Chapter 11 - Chat App/ChatAppFinished/Pods/FirebaseDatabase/Firebase/Database/Core/Utilities/FTree.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 "FTree.h"
#import "FTreeNode.h"
#import "FPath.h"
#import "FUtilities.h"

@implementation FTree

@synthesize name;
@synthesize parent;
@synthesize node;

- (id)init
{
    self = [super init];
    if (self) {
        self.name = @"";
        self.parent = nil;
        self.node = [[FTreeNode alloc] init];
    }
    return self;
}


- (id)initWithName:(NSString*)aName withParent:(FTree *)aParent withNode:(FTreeNode *)aNode
{
    self = [super init];
    if (self) {
        self.name = aName != nil ? aName : @"";
        self.parent = aParent != nil ? aParent : nil;
        self.node = aNode != nil ? aNode : [[FTreeNode alloc] init];
    }
    return self;
}

- (FTree *) subTree:(FPath*)path {
    FTree* child = self;
    NSString* next = [path getFront];
    while(next != nil) {
        FTreeNode* childNode = child.node.children[next];
        if (childNode == nil) {
            childNode = [[FTreeNode alloc] init];
        }
        child = [[FTree alloc] initWithName:next withParent:child withNode:childNode];
        path = [path popFront];
        next = [path getFront];
    }
    return child;
}

- (id)getValue {
    return self.node.value;
}

- (void)setValue:(id)value {
    self.node.value = value;
    [self updateParents];
}

- (void) clear {
    self.node.value = nil;
    [self.node.children removeAllObjects];
    self.node.childCount = 0;
    [self updateParents];
}

- (BOOL) hasChildren {
    return self.node.childCount > 0;
}

- (BOOL) isEmpty {
    return [self getValue] == nil && ![self hasChildren];
}

- (void) forEachChild:(void (^)(FTree *))action {
    for(NSString* key in self.node.children) {
        action([[FTree alloc] initWithName:key withParent:self withNode:[self.node.children objectForKey:key]]);
    }
}

- (void) forEachChildMutationSafe:(void (^)(FTree *))action {
    for(NSString* key in [self.node.children copy]) {
        action([[FTree alloc] initWithName:key withParent:self withNode:[self.node.children objectForKey:key]]);
    }
}

- (void) forEachDescendant:(void (^)(FTree *))action {
    [self forEachDescendant:action includeSelf:NO childrenFirst:NO];
}

- (void) forEachDescendant:(void (^)(FTree *))action includeSelf:(BOOL)incSelf childrenFirst:(BOOL)childFirst {
    if(incSelf && !childFirst) {
        action(self);
    }

    [self forEachChild:^(FTree* child) {
        [child forEachDescendant:action includeSelf:YES childrenFirst:childFirst];
    }];

    if(incSelf && childFirst) {
        action(self);
    }
}

- (BOOL) forEachAncestor:(BOOL (^)(FTree *))action {
    return [self forEachAncestor:action includeSelf:NO];
}

- (BOOL) forEachAncestor:(BOOL (^)(FTree *))action includeSelf:(BOOL)incSelf {
    FTree* aNode = (incSelf) ? self : self.parent;
    while(aNode != nil) {
        if(action(aNode)) {
            return YES;
        }
        aNode = aNode.parent;
    }
    return NO;
}

- (void) forEachImmediateDescendantWithValue:(void (^)(FTree *))action {
    [self forEachChild:^(FTree * child) {
        if([child getValue] != nil) {
            action(child);
        }
        else {
            [child forEachImmediateDescendantWithValue:action];
        }
    }];
}

- (BOOL) valueExistsAtOrAbove:(FPath *)path {
    FTreeNode* aNode = self.node;
    while(aNode != nil) {
        if(aNode.value != nil) {
            return YES;
        }
        aNode = [aNode.children objectForKey:path.getFront];
        path = [path popFront];
    }
    // XXX Check with Michael if this is correct; deviates from JS.
    return NO;
}

- (FPath *)path {
    return [[FPath alloc] initWith:(self.parent == nil) ? self.name :
            [NSString stringWithFormat:@"%@/%@", [self.parent path], self.name ]];
}

- (void) updateParents {
    [self.parent updateChild:self.name withNode:self];
}

- (void) updateChild:(NSString*)childName withNode:(FTree *)child {
    BOOL childEmpty = [child isEmpty];
    BOOL childExists = self.node.children[childName] != nil;
    if(childEmpty && childExists) {
        [self.node.children removeObjectForKey:childName];
        self.node.childCount = self.node.childCount - 1;
        [self updateParents];
    }
    else if(!childEmpty && !childExists) {
        [self.node.children setObject:child.node forKey:childName];
        self.node.childCount = self.node.childCount + 1;
        [self updateParents];
    }
}

@end
