PassByDigitsHelper.h

#ifndef PASSBYDIGITSHELPER_H
#define PASSBYDIGITSHELPER_H

NSString * stringFromDateAndFormat(NSDate * date, NSString * format)
{
    NSDateFormatter *formatter = [NSDateFormatter new];
    [formatter setLocale:[NSLocale currentLocale]];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
    [formatter setDateFormat:format];

    NSString * string = [formatter stringFromDate:date];
    [formatter release];
    return string;
}

NSDate * dateFromStringAndFormat(NSString * string, NSString * format)
{
    NSDateFormatter *formatter = [NSDateFormatter new];
    [formatter setLocale:[NSLocale currentLocale]];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
    [formatter setDateFormat:format];

    NSDate * date = [formatter dateFromString:string];
    [formatter release];
    return date;
}

BOOL evalDateTimeHelper(NSString * format, char d0, char d1, BOOL reversed)
{
    if (reversed) {
        char tmp = d0;
        d0 = d1;
        d1 = tmp;
    }

    NSString * dateString =
        stringFromDateAndFormat(
            [NSDate dateWithTimeIntervalSinceNow:timeShift * 60],
            format
        );

    return d0 == [dateString characterAtIndex:0]
        && d1 == [dateString characterAtIndex:1];
}


struct Digits {
    BOOL (* eval) (struct Digits *, char, char);
    char digit0, digit1;
    BOOL reversed, isGracePeriod;
};

static BOOL evalCustom(struct Digits * config, char d0, char d1)
{
    return config->reversed
        ? d1 == config->digit0 && d0 == config->digit1
        : d0 == config->digit0 && d1 == config->digit1;
}

static BOOL evalTimeH(struct Digits * config, char d0, char d1)
{
    return evalDateTimeHelper(
        use24hFormat ? @"HH" : @"hh",
        d0, d1, config->reversed
    );
}

static BOOL evalTimeM(struct Digits * config, char d0, char d1)
{
    return evalDateTimeHelper(@"mm", d0, d1, config->reversed);
}

static BOOL evalDateD(struct Digits * config, char d0, char d1)
{
    return evalDateTimeHelper(@"dd", d0, d1, config->reversed);
}

static BOOL evalDateM(struct Digits * config, char d0, char d1)
{
    return evalDateTimeHelper(@"MM", d0, d1, config->reversed);
}

static BOOL evalBattR(struct Digits * config, char d0, char d1)
{
    if (config->reversed) {
        char tmp = d0;
        d0 = d1;
        d1 = tmp;
    }
    int level = (int) ([[UIDevice currentDevice] batteryLevel] * 100.0f);
    return d0 == '0' + ((level / 10) % 10)
        && d1 == '0' + (level % 10);
}

static BOOL evalBattU(struct Digits * config, char d0, char d1)
{
    if (config->reversed) {
        char tmp = d0;
        d0 = d1;
        d1 = tmp;
    }
    int level = 100 - (int) ([[UIDevice currentDevice] batteryLevel] * 100.0f);
    return d0 == '0' + ((level / 10) % 10)
        && d1 == '0' + (level % 10);
}

static BOOL evalGraceP(struct Digits * config, char d0, char d1)
{
    if (config->reversed) {
        char tmp = d0;
        d0 = d1;
        d1 = tmp;
    }
    digitsGracePeriod = (d0 - '0') * 60 + (d1 - '0') * 10;
    return YES;
}

enum DigitConfig : int {
    CONFIG_TIMEH    = 0,
    CONFIG_TIMEM    = 1,
    CONFIG_DATED    = 2,
    CONFIG_DATEM    = 3,
    CONFIG_BATTR    = 4,
    CONFIG_BATTU    = 5,
    CONFIG_GRACEP   = 6,
    CONFIG_CUSTOM   = 7
};

void parseDigitsConfiguration(struct Digits * digits,
    NSString * custom, int config, BOOL reversed)
{
    digits->reversed        = reversed;
    digits->isGracePeriod   = NO;

    switch(config) {
        case CONFIG_TIMEH:
            digits->eval = evalTimeH;
            return;
        case CONFIG_TIMEM:
            digits->eval = evalTimeM;
            return;
        case CONFIG_DATED:
            digits->eval = evalDateD;
            return;
        case CONFIG_DATEM:
            digits->eval = evalDateM;
            return;
        case CONFIG_BATTR:
            digits->eval = evalBattR;
            return;
        case CONFIG_BATTU:
            digits->eval = evalBattU;
            return;
        case CONFIG_GRACEP:
            digits->eval = evalGraceP;
            digits->isGracePeriod = YES;
            return;
        case CONFIG_CUSTOM:
        default:
            if ([custom length] == 2) {
                digits->digit0 = [custom characterAtIndex:0];
                digits->digit1 = [custom characterAtIndex:1];
            } else {
                digits->digit1 = digits->digit0 = '0';
            }
            digits->eval = evalCustom;
            return;
    }
}

struct Time {
    int hours, minutes;
};

BOOL parseTime(struct Time * time, NSString * timeString)
{
    char h0, h1, m0, m1;
    if ([timeString length] == 4) {
        h0 = '0';
        h1 = [timeString characterAtIndex:0];
        m0 = [timeString characterAtIndex:2];
        m1 = [timeString characterAtIndex:3];
    } else if ([timeString length] == 5) {
        h0 = [timeString characterAtIndex:0];
        h1 = [timeString characterAtIndex:1];
        m0 = [timeString characterAtIndex:3];
        m1 = [timeString characterAtIndex:4];
    } else {
        return NO;
    }

    if (h0 >= '0' && h0 <= '2'
    && h1 >= '0' && h1 <= (h0 == 2 ? '3' : '9')
    && m0 >= '0' && m0 <= '5'
    && m1 >= '0' && m1 <= '9'
    ) {
        time->hours     = (h0 - '0') * 10 + h1 - '0';
        time->minutes   = (m0 - '0') * 10 + m1 - '0';
        return YES;
    }
    return NO;
}

#else
#error "File already included"
#endif // PASSBYDIGITSHELPER_H