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+-- railwaytime.lua
+-- Advtrains uses a desynchronized time for train movement. Everything is counted relative to this time counter.
+-- The advtrains-internal time is in no way synchronized to the real-life time, due to:
+-- - Lag
+-- - Server stops/restarts
+-- However, this means that implementing a "timetable" system using the "real time" is not practical. Therefore,
+-- we introduce a custom time system, the RWT(Railway Time), which has nothing to do with RLT(Real-Life Time)
+-- RWT has a time cycle of 1 hour. This should be sufficient for most train lines that will ever be built in Minetest.
+-- A RWT looks like this: 37;25
+-- The ; is to distinguish it from a normal RLT (which has colons e.g. 12:34:56). Left number is minutes, right number is seconds.
+-- The minimum RWT is 00;00, the maximum is 59;59.
+-- It is OK to leave one places out at either end, esp. when writing relative times, such as:
+-- 43;3 22;0 2;30 0;10 ;10
+-- Those places are then filled with zeroes. Indeed, ";" would be valid for 00;00 .
+
+-- There is an "adapt mode", which was proposed by gpcf, and results in RWT automatically adapting itself to real-world time.
+-- It works by shifting the minute/second after the realtime minute/second, adjusting the cycle value as needed.
+
+-- Using negative times is discouraged. If you need a negative time, you may insert a minus (-) ONLY in the "c" place
+
+--[[
+1;23;45 = {
+ s=45,
+ m=23,
+ c=1, -- Cycle(~hour), not displayed most time
+}
+
+Railway times can exist in 3 forms:
+- as table (see above)
+- as string (like "12;34")
+- as number (of seconds)
+
+Forms are automagically converted as needed by the converter functions to_*
+To be sure a rwt is in the required form, explicitly use a converter.
+
+]]
+
+local rwt = {}
+
+--Time Stamp (Seconds since start of world)
+local e_time = 0
+local e_has_loaded = false
+
+local setting_rwt_real = minetest.settings:get("advtrains_lines_rwt_realtime")
+if setting_rwt_real=="" then
+ setting_rwt_real = "independent"
+end
+
+local e_last_epoch -- last real-time timestamp
+
+-- Advance RWT to match minute/second to the current real-world time
+-- only accounts for the minute/second part, leaves hour/cycle untouched
+local function adapt_real_time()
+ local datetab = os.date("*t")
+ local real_sectotal = 60*datetab.min + datetab.sec
+
+ local rwttab = rwt.now()
+ local rwt_sectotal = 60*rwttab.m + rwttab.s
+
+ --calculate the difference and take it %3600 (seconds/hour) to always move forward
+ local secsfwd = (real_sectotal - rwt_sectotal) % 3600
+
+ atlog("[lines][rwt] Skipping",secsfwd,"seconds forward to sync rwt (",rwt.to_string(rwttab),") to real time (",os.date("%H:%M:%S"),")")
+
+ e_time = e_time + secsfwd
+end
+
+function rwt.set_time(t)
+ e_time = t or 0
+ if setting_rwt_real == "adapt_real" then
+ adapt_real_time()
+ end
+ atlog("[lines][rwt] Initialized railway time: ",rwt.to_string(e_time))
+ e_last_epoch = os.time()
+
+ e_has_loaded = true
+end
+
+function rwt.get_time()
+ return e_time
+end
+
+function rwt.step(dt)
+ if not e_has_loaded then
+ rwt.set_time(0)
+ end
+
+ if setting_rwt_real=="independent" then
+ -- Regular stepping with dtime
+ e_time = e_time + dt
+ else
+ -- advance with real-world time
+ local diff = os.time() - e_last_epoch
+ e_last_epoch = os.time()
+
+ if diff>0 then
+ e_time = e_time + diff
+ end
+ end
+end
+
+function rwt.now()
+ return rwt.to_table(e_time)
+end
+
+function rwt.new(c, m, s)
+ return {
+ c = c or 0,
+ m = m or 0,
+ s = s or 0
+ }
+end
+function rwt.copy(rwtime)
+ local rwtimet = rwt.to_table(rwtime)
+ return {
+ c = rwtimet.c or 0,
+ m = rwtimet.m or 0,
+ s = rwtimet.s or 0
+ }
+end
+
+function rwt.to_table(rwtime)
+ if type(rwtime) == "table" then
+ return rwtime
+ elseif type(rwtime) == "string" then
+ return rwt.parse(rwtime)
+ elseif type(rwtime) == "number" then
+ local res = {}
+ local seconds = atfloor(rwtime)
+ res.s = seconds % 60
+ local minutes = atfloor(seconds/60)
+ res.m = minutes % 60
+ res.c = atfloor(minutes/60)
+ return res
+ end
+end
+
+function rwt.to_secs(rwtime, c_over)
+ local res = rwtime
+ if type(rwtime) == "string" then
+ res = rwt.parse(rwtime)
+ elseif type(rwtime) == "number" then
+ return rwtime
+ end
+ if type(res)=="table" then
+ return (c_over or res.c)*60*60 + res.m*60 + res.s
+ end
+end
+
+function rwt.to_string(rwtime_p, no_cycle)
+ local rwtime = rwt.to_table(rwtime_p)
+ if rwtime.c~=0 and not no_cycle then
+ return string.format("%d;%02d;%02d", rwtime.c, rwtime.m, rwtime.s)
+ else
+ return string.format("%02d;%02d", rwtime.m, rwtime.s)
+ end
+end
+
+---
+
+local function v_n(str, cpl)
+ if not str then return nil end
+ if str == "" then
+ return 0
+ end
+ local n = tonumber(str)
+ if not cpl and (n<0 or n>59) then
+ return nil
+ end
+ return n
+end
+
+function rwt.parse(str)
+ --atdebug("parse",str)
+ --3-value form
+ local str_c, str_m, str_s = string.match(str, "^(%-?%d?%d?);(%d%d);(%d?%d?)$")
+ if str_c and str_m and str_s then
+ --atdebug("3v",str_c, str_m, str_s)
+ local c, m, s = v_n(str_c, true), v_n(str_m), v_n(str_s)
+ if c and m and s then
+ return rwt.new(c,m,s)
+ end
+ end
+ --2-value form
+ local str_m, str_s = string.match(str, "^(%d?%d?);(%d?%d?)$")
+ if str_m and str_s then
+ --atdebug("2v",str_m, str_s)
+ local m, s = v_n(str_m), v_n(str_s)
+ if m and s then
+ return rwt.new(0,m,s)
+ end
+ end
+end
+
+---
+
+function rwt.add(t1, t2)
+ local t1s = rwt.to_secs(t1)
+ local t2s = rwt.to_secs(t2)
+ return rwt.to_table(t1s + t2s)
+end
+
+-- How many seconds FROM t1 TO t2
+function rwt.diff(t1, t2)
+ local t1s = rwt.to_secs(t1)
+ local t2s = rwt.to_secs(t2)
+ return t2s - t1s
+end
+
+-- Subtract t2 from t1 (inverted argument order compared to diff())
+function rwt.sub(t1, t2)
+ return rwt.to_table(rwt.diff(t2, t1))
+end
+
+-- Adjusts t2 by thresh and then returns time from t1 to t2
+function rwt.adj_diff(t1, t2, thresh)
+ local newc = rwt.adjust_cycle(t2, thresh, t1)
+ local t1s = rwt.to_secs(t1)
+ local t2s = rwt.to_secs(t2, newc)
+ return t1s - t2s
+end
+
+
+
+-- Threshold values
+-- "reftime" is the time to which this is made relative and defaults to now.
+rwt.CA_FUTURE = 60*60 - 1 -- Selected so that time lies at or in the future of reftime (at nearest point in time)
+rwt.CA_FUTURES = 60*60 -- Same, except when times are equal, advances one full cycle
+rwt.CA_PAST = 0 -- Selected so that time lies at or in the past of reftime
+rwt.CA_PASTS = -1 -- Same, except when times are equal, goes back one full cycle
+rwt.CA_CENTER = 30*60 -- If time is within past 30 minutes of reftime, selected as past, else selected as future.
+
+-- Adjusts the "cycle" value of a railway time to be in some relation to reftime.
+-- Returns new cycle
+function rwt.adjust_cycle(rwtime, reftime_p, thresh)
+ local reftime = reftime_p or rwt.now()
+
+ local reftimes = rwt.to_secs(reftime)
+
+ local rwtimes = rwt.to_secs(rwtime, 0)
+ local timeres = reftimes + thresh - rwtimes
+ local cycles = atfloor(timeres / (60*60))
+
+ return cycles
+end
+
+function rwt.adjust(rwtime, reftime, thresh)
+ local cp = rwt.copy(rwtime)
+ cp.c = rwt.adjust_cycle(rwtime, reftime, thresh)
+ return cp
+end
+
+-- Useful for departure times: returns time (in seconds)
+-- until the next (adjusted FUTURE) occurence of deptime is reached
+-- in this case, rwtime is used as reftime and deptime should lie in the future of rwtime
+-- rwtime defaults to NOW
+function rwt.get_time_until(deptime, rwtime_p)
+ local rwtime = rwtime_p or rwt.now()
+ return rwt.adj_diff(rwtime, deptime, rwt.CA_FUTURE)
+end
+
+
+-- Helper functions for handling "repeating times" (rpt)
+-- Those are generic declarations for time intervals like "every 5 minutes", with an optional offset
+-- ( /02;00-00;45 in timetable syntax
+
+-- Get the time (in seconds) until the next time this rpt occurs
+function rwt.time_to_next_rpt(rwtime, rpt_interval, rpt_offset)
+ local rpti_s = rwt.to_secs(rpt_interval)
+
+ return (rpti_s - rwt.time_from_last_rpt(rwtime, rpti_s, rpt_offset)) % rpti_s
+ -- Modulo is just there to clip a false value of rpti_s to 0
+end
+
+
+-- Get the time (in seconds) since the last time this rpt occured
+function rwt.time_from_last_rpt(rwtime, rpt_interval, rpt_offset)
+ local rwtime_s = rwt.to_secs(rwtime)
+ local rpti_s = rwt.to_secs(rpt_interval)
+ local rpto_s = rwt.to_secs(rpt_offset)
+
+ return ((rwtime_s - rpto_s) % rpti_s)
+end
+
+-- From rwtime, get the next time that is divisible by rpt_interval offset by rpt_offset
+function rwt.next_rpt(rwtime, rpt_interval, rpt_offset)
+ local rwtime_s = rwt.to_secs(rwtime)
+ local rpti_s = rwt.to_secs(rpt_interval)
+ local time_from_last = rwt.time_from_last_rpt(rwtime_s, rpti_s, rpt_offset)
+
+ local res_s = rwtime_s - time_from_last + rpti_s
+
+ return rwt.to_table(res_s)
+end
+
+-- from rwtime, get the last time that this rpt matched (which is actually just next_rpt - rpt_offset
+function rwt.last_rpt(rwtime, rpt_interval, rpt_offset)
+ local rwtime_s = rwt.to_sec(rwtime)
+ local rpti_s = rwt.to_sec(rpt_interval)
+ local time_from_last = rwt.time_from_last_rpt(rwtime, rpt_interval, rpt_offset)
+
+ local res_s = rwtime_s - time_from_last
+
+ return rwt.to_table(res_s)
+end
+
+
+advtrains.lines.rwt = rwt