import { showStatusMessage } from "./ui.js";
import { getActiveTVTab, openTVPanelTab, isTVPanelVisible, setTVPanelVisible } from "./tv.js";

// News aggregation now lives inside the shared media panel:
// - outer shell: #media-panel
// - this module renders into inner pane: #news-panel

const EARTH_NEWS_API = "/api/v1/news/earth-feed";
const FOCUS_UPDATE_INTERVAL_MS = 4000;
const DATA_REFRESH_INTERVAL_MS = 180000;
const MIN_REGION_SWITCH_INTERVAL_MS = 2500;
const REQUEST_TIMEOUT_MS = 15000;

let initialized = false;
let refreshPromise = null;
let payload = null;
let lastFocus = null;
let lastFetchAt = 0;
let lastRegionSwitchAt = 0;
function getElements() {
  return {
    toggleBtn: document.getElementById("toggle-news"),
    refreshBtn: document.getElementById("news-refresh"),
    openBtn: document.getElementById("news-open-external"),
    status: document.getElementById("news-board-status"),
    focusLabel: document.getElementById("news-focus-label"),
    focusCoords: document.getElementById("news-focus-coords"),
    sourceCount: document.getElementById("news-source-count"),
    regionChip: document.getElementById("news-region-chip"),
    board: document.getElementById("news-board-list"),
    empty: document.getElementById("news-board-empty"),
    feedAnchor: document.getElementById("news-feed-anchor"),
  };
}

function formatCoord(value, positiveLabel, negativeLabel) {
  const abs = Math.abs(value).toFixed(1);
  return `${abs}°${value >= 0 ? positiveLabel : negativeLabel}`;
}

function formatRelativeTime(raw) {
  if (!raw) return "刚刚同步";
  const date = new Date(raw);
  if (Number.isNaN(date.getTime())) return "刚刚同步";

  const diff = Date.now() - date.getTime();
  const minutes = Math.max(1, Math.round(diff / 60000));
  if (minutes < 60) return `${minutes} 分钟前`;
  const hours = Math.round(minutes / 60);
  if (hours < 24) return `${hours} 小时前`;
  const days = Math.round(hours / 24);
  return `${days} 天前`;
}

export function updateNewsToggleUI(visible) {
  const { toggleBtn } = getElements();
  if (!toggleBtn) return;
  const active = visible && getActiveTVTab() === "news";
  toggleBtn.classList.toggle("active", active);
  const tooltip = toggleBtn.querySelector(".earth-toolbar-tooltip");
  if (tooltip) {
    tooltip.textContent = active ? "关闭态势新闻" : "打开态势新闻";
  }
}

function renderEmptyState(message) {
  const { board, empty, status, openBtn } = getElements();
  if (board) board.innerHTML = "";
  if (empty) {
    empty.hidden = false;
    empty.textContent = message;
  }
  if (status) {
    status.textContent = "等待聚合新闻源";
  }
  if (openBtn) openBtn.disabled = true;
}

function renderPayload(nextPayload) {
  payload = nextPayload;
  const {
    board,
    empty,
    status,
    focusLabel,
    focusCoords,
    sourceCount,
    regionChip,
    openBtn,
    feedAnchor,
  } = getElements();

  if (!board || !status || !focusLabel || !focusCoords || !sourceCount || !regionChip) {
    return;
  }

  const items = Array.isArray(nextPayload?.items) ? nextPayload.items : [];
  const sources = Array.isArray(nextPayload?.sources) ? nextPayload.sources : [];
  const focus = nextPayload?.focus || {};

  focusLabel.textContent = focus.label || "全球焦点";
  regionChip.textContent = focus.region || "global";
  regionChip.style.setProperty("--news-accent", focus.accent || "#d6e6ff");

  if (typeof focus.lat === "number" && typeof focus.lon === "number") {
    focusCoords.textContent = `${formatCoord(focus.lat, "N", "S")} · ${formatCoord(focus.lon, "E", "W")}`;
  } else {
    focusCoords.textContent = "跟随当前视角自动聚焦";
  }

  sourceCount.textContent = `${sources.length} 路聚合源`;
  if (nextPayload?.stale) {
    status.textContent = `当前显示最近一次可用新闻缓存，共 ${items.length} 条`;
  } else {
    status.textContent = nextPayload?.errors?.length
      ? `已聚合 ${items.length} 条，部分源不可用`
      : `已聚合 ${items.length} 条态势新闻`;
  }

  if (feedAnchor) {
    const matchedSource = sources.find((source) => source.region === focus.region) || sources[0];
    feedAnchor.href = matchedSource?.homepage_url || "https://news.google.com/";
  }

  if (openBtn) {
    openBtn.disabled = !feedAnchor?.href;
  }

  if (items.length === 0) {
    board.innerHTML = "";
    if (empty) {
      empty.hidden = false;
      empty.textContent = "当前未拉到可用新闻，请稍后刷新或切换视角区域。";
    }
    return;
  }

  if (empty) empty.hidden = true;

  board.innerHTML = items
    .map((item) => {
      const cardClass = item.is_focus_match
        ? "news-story-card news-story-card--focus"
        : "news-story-card";
      const summary = item.summary
        ? `<div class="news-story-summary">${item.summary}</div>`
        : "";
      return `
        <a class="${cardClass}" href="${item.url}" target="_blank" rel="noreferrer noopener">
          <div class="news-story-meta">
            <span class="news-story-source">${item.source}</span>
            <span class="news-story-time">${formatRelativeTime(item.published_at)}</span>
          </div>
          <div class="news-story-title">${item.title}</div>
          ${summary}
          <div class="news-story-tags">
            <span class="news-story-tag">${item.region}</span>
            <span class="news-story-tag">${item.feed_name}</span>
          </div>
        </a>
      `;
    })
    .join("");
}

async function fetchNews(lat, lon) {
  const url = new URL(EARTH_NEWS_API, window.location.origin);
  if (typeof lat === "number") url.searchParams.set("lat", lat.toFixed(4));
  if (typeof lon === "number") url.searchParams.set("lon", lon.toFixed(4));

  const controller = new AbortController();
  const timeoutId = window.setTimeout(() => controller.abort(), REQUEST_TIMEOUT_MS);
  const response = await fetch(url.toString(), {
    cache: "no-store",
    signal: controller.signal,
  }).finally(() => {
    window.clearTimeout(timeoutId);
  });
  if (!response.ok) {
    throw new Error(`新闻源请求失败: ${response.status}`);
  }
  return response.json();
}

async function refreshNews(lat, lon, { silent = false } = {}) {
  if (refreshPromise) return refreshPromise;

  const { status } = getElements();
  if (status) {
    status.textContent = "正在同步全球态势新闻...";
  }

  refreshPromise = fetchNews(lat, lon)
    .then((nextPayload) => {
      renderPayload(nextPayload);
      lastFetchAt = Date.now();
      if (Array.isArray(nextPayload?.items) && nextPayload.items.length === 0) {
        const { status } = getElements();
        if (status) {
          status.textContent = "当前区域暂无可用新闻，已完成一次聚合尝试";
        }
      }
      return nextPayload;
    })
    .catch((error) => {
      console.error("加载 Earth RSS 新闻失败:", error);
      const message = error?.name === "AbortError"
        ? "新闻聚合请求超时，请稍后重试"
        : `新闻聚合暂时不可用: ${error?.message || "未知错误"}`;
      if (!payload) {
        renderEmptyState(message);
      } else if (!silent) {
        showStatusMessage("态势新闻同步失败", "error");
      }
      throw error;
    })
    .finally(() => {
      refreshPromise = null;
    });

  return refreshPromise;
}

function shouldRefreshForFocus(lat, lon, region) {
  const now = Date.now();
  if (!lastFocus) return true;
  if (region !== lastFocus.region && now - lastRegionSwitchAt > MIN_REGION_SWITCH_INTERVAL_MS) {
    lastRegionSwitchAt = now;
    return true;
  }
  if (now - lastFetchAt > DATA_REFRESH_INTERVAL_MS) return true;
  if (now - (lastFocus.updatedAt || 0) < FOCUS_UPDATE_INTERVAL_MS) return false;
  const latDrift = Math.abs((lat || 0) - (lastFocus.lat || 0));
  const lonDrift = Math.abs((lon || 0) - (lastFocus.lon || 0));
  return latDrift >= 18 || lonDrift >= 25;
}

function inferRegion(lat, lon) {
  if (typeof lat !== "number" || typeof lon !== "number") return "global";
  if (lon >= -170 && lon <= -30) return "americas";
  if (lon > -30 && lon <= 45) return lat >= 30 ? "europe" : "middle-east-africa";
  if (lon > 45 && lon <= 150) return lat < 10 ? "middle-east-africa" : "asia-pacific";
  return "asia-pacific";
}

function openCurrentSourceHomepage() {
  const { feedAnchor } = getElements();
  if (feedAnchor?.href) {
    window.open(feedAnchor.href, "_blank", "noopener,noreferrer");
  }
}

export function updateNewsViewFocus(coords) {
  if (!initialized) return;
  if (!coords || typeof coords.lat !== "number" || typeof coords.lon !== "number") return;

  const region = inferRegion(coords.lat, coords.lon);
  const nextFocus = {
    lat: coords.lat,
    lon: coords.lon,
    region,
    updatedAt: Date.now(),
  };

  const shouldRefresh = shouldRefreshForFocus(coords.lat, coords.lon, region);
  lastFocus = nextFocus;
  if (shouldRefresh) {
    refreshNews(coords.lat, coords.lon, { silent: true }).catch(() => {});
  }
}

export async function ensureNewsPanelReady() {
  if (!initialized) {
    initNewsPanel();
  }
  if (!payload) {
    await refreshNews(lastFocus?.lat, lastFocus?.lon);
  }
  return payload;
}

export function initNewsPanel() {
  if (initialized) return;
  initialized = true;

  const { toggleBtn, refreshBtn, openBtn } = getElements();

  updateNewsToggleUI(isTVPanelVisible());
  renderEmptyState("正在准备全球态势新闻聚合源...");

  const openNewsTab = async () => {
    openTVPanelTab("news");
    updateNewsToggleUI(true);
    try {
      await ensureNewsPanelReady();
    } catch {
      // surface already handled
    }
  };

  toggleBtn?.addEventListener("click", async () => {
    const visible = isTVPanelVisible();
    const active = visible && getActiveTVTab() === "news";

    if (!visible) {
      await openNewsTab();
      return;
    }

    if (!active) {
      await openNewsTab();
      return;
    }

    setTVPanelVisible(false);
    updateNewsToggleUI(false);
  });

  window.addEventListener("earth:tv-tab-change", () => {
    updateNewsToggleUI(isTVPanelVisible());
  });
  window.addEventListener("earth:tv-visibility-change", (event) => {
    updateNewsToggleUI(Boolean(event.detail?.visible));
  });

  refreshBtn?.addEventListener("click", async () => {
    try {
      await refreshNews(lastFocus?.lat, lastFocus?.lon);
      showStatusMessage("态势新闻已刷新", "info");
    } catch {
      showStatusMessage("态势新闻刷新失败", "error");
    }
  });

  openBtn?.addEventListener("click", openCurrentSourceHomepage);

  refreshNews(undefined, undefined, { silent: true }).catch(() => {});
}