import { BadRequestException, Inject, Injectable } from '@nestjs/common';
import {
  CUSTOMERS_REPOSITORY,
  type CreateCustomerInput,
  type CustomerBillingMode,
  type CustomerStatus,
  type CustomerSummary,
  type CustomersRepository,
  type UpdateCustomerInput
} from './customers.repository.js';

interface CreateCustomerDto {
  name?: unknown;
  contactName?: unknown;
  phone?: unknown;
  email?: unknown;
  domain?: unknown;
  status?: unknown;
  billingMode?: unknown;
  creditLimit?: unknown;
  minBalance?: unknown;
  notes?: unknown;
}

interface UpdateCustomerDto {
  name?: unknown;
  contactName?: unknown;
  phone?: unknown;
  email?: unknown;
  domain?: unknown;
  status?: unknown;
  billingMode?: unknown;
  creditLimit?: unknown;
  minBalance?: unknown;
  notes?: unknown;
}

@Injectable()
export class CustomersService {
  constructor(@Inject(CUSTOMERS_REPOSITORY) private readonly customers: CustomersRepository) {}

  list(): Promise<CustomerSummary[]> {
    return this.customers.list();
  }

  get(customerId: string): Promise<CustomerSummary> {
    return this.customers.get(customerId);
  }

  create(body: CreateCustomerDto, actorId?: string): Promise<CustomerSummary> {
    const input: CreateCustomerInput = {
      name: this.limitedString(body.name, 'name', 120),
      contactName: this.optionalString(body.contactName, 'contactName', 80),
      phone: this.optionalString(body.phone, 'phone', 32),
      email: this.optionalString(body.email, 'email', 160),
      domain: this.optionalString(body.domain, 'domain', 160),
      status: body.status === undefined ? 'ENABLED' : this.status(body.status),
      billingMode: body.billingMode === undefined ? 'PREPAID' : this.billingMode(body.billingMode),
      creditLimit: body.creditLimit === undefined ? '0.000000' : this.money(body.creditLimit, 'creditLimit'),
      minBalance: body.minBalance === undefined ? '0.000000' : this.money(body.minBalance, 'minBalance'),
      notes: this.optionalString(body.notes, 'notes', 500),
      actorId
    };

    return this.customers.create(input);
  }

  update(customerId: string, body: UpdateCustomerDto, actorId?: string): Promise<CustomerSummary> {
    const input: UpdateCustomerInput = {
      name: body.name === undefined ? undefined : this.limitedString(body.name, 'name', 120),
      contactName: body.contactName === undefined ? undefined : this.nullableString(body.contactName, 'contactName', 80),
      phone: body.phone === undefined ? undefined : this.nullableString(body.phone, 'phone', 32),
      email: body.email === undefined ? undefined : this.nullableString(body.email, 'email', 160),
      domain: body.domain === undefined ? undefined : this.nullableString(body.domain, 'domain', 160),
      status: body.status === undefined ? undefined : this.status(body.status),
      billingMode: body.billingMode === undefined ? undefined : this.billingMode(body.billingMode),
      creditLimit: body.creditLimit === undefined ? undefined : this.money(body.creditLimit, 'creditLimit'),
      minBalance: body.minBalance === undefined ? undefined : this.money(body.minBalance, 'minBalance'),
      notes: body.notes === undefined ? undefined : this.nullableString(body.notes, 'notes', 500),
      actorId
    };

    return this.customers.update(customerId, input);
  }

  enable(customerId: string, actorId?: string): Promise<CustomerSummary> {
    return this.customers.setStatus(customerId, 'ENABLED', actorId);
  }

  disable(customerId: string, actorId?: string): Promise<CustomerSummary> {
    return this.customers.setStatus(customerId, 'DISABLED', actorId);
  }

  remove(customerId: string, actorId?: string): Promise<CustomerSummary> {
    return this.customers.softDelete(customerId, actorId);
  }

  private limitedString(value: unknown, field: string, maxLength: number): string {
    if (typeof value !== 'string' || value.trim().length === 0) {
      throw new BadRequestException({ code: 'VALIDATION_ERROR', message: `${field} is required.` });
    }

    const trimmed = value.trim();
    if (trimmed.length > maxLength) {
      throw new BadRequestException({ code: 'VALIDATION_ERROR', message: `${field} is too long.` });
    }

    return trimmed;
  }

  private optionalString(value: unknown, field: string, maxLength: number): string | undefined {
    if (value === undefined) {
      return undefined;
    }

    return this.limitedString(value, field, maxLength);
  }

  private nullableString(value: unknown, field: string, maxLength: number): string | null {
    if (value === null) {
      return null;
    }

    return this.limitedString(value, field, maxLength);
  }

  private status(value: unknown): CustomerStatus {
    if (value !== 'ENABLED' && value !== 'DISABLED') {
      throw new BadRequestException({ code: 'STATUS_INVALID', message: 'Status is invalid.' });
    }

    return value;
  }

  private billingMode(value: unknown): CustomerBillingMode {
    if (value !== 'PREPAID' && value !== 'POSTPAID') {
      throw new BadRequestException({ code: 'BILLING_MODE_INVALID', message: 'Billing mode is invalid.' });
    }

    return value;
  }

  private money(value: unknown, field: string): string {
    const raw = typeof value === 'number' ? value.toString() : typeof value === 'string' ? value.trim() : '';
    if (!/^\d{1,14}(?:\.\d{1,6})?$/.test(raw)) {
      throw new BadRequestException({ code: 'MONEY_INVALID', message: `${field} must be a non-negative decimal with up to 6 places.` });
    }

    const [integerPart, fractionPart = ''] = raw.split('.');
    return `${integerPart}.${fractionPart.padEnd(6, '0')}`;
  }
}