import { api, describeError, onUnauthorized } from "./api.js";
import { element } from "./dom.js";
import { destinationSelect, setAutoExtractDefault, setupDownloadForm, updateSubfolderState } from "./download-form.js";
import { formatBytes } from "./format.js";
import { recentDestinations, renderHistory } from "./history.js";
import { isActive, matchesFilter, renderJobs, updateSpeeds } from "./jobs.js";
import { fillLibrarySelect } from "./libraries.js";
import { setupLogin } from "./login.js";
import { collectTransitions, notifyTransitions } from "./notify.js";
import { loadSettings, openSettings, setupSettings } from "./settings.js";
import { renderTree, topLevelSelection } from "./tree.js";

const pollIntervalMs = 1500;
const filterStorageKey = "ddc-job-filter";
const failuresBeforeBanner = 2;

const elements = {
  loginView: document.getElementById("login-view"),
  loginForm: document.getElementById("login-form"),
  loginError: document.getElementById("login-error"),
  appView: document.getElementById("app-view"),
  logoutButton: document.getElementById("logout-button"),
  settingsButton: document.getElementById("settings-button"),
  diskStatus: document.getElementById("disk-status"),
  connectionBanner: document.getElementById("connection-banner"),
  jobFilter: document.getElementById("job-filter"),
  clearCompletedButton: document.getElementById("clear-completed-button"),
  jobList: document.getElementById("job-list"),
  jobEmpty: document.getElementById("job-empty"),
  detail: document.getElementById("job-detail"),
  detailTitle: document.getElementById("detail-title"),
  closeDetailButton: document.getElementById("close-detail-button"),
  fileTree: document.getElementById("file-tree"),
  selectionSummary: document.getElementById("selection-summary"),
  librarySelect: document.getElementById("library-select"),
  subfolderInput: document.getElementById("subfolder-input"),
  cleanupCheckbox: document.getElementById("cleanup-checkbox"),
  moveButton: document.getElementById("move-button"),
  actionError: document.getElementById("action-error"),
  history: {
    title: document.getElementById("history-title"),
    list: document.getElementById("history-list"),
    empty: document.getElementById("history-empty"),
    clearButton: document.getElementById("clear-history-button"),
  },
};

const state = {
  jobs: [],
  destinations: [],
  downloadPaths: [],
  historyEntries: [],
  selectedJobId: null,
  treeStatus: null,
  selection: new Set(),
  pollTimer: null,
  refreshing: false,
  failedRefreshes: 0,
};

function showLogin() {
  stopPolling();
  setConnectionProblem(null);
  closeDetail();
  elements.appView.hidden = true;
  elements.loginView.hidden = false;
}

async function showApp() {
  elements.loginView.hidden = true;
  elements.appView.hidden = false;
  applyDefaults(await loadSettings());
  await Promise.all([loadLibraries(), loadHistory()]);
  await refresh();
  startPolling();
}

function applyDefaults(settings) {
  setAutoExtractDefault(settings.autoExtract);
  elements.cleanupCheckbox.checked = settings.cleanupAfterMove;
  state.downloadPaths = settings.downloadPaths || [];
  renderDestinationSelects();
}

async function showSettings() {
  try {
    await openSettings();
  } catch (error) {
    window.alert(describeError(error));
  }
}

function startPolling() {
  stopPolling();
  state.pollTimer = window.setInterval(refresh, pollIntervalMs);
}

function stopPolling() {
  if (state.pollTimer !== null) window.clearInterval(state.pollTimer);
  state.pollTimer = null;
}

async function loadLibraries() {
  state.destinations = (await api.libraries()) || [];
  renderDestinationSelects();
}

async function loadHistory() {
  try {
    state.historyEntries = (await api.history()) || [];
    renderHistory(elements.history, state.historyEntries);
    renderDestinationSelects();
  } catch (error) {
    if (error.status !== 401) console.error(error);
  }
}

function renderDestinationSelects() {
  const extras = { recentPaths: recentDestinations(state.historyEntries), savedPaths: state.downloadPaths };
  fillLibrarySelect(elements.librarySelect, state.destinations, extras);
  fillLibrarySelect(destinationSelect(), state.destinations, { ...extras, emptyLabel: "Temporary folder (move later)" });
  updateSubfolderState();
}

async function refresh() {
  if (state.refreshing) return;
  state.refreshing = true;
  try {
    const [jobs, disk] = await Promise.all([api.jobs(), api.disk()]);
    state.jobs = jobs || [];
    updateSpeeds(state.jobs);
    handleTransitions(collectTransitions(state.jobs));
    elements.diskStatus.textContent = `${formatBytes(disk.availableBytes)} free`;
    setConnectionProblem(null);
    renderJobList();
    await syncDetail();
  } catch (error) {
    if (error.status !== 401) {
      console.error(error);
      setConnectionProblem(error);
    }
  } finally {
    state.refreshing = false;
  }
}

function setConnectionProblem(error) {
  if (!error) {
    state.failedRefreshes = 0;
    elements.connectionBanner.hidden = true;
    return;
  }
  state.failedRefreshes += 1;
  if (state.failedRefreshes < failuresBeforeBanner) return;
  elements.connectionBanner.textContent = `${describeError(error)} Retrying automatically.`;
  elements.connectionBanner.hidden = false;
}

function handleTransitions(transitions) {
  notifyTransitions(transitions);
  if (transitions.some((transition) => transition.previous === "moving")) loadHistory();
  if (transitions.length > 0) {
    loadLibraries().catch((error) => console.error(error));
  }
}

function renderJobList() {
  const filter = elements.jobFilter.value;
  const visibleJobs = state.jobs.filter((job) => matchesFilter(job, filter));
  elements.jobEmpty.hidden = visibleJobs.length > 0;
  elements.jobEmpty.textContent = state.jobs.length === 0
    ? "No downloads yet. Paste a link above to start."
    : "No downloads match this filter.";
  elements.clearCompletedButton.hidden = !state.jobs.some((job) => job.status === "completed");
  renderJobs(elements.jobList, visibleJobs, state.selectedJobId, {
    onBrowse: openDetail,
    onPause: (job) => runJobAction(() => api.pause(job.id)),
    onResume: (job) => runJobAction(() => api.resume(job.id)),
    onReorder: (job, direction) => runJobAction(() => api.reorder(job.id, direction)),
    onDelete: deleteJob,
  });
}

async function runJobAction(action) {
  try {
    await action();
    await refresh();
  } catch (error) {
    window.alert(describeError(error));
  }
}

function selectedJob() {
  return state.jobs.find((job) => job.id === state.selectedJobId);
}

function openDetail(job) {
  state.selectedJobId = job.id;
  state.treeStatus = null;
  state.selection.clear();
  elements.actionError.textContent = "";
  elements.detail.hidden = false;
  renderJobList();
  syncDetail();
  loadLibraries().catch((error) => {
    elements.actionError.textContent = describeError(error);
  });
  elements.detail.scrollIntoView({ behavior: "smooth", block: "start" });
}

function closeDetail() {
  state.selectedJobId = null;
  state.treeStatus = null;
  state.selection.clear();
  elements.detail.hidden = true;
  elements.fileTree.replaceChildren();
}

async function syncDetail() {
  const job = selectedJob();
  if (!job) {
    if (state.selectedJobId) closeDetail();
    return;
  }

  elements.detailTitle.textContent = job.fileName;
  if (job.status === state.treeStatus) return;
  state.treeStatus = job.status;

  if (job.status === "ready") {
    await loadTree(job.id);
    return;
  }

  state.selection.clear();
  updateSelectionSummary();
  const text = job.status === "completed"
    ? "Files were moved and temporary files were removed."
    : "Files will be available when this download is ready.";
  elements.fileTree.replaceChildren(element("p", "muted", text));
}

async function loadTree(jobId) {
  try {
    const nodes = (await api.files(jobId)) || [];
    state.selection.clear();
    renderTree(elements.fileTree, nodes, state.selection, {
      onSelectionChange: updateSelectionSummary,
      onExtract: extractArchive,
    });
    updateSelectionSummary();
  } catch (error) {
    elements.actionError.textContent = describeError(error);
  }
}

function updateSelectionSummary() {
  const count = topLevelSelection(state.selection).length;
  const job = selectedJob();
  elements.selectionSummary.textContent = count === 0 ? "Nothing selected" : `${count} item(s) selected`;
  elements.moveButton.disabled = count === 0 || !job || job.status !== "ready";
}

async function extractArchive(path) {
  elements.actionError.textContent = "";
  try {
    await api.extract(state.selectedJobId, path);
    await refresh();
  } catch (error) {
    elements.actionError.textContent = describeError(error);
  }
}

async function moveSelection() {
  elements.actionError.textContent = "";
  const paths = topLevelSelection(state.selection);
  if (paths.length === 0) return;

  try {
    await api.move(state.selectedJobId, {
      paths,
      destination: elements.librarySelect.value,
      subfolder: elements.subfolderInput.value.trim(),
      cleanup: elements.cleanupCheckbox.checked,
    });
    elements.subfolderInput.value = "";
    await refresh();
  } catch (error) {
    elements.actionError.textContent = describeError(error);
  }
}

async function deleteJob(job) {
  const question = isActive(job)
    ? `Cancel and remove "${job.fileName}"?`
    : `Remove "${job.fileName}" and its temporary files?`;
  if (!window.confirm(question)) return;

  try {
    await api.remove(job.id);
    if (job.id === state.selectedJobId) closeDetail();
    await refresh();
  } catch (error) {
    window.alert(describeError(error));
  }
}

async function clearCompleted() {
  const completedJobs = state.jobs.filter((job) => job.status === "completed");
  for (const job of completedJobs) {
    try {
      await api.remove(job.id);
      if (job.id === state.selectedJobId) closeDetail();
    } catch (error) {
      console.error(error);
    }
  }
  await refresh();
}

async function clearHistory() {
  if (!window.confirm("Clear the move history?")) return;
  try {
    await api.clearHistory();
    await loadHistory();
  } catch (error) {
    window.alert(describeError(error));
  }
}

function setupJobFilter() {
  try {
    const saved = localStorage.getItem(filterStorageKey);
    if (saved && [...elements.jobFilter.options].some((option) => option.value === saved)) {
      elements.jobFilter.value = saved;
    }
  } catch {
    elements.jobFilter.value = "all";
  }
  elements.jobFilter.addEventListener("change", () => {
    try {
      localStorage.setItem(filterStorageKey, elements.jobFilter.value);
    } catch {
      console.warn("Could not remember the download filter.");
    }
    renderJobList();
  });
}

async function logout() {
  try {
    await api.logout();
  } finally {
    showLogin();
  }
}

async function init() {
  window.addEventListener("unhandledrejection", (event) => console.error("Unhandled error", event.reason));
  onUnauthorized(showLogin);
  setupLogin(elements.loginForm, elements.loginError, showApp);
  setupDownloadForm(refresh);
  setupJobFilter();
  elements.clearCompletedButton.addEventListener("click", clearCompleted);
  elements.history.clearButton.addEventListener("click", clearHistory);
  elements.moveButton.addEventListener("click", moveSelection);
  elements.closeDetailButton.addEventListener("click", () => {
    closeDetail();
    renderJobList();
  });
  elements.logoutButton.addEventListener("click", logout);
  elements.settingsButton.addEventListener("click", showSettings);
  setupSettings((settings) => {
    applyDefaults(settings);
    refresh();
  });

  try {
    const session = await api.session();
    if (session && session.authenticated) await showApp();
    else showLogin();
  } catch {
    showLogin();
  }
}

init();