package org.litesoft.useragent;

public class UserAgentFormFactorDeterminerImpl implements UserAgentFormFactorDeterminer {
    @Override
    public UserAgentFormFactor determine( String pUserAgent ) {
        return ((pUserAgent.length() > 15) && containsAnyOf( pUserAgent,
                                                             "iPhone", "iPod", "Mobile", "Android", "iPad", "IEMobile", "Tablet",
                                                             "Kindle", "Silk",
                                                             "SymbianOS", "Symbian",
                                                             "Opera Mini", "Opera Mobi",
                                                             "Fennec" )) ?
               UserAgentFormFactor.SingleViewOnly :
               UserAgentFormFactor.MultiViewable;
    }

    /**
     * Look for the Find Words (where the Word may not start the User Agent).
     */
    private boolean containsAnyOf( String pUserAgent, String... pFindWords ) {
        for ( String zWord : pFindWords ) {
            if ( containsWord( pUserAgent, zWord ) ) {
                return true;
            }
        }
        return false;
    }

    /**
     * Look for the Find Word (where the Word may not start the User Agent).
     */
    private boolean containsWord( String pUserAgent, String pWord ) {
        for ( int zAt, zFrom = 1; -1 != (zAt = pUserAgent.indexOf( pWord, zFrom )); ) {
            zFrom = zAt + pWord.length();
            if ( isWordSep( pUserAgent, zAt - 1 ) && isWordSep( pUserAgent, zFrom ) ) {
                return true;
            }
        }
        return false;
    }

    private boolean isWordSep( String pUserAgent, int pAt ) {
        return (pAt == pUserAgent.length()) || !Character.isLetterOrDigit( pUserAgent.charAt( pAt ) );
    }
}