// Native Chromium PDF viewer using a single persistent iframe.
// The iframe is created once in index.html and reused for all documents.

class NativePdfViewer {
  constructor(frame, container) {
    this.frame = frame;
    this.container = container;
    this.generation = 0;
    this.currentKey = null;
    this.lastUrl = null;
    this.loadTimer = null;
    this._onLoad = null;
    this._createDOM();
  }

  _createDOM() {
    this.loadingDiv = document.createElement("div");
    this.loadingDiv.className = "native-pdf-loading";
    this.loadingDiv.textContent = "Loading PDF\u2026";
    this.loadingDiv.hidden = true;
    this.container.appendChild(this.loadingDiv);

    this.errorDiv = document.createElement("div");
    this.errorDiv.className = "native-pdf-error";
    this.errorDiv.hidden = true;

    this.errorMsg = document.createElement("div");
    this.errorMsg.className = "native-pdf-error-msg";
    this.errorDiv.appendChild(this.errorMsg);

    this.retryBtn = document.createElement("button");
    this.retryBtn.className = "native-pdf-retry";
    this.retryBtn.textContent = "Retry";
    this.retryBtn.addEventListener("click", () => {
      if (this.lastUrl && this.currentKey) {
        this._navigate(this.lastUrl, this.currentKey, true);
      }
    });
    this.errorDiv.appendChild(this.retryBtn);
    this.container.appendChild(this.errorDiv);

    // Log iframe sizing once
    console.log(
      "[BizMatch QC] iframe size:",
      this.frame.clientWidth + "x" + this.frame.clientHeight,
      "container:",
      this.container.clientWidth + "x" + this.container.clientHeight,
    );
  }

  _showState(state) {
    this.loadingDiv.hidden = state !== "loading";
    this.errorDiv.hidden = state !== "error";
  }

  load(url, _byteSize, key) {
    this._navigate(url, key, false);
  }

  _navigate(url, key, force) {
    // Deduplicate only AFTER the key is accepted
    if (!force && key && key === this.currentKey) {
      return;
    }

    const generation = ++this.generation;
    this.currentKey = key;
    this.lastUrl = url;

    this._showState("loading");
    console.log(`[BizMatch QC] Native PDF src assigned: ${key}`);
    console.log(
      `[BizMatch QC] Native PDF iframe size: ${this.frame.clientWidth}x${this.frame.clientHeight}`,
    );

    // Register per-navigation load handler
    if (this._onLoad) {
      this.frame.removeEventListener("load", this._onLoad);
    }
    this._onLoad = () => {
      if (generation !== this.generation) return;
      if (this.loadTimer) {
        clearTimeout(this.loadTimer);
        this.loadTimer = null;
      }
      this._showState("loaded");
      console.log(`[BizMatch QC] Native PDF load event: ${key}`);
    };
    this.frame.addEventListener("load", this._onLoad, { once: true });

    // Safety timeout
    if (this.loadTimer) clearTimeout(this.loadTimer);
    this.loadTimer = setTimeout(() => {
      if (generation === this.generation) {
        console.warn(`[BizMatch QC] Native PDF load timeout: ${key}`);
        this._showState("error");
        this.errorMsg.textContent =
          "PDF load timed out. The file may be very large.";
      }
    }, 15000);

    this.frame.src = url;
  }

  destroy() {
    if (this.loadTimer) clearTimeout(this.loadTimer);
    if (this._onLoad) this.frame.removeEventListener("load", this._onLoad);
    this.generation = 0;
    this.frame.src = "";
    this._showState("loading");
  }
}

globalThis.NativePdfViewer = NativePdfViewer;