changed: refactored maximum-submission-size determination logic,

closes kobotoolbox#341

- never store default max size in db (offline-capable views)
- always attempt to obtain max size from server if not stored in db (offline-capable views)
- only set default max size at 1 point in code (instead of 3)
- do not make submission/max-size request during previews without enketo ID
- log error to console if OpenRosa server does not return X-OpenRosa-Accept-Content-Length header

app/lib/communicator/communicator.js

@@ -104,7 +104,7 @@ function getMaxSize( survey ) {
 
     return _request( options )
         .then( function( response ) {
-            return response.headers[ 'x-openrosa-accept-content-length' ] || 5 * 1024 * 1024;
+            return response.headers[ 'x-openrosa-accept-content-length' ];
         } );
 }
 

public/js/src/main-webform-edit.js

@@ -41,14 +41,19 @@ translator.init( survey )
                     _init( formParts );
                 } )
                 .then( connection.getMaximumSubmissionSize )
-                .then( function( maxSize ) {
-                    settings.maxSize = maxSize;
-                } );
+                .then( _updateMaxSizeSetting );
         } else {
             throw new Error( t( 'error.unknown' ) );
         }
     } ).catch( _showErrorOrAuthenticate );
 
+function _updateMaxSizeSetting( maxSize ) {
+    if ( maxSize ) {
+        // overwrite default max size
+        settings.maxSize = maxSize;
+    }
+}
+
 function _showErrorOrAuthenticate( error ) {
     $loader.addClass( 'fail' );
     if ( error.status === 401 ) {

public/js/src/main-webform.js

@@ -39,7 +39,7 @@ if ( settings.offline ) {
         .then( formCache.updateMaxSubmissionSize )
         .then( formCache.updateMedia )
         .then( function( s ) {
-            settings.maxSize = s.maxSize;
+            _updateMaxSizeSetting( s.maxSize );
             _setFormCacheEventHandlers();
             _setAppCacheEventHandlers();
             appCache.init();
@@ -54,12 +54,17 @@ if ( settings.offline ) {
         .then( _swapTheme )
         .then( _init )
         .then( connection.getMaximumSubmissionSize )
-        .then( function( maxSize ) {
-            settings.maxSize = maxSize;
-        } )
+        .then( _updateMaxSizeSetting )
         .catch( _showErrorOrAuthenticate );
 }
 
+function _updateMaxSizeSetting( maxSize ) {
+    if ( maxSize ) {
+        // overwrite default max size
+        settings.maxSize = maxSize;
+    }
+}
+
 function _showErrorOrAuthenticate( error ) {
     error = ( typeof error === 'string' ) ? new Error( error ) : error;
     console.error( error, error.stack );

public/js/src/module/connection.js

@@ -17,7 +17,6 @@ var TRANSFORM_HASH_URL = '/transform/xform/hash';
 var EXPORT_URL = '/export/get-url';
 var INSTANCE_URL = ( settings.enketoId ) ? '/submission/' + settings.enketoIdPrefix + settings.enketoId : null;
 var MAX_SIZE_URL = ( settings.enketoId ) ? '/submission/max-size/' + settings.enketoIdPrefix + settings.enketoId : null;
-var DEFAULT_MAX_SIZE = 5 * 1024 * 1024;
 var ABSOLUTE_MAX_SIZE = 100 * 1024 * 1024;
 
 /**
@@ -310,7 +309,8 @@ function getMaximumSubmissionSize() {
     var maxSubmissionSize;
 
     return new Promise( function( resolve ) {
-        if ( MAX_SIZE_URL ) {
+
+        if ( MAX_SIZE_URL && settings.type !== 'preview' && settings.type !== 'app' ) {
             $.ajax( MAX_SIZE_URL, {
                     type: 'GET',
                     timeout: 5 * 1000,
@@ -321,15 +321,16 @@ function getMaximumSubmissionSize() {
                         maxSubmissionSize = ( Number( response.maxSize ) > ABSOLUTE_MAX_SIZE ) ? ABSOLUTE_MAX_SIZE : Number( response.maxSize );
                         resolve( maxSubmissionSize );
                     } else {
+                        console.error( 'Error retrieving maximum submission size. Unexpected response: ', response );
                         // Note that in /previews the MAX_SIZE_URL is null, which will immediately call this handler
-                        resolve( DEFAULT_MAX_SIZE );
+                        resolve( null );
                     }
                 } )
                 .fail( function() {
-                    resolve( DEFAULT_MAX_SIZE );
+                    resolve( null );
                 } );
         } else {
-            resolve( DEFAULT_MAX_SIZE );
+            resolve( null );
         }
     } );
 }

public/js/src/module/form-cache.js

@@ -163,15 +163,15 @@ function updateMaxSubmissionSize( survey ) {
         return connection.getMaximumSubmissionSize()
             .then( function( maxSize ) {
                 survey.maxSize = maxSize;
-                return survey;
+                return store.survey.update( survey );
             } );
     } else {
         return Promise.resolve( survey );
     }
 }
 
 /**
- * Loads survey resources either from the store or via HTTP (and stores them)
+ * Loads survey resources either from the store or via HTTP (and stores them).
  *
  * @param  {[type]} survey [description]
  * @return {Promise}        [description]

public/js/src/module/settings.js

@@ -3,6 +3,7 @@
 var config = require( 'enketo-config' );
 var queryParams = _getAllQueryParams();
 var settings = {};
+var DEFAULT_MAX_SIZE = 5 * 1024 * 1024;
 var settingsMap = [ {
     q: 'return',
     s: 'returnUrl'
@@ -90,6 +91,12 @@ if ( settings.submissionParameter && settings.submissionParameter.name ) {
     settings.submissionParameter.value = queryParams[ settings.submissionParameter.name ];
 }
 
+// set default maxSubmissionSize
+settings.maxSize = DEFAULT_MAX_SIZE;
+
+// add type
+settings.type = ( window.location.pathname.indexOf( '/preview' ) === 0 ) ? 'preview' : 'other';
+
 // add enketoId
 settings.enketoIdPrefix = '::';
 settings.enketoId = _getEnketoId( '\/' + settings.enketoIdPrefix, window.location.pathname ) || _getEnketoId( '#', window.location.hash );