import type {
  GameState, InfrastructureState, Cluster, Campus, DataCenter,
  DeploymentCohort, NetworkHealthState, PipelineStage, RackSkuId,
  CampusRetrofitQueue,
} from '@ai-tycoon/shared';
import {
  LOCATION_CONFIGS,
  RACK_SKU_CONFIGS,
  DC_TIER_CONFIGS,
  BASE_ENERGY_COST_PER_FLOP,
  BASE_MAINTENANCE_PER_RACK,
  COOLING_FAILURE_REDUCTION,
  REDUNDANCY_FAILURE_REDUCTION,
  RACK_REPAIR_BASE_TICKS,
  NETWORK_TOPOLOGY,
  COHORT_SCALE_FACTOR,
  PIPELINE_ORDER_BASE_TICKS,
  networkSlotsRequired,
} from '@ai-tycoon/shared';
import type { TickNotification } from '../tick';

export interface InfraTickResult {
  infrastructure: InfrastructureState;
  notifications: TickNotification[];
  repairCosts: number;
}

const PIPELINE_ADVANCE_ORDER: PipelineStage[] = [
  'ordered', 'manufacturing', 'receiving', 'installation', 'testing',
];

function nextStage(stage: PipelineStage): PipelineStage | 'production' {
  const idx = PIPELINE_ADVANCE_ORDER.indexOf(stage);
  if (idx === -1 || idx === PIPELINE_ADVANCE_ORDER.length - 1) return 'production';
  return PIPELINE_ADVANCE_ORDER[idx + 1];
}

function cohortStageTotal(stage: PipelineStage, skuId: string, count: number): number {
  const sku = RACK_SKU_CONFIGS[skuId as keyof typeof RACK_SKU_CONFIGS];
  const timings = sku.pipelineTimeTicks;
  let base: number;
  switch (stage) {
    case 'ordered': base = PIPELINE_ORDER_BASE_TICKS; break;
    case 'manufacturing': base = timings.manufacturing; break;
    case 'receiving': base = timings.receiving; break;
    case 'installation': base = timings.installation; break;
    case 'testing': base = timings.testing; break;
    case 'repair': base = RACK_REPAIR_BASE_TICKS; break;
    case 'decommission': base = timings.installation; break;
    default: base = 0;
  }
  return Math.ceil(base * (1 + COHORT_SCALE_FACTOR * count));
}

function stageSpeed(stage: PipelineStage, engEff: number, opsEff: number): number {
  switch (stage) {
    case 'manufacturing': return 1 + engEff * 0.1;
    case 'installation':
    case 'testing':
    case 'decommission': return 1 + opsEff * 0.1;
    case 'repair': return 1 + opsEff * 0.05;
    default: return 1;
  }
}

function binomialSample(n: number, p: number): number {
  if (n <= 0 || p <= 0) return 0;
  if (p >= 1) return n;
  const expected = n * p;
  const base = Math.floor(expected);
  const frac = expected - base;
  return base + (Math.random() < frac ? 1 : 0);
}

function computeNetworkHealth(computeRacksOnline: number): NetworkHealthState {
  if (computeRacksOnline <= 0) {
    return { tier1Required: 0, tier1Healthy: 0, tier2Required: 0, tier2Healthy: 0, tier3Required: 0, tier3Healthy: 0, racksDisconnected: 0 };
  }
  const tier1 = Math.ceil(computeRacksOnline / NETWORK_TOPOLOGY.tier1PerCompute);
  const tier2 = Math.ceil(tier1 / NETWORK_TOPOLOGY.tier2PerTier1);
  const tier3 = NETWORK_TOPOLOGY.tier3PerDC;
  return {
    tier1Required: tier1,
    tier1Healthy: tier1,
    tier2Required: tier2,
    tier2Healthy: tier2,
    tier3Required: tier3,
    tier3Healthy: tier3,
    racksDisconnected: 0,
  };
}

function processNetworkFailures(
  nh: NetworkHealthState,
  computeRacksOnline: number,
  networkResearchBonus: number,
): { networkHealth: NetworkHealthState; racksDisconnected: number } {
  if (computeRacksOnline <= 0) {
    return { networkHealth: nh, racksDisconnected: 0 };
  }

  let racksDisconnected = 0;

  const t1Rate = NETWORK_TOPOLOGY.tier1FailureRate * (1 - networkResearchBonus);
  const t1Failures = binomialSample(nh.tier1Required, t1Rate);
  const tier1Healthy = nh.tier1Required - t1Failures;
  racksDisconnected += t1Failures * NETWORK_TOPOLOGY.tier1BlastRadius;

  const t2Rate = NETWORK_TOPOLOGY.tier2FailureRate * (1 - networkResearchBonus);
  const t2Failures = binomialSample(nh.tier2Required, t2Rate);
  const tier2Healthy = nh.tier2Required - t2Failures;
  racksDisconnected += t2Failures * NETWORK_TOPOLOGY.tier1BlastRadius * NETWORK_TOPOLOGY.tier2BlastRadiusMultiplier;

  const t3Rate = NETWORK_TOPOLOGY.tier3FailureRate * (1 - networkResearchBonus);
  const t3Failures = binomialSample(nh.tier3Required, t3Rate);
  const tier3Healthy = nh.tier3Required - t3Failures;
  if (t3Failures > 0) {
    racksDisconnected = computeRacksOnline;
  }

  racksDisconnected = Math.min(racksDisconnected, computeRacksOnline);

  return {
    networkHealth: {
      ...nh,
      tier1Healthy,
      tier2Healthy,
      tier3Healthy,
      racksDisconnected,
    },
    racksDisconnected,
  };
}

export function processInfrastructure(state: GameState): InfraTickResult {
  const notifications: TickNotification[] = [];
  let repairCosts = 0;

  const engEff = state.talent.departments.engineering.effectiveness;
  const opsEff = state.talent.departments.operations.effectiveness;
  const qaResearchBonus = state.research.completedResearch.includes('quality-assurance') ? 0.25 : 0;
  const netResearch1 = state.research.completedResearch.includes('network-engineering-i') ? 0.4 : 0;
  const netResearch2 = state.research.completedResearch.includes('network-engineering-ii') ? 0.5 : 0;
  const networkResearchBonus = Math.min(0.8, netResearch1 + netResearch2);

  let totalFlops = 0;
  let totalUptime = 0;
  let totalRackCount = 0;
  let totalComputeRackCount = 0;
  let totalDataCenterCount = 0;
  let dcWithRacks = 0;

  const clusters: Cluster[] = state.infrastructure.clusters.map(cluster => {
    // Advance cluster construction
    if (cluster.status === 'constructing') {
      const newProgress = cluster.constructionProgress + 1;
      if (newProgress >= cluster.constructionTotal) {
        notifications.push({
          title: 'Cluster Online',
          message: `${cluster.name} cluster in ${LOCATION_CONFIGS[cluster.locationId].name} is now operational!`,
          type: 'success',
        });
        return { ...cluster, constructionProgress: cluster.constructionTotal, status: 'operational' as const, campuses: cluster.campuses };
      }
      return { ...cluster, constructionProgress: newProgress };
    }

    const campuses: Campus[] = cluster.campuses.map(campus => {
      // Advance campus construction
      if (campus.status === 'constructing') {
        const newProgress = campus.constructionProgress + 1;
        if (newProgress >= campus.constructionTotal) {
          notifications.push({
            title: 'Campus Ready',
            message: `Campus ${campus.name} is now operational!`,
            type: 'success',
          });
          return { ...campus, constructionProgress: campus.constructionTotal, status: 'operational' as const, dataCenters: campus.dataCenters };
        }
        return { ...campus, constructionProgress: newProgress };
      }

      const dataCenters: DataCenter[] = campus.dataCenters.map(dc => {
        // Advance DC construction
        if (dc.status === 'constructing') {
          const newProgress = dc.constructionProgress + 1;
          if (newProgress >= dc.constructionTotal) {
            notifications.push({
              title: 'Data Center Online',
              message: `${dc.name} is now operational!`,
              type: 'success',
            });
            return { ...dc, constructionProgress: dc.constructionTotal, status: 'operational' as const };
          }
          return { ...dc, constructionProgress: newProgress };
        }

        let computeRacksOnline = dc.computeRacksOnline;
        let dcRepairCosts = 0;

        // Process retrofit
        if (dc.status === 'retrofitting' && dc.retrofitState) {
          const rs = { ...dc.retrofitState };
          rs.progress += (1 + opsEff * 0.1);

          if (rs.progress >= rs.total) {
            if (rs.phase === 'decommissioning') {
              const installSku = RACK_SKU_CONFIGS[rs.toSkuId];
              const installTotal = cohortStageTotal('installation', rs.toSkuId, rs.racksRemaining);
              return {
                ...dc,
                computeRacksOnline: 0,
                computeRacksFailed: 0,
                rackSkuId: rs.toSkuId,
                deploymentCohorts: [{
                  id: `retrofit-${dc.id}-${Date.now()}`,
                  count: rs.racksRemaining,
                  skuId: rs.toSkuId,
                  stage: 'installation' as PipelineStage,
                  stageProgress: 0,
                  stageTotal: installTotal,
                  repairCount: 0,
                }],
                retrofitState: {
                  ...rs,
                  phase: 'installing' as const,
                  progress: 0,
                  total: installTotal,
                },
                networkHealth: computeNetworkHealth(0),
                effectiveComputeRacks: 0,
                usedSlots: 0,
                usedPowerKW: 0,
                currentUptime: 0,
                energyCostPerTick: DC_TIER_CONFIGS[dc.tier].baseEnergyCostPerTick * LOCATION_CONFIGS[cluster.locationId].energyCostMultiplier,
                maintenanceCostPerTick: 0,
              };
            } else {
              notifications.push({
                title: 'Retrofit Complete',
                message: `${dc.name} retrofit to ${RACK_SKU_CONFIGS[rs.toSkuId].name} is complete!`,
                type: 'success',
              });
              return {
                ...dc,
                status: 'operational' as const,
                retrofitState: null,
              };
            }
          }
          return { ...dc, retrofitState: rs };
        }

        // Process deployment cohorts
        const updatedCohorts: DeploymentCohort[] = [];
        let racksJustOnlined = 0;
        let racksFailedTesting = 0;

        for (const cohort of dc.deploymentCohorts) {
          const speed = stageSpeed(cohort.stage, engEff, opsEff);
          const newProgress = cohort.stageProgress + speed;

          if (newProgress < cohort.stageTotal) {
            updatedCohorts.push({ ...cohort, stageProgress: newProgress });
            continue;
          }

          if (cohort.stage === 'decommission') {
            continue;
          }

          if (cohort.stage === 'repair') {
            const testTotal = cohortStageTotal('testing', cohort.skuId, cohort.count);
            updatedCohorts.push({
              ...cohort,
              stage: 'testing',
              stageProgress: 0,
              stageTotal: testTotal,
            });
            continue;
          }

          const next = nextStage(cohort.stage);

          if (next === 'production') {
            const sku = RACK_SKU_CONFIGS[cohort.skuId];
            const effectiveFailRate = sku.testFailureRate
              * (1 - dc.coolingLevel * COOLING_FAILURE_REDUCTION)
              * (1 - opsEff * 0.2)
              * (1 - qaResearchBonus);

            const failed = binomialSample(cohort.count, effectiveFailRate);
            const passed = cohort.count - failed;

            racksJustOnlined += passed;

            if (failed > 0) {
              racksFailedTesting += failed;
              const repairCost = sku.baseCost * sku.repairCostFraction * failed;
              dcRepairCosts += repairCost;

              updatedCohorts.push({
                id: `repair-${cohort.id}`,
                count: failed,
                skuId: cohort.skuId,
                stage: 'repair',
                stageProgress: 0,
                stageTotal: cohortStageTotal('repair', cohort.skuId, failed),
                repairCount: cohort.repairCount + 1,
              });
            }
          } else {
            const total = cohortStageTotal(next, cohort.skuId, cohort.count);
            updatedCohorts.push({
              ...cohort,
              stage: next,
              stageProgress: 0,
              stageTotal: total,
            });
          }
        }

        computeRacksOnline += racksJustOnlined;

        if (racksFailedTesting > 0) {
          const skuName = dc.rackSkuId ? RACK_SKU_CONFIGS[dc.rackSkuId].name : 'Unknown';
          notifications.push({
            title: 'Racks Failed Testing',
            message: `${dc.name}: ${racksFailedTesting} ${skuName} rack${racksFailedTesting > 1 ? 's' : ''} failed QA — repair batch created.`,
            type: 'warning',
          });
        }

        if (racksJustOnlined > 0 && updatedCohorts.filter(c => c.stage !== 'repair').length === 0) {
          notifications.push({
            title: 'Deployment Complete',
            message: `${dc.name}: all racks deployed and online!`,
            type: 'success',
          });
        }

        // Production failures (statistical)
        if (computeRacksOnline > 0 && dc.rackSkuId) {
          const sku = RACK_SKU_CONFIGS[dc.rackSkuId];
          const effectiveRate = sku.productionFailureRate
            * (1 - dc.coolingLevel * COOLING_FAILURE_REDUCTION)
            * (1 - dc.redundancyLevel * REDUNDANCY_FAILURE_REDUCTION);

          const prodFailures = binomialSample(computeRacksOnline, effectiveRate);
          if (prodFailures > 0) {
            computeRacksOnline -= prodFailures;
            const repairCost = sku.baseCost * sku.repairCostFraction * prodFailures;
            dcRepairCosts += repairCost;

            updatedCohorts.push({
              id: `prodfail-${dc.id}-${Date.now()}`,
              count: prodFailures,
              skuId: dc.rackSkuId,
              stage: 'repair',
              stageProgress: 0,
              stageTotal: cohortStageTotal('repair', dc.rackSkuId, prodFailures),
              repairCount: 0,
            });


          }
        }

        repairCosts += dcRepairCosts;

        // Network health
        const baseNetworkHealth = computeNetworkHealth(computeRacksOnline);
        const { networkHealth, racksDisconnected } = processNetworkFailures(
          baseNetworkHealth, computeRacksOnline, networkResearchBonus,
        );

        if (racksDisconnected > 0) {
          if (networkHealth.tier3Healthy < networkHealth.tier3Required) {
            notifications.push({
              title: 'Core Network Failure',
              message: `${dc.name}: Tier-3 core switch failure — entire DC disconnected!`,
              type: 'danger',
            });
          } else if (racksDisconnected >= NETWORK_TOPOLOGY.tier1BlastRadius * NETWORK_TOPOLOGY.tier2BlastRadiusMultiplier) {
            notifications.push({
              title: 'Network Switch Failure',
              message: `${dc.name}: Tier-2 aggregation failure — ${racksDisconnected} racks disconnected.`,
              type: 'warning',
            });
          }
        }

        const effectiveComputeRacks = computeRacksOnline - racksDisconnected;

        // Compute aggregates for this DC
        const location = LOCATION_CONFIGS[cluster.locationId];
        const tierConfig = DC_TIER_CONFIGS[dc.tier];
        const pipelineRacks = updatedCohorts
          .filter(c => c.stage !== 'decommission')
          .reduce((sum, c) => sum + c.count, 0);
        const computeRacksFailed = updatedCohorts
          .filter(c => c.stage === 'repair')
          .reduce((sum, c) => sum + c.count, 0);
        const totalRacksInDc = computeRacksOnline + pipelineRacks;
        const netSlots = networkSlotsRequired(computeRacksOnline + pipelineRacks);
        const usedSlots = computeRacksOnline + pipelineRacks + netSlots;

        let usedPowerKW = 0;
        let dcFlops = 0;
        if (dc.rackSkuId && computeRacksOnline > 0) {
          const sku = RACK_SKU_CONFIGS[dc.rackSkuId];
          usedPowerKW = computeRacksOnline * sku.powerDrawKW;
          dcFlops = effectiveComputeRacks * sku.flopsPerRack;
        }

        const energyCostPerTick = (tierConfig.baseEnergyCostPerTick + usedPowerKW * BASE_ENERGY_COST_PER_FLOP)
          * location.energyCostMultiplier;
        const maintenanceCostPerTick = totalRacksInDc * BASE_MAINTENANCE_PER_RACK;

        const currentUptime = totalRacksInDc > 0 ? effectiveComputeRacks / totalRacksInDc : 1;

        totalFlops += dcFlops;
        totalRackCount += totalRacksInDc + netSlots;
        totalComputeRackCount += totalRacksInDc;
        totalDataCenterCount++;
        if (totalRacksInDc > 0) {
          totalUptime += currentUptime;
          dcWithRacks++;
        }

        return {
          ...dc,
          computeRacksOnline,
          computeRacksFailed,
          deploymentCohorts: updatedCohorts,
          networkHealth,
          effectiveComputeRacks,
          usedSlots,
          usedPowerKW,
          energyCostPerTick,
          maintenanceCostPerTick,
          currentUptime,
        };
      });

      // Process campus retrofit queue
      let finalDCs = dataCenters;
      let updatedQueue: CampusRetrofitQueue | null = campus.retrofitQueue ?? null;

      if (updatedQueue && updatedQueue.pendingDCIds.length + updatedQueue.activeDCIds.length > 0) {
        updatedQueue = { ...updatedQueue };

        // Detect DCs that just completed retrofit (were active, now operational)
        const newlyCompleted = finalDCs.filter(
          dc => updatedQueue!.activeDCIds.includes(dc.id) && dc.status === 'operational',
        );

        if (newlyCompleted.length > 0) {
          updatedQueue.activeDCIds = updatedQueue.activeDCIds.filter(
            id => !newlyCompleted.some(dc => dc.id === id),
          );
          updatedQueue.completedDCIds = [
            ...updatedQueue.completedDCIds,
            ...newlyCompleted.map(dc => dc.id),
          ];
        }

        // Promote DCs from pending to active
        const slotsAvailable = updatedQueue.maxConcurrent - updatedQueue.activeDCIds.length;
        if (slotsAvailable > 0 && updatedQueue.pendingDCIds.length > 0) {
          const toStart = updatedQueue.pendingDCIds.slice(0, slotsAvailable);
          updatedQueue.pendingDCIds = updatedQueue.pendingDCIds.slice(toStart.length);
          updatedQueue.activeDCIds = [...updatedQueue.activeDCIds, ...toStart];

          finalDCs = finalDCs.map(dc => {
            if (!toStart.includes(dc.id)) return dc;
            if (dc.status !== 'operational' || !dc.rackSkuId) return dc;

            const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
            const totalRacks = dc.computeRacksOnline + pipelineCount;
            if (totalRacks <= 0) return dc;

            const oldSku = RACK_SKU_CONFIGS[dc.rackSkuId as RackSkuId];
            const decommTicks = Math.ceil(oldSku.pipelineTimeTicks.installation * (1 + COHORT_SCALE_FACTOR * totalRacks));

            return {
              ...dc,
              status: 'retrofitting' as const,
              deploymentCohorts: [],
              retrofitState: {
                fromSkuId: dc.rackSkuId as RackSkuId,
                toSkuId: updatedQueue!.targetSkuId,
                phase: 'decommissioning' as const,
                progress: 0,
                total: decommTicks,
                racksRemaining: totalRacks,
              },
            };
          });
        }

        // Check if queue is complete
        if (updatedQueue.pendingDCIds.length === 0 && updatedQueue.activeDCIds.length === 0) {
          notifications.push({
            title: 'Campus Retrofit Complete',
            message: `All DCs in ${campus.name} have been retrofitted to ${RACK_SKU_CONFIGS[updatedQueue.targetSkuId].name}!`,
            type: 'success',
          });
          updatedQueue = null;
        }
      }

      return { ...campus, dataCenters: finalDCs, retrofitQueue: updatedQueue };
    });

    return { ...cluster, campuses };
  });

  return {
    infrastructure: {
      clusters,
      totalFlops,
      totalUptime: dcWithRacks > 0 ? totalUptime / dcWithRacks : 1,
      totalRackCount,
      totalComputeRackCount,
      totalDataCenterCount,
    },
    notifications,
    repairCosts,
  };
}