added water sensor library

sensor/watersensor/watersensor.go

@@ -0,0 +1,64 @@
+package watersensor
+
+import (
+        "log"
+        "sync"
+        "github.com/stianeikeland/go-rpio"
+       )
+
+type watersensor struct {
+    waterPinNumber int
+        waterPin rpio.Pin
+        initialized bool
+        mu *sync.RWMutex
+        debug bool
+}
+
+type WaterSensor interface {
+    IsWet() (b bool,err error)
+}
+
+func New(pinNumber int) WaterSensor {
+    return &watersensor{waterPinNumber: pinNumber, mu: new(sync.RWMutex)}
+}
+
+func (d *watersensor) Setup() (err error) {
+    d.mu.RLock()
+        if d.initialized {
+            d.mu.RUnlock()
+                return
+        }
+    d.mu.RUnlock()
+
+        d.mu.Lock()
+        defer d.mu.Unlock()
+
+        if err = rpio.Open(); err != nil {
+            return
+        }
+    d.waterPin = rpio.Pin(d.waterPinNumber)
+
+        d.waterPin.Input()
+
+        d.initialized = true
+
+        return nil
+}
+
+func (d *watersensor) IsWet() (b bool, err error) {
+    if err = d.Setup(); err != nil {
+        return
+    }
+
+    if d.debug {
+        log.Print("Getting reading")
+    }
+
+    if d.waterPin.Read() == rpio.High {
+        b=true
+    } else {
+        b=false
+    }
+
+    return
+}