/** 
  * Description     :   Login Page controller.
  *
  * Created By      :   Abhi Tripathi 
  *                
  * Created Date    :   2/4/2014    
  *
  * Revision Log    :   V1.0
  **/
public without sharing class LoginController {
      
    //Email Id and Password
    public String emailId { get; set; }  
    public String password { get; set; }

    //Constructor  
    public LoginController() {
    
	//Initiallizing the variables
        emailId = '';
        password = '';
    }

    /**
     * @Description  :  Method used when user tries to get loggin.
     *
     * @args         :  
     *
     * @return       :  PageReference
     *
    **/    
    public PageReference login() {

	//Check the values entered by the user
        if(emailId != Null && emailId != '' && password != Null && password != '') {
                  
            //Query on Contact records Weather the email id Entered by the user exists
            contact = [ Select Email, Password__c From Contact Where Email =: emailId LIMIT 1];
            
            //Check for Contact
            if(contact.size() > 0) {
            
                //Comparing password from the database
                if( contact[0].Password__c.compareTo(password) == 0) {
        
		    //Page Url set
                    PageReference newPage = New PageReference('/apex/YOUR-NEXT-PAGE-AFTER-LOGIN');

                    //Reinitiallize all the atribute by this
                    newPage.setRedirect(false);
                        
                    //Return to page
                    return newPage;
            
                } else {
                    
                    //Message method when no field is filled
                    ApexPages.addMessage(new ApexPages.message(ApexPages.severity.ERROR, 'ERROR MESSAGES' ));
                }
            }
        }
        
        return null;
    }
}