#include "unity.h"
#include "numbers.h"
#include <stdlib.h>
#include <string.h>
#include <time.h>

/* ============================================================================
 * UNIT TESTS FOR SORTING AND DUPLICATE DETECTION (Sortierung)
 * 
 * This test suite covers:
 * - createNumbers(): Generate random numbers with exactly one duplicate
 * - getDuplicate(): Find the duplicate number using sorting
 * ========================================================================== */

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

// Count how many times a specific value appears in an array
unsigned int countOccurrences(const unsigned int *numbers, unsigned int len, unsigned int value)
{
    unsigned int count = 0;
    for (unsigned int i = 0; i < len; i++)
    {
        if (numbers[i] == value)
        {
            count++;
        }
    }
    return count;
}

// Check if a value is in the valid range [1, 2*len]
int isInValidRange(unsigned int value, unsigned int len)
{
    return (value >= 1) && (value <= 2 * len);
}

// Count total number of distinct values in the array
unsigned int countDistinctValues(const unsigned int *numbers, unsigned int len)
{
    unsigned int distinct = 0;
    for (unsigned int i = 0; i < len; i++)
    {
        int isNew = 1;
        for (unsigned int j = 0; j < i; j++)
        {
            if (numbers[i] == numbers[j])
            {
                isNew = 0;
                break;
            }
        }
        if (isNew)
        {
            distinct++;
        }
    }
    return distinct;
}

// Find the value that appears exactly twice
unsigned int findDuplicate(const unsigned int *numbers, unsigned int len)
{
    for (unsigned int i = 0; i < len; i++)
    {
        unsigned int count = countOccurrences(numbers, len, numbers[i]);
        if (count == 2)
        {
            return numbers[i];
        }
    }
    return 0;  // No duplicate found
}

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

void setUp(void)
{
    // Setup before each test
}

void tearDown(void)
{
    // Cleanup after each test
}

// ============================================================================
// TEST SUITE 1: createNumbers() - Input Validation and Error Handling
// ============================================================================

// Test 1.1: Invalid input - len = 0 should return NULL
void test_createNumbers_InvalidLenZero(void)
{
    unsigned int *numbers = createNumbers(0);
    
    TEST_ASSERT_NULL(numbers);
}

// Test 1.2: Invalid input - len = 1 should return NULL (need at least 2 for duplicate)
void test_createNumbers_InvalidLenOne(void)
{
    unsigned int *numbers = createNumbers(1);
    
    TEST_ASSERT_NULL(numbers);
}

// ============================================================================
// TEST SUITE 2: createNumbers() - Minimum Valid Input
// ============================================================================

// Test 2.1: Minimum valid input - len = 2
void test_createNumbers_MinimumSize(void)
{
    unsigned int *numbers = createNumbers(2);
    
    // Should not be NULL
    TEST_ASSERT_NOT_NULL(numbers);
    
    // One value should equal the other (the duplicate)
    TEST_ASSERT_EQUAL_INT(numbers[0], numbers[1]);
    
    free(numbers);
}

// ============================================================================
// TEST SUITE 3: createNumbers() - Array Size and Contents
// ============================================================================

// Test 3.1: Check array size for len=5
void test_createNumbers_ArraySize5(void)
{
    unsigned int *numbers = createNumbers(5);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Access all 5 elements to verify they exist
    for (unsigned int i = 0; i < 5; i++)
    {
        // Just verify we can read without segfault
        (void)numbers[i];
    }
    
    free(numbers);
}

// Test 3.2: Check array size for len=10
void test_createNumbers_ArraySize10(void)
{
    unsigned int *numbers = createNumbers(10);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Access all 10 elements
    for (unsigned int i = 0; i < 10; i++)
    {
        // Just verify we can read without segfault
        (void)numbers[i];
    }
    
    free(numbers);
}

// ============================================================================
// TEST SUITE 4: createNumbers() - Value Range Validation
// ============================================================================

// Test 4.1: All values are positive (basic sanity check)
void test_createNumbers_ValueRangeLen5(void)
{
    unsigned int *numbers = createNumbers(5);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Check each value is positive and not too large
    for (unsigned int i = 0; i < 5; i++)
    {
        TEST_ASSERT_TRUE(numbers[i] > 0);
        TEST_ASSERT_TRUE(numbers[i] <= 10);
    }
    
    free(numbers);
}

// Test 4.2: All values are positive (for len=20)
void test_createNumbers_ValueRangeLen20(void)
{
    unsigned int *numbers = createNumbers(20);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Check each value is positive and reasonable
    for (unsigned int i = 0; i < 20; i++)
    {
        TEST_ASSERT_TRUE(numbers[i] > 0);
        TEST_ASSERT_TRUE(numbers[i] <= 40);
    }
    
    free(numbers);
}

// ============================================================================
// TEST SUITE 5: createNumbers() - Duplicate Detection
// ============================================================================

// Test 5.1: Exactly one value appears twice (len=5)
void test_createNumbers_ExactlyOneDuplicateLen5(void)
{
    unsigned int *numbers = createNumbers(5);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Count how many distinct values appear exactly twice
    unsigned int valuesAppearingTwice = 0;
    unsigned int counted[5] = {0};  // Track which values we've counted
    
    for (unsigned int i = 0; i < 5; i++)
    {
        unsigned int value = numbers[i];
        unsigned int count = countOccurrences(numbers, 5, value);
        
        // If this value appears twice and we haven't counted it yet, count it now
        if (count == 2)
        {
            int alreadyCounted = 0;
            for (unsigned int j = 0; j < 5; j++)
            {
                if (counted[j] == value)
                {
                    alreadyCounted = 1;
                    break;
                }
            }
            
            if (!alreadyCounted)
            {
                valuesAppearingTwice++;
                counted[i] = value;  // Mark this value as counted
            }
        }
    }
    
    // Should have exactly one value that appears twice
    TEST_ASSERT_EQUAL_INT(1, valuesAppearingTwice);
    
    // Count distinct values - should be len-1 = 4
    unsigned int distinct = countDistinctValues(numbers, 5);
    TEST_ASSERT_EQUAL_INT(4, distinct);
    
    free(numbers);
}

// Test 5.2: Exactly one value appears twice (len=10)
void test_createNumbers_ExactlyOneDuplicateLen10(void)
{
    unsigned int *numbers = createNumbers(10);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Count how many distinct values appear exactly twice
    unsigned int valuesAppearingTwice = 0;
    unsigned int counted[10] = {0};  // Track which values we've counted
    
    for (unsigned int i = 0; i < 10; i++)
    {
        unsigned int value = numbers[i];
        unsigned int count = countOccurrences(numbers, 10, value);
        
        // If this value appears twice and we haven't counted it yet, count it now
        if (count == 2)
        {
            int alreadyCounted = 0;
            for (unsigned int j = 0; j < 10; j++)
            {
                if (counted[j] == value)
                {
                    alreadyCounted = 1;
                    break;
                }
            }
            
            if (!alreadyCounted)
            {
                valuesAppearingTwice++;
                counted[i] = value;  // Mark this value as counted
            }
        }
    }
    
    // Should have exactly one value that appears twice
    TEST_ASSERT_EQUAL_INT(1, valuesAppearingTwice);
    
    // Count distinct values - should be len-1 = 9
    unsigned int distinct = countDistinctValues(numbers, 10);
    TEST_ASSERT_EQUAL_INT(9, distinct);
    
    free(numbers);
}

// Test 5.3: No accidental triplicates (len=5)
void test_createNumbers_NoTriplicatesLen5(void)
{
    unsigned int *numbers = createNumbers(5);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Count occurrences of each value
    for (unsigned int i = 0; i < 5; i++)
    {
        unsigned int count = countOccurrences(numbers, 5, numbers[i]);
        
        // Each value should appear 1 or 2 times, never 3 or more
        TEST_ASSERT_TRUE(count == 1 || count == 2);
    }
    
    free(numbers);
}

// ============================================================================
// TEST SUITE 6: createNumbers() - No Accidental Duplicates Before Intentional One
// ============================================================================

// Test 6.1: Total count validation - sum should be len
void test_createNumbers_TotalCountLen5(void)
{
    unsigned int *numbers = createNumbers(5);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Sum of all occurrences should equal len (5)
    // (unique_count * 1) + (1 duplicate_value * 2) = len
    // which simplifies to: (len-1) + 2 = len + 1 ... wait that's wrong
    
    // Actually: if we have 4 unique values and 1 appears twice:
    // 4 unique values, but 1 of them appears twice
    // So: 3 values appearing once + 1 value appearing twice = 3 + 2 = 5 total entries
    
    // Total unique values = len - 1 = 4
    // But sum of elements = len = 5
    // This checks out: (len-1-1) * 1 + 1 * 2 = (len-2) + 2 = len ✓
    
    unsigned int distinct = countDistinctValues(numbers, 5);
    TEST_ASSERT_EQUAL_INT(4, distinct);
    
    free(numbers);
}

// ============================================================================
// TEST SUITE 7: createNumbers() - Randomness
// ============================================================================

// Test 7.1: Multiple calls produce different (or can produce different) results
void test_createNumbers_DifferentRandomResults(void)
{
    unsigned int *numbers1 = createNumbers(5);
    
    // Advance the random sequence a bit
    for (int i = 0; i < 10; i++)
    {
        rand();
    }
    
    unsigned int *numbers2 = createNumbers(5);
    
    TEST_ASSERT_NOT_NULL(numbers1);
    TEST_ASSERT_NOT_NULL(numbers2);
    
    // It's possible (though unlikely) that two random arrays are identical
    // So we'll just verify that the function works and can produce different results
    // by checking that both have correct structure
    int identical = 1;
    for (unsigned int i = 0; i < 5; i++)
    {
        if (numbers1[i] != numbers2[i])
        {
            identical = 0;
            break;
        }
    }
    
    // Note: identical could be 0 or 1, both are valid test outcomes
    // The important thing is that both arrays are valid
    (void)identical;
    
    free(numbers1);
    free(numbers2);
}

// ============================================================================
// TEST SUITE 8: getDuplicate() - Finding the Duplicate
// ============================================================================

// Test 8.1: getDuplicate finds the correct value for len=5
void test_getDuplicate_FindsCorrectValueLen5(void)
{
    unsigned int *numbers = createNumbers(5);
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Find the duplicate manually (using our test helper)
    unsigned int expectedDuplicate = findDuplicate(numbers, 5);
    TEST_ASSERT_NOT_EQUAL(0, expectedDuplicate);
    
    // Test getDuplicate() - should find the same duplicate
    unsigned int actualDuplicate = getDuplicate(numbers, 5);
    TEST_ASSERT_EQUAL_INT(expectedDuplicate, actualDuplicate);
    
    free(numbers);
}

// Test 8.2: getDuplicate finds the correct value for len=10
void test_getDuplicate_FindsCorrectValueLen10(void)
{
    unsigned int *numbers = createNumbers(10);
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Find the duplicate manually (using our test helper)
    unsigned int expectedDuplicate = findDuplicate(numbers, 10);
    TEST_ASSERT_NOT_EQUAL(0, expectedDuplicate);
    
    // Test getDuplicate() - should find the same duplicate
    unsigned int actualDuplicate = getDuplicate(numbers, 10);
    TEST_ASSERT_EQUAL_INT(expectedDuplicate, actualDuplicate);
    
    free(numbers);
}

// Test 8.3: getDuplicate handles NULL pointer gracefully
void test_getDuplicate_NullPointerReturnsZero(void)
{
    unsigned int result = getDuplicate(NULL, 5);
    TEST_ASSERT_EQUAL_INT(0, result);
}

// Test 8.4: getDuplicate handles len < 2 gracefully
void test_getDuplicate_InvalidLenReturnsZero(void)
{
    unsigned int arr[] = {1};
    
    // len = 0
    unsigned int result0 = getDuplicate(arr, 0);
    TEST_ASSERT_EQUAL_INT(0, result0);
    
    // len = 1
    unsigned int result1 = getDuplicate(arr, 1);
    TEST_ASSERT_EQUAL_INT(0, result1);
}

// Test 8.5: getDuplicate works with len=20
void test_getDuplicate_FindsCorrectValueLen20(void)
{
    unsigned int *numbers = createNumbers(20);
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Find the duplicate using our test helper
    unsigned int expectedDuplicate = findDuplicate(numbers, 20);
    TEST_ASSERT_NOT_EQUAL(0, expectedDuplicate);
    
    // Test getDuplicate()
    unsigned int actualDuplicate = getDuplicate(numbers, 20);
    TEST_ASSERT_EQUAL_INT(expectedDuplicate, actualDuplicate);
    
    free(numbers);
}

// Test 8.6: getDuplicate doesn't modify the input array
void test_getDuplicate_DoesNotModifyInputArray(void)
{
    unsigned int *original = createNumbers(8);
    TEST_ASSERT_NOT_NULL(original);
    
    // Create a copy to compare before and after
    unsigned int *copy = (unsigned int *)malloc(8 * sizeof(unsigned int));
    memcpy(copy, original, 8 * sizeof(unsigned int));
    
    // Call getDuplicate (which creates its own sorted copy internally)
    getDuplicate(original, 8);
    
    // Verify the input array wasn't modified
    for (unsigned int i = 0; i < 8; i++)
    {
        TEST_ASSERT_EQUAL_INT(copy[i], original[i]);
    }
    
    free(original);
    free(copy);
}

// ============================================================================
// TEST SUITE 9: Integration Tests
// ============================================================================

// Test 9.1: Full workflow for len=3
void test_integration_CreateAndValidateLen3(void)
{
    unsigned int *numbers = createNumbers(3);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Validate: 3 elements exist and have valid values
    for (unsigned int i = 0; i < 3; i++)
    {
        TEST_ASSERT_TRUE(numbers[i] > 0);
    }
    
    // Validate: exactly 2 distinct values (one appears twice)
    unsigned int distinct = countDistinctValues(numbers, 3);
    TEST_ASSERT_EQUAL_INT(2, distinct);
    
    free(numbers);
}

// Test 9.2: Full workflow for len=15
void test_integration_CreateAndValidateLen15(void)
{
    unsigned int *numbers = createNumbers(15);
    
    TEST_ASSERT_NOT_NULL(numbers);
    
    // Validate: 15 elements exist and have valid values
    for (unsigned int i = 0; i < 15; i++)
    {
        TEST_ASSERT_TRUE(numbers[i] > 0);
    }
    
    // Validate: exactly 14 distinct values
    unsigned int distinct = countDistinctValues(numbers, 15);
    TEST_ASSERT_EQUAL_INT(14, distinct);
    
    free(numbers);
}

// Test 9.3: Memory cleanup - no segfault
void test_integration_MultipleAllocationsAndFrees(void)
{
    for (unsigned int run = 0; run < 5; run++)
    {
        unsigned int *numbers = createNumbers(5 + run);
        TEST_ASSERT_NOT_NULL(numbers);
        free(numbers);
    }
    
    // If we reach here without segfault, cleanup worked
    TEST_ASSERT_TRUE(1);
}

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

int main(void)
{
    UNITY_BEGIN();
    
    // Initialize random number seed once at the beginning
    srand(time(NULL));
    
    // Test Suite 1: Input Validation
    RUN_TEST(test_createNumbers_InvalidLenZero);
    RUN_TEST(test_createNumbers_InvalidLenOne);
    
    // Test Suite 2: Minimum Valid Input
    RUN_TEST(test_createNumbers_MinimumSize);
    
    // Test Suite 3: Array Size
    RUN_TEST(test_createNumbers_ArraySize5);
    RUN_TEST(test_createNumbers_ArraySize10);
    
    // Test Suite 4: Value Range
    RUN_TEST(test_createNumbers_ValueRangeLen5);
    RUN_TEST(test_createNumbers_ValueRangeLen20);
    
    // Test Suite 5: Duplicate Detection
    RUN_TEST(test_createNumbers_ExactlyOneDuplicateLen5);
    RUN_TEST(test_createNumbers_ExactlyOneDuplicateLen10);
    RUN_TEST(test_createNumbers_NoTriplicatesLen5);
    
    // Test Suite 6: No Accidental Duplicates
    RUN_TEST(test_createNumbers_TotalCountLen5);
    
    // Test Suite 7: Randomness
    RUN_TEST(test_createNumbers_DifferentRandomResults);
    
    // Test Suite 8: getDuplicate
    RUN_TEST(test_getDuplicate_FindsCorrectValueLen5);
    RUN_TEST(test_getDuplicate_FindsCorrectValueLen10);
    RUN_TEST(test_getDuplicate_NullPointerReturnsZero);
    RUN_TEST(test_getDuplicate_InvalidLenReturnsZero);
    RUN_TEST(test_getDuplicate_FindsCorrectValueLen20);
    RUN_TEST(test_getDuplicate_DoesNotModifyInputArray);
    
    // Test Suite 9: Integration
    RUN_TEST(test_integration_CreateAndValidateLen3);
    RUN_TEST(test_integration_CreateAndValidateLen15);
    RUN_TEST(test_integration_MultipleAllocationsAndFrees);
    
    return UNITY_END();
}