#import "RNFirebase.h"
#import "RNFirebaseDatabase.h"
#import "RNFirebaseEvents.h"

@interface RNFirebaseDBReference : NSObject
@property RCTEventEmitter *emitter;
@property FIRDatabaseQuery *query;
@property NSNumber *refId;
@property NSString *path;
@property NSMutableDictionary *listeners;
+ (NSDictionary *) snapshotToDict:(FIRDataSnapshot *) snapshot;
@end

@implementation RNFirebaseDBReference


- (id) initWithPathAndModifiers:(RCTEventEmitter *) emitter
                       database:(FIRDatabase *) database
                          refId:(NSNumber *) refId
                           path:(NSString *) path
                      modifiers:(NSArray *) modifiers
{
    self = [super init];
    if (self) {
        _emitter = emitter;
        _refId = refId;
        _path = path;
        _query = [self buildQueryAtPathWithModifiers:database path:path modifiers:modifiers];
        _listeners = [[NSMutableDictionary alloc] init];
    }
    return self;
}

- (void) addEventHandler:(NSNumber *) listenerId
               eventName:(NSString *) eventName
{
    if (![_listeners objectForKey:listenerId]) {
        id withBlock = ^(FIRDataSnapshot * _Nonnull snapshot) {
            NSDictionary *props = [RNFirebaseDBReference snapshotToDict:snapshot];
            [self sendJSEvent:DATABASE_DATA_EVENT
                        title:eventName
                        props: @{
                                 @"eventName": eventName,
                                 @"refId": _refId,
                                 @"listenerId": listenerId,
                                 @"path": _path,
                                 @"snapshot": props
                                 }];
        };
        id errorBlock = ^(NSError * _Nonnull error) {
            NSLog(@"Error onDBEvent: %@", [error debugDescription]);
            [self removeEventHandler:listenerId eventName:eventName];
            [self getAndSendDatabaseError:error
                               listenerId:listenerId];
        };
        int eventType = [self eventTypeFromName:eventName];
        FIRDatabaseHandle handle = [_query observeEventType:eventType
                                                  withBlock:withBlock
                                            withCancelBlock:errorBlock];
        [_listeners setObject:@(handle) forKey:listenerId];
    } else {
        NSLog(@"Warning Trying to add duplicate listener for refId: %@ listenerId: %@", _refId, listenerId);
    }
}

- (void) addSingleEventHandler:(RCTResponseSenderBlock) callback
{
    [_query observeSingleEventOfType:FIRDataEventTypeValue
                           withBlock:^(FIRDataSnapshot * _Nonnull snapshot) {
                               NSDictionary *props = [RNFirebaseDBReference snapshotToDict:snapshot];
                               callback(@[[NSNull null], @{
                                              @"eventName": @"value",
                                              @"path": _path,
                                              @"refId": _refId,
                                              @"snapshot": props
                                              }]);
                           }
                     withCancelBlock:^(NSError * _Nonnull error) {
                         NSLog(@"Error onDBEventOnce: %@", [error debugDescription]);
                         callback(@[@{
                                        @"eventName": DATABASE_ERROR_EVENT,
                                        @"path": _path,
                                        @"refId": _refId,
                                        @"code": @([error code]),
                                        @"details": [error debugDescription],
                                        @"message": [error localizedDescription],
                                        @"description": [error description]
                                        }]);
                     }];
}

- (void) removeEventHandler:(NSNumber *) listenerId
                  eventName:(NSString *) eventName
{
    FIRDatabaseHandle handle = [[_listeners objectForKey:listenerId] integerValue];
    if (handle) {
        [_listeners removeObjectForKey:listenerId];
        [_query removeObserverWithHandle:handle];
    }
}

+ (NSDictionary *) snapshotToDict:(FIRDataSnapshot *) snapshot
{
    NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
    [dict setValue:snapshot.key forKey:@"key"];
    NSDictionary *val = snapshot.value;
    [dict setObject:val forKey:@"value"];
    // Snapshot ordering
    NSMutableArray *childKeys = [NSMutableArray array];
    if (snapshot.childrenCount > 0) {
        // Since JS does not respect object ordering of keys
        // we keep a list of the keys and their ordering
        // in the snapshot event
        NSEnumerator *children = [snapshot children];
        FIRDataSnapshot *child;
        while(child = [children nextObject]) {
            [childKeys addObject:child.key];
        }
    }
    [dict setObject:childKeys forKey:@"childKeys"];
    [dict setValue:@(snapshot.hasChildren) forKey:@"hasChildren"];
    [dict setValue:@(snapshot.exists) forKey:@"exists"];
    [dict setValue:@(snapshot.childrenCount) forKey:@"childrenCount"];
    [dict setValue:snapshot.priority forKey:@"priority"];
    return dict;
}

- (NSDictionary *) getAndSendDatabaseError:(NSError *) error
                                listenerId:(NSNumber *) listenerId
{
    NSDictionary *event = @{
                            @"eventName": DATABASE_ERROR_EVENT,
                            @"path": _path,
                            @"refId": _refId,
                            @"listenerId": listenerId,
                            @"code": @([error code]),
                            @"details": [error debugDescription],
                            @"message": [error localizedDescription],
                            @"description": [error description]
                            };

    @try {
        [_emitter sendEventWithName:DATABASE_ERROR_EVENT body:event];
    }
    @catch (NSException *err) {
        NSLog(@"An error occurred in getAndSendDatabaseError: %@", [err debugDescription]);
        NSLog(@"Tried to send: %@ with %@", DATABASE_ERROR_EVENT, event);
    }

    return event;
}

- (void) sendJSEvent:(NSString *)type title:(NSString *)title props:(NSDictionary *)props {
    @try {
        [_emitter sendEventWithName:type body:@{ @"eventName": title, @"body": props }];
    }  @catch (NSException *err) {
        NSLog(@"An error occurred in sendJSEvent: %@", [err debugDescription]);
        NSLog(@"Tried to send: %@ with %@", title, props);
    }
}

- (FIRDatabaseQuery *) buildQueryAtPathWithModifiers:(FIRDatabase*) database
                                                path:(NSString*) path
                                           modifiers:(NSArray *) modifiers
{
    FIRDatabaseQuery *query = [[database reference] child:path];

    for (NSDictionary *modifier in modifiers) {
        NSString *type = [modifier valueForKey:@"type"];
        NSString *name = [modifier valueForKey:@"name"];
        if ([type isEqualToString:@"orderBy"]) {
            if ([name isEqualToString:@"orderByKey"]) {
                query = [query queryOrderedByKey];
            } else if ([name isEqualToString:@"orderByPriority"]) {
                query = [query queryOrderedByPriority];
            } else if ([name isEqualToString:@"orderByValue"]) {
                query = [query queryOrderedByValue];
            } else if ([name isEqualToString:@"orderByChild"]) {
                NSString *key = [modifier valueForKey:@"key"];
                query = [query queryOrderedByChild:key];
            }
        } else if ([type isEqualToString:@"limit"]) {
            int limit = [[modifier valueForKey:@"limit"] integerValue];
            if ([name isEqualToString:@"limitToLast"]) {
                query = [query queryLimitedToLast:limit];
            } else if ([name isEqualToString:@"limitToFirst"]) {
                query = [query queryLimitedToFirst:limit];
            }
        } else if ([type isEqualToString:@"filter"]) {
            NSString* valueType = [modifier valueForKey:@"valueType"];
            NSString* key = [modifier valueForKey:@"key"];
            id value = [self getIdValue:[modifier valueForKey:@"value"] type:valueType];
            if ([name isEqualToString:@"equalTo"]) {
                if (key != nil) {
                    query = [query queryEqualToValue:value childKey:key];
                } else {
                    query = [query queryEqualToValue:value];
                }
            } else if ([name isEqualToString:@"endAt"]) {
                if (key != nil) {
                    query = [query queryEndingAtValue:value childKey:key];
                } else {
                    query = [query queryEndingAtValue:value];
                }
            } else if ([name isEqualToString:@"startAt"]) {
                if (key != nil) {
                    query = [query queryStartingAtValue:value childKey:key];
                } else {
                    query = [query queryStartingAtValue:value];
                }
            }
        }
    }

    return query;
}

- (id) getIdValue:(NSString *) value
             type:(NSString *) type
{
    if ([type isEqualToString:@"number"]) {
        return [NSNumber numberWithInteger:value.integerValue];
    } else if ([type isEqualToString:@"boolean"]) {
        return [NSNumber numberWithBool:value.boolValue];
    } else {
        return value;
    }
}

- (BOOL) hasListeners
{
    return [[_listeners allKeys] count] > 0;
}

- (int) eventTypeFromName:(NSString *)name
{
    int eventType = FIRDataEventTypeValue;

    if ([name isEqualToString:DATABASE_VALUE_EVENT]) {
        eventType = FIRDataEventTypeValue;
    } else if ([name isEqualToString:DATABASE_CHILD_ADDED_EVENT]) {
        eventType = FIRDataEventTypeChildAdded;
    } else if ([name isEqualToString:DATABASE_CHILD_MODIFIED_EVENT]) {
        eventType = FIRDataEventTypeChildChanged;
    } else if ([name isEqualToString:DATABASE_CHILD_REMOVED_EVENT]) {
        eventType = FIRDataEventTypeChildRemoved;
    } else if ([name isEqualToString:DATABASE_CHILD_MOVED_EVENT]) {
        eventType = FIRDataEventTypeChildMoved;
    }
    return eventType;
}

@end


@implementation RNFirebaseDatabase

RCT_EXPORT_MODULE(RNFirebaseDatabase);

- (id) init {
    self = [super init];
    if (self != nil) {
        _dbReferences = [[NSMutableDictionary alloc] init];
        _transactions = [[NSMutableDictionary alloc] init];
        _transactionQueue = dispatch_queue_create("io.invertase.react-native-firebase", DISPATCH_QUEUE_CONCURRENT);
    }
    return self;
}

- (void) sendTransactionEvent:(NSString *)type body:(id)body {
    @try {
        [self sendEventWithName:type body:body];
    }  @catch (NSException *err) {
        NSLog(@"An error occurred in sendJSEvent: %@", [err debugDescription]);
        NSLog(@"Tried to send: %@ with %@", type, body);
    }
}

RCT_EXPORT_METHOD(startTransaction:(NSString *) path identifier:(NSString *) identifier applyLocally:(BOOL) applyLocally) {
    dispatch_async(_transactionQueue, ^{
        NSMutableDictionary *transactionState = [NSMutableDictionary new];
        dispatch_semaphore_t sema = dispatch_semaphore_create(0);
        [transactionState setObject:sema forKey:@"semaphore"];
        FIRDatabaseReference *ref = [self getPathRef:path];

        [ref runTransactionBlock:^FIRTransactionResult * _Nonnull(FIRMutableData * _Nonnull currentData) {
            dispatch_barrier_async(_transactionQueue, ^{
                [_transactions setValue:transactionState forKey:identifier];
                [self sendTransactionEvent:DATABASE_TRANSACTION_EVENT body:@{ @"id": identifier, @"type": @"update", @"value": currentData.value }];
            });

            // wait for the js event handler to call tryCommitTransaction
            // this wait occurs on the Firebase Worker Queue
            // so if the tryCommitTransaction fails to signal the semaphore
            // no further blocks will be executed by Firebase until the timeout expires
            dispatch_time_t delayTime = dispatch_time(DISPATCH_TIME_NOW, 30 * NSEC_PER_SEC);
            BOOL timedout = dispatch_semaphore_wait(sema, delayTime) != 0;

            BOOL abort = [transactionState valueForKey:@"abort"] || timedout;
            id value = [transactionState valueForKey:@"value"];

            dispatch_barrier_async(_transactionQueue, ^{
                [_transactions removeObjectForKey:identifier];
            });

            if (abort) {
                return [FIRTransactionResult abort];
            } else {
                currentData.value = value;
                return [FIRTransactionResult successWithValue:currentData];
            }
        } andCompletionBlock:^(NSError * _Nullable databaseError, BOOL committed, FIRDataSnapshot * _Nullable snapshot) {
            if (databaseError != nil) {
                [self sendTransactionEvent:DATABASE_TRANSACTION_EVENT body:@{
                                                                             @"id": identifier,
                                                                             @"type": @"error",
                                                                             @"code": [NSNumber numberWithInt:[databaseError code]],
                                                                             @"message": [databaseError description]
                                                                             }];
            } else {
                [self sendTransactionEvent:DATABASE_TRANSACTION_EVENT body:@{
                                                                             @"id": identifier,
                                                                             @"type": @"complete",
                                                                             @"committed": @(committed),
                                                                             @"snapshot": [RNFirebaseDBReference snapshotToDict:snapshot],
                                                                             }];
            }
        } withLocalEvents:applyLocally];
    });
}

RCT_EXPORT_METHOD(tryCommitTransaction:(NSString *) identifier withData:(NSDictionary *) data) {
    __block NSMutableDictionary *transactionState;

    dispatch_sync(_transactionQueue, ^{
        transactionState = [_transactions objectForKey: identifier];
    });

    if (!transactionState) {
        NSLog(@"tryCommitTransaction for unknown ID %@", identifier);
        return;
    }

    dispatch_semaphore_t sema = [transactionState valueForKey:@"semaphore"];

    BOOL abort = [[data valueForKey:@"abort"] boolValue];

    if (abort) {
        [transactionState setValue:@true forKey:@"abort"];
    } else {
        id newValue = [data valueForKey:@"value"];
        [transactionState setValue:newValue forKey:@"value"];
    }

    dispatch_semaphore_signal(sema);
}

RCT_EXPORT_METHOD(enablePersistence:(BOOL) enable
                  callback:(RCTResponseSenderBlock) callback)
{

    BOOL isEnabled = [FIRDatabase database].persistenceEnabled;
    if ( isEnabled != enable) {
        [FIRDatabase database].persistenceEnabled = enable;
    }
    callback(@[[NSNull null], @{
                   @"result": @"success"
                   }]);
}

RCT_EXPORT_METHOD(keepSynced:(NSString *) path
                  withEnable:(BOOL) enable
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    [ref keepSynced:enable];
    callback(@[[NSNull null], @{
                   @"status": @"success",
                   @"path": path
                   }]);
}

RCT_EXPORT_METHOD(set:(NSString *) path
                  data:(NSDictionary *)data
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    [ref setValue:[data valueForKey:@"value"] withCompletionBlock:^(NSError * _Nullable error, FIRDatabaseReference * _Nonnull ref) {
        [self handleCallback:@"set" callback:callback databaseError:error];
    }];
}

RCT_EXPORT_METHOD(update:(NSString *) path
                  value:(NSDictionary *)value
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    [ref updateChildValues:value withCompletionBlock:^(NSError * _Nullable error, FIRDatabaseReference * _Nonnull ref) {
        [self handleCallback:@"update" callback:callback databaseError:error];
    }];
}

RCT_EXPORT_METHOD(remove:(NSString *) path
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    [ref removeValueWithCompletionBlock:^(NSError * _Nullable error, FIRDatabaseReference * _Nonnull ref) {
        [self handleCallback:@"remove" callback:callback databaseError:error];
    }];
}

RCT_EXPORT_METHOD(push:(NSString *) path
                  data:(NSDictionary *) data
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    FIRDatabaseReference *newRef = [ref childByAutoId];

    NSURL *url = [NSURL URLWithString:newRef.URL];
    NSString *newPath = [url path];

    if ([data count] > 0) {
        [newRef setValue:[data valueForKey:@"value"] withCompletionBlock:^(NSError * _Nullable error, FIRDatabaseReference * _Nonnull ref) {
            if (error != nil) {
                // Error handling
                NSDictionary *evt = @{
                                      @"code": @([error code]),
                                      @"details": [error debugDescription],
                                      @"message": [error localizedDescription],
                                      @"description": [error description]
                                      };

                callback(@[evt]);
            } else {
                callback(@[[NSNull null], @{
                               @"status": @"success",
                               @"ref": newPath
                               }]);
            }
        }];
    } else {
        callback(@[[NSNull null], @{
                       @"status": @"success",
                       @"ref": newPath
                       }]);
    }
}


RCT_EXPORT_METHOD(on:(nonnull NSNumber *) refId
                  path:(NSString *) path
                  modifiers:(NSArray *) modifiers
                  listenerId:(nonnull NSNumber *) listenerId
                  name:(NSString *) eventName
                  callback:(RCTResponseSenderBlock) callback)
{
    RNFirebaseDBReference *ref = [self getDBHandle:refId path:path modifiers:modifiers];
    [ref addEventHandler:listenerId eventName:eventName];
    callback(@[[NSNull null], @{
                   @"status": @"success",
                   @"refId": refId,
                   @"handle": path
                   }]);
}

RCT_EXPORT_METHOD(once:(nonnull NSNumber *) refId
                  path:(NSString *) path
                  modifiers:(NSArray *) modifiers
                  eventName:(NSString *) eventName
                  callback:(RCTResponseSenderBlock) callback)
{
    RNFirebaseDBReference *ref = [self getDBHandle:refId path:path modifiers:modifiers];
    [ref addSingleEventHandler:callback];
}

RCT_EXPORT_METHOD(off:(nonnull NSNumber *) refId
                  listeners:(NSArray *) listeners
                  callback:(RCTResponseSenderBlock) callback)
{
    RNFirebaseDBReference *ref = [_dbReferences objectForKey:refId];
    if (ref != nil) {
        for (NSDictionary *listener in listeners) {
            NSNumber *listenerId = [listener valueForKey:@"listenerId"];
            NSString *eventName = [listener valueForKey:@"eventName"];
            [ref removeEventHandler:listenerId eventName:eventName];
            if (![ref hasListeners]) {
                [_dbReferences removeObjectForKey:refId];
            }
        }
    }
    callback(@[[NSNull null], @{
                   @"status": @"success",
                   @"refId": refId,
                   }]);
}

// On disconnect
RCT_EXPORT_METHOD(onDisconnectSet:(NSString *) path
                  props:(NSDictionary *) props
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    [ref onDisconnectSetValue:props[@"value"]
          withCompletionBlock:^(NSError * _Nullable error, FIRDatabaseReference * _Nonnull ref) {
              [self handleCallback:@"onDisconnectSetObject" callback:callback databaseError:error];
          }];
}

RCT_EXPORT_METHOD(onDisconnectRemove:(NSString *) path
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    [ref onDisconnectRemoveValueWithCompletionBlock:^(NSError * _Nullable error, FIRDatabaseReference * _Nonnull ref) {
        [self handleCallback:@"onDisconnectRemove" callback:callback databaseError:error];
    }];
}



RCT_EXPORT_METHOD(onDisconnectCancel:(NSString *) path
                  callback:(RCTResponseSenderBlock) callback)
{
    FIRDatabaseReference *ref = [self getPathRef:path];
    [ref cancelDisconnectOperationsWithCompletionBlock:^(NSError * _Nullable error, FIRDatabaseReference * _Nonnull ref) {
        [self handleCallback:@"onDisconnectCancel" callback:callback databaseError:error];
    }];
}

RCT_EXPORT_METHOD(goOffline)
{
    [FIRDatabase database].goOffline;
}

RCT_EXPORT_METHOD(goOnline)
{
    [FIRDatabase database].goOnline;
}

- (FIRDatabaseReference *) getPathRef:(NSString *) path
{
    return [[[FIRDatabase database] reference] child:path];
}

- (void) handleCallback:(NSString *) methodName
               callback:(RCTResponseSenderBlock) callback
          databaseError:(NSError *) databaseError
{
    if (databaseError != nil) {
        NSDictionary *evt = @{
                              @"code": [NSNumber numberWithInt:[databaseError code]],
                              @"details": [databaseError debugDescription],
                              @"message": [databaseError localizedDescription],
                              @"description": [databaseError description]
                              };
        callback(@[evt]);
    } else {
        callback(@[[NSNull null], @{
                       @"status": @"success",
                       @"method": methodName
                       }]);
    }
}

- (RNFirebaseDBReference *) getDBHandle:(NSNumber *) refId
                                   path:(NSString *) path
                              modifiers:(NSArray *) modifiers
{
    RNFirebaseDBReference *ref = [_dbReferences objectForKey:refId];

    if (ref == nil) {
        ref = [[RNFirebaseDBReference alloc] initWithPathAndModifiers:self
                                                             database:[FIRDatabase database]
                                                                refId:refId
                                                                 path:path
                                                            modifiers:modifiers];
        [_dbReferences setObject:ref forKey:refId];
    }
    return ref;
}

// Not sure how to get away from this... yet
- (NSArray<NSString *> *)supportedEvents {
    return @[DATABASE_DATA_EVENT, DATABASE_ERROR_EVENT, DATABASE_TRANSACTION_EVENT];
}


@end