import React, { useState, useEffect } from 'react';
import {
  Card,
  Form,
  Input,
  Select,
  Button,
  Table,
  Modal,
  Descriptions,
  Divider,
  message,
  Space,
  Tag,
  Row,
  Col,
  InputNumber,
  Steps,
  Upload,
  Tooltip,
  Badge,
  Statistic,
  Progress,
  Alert,
} from 'antd';
import {
  ShoppingCartOutlined,
  UploadOutlined,
  CheckCircleOutlined,
  CloseCircleOutlined,
  SyncOutlined,
  DownloadOutlined,
  FileExcelOutlined,
  UserOutlined,
  DeleteOutlined,
  EyeOutlined,
} from '@ant-design/icons';
import type { ColumnsType } from 'antd/es/table';
import { b2bTradeDataSource, BatchOrder as BatchOrderType, BatchOrderItem, Customer } from '@/services/b2bTradeDataSource';

const { Option } = Select;
const { TextArea } = Input;

const BATCH_STATUS_MAP: Record<string, { color: string; text: string; icon: React.ReactNode }> = {
  DRAFT: { color: 'default', text: 'Draft', icon: <FileExcelOutlined /> },
  PENDING_REVIEW: { color: 'processing', text: 'Pending Review', icon: <SyncOutlined spin /> },
  CONFIRMED: { color: 'blue', text: 'Confirmed', icon: <CheckCircleOutlined /> },
  PROCESSING: { color: 'blue', text: 'Processing', icon: <SyncOutlined spin /> },
  COMPLETED: { color: 'success', text: 'Completed', icon: <CheckCircleOutlined /> },
  CANCELLED: { color: 'error', text: 'Cancelled', icon: <CloseCircleOutlined /> },
};

const ITEM_STATUS_MAP: Record<string, { color: string; text: string }> = {
  VALID: { color: 'success', text: 'Valid' },
  INVALID: { color: 'error', text: 'Invalid' },
  PENDING: { color: 'warning', text: 'Pending' },
};

export const B2BTradeBatchOrder: React.FC = () => {
  const [form] = Form.useForm();
  const [loading, setLoading] = useState(false);
  const [batchOrders, setBatchOrders] = useState<BatchOrderType[]>([]);
  const [customers, setCustomers] = useState<Customer[]>([]);
  const [orderItems, setOrderItems] = useState<BatchOrderItem[]>([]);
  const [currentStep, setCurrentStep] = useState(0);
  const [createModalVisible, setCreateModalVisible] = useState(false);
  const [detailModalVisible, setDetailModalVisible] = useState(false);
  const [selectedBatch, setSelectedBatch] = useState<BatchOrderType | null>(null);
  const [selectedCustomer, setSelectedCustomer] = useState<Customer | null>(null);
  const [fileList, setFileList] = useState<any[]>([]);
  const [stats, setStats] = useState({
    total: 0,
    pending: 0,
    processing: 0,
    completed: 0,
    totalAmount: 0,
  });

  useEffect(() => {
    fetchBatchOrders();
    fetchCustomers();
  }, []);

  const fetchBatchOrders = async () => {
    setLoading(true);
    try {
      const orders = await b2bTradeDataSource.fetchBatchOrders();
      setBatchOrders(orders);
      calculateStats(orders);
    } catch (error) {
      message.error('Failed to load batch orders');
    } finally {
      setLoading(false);
    }
  };

  const fetchCustomers = async () => {
    try {
      const data = await b2bTradeDataSource.fetchCustomers();
      setCustomers(data);
    } catch (error) {
      message.error('Failed to load customers');
    }
  };

  const calculateStats = (orders: BatchOrderType[]) => {
    setStats({
      total: orders.length,
      pending: orders.filter((o) => o.status === 'PENDING_REVIEW').length,
      processing: orders.filter((o) => o.status === 'PROCESSING').length,
      completed: orders.filter((o) => o.status === 'COMPLETED').length,
      totalAmount: orders.filter((o) => o.status === 'COMPLETED').reduce((sum, o) => sum + o.totalAmount, 0),
    });
  };

  const handleCustomerChange = (customerId: string) => {
    const customer = customers.find((c) => c.id === customerId);
    setSelectedCustomer(customer || null);
  };

  const handleFileUpload = (info: any) => {
    setFileList(info.fileList.slice(-1));
    if (info.file.status === 'done' || info.file) {
      parseUploadedFile(info.file);
    }
  };

  const parseUploadedFile = async (file: any) => {
    try {
      const items = await b2bTradeDataSource.parseUploadFile(file, selectedCustomer?.id || '');
      setOrderItems(items);
      setCurrentStep(1);
      message.success('File parsed successfully');
    } catch (error) {
      message.error('Failed to parse file');
    }
  };

  const handleRemoveItem = (key: string) => {
    setOrderItems(orderItems.filter((item) => item.key !== key));
  };

  const handleValidateItems = async () => {
    setLoading(true);
    try {
      const result = await b2bTradeDataSource.validateItems(orderItems);
      setOrderItems(result);
      const validCount = result.filter(i => i.status === 'VALID').length;
      const invalidCount = result.filter(i => i.status === 'INVALID').length;
      message.success(`Validation complete: ${validCount} valid, ${invalidCount} invalid`);
    } catch (error) {
      message.error('Validation failed');
    } finally {
      setLoading(false);
    }
  };

  const handleSubmitBatch = async () => {
    try {
      const values = await form.validateFields();
      const validItems = orderItems.filter((i) => i.status === 'VALID');
      if (validItems.length === 0) {
        message.error('No valid items to submit');
        return;
      }

      setLoading(true);
      await b2bTradeDataSource.createBatchOrder({
        customerId: values.customerId,
        items: validItems,
      });

      message.success('Batch order submitted successfully');
      setCurrentStep(2);
    } catch (error) {
      message.error('Failed to submit batch order');
    } finally {
      setLoading(false);
    }
  };

  const handleViewDetail = (batch: BatchOrderType) => {
    setSelectedBatch(batch);
    setDetailModalVisible(true);
  };

  const handleApproveBatch = async (batchId: string) => {
    setLoading(true);
    try {
      await b2bTradeDataSource.approveBatchOrder(batchId);
      message.success('Batch order approved');
      fetchBatchOrders();
    } catch (error) {
      message.error('Failed to approve batch order');
    } finally {
      setLoading(false);
    }
  };

  const handleDownloadTemplate = () => {
    message.info('Downloading template...');
  };

  const itemColumns: ColumnsType<BatchOrderItem> = [
    { title: 'Line', dataIndex: 'lineNumber', key: 'lineNumber', width: 60 },
    { title: 'SKU', dataIndex: 'sku', key: 'sku', width: 100 },
    { title: 'Product', dataIndex: 'productName', key: 'productName' },
    { title: 'Qty', dataIndex: 'quantity', key: 'quantity', width: 80 },
    {
      title: 'Unit Price',
      dataIndex: 'unitPrice',
      key: 'unitPrice',
      width: 100,
      render: (price: number) => `$${price.toFixed(2)}`,
    },
    {
      title: 'Total',
      dataIndex: 'totalPrice',
      key: 'totalPrice',
      width: 100,
      render: (price: number) => `$${price.toFixed(2)}`,
    },
    {
      title: 'Status',
      dataIndex: 'status',
      key: 'status',
      width: 90,
      render: (status: string) => {
        const config = ITEM_STATUS_MAP[status];
        return <Tag color={config.color}>{config.text}</Tag>;
      },
    },
    {
      title: 'Error',
      dataIndex: 'error',
      key: 'error',
      width: 150,
      render: (error?: string) => error ? <span style={{ color: '#f5222d' }}>{error}</span> : '-',
    },
    {
      title: 'Action',
      key: 'action',
      width: 80,
      render: (_, record) => (
        <Button type="link" danger icon={<DeleteOutlined />} onClick={() => handleRemoveItem(record.key)} />
      ),
    },
  ];

  const batchColumns: ColumnsType<BatchOrderType> = [
    {
      title: 'Batch ID',
      dataIndex: 'batchId',
      key: 'batchId',
      width: 130,
      render: (text: string, record) => (
        <a onClick={() => handleViewDetail(record)}>{text}</a>
      ),
    },
    {
      title: 'Customer',
      dataIndex: 'customerName',
      key: 'customerName',
      width: 180,
    },
    {
      title: 'Status',
      dataIndex: 'status',
      key: 'status',
      width: 130,
      render: (status: string) => {
        const config = BATCH_STATUS_MAP[status];
        return <Tag icon={config.icon} color={config.color}>{config.text}</Tag>;
      },
    },
    {
      title: 'Items',
      key: 'items',
      width: 120,
      render: (_, record) => (
        <Space>
          <Badge count={record.validItems} style={{ backgroundColor: '#52c41a' }} />
          <Badge count={record.invalidItems} style={{ backgroundColor: '#f5222d' }} />
        </Space>
      ),
    },
    {
      title: 'Amount',
      dataIndex: 'totalAmount',
      key: 'totalAmount',
      width: 120,
      render: (amount: number) => (
        <span style={{ fontWeight: 'bold' }}>${amount.toFixed(2)}</span>
      ),
    },
    {
      title: 'Created',
      dataIndex: 'createdAt',
      key: 'createdAt',
      width: 160,
    },
    {
      title: 'Actions',
      key: 'action',
      width: 150,
      fixed: 'right',
      render: (_, record) => (
        <Space>
          <Tooltip title="View Details">
            <Button type="link" icon={<EyeOutlined />} onClick={() => handleViewDetail(record)} />
          </Tooltip>
          {record.status === 'PENDING_REVIEW' && (
            <Tooltip title="Approve">
              <Button type="link" icon={<CheckCircleOutlined />} onClick={() => handleApproveBatch(record.batchId)} />
            </Tooltip>
          )}
        </Space>
      ),
    },
  ];

  const validCount = orderItems.filter((i) => i.status === 'VALID').length;
  const invalidCount = orderItems.filter((i) => i.status === 'INVALID').length;
  const totalAmount = orderItems.filter((i) => i.status === 'VALID').reduce((sum, item) => sum + item.totalPrice, 0);

  const steps = [
    { title: 'Upload', description: 'Select customer & upload file' },
    { title: 'Review', description: 'Validate items' },
    { title: 'Submit', description: 'Confirm & submit' },
  ];

  return (
    <div className="batch-order-page">
      <Row gutter={16} style={{ marginBottom: 24 }}>
        <Col span={4}>
          <Card>
            <Statistic title="Total Batches" value={stats.total} prefix={<ShoppingCartOutlined />} />
          </Card>
        </Col>
        <Col span={4}>
          <Card>
            <Statistic
              title="Pending Review"
              value={stats.pending}
              valueStyle={{ color: '#faad14' }}
            />
          </Card>
        </Col>
        <Col span={4}>
          <Card>
            <Statistic
              title="Processing"
              value={stats.processing}
              valueStyle={{ color: '#1890ff' }}
            />
          </Card>
        </Col>
        <Col span={4}>
          <Card>
            <Statistic
              title="Completed"
              value={stats.completed}
              valueStyle={{ color: '#52c41a' }}
            />
          </Card>
        </Col>
        <Col span={8}>
          <Card>
            <Statistic
              title="Total Amount"
              value={stats.totalAmount}
              precision={2}
              prefix="$"
              valueStyle={{ color: '#52c41a' }}
            />
          </Card>
        </Col>
      </Row>

      <Card
        title="Batch Orders"
        extra={
          <Button type="primary" icon={<ShoppingCartOutlined />} onClick={() => {
            setCreateModalVisible(true);
            setCurrentStep(0);
            setOrderItems([]);
            setFileList([]);
          }}>
            Create Batch Order
          </Button>
        }
      >
        <Table
          columns={batchColumns}
          dataSource={batchOrders}
          rowKey="id"
          loading={loading}
          scroll={{ x: 1100 }}
          pagination={{
            showSizeChanger: true,
            showTotal: (total) => `Total ${total} batches`,
          }}
        />
      </Card>

      <Modal
        title="Create Batch Order"
        open={createModalVisible}
        onCancel={() => setCreateModalVisible(false)}
        footer={null}
        width={1000}
      >
        <Steps current={currentStep} items={steps} style={{ marginBottom: 24 }} />

        {currentStep === 0 && (
          <Form form={form} layout="vertical">
            <Form.Item name="customerId" label="Customer" rules={[{ required: true }]}>
              <Select
                placeholder="Select customer"
                showSearch
                optionFilterProp="children"
                onChange={handleCustomerChange}
              >
                {customers.map((c) => (
                  <Option key={c.id} value={c.id}>
                    {c.name} ({c.company})
                  </Option>
                ))}
              </Select>
            </Form.Item>

            {selectedCustomer && (
              <Alert
                message={`Selected Customer: ${selectedCustomer.name} (${selectedCustomer.tier})`}
                type="info"
                showIcon
                style={{ marginBottom: 16 }}
              />
            )}

            <Divider>Upload Order File</Divider>

            <div style={{ marginBottom: 16 }}>
              <Button icon={<DownloadOutlined />} onClick={handleDownloadTemplate}>
                Download Template
              </Button>
            </div>

            <Upload
              accept=".xlsx,.xls,.csv"
              fileList={fileList}
              onChange={handleFileUpload}
              beforeUpload={() => false}
              maxCount={1}
            >
              <Button icon={<UploadOutlined />} disabled={!selectedCustomer}>
                Select File
              </Button>
            </Upload>

            <div style={{ marginTop: 16, color: '#666' }}>
              Supported formats: Excel (.xlsx, .xls), CSV (.csv)
            </div>
          </Form>
        )}

        {currentStep === 1 && (
          <>
            <Row gutter={16} style={{ marginBottom: 16 }}>
              <Col span={8}>
                <Card size="small">
                  <Statistic
                    title="Valid Items"
                    value={validCount}
                    valueStyle={{ color: '#52c41a' }}
                    prefix={<CheckCircleOutlined />}
                  />
                </Card>
              </Col>
              <Col span={8}>
                <Card size="small">
                  <Statistic
                    title="Invalid Items"
                    value={invalidCount}
                    valueStyle={{ color: '#f5222d' }}
                    prefix={<CloseCircleOutlined />}
                  />
                </Card>
              </Col>
              <Col span={8}>
                <Card size="small">
                  <Statistic
                    title="Total Amount"
                    value={totalAmount}
                    precision={2}
                    prefix="$"
                  />
                </Card>
              </Col>
            </Row>

            <div style={{ marginBottom: 16 }}>
              <Space>
                <Button onClick={handleValidateItems} loading={loading}>
                  Re-validate
                </Button>
                <Button onClick={() => setCurrentStep(0)}>Back</Button>
              </Space>
            </div>

            <Table
              columns={itemColumns}
              dataSource={orderItems}
              rowKey="key"
              pagination={false}
              scroll={{ y: 300 }}
              size="small"
            />

            <Form form={form} layout="vertical" style={{ marginTop: 16 }}>
              <Form.Item name="note" label="Note">
                <TextArea rows={2} placeholder="Add notes (optional)" />
              </Form.Item>
            </Form>

            <div style={{ textAlign: 'right', marginTop: 16 }}>
              <Space>
                <Button onClick={() => setCreateModalVisible(false)}>Cancel</Button>
                <Button
                  type="primary"
                  onClick={handleSubmitBatch}
                  loading={loading}
                  disabled={validCount === 0}
                >
                  Submit Batch Order
                </Button>
              </Space>
            </div>
          </>
        )}

        {currentStep === 2 && (
          <div style={{ textAlign: 'center', padding: '40px 0' }}>
            <CheckCircleOutlined style={{ fontSize: 64, color: '#52c41a' }} />
            <h2 style={{ marginTop: 24 }}>Batch Order Submitted</h2>
            <p style={{ color: '#666' }}>
              Your batch order has been submitted for review.
              <br />
              You will be notified once it is approved.
            </p>
            <Descriptions bordered column={1} style={{ maxWidth: 400, margin: '24px auto' }}>
              <Descriptions.Item label="Batch ID">BO-2026-NEW</Descriptions.Item>
              <Descriptions.Item label="Status">
                <Tag color="processing">Pending Review</Tag>
              </Descriptions.Item>
              <Descriptions.Item label="Valid Items">{validCount}</Descriptions.Item>
              <Descriptions.Item label="Total Amount">${totalAmount.toFixed(2)}</Descriptions.Item>
            </Descriptions>
            <Button type="primary" onClick={() => setCreateModalVisible(false)}>
              Done
            </Button>
          </div>
        )}
      </Modal>

      <Modal
        title="Batch Order Details"
        open={detailModalVisible}
        onCancel={() => setDetailModalVisible(false)}
        footer={[
          <Button key="close" onClick={() => setDetailModalVisible(false)}>
            Close
          </Button>,
        ]}
        width={700}
      >
        {selectedBatch && (
          <>
            <Descriptions bordered column={2}>
              <Descriptions.Item label="Batch ID">{selectedBatch.batchId}</Descriptions.Item>
              <Descriptions.Item label="Status">
                <Tag color={BATCH_STATUS_MAP[selectedBatch.status].color}>
                  {BATCH_STATUS_MAP[selectedBatch.status].text}
                </Tag>
              </Descriptions.Item>
              <Descriptions.Item label="Customer">{selectedBatch.customerName}</Descriptions.Item>
              <Descriptions.Item label="Currency">{selectedBatch.currency}</Descriptions.Item>
              <Descriptions.Item label="Valid Items">{selectedBatch.validItems}</Descriptions.Item>
              <Descriptions.Item label="Invalid Items">{selectedBatch.invalidItems}</Descriptions.Item>
              <Descriptions.Item label="Total Amount" span={2}>
                <span style={{ fontSize: 18, fontWeight: 'bold', color: '#1890ff' }}>
                  ${selectedBatch.totalAmount.toFixed(2)}
                </span>
              </Descriptions.Item>
              <Descriptions.Item label="Created">{selectedBatch.createdAt}</Descriptions.Item>
            </Descriptions>

            <Divider>Validation Progress</Divider>

            <Progress
              percent={Math.round((selectedBatch.validItems / selectedBatch.totalItems) * 100)}
              status={selectedBatch.invalidItems > 0 ? 'exception' : 'success'}
              format={() => `${selectedBatch.validItems}/${selectedBatch.totalItems} valid`}
            />
          </>
        )}
      </Modal>
    </div>
  );
};

export default B2BTradeBatchOrder;