package org.simantics.scl.rest;

import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.StreamingOutput;

import org.glassfish.jersey.media.multipart.FormDataContentDisposition;
import org.glassfish.jersey.media.multipart.FormDataParam;

@Path("SCLAPI")
@Produces(MediaType.APPLICATION_JSON)
public class SCLRESTAPI {

    private SCLAPI sclAPI;

    public SCLRESTAPI() {
        sclAPI = SCLAPI.getInstance();
    }
    
    private static Map<String, Object> buildJSONResponse(Object... keyValues) {
        if ((keyValues.length % 2) != 0)
            throw new IllegalArgumentException("Invalid amount of arguments! " + Arrays.toString(keyValues));
        Map<String, Object> results = new HashMap<>(keyValues.length / 2);
        for (int i = 0; i < keyValues.length; i += 2) {
            Object key = keyValues[i];
            Object value = keyValues[i + 1];
            if (!(key instanceof String))
                throw new IllegalArgumentException("Key with index " + i + " is not String");
            results.put((String) key, value);
        }
        return results;
    }
    
    @Path("/sessions")
    @POST
    public Response sessions() {
        String sessionId = UUID.randomUUID().toString(); 
        sclAPI.getOrCreateCommandSession(sessionId);
        return Response.ok(buildJSONResponse("sessionId", sessionId)).build();
    }

    @Path("/sessions/{sessionId}/modules/{moduleName:.*}")
    @PUT
    public Response upload(@PathParam("sessionId") String sessionId, @PathParam("moduleName") String moduleName, @FormDataParam("file") InputStream inputStream, @FormDataParam("file") FormDataContentDisposition fileDetail) throws IOException {
        String moduleText = getModuleText(inputStream);
        String response = sclAPI.putModule(sessionId, moduleName, moduleText);
        if (response == null)
            return Response.ok().build();
        else
            return Response.status(422).entity(buildJSONResponse("response", response)).build();
    }
    
    private static String getModuleText(InputStream inputStream) throws IOException {
        ByteArrayOutputStream result = new ByteArrayOutputStream();
        byte[] buffer = new byte[4096];
        int length;
        while ((length = inputStream.read(buffer)) != -1)
            result.write(buffer, 0, length);
        return result.toString(StandardCharsets.UTF_8.name());
    }

    @Path("/sessions/{sessionId}/execute")
    @POST
    @Produces(MediaType.TEXT_PLAIN)
    public Response execute(@PathParam("sessionId") String sessionId, @FormDataParam("command") String command) {
        final Reader reader = new InputStreamReader(new ByteArrayInputStream(command.getBytes(StandardCharsets.UTF_8)));
        return Response.ok((StreamingOutput) output -> {
            try (Writer writer = new BufferedWriter(new OutputStreamWriter(output))) {
                sclAPI.execute(sessionId, reader, writer);
                writer.flush();
            }
        }).build();
    }

    @Path("/sessions/{sessionId}/variables/{variableName}")
    @GET
    public Response variableValue(@PathParam("sessionId") String sessionId, @PathParam("variableName") String variableName) {
        Object value = sclAPI.variableValue(sessionId, variableName);
        return Response.ok(buildJSONResponse("sessionId", sessionId, "variableName", variableName, "variableValue", value)).build();
    }

    @Path("/sessions/{sessionId}/close")
    @POST
    public Response sessions(@PathParam("sessionId") String sessionId) {
        sclAPI.deleteCommandSession(sessionId);
        return Response.ok().build();
    }

}