1 files changed, 83 insertions, 0 deletions
diff --git a/util/progressStats.js b/util/progressStats.js
new file mode 100644
index 0000000..f9794ed
--- /dev/null
+++ b/util/progressStats.js
@@ -0,0 +1,83 @@
+class ProgressStats {
+  constructor (trackerName, totalTasks) {
+    this.trackerName = trackerName
+    this.totalTasks = totalTasks
+    this.taskCounter = 0
+  }
+
+  logNext () {
+    this.taskCounter++
+    if (!this.beginTime) {
+      this.beginTime = new Date()
+    }
+  }
+
+  /**
+     * Begin a new task.  Print the current progress and then increment the number of tasks.
+     * @param  {string}    A short message about the current task progress
+     * @param  {[boolean]} logTimeLeft whether or not to log the time left.
+     */
+  beginTask (message, logTimeLeft) {
+    this.printStats(message, logTimeLeft)
+    this.logNext()
+  }
+
+  /**
+     * Print the current progress.
+     * @param  {string}    A short message about the current task progress
+     * @param  {[boolean]} logTimeLeft whether or not to log the time left.
+     */
+  printStats (message, logTimeLeft) {
+    message = `${message}; ${this.trackerName} progress: ${this.getPercentage()}% done`
+    if (logTimeLeft) {
+      message = `${message} - ${this.getTimeLeft()} left`
+    }
+    console.log(message)
+  }
+
+  /**
+     * calculates the percentage of finished downloads
+     * @returns {string}
+     */
+  getPercentage () {
+    var current = (this.taskCounter / this.totalTasks)
+    return Math.round(current * 1000.0) / 10.0
+  }
+
+  /**
+     * calculates the time left and outputs it in human readable format
+     * calculation is based on the average time per task so far
+     *
+     * @returns {string}
+     */
+  getTimeLeft () {
+    if (this.taskCounter === 0) return '?'
+    const averageTimePerTask = (Date.now() - this.beginTime.getTime()) / this.taskCounter
+    var tasksLeft = this.totalTasks - this.taskCounter
+    var millisecondsLeft = averageTimePerTask * tasksLeft
+    return this.formatMilliseconds(millisecondsLeft)
+  }
+
+  /**
+     * inspired from https://stackoverflow.com/questions/19700283/how-to-convert-time-milliseconds-to-hours-min-sec-format-in-javascript
+     * @param millisec
+     * @returns {string}
+     */
+  formatMilliseconds (millisec) {
+    var seconds = (millisec / 1000).toFixed(1)
+    var minutes = (millisec / (1000 * 60)).toFixed(1)
+    var hours = (millisec / (1000 * 60 * 60)).toFixed(1)
+    var days = (millisec / (1000 * 60 * 60 * 24)).toFixed(1)
+    if (seconds < 60) {
+      return seconds + ' seconds'
+    } else if (minutes < 60) {
+      return minutes + ' minutes'
+    } else if (hours < 24) {
+      return hours + ' hours'
+    } else {
+      return days + ' days'
+    }
+  }
+}
+
+module.exports = ProgressStats