import { useCallback, useEffect, useMemo, useState } from 'react'
import {
  Button, Dialog, DotLoading, Empty, Input, Popup, Segmented, Toast,
} from 'antd-mobile'
import { Celebrate } from '../../components/RingProgress.jsx'
import { checklistApi } from '../../api/checkin.js'
import useRefreshOnVisible from '../../hooks/useRefreshOnVisible.js'

// 清单视图: 进行中 / 已归档 / 模板 三类并列 (F-LS-*)
//   - 进行中 / 已归档: 清单本体, 勾选即完成
//   - 模板: 独立 CRUD (新建 / 编辑 / 删除), 按名称字母顺序排序 (中文按拼音)
//   - 新建清单: 只填名称, 模板从右侧滑出面板中选择 (不再使用场景选择器)
const NAME_COLLATOR = new Intl.Collator('zh-Hans-CN', { numeric: true, sensitivity: 'base' })
const byName = (a, b) => NAME_COLLATOR.compare(String(a.name || a.title || ''), String(b.name || b.title || ''))

export default function ListView() {
  const [tab, setTab] = useState('active')          // active | archived | template
  const [lists, setLists] = useState(null)
  const [err, setErr] = useState('')
  const [openId, setOpenId] = useState(null)
  const [newItem, setNewItem] = useState({})
  const [bursts, setBursts] = useState({})
  const [templates, setTemplates] = useState(null)
  const [showForm, setShowForm] = useState(false)
  const [form, setForm] = useState({ title: '', templateId: '' })
  const [pickerOpen, setPickerOpen] = useState(false)   // 右侧模板选择面板
  const [tplEdit, setTplEdit] = useState(null)          // { id, name, items[] } | null
  const [tplSaving, setTplSaving] = useState(false)

  const archived = tab === 'archived'

  const load = useCallback((silent) => {
    if (!silent) setErr('')
    checklistApi.lists(archived)
      .then((d) => setLists(d.items || []))
      .catch((e) => { if (!silent) setErr(e.message) })
  }, [archived])

  const loadTemplates = useCallback(() => {
    checklistApi.templates()
      .then((d) => setTemplates((d.items || []).slice().sort(byName)))
      .catch(() => setTemplates([]))
  }, [])

  useEffect(() => { setLists(null); load(false) }, [load])
  useRefreshOnVisible(() => { load(true); if (tab === 'template') loadTemplates() })
  useEffect(() => { loadTemplates() }, [loadTemplates])

  const withProgress = useCallback((list) => {
    const items = list.items || []
    const done = items.filter((i) => i.done).length
    return {
      ...list,
      total: items.length,
      done,
      percent: items.length > 0 ? done / items.length : 0,
      completed: items.length > 0 && done === items.length,
    }
  }, [])

  const patchList = (id, updater) =>
    setLists((prev) => (prev || []).map((l) => (l.id === id ? updater(l) : l)))

  // 勾选: 乐观更新 + 服务端确认 (F-LS-03, F-SY-06)
  async function toggleItem(listId, item) {
    const snapshot = lists
    const next = !item.done
    patchList(listId, (l) => withProgress({
      ...l,
      items: l.items.map((i) => (i.id === item.id ? { ...i, done: next } : i)),
    }))
    try {
      await checklistApi.updateItem(item.id, { done: next })
      const l = (lists || []).find((x) => x.id === listId)
      const updated = withProgress({
        ...l,
        items: l.items.map((i) => (i.id === item.id ? { ...i, done: next } : i)),
      })
      if (updated.completed) setBursts((m) => ({ ...m, [listId]: (m[listId] || 0) + 1 }))
    } catch (e) {
      setLists(snapshot)
      Toast.show({ content: e.message || '更新失败' })
    }
  }

  async function addItem(listId, title) {
    const t = String(title || '').trim()
    if (!t) return
    try {
      const { item } = await checklistApi.addItem(listId, { title: t })
      patchList(listId, (l) => withProgress({ ...l, items: [...l.items, item] }))
      setNewItem((m) => ({ ...m, [listId]: '' }))
    } catch (e) {
      Toast.show({ content: e.message || '添加失败' })
    }
  }

  async function removeItem(listId, itemId) {
    const snapshot = lists
    patchList(listId, (l) => withProgress({ ...l, items: l.items.filter((i) => i.id !== itemId) }))
    try {
      await checklistApi.removeItem(itemId)
    } catch (e) {
      setLists(snapshot)
      Toast.show({ content: e.message || '删除失败' })
    }
  }

  async function checkAll(listId, done) {
    const snapshot = lists
    patchList(listId, (l) => withProgress({ ...l, items: l.items.map((i) => ({ ...i, done })) }))
    try {
      const { item } = await checklistApi.checkAll(listId, done)
      patchList(listId, () => withProgress(item))
      if (item.completed) setBursts((m) => ({ ...m, [listId]: (m[listId] || 0) + 1 }))
    } catch (e) {
      setLists(snapshot)
      Toast.show({ content: e.message || '操作失败' })
    }
  }

  // ---------- 清单 ----------

  function openCreateForm(templateId = '') {
    setForm({ title: '', templateId })
    setShowForm(true)
  }

  async function createList() {
    const title = String(form.title || '').trim()
    if (!title) return Toast.show({ content: '请填写清单名称' })
    const tpl = templateById(form.templateId)
    try {
      await checklistApi.create({
        title,
        // 场景不再由用户选择: 沿用模板自带的场景 (无模板则为空), 兼容历史数据展示
        scene: tpl?.scene || '',
        templateId: form.templateId || undefined,
      })
      setShowForm(false)
      setForm({ title: '', templateId: '' })
      setTab('active')
      load(true)
    } catch (e) {
      Toast.show({ content: e.message || '创建失败' })
    }
  }

  async function duplicate(list) {
    try {
      await checklistApi.duplicate(list.id)
      Toast.show({ content: '已复制为新清单' })
      load(true)
    } catch (e) {
      Toast.show({ content: e.message || '复制失败' })
    }
  }

  async function saveAsTemplate(list) {
    const items = (list.items || []).map((i) => ({ title: i.title, note: i.note }))
    if (!items.length) return Toast.show({ content: '空清单无法存为模板' })
    try {
      await checklistApi.createTemplate({ name: list.title, scene: list.scene || '', items })
      Toast.show({ content: '已保存为模板' })
      loadTemplates()
    } catch (e) {
      Toast.show({ content: e.message || '保存失败' })
    }
  }

  async function toggleArchive(list) {
    try {
      await checklistApi.update(list.id, { archived: !list.archived })
      Toast.show({ content: list.archived ? '已恢复到进行中' : '已归档' })
      load(true)
    } catch (e) {
      Toast.show({ content: e.message || '操作失败' })
    }
  }

  async function removeList(list) {
    const ok = await Dialog.confirm({ content: `删除「${list.title}」？`, confirmText: '删除', cancelText: '取消' })
    if (!ok) return
    try {
      await checklistApi.remove(list.id)
      load(true)
    } catch (e) {
      Toast.show({ content: e.message || '删除失败' })
    }
  }

  // ---------- 模板 CRUD ----------

  function templateById(id) {
    if (!id) return null
    return (templates || []).find((t) => String(t.id) === String(id)) || null
  }

  function newTemplate() {
    setTplEdit({ id: null, name: '', items: [{ title: '' }], builtin: false })
  }

  function editTemplate(tpl) {
    if (tpl.builtin) return Toast.show({ content: '系统预置模板不可编辑' })
    setTplEdit({
      id: tpl.id,
      name: tpl.name,
      builtin: false,
      items: (Array.isArray(tpl.items) ? tpl.items : []).map((i) => ({
        title: String(i?.title || ''),
        note: String(i?.note || ''),
      })),
    })
  }

  function setTplItem(idx, title) {
    setTplEdit((t) => ({ ...t, items: t.items.map((it, i) => (i === idx ? { ...it, title } : it)) }))
  }

  function addTplItem() {
    setTplEdit((t) => ({ ...t, items: [...t.items, { title: '' }] }))
  }

  function removeTplItem(idx) {
    setTplEdit((t) => ({ ...t, items: t.items.filter((_, i) => i !== idx) }))
  }

  async function saveTemplate() {
    if (!tplEdit) return
    const name = String(tplEdit.name || '').trim()
    const items = tplEdit.items
      .map((i) => ({ title: String(i.title || '').trim(), note: String(i.note || '') }))
      .filter((i) => i.title)
    if (!name) return Toast.show({ content: '请填写模板名称' })
    if (name.length > 20) return Toast.show({ content: '模板名称不能超过 20 个字' })
    if (!items.length) return Toast.show({ content: '模板至少需要一个检查项' })
    setTplSaving(true)
    try {
      if (tplEdit.id) await checklistApi.updateTemplate(tplEdit.id, { name, items })
      else await checklistApi.createTemplate({ name, items })
      Toast.show({ content: tplEdit.id ? '已保存' : '模板已创建' })
      setTplEdit(null)
      loadTemplates()
    } catch (e) {
      Toast.show({ content: e.message || '保存失败' })
    } finally {
      setTplSaving(false)
    }
  }

  async function removeTemplate(tpl) {
    if (tpl.builtin) return Toast.show({ content: '系统预置模板不可删除' })
    const ok = await Dialog.confirm({
      content: `删除模板「${tpl.name}」？已创建的清单不受影响。`,
      confirmText: '删除',
      cancelText: '取消',
    })
    if (!ok) return
    try {
      await checklistApi.removeTemplate(tpl.id)
      Toast.show({ content: '模板已删除' })
      loadTemplates()
    } catch (e) {
      Toast.show({ content: e.message || '删除失败' })
    }
  }

  const sorted = useMemo(() => lists || [], [lists])
  const templateCount = (t) => (Array.isArray(t.items) ? t.items.length : 0)
  const selectedTpl = templateById(form.templateId)

  return (
    <div className="list-view">
      <div className="list-view-head">
        <Segmented
          options={[
            { label: '进行中', value: 'active' },
            { label: '已归档', value: 'archived' },
            { label: '模板', value: 'template' },
          ]}
          value={tab}
          onChange={(v) => setTab(v)}
        />
        {tab === 'template'
          ? <Button size="mini" color="primary" onClick={newTemplate}>+ 新建模板</Button>
          : <Button size="mini" color="primary" onClick={() => openCreateForm()}>+ 新建</Button>}
      </div>

      {/* ---------- 模板分类 ---------- */}
      {tab === 'template' && (
        <>
          {templates === null && <div className="monitor-loading"><DotLoading /> 加载中...</div>}
          {templates !== null && templates.length === 0 && (
            <Empty description="还没有模板">
              <Button color="primary" size="small" onClick={newTemplate}>创建第一个模板</Button>
            </Empty>
          )}
          <div className="template-wrap">
            {(templates || []).map((tpl) => (
              <div key={tpl.id} className="template-card">
                <div className="template-head">
                  <span className="template-name">{tpl.name}</span>
                  {tpl.builtin && <span className="template-badge">预置</span>}
                  <span className="template-count">{templateCount(tpl)} 项</span>
                </div>
                <div className="template-items">
                  {(Array.isArray(tpl.items) ? tpl.items : []).slice(0, 4).map((it, i) => (
                    <span key={i} className="template-item-chip">{it.title}</span>
                  ))}
                  {templateCount(tpl) > 4 && (
                    <span className="template-item-chip more">+{templateCount(tpl) - 4}</span>
                  )}
                </div>
                <div className="template-actions">
                  <span className="habit-link" onClick={() => openCreateForm(String(tpl.id))}>由此新建</span>
                  {!tpl.builtin && <span className="habit-link" onClick={() => editTemplate(tpl)}>编辑</span>}
                  {!tpl.builtin && <span className="habit-link danger" onClick={() => removeTemplate(tpl)}>删除</span>}
                </div>
              </div>
            ))}
          </div>
        </>
      )}

      {/* ---------- 清单列表 ---------- */}
      {tab !== 'template' && (
        <>
          {err && <div className="error-banner">{err}<span className="retry-link" onClick={() => load(false)}>重试</span></div>}
          {lists === null && !err && <div className="monitor-loading"><DotLoading /> 加载中...</div>}
          {lists !== null && !err && sorted.length === 0 && (
            <Empty description={archived ? '暂无归档清单' : '还没有检查清单'}>
              {!archived && <Button color="primary" size="small" onClick={() => openCreateForm()}>新建清单</Button>}
            </Empty>
          )}

          <div className="checklist-wrap">
            {sorted.map((list) => {
              const open = openId === list.id
              return (
                <div key={list.id} className={'checklist-card' + (list.completed ? ' done' : '')}>
                  <div className="checklist-head" onClick={() => setOpenId(open ? null : list.id)}>
                    <div className="checklist-title-row">
                      <span className="checklist-title">{list.title}</span>
                      {list.scene && <span className="checklist-scene">{list.scene}</span>}
                    </div>
                    <div className="checklist-progress-row">
                      <div className="checklist-bar">
                        <div
                          className="checklist-bar-fill"
                          style={{ width: Math.round((list.percent || 0) * 100) + '%' }}
                        />
                      </div>
                      <span className="checklist-count">{list.done}/{list.total}</span>
                      <span className={'checklist-arrow' + (open ? ' open' : '')}>›</span>
                    </div>
                  </div>

                  {open && (
                    <div className="checklist-body">
                      {(list.items || []).map((item) => (
                        <div key={item.id} className={'checklist-item' + (item.done ? ' done' : '')}>
                          <span
                            className="check-box"
                            onClick={(e) => { e.stopPropagation(); toggleItem(list.id, item) }}
                          >
                            <svg viewBox="0 0 24 24" width="14" height="14" fill="none">
                              <path d="M4 12.5l5 5L20 6.5" stroke="#fff" strokeWidth="3" strokeLinecap="round" strokeLinejoin="round" />
                            </svg>
                          </span>
                          <span className="checklist-item-title" onClick={() => toggleItem(list.id, item)}>
                            {item.title}
                            {item.note && <em>{item.note}</em>}
                          </span>
                          <span className="checklist-item-del" onClick={() => removeItem(list.id, item.id)}>×</span>
                        </div>
                      ))}

                      <div className="checklist-add">
                        <Input
                          placeholder="添加检查项"
                          value={newItem[list.id] || ''}
                          onChange={(v) => setNewItem((m) => ({ ...m, [list.id]: v }))}
                          onEnterPress={() => addItem(list.id, newItem[list.id])}
                        />
                        <Button size="mini" color="primary" onClick={() => addItem(list.id, newItem[list.id])}>添加</Button>
                      </div>

                      <div className="checklist-actions">
                        <span className="habit-link" onClick={() => checkAll(list.id, true)}>全选</span>
                        <span className="habit-link" onClick={() => checkAll(list.id, false)}>全不选</span>
                        <span className="habit-link" onClick={() => duplicate(list)}>复制</span>
                        <span className="habit-link" onClick={() => saveAsTemplate(list)}>存为模板</span>
                        <span className="habit-link" onClick={() => toggleArchive(list)}>{list.archived ? '恢复' : '归档'}</span>
                        <span className="habit-link danger" onClick={() => removeList(list)}>删除</span>
                      </div>
                    </div>
                  )}
                  <Celebrate fire={bursts[list.id] || 0} color="#00b578" />
                </div>
              )
            })}
          </div>
        </>
      )}

      {/* ---------- 新建清单 (名称 + 模板, 无场景) ---------- */}
      <Popup
        visible={showForm}
        onMaskClick={() => setShowForm(false)}
        bodyStyle={{ borderTopLeftRadius: 12, borderTopRightRadius: 12, paddingBottom: 16 }}
      >
        <div className="form-popup">
          <div className="form-title">新建检查清单</div>
          <div className="form-field">
            <label>名称</label>
            <Input
              placeholder="例如：出差 · 杭州"
              value={form.title}
              maxLength={20}
              onChange={(v) => setForm((f) => ({ ...f, title: v }))}
            />
          </div>
          <div className="form-field">
            <label>模板</label>
            <div className="template-pick-row" onClick={() => setPickerOpen(true)}>
              <span className={selectedTpl ? 'template-pick-name' : 'template-pick-name placeholder'}>
                {selectedTpl ? selectedTpl.name : '不使用模板（空白清单）'}
              </span>
              <span className="template-pick-meta">
                {selectedTpl ? `${templateCount(selectedTpl)} 项` : ''}
                <span className="template-pick-arrow">›</span>
              </span>
            </div>
          </div>
          <div className="form-actions">
            <Button block color="primary" onClick={createList}>创建</Button>
            <Button block fill="outline" onClick={() => setShowForm(false)} style={{ marginTop: 8 }}>取消</Button>
          </div>
        </div>
      </Popup>

      {/* ---------- 模板选择: 右侧滑出面板 ---------- */}
      <Popup
        visible={pickerOpen}
        position="right"
        onMaskClick={() => setPickerOpen(false)}
        bodyStyle={{ width: '78vw', maxWidth: 340, height: '100%', display: 'flex', flexDirection: 'column' }}
      >
        <div className="tpl-picker">
          <div className="tpl-picker-head">
            <span className="tpl-picker-title">选择模板</span>
            <span className="tpl-picker-close" onClick={() => setPickerOpen(false)}>×</span>
          </div>
          <div className="tpl-picker-tip">按名称字母顺序排列</div>
          <div className="tpl-picker-list">
            <div
              className={'tpl-picker-item' + (!form.templateId ? ' active' : '')}
              onClick={() => { setForm((f) => ({ ...f, templateId: '' })); setPickerOpen(false) }}
            >
              <span className="tpl-picker-name">不使用模板</span>
              <span className="tpl-picker-sub">空白清单</span>
            </div>
            {(templates || []).map((tpl) => (
              <div
                key={tpl.id}
                className={'tpl-picker-item' + (String(tpl.id) === String(form.templateId) ? ' active' : '')}
                onClick={() => { setForm((f) => ({ ...f, templateId: String(tpl.id) })); setPickerOpen(false) }}
              >
                <span className="tpl-picker-name">
                  {tpl.name}
                  {tpl.builtin && <span className="template-badge">预置</span>}
                </span>
                <span className="tpl-picker-sub">{templateCount(tpl)} 项</span>
              </div>
            ))}
            {templates !== null && templates.length === 0 && (
              <div className="tpl-picker-empty">还没有可用模板</div>
            )}
          </div>
        </div>
      </Popup>

      {/* ---------- 模板编辑 ---------- */}
      <Popup
        visible={!!tplEdit}
        onMaskClick={() => setTplEdit(null)}
        bodyStyle={{ borderTopLeftRadius: 12, borderTopRightRadius: 12, paddingBottom: 16, maxHeight: '82vh', overflowY: 'auto' }}
      >
        {tplEdit && (
          <div className="form-popup">
            <div className="form-title">{tplEdit.id ? '编辑模板' : '新建模板'}</div>
            <div className="form-field">
              <label>模板名称</label>
              <Input
                placeholder="例如：出差 / 露营"
                value={tplEdit.name}
                maxLength={20}
                onChange={(v) => setTplEdit((t) => ({ ...t, name: v }))}
              />
            </div>
            <div className="form-field">
              <label>检查项（{tplEdit.items.length}）</label>
              <div className="tpl-edit-items">
                {tplEdit.items.map((it, idx) => (
                  <div key={idx} className="tpl-edit-item">
                    <span className="tpl-edit-index">{idx + 1}</span>
                    <Input
                      placeholder="检查项内容"
                      value={it.title}
                      maxLength={40}
                      onChange={(v) => setTplItem(idx, v)}
                    />
                    <span className="checklist-item-del" onClick={() => removeTplItem(idx)}>×</span>
                  </div>
                ))}
                <Button size="mini" fill="outline" onClick={addTplItem} style={{ marginTop: 8 }}>+ 添加检查项</Button>
              </div>
            </div>
            <div className="form-actions">
              <Button block color="primary" loading={tplSaving} onClick={saveTemplate}>保存</Button>
              <Button block fill="outline" onClick={() => setTplEdit(null)} style={{ marginTop: 8 }}>取消</Button>
            </div>
          </div>
        )}
      </Popup>
    </div>
  )
}