package gr.cite.annotation.common.scope.fake;

import org.springframework.util.Assert;
import org.springframework.web.context.request.RequestAttributes;

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;

public class FakeRequestAttributes implements RequestAttributes {
	private Map<String, Object> requestAttributeMap = new HashMap<>();
	private final Map<String, Runnable> requestDestructionCallbacks = new LinkedHashMap<>(8);
	private volatile boolean requestActive = true;

	@Override
	public Object getAttribute(String name, int scope) {
		if (scope == RequestAttributes.SCOPE_REQUEST) {
			if (!isRequestActive()) {
				throw new IllegalStateException("Cannot ask for request attribute - request is not active anymore!");
			}
			return this.requestAttributeMap.get(name);
		} else {
			throw new IllegalStateException("Only " + RequestAttributes.SCOPE_REQUEST + " allowed for " + FakeRequestAttributes.class.getSimpleName());
		}
	}

	@Override
	public void setAttribute(String name, Object value, int scope) {
		if (scope == RequestAttributes.SCOPE_REQUEST) {
			if (!isRequestActive()) {
				throw new IllegalStateException("Cannot set request attribute - request is not active anymore!");
			}
			this.requestAttributeMap.put(name, value);
		} else {
			throw new IllegalStateException("Only " + RequestAttributes.SCOPE_REQUEST + " allowed for " + FakeRequestAttributes.class.getSimpleName());
		}
	}

	@Override
	public void removeAttribute(String name, int scope) {
		if (scope == RequestAttributes.SCOPE_REQUEST) {
			if (isRequestActive()) {
				removeRequestDestructionCallback(name);
				this.requestAttributeMap.remove(name);
			}
		} else {
			throw new IllegalStateException("Only " + RequestAttributes.SCOPE_REQUEST + " allowed for " + FakeRequestAttributes.class.getSimpleName());
		}
	}

	@Override
	public String[] getAttributeNames(int scope) {
		if (scope == RequestAttributes.SCOPE_REQUEST) {
			if (!isRequestActive()) {
				throw new IllegalStateException("Cannot ask for request attributes - request is not active anymore!");
			}
			return this.requestAttributeMap.keySet().toArray(new String[0]);
		} else {
			throw new IllegalStateException("Only " + RequestAttributes.SCOPE_REQUEST + " allowed for " + FakeRequestAttributes.class.getSimpleName());
		}
		//return new String[0];
	}

	@Override
	public void registerDestructionCallback(String name, Runnable callback, int scope) {
		if (scope == SCOPE_REQUEST) {
			registerRequestDestructionCallback(name, callback);
		} else {
			throw new IllegalStateException("Only " + RequestAttributes.SCOPE_REQUEST + " allowed for " + FakeRequestAttributes.class.getSimpleName());
		}
	}

	protected final void registerRequestDestructionCallback(String name, Runnable callback) {
		Assert.notNull(name, "Name must not be null");
		Assert.notNull(callback, "Callback must not be null");
		synchronized (this.requestDestructionCallbacks) {
			this.requestDestructionCallbacks.put(name, callback);
		}
	}

	@Override
	public Object resolveReference(String key) {
		// Not supported
		return null;
	}

	@Override
	public String getSessionId() {
		return null;
	}

	@Override
	public Object getSessionMutex() {
		return null;
	}

	public void requestCompleted() {
		executeRequestDestructionCallbacks();
		for (String name : getAttributeNames(RequestAttributes.SCOPE_REQUEST)) {
			this.removeAttribute(name, RequestAttributes.SCOPE_REQUEST);
		}
		this.requestActive = false;
	}

	private final boolean isRequestActive() {
		return this.requestActive;
	}


	private final void removeRequestDestructionCallback(String name) {
		Assert.notNull(name, "Name must not be null");
		synchronized (this.requestDestructionCallbacks) {
			this.requestDestructionCallbacks.remove(name);
		}
	}

	private void executeRequestDestructionCallbacks() {
		synchronized (this.requestDestructionCallbacks) {
			for (Runnable runnable : this.requestDestructionCallbacks.values()) {
				runnable.run();
			}
			this.requestDestructionCallbacks.clear();
		}
	}
}