// Copyright 2018-present 650 Industries. All rights reserved.

#import <jsi/jsi.h>

#if __has_include(<reacthermes/HermesExecutorFactory.h>)
#import <reacthermes/HermesExecutorFactory.h>
#else
#import <jsi/JSCRuntime.h>
#endif

#import <ExpoModulesCore/EXJavaScriptRuntime.h>
#import <ExpoModulesCore/ExpoModulesHostObject.h>
#import <ExpoModulesCore/EXJSIUtils.h>
#import <ExpoModulesCore/EXJSIConversions.h>
#import <ExpoModulesCore/Swift.h>


/**
 Property name of the main object in the Expo JS runtime.
 */
static NSString *mainObjectPropertyName = @"expo";

@implementation EXJavaScriptRuntime {
  std::shared_ptr<jsi::Runtime> _runtime;
  std::shared_ptr<react::CallInvoker> _jsCallInvoker;
  EXJavaScriptObject *_mainObject;
}

/**
 Initializes a runtime that is independent from React Native and its runtime initialization.
 This flow is mostly intended for tests. The JS call invoker is unavailable thus calling async functions is not supported.
 TODO: Implement the call invoker when it becomes necessary.
 */
- (nonnull instancetype)init
{
  if (self = [super init]) {
#if __has_include(<reacthermes/HermesExecutorFactory.h>)
    _runtime = facebook::hermes::makeHermesRuntime();
#else
    _runtime = jsc::makeJSCRuntime();
#endif
    _jsCallInvoker = nil;
    [self initializeMainObject];
  }
  return self;
}

- (nonnull instancetype)initWithRuntime:(nonnull jsi::Runtime *)runtime
                            callInvoker:(std::shared_ptr<react::CallInvoker>)callInvoker
{
  if (self = [super init]) {
    // Creating a shared pointer that points to the runtime but doesn't own it, thus doesn't release it.
    // In this code flow, the runtime should be owned by something else like the RCTBridge.
    // See explanation for constructor (8): https://en.cppreference.com/w/cpp/memory/shared_ptr/shared_ptr
    _runtime = std::shared_ptr<jsi::Runtime>(std::shared_ptr<jsi::Runtime>(), runtime);
    _jsCallInvoker = callInvoker;
    [self initializeMainObject];
  }
  return self;
}

- (nonnull jsi::Runtime *)get
{
  return _runtime.get();
}

- (std::shared_ptr<react::CallInvoker>)callInvoker
{
  return _jsCallInvoker;
}

- (nonnull EXJavaScriptObject *)createObject
{
  auto jsObjectPtr = std::make_shared<jsi::Object>(*_runtime);
  return [[EXJavaScriptObject alloc] initWith:jsObjectPtr runtime:self];
}

- (nonnull EXJavaScriptObject *)createHostObject:(std::shared_ptr<jsi::HostObject>)jsiHostObjectPtr
{
  auto jsObjectPtr = std::make_shared<jsi::Object>(jsi::Object::createFromHostObject(*_runtime, jsiHostObjectPtr));
  return [[EXJavaScriptObject alloc] initWith:jsObjectPtr runtime:self];
}

- (nonnull EXJavaScriptObject *)global
{
  auto jsGlobalPtr = std::make_shared<jsi::Object>(_runtime->global());
  return [[EXJavaScriptObject alloc] initWith:jsGlobalPtr runtime:self];
}

- (nonnull EXJavaScriptObject *)mainObject
{
  return _mainObject;
}

- (nonnull EXJavaScriptObject *)createSyncFunction:(nonnull NSString *)name
                                         argsCount:(NSInteger)argsCount
                                             block:(nonnull JSSyncFunctionBlock)block
{
  JSHostFunctionBlock hostFunctionBlock = ^jsi::Value(
    jsi::Runtime &runtime,
    std::shared_ptr<react::CallInvoker> callInvoker,
    EXJavaScriptValue * _Nonnull thisValue,
    NSArray<EXJavaScriptValue *> * _Nonnull arguments) {
      NSError *error;
      id result = block(thisValue, arguments, &error);

      if (error == nil) {
        return expo::convertObjCObjectToJSIValue(runtime, result);
      } else {
        throw jsi::JSError(runtime, [error.userInfo[@"message"] UTF8String]);
      }
    };
  return [self createHostFunction:name argsCount:argsCount block:hostFunctionBlock];
}

- (nonnull EXJavaScriptObject *)createAsyncFunction:(nonnull NSString *)name
                                          argsCount:(NSInteger)argsCount
                                              block:(nonnull JSAsyncFunctionBlock)block
{
  JSHostFunctionBlock hostFunctionBlock = ^jsi::Value(
    jsi::Runtime &runtime,
    std::shared_ptr<react::CallInvoker> callInvoker,
    EXJavaScriptValue * _Nonnull thisValue,
    NSArray<EXJavaScriptValue *> * _Nonnull arguments) {
      if (!callInvoker) {
        // In mocked environment the call invoker may be null so it's not supported to call async functions.
        // Testing async functions is a bit more complicated anyway. See `init` description for more.
        throw jsi::JSError(runtime, "Calling async functions is not supported when the call invoker is unavailable");
      }
      // The function that is invoked as a setup of the EXJavaScript `Promise`.
      auto promiseSetup = [callInvoker, block, thisValue, arguments](jsi::Runtime &runtime, std::shared_ptr<Promise> promise) {
        expo::callPromiseSetupWithBlock(runtime, callInvoker, promise, ^(RCTPromiseResolveBlock resolver, RCTPromiseRejectBlock rejecter) {
          block(thisValue, arguments, resolver, rejecter);
        });
      };
      return createPromiseAsJSIValue(runtime, promiseSetup);
    };
  return [self createHostFunction:name argsCount:argsCount block:hostFunctionBlock];
}

#pragma mark - Classes

- (nonnull EXJavaScriptObject *)createClass:(nonnull NSString *)name
                                constructor:(nonnull ClassConstructorBlock)constructor
{
  expo::ClassConstructor jsConstructor = [self, constructor](jsi::Runtime &runtime, const jsi::Value &thisValue, const jsi::Value *args, size_t count) {
    std::shared_ptr<jsi::Object> thisPtr = std::make_shared<jsi::Object>(thisValue.asObject(runtime));
    EXJavaScriptObject *caller = [[EXJavaScriptObject alloc] initWith:thisPtr runtime:self];
    NSArray<EXJavaScriptValue *> *arguments = expo::convertJSIValuesToNSArray(self, args, count);

    constructor(caller, arguments);
  };
  std::shared_ptr<jsi::Function> klass = expo::createClass(*_runtime, [name UTF8String], jsConstructor);
  return [[EXJavaScriptObject alloc] initWith:klass runtime:self];
}

#pragma mark - Script evaluation

- (nonnull EXJavaScriptValue *)evaluateScript:(nonnull NSString *)scriptSource
{
  std::shared_ptr<jsi::StringBuffer> scriptBuffer = std::make_shared<jsi::StringBuffer>([scriptSource UTF8String]);
  std::shared_ptr<jsi::Value> result;

  try {
    result = std::make_shared<jsi::Value>(_runtime->evaluateJavaScript(scriptBuffer, "<<evaluated>>"));
  } catch (jsi::JSError &error) {
    NSString *reason = [NSString stringWithUTF8String:error.getMessage().c_str()];
    NSString *stack = [NSString stringWithUTF8String:error.getStack().c_str()];

    @throw [NSException exceptionWithName:@"ScriptEvaluationException" reason:reason userInfo:@{
      @"message": reason,
      @"stack": stack,
    }];
  } catch (jsi::JSIException &error) {
    NSString *reason = [NSString stringWithUTF8String:error.what()];
    
    @throw [NSException exceptionWithName:@"ScriptEvaluationException" reason:reason userInfo:@{
      @"message": reason
    }];
  }
  return [[EXJavaScriptValue alloc] initWithRuntime:self value:result];
}

#pragma mark - Private

- (void)initializeMainObject
{
  if (!_mainObject) {
    // Add the main object to the runtime (`global.expo`).
    _mainObject = [self createObject];
    [[self global] defineProperty:mainObjectPropertyName value:_mainObject options:EXJavaScriptObjectPropertyDescriptorEnumerable];
  }
}

- (nonnull EXJavaScriptObject *)createHostFunction:(nonnull NSString *)name
                                         argsCount:(NSInteger)argsCount
                                             block:(nonnull JSHostFunctionBlock)block
{
  jsi::PropNameID propNameId = jsi::PropNameID::forAscii(*_runtime, [name UTF8String], [name length]);
  std::weak_ptr<react::CallInvoker> weakCallInvoker = _jsCallInvoker;
  jsi::HostFunctionType function = [weakCallInvoker, block, self](jsi::Runtime &runtime, const jsi::Value &thisVal, const jsi::Value *args, size_t count) -> jsi::Value {
    // Theoretically should check here whether the call invoker isn't null, but in mocked environment
    // there is no need to care about that for synchronous calls, so it's ensured in `createAsyncFunction` instead.
    auto callInvoker = weakCallInvoker.lock();
    NSArray<EXJavaScriptValue *> *arguments = expo::convertJSIValuesToNSArray(self, args, count);
    std::shared_ptr<jsi::Value> thisValPtr = std::make_shared<jsi::Value>(runtime, std::move(thisVal));
    EXJavaScriptValue *thisValue = [[EXJavaScriptValue alloc] initWithRuntime:self value:thisValPtr];

    return block(runtime, callInvoker, thisValue, arguments);
  };
  std::shared_ptr<jsi::Object> fnPtr = std::make_shared<jsi::Object>(jsi::Function::createFromHostFunction(*_runtime, propNameId, (unsigned int)argsCount, function));
  return [[EXJavaScriptObject alloc] initWith:fnPtr runtime:self];
}

@end