package com.mes.util;

import com.alibaba.fastjson2.JSONObject;
import com.github.xingshuangs.iot.protocol.melsec.enums.EMcFrameType;
import com.github.xingshuangs.iot.protocol.melsec.enums.EMcSeries;
import com.github.xingshuangs.iot.protocol.melsec.service.McPLC;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.URI;
import java.net.URLDecoder;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executors;

public class PlcProxyServer {

    private static final Logger log = LoggerFactory.getLogger(PlcProxyServer.class);
    private static final int DEFAULT_PORT = 18080;
    private static final int DEFAULT_CONNECT_TIMEOUT_MS = 2000;
    private static final int DEFAULT_RECEIVE_TIMEOUT_MS = 3000;

    private static final Map<String, Object> PLC_LOCKS = new HashMap<>();
    private static final Map<String, McPLC> PLC_CACHE = new HashMap<>();

    public static void main(String[] args) throws Exception {
        Properties props = ConfigUtils.loadPropertiesUnchecked();
        PlcTarget.setProperties(props);
        int port = parseInt(props.getProperty("plc.proxy.server.port"), DEFAULT_PORT);
        HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);
        server.createContext("/health", new HealthHandler());
        server.createContext("/readBoolean", new ReadBooleanHandler());
        server.createContext("/readBooleans", new ReadBooleansHandler());
        server.createContext("/readInt16", new ReadInt16Handler());
        server.createContext("/writeBoolean", new WriteBooleanHandler());
        server.setExecutor(Executors.newCachedThreadPool());
        server.start();
        log.info("PLC proxy server started, port={}", port);
        System.out.println("PLC proxy server started, port=" + port);
    }

    private static class HealthHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) {
            JSONObject json = ok();
            json.put("status", "UP");
            writeJson(exchange, 200, json);
        }
    }

    private static class ReadBooleanHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) {
            handlePlc(exchange, new PlcAction() {
                @Override
                public Object execute(McPLC plc, Map<String, String> params) {
                    return plc.readBoolean(required(params, "address"));
                }
            });
        }
    }

    private static class ReadBooleansHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) {
            handlePlc(exchange, new PlcAction() {
                @Override
                public Object execute(McPLC plc, Map<String, String> params) {
                    int count = parseInt(params.get("count"), 1);
                    return plc.readBoolean(required(params, "address"), count);
                }
            });
        }
    }

    private static class ReadInt16Handler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) {
            handlePlc(exchange, new PlcAction() {
                @Override
                public Object execute(McPLC plc, Map<String, String> params) {
                    return plc.readInt16(required(params, "address"));
                }
            });
        }
    }

    private static class WriteBooleanHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) {
            handlePlc(exchange, new PlcAction() {
                @Override
                public Object execute(McPLC plc, Map<String, String> params) {
                    boolean value = Boolean.parseBoolean(required(params, "value"));
                    plc.writeBoolean(required(params, "address"), value);
                    return Boolean.valueOf(value);
                }
            });
        }
    }

    private static void handlePlc(HttpExchange exchange, PlcAction action) {
        Map<String, String> params = parseQuery(exchange.getRequestURI());
        try {
            PlcTarget target = PlcTarget.from(params);
            Object result;
            synchronized (getPlcLock(target.key)) {
                McPLC plc = getCachedPlc(target);
                try {
                    result = action.execute(plc, params);
                } catch (RuntimeException e) {
                    discardCachedPlc(target.key, plc);
                    throw e;
                }
            }
            JSONObject json = ok();
            json.put("value", result);
            writeJson(exchange, 200, json);
        } catch (Exception e) {
            log.warn("PLC proxy request failed, uri={}", exchange.getRequestURI(), e);
            JSONObject json = new JSONObject();
            json.put("success", false);
            json.put("message", e.getMessage());
            writeJson(exchange, 500, json);
        }
    }

    private static McPLC getCachedPlc(PlcTarget target) {
        McPLC plc = PLC_CACHE.get(target.key);
        if (plc == null) {
            plc = createPlc(target);
            PLC_CACHE.put(target.key, plc);
            log.info("PLC proxy connected, plc={}, series={}, frame={}", target.key, target.series, target.frame);
        }
        return plc;
    }

    private static McPLC createPlc(PlcTarget target) {
        EMcSeries series = parseSeries(target.series);
        EMcFrameType frameType = parseFrameType(target.frame, series.getFrameType());
        McPLC plc = new McPLC(series, frameType, target.ip, target.port);
        plc.setConnectTimeout(DEFAULT_CONNECT_TIMEOUT_MS);
        plc.setReceiveTimeout(DEFAULT_RECEIVE_TIMEOUT_MS);
        return plc;
    }

    private static void discardCachedPlc(String key, McPLC plc) {
        McPLC cached = PLC_CACHE.get(key);
        if (cached == plc) {
            PLC_CACHE.remove(key);
        }
        if (plc != null) {
            plc.close();
        }
    }

    private static Object getPlcLock(String key) {
        synchronized (PLC_LOCKS) {
            Object lock = PLC_LOCKS.get(key);
            if (lock == null) {
                lock = new Object();
                PLC_LOCKS.put(key, lock);
            }
            return lock;
        }
    }

    private static JSONObject ok() {
        JSONObject json = new JSONObject();
        json.put("success", true);
        return json;
    }

    private static void writeJson(HttpExchange exchange, int status, JSONObject json) {
        byte[] body = json.toJSONString().getBytes(java.nio.charset.StandardCharsets.UTF_8);
        try {
            exchange.getResponseHeaders().set("Content-Type", "application/json;charset=UTF-8");
            exchange.sendResponseHeaders(status, body.length);
            try (OutputStream os = exchange.getResponseBody()) {
                os.write(body);
            }
        } catch (Exception e) {
            log.warn("write proxy response failed", e);
        } finally {
            exchange.close();
        }
    }

    private static Map<String, String> parseQuery(URI uri) {
        Map<String, String> params = new HashMap<>();
        String query = uri.getRawQuery();
        if (query == null || query.isEmpty()) {
            return params;
        }
        String[] pairs = query.split("&");
        for (String pair : pairs) {
            int index = pair.indexOf('=');
            String key = index >= 0 ? pair.substring(0, index) : pair;
            String value = index >= 0 ? pair.substring(index + 1) : "";
            params.put(decode(key), decode(value));
        }
        return params;
    }

    private static String required(Map<String, String> params, String key) {
        String value = params.get(key);
        if (value == null || value.trim().isEmpty()) {
            throw new IllegalArgumentException("missing parameter: " + key);
        }
        return value;
    }

    private static String decode(String value) {
        try {
            return URLDecoder.decode(value, "UTF-8");
        } catch (Exception e) {
            return value;
        }
    }

    private static EMcSeries parseSeries(String series) {
        if ("Q_L".equalsIgnoreCase(series)) {
            return EMcSeries.Q_L;
        }
        if ("IQ_R".equalsIgnoreCase(series)) {
            return EMcSeries.IQ_R;
        }
        return EMcSeries.QnA;
    }

    private static EMcFrameType parseFrameType(String frameType, EMcFrameType defaultValue) {
        if (frameType == null || frameType.trim().isEmpty()) {
            return defaultValue;
        }
        String normalized = frameType.trim().toUpperCase(Locale.ROOT);
        if (!normalized.startsWith("FRAME_")) {
            normalized = "FRAME_" + normalized;
        }
        try {
            return EMcFrameType.valueOf(normalized);
        } catch (Exception e) {
            return defaultValue;
        }
    }

    private static int parseInt(String value, int defaultValue) {
        try {
            return Integer.parseInt(value);
        } catch (Exception e) {
            return defaultValue;
        }
    }

    private interface PlcAction {
        Object execute(McPLC plc, Map<String, String> params);
    }

    private static class PlcTarget {
        private static Properties properties = new Properties();
        private final String key;
        private final String ip;
        private final int port;
        private final String series;
        private final String frame;

        private PlcTarget(String ip, int port, String series, String frame) {
            this.ip = ip;
            this.port = port;
            this.series = firstNotEmpty(series, findConfiguredValue(ip, port, "plc.series"));
            this.frame = firstNotEmpty(frame, findConfiguredValue(ip, port, "plc.frame"));
            this.key = ip + ":" + port;
        }

        private static void setProperties(Properties props) {
            properties = props == null ? new Properties() : props;
        }

        private static PlcTarget from(Map<String, String> params) {
            String plc = required(params, "plc");
            int index = plc.lastIndexOf(':');
            if (index <= 0 || index == plc.length() - 1) {
                throw new IllegalArgumentException("invalid plc parameter: " + plc);
            }
            String ip = plc.substring(0, index);
            int port = parseInt(plc.substring(index + 1), 0);
            if (port <= 0) {
                throw new IllegalArgumentException("invalid plc port: " + plc);
            }
            return new PlcTarget(ip, port, params.get("series"), params.get("frame"));
        }

        private static String findConfiguredValue(String ip, int port, String suffix) {
            for (Object keyObj : properties.keySet()) {
                String key = String.valueOf(keyObj);
                if (!key.endsWith(".plc.ip")) {
                    continue;
                }
                String prefix = key.substring(0, key.length() - ".plc.ip".length());
                String configuredIp = properties.getProperty(prefix + ".plc.ip");
                int configuredPort = parseInt(properties.getProperty(prefix + ".plc.port"), 0);
                if (ip.equals(configuredIp) && port == configuredPort) {
                    return properties.getProperty(prefix + "." + suffix);
                }
            }
            return "";
        }

        private static String firstNotEmpty(String first, String second) {
            if (first != null && !first.trim().isEmpty()) {
                return first;
            }
            return second == null ? "" : second;
        }
    }
}