refactor column config

config/columns.go

@@ -0,0 +1,138 @@
+package config
+
+import (
+	"strings"
+)
+
+// defaults
+var defaultColumns = []Column{
+	Column{
+		Name:    "status",
+		Label:   "Status Indicator",
+		Enabled: true,
+	},
+	Column{
+		Name:    "name",
+		Label:   "Container Name",
+		Enabled: true,
+	},
+	Column{
+		Name:    "id",
+		Label:   "Container ID",
+		Enabled: true,
+	},
+	Column{
+		Name:    "cpu",
+		Label:   "CPU Usage",
+		Enabled: true,
+	},
+	Column{
+		Name:    "mem",
+		Label:   "Memory Usage",
+		Enabled: true,
+	},
+	Column{
+		Name:    "net",
+		Label:   "Network RX/TX",
+		Enabled: true,
+	},
+	Column{
+		Name:    "io",
+		Label:   "Disk IO Read/Write",
+		Enabled: true,
+	},
+	Column{
+		Name:    "pids",
+		Label:   "Container PID Count",
+		Enabled: true,
+	},
+}
+
+type Column struct {
+	Name    string
+	Label   string
+	Enabled bool
+}
+
+// ColumnsString returns an ordered and comma-delimited string of currently enabled Columns
+func ColumnsString() string { return strings.Join(EnabledColumns(), ",") }
+
+// EnabledColumns returns an ordered array of enabled column names
+func EnabledColumns() (a []string) {
+	lock.RLock()
+	defer lock.RUnlock()
+	for _, col := range GlobalColumns {
+		if col.Enabled {
+			a = append(a, col.Name)
+		}
+	}
+	return a
+}
+
+// ColumnLeft moves the column with given name up one position, if possible
+func ColumnLeft(name string) {
+	idx := colIndex(name)
+	if idx > 0 {
+		swapCols(idx, idx-1)
+	}
+}
+
+// ColumnRight moves the column with given name up one position, if possible
+func ColumnRight(name string) {
+	idx := colIndex(name)
+	if idx < len(GlobalColumns)-1 {
+		swapCols(idx, idx+1)
+	}
+}
+
+// Set Column order and enabled status from one or more provided Column names
+func SetColumns(names []string) {
+	var (
+		n          int
+		curColStr  = ColumnsString()
+		newColumns = make([]*Column, len(GlobalColumns))
+	)
+
+	lock.Lock()
+
+	// add enabled columns by name
+	for _, name := range names {
+		newColumns[n] = popColumn(name)
+		newColumns[n].Enabled = true
+		n++
+	}
+
+	// extend with omitted columns as disabled
+	for _, col := range GlobalColumns {
+		newColumns[n] = col
+		newColumns[n].Enabled = false
+		n++
+	}
+
+	GlobalColumns = newColumns
+	lock.Unlock()
+
+	log.Noticef("config change [columns]: %s -> %s", curColStr, ColumnsString())
+}
+
+func swapCols(i, j int) { GlobalColumns[i], GlobalColumns[j] = GlobalColumns[j], GlobalColumns[i] }
+
+func popColumn(name string) *Column {
+	idx := colIndex(name)
+	if idx < 0 {
+		panic("no such column name: " + name)
+	}
+	col := GlobalColumns[idx]
+	GlobalColumns = append(GlobalColumns[:idx], GlobalColumns[idx+1:]...)
+	return col
+}
+
+// return index of column with given name, if any
+func colIndex(name string) int {
+	for n, c := range GlobalColumns {
+		if c.Name == name {
+			return n
+		}
+	}
+	return -1
+}