import { useState } from 'react'
import {
  Alert,
  Button,
  Checkbox,
  Cascader,
  Code,
  ColorInput,
  Container,
  FileInput,
  Group,
  MultiSelect,
  NumberInput,
  Paper,
  PasswordInput,
  Radio,
  Select,
  SimpleGrid,
  Stack,
  Switch,
  TagsInput,
  Text,
  Textarea,
  TextInput,
  Title,
  useMatches,
} from '@mantine/core'
import { isEmail, useForm } from '@mantine/form'
import { UploadSimpleIcon } from '@phosphor-icons/react'
import classes from './page-form.module.css'

// 仅用于演示联动，不是完整行政区划数据。
const regions = [
  {
    name: '浙江省',
    cities: [
      { name: '杭州市', districts: ['西湖区', '拱墅区'] },
      { name: '宁波市', districts: ['海曙区', '鄞州区'] },
    ],
  },
  {
    name: '江苏省',
    cities: [
      { name: '南京市', districts: ['鼓楼区', '玄武区'] },
      { name: '苏州市', districts: ['姑苏区', '吴中区'] },
    ],
  },
]

const regionOptions = regions.map((province) => ({
  value: province.name,
  children: province.cities.map((city) => ({
    value: city.name,
    children: city.districts.map((district) => ({ value: district })),
  })),
}))

type FormValues = {
  name: string
  email: string
  role: string | null
  region: string[] | null
  contact: string
  interests: string[]
  technologies: string[]
  tags: string[]
  color: string
  files: File[]
  quantity: number | string
  password: string
  description: string
  notifications: boolean
  acceptedTerms: boolean
}

const exampleErrors = { email: '邮箱格式不正确，例如 name@example.com' }

export default function FormExample() {
  const [submitted, setSubmitted] = useState<string | null>(null)
  const withColumns = useMatches({ base: false, sm: true })
  const form = useForm<FormValues>({
    mode: 'controlled',
    validateInputOnBlur: true,
    initialErrors: exampleErrors,
    initialValues: {
      name: '',
      email: 'invalid-email',
      role: null,
      region: null,
      contact: 'email',
      interests: [],
      technologies: [],
      tags: [],
      color: '#228be6',
      files: [],
      quantity: 1,
      password: '',
      description: '',
      notifications: false,
      acceptedTerms: false,
    },
    validate: {
      name: (value) => value.trim() ? null : '请输入名称',
      email: (value) => !value.trim() ? '请输入邮箱' : isEmail(exampleErrors.email)(value.trim()),
      role: (value) => value ? null : '请选择角色',
      quantity: (value) => typeof value === 'number' && Number.isInteger(value) && value >= 0 && value <= 100
        ? null : '请输入 0–100 之间的整数',
      password: (value) => value && value.length < 8 ? '密码至少需要 8 位' : null,
      color: (value) => /^#[\da-f]{6}$/i.test(value) ? null : '请输入有效的六位 HEX 颜色',
      acceptedTerms: (value) => value ? null : '请先阅读并同意示例协议',
    },
  })

  function submit(values: FormValues) {
    setSubmitted(JSON.stringify({
      ...values,
      password: values.password ? '已填写（不展示密码）' : '未填写',
      files: values.files.map((file) => ({
        name: file.name,
        size: file.size,
        type: file.type || '未知类型',
      })),
    }, null, 2))
  }

  return (
    <Container size="xl" px={0}>
      <Stack gap="lg">
        <div>
          <Title order={1}>表单示例</Title>
          <Text c="dimmed">体验常用表单控件。提交后在本页预览结果，数据和文件不会发送到服务器。</Text>
        </div>

        <Paper withBorder p="md">
          <form
            onSubmit={form.onSubmit(submit, () => setSubmitted(null))}
            onReset={(event) => {
              event.preventDefault()
              form.reset()
              form.setErrors(exampleErrors)
              setSubmitted(null)
            }}
            noValidate
          >
            <Stack gap="lg">
              <Text size="sm" c="dimmed">带 * 的项目为必填项；离开输入框或提交时会校验。邮箱预填了错误值，用于演示错误提示。</Text>
              <SimpleGrid cols={{ base: 1, sm: 2 }} spacing="md">
                <TextInput
                  label="文本输入框"
                  placeholder="请输入名称"
                  required
                  {...form.getInputProps('name')}
                />
                <TextInput
                  label="邮箱（错误提示示例）"
                  description="修改为有效邮箱后可正常提交"
                  placeholder="name@example.com"
                  type="email"
                  autoComplete="email"
                  required
                  {...form.getInputProps('email')}
                />
                <Select
                  label="选择框"
                  placeholder="请选择角色"
                  data={['开发者', '设计师', '产品经理']}
                  searchable
                  clearable
                  required
                  {...form.getInputProps('role')}
                />
                <NumberInput
                  label="数值输入框"
                  description="数量，范围 0–100"
                  min={0}
                  max={100}
                  allowDecimal={false}
                  {...form.getInputProps('quantity')}
                />
                <PasswordInput
                  label="密码输入框"
                  description="选填，填写时至少 8 位"
                  placeholder="请输入示例密码"
                  autoComplete="new-password"
                  {...form.getInputProps('password')}
                />
              </SimpleGrid>

              <Cascader
                label="级联选择框"
                description="选择省、市、区，使用部分示例地区"
                placeholder="请选择省 / 市 / 区"
                data={regionOptions}
                withColumns={withColumns}
                searchable
                clearable
                closeOnSelect
                clearButtonProps={{ 'aria-label': '清空地区' }}
                nothingFoundMessage="没有匹配的地区"
                {...form.getInputProps('region')}
              />

              <SimpleGrid cols={{ base: 1, sm: 2 }} spacing="lg">
                <MultiSelect
                  label="下拉多选框"
                  description="选择多个技术方向"
                  placeholder="请选择技术方向"
                  data={['React', 'TypeScript', 'Vite', 'Mantine', 'Node.js']}
                  searchable
                  clearable
                  clearButtonProps={{ 'aria-label': '清空技术方向' }}
                  nothingFoundMessage="没有匹配的选项"
                  {...form.getInputProps('technologies')}
                />
                <TagsInput
                  label="标签输入框"
                  description="输入后按 Enter 或逗号添加标签，也可选择推荐标签"
                  placeholder="输入或选择标签"
                  data={['学习', '工作', '个人项目', '开源']}
                  clearable
                  clearButtonProps={{ 'aria-label': '清空标签' }}
                  {...form.getInputProps('tags')}
                />
                <Radio.Group label="单选框" description="偏好的联系方式" {...form.getInputProps('contact')}>
                  <Group mt="xs">
                    <Radio value="email" label="邮件" />
                    <Radio value="phone" label="电话" />
                    <Radio value="message" label="站内消息" />
                  </Group>
                </Radio.Group>
                <Checkbox.Group label="多选框" description="感兴趣的方向" {...form.getInputProps('interests')}>
                  <Group mt="xs">
                    <Checkbox value="frontend" label="前端" />
                    <Checkbox value="backend" label="后端" />
                    <Checkbox value="design" label="设计" />
                  </Group>
                </Checkbox.Group>
                <ColorInput
                  label="颜色选择框"
                  format="hex"
                  swatches={['#228be6', '#40c057', '#fab005', '#fa5252', '#7950f2']}
                  {...form.getInputProps('color')}
                />
                <FileInput
                  label="文件上传框"
                  description="支持选择多个文件，仅展示文件信息"
                  placeholder="点击选择文件"
                  leftSection={<UploadSimpleIcon aria-hidden="true" />}
                  multiple
                  clearable
                  {...form.getInputProps('files')}
                />
              </SimpleGrid>

              {form.values.files.length > 0 && (
                <Stack gap="xs" aria-live="polite">
                  {form.values.files.map((file, index) => (
                    <Text key={`${file.name}-${index}`} size="sm" className={classes.fileName}>
                      {file.name} · {(file.size / 1024).toFixed(1)} KB
                    </Text>
                  ))}
                </Stack>
              )}

              <Textarea
                label="文本框"
                description="多行文本，例如个人介绍或备注"
                placeholder="请输入内容"
                autosize
                minRows={3}
                maxRows={8}
                {...form.getInputProps('description')}
              />
              <Switch
                label="开关：接收消息通知"
                {...form.getInputProps('notifications', { type: 'checkbox' })}
              />
              <Stack gap="xs">
                <details>
                  <summary>查看示例协议</summary>
                  <Text size="sm" c="dimmed" py="xs">
                    本页面仅用于演示表单交互。提交内容仅在当前页面预览，文件不会上传。
                    勾选同意用于演示提交前的校验流程，不代表订购或开通服务。
                  </Text>
                </details>
                <Checkbox
                  label="我已阅读并同意示例协议"
                  required
                  {...form.getInputProps('acceptedTerms', { type: 'checkbox', withError: true })}
                />
              </Stack>
              <Group>
                <Button type="submit">提交预览</Button>
                <Button type="reset" variant="default">重置</Button>
              </Group>
            </Stack>
          </form>
        </Paper>

        {submitted !== null && (
          <Stack gap="xs">
            <Alert title="提交成功" color="green" role="status">以下是本次提交的示例数据。</Alert>
            <Code block>{submitted}</Code>
          </Stack>
        )}
      </Stack>
    </Container>
  )
}