  async updateImage(id: number, sourceUrl: string, userId: number) {
    const existingRecipe = await this.findRecipeByIdOrThrow(id);
    this.assertRecipeOwnedByUser(existingRecipe, userId, id);

    const imageUrl = await downloadAndOptimizeImage(sourceUrl, IMAGE_DEST_DIR);

    return this.prisma.recipe.update({
      where: { id },
      data: { imageUrl },
      include: {
        ingredients: { include: { product: { include: { nutrition: true } } } },
        owner: { select: { id: true, username: true } },
        shares: { select: { userId: true } },
      },
    });
  }

  async setVisibility(id: number, userId: number, isPublic: boolean) {
    const existingRecipe = await this.findRecipeByIdOrThrow(id);
    this.assertRecipeOwnedByUser(existingRecipe, userId, id);

    if (isPublic) {
      const owner = await this.prisma.user.findUnique({
        where: { id: userId },
        select: { canShareRecipes: true },
      });
      if (!owner?.canShareRecipes) {
        throw new ForbiddenException('Du har inte behörighet att dela recept.');
      }
    }

    return this.prisma.recipe.update({
      where: { id },
      data: { isPublic },
      include: {
        ingredients: { include: { product: { include: { nutrition: true } } } },
        owner: { select: { id: true, username: true } },
        shares: { select: { userId: true } },
      },
    });
  }

  async shareWithUser(id: number, ownerId: number, username: string) {
    const recipe = await this.findRecipeByIdOrThrow(id);
    this.assertRecipeOwnedByUser(recipe, ownerId, id);

    const owner = await this.prisma.user.findUnique({
      where: { id: ownerId },
      select: { canShareRecipes: true },
    });
    if (!owner?.canShareRecipes) {
      throw new ForbiddenException('Du har inte behörighet att dela recept.');
    }

    const targetUser = await this.prisma.user.findUnique({
      where: { username },
      select: { id: true },
    });
    if (!targetUser) {
      throw new NotFoundException(`User ${username} not found`);
    }
    if (targetUser.id === ownerId) {
      return this.findOne(id, ownerId);
    }

    await this.prisma.recipeShare.upsert({
      where: { recipeId_userId: { recipeId: id, userId: targetUser.id } },
      create: { recipeId: id, userId: targetUser.id },
      update: {},
    });

    return this.findOne(id, ownerId);
  }

  async unshareWithUser(id: number, ownerId: number, username: string) {
    const recipe = await this.findRecipeByIdOrThrow(id);
    this.assertRecipeOwnedByUser(recipe, ownerId, id);

    const targetUser = await this.prisma.user.findUnique({
      where: { username },
      select: { id: true },
    });
    if (!targetUser) {
      throw new NotFoundException(`User ${username} not found`);
    }

    await this.prisma.recipeShare.deleteMany({
      where: { recipeId: id, userId: targetUser.id },
    });

    return this.findOne(id, ownerId);
  }

  async create(createRecipeDto: CreateRecipeDto, userId: number) {
    this.logger.log(
      `[create] Incoming imageUrl from client: ${createRecipeDto.imageUrl ?? 'null'}`,
    );

    // Om imageUrl är en extern URL — ladda ner och optimera
    let imageUrl: string | null = createRecipeDto.imageUrl || null;
    if (imageUrl && imageUrl.startsWith('http')) {
      const externalImageUrl = imageUrl;
      try {
        imageUrl = await downloadAndOptimizeImage(imageUrl, IMAGE_DEST_DIR);
      } catch (err) {
        console.warn('[RecipesService] Kunde inte ladda ner receptbild:', err);
        // Behåll extern URL som fallback så bild fortfarande visas.
        imageUrl = externalImageUrl;
      }
    }

    this.logger.log(`[create] Final imageUrl persisted to DB: ${imageUrl ?? 'null'}`);

    const recipe = await this.prisma.recipe.create({
      data: {
        name: createRecipeDto.name,
        description: createRecipeDto.description || null,
        instructions: createRecipeDto.instructions || null,
        imageUrl,
        servings: createRecipeDto.servings ?? null,
        ownerId: userId,
        isPublic: false,
        ingredients: {
          create: createRecipeDto.ingredients.map((ingredient) => ({
            productId: ingredient.productId,
            quantity: ingredient.quantity,
            unit: ingredient.unit,
            note: ingredient.note || null,
          })),
        },
      },
      include: {
        ingredients: {
          include: {
            product: { include: { nutrition: true } },
          },
        },
      },
    });

    return recipe;
  }

  async parseMarkdown(dto: ParseMarkdownDto) {
    // Delegera markdown-parsning till microservice-importer
    const importerUrl = process.env.IMPORTER_SERVICE_URL || 'http://importer-api:3001';
    let parsed: ParsedRecipe;
    try {
      const response = await fetch(`${importerUrl}/api/recipes/parse-markdown`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ markdown: dto.markdown }),
      });
      if (!response.ok) {
        throw new Error(`Importer svarade ${response.status}`);
      }
      parsed = (await response.json()) as ParsedRecipe;
    } catch (err) {
      this.logger.error(`Kunde inte nå importer-api för parse-markdown: ${err}`);
      // Fallback: använd lokal parser vid driftavbrott
      parsed = parseRecipeMarkdown(dto.markdown);
    }

    const allProducts = await this.prisma.product.findMany({
      where: { isActive: true },
      select: { id: true, name: true, canonicalName: true, normalizedName: true },
    });

    // Normalisera en sträng för jämförelse (lowercase, trim, ta bort skiljetecken)
    const normalize = (s: string) =>
      s.toLowerCase().trim().replace(/[^a-zåäö0-9\s]/gi, '').replace(/\s+/g, ' ');

    // Enkel Levenshtein-distans
    const levenshtein = (a: string, b: string): number => {
      const m = a.length;
      const n = b.length;
      const dp: number[][] = Array.from({ length: m + 1 }, (_, i) =>
        Array.from({ length: n + 1 }, (_, j) => (i === 0 ? j : j === 0 ? i : 0)),
      );
      for (let i = 1; i <= m; i++) {
        for (let j = 1; j <= n; j++) {
          dp[i][j] =
            a[i - 1] === b[j - 1]
              ? dp[i - 1][j - 1]
              : 1 + Math.min(dp[i - 1][j], dp[i][j - 1], dp[i - 1][j - 1]);
        }
      }
      return dp[m][n];
    };

    const ingredientsWithSuggestions = parsed.ingredients.map((ingredient: ParsedIngredient) => {
      const query = normalize(ingredient.rawName);

      const scored = allProducts
        .map((product) => {
          const targetName = normalize(product.canonicalName || product.name);
          const targetNormalized = normalize(product.normalizedName);

          // Exakt träff på normalizedName prioriteras
          if (targetNormalized === query || targetName === query) {
            return { product, score: 100 };
          }

          // Delsträng-match
          if (targetName.includes(query) || query.includes(targetName)) {
            return { product, score: 70 };
          }

          // Levenshtein-baserad likhet
          const dist = levenshtein(query, targetName);
          const maxLen = Math.max(query.length, targetName.length);
          const similarity = maxLen === 0 ? 100 : Math.round((1 - dist / maxLen) * 100);

          return { product, score: similarity };
        })
        .filter((s) => s.score >= 40)
        .sort((a, b) => b.score - a.score)
        .slice(0, 5)
        .map((s) => ({
          productId: s.product.id,
          productName: s.product.canonicalName || s.product.name,
          score: s.score,
        }));

      return {
        rawName: ingredient.rawName,
        quantity: ingredient.quantity,
        unit: ingredient.unit,
        note: ingredient.note,
        suggestions: scored,
      };
    });

    return {
      name: parsed.name,
      description: parsed.description,
      instructions: parsed.instructions,
      ingredients: ingredientsWithSuggestions,
    };
  }
}