// test_numbers_unity.c
#include "unity.h"
#include "numbers.h"

#include <stdlib.h>
#include <string.h>

void setUp(void)   { /* nothing */ }
void tearDown(void){ /* nothing */ }

// Zählt Vorkommen eines Werts im Array
static unsigned count_occurrences(const unsigned int *arr, unsigned int len, unsigned int value)
{
    unsigned cnt = 0;
    for (unsigned i = 0; i < len; ++i)
        if (arr[i] == value) ++cnt;
    return cnt;
}

/* Prüft Eigenschaften von createNumbers:
   - Wertebereich: [1..2*len]
   - Genau EIN Wert doppelt (keiner > 2x)
   Liefert den doppelten Wert per Out-Param zurück.
*/
static void assert_numbers_properties(const unsigned int *arr, unsigned int len, unsigned int *dup_out)
{
    TEST_ASSERT_NOT_NULL(arr);
    TEST_ASSERT_TRUE(len >= 2);

    const unsigned int maxVal = 2 * len;

    // Häufigkeitstabelle von 0..maxVal (0 bleibt ungenutzt)
    unsigned int *counts = (unsigned int*)calloc(maxVal + 1, sizeof(unsigned int));
    TEST_ASSERT_NOT_NULL_MESSAGE(counts, "calloc(counts) failed");

    for (unsigned int i = 0; i < len; ++i)
    {
        unsigned int v = arr[i];
        TEST_ASSERT_TRUE_MESSAGE(v >= 1 && v <= maxVal, "value out of [1..2*len]");
        counts[v]++;
    }

    int dupCount = 0;
    unsigned int dupVal = 0;
    for (unsigned int v = 1; v <= maxVal; ++v)
    {
        if (counts[v] == 2) { dupCount++; dupVal = v; }
        TEST_ASSERT_LESS_OR_EQUAL_UINT_MESSAGE(2u, counts[v], "a value occurs more than twice");
    }

    free(counts);

    TEST_ASSERT_EQUAL_INT_MESSAGE(1, dupCount, "not exactly one duplicated value");
    if (dup_out) *dup_out = dupVal;
}

// Einzeltests 

// createNumbers: len < 2 -> NULL
static void test_createNumbers_len_too_small(void)
{
    TEST_ASSERT_NULL(createNumbers(0));
    TEST_ASSERT_NULL(createNumbers(1));
}

// createNumbers: Eigenschaften bei repräsentativer Länge
static void test_createNumbers_properties_len20(void)
{
    const unsigned int len = 20;
    unsigned int *arr = createNumbers(len);
    TEST_ASSERT_NOT_NULL(arr);

    unsigned int dupVal = 0;
    assert_numbers_properties(arr, len, &dupVal);

    // Der gefundene doppelte Wert muss auch wirklich genau 2x im Array stehen
    TEST_ASSERT_EQUAL_UINT(2u, count_occurrences(arr, len, dupVal));

    free(arr);
}

// getDuplicate: Minimalfall [x, x] -> x
static void test_getDuplicate_minimal_pair(void)
{
    unsigned int a[2] = { 5, 5 };
    TEST_ASSERT_EQUAL_UINT(5u, getDuplicate(a, 2));
}

// getDuplicate: Bekannte, unsortierte Arrays
static void test_getDuplicate_known_arrays(void)
{
    unsigned int a1[] = {1,2,3,4,5,3};          // dup = 3
    unsigned int a2[] = {7,1,3,4,7};            // dup = 7
    unsigned int a3[] = {9,8,9,1,2,3,4};        // dup = 9

    TEST_ASSERT_EQUAL_UINT(3u, getDuplicate(a1, (unsigned) (sizeof a1/sizeof a1[0])));
    TEST_ASSERT_EQUAL_UINT(7u, getDuplicate(a2, (unsigned) (sizeof a2/sizeof a2[0])));
    TEST_ASSERT_EQUAL_UINT(9u, getDuplicate(a3, (unsigned) (sizeof a3/sizeof a3[0])));
}

// getDuplicate: Ungültige Eingaben -> 0
static void test_getDuplicate_invalid_inputs(void)
{
    TEST_ASSERT_EQUAL_UINT(0u, getDuplicate(NULL, 10));
    unsigned int x = 42;
    TEST_ASSERT_EQUAL_UINT(0u, getDuplicate(&x, 1));
}

// Integration: createNumbers + getDuplicate (mehrere Läufe)
static void test_integration_create_then_getDuplicate_multi_runs(void)
{
    const unsigned int len = 30;
    for (int run = 0; run < 3; ++run)
    {
        unsigned int *arr = createNumbers(len);
        TEST_ASSERT_NOT_NULL(arr);

        // Eigenschaften prüfen
        unsigned int dupVal = 0;
        assert_numbers_properties(arr, len, &dupVal);

        // getDuplicate muss genau diesen Wert liefern
        TEST_ASSERT_EQUAL_UINT(dupVal, getDuplicate(arr, len));

        free(arr);
    }
}

// getDuplicate verändert das Original-Array NICHT
static void test_getDuplicate_does_not_modify_input(void)
{
    unsigned int arr[] = { 10, 2, 10, 7, 8, 9, 1 };
    unsigned int original[sizeof arr/sizeof arr[0]];
    memcpy(original, arr, sizeof arr);

    unsigned int dup = getDuplicate(arr, (unsigned) (sizeof arr/sizeof arr[0]));
    TEST_ASSERT_EQUAL_UINT(10u, dup);

    // Speicherinhalt identisch?
    TEST_ASSERT_EQUAL_MEMORY(original, arr, sizeof arr);
}

//Runner

int main(void)
{
    UNITY_BEGIN();

    RUN_TEST(test_createNumbers_len_too_small);
    RUN_TEST(test_createNumbers_properties_len20);
    RUN_TEST(test_getDuplicate_minimal_pair);
    RUN_TEST(test_getDuplicate_known_arrays);
    RUN_TEST(test_getDuplicate_invalid_inputs);
    RUN_TEST(test_integration_create_then_getDuplicate_multi_runs);
    RUN_TEST(test_getDuplicate_does_not_modify_input);

    return UNITY_END();
}