#ifdef _DEBUG
#pragma comment(lib, "v8_monolith.lib")
#pragma comment(lib, "dbghelp.lib")

#else
#pragma comment(lib, "v8_monolith.release.lib")
#endif

#include <Windows.h>
#include <cassert>
#include <libplatform/libplatform.h>
#include <v8.h>
#include <v8pp/class.hpp>
#include <v8pp/module.hpp>
#include <thread>


v8::Global<v8::Function> function_pre_run;
v8::Global<v8::Function> function_post_run;

v8::Persistent<v8::Context> context;
v8::Isolate * isolate = nullptr;

const char* c_string(v8::String::Utf8Value& value) {
	return *value ? *value : "<string conversion failed>";
}

void report_exception(v8::TryCatch * try_catch)
{
	// Setup context...
	v8::Locker locker(isolate);
	v8::Isolate::Scope isolate_scope(isolate);
	v8::HandleScope handle_scope(isolate);
	v8::Context::Scope context_scope(context.Get(isolate));

	v8::String::Utf8Value exception(isolate, try_catch->Exception());
	const char* exception_string = c_string(exception);
	v8::Local<v8::Message> message = try_catch->Message();

	if (message.IsEmpty()) {
		// V8 didn't provide any extra information about this error; just
		// print the exception.
		fprintf(stderr, "%s\n", exception_string);
	}
	else {
		// Print (filename):(line number): (message).

		v8::Local<v8::Context> context(isolate->GetCurrentContext());

		int linenum = message->GetLineNumber(context).FromJust();

		fprintf(stderr, "%i: %s\n", linenum, exception_string);
		// Print line of source code.
		v8::String::Utf8Value sourceline(
			isolate, message->GetSourceLine(context).ToLocalChecked());
		const char* sourceline_string = c_string(sourceline);
		fprintf(stderr, "%s\n", sourceline_string);
		// Print wavy underline (GetUnderline is deprecated).
		int start = message->GetStartColumn(context).FromJust();
		for (int i = 0; i < start; i++) {
			fprintf(stderr, " ");
		}
		int end = message->GetEndColumn(context).FromJust();
		for (int i = start; i < end; i++) {
			fprintf(stderr, "^");
		}
		fprintf(stderr, "\n");
		v8::Local<v8::Value> stack_trace_string;
		if (try_catch->StackTrace(context).ToLocal(&stack_trace_string) &&
			stack_trace_string->IsString() &&
			v8::Local<v8::String>::Cast(stack_trace_string)->Length() > 0) {
			v8::String::Utf8Value stack_trace(isolate, stack_trace_string);
			const char* stack_trace_string = c_string(stack_trace);
			fprintf(stderr, "%s\n", stack_trace_string);
		}
	}
}


// Executes a string within the current v8 context.
bool execute_string(char * str, bool print_result, bool report_exceptions)
{
	// Setup context...
	v8::Locker locker(isolate);
	v8::Isolate::Scope isolate_scope(isolate);
	v8::HandleScope handle_scope(isolate);
	v8::Context::Scope context_scope(context.Get(isolate));

	// Enter the execution environment before evaluating any code.
	v8::Local<v8::String> name(v8::String::NewFromUtf8(isolate, "(shell)", v8::NewStringType::kNormal).ToLocalChecked());

	// Setup other related...
	v8::TryCatch try_catch(isolate);
	v8::ScriptOrigin origin(name);
	v8::Local<v8::Context> context(isolate->GetCurrentContext());
	v8::Local<v8::Script> script;

	// Setup our source...
	auto source = v8::String::NewFromUtf8(isolate, str, v8::NewStringType::kNormal).ToLocalChecked();

	// Empty out our function...
	function_pre_run.Empty();
	function_post_run.Empty();

	if (!v8::Script::Compile(context, source, &origin).ToLocal(&script))
	{
		// Print errors that happened during compilation.
		if (report_exceptions) report_exception(&try_catch);

		// Return false here...
		return false;
	}

	//////////////////////////////////////////////////

	v8::Local<v8::Value> result;

	if (!script->Run(context).ToLocal(&result))
	{
		assert(try_catch.HasCaught());

		// Print errors that happened during execution.
		if (report_exceptions) report_exception(&try_catch);

		return false;
	}

	//////////////////////////////////////////////////

	assert(!try_catch.HasCaught());
	if (print_result && !result->IsUndefined()) {
		// If all went well and the result wasn't undefined then print
		// the returned value.
		v8::String::Utf8Value str(isolate, result);
		const char* cstr = c_string(str);

		printf("%s\n", cstr);
	}

	return true;
}

void print(const v8::FunctionCallbackInfo<v8::Value>& args)
{
	// Setup context...
	v8::Locker locker(isolate);
	v8::Isolate::Scope isolate_scope(isolate);
	v8::HandleScope handle_scope(isolate);
	v8::Context::Scope context_scope(context.Get(isolate));

	bool first = true;
	for (int i = 0; i < args.Length(); i++)
	{
		v8::HandleScope handle_scope(isolate);
		if (first) {
			first = false;
		}
		else {
			fprintf(stderr, " ");
		}
		v8::String::Utf8Value str(isolate, args[i]);
		const char* cstr = c_string(str);
		fprintf(stderr, "%s", cstr);
	}
	fprintf(stderr, "\n");
	fflush(stdout);
}

void register_pre_run(const v8::FunctionCallbackInfo<v8::Value>& args)
{
	v8::Locker locker(isolate);
	v8::Isolate::Scope isolate_scope(isolate);
	v8::HandleScope handle_scope(isolate);
	v8::Context::Scope context_scope(context.Get(isolate));

	// Check if args given...
	if (args.Length() < 1) return;

	// Get our arguments...
	v8::Local<v8::Value> arg = args[0];

	// Check if arg is a function...
	if (!arg->IsFunction())
	{
		return;
	}

	// Reset our global function...
	function_pre_run.Reset(isolate, v8::Local<v8::Function>::Cast(arg));
}

void register_post_run(const v8::FunctionCallbackInfo<v8::Value>& args)
{
	v8::Locker locker(isolate);
	v8::Isolate::Scope isolate_scope(isolate);
	v8::HandleScope handle_scope(isolate);
	v8::Context::Scope context_scope(context.Get(isolate));

	// Check if args given...
	if (args.Length() < 1) return;

	// Get our arguments...
	v8::Local<v8::Value> arg = args[0];

	// Check if arg is a function...
	if (!arg->IsFunction())
	{
		return;
	}

	// Reset our global function...
	function_post_run.Reset(isolate, v8::Local<v8::Function>::Cast(arg));
}

void read_file(const char* name)
{
	v8::Locker locker(isolate);
	v8::Isolate::Scope isolate_scope(isolate);
	v8::HandleScope handle_scope(isolate);
	v8::Context::Scope context_scope(context.Get(isolate));

	FILE* file = fopen(name, "rb");
	if (file == NULL) return;

	fseek(file, 0, SEEK_END);
	size_t size = ftell(file);
	rewind(file);

	char* chars = new char[size + 1];
	chars[size] = '\0';
	for (size_t i = 0; i < size;) {
		i += fread(&chars[i], 1, size - i, file);
		if (ferror(file)) {
			fclose(file);
			return;
		}
	}
	fclose(file);

	if (!execute_string(chars, true, true)) {
		isolate->ThrowException(
			v8::String::NewFromUtf8(isolate, "Error executing file",
				v8::NewStringType::kNormal).ToLocalChecked());

	}
	delete[] chars;

	fprintf(stderr, "Loaded %s successfully...\n", name);
	fflush(stdout);
}

void load(const v8::FunctionCallbackInfo<v8::Value>& args) {
	v8::HandleScope handle_scope(isolate);

	for (int i = 0; i < args.Length(); i++)
	{
		v8::HandleScope handle_scope(isolate);
		v8::String::Utf8Value file(isolate, args[i]);
		if (*file == NULL) {
			isolate->ThrowException(
				v8::String::NewFromUtf8(isolate, "Error loading file",
					v8::NewStringType::kNormal).ToLocalChecked());
			return;
		}

		read_file(*file);
	}
}

v8::Local<v8::Context> create_shell_context()
{
	// Setup isolate locker...
	v8::Locker locker(isolate);
	v8::Isolate::Scope isolate_scope(isolate);

	// Create a template for the global object.
	v8::Local<v8::ObjectTemplate> global = v8::ObjectTemplate::New(isolate);

	// Bind the global 'print' function to the C++ Print callback.
	global->Set(v8::String::NewFromUtf8(isolate, "print").ToLocalChecked(), v8::FunctionTemplate::New(isolate, print));

	// Bind the global 'load' function to the C++ Load callback.
	global->Set(v8::String::NewFromUtf8(isolate, "load").ToLocalChecked(), v8::FunctionTemplate::New(isolate, load));

	////////////////////////////////

	// Bind the 'registerDraw' function
	global->Set(v8::String::NewFromUtf8(isolate, "registerPreRun").ToLocalChecked(),
		v8::FunctionTemplate::New(isolate, register_pre_run));

	// Bind the 'registerCreateMove' function
	global->Set(v8::String::NewFromUtf8(isolate, "registerPostRun").ToLocalChecked(),
		v8::FunctionTemplate::New(isolate, register_post_run));

	return v8::Context::New(isolate, NULL, global);
}

void run_shell()
{
	// Buffer size...
	static const int kBufferSize = 256;

	// While true loop...
	while (true)
	{
		char buffer[kBufferSize];
		fprintf(stderr, "> ");
		char* str = fgets(buffer, kBufferSize, stdin);
		if (str == NULL) break;

		//////////////////////////////////////////////

		// Execute string...
		execute_string(str, true, true);
	}

	// Print a newline...
	fprintf(stderr, "\n");
}


struct RequestManaged
{
	const char* uri;
	const char* ip;
};

extern "C"
{
	__declspec(dllimport) void call_pre_run(const char * serialized_request);
	__declspec(dllimport) void start_engine();
}


void call_pre_run(const char * serialized_request)
{
	// Check that isolate and the callback function is set...
	if (isolate && !function_pre_run.IsEmpty())
	{
		// Setup our lockers, isolate scope, and handle scope...
		v8::Locker locker(isolate);
		v8::Isolate::Scope isolate_scope(isolate);
		v8::HandleScope handle_scope(isolate);
		v8::Context::Scope context_scope(context.Get(isolate));

		// Parse our JSON string...
		auto request_object = v8::JSON::Parse(
			isolate->GetCurrentContext(),
			v8pp::to_v8(isolate, serialized_request, strlen(serialized_request))
		).ToLocalChecked();

		// Setup our arguments...
		v8::Local<v8::Value> argv[1] = { request_object };

		////////////////////////////////////////////////////

		// Local function...
		auto local_func = function_pre_run.Get(isolate);

		// Attempt to get our registered create move callback and call it...
		if (local_func->IsCallable())
			local_func->Call(isolate->GetCurrentContext(), v8::Null(isolate), 1, argv);
	}
}

void start_engine()
{
	std::thread engine([] {
		// Initialize...
		std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();

		v8::V8::InitializePlatform(platform.get());
		v8::V8::InitializeICU();
		v8::V8::Initialize();

		// Setup create params...
		v8::Isolate::CreateParams create_params;

		create_params.array_buffer_allocator = v8::ArrayBuffer::Allocator::NewDefaultAllocator();

		// Setup our isolate...
		isolate = v8::Isolate::New(create_params);

		{
			// Setup lockers...
			v8::Locker locker(isolate);
			v8::Isolate::Scope isolate_scope(isolate);
			v8::HandleScope handle_scope(isolate);

			// Setup our context...
			context.Reset(isolate, create_shell_context());
		}

		// Run our shell...
		run_shell();

		// Dispose our isolate...
		isolate->Dispose();

		// Dispose everything...
		v8::V8::Dispose();
		v8::V8::ShutdownPlatform();

		// Delete...
		delete create_params.array_buffer_allocator;
	});
	engine.detach();
}