#include <windows.h>

#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <intrin.h>

#include "hook/table.h"

#include "hooklib/config.h"

#include "platform/openssl.h"

#include "util/dprintf.h"

/* API hooks */

static char * __cdecl hook_getenv(const char *name);

/* Link pointers */

static char * (__cdecl *next_getenv)(const char *name);

static bool openssl_hook_initted;
static struct openssl_config openssl_config;

static const struct hook_symbol openssl_hooks[] = {
    {
        .name  = "getenv",
        .patch = hook_getenv,
        .link  = (void **) &next_getenv
    },
};

int check_intel_sha_extension() {
    int cpui[4] = {0};

    __cpuid(cpui, 0);
    int nIds_ = cpui[0];

    char vendor[0x20] = {0};
    *((int*)vendor) = cpui[1];
    *((int*)(vendor + 4)) = cpui[3];
    *((int*)(vendor + 8)) = cpui[2];

    // Intel CPU
    int isIntel = (strcmp(vendor, "GenuineIntel") == 0);

    if (isIntel && nIds_ >= 7) {
        __cpuidex(cpui, 7, 0);
        // SHA extension
        return (cpui[1] & (1 << 29)) != 0; 
    }

    return 0;
}

HRESULT openssl_hook_init(const struct openssl_config *cfg)
{
    assert(cfg != NULL);

    if (!cfg->enable) {
        return S_FALSE;
    }

    if (openssl_hook_initted) {
        return S_FALSE;
    }

    if (cfg->override) {
        dprintf("OpenSSL: hook enabled.\n");
    } else if (check_intel_sha_extension()) {
        dprintf("OpenSSL: Intel CPU SHA extension detected, hook enabled.\n");
    } else {
        return S_FALSE;
    }

    openssl_hook_initted = true;

    memcpy(&openssl_config, cfg, sizeof(*cfg));
    hook_table_apply(
        NULL,
        "msvcr110.dll",
        openssl_hooks,
        _countof(openssl_hooks)
    );

    return S_OK;
}

static char * __cdecl hook_getenv(const char *name)
{
    /* Intercept OpenSSL CPU-cap override */
    if (name && strcmp(name, "OPENSSL_ia32cap") == 0) {
        static char override[] = "~0x20000000";

        dprintf("OpenSSL: Overriding OPENSSL_ia32cap -> %s\n", override);
        
        return override;
    }

    char *real_val = next_getenv(name);

    return real_val;
}