From e7914f281d751a60e67b2d5d941cd3cb3eb2e09e Mon Sep 17 00:00:00 2001
From: Sebastian Morr <sebastian@morr.cc>
Date: Tue, 15 Sep 2020 16:32:00 +0200
Subject: [PATCH] Two new low-level levels

---
 levels/commit-rhombus/description |  5 +++++
 levels/commit-rhombus/start       |  5 +++++
 levels/commit-rhombus/win         | 10 ++++++++++
 levels/tree-nested/description    |  5 +++++
 levels/tree-nested/goal           |  7 +++++++
 levels/tree-nested/start          |  0
 levels/tree-nested/win            | 16 ++++++++++++++++
 7 files changed, 48 insertions(+)
 create mode 100644 levels/commit-rhombus/description
 create mode 100644 levels/commit-rhombus/start
 create mode 100644 levels/commit-rhombus/win
 create mode 100644 levels/tree-nested/description
 create mode 100644 levels/tree-nested/goal
 create mode 100644 levels/tree-nested/start
 create mode 100644 levels/tree-nested/win

diff --git a/levels/commit-rhombus/description b/levels/commit-rhombus/description
new file mode 100644
index 0000000..acf8162
--- /dev/null
+++ b/levels/commit-rhombus/description
@@ -0,0 +1,5 @@
+A commit can have multiple parents! You can specify the -p option multiple times, like this:
+
+    git commit-tree <tree> -m "Description" -p <parent1> -p <parent2>
+
+Build a rhombus shape from commits, where two commits point to the same parent, and then a fourth commit points to both of them.
diff --git a/levels/commit-rhombus/start b/levels/commit-rhombus/start
new file mode 100644
index 0000000..f74e07d
--- /dev/null
+++ b/levels/commit-rhombus/start
@@ -0,0 +1,5 @@
+TREE=$(git write-tree)
+SOUTH=$(git commit-tree $TREE -m "South")
+EAST=$(git commit-tree $TREE -m "East" -p $SOUTH)
+WEST=$(git commit-tree $TREE -m "West" -p $SOUTH)
+NORTH=$(git commit-tree $TREE -m "Nort" -p $EAST -p $WEST)
diff --git a/levels/commit-rhombus/win b/levels/commit-rhombus/win
new file mode 100644
index 0000000..2364153
--- /dev/null
+++ b/levels/commit-rhombus/win
@@ -0,0 +1,10 @@
+COMMITS=$(git cat-file --batch-check='%(objectname) %(objecttype)' --batch-all-objects | grep commit | cut -f1 -d" ")
+
+for COMMIT in $COMMITS; do
+    # My first parent's parents has to be the same as my second parent's parent.
+    if [ "$(git rev-parse --verify -q $COMMIT^1^)" = "$(git rev-parse --verify -q $COMMIT^2^)" ]; then
+        exit 0
+    fi
+done
+
+exit 1
diff --git a/levels/tree-nested/description b/levels/tree-nested/description
new file mode 100644
index 0000000..8a30ffc
--- /dev/null
+++ b/levels/tree-nested/description
@@ -0,0 +1,5 @@
+Trees can also point to other trees! This way, they can basically describe nested directory structures.
+
+When you add a file inside of a directory to the index, and then call `git write-tree`, it will automatically do the correct thing.
+
+To solve this level, build a little stick figure, as shown on the left - a tree that points to two blobs, and to a tree that points to two blobs.
diff --git a/levels/tree-nested/goal b/levels/tree-nested/goal
new file mode 100644
index 0000000..dfb9bef
--- /dev/null
+++ b/levels/tree-nested/goal
@@ -0,0 +1,7 @@
+echo "I'm the left arm" > arm1
+echo "I'm the right arm" > arm2
+mkdir hip
+echo "I'm the left leg" > hip/leg1
+echo "I'm the right leg" > hip/leg2
+git add .
+git write-tree
diff --git a/levels/tree-nested/start b/levels/tree-nested/start
new file mode 100644
index 0000000..e69de29
diff --git a/levels/tree-nested/win b/levels/tree-nested/win
new file mode 100644
index 0000000..e0cc491
--- /dev/null
+++ b/levels/tree-nested/win
@@ -0,0 +1,16 @@
+TREES=$(git cat-file --batch-check='%(objectname) %(objecttype)' --batch-all-objects | grep tree | cut -f1 -d" ")
+
+for OUTER_TREE in $TREES; do
+    NUMBER_OF_BLOB_CHILDREN=$(git cat-file -p $OUTER_TREE | cut -f2 -d" " | grep blob | wc -l)
+    NUMBER_OF_TREE_CHILDREN=$(git cat-file -p $OUTER_TREE | cut -f2 -d" " | grep tree | wc -l)
+
+    if [ $NUMBER_OF_BLOB_CHILDREN -eq 2 -a $NUMBER_OF_TREE_CHILDREN -eq 1 ]; then
+        TREE_CHILD=$(git cat-file -p $OUTER_TREE | cut -f1 | grep tree | cut -d" " -f3)
+        NUMBER_OF_BLOB_CHILDREN_OF_TREE_CHILD=$(git cat-file -p $TREE_CHILD | cut -f2 -d" " | grep blob | wc -l)
+        if [ $NUMBER_OF_BLOB_CHILDREN_OF_TREE_CHILD -eq 2 ]; then
+            exit 0
+        fi
+    fi
+done
+
+exit 1