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.

This PR proposes changes to:

Core (units, players, creatures, game systems).
Scripts (bosses, spell scripts, creature scripts).
Database (SAI, creatures, etc).

New Files

HolidayDateCalculator.h/.cpp - Utility class that calculates holiday dates at runtime:
- Computus algorithm for Easter-based holidays (Noblegarden)
- Nth weekday calculation for floating holidays (Pilgrim's Bounty = 4th Thursday of November)
- 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	Fixed: Jan 22
Love is in the Air	Fixed: Feb 6
Noblegarden	Easter + 7 days
Children's Week	Fixed: Apr 30
Harvest Festival	Fixed: Sep 28
Pilgrim's Bounty	4th Thursday of November

Issues Addressed:

Closes fix(Core/DB/Events): Game Event Start Date & Events on Calendar #2890 (extends holiday dates beyond static SQL)

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.

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
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

Known Issues and TODO List:

May need additional holidays added to the rules table
In-game calendar testing needed

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

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

Nyeriah added the run-build Used to trigger the windows/mac/docker and matrix builds label Dec 5, 2025

blinkysc added the Ready to be Reviewed label Dec 5, 2025

sudlud reviewed Dec 5, 2025

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Nyeriah requested a review from Copilot December 5, 2025 11:57

Copilot started reviewing on behalf of Nyeriah December 5, 2025 11:58 View session

Copilot finished reviewing on behalf of Nyeriah December 5, 2025 12:03

Copilot AI reviewed Dec 5, 2025

View reviewed changes

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

sudlud reviewed Dec 5, 2025

View reviewed changes

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src/server/game/Events/GameEventMgr.cpp Outdated Show resolved Hide resolved

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

blinkysc added 4 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

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blinkysc commented Dec 4, 2025

Changes Proposed:

New Files

Modified Files

Holidays Covered

Issues Addressed:

SOURCE:

Tests Performed:

How to Test the Changes:

Known Issues and TODO List:

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