import { type Serve } from "bun";

// =================================================================
// 1. DOMAIN LAYER
// Simulates the core business entities and logic.
// =================================================================

export enum StepStatus {
  InProgress = "IN_PROGRESS",
  Completed = "COMPLETED",
  NotStarted = "NOT_STARTED"
}

export class Step {
  id: string;
  status: StepStatus;

  constructor(id: string, initialStatus: StepStatus = StepStatus.NotStarted) {
    this.id = id;
    this.status = initialStatus;
  }

  /**
   * In-memory repository to persist state.
   */
  private static repository = new Map<string, Step>();

  /**
   * Logic to find and return a Step instance by id
   * @param id
   * @returns
   */
  static find(id: string): Step | undefined {
    return this.repository.get(id);
  }

  /**
   * Logic to save a Step instance
   * @param step
   */
  static save(step: Step): void {
    this.repository.set(step.id, step);
  }

  static initializeWizard(): void {
    Step.save(new Step("step1", StepStatus.InProgress));
    Step.save(new Step("step2"));
    Step.save(new Step("step3"));
  }
}

// =================================================================
// 2. APPLICATION LAYER
// Contains the Application Controller and Command patterns.
// =================================================================

export type RequestParams = Record<string, any>;

export interface DomainCommand {
  run(params: RequestParams): void;
}

/**
 * Maps a command to its action and the *next* view.
 */
class CommandViewResponse {
  constructor(
    public readonly commandConstructor: new () => DomainCommand,
    public readonly nextView: string
  ) {}

  getDomainCommand(): DomainCommand {
    return new this.commandConstructor();
  }
}

/**
 * Completes step 1 and moves to step 2.
 * Only worries about the logic for its own step.
 * The Application Controller handles what comes next.
 */
class ProcessStep1Command implements DomainCommand {
  run(_params: RequestParams): void {
    console.log("   ACTION: Processing Step 1 submission.");
    const step1 = Step.find("step1")!;
    const step2 = Step.find("step2")!;
    step1.status = StepStatus.Completed;
    step2.status = StepStatus.InProgress;
  }
}

/**
 * Completes step 2 and moves to step 3,
 * or goes back to step 1 if "prev" is specified.
 * This command is more complex as it handles both directions.
 */
class ProcessStep2Command implements DomainCommand {
  run(params: RequestParams): void {
    console.log(`   ACTION: Processing Step 2 submission (Direction: ${params.direction}).`);
    const step1 = Step.find("step1")!;
    const step2 = Step.find("step2")!;
    const step3 = Step.find("step3")!;

    if (params.direction === "next") {
      step2.status = StepStatus.Completed;
      step3.status = StepStatus.InProgress;
    } else {
      // "prev"
      step2.status = StepStatus.NotStarted;
      step1.status = StepStatus.InProgress;
    }
  }
}

/**
 * The Application Controller.
 * It maps a command name (e.g., "submit-step1") directly to a command and a subsequent view.
 */
export class WizardApplicationController {
  private rules = new Map<string, CommandViewResponse>();

  constructor() {
    this.loadRules();
  }

  private loadRules(): void {
    // Command from Step 1 leads to Step 2 View
    this.rules.set("submit-step1", new CommandViewResponse(ProcessStep1Command, "step2View"));

    // Command from Step 2 ("next") leads to Step 3 View
    this.rules.set("submit-step2-next", new CommandViewResponse(ProcessStep2Command, "step3View"));

    // Command from Step 2 ("prev") leads to Step 1 View
    this.rules.set("submit-step2-prev", new CommandViewResponse(ProcessStep2Command, "step1View"));
  }

  private getResponse(commandString: string): CommandViewResponse {
    const response = this.rules.get(commandString);
    if (!response) {
      throw new Error(`No rule defined for command: ${commandString}`);
    }
    return response;
  }

  getDomainCommand(commandString: string): DomainCommand {
    return this.getResponse(commandString).getDomainCommand();
  }

  getView(commandString: string): string {
    return this.getResponse(commandString).nextView;
  }
}

// =================================================================
// 3. PRESENTATION LAYER
// =================================================================

// --- Setup ---
// Initialize the domain state
Step.initializeWizard();

// Instantiate the controller ONCE. This is the singleton.
const appController = new WizardApplicationController();

console.log("✅ Server started. Wizard is initialized.");
console.log("Try visiting:");
console.log("  - http://localhost:3000/submit-step1");
console.log("  - http://localhost:3000/submit-step2-next");
console.log("  - http://localhost:3000/submit-step2-prev");

export default {
  port: 3000,
  fetch(req) {
    const url = new URL(req.url);
    const command = url.pathname.substring(1); // Get command from path, e.g., "submit-step1"

    console.log(`\n\t\t➡️  Handling request for command: "${command}"`);

    try {
      const commandString = command;
      const params: RequestParams = {};

      // A simple way to distinguish between prev/next for step 2
      if (command.includes("next")) params.direction = "next";
      if (command.includes("prev")) params.direction = "prev";

      // 1. Get the domain command
      const domainCommand = appController.getDomainCommand(commandString);

      // 2. Run it
      domainCommand.run(params);

      // 3. Get the next view
      const viewPage = appController.getView(commandString);

      // 4. Respond
      const responseBody = `Successfully processed '${commandString}'.\nNext view: ${viewPage}.`;
      console.log(`   VIEW: Responding with next view: ${viewPage}`);
      return new Response(responseBody);
    } catch (error) {
      console.error("   ERROR:", error);
      return new Response("Invalid command or server error.", { status: 400 });
    }
  }
} satisfies Serve;