/*
   Copyright (c)  2014 IOnU Security Inc. All rights reserved
   Created April 2014 by Kendrick Webster

   K2Client/util.c - implementation of util.h
*/
#ifdef WIN32
#include <Windows.h>
#endif
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>
#include <errno.h>
#include <pthread.h>
#ifdef __MACH__
#include <mach/mach_time.h>
#else
#include <time.h>
#endif
#include "eyeinterface.h"
#include "util.h"
#include "eyeconstants.h"

#ifndef WIN32
#pragma GCC diagnostic ignored "-Wunused-function"
#ifdef __MACH__
#include <sys/syslimits.h>
#define MAX_PATH PATH_MAX
#else
#define MAX_PATH 128
#endif
#endif

/* =============================== Logging ============================== */
static log_level_t log_filter_level = LOG_VERBOSE;
static int is_log_open = 0;
static int is_log_level_set = 0;
static int is_config_json_parsed = 0;

static void expand_log_file_path(const char* name, char* path_and_name, size_t path_and_name_size)
{
#ifdef WIN32
    char tmpPathBuf[MAX_PATH + 1] = {0};
    ::GetTempPath(MAX_PATH, reinterpret_cast<LPSTR>(&tmpPathBuf));
    snprintf(path_and_name, path_and_name_size, "%s%s", tmpPathBuf, name);
    path_and_name[path_and_name_size - 1] = 0;
#else // not WIN32
    snprintf(path_and_name, path_and_name_size, "%s%s", LOG_FILE_PATH, name);
#endif // not WIN32
}

static void open_log_file(void)
{
    char log_file[MAX_PATH + 1];
    expand_log_file_path(LOG_FILE_NAME, log_file, sizeof(log_file));
/* TEB 1.2.7 12/11/2014 - log to CONSOLE because only one log config is supported via these api's
    ionu_configfilelog(LOG_SHORT_IDENTIFIER, "", IONU_VERBOSE, log_file);
*/
	ionu_configlog(LOG_SHORT_IDENTIFIER, SL_EYE_TYPE, IONU_VERBOSE, IONU_CONSOLE);

    is_log_open = 1;
}

static void parse_sl_config_json(void);

void initialize_logging(void)
{
    if (!(is_log_level_set || is_config_json_parsed))
    {
        parse_sl_config_json();
    }
#if DEBUG
#else // not DEBUG
    open_log_file();
#endif // not DEBUG
}

void finalize_logging(void)
{
#if DEBUG
#else // not DEBUG
    ionu_closelog();
    is_log_open = 0;
#endif // not DEBUG
}

void set_log_level(log_level_t level)
{
    log_filter_level = level;
    is_log_level_set = 1;
}

static void log_message(log_level_t lev, const char* msg)
{
#if DEBUG
#else // not DEBUG
    if (is_log_open)
    {
        switch (lev)
        {
        case LOG_FATAL:         ionu_log(IONU_FATAL,   msg); break;
        case LOG_ERROR:         ionu_log(IONU_ERROR,   msg); break;
        case LOG_WARNING:       ionu_log(IONU_WARN,    msg); break;
        case LOG_INFORMATIONAL: ionu_log(IONU_INFO,    msg); break;
        case LOG_DEBUG:         ionu_log(IONU_DEBUG,   msg); break;
        case LOG_VERBOSE:       ionu_log(IONU_VERBOSE, msg); break;
        }
    }
#endif // not DEBUG
    if (!is_log_open) // handles DEBUG, also handles messages generated at startup before opening log (i.e. parsing config json)
    {
        switch (lev)
        {
        case LOG_FATAL:         printf("K2 fatal:   %s\n", msg); break;
        case LOG_ERROR:         printf("K2 error:   %s\n", msg); break;
        case LOG_WARNING:       printf("K2 warn:    %s\n", msg); break;
        case LOG_INFORMATIONAL: printf("K2 info:    %s\n", msg); break;
        case LOG_DEBUG:         printf("K2 debug:   %s\n", msg); break;
        case LOG_VERBOSE:       printf("K2 verbose: %s\n", msg); break;
        }
    }
}

static void log_printf_va(log_level_t lev, const char* fmt, va_list marker)
{
	char buf[256];
    vsnprintf(buf, sizeof(buf), fmt, marker);
#ifdef WIN32
    buf[sizeof(buf) - 1] = 0;
#endif
    log_message(lev, buf);
}

void log_printf(log_level_t lev, const char* fmt, ...)
{
	va_list marker;
	va_start(marker, fmt);
    if (lev <= log_filter_level)
    {
        log_printf_va(lev, fmt, marker);
    }
	va_end(marker);
}



/* ==================== configuration settings for logging verbosity ==================== */

/*
    parse_sl_config_json() and helpers

    Parses /sequencelogic/config/{env}.conf.json to extract logging verbosity.

    This is not a full json parser.  It looks for a specific 2nd-level object containing
    a specific item while ignoring all other objects.

    Example json format:

    // comments
    {
        "other": {
           "dontCare": "some value"
        },
        "K2Client": {
            "dontCare": "some value",
            "logLevel": "informational",    // this is the only thing parsed
            "dontCare2": "some value"
        },
        "other2": {
            "dontCare2":
            [
                {
                    "dontCare3": "some value"
                },
                "dontCare4",
                "dontCare5"
            ]
        }
    }

    Example to cut-and-pase into a config file:
    "K2Client": {
        "logLevel": "debug" // choices: fatal, error, warning, informational, debug, verbose
    },
*/
#define JSON_STRING_BUFSIZE 16 // sufficient for "K2Client", "logLevel", and "informational"
static struct
{
    char fname[256];
    FILE *f;
    char c;
    int line;
    int column;
    int depth;
    char s[JSON_STRING_BUFSIZE];
    int is_error;
    int is_this_k2cli;
    int is_this_loglevel;
    int parent_k2cli_depth;
}
json_state;

// advances char pos (including line and column numbers)
static void json_next(void)
{
    int c;
    if (json_state.c)
    {
        c = fgetc(json_state.f);
        c = (EOF == c) ? 0 : c;
        json_state.c = (char)c;
        switch (json_state.c)
        {
        case '\r':
            json_state.column = 0;
            break;

        case '\n':
            json_state.column = 0;
            json_state.line++;
            break;

        default:
            json_state.column++;
            break;
        }
    }
}

// compares c to current char,
//    returns 1 and advances char pos if matched
//    returns 0 and logs error if mismatched
static int json_check(char c)
{
    if (!json_state.is_error)
    {
        if (json_state.c != c)
        {
            log_error("Expected '%c', found '%c' at line %d char %d of %s", c, json_state.c,
                json_state.line, json_state.column, json_state.fname);
            json_state.c = 0;
            json_state.is_error = 1;
            return 0;
        }
        else
        {
            json_next();
            return 1;
        }
    }
    return 0;
}

// alias, used to report errors
#define json_expected json_check

// compares string, returns 1 if matched
static int json_check_str(const char* s)
{
    char c = *s++;
    while (c)
    {
        if (!json_check(c))
        {
            return 0;
        }
        c = *s++;
    }
    return 1;
}

static void json_comment(void)
{
    json_check('/');
    json_check('/');
    while (json_state.c)
    {
        switch (json_state.c)
        {
        case '\r':
        case '\n':
            return;

        default:
            json_next();
            break;
        }
    }
}

static void json_white(void)
{
    while (json_state.c)
    {
        switch (json_state.c)
        {
        case ' ':
        case '\r':
        case '\n':
        case '\t':
            json_next();
            break;

        case '/':
            json_comment();
            break;

        default:
            return;
        }
    }
}

static int is_string(const char* s) // case insensitive
{
    const char *p = json_state.s;
    while (*s)
    {
        if (toupper(*s++) != toupper(*p++))
        {
            return 0;
        }
    }
    return *p ? 0 : 1;
}

static void on_json_loglevel(void)
{
#if DEBUG
    log_info("/sequencelogic/config json logLevel = \"%s\" at line %d char %d of %s", json_state.s, json_state.line, json_state.column, json_state.fname);
#endif
    if (is_string("FATAL"))
    {
        log_filter_level = LOG_FATAL;
    }
    else if (is_string("ERROR"))
    {
        log_filter_level = LOG_ERROR;
    }
    else if (is_string("WARNING"))
    {
        log_filter_level = LOG_WARNING;
    }
    else if (is_string("INFORMATIONAL"))
    {
        log_filter_level = LOG_INFORMATIONAL;
    }
    else if (is_string("DEBUG"))
    {
        log_filter_level = LOG_DEBUG;
    }
    else if (is_string("VERBOSE"))
    {
        log_filter_level = LOG_VERBOSE;
    }
    else
    {
        log_error("logLevel \"%s\" not recognized, choices: fatal, error, warning, informational, debug, verbose", json_state.s);
    }
}

static void on_json_string(void)
{
    if (json_state.is_this_loglevel && (1 == json_state.parent_k2cli_depth) && (2 == json_state.depth))
    {
        on_json_loglevel();
    }
    json_state.is_this_k2cli = is_string("K2CLIENT");
    json_state.is_this_loglevel = is_string("LOGLEVEL");
}

static char hex_to_bin(char c)
{
    return (c <= '9') ? (c - '0') : ((c <= 'F') ? (10 + c - 'A') : (10 + c - 'a'));
}

static char json_string_u_escape(void)
{
    int i = 4;
    char c = 0;
    do
    {
        json_next();
        if (isxdigit(json_state.c))
        {
            c <<= 4;
            c |= hex_to_bin(json_state.c);
        }
        else
        {
            json_expected('0');
            return 0;
        }
    }
    while (--i);
    return c;
}

static void json_string(void)
{
    char *p = json_state.s;
    json_check('"');
    while (json_state.c)
    {
        switch (json_state.c)
        {
        default:
        put_c:
            if (p < (json_state.s + JSON_STRING_BUFSIZE - 1))
            {
                *p++ = json_state.c;
            }
            break;

        case '"':
            *p = 0;
            json_next();
            on_json_string();
            return;

        case '\\':
            json_next();
            switch (json_state.c)
            {
            case '"': goto put_c;
            case '\\': goto put_c;
            case '/': goto put_c;
            case 'b': json_state.c = '\b'; goto put_c;
            case 'f': json_state.c = '\f'; goto put_c;
            case 'n': json_state.c = '\n'; goto put_c;
            case 'r': json_state.c = '\r'; goto put_c;
            case 't': json_state.c = '\t'; goto put_c;
            case 'u': json_state.c = json_string_u_escape(); goto put_c;
            default:
                json_expected('n');
                return;
            }
            break;
        }
        json_next();
    }
}

static void json_value(void);

static void json_object(void)
{
    json_state.parent_k2cli_depth = json_state.parent_k2cli_depth ? (json_state.parent_k2cli_depth + 1) : json_state.is_this_k2cli;
    json_state.depth++;
    json_check('{');
    json_white();
    while (json_state.c)
    {
        if ('}' == json_state.c)
        {
            json_next();
            json_state.parent_k2cli_depth = json_state.parent_k2cli_depth ? (json_state.parent_k2cli_depth - 1) : 0;
            json_state.depth--;
            return;
        }
    next_pair:
        json_string();
        json_white();
        json_check(':');
        json_white();
        json_value();
        json_white();
        switch (json_state.c)
        {
        case ',':
            json_next();
            json_white();
            goto next_pair;

        case '}':
            break;

        default:
            json_expected('}');
            return;
        }
    }
    json_expected('}');
}

static void json_array(void)
{
    json_check('[');
    json_white();
    while (json_state.c)
    {
        if (']' == json_state.c)
        {
            json_next();
            return;
        }
    next_value:
        json_value();
        json_white();
        switch (json_state.c)
        {
        case ',':
            json_next();
            json_white();
            goto next_value;

        case ']':
            break;

        default:
            json_expected(']');
            return;
        }
    }
    json_expected(']');
}

static int json_one_or_more_digits(void)
{
    if (!isdigit(json_state.c))
    {
        json_expected('0');
        return 0;
    }
    do
    {
        json_next();
    }
    while (isdigit(json_state.c));
    return 1;
}

static void json_number(void)
{
    if ('-' == json_state.c)
    {
        json_next();
    }

    if ('0' == json_state.c)
    {
        json_next();
    }
    else if (!json_one_or_more_digits())
    {
        return;
    }

    if ('.' == json_state.c)
    {
        json_next();
        if (!json_one_or_more_digits())
        {
            return;
        }
    }

    if ('E' == toupper(json_state.c))
    {
        json_next();
        if ('+' == json_state.c)
        {
            json_next();
        }
        else if ('-' == json_state.c)
        {
            json_next();
        }
        json_one_or_more_digits();
    }
}

static void json_value(void)
{
    if (isdigit(json_state.c))
    {
        json_number();
    }
    else
    {
        switch (json_state.c)
        {
        case '"': json_string(); break;
        case '-': json_number(); break;
        case '{': json_object(); break;
        case '[': json_array(); break;
        case 't': json_check_str("true"); break;
        case 'f': json_check_str("false"); break;
        case 'n': json_check_str("null"); break;
        default:
            json_expected('0');
            break;
        }
    }
}

static FILE* open_sequencelogic_config_file(void)
{
    FILE *f;
    const char *sequencelogicname = getenv(SL_NAME_ENVIRONMENT_KEY);
    if (NULL == sequencelogicname)
    {
        log_info("%s not found in environment", SL_NAME_ENVIRONMENT_KEY);
        log_info("Unable to find and read the SL configuration json file");
        log_info("Log verbosity thus remains at the hard-coded default");
        return NULL;
    }
#ifdef WIN32
    _snprintf(json_state.fname, sizeof(json_state.fname), "%s%s%s", CONFIG_JSON_PATH_PREFIX, sequencelogicname, CONFIG_JSON_SUFFIX);
    json_state.fname[sizeof(json_state.fname) - 1] = 0;
#else
    snprintf(json_state.fname, sizeof(json_state.fname), "%s%s%s", CONFIG_JSON_PATH_PREFIX, sequencelogicname, CONFIG_JSON_SUFFIX);
#endif
    f = fopen(json_state.fname, "r");
    if (NULL == f)
    {
        log_info("Unable to open configuration file \"%s\":", json_state.fname);
        log_info("%s", strerror(errno));
        log_info("Log verbosity thus remains at the hard-coded default");
    }
    return f;
}

static void parse_sl_config_json(void)
{
    is_config_json_parsed = 1;
    json_state.f = open_sequencelogic_config_file();
    if (NULL == json_state.f)
    {
        return;
    }
    json_state.line = 1;
    json_state.column = 0;
    json_state.depth = 0;
    json_state.is_error = 0;
    json_state.is_this_k2cli = 0;
    json_state.is_this_loglevel = 0;
    json_state.parent_k2cli_depth = 0;
    json_state.c = 1;
    json_next();
    json_white();

    while (json_state.c)
    {
        switch (json_state.c)
        {
        case '{':
            json_object();
            json_white();
            break;

        default:
            json_expected('{');  // expecting a top-level object for sequencelogic config json
            fclose(json_state.f);
            return;
        }
    }
    fclose(json_state.f);
}



/* =============================== 'Random' number source =============================== */

static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
#define LOCK_MUTEX pthread_mutex_lock(&mutex);
#define UNLOCK_MUTEX pthread_mutex_unlock(&mutex);
static sc_hash_state_t rng_entropy_pool; /* random number generator entropy pool */

/* hash an entropy source (high-resolution clock, etc.) into the pool */
void seed_random(void)
{
#define RNG_ADD_HASH(t) do {LOCK_MUTEX sc_hash_vector(&rng_entropy_pool, (uint8_t*)&t, sizeof(t)); UNLOCK_MUTEX} while(0)
#ifdef __MACH__
    uint64_t t = mach_absolute_time();
    RNG_ADD_HASH(t);
#else
#ifdef WIN32
    LARGE_INTEGER t;
    QueryPerformanceCounter(&t);
    RNG_ADD_HASH(t);
#else
    struct timespec t;
    clock_gettime(CLOCK_MONOTONIC, &t);
    RNG_ADD_HASH(t);
    clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &t);
    RNG_ADD_HASH(t);
#endif
#endif
}

/* hash a buffer into the RNG entropy pool */
void seed_random_with_bytes(void* buf, size_t len)
{
    LOCK_MUTEX
    {
        sc_hash_vector(&rng_entropy_pool, buf, len);
    }
    UNLOCK_MUTEX
}

/* returns a random number between 0 and (modulus - 1) */
unsigned int get_random(unsigned int modulus)
{
    unsigned int r = 0;
    if (modulus > 0)
    {
        LOCK_MUTEX
        {
            sc_get_vector(&rng_entropy_pool, &r, sizeof(r));
        }
        UNLOCK_MUTEX
        /*
           The modulo operation below introduces a small bias, but it
           is insignificant for this application (modulus almost always
           below 100, bias only affects server load balancing).
        */
        r %= modulus;
    }
    return r;
}

/* fills <len> bytes of <buf> with randomness */
void get_random_bytes(void* buf, size_t len)
{
    LOCK_MUTEX
    {
        sc_get_vector(&rng_entropy_pool, buf, len);
    }
    UNLOCK_MUTEX
}


/* =============================== Misc ============================== */

/* returns TRUE if string was truncated */
int safe_strcpy(char* d, unsigned int n, const char* s)
{
    if (0 < n)
    {
        while (n--)
        {
            if (0 == (*(d++) = *(s++)))
            {
                return FALSE;
            }
        }
        *(--d) = 0;
    }
    return TRUE;
}