/* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved. */

/******************************************************************************
 *
 * You may not use the identified files except in compliance with the Apache
 * License, Version 2.0 (the "License.")
 *
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0.
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * NAME
 *   webapppromises.js
 *
 * DESCRIPTION
 *   Shows a web based query using connections from connection pool. This is
 *   similar to webapp.js but uses promises.
 *
 *   This displays a table of employees in the specified department.
 *
 *   The script creates an HTTP server listening on port 7000 and
 *   accepts a URL parameter for the department ID, for example:
 *   http://localhost:7000/90
 *
 *   In some networks forced pool termination may hang unless you have
 *   'disable_oob=on' in sqlnet.ora, see
 *   https://oracle.github.io/node-oracledb/doc/api.html#tnsadmin
 *
 *   Uses Oracle's sample HR schema.  Scripts to create the HR schema
 *   can be found at: https://github.com/oracle/db-sample-schemas
 *
 *   This example requires node-oracledb 3 or later.
 *
 *****************************************************************************/

var http = require('http');
var oracledb = require('oracledb');
var dbConfig = require('./dbconfig.js');
var httpPort = 7000;

// Main entry point.  Creates a connection pool, on callback creates an
// HTTP server that executes a query based on the URL parameter given.
// The pool values shown are the default values.
function init() {
  oracledb.createPool({
    user: dbConfig.user,
    password: dbConfig.password,
    connectString: dbConfig.connectString
    // edition: 'ORA$BASE', // used for Edition Based Redefintion
    // events: false, // whether to handle Oracle Database FAN and RLB events or support CQN
    // externalAuth: false, // whether connections should be established using External Authentication
    // homogeneous: true, // all connections in the pool have the same credentials
    // poolAlias: 'default', // set an alias to allow access to the pool via a name.
    // poolIncrement: 1, // only grow the pool by one connection at a time
    // poolMax: 4, // maximum size of the pool. Increase UV_THREADPOOL_SIZE if you increase poolMax
    // poolMin: 0, // start with no connections; let the pool shrink completely
    // poolPingInterval: 60, // check aliveness of connection if idle in the pool for 60 seconds
    // poolTimeout: 60, // terminate connections that are idle in the pool for 60 seconds
    // queueTimeout: 60000, // terminate getConnection() calls in the queue longer than 60000 milliseconds
    // sessionCallback: myFunction, // function invoked for brand new connections or by a connection tag mismatch
    // stmtCacheSize: 30 // number of statements that are cached in the statement cache of each connection
  })
    .then(function(pool) {
      // Create HTTP server and listen on port - httpPort
      http
        .createServer(function(request, response) {
          handleRequest(request, response, pool);
        })
        .listen(httpPort);

      console.log("Server running at http://localhost:" + httpPort);
    })
    .catch(function(err) {
      console.error("createPool() error: " + err.message);
    });
}

function handleRequest(request, response, pool) {
  var urlparts = request.url.split("/");
  var deptid = urlparts[1];

  htmlHeader(
    response,
    "Oracle Database Driver for Node.js",
    "Example using node-oracledb driver"
  );

  if (deptid == 'favicon.ico') {
    htmlFooter(response);
    return;
  }

  if (deptid != parseInt(deptid)) {
    handleError(
      response,
      'URL path "' + deptid + '" is not an integer.  Try http://localhost:' + httpPort + '/30',
      null
    );

    return;
  }

  // Checkout a connection from the pool
  pool.getConnection()
    .then(function(connection) {
      // console.log("Connections open: " + pool.connectionsOpen);
      // console.log("Connections in use: " + pool.connectionsInUse);

      connection.execute(
        `SELECT employee_id, first_name, last_name
         FROM employees
         WHERE department_id = :id`,
        [deptid] // bind variable value
      )
        .then(function(result) {
          displayResults(response, result, deptid);

          /* Release the connection back to the connection pool */
          connection.close()
            .then(function() {
              htmlFooter(response);
            })
            .catch(function(err) {
              handleError(response, "normal release() error", err);
            });
        })
        .catch(function(err) {
          connection.close()
            .catch(function(err) {
              // Just logging because handleError call below will have already
              // ended the response.
              console.error("execute() error release() error", err);
            });
          handleError(response, "execute() error", err);
        });
    })
    .catch(function(err) {
      handleError(response, "getConnection() error", err);
    });
}

// Report an error
function handleError(response, text, err) {
  if (err) {
    text += ": " + err.message;
  }
  console.error(text);
  response.write("<p>Error: " + text + "</p>");
  htmlFooter(response);
}

// Display query results
function displayResults(response, result, deptid) {
  response.write("<h2>" + "Employees in Department " + deptid + "</h2>");
  response.write("<table>");

  // Column Title
  response.write("<tr>");
  for (var col = 0; col < result.metaData.length; col++) {
    response.write("<th>" + result.metaData[col].name + "</th>");
  }
  response.write("</tr>");

  // Rows
  for (var row = 0; row < result.rows.length; row++) {
    response.write("<tr>");
    for (col = 0; col < result.rows[row].length; col++) {
      response.write("<td>" + result.rows[row][col] + "</td>");
    }
    response.write("</tr>");
  }
  response.write("</table>");
}

// Prepare HTML header
function htmlHeader(response, title, caption) {
  response.writeHead(200, {"Content-Type": "text/html"});
  response.write("<!DOCTYPE html>");
  response.write("<html>");
  response.write("<head>");
  response.write("<style>" +
    "body {background:#FFFFFF;color:#000000;font-family:Arial,sans-serif;margin:40px;padding:10px;font-size:12px;text-align:center;}" +
    "h1 {margin:0px;margin-bottom:12px;background:#FF0000;text-align:center;color:#FFFFFF;font-size:28px;}" +
    "table {border-collapse: collapse;   margin-left:auto; margin-right:auto;}" +
    "td, th {padding:8px;border-style:solid}" +
    "</style>\n");
  response.write("<title>" + caption + "</title>");
  response.write("</head>");
  response.write("<body>");
  response.write("<h1>" + title + "</h1>");
}

// Prepare HTML footer
function htmlFooter(response) {
  response.write("</body>\n</html>");
  response.end();
}

function closePoolAndExit() {
  console.log("\nTerminating");
  try {
    // Get the pool from the pool cache and close it when no
    // connections are in use, or force it closed after 10 seconds
    oracledb.getPool().close(10, function(err) {
      if (err)
        console.error(err.message);
      else
        console.log("Pool closed");
      process.exit(0);
    });
  } catch(err) {
    console.error(err.message);
    process.exit(1);
  }
}

process
  .once('SIGTERM', closePoolAndExit)
  .once('SIGINT',  closePoolAndExit);

init();