BlogServlet.java

package de.uniregensburg.inett;

import java.io.InputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.sql.*;
import java.text.SimpleDateFormat;
import java.util.Locale;
import java.util.Scanner;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.ocpsoft.prettytime.PrettyTime;


@WebServlet("/")
public class BlogServlet extends HttpServlet
{
    private static final long serialVersionUID = 1L;

    private static final int excerptLength = 20;
    private static final String siteTitle = "InetT Aufgabe 7";
    private static final String siteName = "InetT Aufgabe 7";

    // The DB-Connection variable (gets configured in init())
    private static Connection databaseConnection;

    // HTTP Parameter names and values
    private static final String postIDParam = "pst_id";
    private static final String postTitleParam = "pst_title";
    private static final String postContentParam = "pst_text";
    private static final String postTagParam = "pst_tags";
    private static final String postCreationDateParam = "pst_creationdate";
    private static final String postCommentAmountParam = "pst_cmtcount";
    private static final String commentIDParam = "cmt_id";
    private static final String commentAuthorParam = "cmt_author";
    private static final String commentTextParam = "cmt_text";
    private static final String commentCreationDateParam = "cmt_creationdate";
    private static final String actionParam = "action";
    private static final String actionCreateView = "createview";
    private static final String actionEditView = "editview";
    private static final String actionCreateEdit = "createedit";
    private static final String actionDelete = "delete";
    private static final String actionCreateComment = "createcmt";
    private static final String actionDeleteComment = "deletecmt";

    // HTML Replacement Tags
    private static final String tagTagList = "##TAGLIST##";
    private static final String tagPostID = "##POSTID##";
    private static final String tagCSS = "##CSS##";
    private static final String tagTitle = "##TITLE##";
    private static final String tagSiteName = "##SITENAME##";
    private static final String tagDynamicContent = "##DYNAMIC_CONTENT##";
    private static final String tagPostLink = "##POSTLINK##";
    private static final String tagEditButtonIMG = "##EDITBUTTONIMG##";
    private static final String tagReadOnIMG = "##READONIMG##";
    private static final String tagPostText = "##POSTTEXT##";
    private static final String tagCommentAmount = "##COMMENTAMOUNT##";
    private static final String tagPostAge = "##POSTAGE##";
    private static final String tagPostTitle = "##POSTTITLE##";
    private static final String tagPostLinkComment = "##POSTLINKCOMMENT##";
    private static final String tagPostEditLink = "##POSTEDITLINK##";
    private static final String tagPostDeleteLink = "##POSTDELETELINK##";
    private static final String tagPostList = "##POSTLIST##";
    private static final String tagPostExcerpt = "##POSTEXCERPT##";
    private static final String tagCommentLink = "##COMMENTLINK##";
    private static final String tagCreateEditLink = "##CREATEEDITLINK##";
    private static final String tagCommentList = "##COMMENTLIST##";
    private static final String tagCommentText = "##COMMENTTEXT##";
    private static final String tagCommentID = "##COMMENTID##";
    private static final String tagCommentAuthor = "##COMMENTAUTHOR##";
    private static final String tagCommentAge = "##COMMENTAGE##";
    private static final String tagCommentDeleteLink = "##COMMENTDELETELINK##";
    private static final String tagCommentCreateAction = "##COMMENTCREATEACTION##";


    private static final String site_static_template_path = "/WEB-INF/html_templates/site_static.txt";
    private static final String post_container_template_path = "/WEB-INF/html_templates/post_container.txt";
    private static final String post_view_template_path = "/WEB-INF/html_templates/post_view.txt";
    private static final String single_post_template_path = "/WEB-INF/html_templates/single_post.txt";
    private static final String create_edit_view_template_path = "/WEB-INF/html_templates/create_edit_view.txt";
    private static final String site_404_template_path = "/WEB-INF/html_templates/site_404.txt";
    private static final String single_comment_template_path = "/WEB-INF/html_templates/single_comment.txt";

    private String site_static_template;
    private String post_container_template;
    private String post_view_template;
    private String single_post_template;
    private String create_edit_view_template;
    private String site_404_template;
    private String single_comment_template;

    public BlogServlet()
    {
        super();
    }

    public void init(ServletConfig config) throws ServletException
    {
        super.init(config);

        // Database connection
        String databaseLocation = "localhost";
        String databasePort = "3306";
        String databaseName = "blog";
        String databaseUser = "root";
        String databasePassword = "dbpass";

        try
        {
            String connectionString = "jdbc:mysql://" + databaseLocation + ":" + databasePort + "/" + databaseName + "?user=" + databaseUser + "&password=" + databasePassword;
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            databaseConnection = DriverManager.getConnection(connectionString);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        try
        {
            // Loading the HTML templates from file
            InputStream input;

            input = getServletContext().getResourceAsStream(site_static_template_path);
            site_static_template = readAll(input);
            input.close();

            input = getServletContext().getResourceAsStream(site_404_template_path);
            site_404_template = readAll(input);
            input.close();

            input = getServletContext().getResourceAsStream(post_container_template_path);
            post_container_template = readAll(input);
            input.close();

            input = getServletContext().getResourceAsStream(post_view_template_path);
            post_view_template = readAll(input);
            input.close();

            input = getServletContext().getResourceAsStream(single_post_template_path);
            single_post_template = readAll(input);
            input.close();

            input = getServletContext().getResourceAsStream(single_comment_template_path);
            single_comment_template = readAll(input);
            input.close();

            input = getServletContext().getResourceAsStream(create_edit_view_template_path);
            create_edit_view_template = readAll(input);
            input.close();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    public void destroy()
    {
        super.destroy();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        handleRequest(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        handleRequest(request, response);
    }

    void handleRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        String responseString = "";
        String self = request.getRequestURL().toString();
        PrettyTime timeFormatter = new PrettyTime(new Locale("de"));

        // Getting the HTTP Parameters
        String postID = request.getParameter(postIDParam);
        String commentID = request.getParameter(commentIDParam);
        String action = request.getParameter(actionParam);
        String postTitle = request.getParameter(postTitleParam);
        String postContent = request.getParameter(postContentParam);

        // Getting the basic site template into our response
        String site_static = site_static_template;
        site_static = site_static.replace(tagTitle, siteTitle);
        site_static = site_static.replace(tagSiteName, siteName);
        responseString += site_static;

        if (postTitle == null && postContent == null && action == null)
        {
            if (postID == null)
            {
                // String to write the post list into
                String postList = "";

                // Getting the list of all posts from the database
                ResultSet rs = executeStoredProcedure("getAllPosts");

                responseString = responseString.replace(tagDynamicContent, indentEverythingBy(post_container_template, 12));

                try
                {
                    while (rs.next())
                    {
                        // Replacing the tags with its values
                        String single_post_temp = single_post_template;
                        single_post_temp = single_post_temp.replace(tagPostID, String.valueOf(rs.getInt(postIDParam)));
                        single_post_temp = single_post_temp.replace(tagPostEditLink, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)) + "&" + actionParam + "=" + actionEditView);
                        single_post_temp = single_post_temp.replace(tagPostDeleteLink, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)) + "&" + actionParam + "=" + actionDelete);
                        single_post_temp = single_post_temp.replace(tagPostLink, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)));
                        single_post_temp = single_post_temp.replace(tagPostAge, timeFormatter.format((new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).parse(rs.getString(postCreationDateParam))));
                        single_post_temp = single_post_temp.replace(tagCommentAmount, rs.getInt(postCommentAmountParam) == 1 ? (String.valueOf(rs.getInt(postCommentAmountParam)) + " Kommentar") : (String.valueOf(rs.getInt(postCommentAmountParam)) + " Kommentare"));
                        single_post_temp = single_post_temp.replace(tagPostLinkComment, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)) + "#respond");
                        single_post_temp = single_post_temp.replace(tagPostTitle, rs.getString(postTitleParam));
                        single_post_temp = single_post_temp.replace(tagTagList, rs.getString(postTagParam));
                        single_post_temp = single_post_temp.replace(tagPostExcerpt, rs.getString(postContentParam).substring(0, Math.min(rs.getString(postContentParam).length(), excerptLength)));
                        postList += single_post_temp + "\n";
                    }
                }
                catch (Exception e)
                {
                    e.printStackTrace();
                }

                postList = postList.substring(0, postList.length() - 1);
                responseString = responseString.replace(tagPostList,  indentEverythingBy(postList, 24));
            }
            else
            {
                ResultSet rs = executeStoredProcedure("getPost", postID);

                try
                {
                    if (rs.next())
                    {
                        String post_view_temp = post_view_template;
                        post_view_temp = post_view_temp.replace(tagPostID, String.valueOf(rs.getInt(postIDParam)));
                        post_view_temp = post_view_temp.replace(tagPostEditLink, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)) + "&" + actionParam + "=" + actionEditView);
                        post_view_temp = post_view_temp.replace(tagPostDeleteLink, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)) + "&" + actionParam + "=" + actionDelete);
                        post_view_temp = post_view_temp.replace(tagPostLink, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)));
                        post_view_temp = post_view_temp.replace(tagPostAge, timeFormatter.format((new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).parse(rs.getString(postCreationDateParam))));
                        post_view_temp = post_view_temp.replace(tagCommentAmount, rs.getInt(postCommentAmountParam) == 1 ? (String.valueOf(rs.getInt(postCommentAmountParam)) + " Kommentar") : (String.valueOf(rs.getInt(postCommentAmountParam)) + " Kommentare"));
                        post_view_temp = post_view_temp.replace(tagPostLinkComment, self + "?" + postIDParam + "=" + String.valueOf(rs.getInt(postIDParam)) + "#respond");
                        post_view_temp = post_view_temp.replace(tagPostTitle, rs.getString(postTitleParam));
                        post_view_temp = post_view_temp.replace(tagTagList, rs.getString(postTagParam));
                        post_view_temp = post_view_temp.replace(tagPostText, rs.getString(postContentParam));
                        post_view_temp = post_view_temp.replace(tagCommentLink, self);
                        post_view_temp = post_view_temp.replace(tagCommentCreateAction, actionCreateComment);

                        rs = executeStoredProcedure("getPostComments", postID);
                        String commentList = "";

                        while (rs.next())
                        {
                            String single_comment_temp = single_comment_template;
                            single_comment_temp = single_comment_temp.replace(tagCommentID, String.valueOf(rs.getInt(commentIDParam)));
                            single_comment_temp = single_comment_temp.replace(tagCommentAuthor, rs.getString(commentAuthorParam) == "" ? "Anonym" : rs.getString(commentAuthorParam));
                            single_comment_temp = single_comment_temp.replace(tagCommentAge, timeFormatter.format((new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).parse(rs.getString(commentCreationDateParam))));
                            single_comment_temp = single_comment_temp.replace(tagCommentDeleteLink, self + "?" + commentIDParam + "=" + String.valueOf(rs.getInt(commentIDParam)) + "&" + actionParam + "=" + actionDeleteComment);
                            single_comment_temp = single_comment_temp.replace(tagCommentText, rs.getString(commentTextParam));
                            commentList += single_comment_temp + "\n";
                        }

                        commentList = commentList.substring(0, commentList.length() - 1);
                        post_view_temp = post_view_temp.replace(tagCommentList, indentEverythingBy(commentList, 20));
                        responseString = responseString.replace(tagDynamicContent, indentEverythingBy(post_view_temp, 12));


                        // ID valid
                        // Post-View

                    }
                    else
                    {
                        // 404
                        responseString = responseString.replace(tagDynamicContent, indentEverythingBy(site_404_template, 12));
                    }
                }
                catch (Exception e)
                {
                    e.printStackTrace();
                }
            }
        }
        else if (action == actionCreateView)
        {
            // Create / Edit Page in Create-Mode (Title and Content empty, postID = 0)
        }
        else if (action == actionEditView)
        {
            // Create / Edit Page in Edit-Mode (Title and Content prefilled, postID accordingly)
        }
        else if (action == actionCreateEdit)
        {
            if (postTitle != null && postContent != null && postTitle != "" && postContent != "")
            {
                if(postID == "0")
                {
                    // Create new post
                }
                else
                {
                    // Check for valid ID / 404
                    // Edit existing post
                }
                // Post-View
            }
            else
            {
                // Title or content unfilled Page
            }
        }
        else if (action == actionDelete)
        {
            // Check for valid ID / 404
            // Delete Post from database
            // Overview Page
        }


        PrintWriter writer = response.getWriter();
        writer.write(responseString);
        writer.close();
    }

    public ResultSet executeStoredProcedure(String name, String parameters)
    {
        try
        {
            CallableStatement proc = databaseConnection.prepareCall("{call " + name + "(" + parameters + ")}");
            return proc.executeQuery();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        return null;
    }

    public ResultSet executeStoredProcedure(String name)
    {
        return executeStoredProcedure(name, "");
    }

    public String indentEverythingBy(String text, int indent)
    {
        text = text.replace("\n", "\n" + repeatChar(' ', indent));

        return text;
    }

    public String repeatChar(char c, int length)
    {
        String temp = "";

        for (int i = 0; i < length; i++)
        {
            temp += c;
        }

        return temp;
    }

    public String readAll (InputStream input)
    {
        Scanner s = new Scanner(input);
        s.useDelimiter("\\A");
        String temp = s.hasNext() ? s.next() : "";
        s.close();
        return temp;
    }
}