#include "unity/unity.h"
#include "zlib.h"

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

/* Declare the target function with a compatible prototype.
   We use void* for the state parameter to avoid depending on internal headers. */
extern void gz_error(void *state, int err, const char *msg);

static void remove_if_exists(const char *path) {
    if (path) {
        remove(path);
    }
}

void setUp(void) {
    /* Setup code here, or leave empty */
}

void tearDown(void) {
    /* Cleanup code here, or leave empty */
}

static gzFile open_temp_gz(const char *path, const char *mode) {
    remove_if_exists(path);
    gzFile f = gzopen(path, mode);
    TEST_ASSERT_MESSAGE(f != NULL, "gzopen failed to create/open temporary gzip file");
    return f;
}

static void close_and_cleanup(gzFile f, const char *path) {
    if (f) {
        int rc = gzclose(f);
        TEST_ASSERT_MESSAGE(rc == Z_OK, "gzclose failed");
    }
    remove_if_exists(path);
}

/* Test: gz_error with (Z_OK, NULL) clears error and leaves empty message. */
void test_gz_error_clears_with_null_message(void) {
    const char *path = "tmp_gzlib_gz_error_clear.gz";
    gzFile f = open_temp_gz(path, "wb");

    /* Ensure we start clean */
    int errnum = 777;
    const char *msg = gzerror(f, &errnum);
    TEST_ASSERT_EQUAL_INT(Z_OK, errnum);
    TEST_ASSERT_NOT_NULL(msg);

    /* Explicitly clear with Z_OK and NULL message */
    gz_error((void*)f, Z_OK, NULL);

    errnum = 777;
    msg = gzerror(f, &errnum);
    TEST_ASSERT_EQUAL_INT(Z_OK, errnum);
    /* When no message is set, gzerror returns an empty string */
    TEST_ASSERT_NOT_NULL(msg);
    TEST_ASSERT_EQUAL_UINT32(0, (unsigned)strlen(msg));

    close_and_cleanup(f, path);
}

/* Test: gz_error sets error code and allocates message "path: msg". */
void test_gz_error_sets_message_with_path_prefix(void) {
    const char *path = "tmp_gzlib_gz_error_basic.gz";
    gzFile f = open_temp_gz(path, "wb");

    const char *user_msg = "whoops";
    gz_error((void*)f, Z_STREAM_ERROR, user_msg);

    int errnum = 0;
    const char *ret = gzerror(f, &errnum);
    TEST_ASSERT_EQUAL_INT(Z_STREAM_ERROR, errnum);
    TEST_ASSERT_NOT_NULL(ret);

    char expected[512];
#if !defined(NO_snprintf) && !defined(NO_vsnprintf)
    (void)snprintf(expected, sizeof(expected), "%s: %s", path, user_msg);
#else
    strcpy(expected, path);
    strcat(expected, ": ");
    strcat(expected, user_msg);
#endif
    TEST_ASSERT_EQUAL_STRING(expected, ret);

    close_and_cleanup(f, path);
}

/* Test: Calling gz_error repeatedly replaces the previous message and updates the code. */
void test_gz_error_replaces_previous_message(void) {
    const char *path = "tmp_gzlib_gz_error_replace.gz";
    gzFile f = open_temp_gz(path, "wb");

    gz_error((void*)f, Z_DATA_ERROR, "first");
    int err1 = 0;
    const char *msg1 = gzerror(f, &err1);
    TEST_ASSERT_EQUAL_INT(Z_DATA_ERROR, err1);
    TEST_ASSERT_NOT_NULL(msg1);

    gz_error((void*)f, Z_BUF_ERROR, "second");
    int err2 = 0;
    const char *msg2 = gzerror(f, &err2);
    TEST_ASSERT_EQUAL_INT(Z_BUF_ERROR, err2);
    TEST_ASSERT_NOT_NULL(msg2);

    /* Pointer should change because a new allocation occurs for the new message */
    TEST_ASSERT_NOT_EQUAL(msg1, msg2);

    char expected[512];
#if !defined(NO_snprintf) && !defined(NO_vsnprintf)
    (void)snprintf(expected, sizeof(expected), "%s: %s", path, "second");
#else
    strcpy(expected, path);
    strcat(expected, ": ");
    strcat(expected, "second");
#endif
    TEST_ASSERT_EQUAL_STRING(expected, msg2);

    close_and_cleanup(f, path);
}

/* Test: Z_MEM_ERROR returns the literal "out of memory" and does not allocate a message. */
void test_gz_error_mem_error_returns_literal(void) {
    const char *path = "tmp_gzlib_gz_error_mem.gz";
    gzFile f = open_temp_gz(path, "wb");

    /* Trigger a memory error; the message argument should be ignored for allocation. */
    gz_error((void*)f, Z_MEM_ERROR, "ignored");
    int err = 0;
    const char *ret = gzerror(f, &err);
    TEST_ASSERT_EQUAL_INT(Z_MEM_ERROR, err);
    TEST_ASSERT_NOT_NULL(ret);
    TEST_ASSERT_EQUAL_STRING("out of memory", ret);

    /* After a mem error, subsequent errors should still work and set a message */
    gz_error((void*)f, Z_STREAM_ERROR, "later");
    err = 0;
    ret = gzerror(f, &err);
    TEST_ASSERT_EQUAL_INT(Z_STREAM_ERROR, err);

    char expected[512];
#if !defined(NO_snprintf) && !defined(NO_vsnprintf)
    (void)snprintf(expected, sizeof(expected), "%s: %s", path, "later");
#else
    strcpy(expected, path);
    strcat(expected, ": ");
    strcat(expected, "later");
#endif
    TEST_ASSERT_EQUAL_STRING(expected, ret);

    close_and_cleanup(f, path);
}

/* Test: Z_OK with a non-NULL message stores a message while err stays Z_OK. */
void test_gz_error_ok_with_message_stores_message(void) {
    const char *path = "tmp_gzlib_gz_error_okmsg.gz";
    gzFile f = open_temp_gz(path, "wb");

    gz_error((void*)f, Z_OK, "note");
    int err = 0;
    const char *ret = gzerror(f, &err);
    TEST_ASSERT_EQUAL_INT(Z_OK, err);
    TEST_ASSERT_NOT_NULL(ret);

    char expected[512];
#if !defined(NO_snprintf) && !defined(NO_vsnprintf)
    (void)snprintf(expected, sizeof(expected), "%s: %s", path, "note");
#else
    strcpy(expected, path);
    strcat(expected, ": ");
    strcat(expected, "note");
#endif
    TEST_ASSERT_EQUAL_STRING(expected, ret);

    close_and_cleanup(f, path);
}

int main(void) {
    UNITY_BEGIN();
    RUN_TEST(test_gz_error_clears_with_null_message);
    RUN_TEST(test_gz_error_sets_message_with_path_prefix);
    RUN_TEST(test_gz_error_replaces_previous_message);
    RUN_TEST(test_gz_error_mem_error_returns_literal);
    RUN_TEST(test_gz_error_ok_with_message_stores_message);
    return UNITY_END();
}