import { computeMachineStats } from "./stats";
import type { MachineSetup, CalculatedTimings } from "./types";
import type { Recipe } from "../../scripts/factorio-dump/helpers/recipes.helper";

export enum ContainerType {
  Chest = "Chest",
  Belt = "Belt",
  Splitter = "Splitter",
  Machine = "Machine",
}
export interface IContainer {
  readonly type: ContainerType;

  // For Inserter checking if it should wake up
  canAccept(itemId: string): boolean;
  getAvailable(itemId: string): number;

  // For Inserter executing the transfer
  insert(itemId: string, amount: number): void;
  extract(itemId: string, maxAmount: number): number;

  // Optional tick method for active containers (Machines)
  tick?(): void;
}

export const INSERTER_TIMINGS = {
  ROTATION: 3,
  PICKUP_RATE: {
    [ContainerType.Chest]: Infinity, // Grabs full hand instantly
    [ContainerType.Machine]: Infinity, // Grabs full hand instantly
    [ContainerType.Belt]: 4, // Grabs 4 items per tick
    [ContainerType.Splitter]: 4, // Grabs 4 items per tick
  },
  DROP_DELAY: {
    [ContainerType.Chest]: 1,
    [ContainerType.Machine]: 1,
    [ContainerType.Splitter]: 4,
    [ContainerType.Belt]: 5,
  },
};

export enum InserterState {
  Idle,
  Picking,
  SwingingForward,
  Dropping,
  SwingingBack,
}

export class MachineSimulator implements IContainer {
  public readonly type = ContainerType.Machine;
  public inputBuffer: Record<string, number> = {};
  public outputBuffer: Record<string, number> = {};

  public craftProgress = 0;
  public prodProgress = 0;
  public isCrafting = false;

  public timings: CalculatedTimings;
  private progressPerTick: number;

  private solidIngredients: { name: string; amount: number }[] = [];
  private solidResults: { name: string; amount: number }[] = [];

  private overloadLimits: Record<string, number> = {};
  private outputBlockLimits: Record<string, number> = {};

  constructor(
    public setup: MachineSetup,
    public recipe: Recipe,
    itemStackSizes: Record<string, number> = {},
  ) {
    this.timings = computeMachineStats(setup, recipe);
    this.progressPerTick = 1 / this.timings.singleCraftTicks;

    const ingredients = recipe.ingredients || [];
    for (const ing of ingredients) {
      if (ing.type === "item") {
        this.solidIngredients.push({ name: ing.name, amount: ing.amount });
        this.overloadLimits[ing.name] = ing.amount * this.timings.overloadMultiplier;
        this.inputBuffer[ing.name] = 0;
      }
    }

    const results = recipe.results || [];
    const hasIngredients = this.solidIngredients.length > 0;
    for (const res of results) {
      if (res.type === "item") {
        const amount = (res as any).amount ?? (res as any).amount_min ?? 1;
        this.solidResults.push({ name: res.name, amount });
        this.outputBuffer[res.name] = 0;

        const maxStack = itemStackSizes[res.name] ?? 50;
        this.outputBlockLimits[res.name] = hasIngredients
          ? Math.min(maxStack, this.timings.overloadMultiplier * amount)
          : maxStack;
      }
    }
  }

  public tick() {
    let progressRemaining = this.progressPerTick;

    while (progressRemaining > 0) {
      if (!this.isCrafting) {
        if (this.hasEnoughInputs() && !this.isOutputBlocked()) {
          this.consumeInputs();
          this.isCrafting = true;
        } else {
          break;
        }
      }

      if (this.isCrafting) {
        const progressToNextFinish = 1.0 - this.craftProgress;
        const step = Math.min(progressRemaining, progressToNextFinish);

        this.craftProgress += step;
        progressRemaining -= step;
        this.prodProgress += step * this.timings.productivityBonus;

        if (this.craftProgress >= 0.99999) {
          this.addResults(1);
          this.craftProgress = 0;
          this.isCrafting = false;
        }

        while (this.prodProgress >= 0.99999) {
          this.addResults(1);
          this.prodProgress -= 1.0;
        }
      }
    }
  }

  private hasEnoughInputs(): boolean {
    for (const ing of this.solidIngredients) {
      if (this.inputBuffer[ing.name] < ing.amount) return false;
    }
    return true;
  }

  private isOutputBlocked(): boolean {
    for (const res of this.solidResults) {
      if (this.outputBuffer[res.name] >= this.outputBlockLimits[res.name]) return true;
    }
    return false;
  }

  private consumeInputs() {
    for (const ing of this.solidIngredients) {
      this.inputBuffer[ing.name] -= ing.amount;
    }
  }

  private addResults(multiplier: number) {
    for (const res of this.solidResults) {
      this.outputBuffer[res.name] += res.amount * multiplier;
    }
  }

  public canAccept(itemId: string): boolean {
    const limit = this.overloadLimits[itemId];
    if (limit === undefined) return false; // Doesn't accept this item

    return this.inputBuffer[itemId] < limit && !this.isOutputBlocked();
  }
  public insert(itemId: string, amount: number): void {
    this.inputBuffer[itemId] = (this.inputBuffer[itemId] || 0) + amount;
  }

  public getAvailable(itemId: string): number {
    return this.outputBuffer[itemId] || 0;
  }
  public extract(itemId: string, maxAmount: number): number {
    const available = this.getAvailable(itemId);
    const toPick = Math.min(maxAmount, available);
    this.outputBuffer[itemId] -= toPick;
    return toPick;
  }
}
export class Chest implements IContainer {
  public readonly type = ContainerType.Chest;
  public receivedCounts: Record<string, number> = {};
  public extractedCounts: Record<string, number> = {};

  private readonly isSink: boolean;
  constructor(public providedItem?: string) {
    this.isSink = this.providedItem === undefined;
  }

  public canAccept(itemId: string): boolean {
    // Only accepts items if it wasn't configured as a source
    return this.isSink;
  }

  public getAvailable(itemId: string): number {
    return this.providedItem === itemId ? Infinity : 0;
  }

  public extract(itemId: string, maxAmount: number): number {
    if (this.getAvailable(itemId)) {
      this.extractedCounts[itemId] = (this.extractedCounts[itemId] || 0) + maxAmount;
      return maxAmount;
    }
    return 0;
  }

  public insert(itemId: string, amount: number): void {
    if (this.canAccept(itemId)) {
      this.receivedCounts[itemId] = (this.receivedCounts[itemId] || 0) + amount;
    }
  }
}

export class Belt implements IContainer {
  public readonly type = ContainerType.Belt;
  public receivedCounts: Record<string, number> = {};
  public extractedCounts: Record<string, number> = {};

  private readonly isSink: boolean;
  private readonly providedItems = new Set<string>();

  constructor(providedItem1?: string, providedItem2?: string) {
    this.isSink = providedItem1 === undefined && providedItem2 === undefined;

    if (providedItem1) this.providedItems.add(providedItem1);
    if (providedItem2) this.providedItems.add(providedItem2);
  }

  public canAccept(itemId: string): boolean {
    return this.isSink;
  }

  public getAvailable(itemId: string): number {
    return this.providedItems.has(itemId) ? Infinity : 0;
  }

  public extract(itemId: string, maxAmount: number): number {
    if (this.getAvailable(itemId)) {
      const amount = Math.min(maxAmount, 4);
      this.extractedCounts[itemId] = (this.extractedCounts[itemId] || 0) + amount;
      return amount;
    }
    return 0;
  }

  public insert(itemId: string, amount: number): void {
    if (this.canAccept(itemId)) {
      this.receivedCounts[itemId] = (this.receivedCounts[itemId] || 0) + amount;
    }
  }
}
export class InserterSimulator {
  public state: InserterState = InserterState.Idle;
  public ticksInState = 0;
  public heldItems = 0;

  public swingCount = 0;

  public isActive = true;

  public currentTargetItem: string;

  private readonly pickupRate: number;
  private readonly dropTicks: number;

  protected needed: number;
  protected toPick: number;

  constructor(
    public handSize: number,
    public source: IContainer,
    public destination: IContainer,
    public targetItemId: string,
  ) {
    this.currentTargetItem = targetItemId;
    this.pickupRate = INSERTER_TIMINGS.PICKUP_RATE[source.type];
    this.dropTicks = INSERTER_TIMINGS.DROP_DELAY[destination.type];
    this.needed = 0;
    this.toPick = 0;
  }

  public tick() {
    if (this.state === InserterState.Idle) {
      if (this.canWakeUp()) {
        this.state = InserterState.Picking;
        this.ticksInState = 0;

        // Initialize caches
        this.needed = this.handSize;
        this.toPick = Math.min(this.needed, this.pickupRate);
      } else {
        return;
      }
    }

    this.ticksInState++;

    switch (this.state) {
      case InserterState.Picking:
        if (this.isActive && this.toPick > 0) {
          const picked = this.source.extract(this.targetItemId, this.toPick);

          if (picked > 0) {
            this.heldItems += picked;
            this.needed -= picked;
            this.toPick = Math.min(this.needed, this.pickupRate);
          }
        }

        if (!this.needed) {
          this.state = InserterState.SwingingForward;
          this.ticksInState = 0;
        }
        break;

      case InserterState.SwingingForward:
        if (this.ticksInState >= INSERTER_TIMINGS.ROTATION) {
          this.state = InserterState.Dropping;
          this.ticksInState = 0;
        }
        break;

      case InserterState.Dropping:
        if (!this.destination.canAccept(this.targetItemId)) {
          this.ticksInState--;
          break;
        }

        if (this.ticksInState >= this.dropTicks) {
          this.destination.insert(this.targetItemId, this.heldItems);

          this.heldItems = 0;
          this.swingCount++;
          this.state = InserterState.SwingingBack;
          this.ticksInState = 0;
        }
        break;

      case InserterState.SwingingBack:
        if (this.ticksInState >= INSERTER_TIMINGS.ROTATION) {
          this.state = InserterState.Idle;
          this.ticksInState = 0;
        }
        break;
    }
  }

  protected canWakeUp(): boolean {
    return (
      this.isActive && this.source.getAvailable(this.targetItemId) > 0 && this.destination.canAccept(this.targetItemId)
    );
  }
}

export class FilterableInserterSimulator extends InserterSimulator {
  public staticFilters: string[] = [];

  public useDynamicFilters = false;
  public dynamicFilters: string[] = [];

  constructor(handSize: number, source: IContainer, destination: IContainer, filters: string[] = []) {
    // Pass the first filter as a dummy fallback to super()
    super(handSize, source, destination, filters[0] || "");
    this.staticFilters = filters;
  }

  // Called by the Circuit Network (Pub/Sub)
  public updateDynamicFilters(filters: string[]) {
    this.dynamicFilters = filters;

    // FACTORIO RULE: Partial Hand Eviction on Filter Change
    if (this.state === InserterState.Picking && this.useDynamicFilters) {
      if (!this.dynamicFilters.includes(this.currentTargetItem)) {
        if (this.heldItems > 0) {
          // Force it to swing forward with the partial hand
          this.needed = 0;
          this.toPick = 0;
        } else {
          // If empty, abort the pick and return to Idle
          this.state = InserterState.Idle;
          this.ticksInState = 0;
        }
      }
    }
  }

  protected override canWakeUp(): boolean {
    if (!this.isActive) return false;

    const activeFilters = this.useDynamicFilters ? this.dynamicFilters : this.staticFilters;

    // Scan the filters in order of priority (left to right in Factorio UI)
    for (const itemId of activeFilters) {
      if (this.source.getAvailable(itemId) > 0 && this.destination.canAccept(itemId)) {
        this.currentTargetItem = itemId;
        return true;
      }
    }

    return false;
  }
}

export class OptimizedClockRow {
  public rowId: string;
  public isActive = false;

  // Maps exact local tick -> target active state (true/false)
  private transitionMap = new Map<number, boolean>();
  private subscribers: ((isActive: boolean) => void)[] = [];

  constructor(
    rowId: string,
    blocks: { start: number; end: number }[],
    public cycleDuration: number,
  ) {
    this.rowId = rowId;

    // 1. Compile blocks into a temporary bitmap of length cycleDuration
    const bitmap = new Uint8Array(cycleDuration);
    for (const b of blocks) {
      let t = b.start;
      const end = b.end;
      while (t < end) {
        bitmap[t % cycleDuration] = 1;
        t++;
      }
    }

    // 2. Extract exact transition points where state changes
    for (let t = 0; t < cycleDuration; t++) {
      const prev = bitmap[(t - 1 + cycleDuration) % cycleDuration];
      const curr = bitmap[t];
      if (curr !== prev) {
        this.transitionMap.set(t, curr === 1);
      }
    }

    // Set initial state based on tick 0
    this.isActive = bitmap[0] === 1;
  }

  /**
   * Inserters subscribe to receive direct state change callbacks.
   */
  public subscribe(callback: (isActive: boolean) => void) {
    this.subscribers.push(callback);
    // Push initial state immediately upon subscription
    callback(this.isActive);
  }

  public tick(globalTick: number) {
    const localTick = globalTick % this.cycleDuration;

    // O(1) Check: Is this specific tick a transition boundary?
    if (this.transitionMap.has(localTick)) {
      const newState = this.transitionMap.get(localTick)!;

      // STATE CHANGE: Only trigger mutations when the boolean actually flips!
      if (newState !== this.isActive) {
        this.isActive = newState;

        for (const callback of this.subscribers) {
          callback(this.isActive);
        }
      }
    }
  }
}

export class SimulationOrchestrator {
  private tickables: { tick?(): void }[] = [];
  public currentTick = 0;

  /**
   * Add entities in strict topological order to mimic perfect Factorio build order.
   * e.g., Sources -> Input Inserters -> Machines -> Output Inserters -> Sinks
   */
  public register(entity: { tick?(): void }) {
    this.tickables.push(entity);
  }

  public tick() {
    for (const entity of this.tickables) {
      if (entity.tick) entity.tick();
    }
    this.currentTick++;
  }

  public tickUntil(condition: () => boolean, maxTicks = 10000): boolean {
    while (!condition() && this.currentTick < maxTicks) {
      this.tick();
    }
    return this.currentTick < maxTicks; // Returns true if condition met, false if timed out
  }
}
export class FactorioEngineOrchestrator {
  public currentTick = 0;

  // Entity Managers (Strict Execution Order!)
  private rows = new Map<string, OptimizedClockRow>();
  private belts: IContainer[] = [];
  private inserters: InserterSimulator[] = [];
  private machines: MachineSimulator[] = [];

  public registerBelt(belt: IContainer) {
    this.belts.push(belt);
  }
  public registerMachine(machine: MachineSimulator) {
    this.machines.push(machine);
  }

  public registerInserter(inserter: InserterSimulator) {
    this.inserters.push(inserter);
  }
  public registerRow(rowId: string, blocks: { start: number; end: number }[], cycleDuration: number) {
    const row = new OptimizedClockRow(rowId, blocks, cycleDuration);
    this.rows.set(rowId, row);
  }

  public bindInserterToRow(inserter: InserterSimulator, rowId: string) {
    const row = this.rows.get(rowId);
    if (!row) throw new Error(`Row ${rowId} not found in orchestrator`);

    // Pub/Sub binding: Inserter's isActive updates *only* when the row signals a state change
    row.subscribe((active) => {
      inserter.isActive = active;
    });
  }

  public tick() {
    // --- CLOCK & NETWORK STATE UPDATES ---
    for (const row of this.rows.values()) {
      row.tick(this.currentTick);
    }
    // Belts
    for (const belt of this.belts) {
      if (belt.tick) belt.tick();
    }
    // Inserters
    const sleepingOrHoveringInserters: InserterSimulator[] = [];
    const successfullyPickedInserters: InserterSimulator[] = [];

    for (const inserter of this.inserters) {
      const heldBefore = inserter.heldItems;

      inserter.tick();

      const pickedItemsThisTick = inserter.heldItems > heldBefore;

      if (pickedItemsThisTick) {
        // It got items, so it yields priority for the next tick
        successfullyPickedInserters.push(inserter);
      } else {
        // It got nothing (starved), so it maintains its priority at the front of the line
        sleepingOrHoveringInserters.push(inserter);
      }
    }

    this.inserters = [...sleepingOrHoveringInserters, ...successfullyPickedInserters];

    // Assemblers
    for (const machine of this.machines) {
      machine.tick();
    }

    this.currentTick++;
  }

  public tickUntil(condition: () => boolean, maxTicks = 10000): boolean {
    while (!condition() && this.currentTick < maxTicks) {
      this.tick();
    }
    return this.currentTick < maxTicks;
  }
}