public inherited sharing class CreateEmailToCase {
  public class Request {
    @InvocableVariable(required=true label='Routing Name')
    public String routingName;

    @InvocableVariable(required=true label='Email Address')
    public String emailAddress;

    @InvocableVariable(required=true label='Case Owner Queue Id')
    public Id caseOwnerId;

    @InvocableVariable(required=true label='Case Origin')
    public String caseOrigin;
  }

  public class Result {
    @InvocableVariable(label='Metadata Full Name')
    public String metadataFullName;

    @InvocableVariable(label='Routing Name')
    public String routingName;

    @InvocableVariable(label='Email Address')
    public String emailAddress;

    @InvocableVariable(label='Email-to-Case Address')
    public String emailToCaseAddress;

    @InvocableVariable(label='Email Routing Address Id')
    public Id emailRoutingAddressId;

    @InvocableVariable(label='Created')
    public Boolean created;
  }

  @InvocableMethod(
    label='Create Email-To-Case'
    description='Adds an on-demand Email-to-Case routing address to Case Settings.'
    category='Queue Configuration'
    callout=true
  )
  public static List<Result> createRoutingAddress(List<Request> requests) {
    MetadataXml.require(
      requests != null && requests.size() == 1,
      'Create Email-To-Case accepts exactly one request per invocation.'
    );
    Request input = requests[0];
    input.routingName = input.routingName == null
      ? null
      : input.routingName.trim();
    input.emailAddress = input.emailAddress == null
      ? null
      : input.emailAddress.trim();
    input.caseOrigin = input.caseOrigin == null
      ? null
      : input.caseOrigin.trim();
    MetadataXml.require(
      !String.isBlank(input.routingName),
      'Routing Name is required.'
    );
    MetadataXml.require(
      !String.isBlank(input.emailAddress),
      'Email Address is required.'
    );
    MetadataXml.require(
      input.caseOwnerId != null,
      'Case Owner Queue Id is required.'
    );
    MetadataXml.require(
      !String.isBlank(input.caseOrigin),
      'Case Origin is required.'
    );

    List<Group> queues = [
      SELECT Id, DeveloperName
      FROM Group
      WHERE Id = :input.caseOwnerId AND Type = 'Queue'
      WITH USER_MODE
      LIMIT 1
    ];
    MetadataXml.require(
      !queues.isEmpty(),
      'Case Owner Id must identify a queue.'
    );

    Dom.XmlNode caseSettings = MetadataApiClient.readMetadata(
      'CaseSettings',
      'Case'
    );
    MetadataXml.require(
      caseSettings != null,
      'Case Settings metadata was not found.'
    );
    Dom.XmlNode emailToCase = MetadataXml.child(caseSettings, 'emailToCase');
    MetadataXml.require(
      emailToCase != null,
      'Email-to-Case is not configured. Enable Email-to-Case in Setup before creating a routing address.'
    );

    for (
      Dom.XmlNode route : MetadataXml.children(emailToCase, 'routingAddresses')
    ) {
      String existingName = MetadataXml.text(route, 'routingName');
      String existingAddress = MetadataXml.text(route, 'emailAddress');
      Boolean sameName = input.routingName.equalsIgnoreCase(existingName);
      Boolean sameAddress = input.emailAddress.equalsIgnoreCase(
        existingAddress
      );
      if (sameName || sameAddress) {
        MetadataXml.require(
          sameName && sameAddress,
          'An Email-to-Case routing address already uses this routing name or email address with different values.'
        );
        return new List<Result>{ buildResult(input, false) };
      }
    }

    String routeXml =
      '<routingAddresses>' +
      '<addressType>EmailToCase</addressType>' +
      '<caseOrigin>' +
      MetadataXml.escape(input.caseOrigin) +
      '</caseOrigin>' +
      '<caseOwner>' +
      MetadataXml.escape(queues[0].DeveloperName) +
      '</caseOwner>' +
      '<caseOwnerType>Queue</caseOwnerType>' +
      '<casePriority>Medium</casePriority>' +
      '<emailAddress>' +
      MetadataXml.escape(input.emailAddress) +
      '</emailAddress>' +
      '<routingName>' +
      MetadataXml.escape(input.routingName) +
      '</routingName>' +
      '<saveEmailHeaders>false</saveEmailHeaders>' +
      '</routingAddresses>';
    String emailToCaseXml = '<emailToCase>';
    Boolean inserted = false;
    for (Dom.XmlNode child : emailToCase.getChildElements()) {
      if (!inserted && child.getName().compareTo('routingAddresses') > 0) {
        emailToCaseXml += routeXml;
        inserted = true;
      }
      emailToCaseXml += MetadataXml.serialize(child);
    }
    if (!inserted) {
      emailToCaseXml += routeXml;
    }
    emailToCaseXml += '</emailToCase>';

    MetadataApiClient.updateMetadata(
      'CaseSettings',
      MetadataXml.replaceOrInsertChild(
        caseSettings,
        'emailToCase',
        emailToCaseXml
      )
    );
    return new List<Result>{ buildResult(input, true) };
  }

  private static Result buildResult(Request input, Boolean created) {
    Result result = new Result();
    result.metadataFullName = 'Case';
    result.routingName = input.routingName;
    result.emailAddress = input.emailAddress;
    result.created = created;

    Schema.SObjectType routingType = Schema.getGlobalDescribe()
      .get('EmailRoutingAddress');
    if (routingType == null) {
      return result;
    }
    Map<String, Schema.SObjectField> fields = routingType.getDescribe()
      .fields.getMap();
    String addressField = fields.containsKey('EmailAddress')
      ? 'EmailAddress'
      : (fields.containsKey('Address') ? 'Address' : null);
    if (addressField == null) {
      return result;
    }

    List<String> selectFields = new List<String>{ 'Id', addressField };
    if (fields.containsKey('RoutingAddress')) {
      selectFields.add('RoutingAddress');
    }
    if (fields.containsKey('EmailServicesAddressId')) {
      selectFields.add('EmailServicesAddressId');
    }
    String query =
      'SELECT ' +
      String.join(selectFields, ',') +
      ' FROM EmailRoutingAddress WHERE ' +
      addressField +
      ' = :emailAddress LIMIT 1';
    List<SObject> matches = Database.queryWithBinds(
      query,
      new Map<String, Object>{ 'emailAddress' => input.emailAddress },
      AccessLevel.USER_MODE
    );
    if (matches.isEmpty()) {
      return result;
    }

    result.emailRoutingAddressId = (Id) matches[0].get('Id');
    if (fields.containsKey('RoutingAddress')) {
      result.emailToCaseAddress = (String) matches[0].get('RoutingAddress');
    } else if (fields.containsKey('EmailServicesAddressId')) {
      result.emailToCaseAddress = emailServicesAddress(
        (Id) matches[0].get('EmailServicesAddressId')
      );
    }
    return result;
  }

  private static String emailServicesAddress(Id serviceAddressId) {
    if (serviceAddressId == null) {
      return null;
    }
    Schema.SObjectType serviceType = Schema.getGlobalDescribe()
      .get('EmailServicesAddress');
    if (serviceType == null) {
      return null;
    }
    Map<String, Schema.SObjectField> fields = serviceType.getDescribe()
      .fields.getMap();
    if (
      !fields.containsKey('LocalPart') || !fields.containsKey('EmailDomainName')
    ) {
      return null;
    }
    List<SObject> rows = Database.queryWithBinds(
      'SELECT LocalPart, EmailDomainName FROM EmailServicesAddress WHERE Id = :serviceAddressId LIMIT 1',
      new Map<String, Object>{ 'serviceAddressId' => serviceAddressId },
      AccessLevel.USER_MODE
    );
    return rows.isEmpty()
      ? null
      : String.valueOf(rows[0].get('LocalPart')) +
        '@' +
        String.valueOf(rows[0].get('EmailDomainName'));
  }
}