/* B03 파일 입력 페이지 */

import {
  CURRENT_PROJECT_ID_KEY,
  UPLOAD_ALLOWED_EXT,
  UPLOAD_MAX_FILES,
  UPLOAD_MAX_MB,
} from "@config/config_frontend";
import { currentLanguageIndex, ui_locales } from "@ui/ui_template_locale";
import {
  createButton,
  createCard,
  hideLoadingOverlay,
  showLoadingOverlay,
  showToast,
} from "@ui/ui_template_elements";
import { uploadProjectFiles, type UploadedFileResult } from "./B03_FileInput_Api_Fetch";
import "./B03_FileInput_UI_Style.css";

function L(key: keyof typeof ui_locales): string {
  return ui_locales[key][currentLanguageIndex];
}

function validateFiles(files: readonly File[]): string | null {
  if (files.length === 0) return L("B03_File_Error_Required");
  if (files.length > UPLOAD_MAX_FILES) return L("B03_File_Error_Count");

  const maximumBytes = UPLOAD_MAX_MB * 1024 * 1024;
  const normalizedNames = new Set<string>();
  let lasCount = 0;
  for (const file of files) {
    const extensionIndex = file.name.lastIndexOf(".");
    const extension = extensionIndex >= 0 ? file.name.slice(extensionIndex).toLowerCase() : "";
    if (!UPLOAD_ALLOWED_EXT.includes(extension as (typeof UPLOAD_ALLOWED_EXT)[number])) {
      return `${L("B03_File_Error_Extension")} ${file.name}`;
    }
    if (file.size === 0 || file.size > maximumBytes) {
      return `${L("B03_File_Error_Size")} ${file.name}`;
    }
    const normalizedName = file.name.toLocaleLowerCase();
    if (normalizedNames.has(normalizedName)) return `${L("B03_File_Error_Extension")} ${file.name}`;
    normalizedNames.add(normalizedName);
    if (extension === ".las" || extension === ".laz") lasCount += 1;
  }
  return lasCount === 1 ? null : L("B03_File_Error_Las");
}

export function renderB03FileInput(root: HTMLElement): void {
  let selectedFiles: File[] = [];
  const page = document.createElement("div");
  page.className = "b03-file";

  const header = document.createElement("div");
  header.className = "b03-file__header";
  const title = document.createElement("h1");
  title.className = "b03-file__title";
  title.textContent = L("B03_File_Title");
  const subtitle = document.createElement("p");
  subtitle.className = "b03-file__subtitle";
  subtitle.textContent = L("B03_File_Subtitle");
  header.append(title, subtitle);

  const fileInput = document.createElement("input");
  fileInput.type = "file";
  fileInput.multiple = true;
  fileInput.accept = UPLOAD_ALLOWED_EXT.join(",");
  fileInput.className = "b03-file__native-input";

  const dropzone = document.createElement("div");
  dropzone.className = "b03-file__dropzone";
  dropzone.tabIndex = 0;
  const dropzoneLabel = document.createElement("strong");
  dropzoneLabel.textContent = L("B03_File_Select_Label");
  const dropzoneHint = document.createElement("span");
  dropzoneHint.textContent = L("B03_File_Select_Hint");
  dropzone.append(dropzoneLabel, dropzoneHint, fileInput);

  const errorSlot = document.createElement("p");
  errorSlot.className = "b03-file__error";
  errorSlot.setAttribute("role", "alert");
  const selectedTitle = document.createElement("h2");
  selectedTitle.className = "b03-file__section-title";
  selectedTitle.textContent = L("B03_File_Selected_Title");
  const selectedList = document.createElement("ul");
  selectedList.className = "b03-file__list";
  const resultList = document.createElement("ul");
  resultList.className = "b03-file__results";

  function renderSelectedFiles(): void {
    selectedList.replaceChildren();
    if (selectedFiles.length === 0) {
      const empty = document.createElement("li");
      empty.className = "b03-file__empty";
      empty.textContent = L("B03_File_Selected_Empty");
      selectedList.append(empty);
      return;
    }
    for (const file of selectedFiles) {
      const item = document.createElement("li");
      const name = document.createElement("span");
      name.textContent = file.name;
      const size = document.createElement("span");
      size.textContent = `${(file.size / (1024 * 1024)).toFixed(2)} MB`;
      item.append(name, size);
      selectedList.append(item);
    }
  }

  function setSelectedFiles(files: readonly File[]): void {
    selectedFiles = Array.from(files);
    errorSlot.textContent = validateFiles(selectedFiles) ?? "";
    renderSelectedFiles();
  }

  function renderUploadResults(results: readonly UploadedFileResult[]): void {
    resultList.replaceChildren();
    for (const result of results) {
      const item = document.createElement("li");
      const filename = document.createElement("strong");
      filename.textContent = result.original_filename;
      const path = document.createElement("span");
      path.textContent = `${L("B03_File_Result_Path")}: ${result.relative_path}`;
      item.append(filename, path);
      resultList.append(item);
    }
  }

  function onB03_File_Select_Change(): void {
    setSelectedFiles(fileInput.files ? Array.from(fileInput.files) : []);
  }

  function onB03_File_Drop(event: DragEvent): void {
    event.preventDefault();
    dropzone.classList.remove("is-dragging");
    setSelectedFiles(event.dataTransfer?.files ? Array.from(event.dataTransfer.files) : []);
  }

  async function onB03_File_Upload_Click(): Promise<void> {
    const projectId = localStorage.getItem(CURRENT_PROJECT_ID_KEY);
    const validationError = validateFiles(selectedFiles);
    if (!projectId) {
      errorSlot.textContent = L("B03_File_Error_Project");
      return;
    }
    if (validationError) {
      errorSlot.textContent = validationError;
      return;
    }

    errorSlot.textContent = "";
    showLoadingOverlay();
    try {
      const response = await uploadProjectFiles(projectId, selectedFiles);
      renderUploadResults(response.files);
      showToast(L("B03_File_Upload_Success"), "success");
    } catch (error) {
      const detail = error instanceof Error ? error.message : L("B03_File_Upload_Failed");
      errorSlot.textContent = `${L("B03_File_Upload_Failed")} ${detail}`;
      showToast(L("B03_File_Upload_Failed"), "error");
    } finally {
      hideLoadingOverlay();
    }
  }

  fileInput.addEventListener("change", onB03_File_Select_Change);
  dropzone.addEventListener("click", () => fileInput.click());
  dropzone.addEventListener("keydown", (event) => {
    if (event.key === "Enter" || event.key === " ") fileInput.click();
  });
  dropzone.addEventListener("dragover", (event) => {
    event.preventDefault();
    dropzone.classList.add("is-dragging");
  });
  dropzone.addEventListener("dragleave", () => dropzone.classList.remove("is-dragging"));
  dropzone.addEventListener("drop", onB03_File_Drop);

  const uploadButton = createButton({
    label: L("B03_File_Upload_Button"),
    variant: "filled",
    onClick: () => void onB03_File_Upload_Click(),
  });
  const body = document.createElement("div");
  body.className = "b03-file__body";
  body.append(dropzone, errorSlot, selectedTitle, selectedList, uploadButton, resultList);
  page.append(header, createCard({ body: [body], raised: true }));
  root.replaceChildren(page);
  renderSelectedFiles();
}