import { and, eq, ilike, or, sql } from 'drizzle-orm';
import { db } from '@/lib/db';
import { companies, companyTags } from '@/lib/db/schema/companies';
import type { Company } from '@/lib/db/schema/companies';
import { withTransaction } from '@/lib/db/utils';
import { buildListQuery } from '@/lib/db/query-builder';
import { createAuditLog } from '@/lib/audit';
import { NotFoundError, ConflictError } from '@/lib/errors';
import { emitToRoom } from '@/lib/socket/server';
import { diffEntity } from '@/lib/entity-diff';
import type { z } from 'zod';
import type {
  createCompanySchema,
  UpdateCompanyInput,
  ListCompaniesInput,
} from '@/lib/validators/companies';

type CreateCompanyInput = z.input<typeof createCompanySchema>;

interface AuditMeta {
  userId: string;
  portId: string;
  ipAddress: string;
  userAgent: string;
}

export type { Company };

// ─── Helpers ─────────────────────────────────────────────────────────────────

/**
 * Returns true if the error is a Postgres unique-violation (SQLSTATE 23505).
 * We check a few shapes because the exact object depends on the driver.
 */
function isUniqueViolation(err: unknown): boolean {
  if (!err || typeof err !== 'object') return false;
  const e = err as { code?: unknown; cause?: { code?: unknown } };
  if (e.code === '23505') return true;
  if (e.cause && typeof e.cause === 'object' && e.cause.code === '23505') return true;
  return false;
}

// ─── Create ──────────────────────────────────────────────────────────────────

export async function createCompany(portId: string, data: CreateCompanyInput, meta: AuditMeta) {
  // Pre-check (case-insensitive) for friendlier ConflictError; the partial unique
  // index `idx_companies_name_unique ON companies(portId, lower(name))` is the
  // authoritative guard and caught below as defense-in-depth.
  const existing = await db.query.companies.findFirst({
    where: and(eq(companies.portId, portId), sql`lower(${companies.name}) = lower(${data.name})`),
  });
  if (existing) {
    throw new ConflictError('company name already exists');
  }

  try {
    return await withTransaction(async (tx) => {
      const [company] = await tx
        .insert(companies)
        .values({
          portId,
          name: data.name,
          legalName: data.legalName ?? null,
          taxId: data.taxId ?? null,
          registrationNumber: data.registrationNumber ?? null,
          incorporationCountry: data.incorporationCountry ?? null,
          incorporationDate: data.incorporationDate ?? null,
          status: data.status ?? 'active',
          billingEmail: data.billingEmail ?? null,
          notes: data.notes ?? null,
        })
        .returning();

      const tagIds = data.tagIds ?? [];
      if (tagIds.length > 0) {
        await tx
          .insert(companyTags)
          .values(tagIds.map((tagId) => ({ companyId: company!.id, tagId })));
      }

      void createAuditLog({
        userId: meta.userId,
        portId,
        action: 'create',
        entityType: 'company',
        entityId: company!.id,
        newValue: { name: company!.name, status: company!.status },
        ipAddress: meta.ipAddress,
        userAgent: meta.userAgent,
      });

      emitToRoom(`port:${portId}`, 'company:created', { companyId: company!.id });

      return company!;
    });
  } catch (err) {
    if (isUniqueViolation(err)) {
      throw new ConflictError('company name already exists');
    }
    throw err;
  }
}

// ─── Get ─────────────────────────────────────────────────────────────────────

export async function getCompanyById(id: string, portId: string) {
  const company = await db.query.companies.findFirst({
    where: and(eq(companies.id, id), eq(companies.portId, portId)),
  });
  if (!company) throw new NotFoundError('Company');
  return company;
}

// ─── Update ──────────────────────────────────────────────────────────────────

export async function updateCompany(
  id: string,
  portId: string,
  data: UpdateCompanyInput,
  meta: AuditMeta,
) {
  const existing = await db.query.companies.findFirst({
    where: eq(companies.id, id),
  });

  if (!existing || existing.portId !== portId) {
    throw new NotFoundError('Company');
  }

  const { diff } = diffEntity(
    existing as unknown as Record<string, unknown>,
    data as Record<string, unknown>,
  );

  let updated: Company | undefined;
  try {
    const rows = await db
      .update(companies)
      .set({ ...data, updatedAt: new Date() })
      .where(and(eq(companies.id, id), eq(companies.portId, portId)))
      .returning();
    updated = rows[0];
  } catch (err) {
    if (isUniqueViolation(err)) {
      throw new ConflictError('company name already exists');
    }
    throw err;
  }

  void createAuditLog({
    userId: meta.userId,
    portId,
    action: 'update',
    entityType: 'company',
    entityId: id,
    oldValue: diff as Record<string, unknown>,
    newValue: data as Record<string, unknown>,
    ipAddress: meta.ipAddress,
    userAgent: meta.userAgent,
  });

  emitToRoom(`port:${portId}`, 'company:updated', {
    companyId: id,
    changedFields: Object.keys(diff),
  });

  return updated!;
}

// ─── Archive ─────────────────────────────────────────────────────────────────

export async function archiveCompany(id: string, portId: string, meta: AuditMeta) {
  const existing = await db.query.companies.findFirst({
    where: eq(companies.id, id),
  });

  if (!existing || existing.portId !== portId) {
    throw new NotFoundError('Company');
  }

  // NOTE: bypassing the shared `softDelete(...)` util: it sets the raw column key
  // `archived_at`, which Drizzle does not recognise (the JS key is `archivedAt`)
  // and therefore emits an empty SET clause. Until the utility is fixed, do the
  // update inline. (See Task 2.3 for context.)
  await db
    .update(companies)
    .set({ archivedAt: new Date() })
    .where(and(eq(companies.id, id), eq(companies.portId, portId)));

  void createAuditLog({
    userId: meta.userId,
    portId,
    action: 'archive',
    entityType: 'company',
    entityId: id,
    ipAddress: meta.ipAddress,
    userAgent: meta.userAgent,
  });

  emitToRoom(`port:${portId}`, 'company:archived', { companyId: id });
}

// ─── List ────────────────────────────────────────────────────────────────────

export async function listCompanies(portId: string, query: ListCompaniesInput) {
  const { page, limit, sort, order, search, includeArchived, status } = query;

  const filters = [];
  if (status) filters.push(eq(companies.status, status));

  let sortColumn: typeof companies.name | typeof companies.createdAt | typeof companies.updatedAt =
    companies.updatedAt;
  if (sort === 'name') sortColumn = companies.name;
  else if (sort === 'createdAt') sortColumn = companies.createdAt;

  const result = await buildListQuery<Company>({
    table: companies,
    portIdColumn: companies.portId,
    portId,
    idColumn: companies.id,
    updatedAtColumn: companies.updatedAt,
    searchColumns: [companies.name, companies.legalName, companies.taxId],
    searchTerm: search,
    filters,
    sort: sort ? { column: sortColumn, direction: order } : undefined,
    page,
    pageSize: limit,
    includeArchived,
    archivedAtColumn: companies.archivedAt,
  });

  return result;
}

// ─── Autocomplete ────────────────────────────────────────────────────────────

export async function autocomplete(portId: string, q: string) {
  const pattern = `%${q}%`;
  return await db
    .select()
    .from(companies)
    .where(
      and(
        eq(companies.portId, portId),
        or(ilike(companies.name, pattern), ilike(companies.legalName, pattern)),
      ),
    )
    .limit(10);
}

// ─── Upsert by name (find-or-create) ─────────────────────────────────────────

/**
 * Find-or-create a company by (portId, lower(name)). NOT a Postgres UPSERT.
 *
 * Runs a case-insensitive SELECT scoped by portId; if found, returns it.
 * Otherwise inserts a new row with the provided `name` verbatim. A concurrent
 * insert that hits the partial unique index (23505) is re-raised as
 * ConflictError for the caller to retry if desired.
 */
export async function upsertByName(portId: string, name: string, meta: AuditMeta) {
  return await withTransaction(async (tx) => {
    const existing = await tx.query.companies.findFirst({
      where: and(eq(companies.portId, portId), sql`lower(${companies.name}) = lower(${name})`),
    });
    if (existing) return existing;

    try {
      const [company] = await tx
        .insert(companies)
        .values({
          portId,
          name,
          status: 'active',
        })
        .returning();

      void createAuditLog({
        userId: meta.userId,
        portId,
        action: 'create',
        entityType: 'company',
        entityId: company!.id,
        newValue: { name: company!.name, status: company!.status },
        ipAddress: meta.ipAddress,
        userAgent: meta.userAgent,
      });

      emitToRoom(`port:${portId}`, 'company:created', { companyId: company!.id });

      return company!;
    } catch (err) {
      if (isUniqueViolation(err)) {
        throw new ConflictError('company name already exists');
      }
      throw err;
    }
  });
}