#include "../../unity/unity.h"
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>

/* Helper: free all dynamically allocated outlist nodes and reset head/tail.
   outlist_head and outlist_end are defined in the program under test. */
static void reset_outlist(void)
{
    /* Free all nodes starting from the first real node. */
    struct outlist *p = outlist_head.next;
    while (p)
    {
        struct outlist *n = p->next;
        free(p);
        p = n;
    }
    /* Reset list to initial empty state. */
    outlist_head.next = NULL;
    outlist_end = &outlist_head;
}

/* Subprocess runner to check that invalid inputs are rejected.
   Returns:
     1 if child terminated abnormally (signal) or with non-zero exit.
     0 if child exited normally with status 0 (unexpected).
    On fork/wait errors, this test will assert-fail. */
static int run_child_expect_failure(int file, idx_t field)
{
    fflush(stdout);
    fflush(stderr);
    pid_t pid = fork();
    if (pid < 0)
    {
        TEST_FAIL_MESSAGE("fork failed");
        return 0;
    }

    if (pid == 0)
    {
        /* Child: attempt invalid call. If it returns, exit 0 to signal failure. */
        /* Ensure child's list state is independent due to copy-on-write; no need to cleanup. */
        add_field(file, field);
        _exit(0);
    }

    int status = 0;
    pid_t w = waitpid(pid, &status, 0);
    if (w < 0)
    {
        TEST_FAIL_MESSAGE("waitpid failed");
        return 0;
    }

    if (WIFEXITED(status))
    {
        int code = WEXITSTATUS(status);
        return code != 0; /* success if non-zero exit */
    }
    else if (WIFSIGNALED(status))
    {
        /* Aborted by a signal (e.g., SIGABRT). Treat as success. */
        return 1;
    }
    /* Other cases are unexpected; treat as failure. */
    return 0;
}

void setUp(void)
{
    reset_outlist();
}

void tearDown(void)
{
    reset_outlist();
}

/* Test: adding a single (file=0, field=0) node into empty list. */
static void test_add_field_single_zero_file_zero_field(void)
{
    TEST_ASSERT_NULL(outlist_head.next);
    TEST_ASSERT_EQUAL_PTR(&outlist_head, outlist_end);

    add_field(0, 0);

    TEST_ASSERT_NOT_NULL(outlist_head.next);
    struct outlist *n1 = outlist_head.next;
    TEST_ASSERT_EQUAL_INT(0, n1->file);
    TEST_ASSERT_EQUAL(0, n1->field);
    TEST_ASSERT_NULL(n1->next);

    TEST_ASSERT_EQUAL_PTR(n1, outlist_end);
}

/* Test: appending multiple nodes maintains correct order and content. */
static void test_add_field_multiple_append_order_and_values(void)
{
    add_field(1, 3);
    add_field(2, 4);
    add_field(1, 0);

    struct outlist *n1 = outlist_head.next;
    TEST_ASSERT_NOT_NULL(n1);
    TEST_ASSERT_EQUAL_INT(1, n1->file);
    TEST_ASSERT_EQUAL(3, n1->field);

    struct outlist *n2 = n1->next;
    TEST_ASSERT_NOT_NULL(n2);
    TEST_ASSERT_EQUAL_INT(2, n2->file);
    TEST_ASSERT_EQUAL(4, n2->field);

    struct outlist *n3 = n2->next;
    TEST_ASSERT_NOT_NULL(n3);
    TEST_ASSERT_EQUAL_INT(1, n3->file);
    TEST_ASSERT_EQUAL(0, n3->field);

    TEST_ASSERT_NULL(n3->next);
    TEST_ASSERT_EQUAL_PTR(n3, outlist_end);
}

/* Test: outlist_end updates correctly after each append. */
static void test_add_field_tail_updates_correctly(void)
{
    TEST_ASSERT_EQUAL_PTR(&outlist_head, outlist_end);

    add_field(1, 1);
    struct outlist *n1 = outlist_head.next;
    TEST_ASSERT_EQUAL_PTR(n1, outlist_end);
    TEST_ASSERT_NULL(n1->next);

    add_field(2, 2);
    struct outlist *n2 = n1->next;
    TEST_ASSERT_NOT_NULL(n2);
    TEST_ASSERT_EQUAL_PTR(n2, outlist_end);
    TEST_ASSERT_NULL(n2->next);
    TEST_ASSERT_EQUAL_PTR(n2, outlist_head.next->next);

    add_field(1, 99);
    struct outlist *n3 = n2->next;
    TEST_ASSERT_NOT_NULL(n3);
    TEST_ASSERT_EQUAL_PTR(n3, outlist_end);
    TEST_ASSERT_NULL(n3->next);
    TEST_ASSERT_EQUAL_INT(1, n3->file);
    TEST_ASSERT_EQUAL(99, n3->field);
}

/* Test: large field value is stored as-is. */
static void test_add_field_large_field_value(void)
{
    idx_t big = (idx_t)123456789;
    add_field(2, big);

    struct outlist *n1 = outlist_head.next;
    TEST_ASSERT_NOT_NULL(n1);
    TEST_ASSERT_EQUAL_INT(2, n1->file);
    TEST_ASSERT_EQUAL(big, n1->field);
    TEST_ASSERT_EQUAL_PTR(n1, outlist_end);
}

/* Test: invalid file number should fail (affirm). */
static void test_add_field_invalid_file_number_fails(void)
{
    /* Values not equal to 0,1,2 should trigger failure. */
    int ok_neg = run_child_expect_failure(-1, 0);
    int ok_3 = run_child_expect_failure(3, 0);
    TEST_ASSERT_TRUE(ok_neg);
    TEST_ASSERT_TRUE(ok_3);
}

/* Test: file=0 with non-zero field should fail (affirm). */
static void test_add_field_file_zero_with_nonzero_field_fails(void)
{
    int ok = run_child_expect_failure(0, 1);
    TEST_ASSERT_TRUE(ok);
}

int main(void)
{
    UNITY_BEGIN();

    RUN_TEST(test_add_field_single_zero_file_zero_field);
    RUN_TEST(test_add_field_multiple_append_order_and_values);
    RUN_TEST(test_add_field_tail_updates_correctly);
    RUN_TEST(test_add_field_large_field_value);
    RUN_TEST(test_add_field_invalid_file_number_fails);
    RUN_TEST(test_add_field_file_zero_with_nonzero_field_fails);

    return UNITY_END();
}