public with sharing class BidAnnounceIframeController {
    private String recordId;
    public String iframe { get; private set; }
    
    public BidAnnounceIframeController(ApexPages.StandardController stdController) {
        recordId = stdController.getId();
    }
    
    public void init() {
        Bid_Announcement__c bid = [select Id, Web_URL__c, Web_URL_ModifiedDate__c from Bid_Announcement__c where Id = :recordId];
        List<Attachment> attList = [select Id, LastModifiedDate from Attachment where ParentId = :recordId order by LastModifiedDate desc limit 1];
        Attachment att = null;
        if (attList.size() > 0) {
            att = attList[0];
        }
        
        if (bid.Web_URL__c != null) {
            // 中标通知书URL更新时间　と　最新Attachmentの時間と比較、新しいものを適用
            if (att != null) {
                if (bid.Web_URL_ModifiedDate__c < att.LastModifiedDate) {
                    iframe = '/servlet/servlet.FileDownload?file=' + att.Id;
                } else {
                    iframe = bid.Web_URL__c;
                }
            }
            // 中标通知书URLを適用
            else {
                iframe = bid.Web_URL__c;
            }
        } else {
            // Attachmentを適用
            if (att != null) {
                iframe = '/servlet/servlet.FileDownload?file=' + att.Id;
            }
        }
    }
}