public static IEnumerable <CssRuleBlockSyncAction> ComputeSyncActions(RuleSet existingRule, string newText, string oldText = null)
{
var realOldText = oldText ?? existingRule.Text;
var parser = new CssParser();
var oldDoc = parser.Parse(realOldText, false);
var oldDict = ProduceKeyValuePairsFromRuleSet(oldDoc.Children.OfType <RuleSet>().Single());
if (newText == null && oldText != null)
{
return(OrderAndExtractSyncActions(oldDict.Keys.Select(x => SyncAction.Delete(existingRule, x))));
}
var newDoc = parser.Parse(newText, false);
var newDict = ProduceKeyValuePairsFromRuleSet(newDoc.Children.OfType <RuleSet>().Single());
var oldToNewDiff = CompareNewRuleAndOldRule(existingRule, newDict, oldDict);
var processedElements = new HashSet <string>(oldToNewDiff.Select(x => x.PropertyName));
foreach (var item in oldDict.Keys.Except(processedElements))
{
//Delete
oldToNewDiff.Add(SyncAction.Delete(existingRule, item));
processedElements.Add(item);
}
if (oldText == null)
{
return(oldToNewDiff.Select(x => x.Action));
}
var priorityDiff = ReconcileExistingRuleWithDiff(existingRule, oldToNewDiff);
var combined = priorityDiff.Union(oldToNewDiff);
var simplified = SimplifySyncActions(combined);
return(OrderAndExtractSyncActions(simplified));
}
private static IEnumerable <SyncAction> ReconcileExistingRuleWithDiff(RuleSet comparisonRuleSet, ICollection <SyncAction> oldToNewDiff)
{
var existingDict = ProduceKeyValuePairsFromRuleSet(comparisonRuleSet);
var priorityDiff = new HashSet <SyncAction>();
foreach (var element in oldToNewDiff.Where(x => x.ActionKind == CssDeltaAction.Update || x.ActionKind == CssDeltaAction.Delete))
{
var parts = element.PropertyName.Split('-');
//If the declaration we're looking at is for a property that we've processed in the old -> new rule diff, don't bother with it, it'll get cleaned up on its own
if (parts[0].Length == 0 || existingDict.ContainsKey(element.PropertyName))
{
continue;
}
//Start looking for expansions on the base property that we're examining and delete the ones that aren't explicitly otherwise specified in our diff
//Ex. If we have a record "background", locate "background-color", "background-attachment", etc and delete them if we didn't get them back from the browser (they've been shorthanded)
var prefix = "";
for (var i = 0; i < parts.Length - 1; ++i)
{
if (prefix.Length > 0)
{
prefix += "-";
}
prefix += parts[i];
var localPrefix = prefix;
foreach (var conflictingValue in existingDict.Keys.Where(x => x.StartsWith(localPrefix, StringComparison.Ordinal)))
{
//Leave manually specified long form declarations intact but remove ones that are now shorthand
if (!oldToNewDiff.Contains(SyncAction.NoOp(comparisonRuleSet, conflictingValue)))
{
priorityDiff.Add(SyncAction.Delete(comparisonRuleSet, conflictingValue));
}
}
}
}
return(priorityDiff);
}
private static HashSet <SyncAction> CompareNewRuleAndOldRule(RuleSet comparisonRuleSet, IEnumerable <KeyValuePair <string, string> > newRule, IDictionary <string, string> oldRule)
{
var oldToNewDiff = new HashSet <SyncAction>();
foreach (var entry in newRule)
{
string oldValue;
if (oldRule.TryGetValue(entry.Key, out oldValue))
{
//Possible Update
if (!string.Equals(oldValue, entry.Value))
{
if (!IsValueAnyRepetitionOfInitial(entry.Value))
{
//Update
oldToNewDiff.Add(SyncAction.Update(comparisonRuleSet, entry.Key, entry.Value));
}
else
{
//Delete
oldToNewDiff.Add(SyncAction.Delete(comparisonRuleSet, entry.Key));
}
}
else
{
//Same - don't do anything
oldToNewDiff.Add(SyncAction.NoOp(comparisonRuleSet, entry.Key));
}
}
else if (!IsValueAnyRepetitionOfInitial(entry.Value))
{
//Add
oldToNewDiff.Add(SyncAction.Add(comparisonRuleSet, entry.Key, entry.Value));
}
}
return(oldToNewDiff);
}