"""日志页：实时轮询 /api/logs，按级别过滤，可展开 traceback。

共享 _shared.py 的 BASE_CSS / SHARED_JS。
页面专属：级别过滤按钮、自动刷新开关、清空、traceback 折叠。

显示策略：
- 默认 INFO（仅阶段转换/模型加载卸载/任务流转开始结束），可切 DEBUG 看进度详情。
- 最新日志在顶部；用户向上滚动浏览历史时不会被自动刷新拉走（仅当停在顶部时跟随）。
- 轮询带指数退避，连续失败时拉长间隔，避免服务不可达时打爆。
"""

from __future__ import annotations

from ._shared import render_page

POLL_INTERVAL_LOGS = 2000      # 正常轮询间隔（ms）
POLL_MAX_INTERVAL = 30000      # 退避上限（ms）
DEFAULT_TAIL = 200

_PAGE_JS = f"""
const POLL_MIN_INTERVAL = {POLL_INTERVAL_LOGS};
const POLL_MAX_INTERVAL = {POLL_MAX_INTERVAL};
const DEFAULT_TAIL = {DEFAULT_TAIL};
const API = "/api/logs";

let currentLevel = "info";        // 默认 INFO
let autoRefresh = true;
let timer = null;
let pollInterval = POLL_MIN_INTERVAL;  // 动态退避
let userScrolled = false;          // 用户是否主动向下浏览历史

const containerEl = document.getElementById("logs");
const emptyEl = document.getElementById("empty");
const statusEl = document.getElementById("status");

const LEVEL_CLASS = {{
  DEBUG: "st-running", INFO: "st-done", WARNING: "st-fail", ERROR: "st-fail",
  CRITICAL: "st-fail"
}};

// 监听滚动：用户向下（往历史方向）浏览时暂停自动跟随，回到顶部则恢复
containerEl.addEventListener("scroll", () => {{
  // scrollTop 越小越靠近顶部（最新）。接近顶部 = 用户在看最新
  userScrolled = containerEl.scrollTop > 4;
}});

document.querySelectorAll(".filter").forEach(btn => {{
  btn.addEventListener("click", () => {{
    document.querySelectorAll(".filter").forEach(b => b.classList.remove("active"));
    btn.classList.add("active");
    currentLevel = btn.dataset.level;
    containerEl.innerHTML = "";
    pollInterval = POLL_MIN_INTERVAL;
    fetchLogs();
  }});
}});

document.getElementById("autorefresh").addEventListener("change", e => {{
  autoRefresh = e.target.checked;
  if (autoRefresh) {{ pollInterval = POLL_MIN_INTERVAL; fetchLogs(); }}
  else if (timer) {{ clearTimeout(timer); timer = null; }}
}});

document.getElementById("clear-btn").addEventListener("click", async () => {{
  if (!confirm("确定清空所有日志缓冲？")) return;
  try {{
    await fetch(API, {{ method: "DELETE" }});
    containerEl.innerHTML = "";
    statusEl.textContent = "已清空";
  }} catch (e) {{ statusEl.textContent = "清空失败"; }}
}});

async function fetchLogs() {{
  try {{
    const r = await fetch(`${{API}}?level=${{currentLevel}}&tail=${{DEFAULT_TAIL}}`);
    if (!r.ok) {{ statusEl.textContent = "HTTP " + r.status; scheduleNext(true); return; }}
    const data = await r.json();
    renderLogs(data.logs);
    statusEl.textContent = `${{data.count}} 条 · 更新 ${{fmtTime24(new Date())}}`;
    pollInterval = POLL_MIN_INTERVAL;  // 成功，重置间隔
    scheduleNext(false);
  }} catch (e) {{
    statusEl.textContent = "获取失败";
    scheduleNext(true);  // 失败，退避
  }}
}}

function renderLogs(logs) {{
  if (!logs || logs.length === 0) {{
    if (containerEl.children.length === 0) emptyEl.style.display = "block";
    return;
  }}
  emptyEl.style.display = "none";

  // 服务端已按时间升序返回（旧→新）。倒序渲染：最新在最上面。
  // 用 key=ts|level|logger|msg 去重（含 logger 名，避免不同模块同消息被误判重复）
  const existing = new Set(Array.from(containerEl.children).map(el => el.dataset.key));
  const wasAtTop = containerEl.scrollTop <= 4;
  const frag = document.createDocumentFragment();

  // 服务端按时间升序返回（旧→新）。倒序遍历 + appendChild → frag 内最新在前：
  //   logs[N-1]（最新）先 append → frag 第一个；logs[0]（最旧）最后 → frag 最后
  for (let i = logs.length - 1; i >= 0; i--) {{
    const log = logs[i];
    const key = `${{log.ts}}|${{log.level}}|${{log.logger}}|${{log.msg}}`;
    if (existing.has(key)) continue;
    frag.appendChild(buildRow(log, key));
  }}

  if (frag.children.length > 0) {{
    // 整块插入到容器顶部：最新日志在最上面
    containerEl.insertBefore(frag, containerEl.firstChild);
  }}

  // 裁剪：超出上限删最旧（底部）
  while (containerEl.children.length > DEFAULT_TAIL) {{
    containerEl.removeChild(containerEl.lastChild);
  }}

  // 仅当用户停在顶部（看最新）时保持滚定在顶，否则不打扰浏览历史
  if (wasAtTop && !userScrolled) {{
    containerEl.scrollTop = 0;
  }}
}}

function buildRow(log, key) {{
  const row = document.createElement("div");
  row.className = "log-row " + (LEVEL_CLASS[log.level] || "st-running");
  row.dataset.key = key;
  const hasTrace = !!log.traceback;
  row.innerHTML = `
    <span class="log-ts">${{escapeHtml(log.ts)}}</span>
    <span class="status-tag ${{LEVEL_CLASS[log.level] || 'st-running'}}">${{escapeHtml(log.level)}}</span>
    <span class="log-logger">${{escapeHtml(log.logger)}}</span>
    <span class="log-msg">${{escapeHtml(log.msg)}}${{hasTrace ? ' <span class="trace-toggle">[traceback]</span>' : ''}}</span>`;
  if (hasTrace) {{
    const pre = document.createElement("pre");
    pre.className = "trace";
    pre.textContent = log.traceback;
    pre.style.display = "none";
    row.appendChild(pre);
    row.querySelector(".trace-toggle").addEventListener("click", e => {{
      e.stopPropagation();
      pre.style.display = pre.style.display === "none" ? "block" : "none";
    }});
  }}
  return row;
}}

function scheduleNext(failed) {{
  if (!autoRefresh) return;
  if (failed) {{
    // 指数退避：每次失败 ×1.6，上限 30s
    pollInterval = Math.min(pollInterval * 1.6, POLL_MAX_INTERVAL);
  }}
  timer = setTimeout(fetchLogs, pollInterval);
}}

fetchLogs();
"""

_PAGE_CSS = """
.logs { border: 1px solid var(--border); border-radius: 10px; max-height: 70vh;
        overflow-y: auto; background: var(--card-bg);
        font-family: "SF Mono", "Cascadia Code", Consolas, monospace; font-size: 0.82em; }
.log-row { display: grid; grid-template-columns: 140px 70px 150px 1fr; gap: 0.5em;
           padding: 0.25em 0.8em; border-bottom: 1px solid var(--border); align-items: start; }
.log-row:hover { background: var(--accent-light); }
.log-ts { color: var(--muted); white-space: nowrap; }
.log-logger { color: var(--muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.log-msg { word-break: break-all; white-space: pre-wrap; }
.trace-toggle { color: var(--error); cursor: pointer; font-weight: 600; font-size: 0.85em; }
.trace { grid-column: 1 / -1; margin: 0.3em 0 0.5em; padding: 0.6em; background: #1e1e1e;
         color: #f44336; border-radius: 4px; font-size: 0.9em; overflow-x: auto; white-space: pre-wrap; }
.filters { display: flex; gap: 0.4em; }
.filter { padding: 0.3em 1em; border: 1px solid var(--border); border-radius: 14px;
          background: transparent; cursor: pointer; font-size: 0.85em; color: var(--muted);
          transition: background 0.15s, color 0.15s; }
.filter.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.filter:hover:not(.active) { background: var(--accent-light); }
.toggle { display: flex; align-items: center; gap: 0.3em; cursor: pointer; color: var(--muted); }
"""

_BODY = """
<h1>日志</h1>
<p class="sub">默认显示 INFO（任务流转/模型加载卸载）。切 DEBUG 看进度详情，切 警告+/仅错误 过滤问题。自动刷新每 2 秒，失败自动退避。最新日志在顶部，向下浏览历史时不会被拉走。</p>

<div class="toolbar">
  <div class="filters">
    <button class="filter" data-level="debug">全部 (DEBUG)</button>
    <button class="filter active" data-level="info">简略 (INFO)</button>
    <button class="filter" data-level="warning">警告+</button>
    <button class="filter" data-level="error">仅错误</button>
  </div>
  <div style="display:flex;align-items:center;gap:0.8em;">
    <label class="toggle"><input id="autorefresh" type="checkbox" checked> 自动刷新</label>
    <button id="clear-btn" class="btn-sm">清空</button>
    <span id="status" class="info"></span>
  </div>
</div>

<div id="logs" class="logs"></div>
<div id="empty" class="empty">暂无日志。</div>
"""


def render() -> str:
    return render_page(
        title="日志 — audio2text",
        nav_active="logs",
        body=_BODY,
        page_js=_PAGE_JS,
        page_css=_PAGE_CSS,
    )