import type { GameState, InfrastructureState, DataCenter, RackOrder, Rack, PipelineStage } 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,
} 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 stageTotal(stage: PipelineStage, order: RackOrder): number {
  const sku = RACK_SKU_CONFIGS[order.skuId];
  const timings = sku.pipelineTimeTicks;
  switch (stage) {
    case 'manufacturing': return timings.manufacturing;
    case 'receiving': return timings.receiving;
    case 'installation': return timings.installation;
    case 'testing': return timings.testing;
    case 'repair': return RACK_REPAIR_BASE_TICKS;
    case 'decommission': return timings.installation;
    default: return 0;
  }
}

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;
  }
}

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;

  // --- Phase 1: Advance DC Construction ---
  const dataCenters: DataCenter[] = state.infrastructure.dataCenters.map(dc => {
    if (dc.status !== 'constructing') return { ...dc };

    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 };
  });

  // --- Phase 2: Advance Rack Pipeline ---
  const rackPipeline: RackOrder[] = [];
  const newRacks: Rack[] = [];

  for (const order of state.infrastructure.rackPipeline) {
    const speed = stageSpeed(order.stage, engEff, opsEff);
    const newProgress = order.stageProgress + speed;

    if (newProgress < order.stageTotal) {
      rackPipeline.push({ ...order, stageProgress: newProgress });
      continue;
    }

    if (order.stage === 'decommission') {
      const sku = RACK_SKU_CONFIGS[order.skuId];
      notifications.push({
        title: 'Rack Decommissioned',
        message: `${sku.name} rack has been fully decommissioned.`,
        type: 'info',
      });
      continue;
    }

    if (order.stage === 'repair') {
      const total = stageTotal('testing', order);
      rackPipeline.push({
        ...order,
        stage: 'testing',
        stageProgress: 0,
        stageTotal: total,
      });
      continue;
    }

    const next = nextStage(order.stage);

    if (next === 'production') {
      const sku = RACK_SKU_CONFIGS[order.skuId];
      const dc = dataCenters.find(d => d.id === order.dataCenterId);
      const cooling = dc?.coolingLevel ?? 0;

      const effectiveFailRate = sku.testFailureRate
        * (1 - cooling * COOLING_FAILURE_REDUCTION)
        * (1 - opsEff * 0.2)
        * (1 - qaResearchBonus);

      if (Math.random() < effectiveFailRate) {
        const repairCost = sku.baseCost * sku.repairCostFraction;
        repairCosts += repairCost;
        rackPipeline.push({
          ...order,
          stage: 'repair',
          stageProgress: 0,
          stageTotal: RACK_REPAIR_BASE_TICKS,
          repairCount: order.repairCount + 1,
        });
        notifications.push({
          title: 'Rack Failed Testing',
          message: `${sku.name} rack failed QA (attempt ${order.repairCount + 1}). Repair cost: $${repairCost.toLocaleString()}`,
          type: 'warning',
        });
      } else {
        newRacks.push({
          id: order.id,
          skuId: order.skuId,
          dataCenterId: order.dataCenterId,
          isHealthy: true,
        });
        notifications.push({
          title: 'Rack Online',
          message: `${sku.name} rack is now in production at ${dc?.name ?? 'data center'}.`,
          type: 'success',
        });
      }
    } else {
      const total = stageTotal(next, order);
      rackPipeline.push({
        ...order,
        stage: next,
        stageProgress: 0,
        stageTotal: total,
      });
    }
  }

  // Add newly completed racks to their data centers
  for (const rack of newRacks) {
    const dcIdx = dataCenters.findIndex(d => d.id === rack.dataCenterId);
    if (dcIdx !== -1) {
      dataCenters[dcIdx] = {
        ...dataCenters[dcIdx],
        racks: [...dataCenters[dcIdx].racks, rack],
      };
    }
  }

  // --- Phase 3: Production Failures ---
  for (let dcIdx = 0; dcIdx < dataCenters.length; dcIdx++) {
    const dc = dataCenters[dcIdx];
    if (dc.status !== 'operational') continue;

    const updatedRacks: Rack[] = [];
    for (const rack of dc.racks) {
      if (!rack.isHealthy) {
        updatedRacks.push(rack);
        continue;
      }

      const sku = RACK_SKU_CONFIGS[rack.skuId];
      const effectiveRate = sku.productionFailureRate
        * (1 - dc.coolingLevel * COOLING_FAILURE_REDUCTION)
        * (1 - dc.redundancyLevel * REDUNDANCY_FAILURE_REDUCTION);

      if (Math.random() < effectiveRate) {
        updatedRacks.push({ ...rack, isHealthy: false });
        const repairCost = sku.baseCost * sku.repairCostFraction;
        repairCosts += repairCost;

        rackPipeline.push({
          id: rack.id,
          skuId: rack.skuId,
          dataCenterId: dc.id,
          stage: 'repair',
          stageProgress: 0,
          stageTotal: RACK_REPAIR_BASE_TICKS,
          totalCost: repairCost,
          repairCount: 0,
        });

        notifications.push({
          title: 'Rack Failure',
          message: `${sku.name} rack failed in ${dc.name}. Sent for repair.`,
          type: 'danger',
        });
      } else {
        updatedRacks.push(rack);
      }
    }

    // Remove failed racks from the DC (they're now in the repair pipeline)
    dataCenters[dcIdx] = {
      ...dc,
      racks: updatedRacks.filter(r => r.isHealthy),
    };
  }

  // --- Phase 4: Compute Aggregates ---
  let totalFlops = 0;
  let totalUptime = 0;
  let totalRackCount = 0;
  let dcWithRacks = 0;

  for (let dcIdx = 0; dcIdx < dataCenters.length; dcIdx++) {
    const dc = dataCenters[dcIdx];
    if (dc.status !== 'operational') continue;

    const location = LOCATION_CONFIGS[dc.location];
    const tierConfig = DC_TIER_CONFIGS[dc.tier];

    let dcFlops = 0;
    let usedPowerKW = 0;
    const healthyCount = dc.racks.length;
    const totalInDc = dc.racks.length;

    for (const rack of dc.racks) {
      const sku = RACK_SKU_CONFIGS[rack.skuId];
      dcFlops += sku.flopsPerRack;
      usedPowerKW += sku.powerDrawKW;
    }

    const pipelineRacksForDc = rackPipeline.filter(o => o.dataCenterId === dc.id && o.stage !== 'decommission').length;
    const usedSlots = totalInDc + pipelineRacksForDc;

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

    const currentUptime = totalInDc > 0 ? healthyCount / totalInDc : 1;

    totalFlops += dcFlops;
    totalRackCount += totalInDc;
    if (totalInDc > 0) {
      totalUptime += currentUptime;
      dcWithRacks++;
    }

    dataCenters[dcIdx] = {
      ...dataCenters[dcIdx],
      usedSlots,
      usedPowerKW,
      energyCostPerTick,
      maintenanceCostPerTick,
      currentUptime,
    };
  }

  return {
    infrastructure: {
      dataCenters,
      rackPipeline,
      totalFlops,
      totalUptime: dcWithRacks > 0 ? totalUptime / dcWithRacks : 1,
      totalRackCount,
    },
    notifications,
    repairCosts,
  };
}