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

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

/* Wrapper provided in the module for calling the static function */
extern void test_htmlParseStartTag(htmlParserCtxtPtr ctxt);

/* Simple capture of SAX startElement events */
typedef struct {
    xmlChar *name;
    int att_count;          /* number of attribute pairs */
    xmlChar **atts;         /* flattened name, value, name, value..., NULL terminated */
} StartEvent;

typedef struct {
    int nevents;
    StartEvent events[64];
} SAXCapture;

static void capture_init(SAXCapture *cap) {
    memset(cap, 0, sizeof(*cap));
}

static void capture_free(SAXCapture *cap) {
    for (int i = 0; i < cap->nevents; i++) {
        if (cap->events[i].name) {
            xmlFree(cap->events[i].name);
        }
        if (cap->events[i].atts) {
            /* Free copied attribute names and values */
            int j = 0;
            while (cap->events[i].atts[j] != NULL) {
                xmlFree(cap->events[i].atts[j]);
                j++;
            }
            free(cap->events[i].atts);
        }
    }
    memset(cap, 0, sizeof(*cap));
}

static void test_sax_startElement(void *ctx, const xmlChar *name, const xmlChar **atts) {
    SAXCapture *cap = (SAXCapture *)ctx;
    if (cap->nevents >= (int)(sizeof(cap->events)/sizeof(cap->events[0])))
        return;
    StartEvent *ev = &cap->events[cap->nevents++];
    ev->name = xmlStrdup(name);

    int count = 0;
    if (atts != NULL) {
        const xmlChar **p = atts;
        while (*p != NULL) {
            /* name */
            p++;
            /* value */
            if (*p == NULL) break;
            p++;
            count++;
        }
    }
    ev->att_count = count;

    if (atts != NULL && count > 0) {
        /* allocate space for 2*count + 1 NULL terminator */
        ev->atts = (xmlChar **)calloc((size_t)(2 * count + 1), sizeof(xmlChar *));
        int idx = 0;
        for (int i = 0; i < count; i++) {
            const xmlChar *aname = atts[2*i];
            const xmlChar *aval  = atts[2*i + 1];
            ev->atts[idx++] = xmlStrdup(aname);
            ev->atts[idx++] = (aval != NULL) ? xmlStrdup(aval) : NULL;
        }
        ev->atts[idx] = NULL;
    } else {
        ev->atts = (xmlChar **)calloc(1, sizeof(xmlChar *));
        ev->atts[0] = NULL;
    }
}

static const xmlChar* find_attr_value(const StartEvent *ev, const char *name) {
    if (ev->atts == NULL) return NULL;
    for (int i = 0; ev->atts[i] != NULL && ev->atts[i+1] != NULL; i += 2) {
        if (xmlStrcasecmp(ev->atts[i], (const xmlChar *)name) == 0) {
            return ev->atts[i+1];
        }
    }
    return NULL;
}

/* Create a parser context from a memory buffer and attach our SAX handler */
static htmlParserCtxtPtr make_ctxt(const char *buf, int flags, SAXCapture *cap) {
    htmlParserCtxtPtr ctxt = htmlCreateMemoryParserCtxt(buf, (int)strlen(buf));
    TEST_ASSERT_NOT_NULL_MESSAGE(ctxt, "Failed to create HTML parser context");
    static xmlSAXHandler sax; /* static to ensure it lives long enough */
    memset(&sax, 0, sizeof(sax));
    sax.startElement = test_sax_startElement;
    ctxt->sax = &sax;
    ctxt->userData = cap;
    ctxt->options |= flags;
    return ctxt;
}

void setUp(void) {
    /* Initialize libxml2 for safety */
    xmlInitParser();
}

void tearDown(void) {
    /* No global cleanup here to avoid interfering between tests */
}

/* Test: simple start tag without implied element insertion (NOIMPLIED) */
void test_htmlParseStartTag_simple_div_noimplied(void) {
    const char *src = "<div>";
    SAXCapture cap; capture_init(&cap);
    htmlParserCtxtPtr ctxt = make_ctxt(src, HTML_PARSE_NOIMPLIED, &cap);

    test_htmlParseStartTag(ctxt);

    TEST_ASSERT_EQUAL_INT(1, cap.nevents);
    TEST_ASSERT_NOT_NULL(cap.events[0].name);
    TEST_ASSERT_EQUAL_STRING("div", (const char *)cap.events[0].name);
    TEST_ASSERT_EQUAL_INT(0, cap.events[0].att_count);

    capture_free(&cap);
    htmlFreeParserCtxt(ctxt);
}

/* Test: uppercase tag and attribute names are lowercased; values preserved */
void test_htmlParseStartTag_uppercase_and_attr_lowercased(void) {
    const char *src = "<DIV CLASS=AbC ID=42>";
    SAXCapture cap; capture_init(&cap);
    htmlParserCtxtPtr ctxt = make_ctxt(src, HTML_PARSE_NOIMPLIED, &cap);

    test_htmlParseStartTag(ctxt);

    TEST_ASSERT_EQUAL_INT(1, cap.nevents);
    TEST_ASSERT_EQUAL_STRING("div", (const char *)cap.events[0].name);
    TEST_ASSERT_TRUE(cap.events[0].att_count >= 2);

    /* Attribute names should be lowercased */
    const xmlChar *vclass = find_attr_value(&cap.events[0], "class");
    const xmlChar *vid    = find_attr_value(&cap.events[0], "id");
    TEST_ASSERT_NOT_NULL(vclass);
    TEST_ASSERT_NOT_NULL(vid);
    TEST_ASSERT_EQUAL_STRING("AbC", (const char *)vclass);
    TEST_ASSERT_EQUAL_STRING("42",  (const char *)vid);

    capture_free(&cap);
    htmlFreeParserCtxt(ctxt);
}

/* Test: duplicate attributes are de-duplicated with first value preserved */
void test_htmlParseStartTag_duplicate_attributes_dedup(void) {
    const char *src = "<div class='a' CLASS=\"b\" class=c>";
    SAXCapture cap; capture_init(&cap);
    htmlParserCtxtPtr ctxt = make_ctxt(src, HTML_PARSE_NOIMPLIED, &cap);

    test_htmlParseStartTag(ctxt);

    TEST_ASSERT_EQUAL_INT(1, cap.nevents);
    /* Only one 'class' attribute should remain, with the first value 'a' */
    const StartEvent *ev = &cap.events[0];
    /* Count how many 'class' attributes remain */
    int class_count = 0;
    for (int i = 0; ev->atts[i] != NULL && ev->atts[i+1] != NULL; i += 2) {
        if (xmlStrcasecmp(ev->atts[i], BAD_CAST "class") == 0)
            class_count++;
    }
    TEST_ASSERT_EQUAL_INT(1, class_count);
    const xmlChar *v = find_attr_value(ev, "class");
    TEST_ASSERT_NOT_NULL(v);
    TEST_ASSERT_EQUAL_STRING("a", (const char *)v);

    capture_free(&cap);
    htmlFreeParserCtxt(ctxt);
}

/* Test: unexpected solidus inside tag (not as '/>') is ignored */
void test_htmlParseStartTag_unexpected_solidus_ignored(void) {
    const char *src = "<div / id='x'>";
    SAXCapture cap; capture_init(&cap);
    htmlParserCtxtPtr ctxt = make_ctxt(src, HTML_PARSE_NOIMPLIED, &cap);

    test_htmlParseStartTag(ctxt);

    TEST_ASSERT_EQUAL_INT(1, cap.nevents);
    TEST_ASSERT_EQUAL_STRING("div", (const char *)cap.events[0].name);
    const xmlChar *vx = find_attr_value(&cap.events[0], "id");
    TEST_ASSERT_NOT_NULL(vx);
    TEST_ASSERT_EQUAL_STRING("x", (const char *)vx);

    capture_free(&cap);
    htmlFreeParserCtxt(ctxt);
}

/* Test: self-closing tags '/>' are handled and produce a startElement event */
void test_htmlParseStartTag_self_closing(void) {
    const char *src = "<br/>";
    SAXCapture cap; capture_init(&cap);
    htmlParserCtxtPtr ctxt = make_ctxt(src, HTML_PARSE_NOIMPLIED, &cap);

    test_htmlParseStartTag(ctxt);

    TEST_ASSERT_EQUAL_INT(1, cap.nevents);
    TEST_ASSERT_EQUAL_STRING("br", (const char *)cap.events[0].name);
    TEST_ASSERT_EQUAL_INT(0, cap.events[0].att_count);

    capture_free(&cap);
    htmlFreeParserCtxt(ctxt);
}

/* Test: incomplete tag without closing '>' is discarded (no SAX events) */
void test_htmlParseStartTag_incomplete_tag_discarded(void) {
    const char *src = "<div id='x'";
    SAXCapture cap; capture_init(&cap);
    htmlParserCtxtPtr ctxt = make_ctxt(src, HTML_PARSE_NOIMPLIED, &cap);

    test_htmlParseStartTag(ctxt);

    TEST_ASSERT_EQUAL_INT(0, cap.nevents);

    capture_free(&cap);
    htmlFreeParserCtxt(ctxt);
}

/* Test: many attributes are all passed (exercises attribute storage growth) */
void test_htmlParseStartTag_many_attributes(void) {
    /* Build a tag with many attributes */
    char buf[4096];
    strcpy(buf, "<span");
    const int N = 20;
    char tmp[64];
    for (int i = 0; i < N; i++) {
        snprintf(tmp, sizeof(tmp), " a%d='v%d'", i, i);
        strcat(buf, tmp);
    }
    strcat(buf, ">");

    SAXCapture cap; capture_init(&cap);
    htmlParserCtxtPtr ctxt = make_ctxt(buf, HTML_PARSE_NOIMPLIED, &cap);

    test_htmlParseStartTag(ctxt);

    TEST_ASSERT_EQUAL_INT(1, cap.nevents);
    TEST_ASSERT_EQUAL_STRING("span", (const char *)cap.events[0].name);
    TEST_ASSERT_EQUAL_INT(N, cap.events[0].att_count);

    /* Spot-check a few attributes */
    const StartEvent *ev = &cap.events[0];
    const xmlChar *v0 = find_attr_value(ev, "a0");
    const xmlChar *v7 = find_attr_value(ev, "a7");
    const xmlChar *v19 = find_attr_value(ev, "a19");
    TEST_ASSERT_NOT_NULL(v0);
    TEST_ASSERT_NOT_NULL(v7);
    TEST_ASSERT_NOT_NULL(v19);
    TEST_ASSERT_EQUAL_STRING("v0",  (const char *)v0);
    TEST_ASSERT_EQUAL_STRING("v7",  (const char *)v7);
    TEST_ASSERT_EQUAL_STRING("v19", (const char *)v19);

    capture_free(&cap);
    htmlFreeParserCtxt(ctxt);
}

int main(void) {
    UNITY_BEGIN();

    RUN_TEST(test_htmlParseStartTag_simple_div_noimplied);
    RUN_TEST(test_htmlParseStartTag_uppercase_and_attr_lowercased);
    RUN_TEST(test_htmlParseStartTag_duplicate_attributes_dedup);
    RUN_TEST(test_htmlParseStartTag_unexpected_solidus_ignored);
    RUN_TEST(test_htmlParseStartTag_self_closing);
    RUN_TEST(test_htmlParseStartTag_incomplete_tag_discarded);
    RUN_TEST(test_htmlParseStartTag_many_attributes);

    return UNITY_END();
}