#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

extern NSString * const BTJSONErrorDomain;

typedef NS_ENUM(NSInteger, BTJSONErrorCode) {
    BTJSONErrorValueUnknown = 0,
    BTJSONErrorValueInvalid = 1,
    BTJSONErrorAccessInvalid = 2,
};

/**
 @brief A type-safe wrapper around JSON

 @see http://www.json.org/

 @discussion The primary goal of this class is to two-fold: (1) prevent bugs by staying true to JSON (json.org)
 rather than interpreting it in mysterious ways; (2) prevent bugs by making JSON interpretation
 as un-surprising as possible.

 Most notably, type casting occurs via the as* nullable methods; errors are deferred and can be checked explicitly using isError and asError.
 
 @code
 ## Example Data:
    {
      "foo": "bar",
      "baz": [1, 2, 3]
    }

 ## Example Usage:

    let json : BTJSON = BTJSON(data:data);
    json.isError  // false
    json.isObject // true
    json.isNumber // false
    json.asObject // self
    json["foo"]   // JSON(@"bar")
    json["foo"].isString // true
    json["foo"].asString // @"bar"
    json["baz"].asString // null
    json["baz"]["quux"].isError // true
    json["baz"]["quux"].asError // NSError(domain: BTJSONErrorDomain, code: BTJSONErrorCodeTypeInvalid)
    json["baz"][0].asError // null
    json["baz"][0].asInteger //
    json["random"]["nested"]["things"][3].isError // true

    let json : BTJSON = BTJSON() // json.asJson => {}
    json["foo"][0] = "bar" // json.asJSON => { "foo": ["bar"] }
    json["baz"] = [ 1, 2, 3 ] // json.asJSON => { "foo": ["bar"], "baz": [1,2,3] }
    json["quux"] = NSSet() // json.isError => true, json.asJSON => throws NSError(domain: BTJSONErrorDomain, code: BTJSONErrorInvalidData)
 @endcode
*/
@interface BTJSON : NSObject

- (instancetype)init NS_DESIGNATED_INITIALIZER;

- (instancetype)initWithValue:(id)value;

- (instancetype)initWithData:(NSData *)data;

/// @name Subscripting

/**
 @brief Indexes into the JSON as if the current value is an object

 @discussion Notably, this method will always return successfully; however, if the value is not an object, the JSON will wrap an error.
*/
- (id)objectForKeyedSubscript:(NSString *)key;

/**
 @brief Indexes into the JSON as if the current value is an array

 @discussion Notably, this method will always return successfully; however, if the value is not an array, the JSON will wrap an error.
*/
- (BTJSON *)objectAtIndexedSubscript:(NSUInteger)idx;

/// @name Validity Checks

@property (nonatomic, assign, readonly) BOOL isError;

- (nullable NSError *)asError;

/// @name Generating JSON

- (nullable NSData *)asJSONAndReturnError:(NSError **)error;
- (nullable NSString *)asPrettyJSONAndReturnError:(NSError **)error;

/// @name JSON Type Casts

- (nullable NSString *)asString;

- (nullable NSArray<BTJSON *> *)asArray;

- (nullable NSDecimalNumber *)asNumber;

/// @name JSON Extension Type Casts

- (nullable NSURL *)asURL;

- (nullable NSArray<NSString *> *)asStringArray;

- (nullable NSDictionary *)asDictionary;

- (NSInteger)asIntegerOrZero;

- (NSInteger)asEnum:(NSDictionary *)mapping orDefault:(NSInteger)defaultValue;

/// @name JSON Type Checks

@property (nonatomic, assign, readonly) BOOL isString;

@property (nonatomic, assign, readonly) BOOL isNumber;

@property (nonatomic, assign, readonly) BOOL isArray;

@property (nonatomic, assign, readonly) BOOL isObject;

@property (nonatomic, assign, readonly) BOOL isTrue;

@property (nonatomic, assign, readonly) BOOL isFalse;

@property (nonatomic, assign, readonly) BOOL isNull;

@end

NS_ASSUME_NONNULL_END