import type {
  InventoryBomLineDto,
  InventoryBomLineInput,
  InventoryItemDetailDto,
  InventoryItemInput,
  InventoryItemStatus,
  InventoryItemSummaryDto,
  InventoryItemType,
  InventoryUnitOfMeasure,
} from "@mrp/shared/dist/inventory/types.js";

import { prisma } from "../../lib/prisma.js";

type BomLineRecord = {
  id: string;
  quantity: number;
  unitOfMeasure: string;
  notes: string;
  position: number;
  componentItem: {
    id: string;
    sku: string;
    name: string;
  };
};

type InventoryDetailRecord = {
  id: string;
  sku: string;
  name: string;
  description: string;
  type: string;
  status: string;
  unitOfMeasure: string;
  isSellable: boolean;
  isPurchasable: boolean;
  defaultCost: number | null;
  notes: string;
  createdAt: Date;
  updatedAt: Date;
  bomLines: BomLineRecord[];
};

function mapBomLine(record: BomLineRecord): InventoryBomLineDto {
  return {
    id: record.id,
    componentItemId: record.componentItem.id,
    componentSku: record.componentItem.sku,
    componentName: record.componentItem.name,
    quantity: record.quantity,
    unitOfMeasure: record.unitOfMeasure as InventoryUnitOfMeasure,
    notes: record.notes,
    position: record.position,
  };
}

function mapSummary(record: {
  id: string;
  sku: string;
  name: string;
  type: string;
  status: string;
  unitOfMeasure: string;
  isSellable: boolean;
  isPurchasable: boolean;
  updatedAt: Date;
  _count: { bomLines: number };
}): InventoryItemSummaryDto {
  return {
    id: record.id,
    sku: record.sku,
    name: record.name,
    type: record.type as InventoryItemType,
    status: record.status as InventoryItemStatus,
    unitOfMeasure: record.unitOfMeasure as InventoryUnitOfMeasure,
    isSellable: record.isSellable,
    isPurchasable: record.isPurchasable,
    bomLineCount: record._count.bomLines,
    updatedAt: record.updatedAt.toISOString(),
  };
}

function mapDetail(record: InventoryDetailRecord): InventoryItemDetailDto {
  return {
    ...mapSummary({
      id: record.id,
      sku: record.sku,
      name: record.name,
      type: record.type,
      status: record.status,
      unitOfMeasure: record.unitOfMeasure,
      isSellable: record.isSellable,
      isPurchasable: record.isPurchasable,
      updatedAt: record.updatedAt,
      _count: { bomLines: record.bomLines.length },
    }),
    description: record.description,
    defaultCost: record.defaultCost,
    notes: record.notes,
    createdAt: record.createdAt.toISOString(),
    bomLines: record.bomLines.slice().sort((a, b) => a.position - b.position).map(mapBomLine),
  };
}

interface InventoryListFilters {
  query?: string;
  status?: InventoryItemStatus;
  type?: InventoryItemType;
}

function buildWhereClause(filters: InventoryListFilters) {
  const trimmedQuery = filters.query?.trim();

  return {
    ...(filters.status ? { status: filters.status } : {}),
    ...(filters.type ? { type: filters.type } : {}),
    ...(trimmedQuery
      ? {
          OR: [
            { sku: { contains: trimmedQuery } },
            { name: { contains: trimmedQuery } },
            { description: { contains: trimmedQuery } },
          ],
        }
      : {}),
  };
}

function normalizeBomLines(bomLines: InventoryBomLineInput[]) {
  return bomLines
    .map((line, index) => ({
      componentItemId: line.componentItemId,
      quantity: line.quantity,
      unitOfMeasure: line.unitOfMeasure,
      notes: line.notes,
      position: line.position ?? (index + 1) * 10,
    }))
    .filter((line) => line.componentItemId.trim().length > 0);
}

async function validateBomLines(parentItemId: string | null, bomLines: InventoryBomLineInput[]) {
  const normalized = normalizeBomLines(bomLines);

  if (normalized.some((line) => line.quantity <= 0)) {
    return { ok: false as const, reason: "BOM line quantity must be greater than zero." };
  }

  if (parentItemId && normalized.some((line) => line.componentItemId === parentItemId)) {
    return { ok: false as const, reason: "An item cannot reference itself in its BOM." };
  }

  const componentIds = [...new Set(normalized.map((line) => line.componentItemId))];
  if (componentIds.length === 0) {
    return { ok: true as const, bomLines: normalized };
  }

  const existingComponents = await prisma.inventoryItem.findMany({
    where: {
      id: {
        in: componentIds,
      },
    },
    select: {
      id: true,
    },
  });

  if (existingComponents.length !== componentIds.length) {
    return { ok: false as const, reason: "One or more BOM components do not exist." };
  }

  return { ok: true as const, bomLines: normalized };
}

export async function listInventoryItems(filters: InventoryListFilters = {}) {
  const items = await prisma.inventoryItem.findMany({
    where: buildWhereClause(filters),
    include: {
      _count: {
        select: {
          bomLines: true,
        },
      },
    },
    orderBy: [{ sku: "asc" }],
  });

  return items.map(mapSummary);
}

export async function listInventoryItemOptions() {
  const items = await prisma.inventoryItem.findMany({
    where: {
      status: {
        not: "OBSOLETE",
      },
    },
    select: {
      id: true,
      sku: true,
      name: true,
    },
    orderBy: [{ sku: "asc" }],
  });

  return items.map((item) => ({
    id: item.id,
    sku: item.sku,
    name: item.name,
  }));
}

export async function getInventoryItemById(itemId: string) {
  const item = await prisma.inventoryItem.findUnique({
    where: { id: itemId },
    include: {
      bomLines: {
        include: {
          componentItem: {
            select: {
              id: true,
              sku: true,
              name: true,
            },
          },
        },
        orderBy: [{ position: "asc" }, { createdAt: "asc" }],
      },
    },
  });

  return item ? mapDetail(item) : null;
}

export async function createInventoryItem(payload: InventoryItemInput) {
  const validatedBom = await validateBomLines(null, payload.bomLines);
  if (!validatedBom.ok) {
    return null;
  }

  const item = await prisma.inventoryItem.create({
    data: {
      sku: payload.sku,
      name: payload.name,
      description: payload.description,
      type: payload.type,
      status: payload.status,
      unitOfMeasure: payload.unitOfMeasure,
      isSellable: payload.isSellable,
      isPurchasable: payload.isPurchasable,
      defaultCost: payload.defaultCost,
      notes: payload.notes,
      bomLines: validatedBom.bomLines.length
        ? {
            create: validatedBom.bomLines,
          }
        : undefined,
    },
    include: {
      bomLines: {
        include: {
          componentItem: {
            select: {
              id: true,
              sku: true,
              name: true,
            },
          },
        },
        orderBy: [{ position: "asc" }, { createdAt: "asc" }],
      },
    },
  });

  return mapDetail(item);
}

export async function updateInventoryItem(itemId: string, payload: InventoryItemInput) {
  const existingItem = await prisma.inventoryItem.findUnique({
    where: { id: itemId },
  });

  if (!existingItem) {
    return null;
  }

  const validatedBom = await validateBomLines(itemId, payload.bomLines);
  if (!validatedBom.ok) {
    return null;
  }

  const item = await prisma.inventoryItem.update({
    where: { id: itemId },
    data: {
      sku: payload.sku,
      name: payload.name,
      description: payload.description,
      type: payload.type,
      status: payload.status,
      unitOfMeasure: payload.unitOfMeasure,
      isSellable: payload.isSellable,
      isPurchasable: payload.isPurchasable,
      defaultCost: payload.defaultCost,
      notes: payload.notes,
      bomLines: {
        deleteMany: {},
        create: validatedBom.bomLines,
      },
    },
    include: {
      bomLines: {
        include: {
          componentItem: {
            select: {
              id: true,
              sku: true,
              name: true,
            },
          },
        },
        orderBy: [{ position: "asc" }, { createdAt: "asc" }],
      },
    },
  });

  return mapDetail(item);
}