@@ -3,10 +3,11 @@
 import (
 	iou "0dev.org/ioutil"
 	"fmt"
 	"io"
 	// "io/ioutil"
+	"bytes"
 	"os"
 	"sort"
 )
 
 func main() {
@@ -29,28 +30,48 @@
 	if err != nil {
 		os.Stderr.WriteString("Error while constructing application reader. " + err.Error())
 		os.Exit(1)
 	}
 
-	// count, err := io.Copy(ioutil.Discard, reader)
-	// if err != nil {
-	// 	os.Stderr.WriteString("Error while applying recommendations. " + err.Error())
-	// 	os.Exit(1)
-	// }
-	// fmt.Println(count)
-
-	_, err = io.Copy(os.Stdout, reader)
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, reader)
+	if err != nil {
+		os.Stderr.WriteString("Error while applying recommendations. " + err.Error())
+		os.Exit(1)
+	}
+
+	var in *bytes.Reader = bytes.NewReader(buf.Bytes())
+	rev, err := apply(rec.reverse(), in)
+	if err != nil {
+		os.Stderr.WriteString("Error while constructing application reader. " + err.Error())
+		os.Exit(1)
+	}
+
+	_, err = io.Copy(os.Stdout, rev)
 	if err != nil {
 		os.Stderr.WriteString("Error while applying recommendations. " + err.Error())
 		os.Exit(1)
 	}
 }
 
 type recommendation struct {
-	p2s      map[uint16]byte
-	s2p      map[byte]uint16
-	unmapped byte
+	p2s map[uint16]byte
+	s2p map[byte]uint16
+}
+
+// Produces a reversed recommendation struct
+func (r *recommendation) reverse() *recommendation {
+	var rec recommendation
+	rec.p2s = make(map[uint16]byte)
+	for k, v := range r.s2p {
+		rec.p2s[v] = k
+	}
+	rec.s2p = make(map[byte]uint16)
+	for k, v := range r.p2s {
+		rec.s2p[v] = k
+	}
+	return &rec
 }
 
 // Returns an io.Reader that reads from the underlying one while applying the given recommendations
 func apply(rec *recommendation, reader io.Reader) (io.Reader, error) {
 	// The symbol reader replaces symbols with pairs according to the s2p mapping
@@ -117,11 +138,11 @@
 
 	for i, pairsLength := 0, len(pairs); i < pairsLength; i++ {
 		currentPair := pairs[i]
 
 		// Termination condition for when we are out of symbols
-		if len(symbols) == 1 {
+		if len(symbols) == 1 { // TODO drop to zero ?
 			break
 		}
 
 		gain := currentPair.count - 4 // 4 bytes for the default header
 		currentSymbol := symbols[0]
@@ -150,11 +171,10 @@
 			// Mark the current pair for replacement by the current symbol
 			rec.p2s[currentPair.value] = currentSymbol.value
 		}
 		symbols = symbols[1:]
 	}
-	rec.unmapped = symbols[len(symbols)-1].value
 	return &rec
 }
 
 // Reads the provided input and returns information about the available byte pair and used symbols
 func analyze(reader io.Reader) (pairSlice, symbolSlice) {