#include "unity.h"
#include "bintree.h"
#include <stdlib.h>
#include <string.h>

/* ============================================================================
 * UNIT TESTS FOR BINARY SEARCH TREE IMPLEMENTATION (Binärer Suchbaum)
 * 
 * This test suite covers all four functions:
 * - addToTree(): Insert elements maintaining BST ordering
 * - clearTree(): Free all memory in the tree
 * - treeSize(): Count nodes in the tree
 * - nextTreeData(): In-order traversal using stack
 * ========================================================================== */

// ============================================================================
// HELPER FUNCTIONS FOR TESTING
// ============================================================================

// Comparison function for integers (ascending order: smaller values first)
// Returns: <0 if a < b, 0 if a == b, >0 if a > b
int compareIntegers(const void *a, const void *b)
{
    int valA = *(const int *)a;
    int valB = *(const int *)b;
    return valA - valB;
}

// Comparison function for strings (alphabetical order)
int compareStrings(const void *a, const void *b)
{
    return strcmp((const char *)a, (const char *)b);
}

// ============================================================================
// TEST SETUP AND TEARDOWN
// ============================================================================

void setUp(void)
{
    // Perform any setup needed before each test
}

void tearDown(void)
{
    // Perform any cleanup needed after each test
    // Individual tests are responsible for clearing their trees
}

// ============================================================================
// TEST SUITE 1: addToTree() - Inserting Elements
// ============================================================================

// Test 1.1: Insert a single element into an empty tree (NULL root)
void test_addToTree_SingleElement(void)
{
    TreeNode *root = NULL;
    int value = 42;
    int isDuplicate = 0;
    
    // Insert the first element into an empty tree
    root = addToTree(root, &value, sizeof(int), compareIntegers, &isDuplicate);
    
    // Verify the root is not NULL
    TEST_ASSERT_NOT_NULL(root);
    
    // Verify the data was copied correctly
    TEST_ASSERT_EQUAL_INT(42, *(int *)root->data);
    
    // Verify isDuplicate was set to 0 (new entry added)
    TEST_ASSERT_EQUAL_INT(0, isDuplicate);
    
    // Verify the node has no children
    TEST_ASSERT_NULL(root->left);
    TEST_ASSERT_NULL(root->right);
    
    // Cleanup
    clearTree(root);
}

// Test 1.2: Insert multiple elements in ascending order
void test_addToTree_AscendingOrder(void)
{
    TreeNode *root = NULL;
    int values[] = {10, 20, 30};
    
    // Insert values in ascending order
    for (int i = 0; i < 3; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    // Verify root value
    TEST_ASSERT_EQUAL_INT(10, *(int *)root->data);
    
    // Verify each value goes to the right (since they're ascending)
    TEST_ASSERT_NULL(root->left);
    TEST_ASSERT_NOT_NULL(root->right);
    TEST_ASSERT_EQUAL_INT(20, *(int *)root->right->data);
    
    TEST_ASSERT_NULL(root->right->left);
    TEST_ASSERT_NOT_NULL(root->right->right);
    TEST_ASSERT_EQUAL_INT(30, *(int *)root->right->right->data);
    
    // Cleanup
    clearTree(root);
}

// Test 1.3: Insert multiple elements in descending order
void test_addToTree_DescendingOrder(void)
{
    TreeNode *root = NULL;
    int values[] = {30, 20, 10};
    
    // Insert values in descending order
    for (int i = 0; i < 3; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    // Verify root value
    TEST_ASSERT_EQUAL_INT(30, *(int *)root->data);
    
    // Verify each value goes to the left (since they're descending)
    TEST_ASSERT_NULL(root->right);
    TEST_ASSERT_NOT_NULL(root->left);
    TEST_ASSERT_EQUAL_INT(20, *(int *)root->left->data);
    
    TEST_ASSERT_NULL(root->left->right);
    TEST_ASSERT_NOT_NULL(root->left->left);
    TEST_ASSERT_EQUAL_INT(10, *(int *)root->left->left->data);
    
    // Cleanup
    clearTree(root);
}

// Test 1.4: Insert elements in balanced order (creating a balanced tree)
void test_addToTree_BalancedTree(void)
{
    TreeNode *root = NULL;
    int values[] = {20, 10, 30, 5, 15, 25, 35};
    
    // Insert values to create a somewhat balanced tree
    for (int i = 0; i < 7; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    // Verify root value
    TEST_ASSERT_EQUAL_INT(20, *(int *)root->data);
    
    // Verify left subtree
    TEST_ASSERT_EQUAL_INT(10, *(int *)root->left->data);
    TEST_ASSERT_EQUAL_INT(5, *(int *)root->left->left->data);
    TEST_ASSERT_EQUAL_INT(15, *(int *)root->left->right->data);
    
    // Verify right subtree
    TEST_ASSERT_EQUAL_INT(30, *(int *)root->right->data);
    TEST_ASSERT_EQUAL_INT(25, *(int *)root->right->left->data);
    TEST_ASSERT_EQUAL_INT(35, *(int *)root->right->right->data);
    
    // Cleanup
    clearTree(root);
}

// Test 1.5: Attempt to insert a duplicate when isDuplicate is NULL (allows duplicates)
void test_addToTree_AllowDuplicates(void)
{
    TreeNode *root = NULL;
    int value1 = 42;
    int value2 = 42;
    
    // Insert first instance
    root = addToTree(root, &value1, sizeof(int), compareIntegers, NULL);
    
    // Insert duplicate (isDuplicate is NULL, so duplicates are allowed)
    root = addToTree(root, &value2, sizeof(int), compareIntegers, NULL);
    
    // Verify tree has both entries (duplicate goes right)
    TEST_ASSERT_EQUAL_INT(42, *(int *)root->data);
    TEST_ASSERT_NULL(root->left);
    TEST_ASSERT_NOT_NULL(root->right);
    TEST_ASSERT_EQUAL_INT(42, *(int *)root->right->data);
    
    // Cleanup
    clearTree(root);
}

// Test 1.6: Attempt to insert a duplicate when isDuplicate is provided (rejects duplicates)
void test_addToTree_RejectDuplicates(void)
{
    TreeNode *root = NULL;
    int value1 = 42;
    int value2 = 42;
    int isDuplicate = 0;
    
    // Insert first instance
    root = addToTree(root, &value1, sizeof(int), compareIntegers, &isDuplicate);
    TEST_ASSERT_EQUAL_INT(0, isDuplicate);
    
    // Attempt to insert duplicate
    root = addToTree(root, &value2, sizeof(int), compareIntegers, &isDuplicate);
    
    // Verify isDuplicate was set to 1
    TEST_ASSERT_EQUAL_INT(1, isDuplicate);
    
    // Verify tree still has only one node with the first value
    TEST_ASSERT_EQUAL_INT(42, *(int *)root->data);
    TEST_ASSERT_NULL(root->left);
    TEST_ASSERT_NULL(root->right);
    
    // Cleanup
    clearTree(root);
}

// Test 1.7: Insert multiple elements with duplicate detection
void test_addToTree_MultipleWithDuplicateDetection(void)
{
    TreeNode *root = NULL;
    int values[] = {20, 10, 30, 10};  // 10 is a duplicate
    int isDuplicate = 0;
    
    // Insert 20
    root = addToTree(root, &values[0], sizeof(int), compareIntegers, &isDuplicate);
    TEST_ASSERT_EQUAL_INT(0, isDuplicate);
    
    // Insert 10 (new)
    root = addToTree(root, &values[1], sizeof(int), compareIntegers, &isDuplicate);
    TEST_ASSERT_EQUAL_INT(0, isDuplicate);
    
    // Insert 30 (new)
    root = addToTree(root, &values[2], sizeof(int), compareIntegers, &isDuplicate);
    TEST_ASSERT_EQUAL_INT(0, isDuplicate);
    
    // Insert 10 (duplicate)
    root = addToTree(root, &values[3], sizeof(int), compareIntegers, &isDuplicate);
    TEST_ASSERT_EQUAL_INT(1, isDuplicate);
    
    // Verify tree structure hasn't changed (3 nodes, not 4)
    TEST_ASSERT_EQUAL_INT(3, treeSize(root));
    
    // Cleanup
    clearTree(root);
}

// Test 1.8: Insert strings into a tree
void test_addToTree_WithStrings(void)
{
    TreeNode *root = NULL;
    const char *words[] = {"dog", "cat", "elephant", "bear"};
    
    // Insert strings
    for (int i = 0; i < 4; i++)
    {
        // Note: We pass pointer to the string pointer
        root = addToTree(root, &words[i], sizeof(char *), compareStrings, NULL);
    }
    
    // Verify root value (first insertion)
    TEST_ASSERT_EQUAL_STRING("dog", *(char **)root->data);
    
    // Verify tree has 4 nodes
    TEST_ASSERT_EQUAL_INT(4, treeSize(root));
    
    // Cleanup
    clearTree(root);
}

// ============================================================================
// TEST SUITE 2: treeSize() - Counting Nodes
// ============================================================================

// Test 2.1: Size of empty tree (NULL root)
void test_treeSize_EmptyTree(void)
{
    TreeNode *root = NULL;
    unsigned int size = treeSize(root);
    
    // Verify empty tree has size 0
    TEST_ASSERT_EQUAL_INT(0, size);
}

// Test 2.2: Size of single-node tree
void test_treeSize_SingleNode(void)
{
    TreeNode *root = NULL;
    int value = 42;
    
    root = addToTree(root, &value, sizeof(int), compareIntegers, NULL);
    unsigned int size = treeSize(root);
    
    // Verify single-node tree has size 1
    TEST_ASSERT_EQUAL_INT(1, size);
    
    clearTree(root);
}

// Test 2.2: Size of multi-node tree
void test_treeSize_MultipleNodes(void)
{
    TreeNode *root = NULL;
    int values[] = {20, 10, 30, 5, 15, 25, 35};
    
    // Insert all values
    for (int i = 0; i < 7; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    unsigned int size = treeSize(root);
    
    // Verify tree has 7 nodes
    TEST_ASSERT_EQUAL_INT(7, size);
    
    clearTree(root);
}

// Test 2.3: Size after multiple insertions
void test_treeSize_IncrementalGrowth(void)
{
    TreeNode *root = NULL;
    int values[] = {20, 10, 30, 5, 15};
    
    for (int i = 0; i < 5; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
        
        // Check size increases with each insertion
        unsigned int expectedSize = i + 1;
        TEST_ASSERT_EQUAL_INT(expectedSize, treeSize(root));
    }
    
    clearTree(root);
}

// ============================================================================
// TEST SUITE 3: clearTree() - Freeing Memory
// ============================================================================

// Test 3.1: Clear empty tree (NULL root)
void test_clearTree_EmptyTree(void)
{
    TreeNode *root = NULL;
    
    // Should not crash when clearing NULL
    clearTree(root);
    
    // Verify still NULL after clearing
    TEST_ASSERT_NULL(root);
}

// Test 3.2: Clear single-node tree
void test_clearTree_SingleNode(void)
{
    TreeNode *root = NULL;
    int value = 42;
    
    root = addToTree(root, &value, sizeof(int), compareIntegers, NULL);
    
    // Clear the tree
    clearTree(root);
    root = NULL;  // Reset pointer
    
    // Verify root is now NULL
    TEST_ASSERT_NULL(root);
}

// Test 3.3: Clear multi-node tree
void test_clearTree_MultipleNodes(void)
{
    TreeNode *root = NULL;
    int values[] = {20, 10, 30, 5, 15, 25, 35};
    
    for (int i = 0; i < 7; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    // Clear the entire tree
    clearTree(root);
    root = NULL;
    
    // Verify root is now NULL
    TEST_ASSERT_NULL(root);
    
    // If we got here without segfault, the memory was properly freed
}

// ============================================================================
// TEST SUITE 4: nextTreeData() - In-Order Traversal
// ============================================================================

// Test 4.1: In-order traversal of simple tree (ascending linear)
void test_nextTreeData_AscendingLinearTree(void)
{
    TreeNode *root = NULL;
    int values[] = {1, 2, 3};
    
    for (int i = 0; i < 3; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    // Traverse and collect results
    int result1 = *(int *)nextTreeData(root);
    int result2 = *(int *)nextTreeData(NULL);
    int result3 = *(int *)nextTreeData(NULL);
    void *result4 = nextTreeData(NULL);
    
    // Verify in-order traversal produces ascending order
    TEST_ASSERT_EQUAL_INT(1, result1);
    TEST_ASSERT_EQUAL_INT(2, result2);
    TEST_ASSERT_EQUAL_INT(3, result3);
    TEST_ASSERT_NULL(result4);  // No more elements
    
    clearTree(root);
}

// Test 4.2: In-order traversal of balanced tree
void test_nextTreeData_BalancedTree(void)
{
    TreeNode *root = NULL;
    int values[] = {20, 10, 30, 5, 15, 25, 35};
    
    for (int i = 0; i < 7; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    // Traverse and collect results
    int results[7];
    results[0] = *(int *)nextTreeData(root);
    for (int i = 1; i < 7; i++)
    {
        results[i] = *(int *)nextTreeData(NULL);
    }
    
    // Verify in-order traversal produces ascending order
    int expectedOrder[] = {5, 10, 15, 20, 25, 30, 35};
    for (int i = 0; i < 7; i++)
    {
        TEST_ASSERT_EQUAL_INT(expectedOrder[i], results[i]);
    }
    
    // Verify traversal is complete
    void *result = nextTreeData(NULL);
    TEST_ASSERT_NULL(result);
    
    clearTree(root);
}

// Test 4.3: In-order traversal of descending linear tree
void test_nextTreeData_DescendingLinearTree(void)
{
    TreeNode *root = NULL;
    int values[] = {30, 20, 10};
    
    for (int i = 0; i < 3; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, NULL);
    }
    
    // Traverse and collect results
    int result1 = *(int *)nextTreeData(root);
    int result2 = *(int *)nextTreeData(NULL);
    int result3 = *(int *)nextTreeData(NULL);
    void *result4 = nextTreeData(NULL);
    
    // Verify in-order traversal produces ascending order (despite insertion order)
    TEST_ASSERT_EQUAL_INT(10, result1);
    TEST_ASSERT_EQUAL_INT(20, result2);
    TEST_ASSERT_EQUAL_INT(30, result3);
    TEST_ASSERT_NULL(result4);
    
    clearTree(root);
}

// Test 4.4: Traversal of single-node tree
void test_nextTreeData_SingleNode(void)
{
    TreeNode *root = NULL;
    int value = 42;
    
    root = addToTree(root, &value, sizeof(int), compareIntegers, NULL);
    
    int result1 = *(int *)nextTreeData(root);
    void *result2 = nextTreeData(NULL);
    
    TEST_ASSERT_EQUAL_INT(42, result1);
    TEST_ASSERT_NULL(result2);
    
    clearTree(root);
}

// Test 4.5: Traversal of empty tree
void test_nextTreeData_EmptyTree(void)
{
    TreeNode *root = NULL;
    
    void *result = nextTreeData(root);
    
    TEST_ASSERT_NULL(result);
}

// ============================================================================
// INTEGRATION TEST: Complete BST Workflow
// ============================================================================

// Test 5.1: Complete workflow - insert, size, traverse, clear
void test_integration_CompleteWorkflow(void)
{
    TreeNode *root = NULL;
    int values[] = {50, 25, 75, 12, 37, 62, 87};
    int isDuplicate = 0;
    
    // Insert all values
    for (int i = 0; i < 7; i++)
    {
        root = addToTree(root, &values[i], sizeof(int), compareIntegers, &isDuplicate);
        TEST_ASSERT_EQUAL_INT(0, isDuplicate);
    }
    
    // Verify size
    TEST_ASSERT_EQUAL_INT(7, treeSize(root));
    
    // Verify in-order traversal
    int expectedOrder[] = {12, 25, 37, 50, 62, 75, 87};
    int results[7];
    
    results[0] = *(int *)nextTreeData(root);
    for (int i = 1; i < 7; i++)
    {
        results[i] = *(int *)nextTreeData(NULL);
    }
    
    for (int i = 0; i < 7; i++)
    {
        TEST_ASSERT_EQUAL_INT(expectedOrder[i], results[i]);
    }
    
    // Verify duplicate detection
    root = addToTree(root, &values[0], sizeof(int), compareIntegers, &isDuplicate);
    TEST_ASSERT_EQUAL_INT(1, isDuplicate);
    TEST_ASSERT_EQUAL_INT(7, treeSize(root));  // Size should not increase
    
    // Clear and verify
    clearTree(root);
    root = NULL;
    TEST_ASSERT_NULL(root);
}

// ============================================================================
// TEST RUNNER
// ============================================================================

int main(void)
{
    UNITY_BEGIN();
    
    // Test Suite 1: addToTree()
    RUN_TEST(test_addToTree_SingleElement);
    RUN_TEST(test_addToTree_AscendingOrder);
    RUN_TEST(test_addToTree_DescendingOrder);
    RUN_TEST(test_addToTree_BalancedTree);
    RUN_TEST(test_addToTree_AllowDuplicates);
    RUN_TEST(test_addToTree_RejectDuplicates);
    RUN_TEST(test_addToTree_MultipleWithDuplicateDetection);
    RUN_TEST(test_addToTree_WithStrings);
    
    // Test Suite 2: treeSize()
    RUN_TEST(test_treeSize_EmptyTree);
    RUN_TEST(test_treeSize_SingleNode);
    RUN_TEST(test_treeSize_MultipleNodes);
    RUN_TEST(test_treeSize_IncrementalGrowth);
    
    // Test Suite 3: clearTree()
    RUN_TEST(test_clearTree_EmptyTree);
    RUN_TEST(test_clearTree_SingleNode);
    RUN_TEST(test_clearTree_MultipleNodes);
    
    // Test Suite 4: nextTreeData()
    RUN_TEST(test_nextTreeData_AscendingLinearTree);
    RUN_TEST(test_nextTreeData_BalancedTree);
    RUN_TEST(test_nextTreeData_DescendingLinearTree);
    RUN_TEST(test_nextTreeData_SingleNode);
    RUN_TEST(test_nextTreeData_EmptyTree);
    
    // Integration Test
    RUN_TEST(test_integration_CompleteWorkflow);
    
    return UNITY_END();
}