libfic: new way to handle exercice dependancies

libfic/team.go

@@ -6,8 +6,8 @@ import (
 	"time"
 )
 
-// UnlockedChallenges disables dependancy requirement between challenges.
-var UnlockedChallenges bool
+// UnlockedChallengeDepth is the number of challenges to unlock ahead (0: only the next one, -1: all)
+var UnlockedChallengeDepth int
 
 // WchoiceCoefficient is the current coefficient applied on the cost of changing flag into choices
 var WChoiceCoefficient = 1.0
@@ -99,14 +99,31 @@ func (t Team) Delete() (int64, error) {
 
 // HasAccess checks if the Team has access to the given challenge.
 func (t Team) HasAccess(e Exercice) bool {
-	if e.Depend == nil || UnlockedChallenges {
+	if UnlockedChallengeDepth < 0 {
 		return true
-	} else {
+	}
+
+	for i := UnlockedChallengeDepth; i >= 0; i-- {
+		// An exercice without dependency is accessible
+		if e.Depend == nil {
+			return true
+		}
+
 		ed := Exercice{}
 		ed.Id = *e.Depend
 		s, _ := t.HasSolved(ed)
-		return s
+		if s {
+			return s
+		}
+
+		// Prepare next iteration
+		var err error
+		e, err = GetExercice(ed.Id)
+		if err != nil {
+			return false
+		}
 	}
+	return false
 }
 
 // CanDownload checks if the Team has access to the given file.