/**
 * history-tree.js — Дерево версий, свёртка групп, выбор и удаление
 */

import { apiFetch } from "./api.js";
import { getState, setCurrentVersionId, setHistoryVersions } from "./state.js";
import {
  formatHistoryDate,
  versionFileName,
  resetResult,
  updateDownloadCurrent,
  showSourcePreview,
  clearSourcePreview,
  setJobStatus,
} from "./ui.js";
import { rebuildReferenceSelect, clearReference, getReferenceState } from "./reference.js";
import { updateSuggestCodexButton } from "./suggest.js";

function historyItemBadge(version) {
  if (version.kind === "original") return "Исходник";
  if (version.kind === "upscale") return "Апскейл";
  return "Правка";
}

function buildChildrenMap(versions) {
  const map = new Map();
  for (const version of versions) {
    const key = version.parentId || "";
    if (!map.has(key)) {
      map.set(key, []);
    }
    map.get(key).push(version);
  }
  return map;
}

function countSubtreeSize(id, childrenMap) {
  let count = 1;
  const children = childrenMap.get(id);
  if (children) {
    for (const child of children) {
      count += countSubtreeSize(child.id, childrenMap);
    }
  }
  return count;
}

function renderTreeNode(version, depth, childrenMap, container) {
  const state = getState();
  const node = document.createElement("div");
  node.className = "history-node";
  node.style.setProperty("--depth", depth);

  if (version.id === state.currentVersionId) {
    node.classList.add("is-current");
  }

  const main = document.createElement("button");
  main.type = "button";
  main.className = "history-node-main";
  main.setAttribute("aria-label", version.label || "Версия");
  main.addEventListener("click", () => selectHistoryVersion(version));

  const thumb = document.createElement("img");
  thumb.className = "history-node-thumb";
  thumb.src = version.url;
  thumb.alt = "";
  thumb.loading = "lazy";

  const meta = document.createElement("span");
  meta.className = "history-node-meta";

  const title = document.createElement("strong");
  title.className = "history-node-title";
  title.textContent = version.label || "Версия";

  const badge = document.createElement("span");
  badge.className = "history-node-badge";
  badge.textContent = historyItemBadge(version);

  const date = document.createElement("span");
  date.className = "history-node-date";
  date.textContent = formatHistoryDate(version.createdAt);

  meta.append(title, badge, date);

  if (version.kind === "edit" && version.prompt) {
    const prompt = document.createElement("div");
    prompt.className = "history-node-prompt";
    prompt.textContent = version.prompt;
    prompt.title = version.prompt;
    meta.appendChild(prompt);
  }

  main.append(thumb, meta);

  const actions = document.createElement("div");
  actions.className = "history-node-actions";

  const download = document.createElement("a");
  download.className = "history-node-action history-download";
  download.href = version.url;
  download.download = versionFileName(version);
  download.textContent = "Скачать";
  download.addEventListener("click", (event) => event.stopPropagation());

  const remove = document.createElement("button");
  remove.type = "button";
  remove.className = "history-node-action history-delete";
  remove.textContent = "Удалить";
  remove.addEventListener("click", (event) => {
    event.stopPropagation();
    deleteVersion(version);
  });

  actions.append(download, remove);
  node.append(main, actions);

  if (childrenMap.has(version.id)) {
    const body = document.createElement("div");
    body.className = "history-node-children";
    for (const child of childrenMap.get(version.id)) {
      renderTreeNode(child, depth + 1, childrenMap, body);
    }
    node.appendChild(body);
  }

  container.appendChild(node);
}

export function renderHistory() {
  const list = document.querySelector("#history-list");
  const empty = document.querySelector("#history-empty");
  if (!list || !empty) return;

  const state = getState();
  const versions = state.historyVersions;

  list.querySelectorAll(".history-group").forEach((group) => group.remove());
  empty.hidden = versions.length > 0;

  const childrenMap = buildChildrenMap(versions);
  const roots = versions
    .filter(
      (version) =>
        version.kind === "original" ||
        !version.parentId ||
        !childrenMap.has(version.parentId)
    )
    .sort((a, b) => String(b.createdAt || "").localeCompare(String(a.createdAt || "")));

  rebuildReferenceSelect();

  for (const root of roots) {
    const group = document.createElement("div");
    group.className = "history-group";
    group.dataset.group = root.id;

    const rootNode = document.createElement("div");
    rootNode.className = "history-node is-root";
    rootNode.style.setProperty("--depth", 0);

    if (root.id === state.currentVersionId) {
      rootNode.classList.add("is-current");
    }

    const toggle = document.createElement("button");
    toggle.type = "button";
    toggle.className = "history-node-toggle";
    toggle.setAttribute("aria-label", "Свернуть ветку");
    const collapsed = state.collapsedGroups.has(root.id);
    toggle.setAttribute("aria-expanded", String(!collapsed));
    toggle.textContent = collapsed ? "▸" : "▾";
    toggle.addEventListener("click", (event) => {
      event.stopPropagation();
      if (state.collapsedGroups.has(root.id)) {
        state.collapsedGroups.delete(root.id);
      } else {
        state.collapsedGroups.set(root.id, true);
      }
      renderHistory();
    });

    const rootMain = document.createElement("button");
    rootMain.type = "button";
    rootMain.className = "history-node-main";
    rootMain.setAttribute("aria-label", root.label || "Версия");
    rootMain.addEventListener("click", () => selectHistoryVersion(root));

    const thumb = document.createElement("img");
    thumb.className = "history-node-thumb";
    thumb.src = root.url;
    thumb.alt = "";
    thumb.loading = "lazy";

    const meta = document.createElement("span");
    meta.className = "history-node-meta";

    const title = document.createElement("strong");
    title.className = "history-node-title";
    title.textContent = root.label || "Версия";

    const badge = document.createElement("span");
    badge.className = "history-node-badge";
    badge.textContent = historyItemBadge(root);

    const date = document.createElement("span");
    date.className = "history-node-date";
    date.textContent = formatHistoryDate(root.createdAt);

    meta.append(title, badge, date);

    if (root.kind === "edit" && root.prompt) {
      const prompt = document.createElement("div");
      prompt.className = "history-node-prompt";
      prompt.textContent = root.prompt;
      prompt.title = root.prompt;
      meta.appendChild(prompt);
    }

    rootMain.append(thumb, meta);

    const actions = document.createElement("div");
    actions.className = "history-node-actions";

    const download = document.createElement("a");
    download.className = "history-node-action history-download";
    download.href = root.url;
    download.download = versionFileName(root);
    download.textContent = "Скачать";
    download.addEventListener("click", (event) => event.stopPropagation());

    const remove = document.createElement("button");
    remove.type = "button";
    remove.className = "history-node-action history-delete";
    remove.textContent = "Удалить";
    remove.addEventListener("click", (event) => {
      event.stopPropagation();
      deleteVersion(root);
    });

    actions.append(download, remove);
    rootNode.append(toggle, rootMain, actions);
    group.appendChild(rootNode);

    const count = document.createElement("span");
    count.className = "history-group-count";
    const subtreeSize = countSubtreeSize(root.id, childrenMap);
    count.textContent = subtreeSize === 1 ? "1 версия" : `${subtreeSize} версий`;
    group.appendChild(count);

    if (!collapsed) {
      const body = document.createElement("div");
      body.className = "history-group-body";
      const children = childrenMap.get(root.id);
      if (children) {
        for (const child of children) {
          renderTreeNode(child, 1, childrenMap, body);
        }
      }
      group.appendChild(body);
    }

    list.appendChild(group);
  }
}

export function selectHistoryVersion(version) {
  const state = getState();
  if (state.isBusy) return;

  setCurrentVersionId(version.id);

  resetResult();
  updateDownloadCurrent(version);
  showSourcePreview(
    version.url,
    version.label || "Версия",
    version.width && version.height ? `${version.width}×${version.height}` : "Готово к обработке"
  );
  renderHistory();
  updateSuggestCodexButton();
  setJobStatus("idle", "");

  const editBtn = document.querySelector("#edit-button");
  const upscaleBtn = document.querySelector("#upscale-button");
  const promptInput = document.querySelector("#prompt");

  if (upscaleBtn) upscaleBtn.disabled = false;
  if (editBtn) {
    editBtn.disabled = !promptInput?.value?.trim();
  }
}

export async function refreshHistory(selectLatest = false) {
  try {
    const data = await apiFetch("/api/history", { cache: "no-store" });
    const versions = Array.isArray(data.versions) ? data.versions : [];
    setHistoryVersions(versions);

    if (selectLatest && versions.length > 0) {
      const latest = versions[versions.length - 1];
      selectHistoryVersion(latest);
    } else {
      renderHistory();
      updateSuggestCodexButton();
    }
  } catch (err) {
    console.error("Ошибка обновления истории:", err);
  }
}

export async function deleteVersion(version) {
  if (!confirm("Удалить версию и все её ответвления?")) return;

  try {
    const data = await apiFetch(`/api/history/${version.id}`, {
      method: "DELETE",
      cache: "no-store",
    });

    const versions = Array.isArray(data.versions) ? data.versions : [];
    setHistoryVersions(versions);

    const state = getState();
    state.collapsedGroups.delete(version.id);

    const currentSurvives = versions.some((v) => v.id === state.currentVersionId);
    if (!currentSurvives) {
      const parent = version.parentId ? versions.find((v) => v.id === version.parentId) : null;
      if (parent) {
        selectHistoryVersion(parent);
      } else if (versions.length > 0) {
        setCurrentVersionId(null);
        resetResult();
        updateDownloadCurrent(null);
        clearSourcePreview();
        renderHistory();
      } else {
        setCurrentVersionId(null);
        resetResult();
        updateDownloadCurrent(null);
        clearSourcePreview();
        renderHistory();
      }
    } else {
      renderHistory();
    }

    const refState = getReferenceState();
    if (refState?.source?.type === "history" && refState.source.versionId === version.id) {
      clearReference();
    }
  } catch (err) {
    setJobStatus("error", err.message || "Не удалось удалить версию.");
  }
}