Improved styling and comments

countersql/database.go

@@ -32,7 +32,6 @@ func (conn Connection) HasIPVisited(ipAddress string) (bool, error) {
 
 // GetUniqueVisits counts the number of entires in the visits table, representing one unique source IP address per row
 func (conn Connection) GetUniqueVisits() (int, error) {
-
 	rows, err := conn.DB.Query(`SELECT COUNT(*) FROM visit`)
 	if err != nil {
 		return 0, fmt.Errorf("SELECT query failed: %v", err)
@@ -72,569 +71,15 @@ func (conn Connection) AddVisitor(ipAddress string) error {
 	return nil
 }
 
-//
-
-/*
-
-// ************************************
-// Task Database Functions
-// ************************************
-
-// GetTasks returns a slice of all tasks in the database.  It requires
-// a boolean parameter.  If true, it only returns active tasks.  If false
-// it will return all tasks.  A task is active if the time now is past
-// the planned_start date.
-func (conn Connection) GetTasks(activeTasksOnly bool) ([]Task, error) {
-	var rows *sql.Rows
-	var err error
-	if activeTasksOnly {
-		rows, err = conn.DB.Query(`SELECT
-									tasks.id, tasks.name, tasks.weight, tasks.timecost, tasks.planned_start, tasks.planned_end, tasks.actual_start, tasks.actual_end, tasks.expire_action, tasks.close_code, lists.id, lists.name
-									FROM tasks
-									INNER JOIN lists
-									ON tasks.list_id = lists.id
-									WHERE tasks.close_code IS NULL AND tasks.planned_start < ?
-									ORDER BY tasks.actual_start DESC, tasks.weight DESC`, time.Now().Add(-time.Hour*6))
-
-	} else {
-		rows, err = conn.DB.Query(`SELECT
-									tasks.id, tasks.name, tasks.weight, tasks.timecost, tasks.planned_start, tasks.planned_end, tasks.actual_start, tasks.actual_end, tasks.expire_action, tasks.close_code, lists.id, lists.name
-									FROM tasks
-									INNER JOIN lists
-									ON tasks.list_id = lists.id
-									ORDER BY tasks.actual_start DESC, tasks.weight DESC`)
-	}
-	if err != nil {
-		return nil, fmt.Errorf("SELECT query failed: %v", err)
-	}
-	defer rows.Close()
-
-	if !rows.Next() {
-		return nil, nil
-	}
-
-	var tasks []Task
-	for {
-		task := Task{}
-		if err := rows.Scan(&task.ID, &task.Name, &task.Weight, &task.TimeCost, &task.PlannedStart, &task.PlannedEnd, &task.ActualStart, &task.ActualEnd, &task.ExpireAction, &task.CloseCode, &task.List.ID, &task.List.Name); err != nil {
-			return nil, fmt.Errorf("failed to scan database row: %v", err)
-		}
-		tasks = append(tasks, task)
-		if !rows.Next() {
-			break
-		}
-	}
-	return tasks, nil
-}
-
-// GetTasksByListID returns a slice of all tasks on a specific list in the database
-func (conn Connection) GetTasksByListID(listID int, activeTasksOnly bool) ([]Task, error) {
-	activeTasksQuery := ""
-	if activeTasksOnly {
-		activeTasksQuery = " AND tasks.close_code IS NULL"
-	}
-	rows, err := conn.DB.Query(`SELECT
-								tasks.id, tasks.name, tasks.weight, tasks.timecost, tasks.planned_start, tasks.planned_end, tasks.actual_start, tasks.actual_end, tasks.expire_action, tasks.close_code, lists.id, lists.name
-								FROM tasks
-								INNER JOIN lists ON tasks.list_id = list.id
-								WHERE lists.id = ? `+activeTasksQuery, listID)
-	if err != nil {
-		return nil, fmt.Errorf("SELECT query failed: %v", err)
-	}
-	defer rows.Close()
-
-	if !rows.Next() {
-		return nil, nil
-	}
-
-	var tasks []Task
-	for {
-		task := Task{}
-		if err := rows.Scan(&task.ID, &task.Name, &task.Weight, &task.TimeCost, &task.PlannedStart, &task.PlannedEnd, &task.ActualStart, &task.ActualEnd, &task.ExpireAction, &task.CloseCode, &task.List.ID, &task.List.Name); err != nil {
-			return nil, fmt.Errorf("failed to scan database row: %v", err)
-		}
-		tasks = append(tasks, task)
-		if !rows.Next() {
-			break
-		}
-	}
-	return tasks, nil
-}
-
-// GetTaskByID returns a task matching the ID provided
-func (conn Connection) GetTaskByID(taskID int) (*Task, error) {
-	rows, err := conn.DB.Query(`SELECT
-								tasks.id, tasks.name, tasks.weight, tasks.timecost, tasks.planned_start, tasks.planned_end, tasks.actual_start, tasks.actual_end, tasks.expire_action, tasks.close_code, lists.id, lists.name
-								FROM tasks
-								INNER JOIN lists ON tasks.list_id = list.id
-								WHERE tasks.id = ? `, taskID)
-	if err != nil {
-		return nil, fmt.Errorf("SELECT query failed: %v", err)
-	}
-	defer rows.Close()
-
-	if !rows.Next() {
-		return nil, fmt.Errorf("no results returned for taskID '%d'", taskID)
-	}
-
-	task := Task{}
-	if err := rows.Scan(&task.ID, &task.Name, &task.Weight, &task.TimeCost, &task.PlannedStart, &task.PlannedEnd, &task.ActualStart, &task.ActualEnd, &task.ExpireAction, &task.CloseCode, &task.List.ID, &task.List.Name); err != nil {
-		return nil, fmt.Errorf("failed to scan database row: %v", err)
-	}
-
-	return &task, nil
-}
-
-// NewTask will insert a row into the database, given a pre-instantiated task
-func (conn Connection) NewTask(task *Task) error {
-	_, err := conn.DB.Exec(`INSERT INTO tasks
-							(list_id, name, weight, timecost, planned_start, planned_end, actual_start, actual_end, expire_action, close_code)
-							VALUES (?, ?, ?, ?, ?, ?, NULL, NULL, ?, NULL)`, task.List.ID, task.Name, task.Weight, task.TimeCost, task.PlannedStart, task.PlannedEnd, task.ExpireAction)
-	if err != nil {
-		return fmt.Errorf("INSERT query failed: %v", err)
-	}
-
-	return nil
-}
-
-// DeleteTaskByID will remove a row from the database, given a list ID
-func (conn Connection) DeleteTaskByID(taskID int) error {
-	_, err := conn.DB.Exec("DELETE FROM tasks WHERE tasks.id = ?", taskID)
-
-	if err != nil {
-		return fmt.Errorf("Delete query failed: %v", err)
-	}
-
-	return nil
-}
-
-// StartTask will set the actual_start to now, given a task ID.  This marks the task as active and started
-func (conn Connection) StartTask(taskID int) error {
-	_, err := conn.DB.Exec("UPDATE tasks SET actual_start = now() WHERE tasks.id = ?", taskID)
-
-	if err != nil {
-		return fmt.Errorf("Delete query failed: %v", err)
-	}
-
-	return nil
-}
-
-// UpdateTask will update a task row in the database, given a pre-instantiated task
-func (conn Connection) UpdateTask(task *Task) error {
-
-	var err error
-	_, err = conn.DB.Exec(`UPDATE tasks SET
-							list_id = ?,
-							name = ?,
-							weight = ?,
-							timecost = ?,
-							planned_start = ?,
-							planned_end = ?,
-							actual_start = ?,
-							actual_end = ?,
-							expire_action = ?,
-							close_code = ?
-							WHERE id = ?`,
-		task.List.ID, task.Name, task.Weight, task.TimeCost, task.PlannedStart, task.PlannedEnd, task.ActualStart, task.ActualEnd, task.ExpireAction, task.CloseCode, task.ID)
-	if err != nil {
-		return fmt.Errorf("UPDATE task query failed for %d: %v", task.ID, err)
-	}
-
-	return nil
-}
-
-// StopTask will stop a task by setting the close code
-// closeCode can be: completed, cancelled or reset
-// completed is self explanatory.
-// cancelled indicates the task itself is being canelled / skipped
-// reset is not an official close code, but indicates that actual_start should be cleared (timer reset)
-func (conn Connection) StopTask(taskID int, closeCode string) error {
-	var err error
-	if closeCode == "reset" {
-		_, err = conn.DB.Exec("UPDATE tasks SET actual_start = NULL WHERE tasks.id = ?", taskID)
-	} else if closeCode == "cancelled" {
-		_, err = conn.DB.Exec("UPDATE tasks SET actual_end = now(), close_code = 'cancelled' WHERE tasks.id = ?", taskID)
-	} else if closeCode == "completed" {
-		_, err = conn.DB.Exec("UPDATE tasks SET actual_end = now(), close_code = 'completed' WHERE tasks.id = ?", taskID)
-	} else {
-		err = fmt.Errorf("invalid close code: '%s' - must be reset, cancelled or completed", closeCode)
-	}
-
-	if err != nil {
-		return fmt.Errorf("StopTask query failed: %v", err)
-	}
-
-	return nil
-}
-
-// ************************************
-// List Database Functions
-// ************************************
-
-// GetLists returns a slice of all lists in the database.
-// If joinLocations is true, it will grab the locations as well
-func (conn Connection) GetLists(getListLocations bool) ([]List, error) {
-
-	rows, err := conn.DB.Query(`SELECT
-								lists.id, lists.name
-								FROM lists`)
-	if err != nil {
-		return nil, fmt.Errorf("SELECT query failed: %v", err)
-	}
-	defer rows.Close()
-
-	if !rows.Next() {
-		return nil, nil
-	}
-
-	var lists []List
-	for {
-		list := List{}
-		if err := rows.Scan(&list.ID, &list.Name); err != nil {
-			return nil, fmt.Errorf("failed to scan database row: %v", err)
-		}
-		lists = append(lists, list)
-		if !rows.Next() {
-			break
-		}
-	}
-
-	if getListLocations {
-		wg := sync.WaitGroup{}
-		m := sync.Mutex{}
-		for i := range lists {
-			wg.Add(1)
-			go func(i int) {
-				defer wg.Done()
-				rows, err := conn.DB.Query(`SELECT
-											listlocations.location_id, locations.name
-											FROM listlocations
-											INNER JOIN locations
-											ON listlocations.location_id = locations.id
-											WHERE list_id = ?`, lists[i].ID)
-				defer rows.Close()
-				if err != nil {
-					log.Printf("SELECT listlocations query failed: %v", err)
-					return
-				}
-
-				if !rows.Next() {
-					return
-				}
-
-				var locations []Location
-				for {
-					var location Location
-					if err := rows.Scan(&location.ID, &location.Name); err != nil {
-						log.Printf("failed to scan database row: %v", err)
-						continue
-					}
-					locations = append(locations, location)
-					if !rows.Next() {
-						break
-					}
-				}
-				m.Lock()
-				lists[i].Locations = locations
-				m.Unlock()
-			}(i)
-		}
-		wg.Wait() // wait
-	}
-
-	return lists, nil
-}
-
-// GetListByID will return a single list in the database with the given ID
-func (conn Connection) GetListByID(listID int, getListLocations bool) (*List, error) {
-	rows, err := conn.DB.Query(`SELECT
-								lists.name
-								FROM lists
-								WHERE lists.id = ?
-								LIMIT 1`, listID)
-	if err != nil {
-		return nil, fmt.Errorf("SELECT query failed: %v", err)
-	}
-	defer rows.Close()
-
-	if !rows.Next() {
-		return nil, fmt.Errorf("no results returned for listID '%d'", listID)
-	}
-
-	list := List{}
-	if err := rows.Scan(&list.Name); err != nil {
-		return nil, fmt.Errorf("failed to scan database row: %v", err)
-	}
-	list.ID = listID
-
-	if getListLocations {
-		rows, err := conn.DB.Query(`SELECT
-									listlocations.location_id
-									FROM listlocations
-									WHERE list_id = ?`, list.ID)
-		defer rows.Close()
-		if err != nil {
-			return nil, fmt.Errorf("SELECT listlocations query failed: %v", err)
-		}
-
-		if !rows.Next() {
-			return nil, fmt.Errorf("no results returned for listID '%d'", listID)
-		}
-
-		var locations []Location
-		for {
-			var location Location
-			if err := rows.Scan(&location.ID); err != nil {
-				log.Printf("failed to scan database row: %v", err)
-				break
-			}
-			locations = append(locations, location)
-			if !rows.Next() {
-				break
-			}
-		}
-		list.Locations = locations
-	}
-
-	return &list, nil
-}
-
-// NewList will insert a row into the database, given a pre-instantiated list
-func (conn Connection) NewList(list *List) error {
-	result, err := conn.DB.Exec(`INSERT
-							INTO lists
-							(name)
-							VALUES (?)`, list.Name)
-	if err != nil {
-		return fmt.Errorf("INSERT list query failed: %v", err)
-	}
-
-	lastInsertID, _ := result.LastInsertId()
-
-	query := `	INSERT
-				INTO listlocations
-				(list_id, location_id)
-				VALUES `
-	// TBD: Handle list location mapping inserts here, loop through and build query, then execute it.
-	values := []interface{}{}
-	for _, listLocation := range list.Locations {
-		values = append(values, lastInsertID, listLocation.ID)
-		// the rest of this loop is magic lifted from https://play.golang.org/p/YqNJKybpwWB
-		numFields := 2
-
-		query += `(`
-		for j := 0; j < numFields; j++ {
-			query += `?,`
-		}
-		query = query[:len(query)-1] + `),`
-	}
-	query = query[:len(query)-1] // this is also part of the above mentioned magic
-	_, err = conn.DB.Exec(query, values...)
-	if err != nil {
-		return fmt.Errorf("INSERT listlocations query failed: %v", err)
-	}
-	return nil
-}
-
-// UpdateList will update a list row in the database, given a pre-instantiated list
-func (conn Connection) UpdateList(list *List) error {
-	wg := sync.WaitGroup{}
-	wg.Add(2)
-	var err error
-	go func() {
-		defer wg.Done()
-		_, err = conn.DB.Exec(`UPDATE lists
-							(name)
-							VALUES (?)`, list.Name)
-		if err != nil {
-			err = fmt.Errorf("INSERT list query failed: %v", err)
-			return
-		}
-	}()
-
-	// Handle list locations...  Have fun
-	go func() {
-		defer wg.Done()
-		var rows *sql.Rows
-		rows, err = conn.DB.Query(`SELECT
-									listlocations.location_id
-									WHERE list_id = ?`, list.ID)
-		if err != nil {
-			err = fmt.Errorf("SELECT listlocations query failed: %v", err)
-			return
-		}
-		defer rows.Close()
-
-		var locationIDsToRemove, locationIDsToAdd, dbIDs []int
-
-		if rows.Next() { // If this is false, the list has no assigned locations in the database currently
-
-			// We loop through databaseRows and determine locations that need to be removed
-			for {
-				var currDBID int
-				if err := rows.Scan(&currDBID); err != nil {
-					err = fmt.Errorf("failed to scan listlocations database row: %v", err)
-					return
-				}
-				matchFound := false
-				for _, currNewLocation := range list.Locations {
-					if currNewLocation.ID == currDBID { // If we find a match, we know this is a location that both exists in the database, and is set on the new object, so we wouldn't take action
-						matchFound = true
-						continue
-					}
-				}
-
-				if !matchFound { // If we don't find a match, we know that this row in the database should be removed because it's no longer set on the new listObject
-					locationIDsToRemove = append(locationIDsToRemove, currDBID)
-				}
-				// We collect the locationIDs while looping through the database rows so we can re-use them below
-				dbIDs = append(dbIDs, currDBID)
-
-				if !rows.Next() {
-					break
-				}
-			}
-
-			// We loop through the newly set locations and determine any that need to be added to the database
-			for _, currNewLocation := range list.Locations {
-				matchFound := false
-				for _, currDBID := range dbIDs {
-					if currNewLocation.ID == currDBID { // If we find a match, we know the location is set on the new object and already exists in the database, so we take no action
-						matchFound = true
-						continue
-					}
-				}
-
-				if !matchFound { // If we don't find a match, we know the location is set on the new object, but doesn't exist in the database, so we need to add it
-					locationIDsToAdd = append(locationIDsToAdd, currNewLocation.ID)
-				}
-			}
-		} else { // If there are no rows in the database then we know we just need to all all locations set on this new list object and put them in the database
-			for _, currNewLocation := range list.Locations {
-				locationIDsToAdd = append(locationIDsToAdd, currNewLocation.ID)
-			}
-		}
-
-		// We now have populated locationIDsToAdd and locationIDsToRemove, so we just need to build and execute the queries
-		wg.Add(2)
-		go func() {
-			defer wg.Done()
-			query := `	INSERT
-				INTO listlocations
-				(list_id, location_id)
-				VALUES `
-			// TBD: Handle list location mapping inserts here, loop through and build query, then execute it.
-			values := []interface{}{}
-			for _, locationID := range locationIDsToAdd {
-				values = append(values, list.ID, locationID)
-				// the rest of this loop is magic lifted from https://play.golang.org/p/YqNJKybpwWB
-				numFields := 2
-
-				query += `(`
-				for j := 0; j < numFields; j++ {
-					query += `?,`
-				}
-				query = query[:len(query)-1] + `),`
-			}
-			query = query[:len(query)-1] // this is also part of the above mentioned magic
-			_, err = conn.DB.Exec(query, values...)
-			if err != nil {
-				err = fmt.Errorf("INSERT listlocations query failed: %v", err)
-				return
-			}
-		}()
-
-		go func() {
-			defer wg.Done()
-			query := `	DELETE
-						FROM listlocations
-						WHERE `
-			values := []interface{}{}
-			for _, locationID := range locationIDsToRemove {
-				values = append(values, list.ID, locationID)
-
-				query += `(list_id = ? AND location_id = ?) OR`
-			}
-			query = query[:len(query)-3]
-			_, err = conn.DB.Exec(query, values...)
-			if err != nil {
-				err = fmt.Errorf("DELETE listlocations query failed: %v", err)
-				return
-			}
-		}()
-	}()
-	wg.Wait()
-	if err != nil {
-		return fmt.Errorf("a goroutine in UpdateList failed: %v", err)
-	}
-
-	return nil
-}
-
-// DeleteListByID will remove a row from the database, given a list ID
-func (conn Connection) DeleteListByID(listID int) error {
-	_, err := conn.DB.Exec("DELETE FROM lists WHERE lists.id = ?", listID)
-
-	if err != nil {
-		return fmt.Errorf("Delete query failed: %v", err)
-	}
-
-	return nil
-}
-
-// ************************************
-// Location Database Functions
-// ************************************
-
-// GetLocations returns a slice of all locations in the database
-func (conn Connection) GetLocations() ([]Location, error) {
-	rows, err := conn.DB.Query(`SELECT
-								locations.id, locations.name, locations.mac_address
-								FROM locations`)
-	if err != nil {
-		return nil, fmt.Errorf("SELECT query failed: %v", err)
-	}
-	defer rows.Close()
-
-	if !rows.Next() {
-		return nil, nil
-	}
-
-	var locations []Location
-	for {
-		location := Location{}
-		if err := rows.Scan(&location.ID, &location.Name, &location.MACAddress); err != nil {
-			return nil, fmt.Errorf("failed to scan database row: %v", err)
-		}
-		locations = append(locations, location)
-		if !rows.Next() {
-			break
-		}
-	}
-	return locations, nil
-}
-
-// DeleteLocationByID will remove a row from the database, given a list ID
-func (conn Connection) DeleteLocationByID(locationID int) error {
-	_, err := conn.DB.Exec(`DELETE
-							FROM locations
-							WHERE locations.id = ?`, locationID)
-	if err != nil {
-		return fmt.Errorf("Delete query failed: %v", err)
-	}
-
-	return nil
-}
-
-*/
-
 // Connect will open a TCP connection to the database with the given DSN configuration
 func (conf Configuration) Connect() (*Connection, error) {
 	conn := &Connection{}
 	var err error
+
 	conn.DB, err = sql.Open("mysql", conf.DSN)
 	if err != nil {
 		return nil, fmt.Errorf("failed to open db: %v", err)
 	}
+
 	return conn, nil
 }

main.go

@@ -1,3 +1,11 @@
+/*
+This application ensures the required environment variables are set
+Then it uses the included countersql package to test a connection to the database
+It then caches the number of unique visits in memory by querying the database
+Finally, it sets up a web server with the endpoint http://localhost:8080/
+For each unique source IP address which makes a GET request to this endpoint,
+the count of unique visitors is incremented by 1, both in the database and in memory cache.
+*/
 package main
 
 import (
@@ -12,8 +20,8 @@ import (
 )
 
 var (
-	database     countersql.Configuration
+	database     countersql.Configuration // Configuration information required to connect to the database, using the countersql package
-	uniqueVisits int
+	uniqueVisits int                      // In memory cache of unique visitors
 )
 
 // Application Startup
@@ -59,7 +67,6 @@ func init() {
 
 // HTTP Routing
 func main() {
-
 	// API Handlers
 	http.HandleFunc("/", countHandler)
 
@@ -68,10 +75,14 @@ func main() {
 
 }
 
+// HTTP handler function
 func countHandler(w http.ResponseWriter, r *http.Request) {
 	if r.Method == "GET" {
+		// CORS header change required
 		w.Header().Set("Access-Control-Allow-Origin", "*")
 		w.Write([]byte(strconv.Itoa(uniqueVisits)))
+
+		// Connect to database
 		dbConn, err := database.Connect()
 		if err != nil {
 			log.Printf("failed to connect to database: %v", err)
@@ -80,16 +91,17 @@ func countHandler(w http.ResponseWriter, r *http.Request) {
 		}
 		defer dbConn.DB.Close()
 
+		// We now get the source IP address of this request
 		var ipAddress string
-
+		// Check if we're behind a reverse proxy / WAF
 		if len(r.Header.Get("X-Forwarded-For")) > 0 {
 			ipAddress = r.Header.Get("X-Forwarded-For")
 		} else {
 			ipAddress = r.RemoteAddr
 		}
-
 		ipAddress = strings.Split(ipAddress, ":")[0]
 
+		// Check if this is the first time this IP address has visited
 		returnVisitor, err := dbConn.HasIPVisited(ipAddress)
 		if err != nil {
 			log.Printf("failed to determine if this is a return visitor, no data is being logged: %v", err)
@@ -97,9 +109,11 @@ func countHandler(w http.ResponseWriter, r *http.Request) {
 		}
 
 		if returnVisitor {
+			// Log their visit
 			err = dbConn.IncrementVisitor(ipAddress)
 			log.Printf("return visitor from %s", ipAddress)
 		} else {
+			// Insert a new visitor row in the database
 			err = dbConn.AddVisitor(ipAddress)
 			uniqueVisits++
 			log.Printf("new visitor from %s", ipAddress)
@@ -110,6 +124,7 @@ func countHandler(w http.ResponseWriter, r *http.Request) {
 		}
 
 	} else {
+		// Needs to be GET method
 		w.WriteHeader(http.StatusMethodNotAllowed)
 	}
 }