//YSA le 04/12/2017
//Permets la génération de liens privés et temporaires vers l'espace donateur
//Classe de test : ALS_Generate_Tmp_Link_Test
public class ALS_Generate_Tmp_Link {

   /**
     * Returns the temporary link
     *
     * @param list      listContact
     *
     * @return void
     */
    public static void generateTmpLink(List<Contact> listContact){

        //Instance for custom settings TemporaryLink
        Temporary_link__c cs = Temporary_link__c.getInstance();
        //Get key
        String secret = cs.Encrypt_Key__c;

        //Link
        String temporaryLink;

        //get the number of seconds since january 1 1970
        DateTime dt = Datetime.now();
        Long gettimeMs = dt.getTime();
        Long gettimeS = gettimeMs / 1000;

        //Build the link
        for(Contact ctc : listContact){
            if( ! String.isBlank(ctc.Email)){

                temporaryLink     = generateTmpLinkPure(ctc.Email , ctc.id, 1513177342, secret);
                ctc.Lien_prive_et_temporaire__c = cs.URL__c + temporaryLink;
            }
        }
    }

    /**
     * Generates a temporary link containing :
     *    - the donor email
     *    - the signature of the idSF (because it must not be public)
     *    - the time : timestamp to calculate when the link must expire
     *
     * @param string    email Contact email
     * @param string    idSf SalesForce Contact Id
     * @param int       time time()
     * @param string    secret 'secret' defined in the parameters
     *
     * @return string   Temporary link
     */
    public static String generateTmpLinkPure(String email, String idSf, Long timeNow, String secret){
        System.debug('## generateTmpLinkPure email : '      + email);
        System.debug('## generateTmpLinkPure idContact : '  + idSf);
        System.debug('## generateTmpLinkPure timeNow : '    + timeNow);
        System.debug('## generateTmpLinkPure secret : '     + secret);

        JSONGenerator gen = JSON.createGenerator(true);
        gen.writeStartObject();
        gen.writeStringField('email',email);
        gen.writeStringField('sign', signature(idSf, secret));
        gen.writeStringField('time', String.ValueOf(timeNow));
        String content = gen.getAsString();
        System.debug('## generateTmpLinkPure content : '+ content);

        String sSignContent = signContent(content, secret);
        System.debug('## generateTmpLinkPure return : '+ sSignContent);

        return sSignContent;
    }

    /**
     * Signature the content with a random factor
     *
     * @param string    content
     * @param string    secret
     *
     * @return string   The content in hex with signature (hex too) separated by a '-'
     */
    public static String signContent(string content, string secret){
        System.debug('## signContent content : '+ content);
        System.debug('## signContent secret : ' + secret);

        String content1     = base64UrlEncode(Blob.valueOf(content));
        System.debug('## signContent content1 : ' + content1);

        String content2     = signature(content, secret);
        System.debug('## signContent content2 : ' + content2);

        String sSignContent = content1 + '-' + content2;
        System.debug('## signContent return : ' + sSignContent);

        return sSignContent;
    }

    /**
     * Generate signature from content
     *
     * @param string    content
     * @param string    secret
     *
     * @return string   Signature of the content in base 64 URL compatible
     */
    public static String signature(string content, string secret){
        System.debug('## signature content param : '+ content);
        System.debug('## signature secret param : '+ secret);

        Blob blobSignature = crypto.generateMac('HmacSHA256', Blob.valueOf(content), Blob.valueOf(secret));
        //String signature = EncodingUtil.convertToHex(crypto.generateMac('HmacSHA256', Blob.valueOf(content), Blob.valueOf(secret)));

        /*String signature = EncodingUtil.base64Encode(blobSignature);
        System.debug('## signature SingnatureSHA256 : '+ EncodingUtil.base64Encode(blobSignature));*/

        String signatureBase64 = base64UrlEncode(blobSignature);

        System.debug('## signature return :'+ signatureBase64);

        return signatureBase64;
    }


    /**
     * Custom Base 64 URL compatible encode. Replace '+' or '=' by '._ *'
     *
     * @param string  input
     *
     * @return string input base 64 url compatible
     */
    public static String base64UrlEncode(Blob blobInput){
        System.debug('## base64UrlEncode blobInput param : '+ blobInput);

        String input = EncodingUtil.base64Encode(blobInput);
        System.debug('## base64UrlEncode input Encode : '+ input);

        input = input.replace('+','.');
        input = input.replace('=','*');
        input = input.replace('/','_');
        System.debug('## base64UrlEncode return : '+ input);
        return input;
    }

    /**
     * Custom Base 64 URL compatible decode
     *
     * @param string    input
     *
     * @return string   output decoded
     */
    public static String base64UrlDecode(String input){
        System.debug('## base64UrlDecode input param : '+ input);

        input = input.replace('.','+');
        input = input.replace('*','=');
        input = input.replace('_','/');
        System.debug('## input with replace : '+ input);

        Blob blobInput = EncodingUtil.base64Decode(input);
        System.debug('## base64UrlDecode return :' + blobInput.toString());

        return blobInput.toString();
    }

}