From 47d569e3fc762a437674e0a854cd235c6e005924 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Tue, 30 Apr 2019 16:15:45 -0400
Subject: [PATCH] Step 11

---
 db.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/db.c b/db.c
index bbdff91..99363d1 100644
--- a/db.c
+++ b/db.c
@@ -352,6 +352,34 @@ Cursor* leaf_node_find(Table* table, uint32_t page_num, uint32_t key) {
     return cursor;
 }
 
+Cursor* internal_node_find(Table* table, uint32_t page_num, uint32_t key) {
+    void* node = get_page(table->pager, page_num);
+    uint32_t num_keys = *internal_node_num_keys(node);
+
+    /* Binary search to find index of child to search */
+    uint32_t min_index = 0;
+    uint32_t max_index = num_keys; /* there is one more child than key */
+
+    while (min_index != max_index) {
+        uint32_t index = (min_index + max_index) / 2;
+        uint32_t key_to_right = *internal_node_key(node, index);
+        if (key_to_right >= key) {
+            max_index = index;
+        } else {
+            min_index = index + 1;
+        }
+    }
+
+    uint32_t child_num = *internal_node_child(node, min_index);
+    void* child = get_page(table->pager, child_num);
+    switch (get_node_type(child)) {
+        case NODE_LEAF:
+            return leaf_node_find(table, child_num, key);
+        case NODE_INTERNAL:
+            return internal_node_find(table, child_num, key);
+    }
+}
+
 /*
  * Return the position of the given key.
  * If the key is not present, return the position
@@ -364,8 +392,7 @@ Cursor* table_find(Table* table, uint32_t key) {
     if (get_node_type(root_node) == NODE_LEAF) {
         return leaf_node_find(table, root_page_num, key);
     } else {
-        printf("Need to implement searching an internal node\n");
-        exit(EXIT_FAILURE);
+        return internal_node_find(table, root_page_num, key);
     }
 }