Mana

The mana module manages the player's spell resource. It is composed of ManaComponent, which stores the mana pool, and ManaSystem, which handles passive regeneration each frame.

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ManaComponent

ManaComponent stores an entity's current, base, and maximum mana via StatValue, plus a regeneration rate. It conforms to StatProvidable.

public class ManaComponent: StatProvidable {
    public var value: StatValue
    public var regenRate: Float  // mana per second

    public init(base: Float, max: Float, regenRate: Float = 0)
}

Field	Description
value.base	Starting mana at initialisation
value.current	Live mana value, modified by spending and regeneration
value.max	Maximum mana ceiling
regenRate	Mana restored per second. 0 disables passive regeneration.

Example:

// Player with 100 max mana, starts full, regenerates 5 mana/sec
world.addComponent(
    component: ManaComponent(base: 100, max: 100, regenRate: 5),
    to: player
)

// Entity with mana pool but no passive regen
world.addComponent(
    component: ManaComponent(base: 60, max: 60),
    to: entity
)

Spending Mana

To consume mana (e.g. when casting a spell), decrement value.current directly. To check whether the player can afford a spell before casting:

if let mana = world.getComponent(type: ManaComponent.self, for: player),
   mana.value.current >= spellCost {
    // proceed with cast
}

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ManaSystem

ManaSystem handles passive mana regeneration. It has no system dependencies and declares no priority, so it runs at the framework's default order.

Each frame, for every entity with a ManaComponent:

1. Skip if regenRate is 0 or below.
2. Skip if value.current is already at max (no wasted computation or floating-point drift).
3. Add regenRate × deltaTime to value.current.
4. Clamp current to max via clampToMax().

// Effective regen per frame (at 60 fps, deltaTime ≈ 0.0167)
regenAmount = regenRate * Float(deltaTime)

ManaSystem only regenerates — it never spends mana. Spending is the responsibility of the system or logic that consumes it (e.g. a spell-casting system).

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Update Loop Summary

Each frame:

1. ManaSystem — for each entity with ManaComponent and regenRate > 0, tick current upward and clamp to max.
2. Spell/ability system (your implementation) — checks current, deducts cost, clamps to min.

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Configuring Mana for Different Entity Types

Use case	Configuration
Player with slow regen	ManaComponent(base: 100, max: 100, regenRate: 3)
Player with fast regen	ManaComponent(base: 100, max: 100, regenRate: 15)
No passive regen (potion-only)	ManaComponent(base: 100, max: 100) — default regenRate: 0
Enemy with a mana pool	Same as above; ManaSystem processes any entity with the component

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Dependencies

Dependency	Role
StatValue	Underlying value type for ManaComponent
ManaComponent	Read and modified each frame for regen

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