public class ReportControllerTesting{
    
    //Generate report Based on parameter
    public void generateReport(string reportDevName)
    {
        try
        {
            List <Report> reportList = [SELECT Id,DeveloperName,Name FROM Report where DeveloperName =:reportDevName];
            if(reportList.size()>0)
            {
                String reportId = (String)reportList.get(0).get('Id');
                
                //Get Report Name
                string reportName=(String)reportList.get(0).get('Name');
                
                //get instance Url
                String instanceName = URL.getSalesforceBaseUrl().toExternalForm();
                
                string url=instanceName+'/servlet/PrintableViewDownloadServlet?isdtp=p1&reportId='+reportId;
                
                ApexPages.PageReference objPage = new ApexPages.PageReference(url);
                Messaging.SingleEmailMessage email=new Messaging.SingleEmailMessage();
                
                Messaging.EmailFileAttachment objMsgEmailAttach = new Messaging.EmailFileAttachment();
                objMsgEmailAttach.setFileName(reportName+'.csv');
                objMsgEmailAttach.setBody(objPage.getContent());
                objMsgEmailAttach.setContentType('text/csv');
                email.setSubject(reportName);
                
                List<Messaging.EmailFileAttachment> attach=new List<Messaging.EmailFileAttachment>();
                attach.add(objMsgEmailAttach);
                email.setFileAttachments(attach);  
                
                EmailServiceTest service=new EmailServiceTest(email);
                service.body='Hello, <br/><br/> Here is attached '+reportName+'.<br/><br/>Thank You.<br/>Admin';
                service.isHtml=true;
                service.toAddresses=new List<string>();
                service.toAddresses.add('karimulla.shamim@gmail.com');
                service.toAddresses.add('syed.karimulla@techrbm.com');
                service.displayName='Salesforce Codex';
                service.subject=reportName;
                service.sendMail();
            }
        }
        catch(Exception ex)
        {
            system.debug(ex.getMessage());
        }
    }
  
}

public class EmailServiceTest {
   public string subject{get;set;} // mail subject
    public List<String> toAddresses{get;set;} // send to
    public List<String> CCAddresses{get;set;} // cc 
    public String body{set;get;} // mail plain body
    public string displayName{set;get;} // from 
    public boolean isAttachment {set;get;} // if we have to send attachment file in mail
    public Map<String,String> attachFiles {set;get;} // key = attachmentName and value =attachmentBody 
    public boolean isHtml{set;get;}
    public List<Messaging.EmailFileAttachment> attachments; 
    public Messaging.SingleEmailMessage email;
    
    public EmailServiceTest(){
        attachments = new List<Messaging.EmailFileAttachment>();
        email =new Messaging.SingleEmailMessage();
        this.isAttachment=false;  
        this.isHtml=false;
    }
    public EmailServiceTest(Messaging.SingleEmailMessage mailMessage){
        attachments = new List<Messaging.EmailFileAttachment>();
        email =mailMessage;
        this.isAttachment=false;  
    }
    public void sendMail(){
        
        if(isAttachment){
            for (String name : attachFiles.keySet()){                
                Messaging.EmailFileAttachment csvAttc = new Messaging.EmailFileAttachment();
                blob csvBlob = Blob.valueOf(attachFiles.get(name));
                string csvname=name+'.csv';
                csvAttc.setContentType('text/csv');
                csvAttc.setFileName(csvname);
                csvAttc.setBody(csvBlob);
                attachments.add(csvAttc);
            } 
        }
        email.setSubject(subject);
        email.setToAddresses(toAddresses);
        email.setSenderDisplayName(displayName);
        if(isHtml)
        {
            email.setHtmlBody(body);
        }
        else
        {
            email.setPlainTextBody(body);
        }
        if(isAttachment){
            email.setFileAttachments(attachments);  
        }
        Messaging.SendEmailResult [] r = Messaging.sendEmail(new Messaging.SingleEmailMessage[] {email}); 
        system.debug('Email sent');
    }
}