(() => {
  const formSelector = "form[data-submit-once]";
  const pickerSelector = "[data-image-picker]";
  const allowedImageTypes = new Set(["image/jpeg", "image/png", "image/webp"]);
  const maxImageBytes = 5 * 1024 * 1024;
  const pickerStates = new WeakMap();

  function progressIndicator() {
    return document.getElementById("submit-progress");
  }

  function resetForm(form) {
    form.removeAttribute("aria-busy");
    delete form.dataset.submitting;

    const button = form.querySelector("[data-submit-button]");
    if (!button) {
      return;
    }
    button.disabled = false;
    button.removeAttribute("aria-disabled");
    if (button.dataset.idleLabel) {
      button.textContent = button.dataset.idleLabel;
      delete button.dataset.idleLabel;
    }
  }

  function existingImageCount(picker) {
    return picker.querySelectorAll("[data-existing-image]:not([hidden])").length;
  }

  function updateImageCount(picker, state) {
    const count = existingImageCount(picker) + state.entries.length;
    const status = picker.querySelector("[data-image-count]");
    if (status) {
      status.textContent = `${count} of ${state.max}`;
    }
  }

  function showImageError(picker, message) {
    const error = picker.querySelector("[data-image-error]");
    if (!error) {
      return;
    }
    error.textContent = message;
    error.hidden = !message;
  }

  function imageFileAllowed(file) {
    if (allowedImageTypes.has(file.type)) {
      return true;
    }
    if (file.type) {
      return false;
    }
    return /\.(jpe?g|png|webp)$/i.test(file.name);
  }

  function sameImageFile(left, right) {
    return left.name === right.name &&
      left.size === right.size &&
      left.lastModified === right.lastModified;
  }

  function syncImageInput(state) {
    const transfer = new DataTransfer();
    state.entries.forEach((entry) => transfer.items.add(entry.file));
    state.input.files = transfer.files;
  }

  function removeNewImage(picker, state, entry) {
    const index = state.entries.indexOf(entry);
    if (index === -1) {
      return;
    }
    state.entries.splice(index, 1);
    URL.revokeObjectURL(entry.previewURL);
    entry.card.remove();
    syncImageInput(state);
    showImageError(picker, "");
    updateImageCount(picker, state);
  }

  function addImageFiles(picker, state, files) {
    showImageError(picker, "");
    const uniqueFiles = files.filter((file) =>
      !state.entries.some((entry) => sameImageFile(entry.file, file))
    );
    const available = state.max - existingImageCount(picker) - state.entries.length;
    if (uniqueFiles.length > available) {
      showImageError(
        picker,
        available > 0
          ? `You can add ${available} more ${available === 1 ? "image" : "images"}.`
          : "You already have 4 images selected."
      );
      syncImageInput(state);
      return;
    }
    for (const file of uniqueFiles) {
      if (!imageFileAllowed(file)) {
        showImageError(picker, "Images must be JPEG, PNG, or WebP.");
        syncImageInput(state);
        return;
      }
      if (file.size > maxImageBytes) {
        showImageError(picker, `${file.name} is larger than 5 MB.`);
        syncImageInput(state);
        return;
      }
    }

    uniqueFiles.forEach((file) => {
      const fragment = state.template.content.cloneNode(true);
      const card = fragment.querySelector("[data-new-image]");
      const preview = fragment.querySelector("[data-image-preview]");
      const name = fragment.querySelector("[data-image-name]");
      const previewURL = URL.createObjectURL(file);
      preview.src = previewURL;
      if (name) {
        name.textContent = file.name;
      }
      const entry = { file, card, previewURL };
      const removeButton = card.querySelector("[data-remove-image]");
      removeButton.setAttribute("aria-label", `Remove selected image: ${file.name}`);
      removeButton.addEventListener("click", () => {
        removeNewImage(picker, state, entry);
      });
      state.list.appendChild(fragment);
      state.entries.push(entry);
    });
    syncImageInput(state);
    updateImageCount(picker, state);
  }

  function resetImagePicker(picker) {
    const state = pickerStates.get(picker);
    if (!state) {
      return;
    }
    state.entries.forEach((entry) => {
      URL.revokeObjectURL(entry.previewURL);
      entry.card.remove();
    });
    state.entries = [];
    state.input.value = "";
    picker.querySelectorAll("[data-existing-image]").forEach((card) => {
      card.hidden = false;
      card.querySelectorAll("input").forEach((input) => {
        input.disabled = false;
      });
    });
    showImageError(picker, "");
    updateImageCount(picker, state);
  }

  function initializeImagePicker(picker) {
    if (
      pickerStates.has(picker) ||
      typeof DataTransfer === "undefined" ||
      typeof URL.createObjectURL !== "function"
    ) {
      return;
    }
    const input = picker.querySelector("[data-image-input]");
    const dropzone = picker.querySelector("[data-image-dropzone]");
    const list = picker.querySelector("[data-image-list]");
    const template = picker.querySelector("[data-image-template]");
    if (!input || !dropzone || !list || !template) {
      return;
    }
    const state = {
      input,
      list,
      template,
      entries: [],
      max: Number.parseInt(picker.dataset.maxImages, 10) || 4,
    };
    pickerStates.set(picker, state);
    updateImageCount(picker, state);

    input.addEventListener("change", () => {
      addImageFiles(picker, state, Array.from(input.files));
    });
    picker.querySelectorAll("[data-existing-image]").forEach((card) => {
      card.querySelector("[data-remove-image]").addEventListener("click", () => {
        card.hidden = true;
        card.querySelectorAll("input").forEach((existingInput) => {
          existingInput.disabled = true;
        });
        showImageError(picker, "");
        updateImageCount(picker, state);
      });
    });
    ["dragenter", "dragover"].forEach((eventName) => {
      dropzone.addEventListener(eventName, (event) => {
        event.preventDefault();
        dropzone.classList.add("is-dragging");
      });
    });
    ["dragleave", "drop"].forEach((eventName) => {
      dropzone.addEventListener(eventName, (event) => {
        event.preventDefault();
        dropzone.classList.remove("is-dragging");
      });
    });
    dropzone.addEventListener("drop", (event) => {
      addImageFiles(picker, state, Array.from(event.dataTransfer.files));
    });
    picker.closest("form")?.addEventListener("reset", () => {
      window.setTimeout(() => resetImagePicker(picker), 0);
    });
  }

  document.addEventListener("submit", (event) => {
    const form = event.target.closest(formSelector);
    if (!form) {
      return;
    }
    if (form.dataset.submitting === "true") {
      event.preventDefault();
      return;
    }

    form.dataset.submitting = "true";
    form.setAttribute("aria-busy", "true");

    const button = event.submitter || form.querySelector("[data-submit-button]");
    if (button) {
      button.dataset.idleLabel = button.textContent;
      button.textContent = form.dataset.submittingLabel || "Posting…";
      button.disabled = true;
      button.setAttribute("aria-disabled", "true");
    }

    const progress = progressIndicator();
    if (progress) {
      progress.hidden = false;
    }
  });

  window.addEventListener("pageshow", () => {
    document.querySelectorAll(formSelector).forEach(resetForm);
    document.querySelectorAll(pickerSelector).forEach(resetImagePicker);
    const progress = progressIndicator();
    if (progress) {
      progress.hidden = true;
    }
  });

  document.querySelectorAll(pickerSelector).forEach(initializeImagePicker);
})();