#include "DebugPrint.h"
#include "CoreMinimal.h"

using DPrintCallback = DebugPrintControl::DPrintCallback;

//////////////////////////////////////////////////////////////
//
// DPrintState
// 
// The global state of the DPrint routine.  There is only
// ever one of these, and it is owned by DPrintAccess below.
//
//////////////////////////////////////////////////////////////

struct DPrintState {
	// True if buffering is enabled.
	bool Collect;

	// The array of buffered messages.
	TArray<FString> Messages;

	// The array of callback functions.
	TArray<DPrintCallback> Callbacks;
};

//////////////////////////////////////////////////////////////
//
// DPrintAccess
// 
// This class grants you safe access to the global state
// of the DPrint routine.  Constructing an object of
// class DPrintAccess will lock the global mutex and make
// sure that the DPrintState is initialized.  Then it will
// give you unrestricted access to the DPrintState through
// operator right arrow.
//
//////////////////////////////////////////////////////////////

class DPrintAccess {
private:
	// The Mutex that protects the global state.
	static FCriticalSection Mutex;

	// The Global State.  A pointer, to avoid static init issues.
	static DPrintState* State;

public:
	// Constructor.  Locks mutex and initializes state if necessary.
	DPrintAccess() {
		Mutex.Lock();
		if (State == nullptr) {
			State = new DPrintState;
			State->Collect = false;
		}
	}

	// Destructor.  Releases mutex.
	~DPrintAccess() {
		Mutex.Unlock();
	}

	// Access the DPrintState.
	DPrintState* operator ->() {
		return State;
	}
};

FCriticalSection DPrintAccess::Mutex;
DPrintState* DPrintAccess::State;


//////////////////////////////////////////////////////////////
//
// Namespace DebugPrint.
//
// This contains all the various versions of the DPrint routine.
//
//////////////////////////////////////////////////////////////

namespace DebugPrint {

	// DPrint. Invoke all the callbacks, and store the message.
	void DPrint(const FString& fs) {
		DPrintAccess state;
		for (DPrintCallback cb : state->Callbacks) {
			cb(fs);
		}
		if (state->Collect) {
			state->Messages.Emplace(fs);
		}
	}

	// Alternative interface to the dispatcher.
	void DPrint(const char* msg) {
		DPrint(FString(msg));
	}

	// Alternative interface to the dispatcher.
	void DPrint(const char* msg, size_t len) {
		DPrint(FString(len, (const UTF8CHAR*)msg));
	}

} // namespace DebugPrint

//////////////////////////////////////////////////////////////
//
// Namespace DebugPrintControl.
//
// Configuration and control for the DPrint routine.
// 
//////////////////////////////////////////////////////////////

namespace DebugPrintControl {

	// Register a callback.  Check for duplication.
	void RegisterCallback(DPrintCallback cb) {
		DPrintAccess state;
		for (DPrintCallback old : state->Callbacks) {
			if (cb == old) return;
		}
		state->Callbacks.Add(cb);
	}

	// Set the collection bit in the global state.
	void EnableCollection() {
		DPrintAccess state;
		state->Collect = true;
	}

	// Get the array of collected messages, if any.
	TArray<FString> GetStored() {
		DPrintAccess state;
		TArray<FString> result = std::move(state->Messages);
		state->Messages.Empty();
		return result;
	}
};

//////////////////////////////////////////////////////////////
//
// ConsoleOutput
//
// Storing the text that goes in the unreal console.
//
//////////////////////////////////////////////////////////////


void FlxConsoleOutput::Truncate() {
	int lines = 50;
	int csize = Content.Len();
	int total = 0;
	for (int i = csize - 1; i >= 0; i--) {
		if (Content[i] == '\n') {
			total += 1;
			if (total == lines) {
				Content = Content.RightChop(i + 1);
				return;
			}
		}
	}
}

bool FlxConsoleOutput::MaybeAppendNewline() {
	int csize = Content.Len();
	if ((csize > 0) && (Content[csize - 1] != '\n')) {
		Content += TEXT("\n");
		return true;
	}
	else {
		return false;
	}
}

bool FlxConsoleOutput::MaybeAppendText(const FString& text) {
	if (!text.IsEmpty()) {
		Content += text;
		return true;
	}
	else {
		return false;
	}
}

void FlxConsoleOutput::Append(const FString& text) {
	bool modified = MaybeAppendText(text);
	if (modified) {
		Dirty = true;
		Truncate();
	}
}

void FlxConsoleOutput::AppendLine(const FString& text) {
	bool modified = MaybeAppendNewline();
	modified |= MaybeAppendText(text);
	modified |= MaybeAppendNewline();
	if (modified) {
		Dirty = true;
		Truncate();
	}
}