package main;

import io.DataWriter;
import io.OAuthRequester;
import io.StreamImpl;
import java.io.IOException;
import java.util.Arrays;
import java.util.NoSuchElementException;
import java.util.Scanner;
import mining.Stream;
import mining.TwitterApi;
import org.json.JSONObject;
import provider.ExceptionListener;
import provider.ResultListener;
import utils.Configuration;

/**
 * Provides an interactive shell where requests can be made and displayed.
 */
public class TweetShell implements TwitterApi.PinSupplier {

    private final Scanner scanner = new Scanner(System.in);

    private TwitterApi api_cached;
    private Stream stream_cached;

    private TwitterApi getApi() throws IOException {
        if (api_cached == null) {
            api_cached = TwitterApi.getOAuth(this);
        }
        return api_cached;
    }

    private Stream getStream() throws IOException {
        if (stream_cached == null) {
            OAuthRequester requester = (OAuthRequester) getApi().getRequester();
            StreamHandler handler = new StreamHandler();
            stream_cached = new StreamImpl(requester);
            StreamImpl streamObserver = (StreamImpl) stream_cached;
            streamObserver.setExceptionListener(handler);
            streamObserver.setResultListener(new StreamHandler());
        }
        return stream_cached;
    }

    private class StreamHandler implements ResultListener, ExceptionListener {

        @Override
        public void exceptionGenerated(Exception ex) {
            System.err.println("Stream closed due to " + ex);
        }

        @Override
        public void tweetGenerated(JSONObject obj) {
            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
        }

        @Override
        public void profileGenerated(JSONObject obj) {
            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
        }
    }

    @Override
    public String requestPin(String url) throws IOException {
        System.err.println(url);
        System.err.println("Please open the above URL and enter PIN:");
        return scanner.nextLine();
    }

    private void printPrompt() {
        if (stream_cached == null) {
            System.out.print("$ ");
        } else {
            System.out.print("€ ");
        }
    }

    /**
     * Processes commands from stdin until the exit command is received or EOF.
     */
    public void process_forever() {
        System.err.println("Entering interactive shell, type 'help' for help "
                + "or 'exit' to leave.");
        // print prompt for reading first command
        printPrompt();
        while (scanner.hasNextLine()) {
            String line = scanner.nextLine().trim();
            String[] args = line.split("\\s+", 2);
            if (!args[0].isEmpty()) {
                // non-empty command, let's see whether it makes sense?
                if (!execute(args)) {
                    // requested to terminate
                    break;
                }
            }
            // print prompt for reading next line
            printPrompt();
        }
    }

    /**
     * Executes a command with optional parameters.
     *
     * @param args An array with the first argument containing the command with
     * optional parameters in following arguments.
     * @return true if more commands are allowed to be executed, false
     * otherwise.
     */
    public boolean execute(String[] args) {
        try {
            Command command = Command.fromString(args[0]);
            String[] params = Arrays.copyOfRange(args, 1, args.length);
            execute(command, params);
        } catch (IllegalArgumentException ex) {
            System.err.println(ex.getMessage());
        } catch (IOException ex) {
            System.err.println("Command " + args[0] + " failed with " + ex);
            ex.printStackTrace();
        } catch (NoSuchElementException ex) {
            // thrown by the "exit" command to signal exit
            return false;
        }
        // another satisfied customer, next!
        return true;
    }

    enum Command {

        add("Adds a keyword to search", 1),
        del("Deletes a keyword from search", 1),
        commit("Activate the stream or apply the stream keyword changes"),
        close("Close the stream"),
        test(""),
        exit("Returns to shell"),
        help("Get help"),
        target("Set output target: {file, shell}.");

        private final String description;
        private final int paramCount;

        Command(String description) {
            this.description = description;
            this.paramCount = 0;
        }

        Command(String description, int paramCount) {
            this.description = description;
            this.paramCount = paramCount;
        }

        public String getDescription() {
            return description;
        }

        public int getParamCount() {
            return paramCount;
        }

        public static Command fromString(String command) {
            for (Command cmd : values()) {
                if (cmd.name().equals(command)) {
                    return cmd;
                }
            }
            throw new IllegalArgumentException("Unrecognized command. Hint: help");
        }
    };

    private final String[] HELP = new String[]{
        "Interactive TweetShell",
        "",
        "Available commands:"
    };

    private void execute(Command command, String[] params) throws IOException {
        if (params.length < command.getParamCount()) {
            throw new IllegalArgumentException("Expected "
                    + command.getParamCount() + " parameters, got only "
                    + params.length);
        }
        switch (command) {
            case add:
                getStream().watchKeyword(params[0]);
                break;
            case del:
                getStream().unwatchKeyword(params[0]);
                break;
            case commit:
                getStream().commit();
                break;
            case close:
                getStream().close();
                break;
            case test:
                getStream().poll();
                break;
            case help:
                for (String line : HELP) {
                    System.out.println(line);
                }
                for (Command cmd : Command.values()) {
                    System.out.printf("  %-10s", cmd.name());
                    if (!cmd.getDescription().isEmpty()) {
                        System.out.print(" " + cmd.getDescription());
                    }
                    if (cmd.getParamCount() == 1) {
                        System.out.print(" (1 arg)");
                    } else if (cmd.getParamCount() > 1) {
                        System.out.printf(" (%d args)", cmd.getParamCount());
                    }
                    System.out.println();
                }
                break;
            case exit:
                throw new NoSuchElementException();
            case target:
                StreamImpl stream = (StreamImpl) getStream();

                ResultListener oldListener = stream.getResultListener();
                if (oldListener instanceof DataWriter) {
                    ((DataWriter) oldListener).close();
                }

                switch (params[0]) {
                    case "file":
                        if (!(oldListener instanceof DataWriter)) {
                            Configuration config = Configuration.getConfig();

                            String profilesFilename = config.getProperty(DataWriter.CFG_PROFILE_FILENAME);
                            String tweetsFilename = config.getProperty(DataWriter.CFG_TWEETS_FILENAME);

                            stream.setResultListener(new DataWriter(profilesFilename, tweetsFilename));

                            // save the changes to the config.
                            config.save();
                        }
                        break;
                    case "shell":
                        if (!(oldListener instanceof StreamHandler)) {
                            stream.setResultListener(new StreamHandler());
                        }
                        break;
                }
                break;
            default:
                throw new AssertionError(command.name());
        }

    }
;
}