Rewrite: diff-generations command

This commit rewrites the diff-generation command completely.

The interface for the command changed, use -h to get the help text.
It supports system/user generation switching, stdout/stderr output and
verbosity now.

1 files changed, 109 insertions, 10 deletions

diff --git a/nix-script-diff-generations.sh b/nix-script-diff-generations.sh
index 8516e64..286159d 100755
--- a/nix-script-diff-generations.sh
+++ b/nix-script-diff-generations.sh
@@ -2,31 +2,130 @@
 
 Color_Off='\e[0m'
 Red='\e[0;31m'
+Green='\e[0;32m'
 
-if [[ -z "$1" || -z "$2" ]]
+usage() {
+    cat <<EOS
+    diff-generations [options] <generation a> <generation b>
+
+        -s       Use system generation for diffing
+        -u       Use system generation for diffing
+        -n a..b  Diff these generations
+        -v       Be verbose
+        -h       Show this help and exit
+
+EOS
+}
+
+__SYSTEM=0
+__USER=0
+
+GEN_A=
+GEN_B=
+
+stdout() {
+    [[ $VERBOSE -eq 1 ]] && echo -e "${Green}[$0]:${Color_Off} $*"
+}
+
+stderr() {
+    echo -e "${Red}$*${Color_Off}"
+}
+
+while getopts "sun:h" OPTION
+do
+    case $OPTION in
+
+        s)
+            stdout "Setting profile: system"
+            __SYSTEM=1
+            __USER=0
+            ;;
+
+        u)
+            stdout "Setting profile: user ($USER)"
+            __SYSTEM=0
+            __USER=1
+            ;;
+
+        n)
+            GEN_A=$(echo $OPTARG | cut -d "." -f 1)
+            GEN_B=$(echo $OPTARG | cut -d "." -f 3)
+
+            stdout "Parsing generations: $OPTARG"
+            stdout "Parsing generations: GEN_A: $GEN_A"
+            stdout "Parsing generations: GEN_B: $GEN_B"
+
+            if [[ -z "$GEN_A" || -z "$GEN_B" ]]
+            then
+                stderr "Parsing error for '$OPTARG'"
+                usage
+                exit 1
+            fi
+            ;;
+
+        h)
+            usage
+            exit 1
+            ;;
+    esac
+done
+
+gen_path() {
+    if [[ $__SYSTEM -eq 1 ]]
+    then
+        echo "/nix/var/nix/profiles/system-${1}-link"
+    fi
+
+    if [[ $__USER -eq 1 ]]
+    then
+        echo "/nix/var/nix/profiles/per-user/$USER/profile-${1}-link"
+    fi
+}
+
+DIR_A=$(gen_path $GEN_A)
+DIR_B=$(gen_path $GEN_B)
+
+stdout "VERBOSE         : $VERBOSE"
+stdout "SYSTEM          : $__SYSTEM"
+stdout "USER            : $__USER"
+stdout "Generation A    : $GEN_A"
+stdout "from directory  : $DIR_A"
+stdout "Generation B    : $GEN_B"
+stdout "from directory  : $DIR_B"
+
+if [[ ! -e $DIR_A ]]
 then
-    echo "Not enough arguments, expecting two numbers (generations)"
+    stderr "Generation $GEN_A does not exist."
     exit 1
 fi
 
-LOC=/nix/var/nix/profiles/per-user/$USER
-TYPE=profile
-
-DIR_A=$LOC/$TYPE-$1-link
-DIR_B=$LOC/$TYPE-$2-link
-
-if [[ ! -e $DIR_A || ! -e $DIR_B ]]
+if [[ ! -e $DIR_B ]]
 then
-    echo -e "${Red}Either generation $1 or $2 does not exist.${Color_Off}"
+    stderr "Generation $GEN_B does not exist."
     exit 1
 fi
 
 versA=$(mktemp)
+stdout "TMP file '$versA' created"
 nix-store -qR $DIR_A > $versA
+stdout "Generation packages written for $GEN_A"
+
 
 versB=$(mktemp)
+stdout "TMP file '$versB' created"
 nix-store -qR $DIR_B > $versB
+stdout "Generation packages written for $GEN_B"
+
+stdout "Diffing now..."
 
 diff -u $versA $versB | grep "nix/store" | sed 's:/nix/store/: :' | \
     grep -E "^(\+|\-).*" | sed -r 's:(.) ([a-z0-9]*)-(.*):\1 \3:' | \
         sort -k 1.44
+
+stdout "Removing tmp directories"
+
+rm $versA
+rm $versB
+
+stdout "Ready"
+