package de.opcua.app.opc;

import de.opcua.app.model.TreeNodeRef;
import org.eclipse.milo.opcua.sdk.client.OpcUaClient;
import org.eclipse.milo.opcua.stack.core.Identifiers;
import org.eclipse.milo.opcua.stack.core.types.builtin.NodeId;
import org.eclipse.milo.opcua.stack.core.types.builtin.Variant;
import org.eclipse.milo.opcua.stack.core.types.structured.ReferenceDescription;
import org.eclipse.milo.opcua.stack.core.types.enumerated.TimestampsToReturn;

import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

public final class OpcUaService {

    private volatile OpcUaClient client;

    // ------------------------------------------------------------
    // CONNECTION
    // ------------------------------------------------------------

    public boolean isConnected() {
        return client != null;
    }

    public CompletableFuture<Void> connect(String endpointUrl) {
        try {
            OpcUaClient c = OpcUaClient.create(endpointUrl);
            this.client = c;
            return c.connect().thenApply(ignored -> null);
        } catch (Exception e) {
            CompletableFuture<Void> failed = new CompletableFuture<>();
            failed.completeExceptionally(e);
            return failed;
        }
    }

    public CompletableFuture<Void> disconnect() {
        OpcUaClient c = client;
        client = null;
        if (c == null) return CompletableFuture.completedFuture(null);
        return c.disconnect().thenApply(ignored -> null);
    }

    // ------------------------------------------------------------
    // BROWSE — async (für GUI)
    // ------------------------------------------------------------

    public CompletableFuture<List<TreeNodeRef>> browseRoot() {
        return browseNode(Identifiers.RootFolder);
    }

    public CompletableFuture<List<TreeNodeRef>> browse(String nodeId) {
        return browseNode(NodeId.parse(nodeId));
    }

    private CompletableFuture<List<TreeNodeRef>> browseNode(NodeId nodeId) {
        try {
            List<ReferenceDescription> refs = client.getAddressSpace().browse(nodeId);
            return CompletableFuture.completedFuture(mapRefs(refs));
        } catch (Exception e) {
            CompletableFuture<List<TreeNodeRef>> f = new CompletableFuture<>();
            f.completeExceptionally(e);
            return f;
        }
    }

    // ------------------------------------------------------------
    // BROWSE — synchron (nur für Digital Twin Build Thread!)
    // ------------------------------------------------------------

    public List<TreeNodeRef> browseRootSync() throws Exception {
        return browseNodeSync(Identifiers.RootFolder);
    }

    public List<TreeNodeRef> browseSync(String nodeId) throws Exception {
        return browseNodeSync(NodeId.parse(nodeId));
    }

    private List<TreeNodeRef> browseNodeSync(NodeId nodeId) throws Exception {
        List<ReferenceDescription> refs = client.getAddressSpace().browse(nodeId);
        return mapRefs(refs);
    }

    // ── shared mapping ───────────────────────────────────────────────────────
    private List<TreeNodeRef> mapRefs(List<ReferenceDescription> refs) {
        return refs.stream()
                .map(r -> {
                    String displayName = r.getDisplayName() != null
                            ? r.getDisplayName().getText()
                            : r.getBrowseName().getName();
                    String nodeClass = r.getNodeClass() != null
                            ? r.getNodeClass().name() : "Unknown";
                    String dataType = "Unknown";
                    try {
                        if (r.getTypeDefinition() != null)
                            dataType = r.getTypeDefinition().toParseableString();
                    } catch (Exception ignored) {}
                    String referenceTypeId = null;
                    try {
                        if (r.getReferenceTypeId() != null)
                            referenceTypeId = r.getReferenceTypeId().toParseableString();
                    } catch (Exception ignored) {}
                    return new TreeNodeRef(
                            displayName,
                            r.getNodeId().toParseableString(),
                            r.getBrowseName().getName(),
                            nodeClass, dataType, "ReadWrite", referenceTypeId);
                })
                .collect(Collectors.toList());
    }

    // ------------------------------------------------------------
    // READ VALUE — async (für GUI)
    // ------------------------------------------------------------

    public CompletableFuture<String> readValue(String nodeId) {
        NodeId id = NodeId.parse(nodeId);
        return client.readValue(0, TimestampsToReturn.Neither, id)
                .thenApply(dv -> {
                    if (dv == null || dv.getValue() == null) return "<null>";
                    Object v = dv.getValue().getValue();
                    return v == null ? "<null>" : v.toString();
                });
    }

    // ------------------------------------------------------------
    // READ VALUE — synchron (nur für Digital Twin Build Thread!)
    // ------------------------------------------------------------

    public String readValueSync(String nodeId) throws Exception {
        NodeId id = NodeId.parse(nodeId);
        var dv = client.readValue(0, TimestampsToReturn.Neither, id)
                .get(5, TimeUnit.SECONDS);
        if (dv == null || dv.getValue() == null) return "<null>";
        Object v = dv.getValue().getValue();
        return v == null ? "<null>" : v.toString();
    }

    // ------------------------------------------------------------
    // WRITE VALUE
    // ------------------------------------------------------------

    public CompletableFuture<Boolean> writeValue(String nodeId, Object value) {
        NodeId id = NodeId.parse(nodeId);
        try {
            Variant variant = convertToVariant(value);
            org.eclipse.milo.opcua.stack.core.types.builtin.DataValue dataValue =
                new org.eclipse.milo.opcua.stack.core.types.builtin.DataValue(variant);

            return client.writeValue(id, dataValue)
                    .thenApply(statusCode -> {
                        if (statusCode != null && statusCode.isGood()) {
                            return true;
                        }
                        System.err.println("Write failed for " + nodeId + ": " + statusCode);
                        return false;
                    })
                    .exceptionally(ex -> {
                        System.err.println("Write exception for " + nodeId + ": " + ex.getMessage());
                        return false;
                    });
        } catch (Exception e) {
            CompletableFuture<Boolean> failed = new CompletableFuture<>();
            failed.completeExceptionally(e);
            return failed;
        }
    }

    private Variant convertToVariant(Object value) {
        if (value == null) return new Variant(null);
        if (value instanceof String) {
            String str = (String) value;
            try {
                return str.contains(".")
                        ? new Variant(Double.parseDouble(str))
                        : new Variant(Integer.parseInt(str));
            } catch (NumberFormatException e) {
                return new Variant(str);
            }
        } else if (value instanceof Integer) return new Variant((Integer) value);
        else if (value instanceof Long)      return new Variant((Long) value);
        else if (value instanceof Double)    return new Variant((Double) value);
        else if (value instanceof Float)     return new Variant((Float) value);
        else if (value instanceof Boolean)   return new Variant((Boolean) value);
        else if (value instanceof Short)     return new Variant((Short) value);
        else if (value instanceof Byte)      return new Variant((Byte) value);
        return new Variant(value.toString());
    }
}