#include "unity/unity.h"
#include <libxml/HTMLparser.h>

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

/* Helper: compare raw output to an expected C string */
static void assert_output_equals(const unsigned char *out, int outlen, const char *expected) {
    size_t exp_len = strlen(expected);
    TEST_ASSERT_EQUAL_INT((int)exp_len, outlen);
    TEST_ASSERT_EQUAL_UINT8_ARRAY(expected, out, exp_len);
}

/* Helper: check if output matches one of two expected strings */
static void assert_output_equals_either(const unsigned char *out, int outlen,
                                        const char *exp1, const char *exp2) {
    size_t len1 = strlen(exp1);
    size_t len2 = strlen(exp2);
    bool match1 = (outlen == (int)len1) && (memcmp(out, exp1, len1) == 0);
    bool match2 = (outlen == (int)len2) && (memcmp(out, exp2, len2) == 0);
    if (!(match1 || match2)) {
        /* Provide informative failure with a printable copy */
        char buf[64];
        int n = outlen < (int)sizeof(buf) - 1 ? outlen : (int)sizeof(buf) - 1;
        memcpy(buf, out, n);
        buf[n] = '\0';
        TEST_FAIL_MESSAGE("Output did not match either expected entity representation");
    }
}

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

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

/* Test: in == NULL triggers initialization: ret == 0, outlen and inlen set to 0 */
void test_htmlUTF8ToHtml_initialization_with_null_in(void) {
    unsigned char outbuf[16] = {0};
    int outLen = (int)sizeof(outbuf);
    int inLen = 123; /* arbitrary non-zero */
    int ret = htmlUTF8ToHtml(outbuf, &outLen, NULL, &inLen);
    TEST_ASSERT_EQUAL_INT(0, ret);
    TEST_ASSERT_EQUAL_INT(0, outLen);
    TEST_ASSERT_EQUAL_INT(0, inLen);
}

/* Test: out == NULL should return an error (<0) without crashing */
void test_htmlUTF8ToHtml_null_out_pointer_returns_error(void) {
    const unsigned char inbuf[] = { 'A' };
    int outLen = 16;
    int inLen = (int)sizeof(inbuf);
    int ret = htmlUTF8ToHtml(NULL, &outLen, inbuf, &inLen);
    TEST_ASSERT_LESS_THAN_INT(0, ret);
}

/* Test: ASCII passthrough */
void test_htmlUTF8ToHtml_ascii_passthrough(void) {
    const unsigned char inbuf[] = "Hello";
    unsigned char outbuf[64];
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)strlen((const char *)inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    TEST_ASSERT_EQUAL_INT(5, ret);
    TEST_ASSERT_EQUAL_INT(5, outLen);
    TEST_ASSERT_EQUAL_INT(5, inLen);

    /* Make a temporary NUL-terminated copy to compare as string */
    unsigned char tmp[64];
    memcpy(tmp, outbuf, outLen);
    tmp[outLen] = '\0';
    TEST_ASSERT_EQUAL_STRING("Hello", (const char *)tmp);
}

/* Test: basic 2-byte UTF-8 -> entity (&copy; or &#169;) */
void test_htmlUTF8ToHtml_two_byte_utf8_to_entity_copy(void) {
    const unsigned char inbuf[] = { 0xC2, 0xA9 }; /* U+00A9 COPYRIGHT SIGN */
    unsigned char outbuf[32] = {0};
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)sizeof(inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    TEST_ASSERT_EQUAL_INT(outLen, ret);
    TEST_ASSERT_EQUAL_INT(2, inLen);
    /* Accept either named or numeric */
    assert_output_equals_either(outbuf, outLen, "&copy;", "&#169;");
}

/* Test: mixed ASCII and 2-byte UTF-8 -> entity sequence */
void test_htmlUTF8ToHtml_mixed_ascii_and_entity(void) {
    const unsigned char inbuf[] = { 'A', 0xC2, 0xA9, 'B' }; /* "A©B" */
    unsigned char outbuf[64] = {0};
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)sizeof(inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    TEST_ASSERT_EQUAL_INT(outLen, ret);
    TEST_ASSERT_EQUAL_INT(4, inLen);
    /* Expect "A&copy;B" or "A&#169;B" */
    const char *exp1 = "A&copy;B";
    const char *exp2 = "A&#169;B";
    assert_output_equals_either(outbuf, outLen, exp1, exp2);
}

/* Test: 4-byte UTF-8 (U+1F600 GRINNING FACE) -> numeric entity */
void test_htmlUTF8ToHtml_four_byte_utf8_to_numeric_entity(void) {
    const unsigned char inbuf[] = { 0xF0, 0x9F, 0x98, 0x80 }; /* U+1F600 */
    unsigned char outbuf[32] = {0};
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)sizeof(inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    TEST_ASSERT_EQUAL_INT(outLen, ret);
    TEST_ASSERT_EQUAL_INT(4, inLen);
    assert_output_equals(outbuf, outLen, "&#128512;");
}

/* Test: incomplete multibyte sequence is not consumed and no error; prior ASCII remains */
void test_htmlUTF8ToHtml_incomplete_multibyte_sequence(void) {
    const unsigned char inbuf[] = { 'A', 0xC2 }; /* 'A' followed by first byte of 2-byte sequence */
    unsigned char outbuf[16] = {0};
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)sizeof(inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    /* Should process 'A' and stop before incomplete sequence */
    TEST_ASSERT_EQUAL_INT(1, ret);
    TEST_ASSERT_EQUAL_INT(1, outLen);
    TEST_ASSERT_EQUAL_INT(1, inLen);
    TEST_ASSERT_EQUAL_HEX8('A', outbuf[0]);
}

/* Test: output buffer too small for entity -> error, nothing consumed */
void test_htmlUTF8ToHtml_outbuf_too_small_for_entity(void) {
    const unsigned char inbuf[] = { 0xC2, 0xA9 }; /* © -> requires 6 bytes (&copy; or &#169;) */
    unsigned char outbuf[5] = {0}; /* deliberately too small */
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)sizeof(inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    TEST_ASSERT_LESS_THAN_INT(0, ret); /* space error */
    TEST_ASSERT_EQUAL_INT(0, outLen);
    TEST_ASSERT_EQUAL_INT(0, inLen);
}

/* Test: out buffer too small mid-ASCII -> error, partial consumption accounted */
void test_htmlUTF8ToHtml_outbuf_too_small_mid_ascii(void) {
    const unsigned char inbuf[] = { 'A', 'B', 'C' };
    unsigned char outbuf[2] = {0};
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)sizeof(inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    TEST_ASSERT_LESS_THAN_INT(0, ret); /* space error */
    TEST_ASSERT_EQUAL_INT(2, outLen);
    TEST_ASSERT_EQUAL_INT(2, inLen);
    TEST_ASSERT_EQUAL_HEX8('A', outbuf[0]);
    TEST_ASSERT_EQUAL_HEX8('B', outbuf[1]);
}

/* Test: exact buffer boundary for entity succeeds */
void test_htmlUTF8ToHtml_exact_boundary_for_entity(void) {
    const unsigned char inbuf[] = { 0xC2, 0xA9 }; /* © */
    unsigned char outbuf[6] = {0}; /* exactly enough for &copy; or &#169; */
    int outLen = (int)sizeof(outbuf);
    int inLen = (int)sizeof(inbuf);

    int ret = htmlUTF8ToHtml(outbuf, &outLen, inbuf, &inLen);

    TEST_ASSERT_EQUAL_INT(6, ret);
    TEST_ASSERT_EQUAL_INT(6, outLen);
    TEST_ASSERT_EQUAL_INT(2, inLen);
    assert_output_equals_either(outbuf, outLen, "&copy;", "&#169;");
}

int main(void) {
    UNITY_BEGIN();
    RUN_TEST(test_htmlUTF8ToHtml_initialization_with_null_in);
    RUN_TEST(test_htmlUTF8ToHtml_null_out_pointer_returns_error);
    RUN_TEST(test_htmlUTF8ToHtml_ascii_passthrough);
    RUN_TEST(test_htmlUTF8ToHtml_two_byte_utf8_to_entity_copy);
    RUN_TEST(test_htmlUTF8ToHtml_mixed_ascii_and_entity);
    RUN_TEST(test_htmlUTF8ToHtml_four_byte_utf8_to_numeric_entity);
    RUN_TEST(test_htmlUTF8ToHtml_incomplete_multibyte_sequence);
    RUN_TEST(test_htmlUTF8ToHtml_outbuf_too_small_for_entity);
    RUN_TEST(test_htmlUTF8ToHtml_outbuf_too_small_mid_ascii);
    RUN_TEST(test_htmlUTF8ToHtml_exact_boundary_for_entity);
    return UNITY_END();
}