package com.battery.device.bts;

import java.io.StringReader;
import java.math.BigDecimal;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.helpers.DefaultHandler;
import com.battery.device.api.model.ChannelIdentity;
import com.battery.device.api.model.DeviceConnectionStatus;
import com.battery.device.api.model.DetectedChannel;
import com.battery.device.api.model.DetectedDeviceMetadata;
import com.battery.device.api.model.DeviceWorkStatus;
import com.battery.device.api.model.Measurement;
import com.battery.device.api.model.PlannedStep;
import com.battery.device.api.model.RealtimeSnapshot;

public final class BtsXmlCodec
{
    private static final DateTimeFormatter BTS_TIME = DateTimeFormatter.ofPattern("yyyy-MM-dd HH.mm.ss");
    private static final Set<String> SNAPSHOT_ATTRIBUTES = Set.of(
            "dev", "cycle_id", "step_id", "step_type", "workstatus", "barcode", "current", "voltage",
            "capacity", "energy", "totaltime", "relativetime", "auxtemp", "auxvol", "open_or_close", "log_code",
            "device_time", "deviceTime", "time", "atime", "testtime");

    private final String adapterCode;
    private final ZoneId deviceZone;

    public BtsXmlCodec(String adapterCode, ZoneId deviceZone)
    {
        if (adapterCode == null || adapterCode.isBlank()) throw new IllegalArgumentException("adapterCode must not be blank");
        this.adapterCode = adapterCode.trim();
        this.deviceZone = deviceZone;
    }

    public String getDeviceInfoRequest()
    {
        return envelope("<cmd>getdevinfo</cmd>");
    }

    public String inquireRequest(Set<ChannelIdentity> channels, boolean includeBarcode)
    {
        StringBuilder list = new StringBuilder("<cmd>inquire</cmd><list count=\"").append(channels.size()).append("\">");
        for (ChannelIdentity channel : channels)
        {
            requireOwned(channel);
            list.append("<inquire ip=\"127.0.0.1\" devtype=\"").append(channel.devtype())
                    .append("\" devid=\"").append(channel.devid())
                    .append("\" subdevid=\"").append(channel.subdevid())
                    .append("\" chlid=\"").append(channel.chlid())
                    .append("\" aux=\"0\" barcode=\"").append(includeBarcode ? 1 : 0).append("\">true</inquire>");
        }
        return envelope(list.append("</list>").toString());
    }



    public List<DetectedChannel> parseDeviceInfo(String xml)
    {
        Document document = parse(xml, "getdevinfo_resp");
        NodeList nodes = firstElement(document, "middle").getElementsByTagName("channel");
        List<DetectedChannel> channels = new ArrayList<>(nodes.getLength());
        for (int i = 0; i < nodes.getLength(); i++)
        {
            Element element = (Element) nodes.item(i);
            int chlid = integerAttribute(element, element.hasAttribute("Channelid") ? "Channelid" : "chlid");
            ChannelIdentity identity = new ChannelIdentity(adapterCode, integerAttribute(element, "devtype"),
                    integerAttribute(element, "devid"), integerAttribute(element, "subdevid"), chlid);
            channels.add(new DetectedChannel(identity, requiredAttribute(element, "ip"),
                    booleanText(element.getTextContent(), "available"),
                    new DetectedDeviceMetadata(optionalAttribute(element, "name"),
                            optionalAttribute(element, "manufacturer"), optionalAttribute(element, "model"),
                            optionalAttribute(element, "mac"))));
        }
        return List.copyOf(channels);
    }

    public Map<ChannelIdentity, RealtimeSnapshot> parseSnapshots(String xml, Instant receivedAt)
    {
        Document document = parse(xml, "inquire_resp");
        NodeList nodes = firstElement(document, "list").getElementsByTagName("inquire");
        Map<ChannelIdentity, RealtimeSnapshot> snapshots = new LinkedHashMap<>();
        for (int i = 0; i < nodes.getLength(); i++)
        {
            Element element = (Element) nodes.item(i);
            String[] device = requiredAttribute(element, "dev").split("-");
            if (device.length < 4)
                throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                        "Invalid BTS dev identity: " + element.getAttribute("dev"));
            ChannelIdentity identity = new ChannelIdentity(adapterCode, integer(device[0], "devtype"), integer(device[1], "devid"),
                    integer(device[2], "subdevid"), integer(device[3], "chlid"));
            Instant deviceTime = optionalDeviceTime(element);
            snapshots.put(identity, new RealtimeSnapshot(identity,
                    DeviceWorkStatus.fromBts(element.getAttribute("workstatus")), optionalInteger(element, "cycle_id"),
                    optionalInteger(element, "step_id"), optionalAttribute(element, "step_type"), optionalAttribute(element, "barcode"),
                    optionalDecimal(element, "current"), optionalDecimal(element, "voltage"), optionalDecimal(element, "capacity"),
                    optionalDecimal(element, "energy"), optionalLong(element, "totaltime"), optionalLong(element, "relativetime"),
                    optionalAttribute(element, "log_code"), receivedAt, dynamicMeasurements(element, SNAPSHOT_ATTRIBUTES),
                    DeviceConnectionStatus.ONLINE, deviceTime, parsePlannedSteps(element), null));
        }
        return Map.copyOf(snapshots);
    }



    private Document parse(String xml, String expectedCommand)
    {
        try
        {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
            factory.setFeature("http://xml.org/sax/features/external-general-entities", false);
            factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
            factory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
            factory.setAttribute(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");
            factory.setXIncludeAware(false);
            factory.setExpandEntityReferences(false);
            DocumentBuilder builder = factory.newDocumentBuilder();
            builder.setErrorHandler(new DefaultHandler());
            Document document = builder.parse(new InputSource(new StringReader(xml)));
            String command = firstElement(document, "cmd").getTextContent().trim();
            if (!expectedCommand.equals(command))
                throw new BtsProtocolException(BtsProtocolException.Reason.UNEXPECTED_COMMAND,
                        "Expected BTS command " + expectedCommand + " but received " + command);
            return document;
        }
        catch (BtsProtocolException ex)
        {
            throw ex;
        }
        catch (Exception ex)
        {
            throw new BtsProtocolException(BtsProtocolException.Reason.MALFORMED_XML,
                    "Invalid BTS XML response", ex);
        }
    }

    private Map<String, Measurement> dynamicMeasurements(Element element, Set<String> knownAttributes)
    {
        Map<String, Measurement> measurements = new HashMap<>();
        NamedNodeMap attributes = element.getAttributes();
        for (int i = 0; i < attributes.getLength(); i++)
        {
            Node attribute = attributes.item(i);
            if (!knownAttributes.contains(attribute.getNodeName()))
            {
                BigDecimal value = decimal(attribute.getNodeValue(), attribute.getNodeName());
                measurements.put(attribute.getNodeName(), new Measurement(attribute.getNodeName(), value, null, "", "AUX"));
            }
        }
        NodeList dbcNodes = element.getElementsByTagName("DBC");
        for (int i = 0; i < dbcNodes.getLength(); i++)
        {
            Element dbc = (Element) dbcNodes.item(i);
            String code = "DBC:" + requiredAttribute(dbc, "message_name") + ":" + requiredAttribute(dbc, "signal_name");
            measurements.put(code, new Measurement(code, decimal(requiredAttribute(dbc, "value"), code), null,
                    optionalAttribute(dbc, "unit"), "DBC"));
        }
        return Map.copyOf(measurements);
    }

    private Instant parseDeviceTime(String value)
    {
        try
        {
            // BTS 时间不带时区，按适配器配置的现场时区解释后统一转换为 UTC 时间点。
            try
            {
                return Instant.parse(value);
            }
            catch (DateTimeParseException ignored)
            {
                return LocalDateTime.parse(value, BTS_TIME).atZone(deviceZone).toInstant();
            }
        }
        catch (DateTimeParseException ex)
        {
            throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                    "Invalid BTS device time: " + value, ex);
        }
    }

    private Instant optionalDeviceTime(Element element)
    {
        for (String name : List.of("device_time", "deviceTime", "time", "atime", "testtime"))
        {
            String value = optionalAttribute(element, name);
            if (value != null) return parseDeviceTime(value);
        }
        return null;
    }

    private List<PlannedStep> parsePlannedSteps(Element channel)
    {
        List<PlannedStep> steps = new ArrayList<>();
        NodeList nodes = channel.getElementsByTagName("plannedStep");
        if (nodes.getLength() == 0) nodes = channel.getElementsByTagName("planStep");
        if (nodes.getLength() == 0) nodes = channel.getElementsByTagName("step");
        for (int i = 0; i < nodes.getLength(); i++)
        {
            Element step = (Element) nodes.item(i);
            String number = firstOptionalAttribute(step, "step_no", "stepNo", "step_id", "stepid", "id");
            String type = firstOptionalAttribute(step, "step_type", "stepType", "steptype", "type");
            if (number == null || type == null) continue;
            steps.add(new PlannedStep(integer(number, "planned step number"), type,
                    firstOptionalAttribute(step, "name", "step_name", "stepName"),
                    optionalDecimalFromNames(step, "target_voltage", "targetVoltage", "voltage"),
                    optionalDecimalFromNames(step, "target_current", "targetCurrent", "current"),
                    optionalLongFromNames(step, "duration_seconds", "durationSeconds", "duration")));
        }
        return List.copyOf(steps);
    }

    private static String firstOptionalAttribute(Element element, String... names)
    {
        for (String name : names)
        {
            String value = optionalAttribute(element, name);
            if (value != null) return value;
        }
        return null;
    }

    private static BigDecimal optionalDecimalFromNames(Element element, String... names)
    {
        String value = firstOptionalAttribute(element, names);
        return value == null ? null : decimal(value, names[0]);
    }

    private static Long optionalLongFromNames(Element element, String... names)
    {
        String value = firstOptionalAttribute(element, names);
        if (value == null) return null;
        try { return Long.parseLong(value); }
        catch (NumberFormatException ex)
        {
            throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                    "Invalid planned step duration: " + value, ex);
        }
    }

    private void requireOwned(ChannelIdentity channel)
    {
        if (!adapterCode.equals(channel.adapterCode())) throw new IllegalArgumentException("Channel belongs to another adapter");
    }

    private static String envelope(String body)
    {
        return "<?xml version=\"1.0\" encoding=\"UTF-8\"?><bts version=\"1.0\">" + body + "</bts>";
    }

    private static String escape(String value)
    {
        return value.replace("&", "&amp;").replace("\"", "&quot;").replace("<", "&lt;").replace(">", "&gt;");
    }

    private static Element firstElement(Document document, String tag)
    {
        NodeList elements = document.getElementsByTagName(tag);
        if (elements.getLength() == 0)
            throw new BtsProtocolException(BtsProtocolException.Reason.MISSING_FIELD, "Missing BTS element: " + tag);
        return (Element) elements.item(0);
    }

    private static String requiredAttribute(Element element, String name)
    {
        String value = element.getAttribute(name);
        if (value == null || value.isBlank())
            throw new BtsProtocolException(BtsProtocolException.Reason.MISSING_FIELD, "Missing BTS attribute: " + name);
        return value.trim();
    }

    private static String optionalAttribute(Element element, String name)
    {
        String value = element.getAttribute(name);
        return value == null || value.isBlank() ? null : value.trim();
    }

    private static int integerAttribute(Element element, String name)
    {
        return integer(requiredAttribute(element, name), name);
    }

    private static long longAttribute(Element element, String name)
    {
        try
        {
            return Long.parseLong(requiredAttribute(element, name));
        }
        catch (NumberFormatException ex)
        {
            throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                    "Invalid integer BTS attribute: " + name, ex);
        }
    }

    private static Integer optionalInteger(Element element, String name)
    {
        String value = optionalAttribute(element, name);
        return value == null ? null : integer(value, name);
    }

    private static Long optionalLong(Element element, String name)
    {
        String value = optionalAttribute(element, name);
        if (value == null) return null;
        try
        {
            return Long.parseLong(value);
        }
        catch (NumberFormatException ex)
        {
            throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                    "Invalid integer BTS attribute: " + name, ex);
        }
    }

    private static int integer(String value, String name)
    {
        try
        {
            return Integer.parseInt(value);
        }
        catch (NumberFormatException ex)
        {
            throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                    "Invalid integer BTS attribute: " + name, ex);
        }
    }

    private static BigDecimal optionalDecimal(Element element, String name)
    {
        String value = optionalAttribute(element, name);
        return value == null ? null : decimal(value, name);
    }

    private static BigDecimal decimal(String value, String name)
    {
        try
        {
            return new BigDecimal(value);
        }
        catch (NumberFormatException ex)
        {
            throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                    "Invalid decimal BTS attribute: " + name, ex);
        }
    }

    private static boolean booleanText(String value, String name)
    {
        String normalized = value == null ? "" : value.trim();
        if ("true".equalsIgnoreCase(normalized)) return true;
        if ("false".equalsIgnoreCase(normalized)) return false;
        throw new BtsProtocolException(BtsProtocolException.Reason.INVALID_VALUE,
                "Invalid boolean BTS value: " + name);
    }
}