Item stat profiles: take the level bonus tables from the profile instead of the item's power-ups? #1303

Is your feature request related to a problem? Please describe.

#1290 adds item stat profiles: named sets of item formulas, in the shape of the MuMain client's item stat file, so that both sides can exchange them. A follow-up makes the game logic read them; #1288 checks that it computes the same values as today.

A profile also names a level bonus table for each stat it writes. For example, the profile default names "Defense Increase (Armors)" for the base defense. But today every base power-up of an item already names its own table (ItemBasePowerUpDefinition.BonusPerLevelTable). So after #1290, the level table of an item's stat is named in two places: on the item's power-up and in its profile. The configuration update makes them equal (an item with a table of its own gets a copy of its profile, e.g. thirdTierWing2), but later edits can make them differ, and then one of them is silently ignored.

The question for this issue: for the stats the client knows (damage, magic power, block rate, defense), should the game take the level table from the item's profile, as the client does, or keep taking it from the item's power-up, as today?

How the client does it (MuMain)

An item names its profile, and the profile names one table per stat from the table list of Data/Items/Stats/ItemStats.json. Items don't name tables.

// tables
{ "name": "defenseIncreaseArmors", "values": [0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 31, 36, 42, 49, 57, 66] }
// the profile "default"
"defense":    { "table": "defenseIncreaseArmors", "excellent": { "times": 12, "add": 4, "dropLevelDivisor": 5 }, … }
"magicPower": { "table": "magicPowerIncrease", "excellent": { "times": 25, "add": 5 }, "ancient": { "add": 2, "dropLevelDivisor": 60 }, "perLevelAfterHalving": 2 }
// an item, in Data/Items/Group08_Armor.json
{ "number": 9, "name": { "en": "Plate Armor", … }, "statProfile": "armor", … }

Magic power has one table for all staffs, sceptres and books ("Magic Power Increase", the same numbers as the armour table). The client adds the table and the excellent and ancient parts to the full magic power, halves the sum once, and adds perLevelAfterHalving × level (2 for staffs and books, 0 for sceptres).

How the server does it today (OpenMU)

• Every base power-up names its table. ItemPowerUpFactory.GetBasePowerUpWrappers adds the table's value at the item's level to the base value: Plate Armor's "Base Defense" (30) points to "Defense Increase (Armors)", so its defense at +9 is 30 + 27 = 57.
• The formulas are in code: ItemExtensions.GetRequirement (how requirements grow) and ItemPowerUpFactory.CreateExcellentAndAncientBasePowerUpWrappers (what excellent and ancient items get more).
• Staffs store their rise already halved (Legendary Staff: 59 ÷ 2 = 29.5) and use two tables, "Staff Rise (odd)" and "Staff Rise (even)". They are the client's table halved plus 2 per level, rounded up or down by the parity of the magic power. So the server computes the Legendary Staff at +9 as 29.5 + 32 = 61.5 (excellent 75.5), where the client shows 61 (excellent 76).

The flows

Today:

flowchart LR
    item["Plate Armor"] --> powerUp["Base power-up: Base Defense, base value 30"]
    powerUp -->|"Bonus Per Level Table"| table["Defense Increase (Armors): +27 at +9"]
    code["Formulas in code: ItemExtensions, ItemPowerUpFactory"] --> extras["Requirements, excellent and ancient bonuses"]

After #1290 as it stands, two places name the table:

flowchart LR
    item["Plate Armor"] --> powerUp["Base Defense, base value 30"]
    powerUp -->|"Bonus Per Level Table (used by the game)"| table["Defense Increase (Armors)"]
    item -->|"Stat Profile"| armor["Profile armor"]
    armor -->|"laid over"| default["Profile default"]
    default -->|"table of Base Defense (only for the exchange)"| table

Proposed, as the client:

flowchart LR
    item["Plate Armor"] --> powerUp["Base Defense, base value 30, no table"]
    item -->|"Stat Profile"| armor["Profile armor: 5 strength per option level"]
    armor -->|"laid over"| default["Profile default: formulas and tables"]
    default -->|"table of Base Defense"| table["Defense Increase (Armors)"]

The client:

flowchart LR
    item["Item: Plate Armor, statProfile armor"] --> armor["ItemStats.json: profile armor"]
    armor -->|"laid over"| default["ItemStats.json: default"]
    default -->|"defense.table"| table["tables: defenseIncreaseArmors"]

Describe the solution you'd like

For the stats the client knows, an item only knows its profile, and the profile names the table:

1. In the follow-up which lets the game read the profiles: base defense, physical damage, defense rate and shield defense take their level table from the item's profile (laid over default). The values stay the same, because the configuration update made the tables equal, and the comparison test of test(items): pin today's item requirement, power-up and price formulas for every item #1288 checks it.
2. A magic power fix, as its own PR afterwards: staffs, sceptres and books compute like the client: the full magic power, the one table "Magic Power Increase", the sum halved once, plus 2 per level (0 for sceptres). That changes values by up to 0.5 to match the client (Legendary Staff +9: 61.5 → 61, excellent 75.5 → 76), and it needs a configuration update for the staffs', sceptres' and books' power-ups.
3. A cleanup update: it removes BonusPerLevelTable from the base power-ups of these stats, so that the admin panel doesn't show a table which has no effect.

Other level tables (e.g. the running speed of some armour pieces) stay on their power-ups, until profiles can hold terms for any attribute (#1302). An item which needs a table of its own gets a profile of its own, as the configuration update of #1290 already does.

Describe alternatives you've considered

• Keep the power-up's table as the one the game uses, and the profile's table only describes the items for the exchange. Nothing changes in how values are computed; the export reports items whose table differs from their profile's, and the import writes a changed profile table onto the items. Two places stay.
• Move every level table into profiles at once, also running speed and the like. That needs terms for any attribute first (Item stat profiles: excellent and ancient terms for any attribute #1302).

Mockups

1. Today: Plate Armor in the admin panel. The level table sits on the item's power-up, and the formulas are in the code.

2. After: Plate Armor names its profile "armor". Its power-up keeps the base value; its own table pointer is removed by the cleanup update. ("2b-2" is the follow-up which lets the game read the profiles.)

3. After: the profile "default" with its level tables, excellent and ancient terms and requirement formulas, and the two drop level bonuses of the configuration.

4. After: the profile "armor" only writes 5 strength per option level. Plate Armor's values worked out, the same as today.

5. A level table only holds the numbers per item level, on both sides. Below: the client's one magic power table next to the server's two staff tables.

6. The comparison: the item's power-up or the profile names the table.

Additional context

Questions for the maintainers:

1. Should the profile name the level table for these stats (the proposal), or should the power-up stay the source?
2. Is it fine that the magic power fix changes values by up to 0.5, to match what the client shows?
3. Is it fine that a cleanup update removes BonusPerLevelTable from those power-ups?

Related: #1290 (the profiles), #1288 (the comparison test), #1302 (terms for any attribute), #1301 (the books' energy requirement), sven-n/MuMain#861 (the client's item sync), sven-n/MuMain#864 (the client side of #1302).