#include "TimeFormatters.h"
#include "configuration.h"
#include "gps/RTC.h"
#include "mesh/NodeDB.h"
#include <cstring>

bool deltaToTimestamp(uint32_t secondsAgo, uint8_t *hours, uint8_t *minutes, int32_t *daysAgo)
{
    // Cache the result - avoid frequent recalculation
    static uint8_t hoursCached = 0, minutesCached = 0;
    static uint32_t daysAgoCached = 0;
    static uint32_t secondsAgoCached = 0;
    static bool validCached = false;

    // Abort: if timezone not set
    if (strlen(config.device.tzdef) == 0) {
        validCached = false;
        return validCached;
    }

    // Abort: if invalid pointers passed
    if (hours == nullptr || minutes == nullptr || daysAgo == nullptr) {
        validCached = false;
        return validCached;
    }

    // Abort: if time seems invalid.. (> 6 months ago, probably seen before RTC set)
    if (secondsAgo > SEC_PER_DAY * 30UL * 6) {
        validCached = false;
        return validCached;
    }

    // If repeated request, don't bother recalculating
    if (secondsAgo - secondsAgoCached < 60 && secondsAgoCached != 0) {
        if (validCached) {
            *hours = hoursCached;
            *minutes = minutesCached;
            *daysAgo = daysAgoCached;
        }
        return validCached;
    }

    // Get local time
    uint32_t secondsRTC = getValidTime(RTCQuality::RTCQualityDevice, true); // Get local time

    // Abort: if RTC not set
    if (!secondsRTC) {
        validCached = false;
        return validCached;
    }

    // Get absolute time when last seen
    uint32_t secondsSeenAt = secondsRTC - secondsAgo;

    // Calculate daysAgo
    *daysAgo = (secondsRTC / SEC_PER_DAY) - (secondsSeenAt / SEC_PER_DAY); // How many "midnights" have passed

    // Get seconds since midnight
    uint32_t hms = (secondsRTC - secondsAgo) % SEC_PER_DAY;
    hms = (hms + SEC_PER_DAY) % SEC_PER_DAY;

    // Tear apart hms into hours and minutes
    *hours = hms / SEC_PER_HOUR;
    *minutes = (hms % SEC_PER_HOUR) / SEC_PER_MIN;

    // Cache the result
    daysAgoCached = *daysAgo;
    hoursCached = *hours;
    minutesCached = *minutes;
    secondsAgoCached = secondsAgo;

    validCached = true;
    return validCached;
}

void getTimeAgoStr(uint32_t agoSecs, char *timeStr, uint8_t maxLength)
{
    // Use an absolute timestamp in some cases.
    // Particularly useful with E-Ink displays. Static UI, fewer refreshes.
    uint8_t timestampHours, timestampMinutes;
    int32_t daysAgo;
    bool useTimestamp = deltaToTimestamp(agoSecs, &timestampHours, &timestampMinutes, &daysAgo);

    if (agoSecs < 120) // last 2 mins?
        snprintf(timeStr, maxLength, "%u seconds ago", agoSecs);
    // -- if suitable for timestamp --
    else if (useTimestamp && agoSecs < 15 * SECONDS_IN_MINUTE) // Last 15 minutes
        snprintf(timeStr, maxLength, "%u minutes ago", agoSecs / SECONDS_IN_MINUTE);
    else if (useTimestamp && daysAgo == 0) // Today
        snprintf(timeStr, maxLength, "Last seen: %02u:%02u", (unsigned int)timestampHours, (unsigned int)timestampMinutes);
    else if (useTimestamp && daysAgo == 1) // Yesterday
        snprintf(timeStr, maxLength, "Seen yesterday");
    else if (useTimestamp && daysAgo > 1) // Last six months (capped by deltaToTimestamp method)
        snprintf(timeStr, maxLength, "%li days ago", (long)daysAgo);
    // -- if using time delta instead --
    else if (agoSecs < 120 * 60) // last 2 hrs
        snprintf(timeStr, maxLength, "%u minutes ago", agoSecs / 60);
    // Only show hours ago if it's been less than 6 months. Otherwise, we may have bad data.
    else if ((agoSecs / 60 / 60) < (730 * 6))
        snprintf(timeStr, maxLength, "%u hours ago", agoSecs / 60 / 60);
    else
        snprintf(timeStr, maxLength, "unknown age");
}