@RestResource(urlMapping='/myCaseHistoryList/*')
global with sharing class myCaseHistoryList {
    @HttpGet
    global static requestDetailsWrapper getCasesHistory(){
        
        RestRequest request = RestContext.request;    
        System.debug('===> requestURI'+request.requestURI);
        String currentcaseId = request.requestURI.substring(
            request.requestURI.lastIndexOf('/')+1);       
        system.debug('currentcaseId'+currentcaseId);
        
        Set<Id> currentcaseIds = new Set<Id>();    
        for (Case cc : [select Id from case where casenumber =: currentcaseId])
        {         
            currentcaseIds.add(cc.id); 
        } 
        Set<String> FieldValue = new Set<String>();  
        List<XcelerateCaseHistFields__c> Testi =  XcelerateCaseHistFields__c.getAll().values();
        for(XcelerateCaseHistFields__c NewField : Testi)
        {  
            FieldValue.add(NewField.Name);
        }
        system.debug('FieldValue'+FieldValue);
        Map<String, XcelerateCaseHistFields__c> allstates = XcelerateCaseHistFields__c.getAll();
        system.debug('currentcaseIds'+currentcaseIds);
        List<CaseHistory> caseList = [select Field, NewValue, createdby.Name, CreatedDate from CaseHistory
                                      where CaseId =: currentcaseIds and Field =:FieldValue order by Field,CreatedDate DESC];
        system.debug('caseList'+caseList);
        requestDetailsWrapper reqDelRap       = new requestDetailsWrapper();
        List<caseHistoryWrapper> caseHistory  = new List<caseHistoryWrapper>();
        
        for(CaseHistory a : caseList)
        {   
            CaseHistoryWrapper caseHistWrap = new CaseHistoryWrapper();
            caseHistWrap.Field              = allstates.get(a.Field).XcelerateFields__c;
            String NewValues                =  String.valueOf(a.NewValue);
            System.debug('NewValues'+NewValues);
            System.debug('a.Field'+a.Field);
            
            if (String.isBlank(NewValues) || NewValues.startsWithIgnoreCase('012') && a.Field == 'RecordType')
            {          
                continue;
            }
            Else
            {
                caseHistWrap.NewValue       = NewValues;
            }
            
            caseHistWrap.ChangedbyUser      = a.createdby.Name;
            caseHistWrap.ChangedDate        = a.CreatedDate;
            caseHistory.add(caseHistWrap);
        }
        
        List<CaseComment> commentList =  [SELECT CommentBody,CreatedBy.Name,CreatedDate FROM CaseComment where ParentId =: currentcaseIds order by CreatedDate DESC];
        
        for(CaseComment cc : commentList)
        {        
            caseHistoryWrapper commentWrap   = new caseHistoryWrapper();
            commentWrap.NewValue             = cc.CommentBody;
            commentWrap.Field                = 'Comment';
            commentWrap.ChangedDate          = cc.CreatedDate;
            commentWrap.ChangedbyUser        = cc.createdby.Name;
            caseHistory.add(commentWrap);
        }
        List<ContentDocumentLink> AttachmentList;
        try
        {
            AttachmentList     = [SELECT ContentDocument.title FROM ContentDocumentLink WHERE LinkedEntityId =: currentcaseIds];
            
            system.debug('AttachmentList'+AttachmentList);
            List<attachmentWrapper> attachments = new List<attachmentWrapper>();          
            for (ContentDocumentLink attach: AttachmentList)
            {
                attachmentWrapper attachWrap = new attachmentWrapper();
                attachWrap.AttachmentName    = attach.ContentDocument.title;
                attachments.add(attachWrap);
            }
            
            reqDelRap.caseHistory  = caseHistory; 
            reqDelRap.attachments  = attachments;
        }catch(QueryException e) 
        {
            
            System.debug(e.getMessage());
        }
        return reqDelRap;
    }
    
    global class requestDetailsWrapper{
        public List<caseHistoryWrapper> caseHistory;
        public List<attachmentWrapper> attachments;  
    }
    global class caseHistoryWrapper {
        public String Field;  
        public String NewValue;
        public String ChangedbyUser;
        public DateTime ChangedDate;
        
    }
    
    global class attachmentWrapper {
        Public String AttachmentName; 
    }
}