document.addEventListener("DOMContentLoaded", () => {
  const moduleEl = document.querySelector("[data-import-module]");
  if (!moduleEl) return;

  const dropzone = moduleEl.querySelector("[data-import-dropzone]");
  const input = dropzone?.querySelector("input[type='file']");
  const uploadButton = moduleEl.querySelector("[data-import-upload-trigger]");
  const resetButton = moduleEl.querySelector("[data-import-reset]");
  const feedbackEl = moduleEl.querySelector("#import-upload-feedback");
  const previewBody = moduleEl.querySelector("[data-import-preview-body]");
  const previewContainer = moduleEl.querySelector("#import-preview-container");
  const actionsEl = moduleEl.querySelector("[data-import-actions]");
  const commitButton = moduleEl.querySelector("[data-import-commit]");
  const cancelButton = moduleEl.querySelector("[data-import-cancel]");

  let stageToken = null;

  function showFeedback(message, type = "info") {
    if (!feedbackEl) return;
    feedbackEl.textContent = message;
    feedbackEl.classList.remove("hidden", "success", "error", "info");
    feedbackEl.classList.add(type);
  }

  function hideFeedback() {
    if (!feedbackEl) return;
    feedbackEl.textContent = "";
    feedbackEl.classList.add("hidden");
  }

  function clearPreview() {
    if (previewBody) {
      previewBody.innerHTML = "";
    }
    previewContainer?.classList.add("hidden");
    actionsEl?.classList.add("hidden");
    commitButton?.setAttribute("disabled", "disabled");
    stageToken = null;
  }

  function enableUpload() {
    uploadButton?.removeAttribute("disabled");
    resetButton?.classList.remove("hidden");
  }

  function disableUpload() {
    uploadButton?.setAttribute("disabled", "disabled");
    uploadButton?.classList.remove("loading");
    resetButton?.classList.add("hidden");
  }

  dropzone?.addEventListener("dragover", (event) => {
    event.preventDefault();
    dropzone.classList.add("dragover");
  });

  dropzone?.addEventListener("dragleave", () => {
    dropzone.classList.remove("dragover");
  });

  dropzone?.addEventListener("drop", (event) => {
    event.preventDefault();
    dropzone.classList.remove("dragover");
    if (!event.dataTransfer?.files?.length || !input) {
      return;
    }
    input.files = event.dataTransfer.files;
    enableUpload();
    hideFeedback();
  });

  input?.addEventListener("change", () => {
    if (input.files?.length) {
      enableUpload();
      hideFeedback();
    } else {
      disableUpload();
    }
  });

  resetButton?.addEventListener("click", () => {
    if (input) {
      input.value = "";
    }
    disableUpload();
    hideFeedback();
    clearPreview();
  });

  async function uploadAndPreview() {
    if (!input?.files?.length) {
      showFeedback(
        "Please select a CSV or XLSX file before uploading.",
        "error"
      );
      return;
    }

    const file = input.files[0];
    showFeedback("Uploading…", "info");
    uploadButton?.classList.add("loading");
    uploadButton?.setAttribute("disabled", "disabled");

    const formData = new FormData();
    formData.append("file", file);

    let response;
    try {
      response = await fetch("/imports/projects/preview", {
        method: "POST",
        body: formData,
      });
    } catch (error) {
      console.error(error);
      NotificationCenter?.show({
        message: "Network error during upload.",
        level: "error",
      });
      showFeedback("Network error during upload.", "error");
      uploadButton?.classList.remove("loading");
      uploadButton?.removeAttribute("disabled");
      return;
    }

    if (!response.ok) {
      const detail = await response.json().catch(() => ({}));
      const message = detail?.detail || "Upload failed. Please check the file.";
      NotificationCenter?.show({ message, level: "error" });
      showFeedback(message, "error");
      uploadButton?.classList.remove("loading");
      uploadButton?.removeAttribute("disabled");
      return;
    }

    const payload = await response.json();
    hideFeedback();
    renderPreview(payload);
    uploadButton?.classList.remove("loading");
    uploadButton?.removeAttribute("disabled");

    NotificationCenter?.show({
      message: `Preview ready: ${payload.summary.accepted} row(s) accepted`,
      level: "success",
    });
  }

  function renderPreview(payload) {
    const rows = payload.rows || [];
    const issues = payload.row_issues || [];
    stageToken = payload.stage_token || null;

    if (!previewBody) return;
    previewBody.innerHTML = "";

    const issueMap = new Map();
    issues.forEach((issue) => {
      issueMap.set(issue.row_number, issue.issues);
    });

    rows.forEach((row) => {
      const tr = document.createElement("tr");
      const rowIssues = issueMap.get(row.row_number) || [];
      const issuesText = [
        ...row.issues,
        ...rowIssues.map((i) => i.message),
      ].join(", ");

      tr.innerHTML = `
        <td>${row.row_number}</td>
        <td><span class="badge badge--${row.state}">${row.state}</span></td>
        <td>${issuesText || "—"}</td>
        ${Object.values(row.data)
          .map((value) => `<td>${value ?? ""}</td>`)
          .join("")}
      `;
      previewBody.appendChild(tr);
    });

    previewContainer?.classList.remove("hidden");
    if (stageToken && payload.summary.accepted > 0) {
      actionsEl?.classList.remove("hidden");
      commitButton?.removeAttribute("disabled");
    } else {
      actionsEl?.classList.add("hidden");
      commitButton?.setAttribute("disabled", "disabled");
    }
  }

  uploadButton?.addEventListener("click", uploadAndPreview);

  commitButton?.addEventListener("click", async () => {
    if (!stageToken) return;
    commitButton.classList.add("loading");
    commitButton.setAttribute("disabled", "disabled");

    let response;
    try {
      response = await fetch("/imports/projects/commit", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ token: stageToken }),
      });
    } catch (error) {
      console.error(error);
      NotificationCenter?.show({
        message: "Network error during commit.",
        level: "error",
      });
      commitButton.classList.remove("loading");
      commitButton.removeAttribute("disabled");
      return;
    }

    if (!response.ok) {
      const detail = await response.json().catch(() => ({}));
      const message =
        detail?.detail || "Commit failed. Please review the import data.";
      NotificationCenter?.show({ message, level: "error" });
      commitButton.classList.remove("loading");
      commitButton.removeAttribute("disabled");
      return;
    }

    const result = await response.json();
    NotificationCenter?.show({
      message: `Import committed. Created: ${result.summary.created}, Updated: ${result.summary.updated}`,
      level: "success",
    });
    clearPreview();
    if (input) {
      input.value = "";
    }
    disableUpload();
  });

  cancelButton?.addEventListener("click", () => {
    clearPreview();
    NotificationCenter?.show({ message: "Import canceled.", level: "info" });
  });
});