Chapter 11 - Chat App/ChatAppFinished/Pods/FirebaseDatabase/Firebase/Database/Snapshot/FLeafNode.m
/*
 * Copyright 2017 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import "FLeafNode.h"
#import "FEmptyNode.h"
#import "FChildrenNode.h"
#import "FConstants.h"
#import "FImmutableSortedDictionary.h"
#import "FUtilities.h"
#import "FStringUtilities.h"
#import "FSnapshotUtilities.h"

@interface FLeafNode ()
@property (nonatomic, strong) id<FNode> priorityNode;
@property (nonatomic, strong) NSString *lazyHash;

@end

@implementation FLeafNode

@synthesize value;
@synthesize priorityNode;

- (id)initWithValue:(id)aValue {
    self = [super init];
    if (self) {
        self.value = aValue;
        self.priorityNode = [FEmptyNode emptyNode];
    }
    return self;
}

- (id)initWithValue:(id)aValue withPriority:(id<FNode>)aPriority {
    self = [super init];
    if (self) {
        self.value = aValue;
        [FSnapshotUtilities validatePriorityNode:aPriority];
        self.priorityNode = aPriority;
    }
    return self;
}

#pragma mark -
#pragma mark FNode methods

- (BOOL) isLeafNode {
    return YES;
}

- (id<FNode>) getPriority {
    return self.priorityNode;
}

- (id<FNode>) updatePriority:(id<FNode>)aPriority {
    return [[FLeafNode alloc] initWithValue:self.value withPriority:aPriority];
}

- (id<FNode>) getImmediateChild:(NSString *) childName {
    if ([childName isEqualToString:@".priority"]) {
        return self.priorityNode;
    } else {
        return [FEmptyNode emptyNode];
    }
}

- (id<FNode>) getChild:(FPath *)path {
    if (path.getFront == nil) {
        return self;
    } else if ([[path getFront] isEqualToString:@".priority"]) {
        return [self getPriority];
    } else {
        return [FEmptyNode emptyNode];
    }
}

- (BOOL)hasChild:(NSString *)childName {
    return [childName isEqualToString:@".priority"] && ![self getPriority].isEmpty;
}


- (NSString *)predecessorChildKey:(NSString *)childKey
{
    return nil;
}

- (id<FNode>) updateImmediateChild:(NSString *)childName withNewChild:(id<FNode>)newChildNode {
    if ([childName isEqualToString:@".priority"]) {
        return [self updatePriority:newChildNode];
    } else if (newChildNode.isEmpty) {
        return self;
    } else {
        FChildrenNode* childrenNode = [[FChildrenNode alloc] init];
        childrenNode = [childrenNode updateImmediateChild:childName withNewChild:newChildNode];
        childrenNode = [childrenNode updatePriority:self.priorityNode];
        return childrenNode;
    }
}

- (id<FNode>) updateChild:(FPath *)path withNewChild:(id<FNode>)newChildNode {
    NSString* front = [path getFront];
    if(front == nil) {
        return newChildNode;
    } else if (newChildNode.isEmpty && ![front isEqualToString:@".priority"]) {
        return self;
    } else {
        NSAssert(![front isEqualToString:@".priority"] || path.length == 1, @".priority must be the last token in a path.");
        return [self updateImmediateChild:front withNewChild:
                [[FEmptyNode emptyNode] updateChild:[path popFront] withNewChild:newChildNode]];
    }
}

- (id) val {
    return [self valForExport:NO];
}

- (id) valForExport:(BOOL)exp {
    if(exp && !self.getPriority.isEmpty) {
        return @{kPayloadValue : self.value,
                kPayloadPriority : [[self getPriority] val]};
    }
    else {
        return self.value;
    }
}

- (BOOL)isEqual:(id <FNode>)other {
    if(other == self) {
        return YES;
    } else if (other.isLeafNode) {
        FLeafNode *otherLeaf = other;
        if ([FUtilities getJavascriptType:self.value] != [FUtilities getJavascriptType:otherLeaf.value]) {
            return NO;
        }
        return [otherLeaf.value isEqual:self.value] && [otherLeaf.priorityNode isEqual:self.priorityNode];
    } else {
        return NO;
    }
}

- (NSUInteger)hash {
    return [self.value hash] * 17 + self.priorityNode.hash;
}

- (id <FNode>)withIndex:(id <FIndex>)index {
    return self;
}

- (BOOL)isIndexed:(id <FIndex>)index {
    return YES;
}

- (BOOL) isEmpty {
    return NO;
}

- (int) numChildren {
    return 0;
}

- (void) enumerateChildrenUsingBlock:(void (^)(NSString *, id<FNode>, BOOL *))block
{
    // Nothing to iterate over
}

- (void) enumerateChildrenReverse:(BOOL)reverse usingBlock:(void (^)(NSString *, id<FNode>, BOOL *))block
{
    // Nothing to iterate over
}

- (NSEnumerator *)childEnumerator
{
    // Nothing to iterate over
    return [@[] objectEnumerator];
}

- (NSString *) dataHash {
    if (self.lazyHash == nil) {
        NSMutableString *toHash = [[NSMutableString alloc] init];
        [FSnapshotUtilities appendHashRepresentationForLeafNode:self toString:toHash hashVersion:FDataHashVersionV1];

        self.lazyHash = [FStringUtilities base64EncodedSha1:toHash];
    }
    return self.lazyHash;
}

- (NSComparisonResult)compare:(id <FNode>)other {
    if (other == [FEmptyNode emptyNode]) {
        return NSOrderedDescending;
    } else if ([other isKindOfClass:[FChildrenNode class]]) {
        return NSOrderedAscending;
    } else {
        NSAssert(other.isLeafNode, @"Compared against unknown type of node.");
        return [self compareToLeafNode:(FLeafNode*)other];
    }
}

+ (NSArray*) valueTypeOrder {
    static NSArray* valueOrder = nil;
    static dispatch_once_t once;
    dispatch_once(&once, ^{
        valueOrder = @[kJavaScriptObject, kJavaScriptBoolean, kJavaScriptNumber, kJavaScriptString];
    });
    return valueOrder;
}

- (NSComparisonResult) compareToLeafNode:(FLeafNode*)other {
    NSString* thisLeafType = [FUtilities getJavascriptType:self.value];
    NSString* otherLeafType = [FUtilities getJavascriptType:other.value];
    NSUInteger thisIndex = [[FLeafNode valueTypeOrder] indexOfObject:thisLeafType];
    NSUInteger otherIndex = [[FLeafNode valueTypeOrder] indexOfObject:otherLeafType];
    assert(thisIndex >= 0 && otherIndex >= 0);
    if (otherIndex == thisIndex) {
        // Same type.  Compare values.
        if (thisLeafType == kJavaScriptObject) {
            // Deferred value nodes are all equal, but we should also never get to this point...
            return NSOrderedSame;
        } else if (thisLeafType == kJavaScriptString) {
            return [self.value compare:other.value options:NSLiteralSearch];
        } else {
            return [self.value compare:other.value];
        }
    } else {
        return thisIndex > otherIndex ? NSOrderedDescending : NSOrderedAscending;
    }
}

- (NSString *) description {
    return [[self valForExport:YES] description];
}

- (void) forEachChildDo:(fbt_bool_nsstring_node)action {
    // There are no children, so there is nothing to do.
    return;
}


@end
