feat(Core/Events): Add dynamic holiday date calculator #24038

blinkysc · 2025-12-04T20:41:32Z

Changes Proposed:

Replaces static SQL-based holiday dates with dynamic C++ calculation, eliminating the need for recurring SQL maintenance as years progress.

The game_event.start_time column in the database serves as an override for calculated dates. If start_time is set to a date in the current year or later, it will be used instead of the dynamically calculated date. This allows custom servers to override specific holiday dates without modifying the code.

This PR proposes changes to:

Core (units, players, creatures, game systems).
Scripts (bosses, spell scripts, creature scripts).
Database (removes holiday_dates table - no longer needed).

New Files

HolidayDateCalculator.h/.cpp - Utility class that calculates holiday dates at runtime:
- Lunar New Year calculation (Meeus Astronomical Algorithms)
- Computus algorithm for Easter-based holidays (Noblegarden)
- Nth weekday calculation for floating holidays (Pilgrim's Bounty)
- Autumn equinox / Winter solstice calculations (Harvest Festival, Winter Veil)
- Darkmoon Faire 3-location monthly rotation
- Fixed date handling for standard holidays
HolidayDateCalculatorTest.cpp - Unit tests covering years 1900-2200

Modified Files

GameEventMgr.cpp - Generates dynamic dates on load, DB overrides preserved for custom servers

Holidays Covered

Holiday	Calculation Type
Lunar Festival	Chinese New Year - 1 day (astronomical)
Love is in the Air	First Monday on or after Feb 3
Noblegarden	Easter Sunday + 1 day (Computus algorithm)
Children's Week	First Monday on or after Apr 25
Midsummer Fire Festival	Fixed Jun 21
Fireworks Spectacular	Fixed Jul 4
Pirates' Day	Fixed Sep 19
Brewfest	First Saturday on or after Sept 15, minus 7 days
Harvest Festival	Autumn equinox - 2 days (astronomical)
Hallow's End	Fixed Oct 18
Day of the Dead	Fixed Nov 1
Pilgrim's Bounty	4th Thursday of November - 4 days
Winter Veil	Winter solstice - 6 days (astronomical)
Darkmoon Faire (Elwynn)	First Sunday of Mar/Jun/Sep/Dec - 2 days
Darkmoon Faire (Mulgore)	First Sunday of Jan/Apr/Jul/Oct - 2 days
Darkmoon Faire (Terokkar)	First Sunday of Feb/May/Aug/Nov - 2 days

Client Limitation

While the algorithm calculates dates for any year (validated 1900-2200), the WoW 3.3.5a client uses a 5-bit year offset field, limiting displayable dates to years 2000-2031.

Issues Addressed:

Closes fix(Core/DB/Events): Game Event Start Date & Events on Calendar #2890 (extends holiday dates beyond static SQL)
Closes [World Events] Mismatched Holiday event dates between in-game/aowow/wowhead calendars chromiecraft/chromiecraft#6853
Closes Lunar Festival Active and Many Holidays Missing from Calendar #24291
Closes fix(DB/Misc) Added 2026 holiday_dates for Calendar #24293

SOURCE:

The changes have been validated through:

Live research (checked on live servers, e.g Classic WotLK, Retail, etc.)
Sniffs (remember to share them with the open source community!)
Video evidence, knowledge databases or other public sources (e.g forums, Wowhead, etc.)
The changes promoted by this pull request come partially or entirely from another project (cherry-pick).

Easter dates validated against known astronomical Easter tables. Thanksgiving dates validated against US calendar. Lunar New Year validated against astronomical sources. Equinox/solstice calculations use Jean Meeus algorithms.

Tests Performed:

This PR has been:

Tested in-game by the author.
Tested in-game by other community members/someone else other than the author/has been live on production servers.
This pull request requires further testing and may have edge cases to be tested.

Unit tests pass:

All holidays calculated correctly for 301 years (1900-2200)
Leap year edge cases verified (1900, 2000, 2100, 2200)
Easter Computus algorithm validated
Lunar New Year algorithm validated
Darkmoon Faire 3-location rotation validated
Pack/unpack roundtrip verified

How to Test the Changes:

This pull request can be tested by following the reproduction steps provided in the linked issue
This pull request requires further testing. Provide steps to test your changes.

Build the server with unit tests enabled
Run HolidayDateCalculatorTest to verify calculations
Start server and check calendar in-game
Verify holiday dates display correctly for current and future years
Verify Darkmoon Faire shows all 3 locations rotating monthly
Test override by setting custom start_time in game_event

Known Issues and TODO List:

Holiday dates verified against official Blizzard schedule
Darkmoon Faire 3-location rotation implemented
holiday_dates table removed (dates calculated dynamically)
In-game calendar tested

Replaces static SQL-based holiday dates with dynamic C++ calculation. Holidays are now computed at runtime using: - Computus algorithm for Easter-based holidays (Noblegarden) - Nth weekday calculation for floating holidays (Pilgrim's Bounty) - Fixed dates for standard holidays Includes unit tests covering years 1900-2200. DB overrides still supported for custom servers.

src/server/game/Events/GameEventMgr.cpp

src/server/game/Events/HolidayDateCalculator.cpp

src/server/game/Events/HolidayDateCalculator.h

sudlud · 2025-12-05T07:04:30Z

does this align with the entries in game_event table?

or even better could those entries be taken into account maybe

sudlud · 2025-12-05T07:07:12Z

it would be great if the calendar could actually reflect what game_event is configured for these events, right now the actual game_event handling and in game calendar are completely independent unfortunately. this pr now introduces another place where these get hardcoded.

sudlud · 2025-12-05T11:29:42Z

also is this one of your AI generated fixes?

Copilot

Pull request overview

This PR introduces dynamic holiday date calculation to replace static SQL-based holiday dates. It adds a new HolidayDateCalculator utility class that computes holiday dates at runtime using mathematical algorithms (Computus for Easter, nth-weekday calculation for Thanksgiving-like holidays, and fixed dates for regular holidays). The system generates dates for the current year plus 10 future years at server startup, while preserving database override capabilities for custom servers.

Key Changes:

New holiday date calculation system supporting three types: fixed dates, nth weekday of month, and Easter-relative dates
Comprehensive unit test coverage spanning 301 years (1900-2200) with edge case validation
Integration with existing GameEventMgr that generates dynamic dates while maintaining DB override compatibility

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 11 comments.

File	Description
`HolidayDateCalculator.h`	Declares calculator class with Easter (Computus), nth-weekday, and fixed-date calculation methods; defines holiday rule structures and enums
`HolidayDateCalculator.cpp`	Implements Gregorian Computus algorithm for Easter, nth-weekday finder, date packing/unpacking for WoW's 2000-2031 format, and holiday rule configuration
`HolidayDateCalculatorTest.cpp`	Comprehensive test suite with 485 lines covering known Easter dates, weekday calculations, pack/unpack roundtrips, leap years, and century boundaries across 1900-2200
`GameEventMgr.cpp`	Modified `LoadHolidayDates()` to generate 11 years of dynamic dates per holiday, then load DB overrides; preserves backward compatibility

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src/server/game/Events/GameEventMgr.cpp

src/server/game/Events/HolidayDateCalculator.cpp

src/server/game/Events/HolidayDateCalculator.h

src/server/game/Events/HolidayDateCalculator.cpp

src/server/game/Events/GameEventMgr.cpp

- Use std::chrono with thread-safe localtime_r/localtime_s - Add const to applicable variables - Change Weekday to enum class - Add source reference for Computus algorithm - Add unit test for packed date year limitations

blinkysc · 2025-12-05T13:56:40Z

does this align with the entries in game_event table?
it would be great if the calendar could actually reflect what game_event is configured for these events, right now the actual game_event handling and in game calendar are completely independent unfortunately. this pr now introduces another place where these get hardcoded.

No currently it doesn't... I'll see what I can do today

also is this one of your AI generated fixes?

I use AI to help me quite a bit yeah, but its more like don't trust and verify/read through exactly what I'm doing. It's why also I wanted the unit tests.

src/server/game/Events/GameEventMgr.cpp

src/server/game/Events/HolidayDateCalculator.cpp

sudlud · 2025-12-06T05:46:21Z

darkmoon faires dates are already beeing calculated in the core via the dbc configuration, the dbc entry is linked in game_event see e.g.

azerothcore-wotlk/src/server/game/Events/GameEventMgr.cpp

Line 1840 in 8d31bce

void GameEventMgr::SetHolidayEventTime(GameEventData& event)

blinkysc · 2025-12-06T19:19:54Z

After digging deeper into this, I want to clarify how the integration actually works:

The dynamic dates DO feed into game_event timing - they're not independent systems.

The loading order in World.cpp is:

LoadHolidayDates() - calculates dynamic dates → writes to sHolidaysStore->Date[]
LoadFromDB() → LoadEvents() → SetHolidayEventTime()

SetHolidayEventTime() (line 1880) reads from holiday->Date[] to set gameEvent.Start. So when we populate Date[] dynamically, both the calendar AND the game event timing use the same calculated dates.

HolidayDateCalculator
│
▼
sHolidaysStore->Date[] ←── Single source of truth
│
├──► Calendar display
│
└──► SetHolidayEventTime() → gameEvent.Start

The only thing "hardcoded" in C++ is the calculation rules (Easter algorithm, "4th Thursday of November" logic), not the dates themselves. The holiday_dates table still works as an override layer for custom servers or cultural differences.

blinkysc · 2025-12-06T19:33:09Z

darkmoon faires dates are already beeing calculated in the core via the dbc configuration, the dbc entry is linked in game_event see e.g.

azerothcore-wotlk/src/server/game/Events/GameEventMgr.cpp

Line 1840 in 8d31bce

void GameEventMgr::SetHolidayEventTime(GameEventData& event)

this PR doesn't change that. Darkmoon uses Looping=1 with a fixed occurence interval, which works because it recurs at regular intervals

Implement Jean Meeus algorithm to calculate Chinese New Year dates dynamically using astronomical new moon calculation instead of a static lookup table. CNY falls on the new moon between Jan 21-Feb 20. - Add CalculateLunarNewYear() with full Meeus algorithm - Add DateToJulianDay/JulianDayToDate conversion functions - Add CalculateNewMoon() with 15 correction terms from Table 49.A - Update Lunar Festival rule to use LUNAR_NEW_YEAR calculation type - Add 5 unit tests covering years 1900-2200 with 100% accuracy

Add 7 additional fixed-date holidays to the dynamic system: - Midsummer Fire Festival (Jun 21) - Fireworks Spectacular (Jul 4) - Pirates' Day (Sep 19) - Brewfest (Sep 20) - Hallow's End (Oct 18) - Day of the Dead (Nov 1) - Winter Veil (Dec 15) Total holidays now managed by dynamic system: 13

- Alphabetize HolidayDateCalculator.h include - Use explicit time_point type instead of auto

blinkysc · 2025-12-20T00:35:30Z

I think maybe what I should do to tidy this up is likely just generate 3 years vs 10 (client limitation anyways) as well potentially have game_event.start_time be the override since it's human readable to begin with? Big question I have is should we rename to something like start_time_override to be more specific? And it should be that it's blank for the most part unless admins want to change those dates?

EDIT: Refactored for these changes other than renaming sql

This reverts commit d4a6722.

This reverts commit 7f04420.

This reverts commit 5bb07f3.

- otherwise events would disappear right on their ending date after restart - also you can look very far back in the calendar

- Add all three Darkmoon Faire locations (374, 375, 376) to HolidayRules - Special handling in LoadHolidayDates() for multi-date holidays (4 per year) - Set Duration[0] = 168 hours (7 days) if not set in DBC - Use -2 day offset (Friday start for building phase before Sunday faire) - Add GetDarkmoonFaireDates dayOffset parameter for configurable offset - Add integration test verifying Darkmoon entries in HolidayRules

- Change from month % 3 (3 locations) to month % 2 (2 locations) - Odd months (Jan, Mar, May...) = Alliance Elwynn (374) - Even months (Feb, Apr, Jun...) = Horde Mulgore (375) - Remove Terokkar (376) as it's not used in WotLK

Updated CalculateHolidayDate() to use month % 2 instead of month % 3 for proper 2-location alternation (Elwynn odd months, Mulgore even months). Also updated unit tests to match the WotLK 2-location pattern.

Rotation: Mulgore (Jan/Apr/Jul/Oct) -> Terokkar (Feb/May/Aug/Nov) -> Elwynn (Mar/Jun/Sep/Dec) Uses month % 3 pattern for location offset calculation.

blinkysc · 2026-01-02T15:40:46Z

Wiki PR azerothcore/wiki#1153

…me_event - these also get calculated automatically now

sudlud · 2026-01-02T15:55:10Z

tested again on the latest revision. dates in the in-game calendar look good to me for the last year and the upcoming year visible in the client

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 12 comments.

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src/server/game/Events/HolidayDateCalculator.cpp

data/sql/updates/pending_db_world/rev_1767341430742537600.sql

src/server/game/Events/HolidayDateCalculator.h

src/server/game/Events/HolidayDateCalculator.cpp

src/server/game/Events/GameEventMgr.cpp

src/server/game/Events/HolidayDateCalculator.cpp

src/test/server/game/Events/HolidayDateCalculatorTest.cpp

src/server/game/Events/HolidayDateCalculator.cpp

src/server/game/Events/GameEventMgr.cpp

- Clamp years before 2000 to offset 0 to prevent integer underflow - Change per-date holiday logging from LOG_INFO to LOG_DEBUG - Fix Metonic cycle test comment to explain 30-day tolerance

Tests Apr 25, Apr 30, and Dec 31 edge cases where the calculated weekday may roll into the next month (or next year for Dec 31).

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 9 comments.

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data/sql/updates/pending_db_world/rev_1767341430742537600.sql

src/server/game/Events/GameEventMgr.cpp

src/server/game/Events/HolidayDateCalculator.cpp

src/server/game/Events/GameEventMgr.cpp

src/test/server/game/Events/HolidayDateCalculatorTest.cpp

src/server/game/Events/HolidayDateCalculator.cpp

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

github-actions bot added CORE Related to the core UnitTests file-cpp Used to trigger the matrix build labels Dec 4, 2025

blinkysc force-pushed the feature/dynamic-holiday-date-calculator branch from 5d19425 to 61eee6f Compare December 4, 2025 20:43

blinkysc requested a review from sudlud December 4, 2025 20:52

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blinkysc added 2 commits December 5, 2025 07:30

Address PR review feedback

d312805

- Use std::chrono with thread-safe localtime_r/localtime_s - Add const to applicable variables - Change Weekday to enum class - Add source reference for Computus algorithm - Add unit test for packed date year limitations

Cap year generation at 2030

9529dba

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src/server/game/Events/GameEventMgr.cpp Outdated Show resolved Hide resolved

src/server/game/Events/HolidayDateCalculator.cpp Outdated Show resolved Hide resolved

blinkysc added 6 commits December 6, 2025 14:35

style(Core/Events): Fix include order and explicit type

b78f5bf

- Alphabetize HolidayDateCalculator.h include - Use explicit time_point type instead of auto

docs(Core/Events): Add Lunar New Year algorithm reference

f27bbfb

refactor: change to generate just 2 years per client

df9607c

refactor: 3 year for client cal overlap

64a86dd

sudlud added 4 commits January 2, 2026 09:00

Revert "fix doxygen comment"

2d501ec

This reverts commit d4a6722.

Revert "Update src/server/game/Events/HolidayDateCalculator.cpp"

4e24945

This reverts commit 7f04420.

Revert "exclude brewfest for now, add todo comment"

2630efa

This reverts commit 5bb07f3.

correctly link brewfest building event in ironforge to brewfest

04c32e1

github-actions bot added the DB related to the SQL database label Jan 2, 2026

sudlud and others added 7 commits January 2, 2026 09:48

remove start end end times from automatically handled events

b08ce9d

drop unused table holiday_dates

ae52c3e

also fill previous year in the calendar

868e548

- otherwise events would disappear right on their ending date after restart - also you can look very far back in the calendar

Fix Darkmoon Faire location rotation for WotLK

074a6a6

- Change from month % 3 (3 locations) to month % 2 (2 locations) - Odd months (Jan, Mar, May...) = Alliance Elwynn (374) - Even months (Feb, Apr, Jun...) = Horde Mulgore (375) - Remove Terokkar (376) as it's not used in WotLK

fix Darkmoon Faire location rotation to use month % 2 for WotLK

395e268

Updated CalculateHolidayDate() to use month % 2 instead of month % 3 for proper 2-location alternation (Elwynn odd months, Mulgore even months). Also updated unit tests to match the WotLK 2-location pattern.

add Terokkar as third Darkmoon Faire location with 3-location rotation

6c4182c

Rotation: Mulgore (Jan/Apr/Jul/Oct) -> Terokkar (Feb/May/Aug/Nov) -> Elwynn (Mar/Jun/Sep/Dec) Uses month % 3 pattern for location offset calculation.

also clear start end end dates of darkmoon fair related entries in ga…

3816950

…me_event - these also get calculated automatically now

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blinkysc added 2 commits January 2, 2026 10:26

fix year underflow in PackDate, reduce log verbosity

da02ea4

- Clamp years before 2000 to offset 0 to prevent integer underflow - Change per-date holiday logging from LOG_INFO to LOG_DEBUG - Fix Metonic cycle test comment to explain 30-day tolerance

add month boundary tests for WeekdayOnOrAfter

9656038

Tests Apr 25, Apr 30, and Dec 31 edge cases where the calculated weekday may roll into the next month (or next year for Dec 31).

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Update data/sql/updates/pending_db_world/rev_1767341430742537600.sql

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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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sudlud added To Be Merged and removed Ready to be Reviewed labels Jan 2, 2026

codestyle

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sudlud merged commit c1d753f into azerothcore:master Jan 2, 2026
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github-actions bot mentioned this pull request Jan 3, 2026

Wiki Update Needed: feat(Core/Events): Add dynamic holiday date calculator azerothcore/wiki#1154

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feat(Core/Events): Add dynamic holiday date calculator #24038

feat(Core/Events): Add dynamic holiday date calculator #24038

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blinkysc commented Dec 4, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Changes Proposed:

New Files

Modified Files

Holidays Covered

Client Limitation

Issues Addressed:

SOURCE:

Tests Performed:

How to Test the Changes:

Known Issues and TODO List:

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