rpg-mcp

/** * Concentration System - Manages concentration spell mechanics * Handles concentration checks, breaking concentration, and duration tracking */ import { ConcentrationState, ConcentrationCheckResult, BreakConcentrationRequest } from '../../schema/concentration.js'; import { Character, NPC } from '../../schema/character.js'; import { ConcentrationRepository } from '../../storage/repos/concentration.repo.js'; import { CharacterRepository } from '../../storage/repos/character.repo.js'; /** * Calculate the DC for a concentration save after taking damage * DC = 10 or half the damage taken, whichever is higher */ export function calculateConcentrationDC(damageAmount: number): number { const halfDamage = Math.floor(damageAmount / 2); return Math.max(10, halfDamage); } /** * Roll a constitution saving throw for concentration */ export function rollConcentrationSave(constitutionModifier: number): { roll: number; total: number } { const roll = Math.floor(Math.random() * 20) + 1; const total = roll + constitutionModifier; return { roll, total }; } /** * Check if concentration is maintained after taking damage */ export function checkConcentration( character: Character | NPC, damageAmount: number, concentrationRepo: ConcentrationRepository ): ConcentrationCheckResult { const concentration = concentrationRepo.findByCharacterId(character.id); if (!concentration) { return { characterId: character.id, spell: 'none', broken: false, reason: 'damage', }; } const dc = calculateConcentrationDC(damageAmount); const constitutionModifier = Math.floor((character.stats.con - 10) / 2); const { roll, total } = rollConcentrationSave(constitutionModifier); const success = total >= dc; return { characterId: character.id, spell: concentration.activeSpell, broken: !success, reason: success ? 'damage' : 'failed_save', saveRoll: roll, saveDC: dc, saveTotal: total, damageAmount, constitutionModifier, }; } /** * Break concentration for a character * This handles: * - Automatic breaks (incapacitated, death, new spell) * - Voluntary breaks * - Failed concentration saves */ export function breakConcentration( request: BreakConcentrationRequest, concentrationRepo: ConcentrationRepository, characterRepo: CharacterRepository ): ConcentrationCheckResult { const concentration = concentrationRepo.findByCharacterId(request.characterId); if (!concentration) { return { characterId: request.characterId, spell: 'none', broken: false, reason: request.reason, }; } const spell = concentration.activeSpell; // Delete concentration record concentrationRepo.delete(request.characterId); // Update character's concentrating_on field to null const character = characterRepo.findById(request.characterId); if (character) { characterRepo.update(request.characterId, { concentratingOn: null, }); } return { characterId: request.characterId, spell, broken: true, reason: request.reason, damageAmount: request.damageAmount, }; } /** * Start concentration on a spell */ export function startConcentration( characterId: string, spellName: string, spellLevel: number, currentRound: number, maxDuration: number | undefined, targetIds: string[] | undefined, concentrationRepo: ConcentrationRepository, characterRepo: CharacterRepository ): void { // Break any existing concentration first if (concentrationRepo.isConcentrating(characterId)) { breakConcentration( { characterId, reason: 'new_spell' }, concentrationRepo, characterRepo ); } // Create new concentration state const concentration: ConcentrationState = { characterId, activeSpell: spellName, spellLevel, startedAt: currentRound, maxDuration, targetIds, saveDCBase: 10, }; concentrationRepo.create(concentration); // Update character's concentrating_on field characterRepo.update(characterId, { concentratingOn: spellName, }); } /** * Check if concentration has exceeded its duration */ export function checkConcentrationDuration( characterId: string, currentRound: number, concentrationRepo: ConcentrationRepository, characterRepo: CharacterRepository ): ConcentrationCheckResult | null { const concentration = concentrationRepo.findByCharacterId(characterId); if (!concentration) { return null; } // No duration limit - concentration continues if (!concentration.maxDuration) { return null; } const roundsElapsed = currentRound - concentration.startedAt; if (roundsElapsed >= concentration.maxDuration) { // Duration exceeded - break concentration return breakConcentration( { characterId, reason: 'duration' }, concentrationRepo, characterRepo ); } return null; } /** * Get active concentration for a character */ export function getConcentration( characterId: string, concentrationRepo: ConcentrationRepository ): ConcentrationState | null { return concentrationRepo.findByCharacterId(characterId); } /** * Check for automatic concentration breaks (incapacitated, death) * This should be called when a character's conditions change */ export function checkAutomaticConcentrationBreak( character: Character | NPC, concentrationRepo: ConcentrationRepository, characterRepo: CharacterRepository ): ConcentrationCheckResult | null { if (!concentrationRepo.isConcentrating(character.id)) { return null; } // Check for death if (character.hp <= 0) { return breakConcentration( { characterId: character.id, reason: 'death' }, concentrationRepo, characterRepo ); } // Check for incapacitated condition const incapacitatingConditions = [ 'unconscious', 'stunned', 'paralyzed', 'petrified', ]; const hasIncapacitatingCondition = character.conditions?.some( (condition: any) => { if (typeof condition === 'string') { return incapacitatingConditions.includes(condition.toLowerCase()); } if (typeof condition === 'object' && condition.name) { return incapacitatingConditions.includes(condition.name.toLowerCase()); } return false; } ); if (hasIncapacitatingCondition) { return breakConcentration( { characterId: character.id, reason: 'incapacitated' }, concentrationRepo, characterRepo ); } return null; }