import type { GameState, AchievementState, AchievementDefinition } from '@ai-tycoon/shared';

export interface AchievementTickResult {
  achievements: AchievementState;
  newAchievements: string[];
}

const ERA_INDEX: Record<string, number> = { startup: 0, scaleup: 1, bigtech: 2, agi: 3 };

function getFieldValue(state: GameState, field: string): number {
  if (field === 'meta._eraIndex') return ERA_INDEX[state.meta.currentEra] ?? 0;
  if (field === 'meta._deployedModelCount') return state.models.baseModels.filter(m => m.isDeployed).length;
  const parts = field.split('.');
  let current: unknown = state;
  for (const part of parts) {
    if (current == null || typeof current !== 'object') return 0;
    current = (current as Record<string, unknown>)[part];
  }
  return typeof current === 'number' ? current : 0;
}

function checkCondition(state: GameState, def: AchievementDefinition): boolean {
  const value = getFieldValue(state, def.condition.field);
  switch (def.condition.operator) {
    case 'gt': return value > def.condition.value;
    case 'gte': return value >= def.condition.value;
    case 'eq': return value === def.condition.value;
    default: return false;
  }
}

export function processAchievements(
  state: GameState,
  definitions: AchievementDefinition[],
): AchievementTickResult {
  if (state.meta.tickCount % 10 !== 0) {
    return { achievements: state.achievements, newAchievements: [] };
  }

  const unlockedIds = new Set(state.achievements.unlocked.map(a => a.id));
  const newAchievements: string[] = [];
  const unlocked = [...state.achievements.unlocked];

  for (const def of definitions) {
    if (unlockedIds.has(def.id)) continue;
    if (checkCondition(state, def)) {
      unlocked.push({ id: def.id, unlockedAtTick: state.meta.tickCount });
      newAchievements.push(def.name);
    }
  }

  return {
    achievements: { ...state.achievements, unlocked },
    newAchievements,
  };
}