import parser from "./parser.js";
import { compileProgram } from "./compiler.js";

const SAMPLE_PROGRAM = `// THIS PROGRAM COMPUTES X1 + X2

// Y <- X1
[ A1 ] IF X1 != 0 GOTO A2
       GOTO B1
[ A2 ] X1 <- X1 - 1
       Y <- Y + 1
       GOTO A1

// Z1 <- X2
[ B1 ] IF X2 != 0 GOTO B2
       GOTO C1
[ B2 ] X2 <- X2 - 1
       Z1 <- Z1 + 1
       GOTO B1

// Y <- Y + Z1
[ C1 ] IF Z1 != 0 GOTO C2
       GOTO E1
[ C2 ] Z1 <- Z1 - 1
       Y <- Y + 1
       GOTO C1`;

const STATUS_VARIANTS = {
  success: "text-success",
  error: "text-error",
  info: "muted"
};

export class GodelPlayground {
  constructor() {
    this.elements = {
      compileBtn: document.getElementById("compile-btn"),
      copyBtn: document.getElementById("copy-btn"),
      evalBtn: document.getElementById("eval-btn"),
      computeNumberBtn: document.getElementById("compute-godel-btn"),
      compileStatus: document.getElementById("compile-status"),
      evalStatus: document.getElementById("eval-status"),
      godelSequence: document.getElementById("godel-sequence"),
      godelNumber: document.getElementById("godel-number")
    };

    this.sourceEditor = null;
    this.compiledEditor = null;
    this.worker = null;
    this.latestSequence = [];

    this.init();
  }

  init() {
    this.setupEditors();
    this.bindEvents();
    this.hydrateFromParams();
    if (!this.getSource().trim()) {
      this.setSource(SAMPLE_PROGRAM);
    }
    this.compileSource();
  }

  setupEditors() {
    this.sourceEditor = adelieEditor.init("#source-editor", {
      language: "javascript"
    });
    this.compiledEditor = adelieEditor.init("#compiled-editor", {
      language: "javascript"
    });
    this.setSource(SAMPLE_PROGRAM);
  }

  bindEvents() {
    this.elements.compileBtn.addEventListener("click", () => this.compileSource());
    this.elements.evalBtn.addEventListener("click", () => this.evaluateCompiled());
    this.elements.copyBtn.addEventListener("click", () => this.copyShareLink());
    this.elements.computeNumberBtn.addEventListener("click", () => this.computeGodelNumber());

    document.addEventListener("keydown", (event) => {
      if (event.ctrlKey && event.key === "Enter") {
        event.preventDefault();
        this.compileSource();
      }
    });
  }

  hydrateFromParams() {
    const params = new URLSearchParams(window.location.search);
    const encoded = params.get("instructions");
    if (encoded) {
      try {
        const decoded = atob(encoded);
        this.setSource(decoded);
      } catch (error) {
        console.warn("Failed to decode instructions from URL", error);
      }
    }
  }

  getSource() {
    return this.sourceEditor.state.doc.toString();
  }

  setSource(content) {
    const docLength = this.sourceEditor.state.doc.toString().length;
    this.sourceEditor.dispatch({
      changes: { from: 0, to: docLength, insert: content }
    });
  }

  getCompiled() {
    return this.compiledEditor.state.doc.toString();
  }

  setCompiled(content) {
    const docLength = this.compiledEditor.state.doc.toString().length;
    this.compiledEditor.dispatch({
      changes: { from: 0, to: docLength, insert: content }
    });
  }

  prepareSource(source) {
    return source.replace(/\/\/.*$/gm, "").trim();
  }

  compileSource() {
    const raw = this.getSource();
    const prepared = this.prepareSource(raw);

    if (!prepared) {
      this.setStatus("compile", "Provide some source to compile", "error");
      return;
    }

    try {
      const ast = parser.parse(prepared);
      const { js, godelSequence } = compileProgram(ast);
      this.latestSequence = godelSequence;
      this.setCompiled(js);
      this.renderSequence(godelSequence);
      this.setStatus(
        "compile",
        `Compiled ${godelSequence.length} instruction${godelSequence.length === 1 ? "" : "s"}.`,
        "success"
      );
      this.elements.computeNumberBtn.disabled = godelSequence.length === 0;
    } catch (error) {
      this.latestSequence = [];
      this.renderSequence([]);
      this.elements.computeNumberBtn.disabled = true;
      this.setStatus("compile", error.message || "Failed to compile program", "error");
    }
  }

  evaluateCompiled() {
    const js = this.getCompiled();
    if (!js.trim()) {
      this.setStatus("eval", "Compile a program first", "error");
      return;
    }

    try {
      const result = (0, eval)(js);
      this.setStatus(
        "eval",
        `Result: ${typeof result === "undefined" ? "(no return)" : result}`,
        "success"
      );
    } catch (error) {
      this.setStatus("eval", error.message || "Failed to evaluate program", "error");
    }
  }

  renderSequence(sequence) {
    if (!sequence.length) {
      this.elements.godelSequence.textContent = "Compile to view the Gödel sequence.";
      this.elements.godelNumber.textContent = "";
      return;
    }
    this.elements.godelSequence.textContent = `[${sequence.join(", ")}]`;
    this.elements.godelNumber.textContent = "";
  }

  copyShareLink() {
    const data = btoa(this.getSource());
    const url = `${window.location.href.split("?")[0]}?instructions=${data}`;

    navigator.clipboard.writeText(url)
      .then(() => alert("Shareable link copied to clipboard"))
      .catch(() => alert("Failed to copy link"));
  }

  computeGodelNumber() {
    if (!this.latestSequence.length) {
      this.setStatus("compile", "Compile a program to produce its Gödel sequence", "error");
      return;
    }

    this.elements.godelNumber.textContent = "Working...";
    this.elements.computeNumberBtn.disabled = true;

    const worker = this.getWorker();
    worker.onmessage = (event) => {
      this.elements.godelNumber.textContent = event.data;
      this.elements.computeNumberBtn.disabled = false;
    };
    worker.onerror = () => {
      this.elements.godelNumber.textContent = "Failed to compute Gödel number";
      this.elements.computeNumberBtn.disabled = false;
    };
    worker.postMessage(this.latestSequence);
  }

  getWorker() {
    if (!this.worker) {
      const workerUrl = new URL("./godel-worker.js", import.meta.url);
      this.worker = new Worker(workerUrl, { type: "module" });
    }
    return this.worker;
  }

  setStatus(kind, message, variant = "info") {
    const element = kind === "compile" ? this.elements.compileStatus : this.elements.evalStatus;
    element.textContent = message;
    element.className = `status-text ${STATUS_VARIANTS[variant] || ""}`;
  }
}