/* Test that valid POSIX timezone strings are correctly parsed by tzset(3). */
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

// BEGIN test vectors
#include <time.h>
#include <limits.h>

#define IN_SECONDS(h, m, s) ((int32_t) (h) * 3600 + (m) * 60 + (s))
#define NO_TIME INT_MIN

struct tz_test {
    const char* tzstr;
    int32_t offset_seconds;
    int32_t dst_offset_seconds;
};

extern const struct tm winter_tm;
extern const struct tm summer_tm;
extern const time_t winter_time;
extern const time_t summer_time;
extern const struct tz_test test_timezones[];

// winter time is March, 21st 2022 at 8:15pm and 20 seconds
const struct tm winter_tm = {
    .tm_sec     = 20,
    .tm_min     = 15,
    .tm_hour    = 20,
    .tm_mday    = 21,
    .tm_mon     = 3 - 1,
    .tm_year    = 2022 - 1900,
    .tm_isdst   = 0
};

// summer time is July, 15th 2022 at 10:50am and 40 seconds
const struct tm summer_tm = {
    .tm_sec     = 40,
    .tm_min     = 50,
    .tm_hour    = 10,
    .tm_mday    = 15,
    .tm_mon     = 7 - 1,
    .tm_year    = 2022 - 1900,
    .tm_isdst   = 1
};

// UTC unix time for the winter time
const time_t winter_time = 1647893720;
const time_t summer_time = 1657882240;

const struct tz_test test_timezones[] = {
    /*
     * creating test vectors based on the POSIX spec (https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03)
     */
    // normal std names
    {"MAR1",         IN_SECONDS(1, 0, 0),    NO_TIME},
    {"MAR-1",       -IN_SECONDS(1, 0, 0),    NO_TIME},
    {"MAR+2",        IN_SECONDS(2, 0, 0),    NO_TIME},
    {"MAR7",         IN_SECONDS(7, 0, 0),    NO_TIME},
    {"MAR-7",       -IN_SECONDS(7, 0, 0),    NO_TIME},
    {"MARS5",        IN_SECONDS(5, 0, 0),    NO_TIME},
    {"MARSM5",       IN_SECONDS(5, 0, 0),    NO_TIME},
    {"MARSMOON5",    IN_SECONDS(5, 0, 0),    NO_TIME},   // assuming TZNAME_MAX >= 8
    {"MARS5:23:42",  IN_SECONDS(5, 23, 42),  NO_TIME},
    {"SUN-7:14:24", -IN_SECONDS(7, 14, 24),  NO_TIME},
    // with DST
    {"MAR5SMAR",                IN_SECONDS(5, 0, 0), IN_SECONDS(4, 0, 0)},  // only DST name
    {"MAR5SMAR2",               IN_SECONDS(5, 0, 0), IN_SECONDS(2, 0, 0)},  // DST name with offset
    {"MAR3SMAR-3",              IN_SECONDS(3, 0, 0), -IN_SECONDS(3, 0, 0)},
    {"MARSWINTER4MARSUMMER",    IN_SECONDS(4, 0, 0), IN_SECONDS(3, 0, 0)},
    {"MARSWINTER4MARSUMMER3",   IN_SECONDS(4, 0, 0), IN_SECONDS(3, 0, 0)},
    // with DST IN_SECONDSs
    {"WMARS3SMARS,J80",                                 IN_SECONDS(3, 0, 0), IN_SECONDS(2, 0, 0)},
    {"WMARS3SMARS,J80,J134",                            IN_SECONDS(3, 0, 0), IN_SECONDS(2, 0, 0)},
    {"WMARS3SMARS,79",                                  IN_SECONDS(3, 0, 0), IN_SECONDS(2, 0, 0)},
    {"WMARS3SMARS,76,134",                              IN_SECONDS(3, 0, 0), IN_SECONDS(2, 0, 0)},
    {"WMARS3SMARS,76/02,134/03",                        IN_SECONDS(3, 0, 0), IN_SECONDS(2, 0, 0)},
    {"WMARS3SMARS,76/02:15:45,134/03:40:20",            IN_SECONDS(3, 0, 0), IN_SECONDS(2, 0, 0)},
    {"WMARS3SMARS,M3.4.1/02:15:45,M8.3.1/03:40:20",     IN_SECONDS(3, 0, 0), IN_SECONDS(2, 0, 0)},

    // special std names
    {"<UNK>-1",                                 -IN_SECONDS(1, 0, 0),     NO_TIME},
    {"<UNKNOWN>-2",                             -IN_SECONDS(2, 0, 0),     NO_TIME},                  // require TZNAME_MAX >= 7 + 1
    {"<003>3",                                   IN_SECONDS(3, 0, 0),     NO_TIME},
    {"<+04>4",                                   IN_SECONDS(4, 0, 0),     NO_TIME},
    {"<-05>-5",                                 -IN_SECONDS(5, 0, 0),     NO_TIME},
    {"<A-5>6",                                   IN_SECONDS(6, 0, 0),     NO_TIME},
    {"<+A5>-7",                                 -IN_SECONDS(7, 0, 0),     NO_TIME},
    {"<0123456>8",                               IN_SECONDS(8, 0, 0),     NO_TIME},
    {"<0A1B2C3>9",                               IN_SECONDS(9, 0, 0),     NO_TIME},
    {"<RD-04>-4<RD+005>5",                      -IN_SECONDS(4, 0, 0),     IN_SECONDS(5, 0, 0)},
    {"<WINT+03>3<SUM+02>",                       IN_SECONDS(3, 0, 0),     IN_SECONDS(2, 0, 0)},
    {"<WINT+03>3<SUM+02>2",                      IN_SECONDS(3, 0, 0),     IN_SECONDS(2, 0, 0)},
    {"<WINT+03>3:15<SUM+02>2:30:15",             IN_SECONDS(3, 15, 0),    IN_SECONDS(2, 30, 15)},
    {"<H3M15>3:15<H2M30S15>2:30:15",             IN_SECONDS(3, 15, 0),    IN_SECONDS(2, 30, 15)},   // requires TZNAME_MAX >= 8 + 1
    {"<+H6M20S12>6:20:12<-H4M40S14>-4:40:14",    IN_SECONDS(6, 20, 12),  -IN_SECONDS(4, 40, 14)},   // requires TZNAME_MAX >= 9 + 1

    /* 
     * real-world test vectors.
     * IN_SECONDSzones extracted from the tzdb (https://github.com/eggert/tz#2019e).
     * The IN_SECONDSzone strings can also be obtained from https://raw.githubusercontent.com/nayarsystems/posix_tz_db/master/zones.csv.
     */
    { /* Etc/GMT-14 */              "<+14>-14",                        -IN_SECONDS(14, 0, 0),     NO_TIME},
    { /* Etc/GMT+12 */              "<-12>12",                          IN_SECONDS(12, 0, 0),     NO_TIME},
    { /* Africa/Casablanca */       "<+01>-1",                         -IN_SECONDS(1, 0, 0),      NO_TIME},
    { /* America/Araguaina */       "<-03>3",                           IN_SECONDS(3, 0, 0),      NO_TIME},
    { /* America/Asuncion */        "<-04>4<-03>,M10.1.0/0,M3.4.0/0",   IN_SECONDS(4, 0, 0),      IN_SECONDS(3, 0, 0)},
    { /* America/Los_Angeles */     "PST8PDT,M3.2.0,M11.1.0",           IN_SECONDS(8, 0, 0),      IN_SECONDS(7, 0, 0)},
    { /* America/New_York */        "EST5EDT,M3.2.0,M11.1.0",           IN_SECONDS(5, 0, 0),      IN_SECONDS(4, 0, 0)},
    { /* America/Scoresbysund */    "<-01>1<+00>,M3.5.0/0,M10.5.0/1",   IN_SECONDS(1, 0, 0),      IN_SECONDS(0, 0, 0)},
    { /* Asia/Colombo */            "<+0530>-5:30",                    -IN_SECONDS(5, 30, 0),     NO_TIME},
    { /* Europe/Berlin */           "CET-1CEST,M3.5.0,M10.5.0/3",      -IN_SECONDS(1, 0, 0),     -IN_SECONDS(2, 0, 0)},

    /// test parsing errors
    // 1. names are too long
#ifdef __PICOLIBC__
    /* glibc is more lenient about name lengths, don't check on that */
    {"JUSTEXCEEDI1:11:11",                                      0,   NO_TIME},
    {"AVERYLONGNAMEWHICHEXCEEDSTZNAMEMAX2:22:22",               0,   NO_TIME},
    {"FIRSTVERYLONGNAME3:33:33SECONDVERYLONGNAME4:44:44",       0,   0},
    {"<JUSTEXCEEDI>5:55:55",                                    0,   NO_TIME},
    {"<FIRSTVERYLONGNAME>3:33:33<SECONDVERYLONGNAME>4:44:44",   0,   0},
    {"<+JUSTEXCEED>5:55:55",                                    0,   NO_TIME},

    // 2. names are too short
    {"JU6:34:47",               0,   NO_TIME},
    {"HE6:34:47LO3:34:47",      0,   0},
    {"<AB>2:34:47",             0,   NO_TIME},
    {"<AB>2:34:47<CD>3:34:47",  0,   0},
#endif

    // 3. names contain invalid chars
    {"N?ME2:10:56",     0,   NO_TIME},
    {"N!ME2:10:56",     0,   NO_TIME},
    {"N/ME2:10:56",     0,   NO_TIME},
    {"N$ME2:10:56",     0,   NO_TIME},
    {"NAME?2:10:56",    0,   NO_TIME},
    {"?NAME2:10:56",    0,   NO_TIME},
    {"NAME?UNK4:21:15",                 0,   NO_TIME},
    {"NAME!UNK4:22:15NEXT/NAME4:23:15", 0,   NO_TIME},

    // 4. bogus strings
    {"NOINFO",          0,  NO_TIME},
    {"HOUR:16:18",      0,  NO_TIME},
    {"<BEGIN",          0,  NO_TIME},
    {"<NEXT:55",        0,  NO_TIME},
    {">WRONG<2:15:00",  0,  NO_TIME},
    {"ST<ART4:30:00",   0,  NO_TIME},
    //{"MANY8:00:00:00",  0,  NO_TIME},
    {"\0",              0,  NO_TIME},
    {"M\0STR7:30:36",   0,  NO_TIME}
};

// END test vectors

static int failed = 0;

#define TEST_ASSERT_EQUAL_INT_MESSAGE(...) assert_equal(__VA_ARGS__)
static void assert_equal(int lhs, int rhs, const char* msg)
{
    if (lhs != rhs)
    {
        printf("Assertion failed! Expected %d to equal %d. %s\n", lhs, rhs, msg);
        ++failed;
    }
}

static void test_TimezoneStrings(void)
{
    char buffer[128];

    for (size_t i = 0; i < (sizeof(test_timezones) / sizeof(struct tz_test)); ++i)
    {
        struct tz_test ptr = test_timezones[i];

        setenv("TZ", ptr.tzstr, 1);
        tzset();
 
        snprintf(buffer, 128, "winter time, timezone = \"%s\"", ptr.tzstr);
 
        struct tm winter_tm_copy = winter_tm; // copy
        TEST_ASSERT_EQUAL_INT_MESSAGE(winter_time + ptr.offset_seconds, mktime(&winter_tm_copy), buffer);

        if (ptr.dst_offset_seconds != NO_TIME)
        {
            snprintf(buffer, 128, "summer time, timezone = \"%s\"", ptr.tzstr);

            struct tm summer_tm_copy = summer_tm; // copy
            TEST_ASSERT_EQUAL_INT_MESSAGE(summer_time + ptr.dst_offset_seconds, mktime(&summer_tm_copy), buffer);
        }
    }
}

int main(void)
{
    test_TimezoneStrings();
    exit (failed);
}
