package org.simantics.district.maps.server;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.stream.Stream;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.yaml.snakeyaml.Yaml;
import org.zeroturnaround.exec.ProcessExecutor;
import org.zeroturnaround.exec.StartedProcess;
import org.zeroturnaround.exec.stream.slf4j.Slf4jStream;
import org.zeroturnaround.process.PidProcess;
import org.zeroturnaround.process.PidUtil;
import org.zeroturnaround.process.Processes;
import org.zeroturnaround.process.SystemProcess;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class TileserverMapnik {

    private static final Logger LOGGER = LoggerFactory.getLogger(TileserverMapnik.class);
    private static final String[] ADDITIONAL_DEPENDENCIES = new String[] { "tilelive-vector@3.9.4", "tilelive-tmstyle@0.6.0" };
    
    private SystemProcess process;
    private Path serverRoot;
    private int port;
    
    private AtomicBoolean running = new AtomicBoolean(false);
    
    TileserverMapnik(Path serverRoot, int port) {
        this.serverRoot = serverRoot.normalize();
        this.port = port;
    }
    
    public void setPort(int port) {
        this.port = port;
    }

    public boolean isRunning() throws IOException, InterruptedException {
        return process == null ? false : process.isAlive() && isReady();
    }
    
    public boolean isReady() {
        return running.get();
    }
    
    public void start() throws Exception {
        // check if existing server is left hanging
        if (Files.exists(getPid())) {
            String pid = new String(Files.readAllBytes(getPid()));
            PidProcess pr = Processes.newPidProcess(Integer.parseInt(pid));
            pr.destroyForcefully();
        }
        
        // check that npm dependencies are satisfied
        if (checkAndInstall(null)) {
            checkAndInstall(ADDITIONAL_DEPENDENCIES[0]);
            checkAndInstall(ADDITIONAL_DEPENDENCIES[1]);
        }
        
        checkConfigJson();
        checkTm2Styles();
        
        if (process != null && process.isAlive())
            return;
        
        StartedProcess startedProcess = new ProcessExecutor().directory(serverRoot.resolve("tileserver-mapnik").toFile()).destroyOnExit().environment(getEnv())
                .command(NodeJS.executable().toString(), getTessera().toString(), "-c", getConfigJson().toString())
                .redirectOutput(Slf4jStream.ofCaller().asDebug()).start();
        
        Process nativeProcess = startedProcess.getProcess();
        process = Processes.newStandardProcess(nativeProcess);
        int pid = PidUtil.getPid(nativeProcess);
        Files.write(getPid(), (pid + "").getBytes(), StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
        running.set(true);
    }

    private Map<String, String> getEnv() {
        Map<String, String> env = new HashMap<>();
        env.put("MAPNIK_FONT_PATH", getFonts().toString());
        env.put("ICU_DATA", getICU().toString());
        return env;
    }

    public void stop() throws IOException, InterruptedException {
        if (process != null && process.isAlive()) {
            // gracefully not supported on windows
            process.destroyForcefully();
            if (!process.waitFor(2000, TimeUnit.MILLISECONDS)) {
                process.destroyForcefully();
                if (process.isAlive())
                    LOGGER.error("Could not shutdown TileserverMapnik!");
            }
            process = null;
            Files.delete(getPid());
            running.set(false);
        }
    }

    private Path getPid() {
        return serverRoot.resolve("pid");
    }

    public void restart() throws Exception {
        stop();
        start();
    }
    
    private boolean checkIfInstalled(String module) throws Exception {
        String tileserverMapnik = tileserverMapnikRoot().toString();
        int retVal;
        try (ByteArrayOutputStream output = new ByteArrayOutputStream()) {
            if (module == null) {
                retVal = NodeJS.npm(output, "--prefix", tileserverMapnik, "list");
            } else {
                retVal = NodeJS.npm(output, "--prefix", tileserverMapnik, "list", module);
            }
            String outputString = new String(output.toByteArray(), StandardCharsets.UTF_8);
        }
        return retVal == 0;
    }
    
    private boolean install(String module) throws Exception {
        String tileserverMapnik = tileserverMapnikRoot().toString();
        int retVal;
        if (module == null)
            retVal = NodeJS.npm(null, "--prefix", tileserverMapnik, "install", "--save");
        else 
            retVal = NodeJS.npm(null, "--prefix", tileserverMapnik, "install", module, "--save");
        if (retVal != 0)
            LOGGER.warn("Could not install module " + module == null ? "package.json" : module + "! " + retVal);
        return retVal == 0;
    }
    
    private boolean checkAndInstall(String module) throws Exception {
        boolean installed = checkIfInstalled(module); 
        if (!installed)
            install(module);
        return !installed;
    }

    
    private Path tileserverMapnikRoot() {
        return serverRoot.resolve("tileserver-mapnik").toAbsolutePath();
    }
    
    private Path getFonts() {
        return serverRoot.resolve("fonts").toAbsolutePath();
    }
    
    private Path getICU() {
        return serverRoot.resolve("tileserver-mapnik/node_modules/tilelive-vector/node_modules/mapnik/lib/binding/node-v46-win32-x64/share/icu").toAbsolutePath();
    }
    
    private Path getTessera() {
        return serverRoot.resolve("tileserver-mapnik/bin/tessera.js").toAbsolutePath();
    }
    
    private Path getConfigJson() {
        return serverRoot.resolve("config.json").toAbsolutePath();
    }
    
    public List<String> availableMBTiles() throws IOException {
        Path data = serverRoot.resolve("data").toAbsolutePath();
        List<String> result = new ArrayList<>();
        try (Stream<Path> paths = Files.walk(data)) {
            paths.forEach(p -> {
                if (!p.equals(data)) {
                    String tiles = p.getFileName().toString();
                    result.add(tiles);
                }
            });
        }
        return result;
    }
    
    private void checkConfigJson() throws JsonParseException, JsonMappingException, IOException {
        Path configJson = getConfigJson();
        Map<String, Object> config = new HashMap<>();
        Path tm2 = serverRoot.resolve("tm2").toAbsolutePath();
        try (DirectoryStream<Path> stream = Files.newDirectoryStream(tm2)) {
            stream.forEach(p -> {
                Path projectYaml = p.resolve("project.yml");
                if (Files.exists(projectYaml)) {
                    // Good
                    
                    Map<String, String> source = new HashMap<>();
                    
                    Path tm2style = serverRoot.relativize(projectYaml.getParent());
                    
                    String prefix = "tmstyle://../";
                    String tmStyle = prefix + tm2style.toString(); 
                    source.put("source", tmStyle);
                    config.put("/" + projectYaml.getParent().getFileName().toString(), source);
                }
            });
        }
        ObjectMapper mapper = new ObjectMapper();
        mapper.writerWithDefaultPrettyPrinter().writeValue(Files.newOutputStream(configJson, StandardOpenOption.TRUNCATE_EXISTING), config);
    }
    
    public void checkTm2Styles() {
        Path tm2 = serverRoot.resolve("tm2").toAbsolutePath();
        try (DirectoryStream<Path> stream = Files.newDirectoryStream(tm2)) {
            stream.forEach(p -> {
                Path projectYaml = p.resolve("project.yml");
                Yaml yaml = new Yaml();
                Map<String, String> data = null;
                try (InputStream input = Files.newInputStream(projectYaml, StandardOpenOption.READ)) {
                    data = yaml.loadAs(input, Map.class);
                    
                    Path tiles = serverRoot.relativize(serverRoot.resolve("data").resolve("helsinki_finland.mbtiles"));//.toAbsolutePath().toString().replace("\\", "/");
                    
                    
                    String tmStyle = "mbtiles://../" + tiles.toString();
                    data.put("source", tmStyle);
                    
                } catch (IOException e) {
                    LOGGER.error("Could not read yaml", e);
                }
                try {
                    Files.write(projectYaml, yaml.dump(data).getBytes(), StandardOpenOption.TRUNCATE_EXISTING);
                } catch (IOException e) {
                    LOGGER.error("Could not write yaml", e);
                }
            });
        } catch (IOException e) {
            LOGGER.error("Could not browse tm2 styles", e);
        }
    }

    public List<String> listStyles() throws IOException {
        List<String> results = new ArrayList<>();
        Path tm2 = serverRoot.resolve("tm2").toAbsolutePath();
        try (DirectoryStream<Path> stream = Files.newDirectoryStream(tm2)) {
            stream.forEach(p -> {
                results.add(p.getFileName().toString());
            });
        }
        return results;
    }

}