import { useState, useCallback } from 'react';
import { useNavigate } from 'react-router-dom';
import { useMutation } from '@tanstack/react-query';
import {
  Box,
  Typography,
  Card,
  CardContent,
  TextField,
  Button,
  Grid,
  MenuItem,
  Autocomplete,
  CircularProgress,
} from '@mui/material';
import SendIcon from '@mui/icons-material/Send';
import { toast } from 'react-toastify';
import { proposalsApi, type CreateProposalRequest } from '../../../lib/api/proposals';
import { customersApi, type Customer } from '../../../lib/api/customers';
import { SERVICE_CATEGORIES, PRIORITIES } from '../../../constants';
import { queryClient } from '../../../lib/queryClient';

export default function ProposalFormPage() {
  const navigate = useNavigate();

  const [form, setForm] = useState<CreateProposalRequest>({
    workOrderNumber: '',
    customerName: '',
    customerAddress: '',
    scopeOfWork: '',
    serviceCategory: '',
    priority: 'Standard',
    notes: '',
  });

  const [customers, setCustomers] = useState<Customer[]>([]);
  const [customerLoading, setCustomerLoading] = useState(false);
  const [addresses, setAddresses] = useState<string[]>([]);
  const [vendorFile, setVendorFile] = useState<File | null>(null);

  const handleChange = (field: keyof CreateProposalRequest, value: string) => {
    setForm((prev) => ({ ...prev, [field]: value }));
  };

  const searchCustomers = useCallback(async (query: string) => {
    if (query.length < 2) return;
    setCustomerLoading(true);
    try {
      const results = await customersApi.search(query);
      setCustomers(results);
    } catch {
      setCustomers([]);
    } finally {
      setCustomerLoading(false);
    }
  }, []);

  const handleCustomerSelect = (_: unknown, value: Customer | string | null) => {
    if (!value) {
      setForm((prev) => ({ ...prev, customerName: '', customerAddress: '' }));
      setAddresses([]);
      return;
    }
    if (typeof value === 'string') {
      setForm((prev) => ({ ...prev, customerName: value, customerAddress: '' }));
      setAddresses([]);
    } else {
      setForm((prev) => ({ ...prev, customerName: value.name, customerAddress: value.addresses[0] || '' }));
      setAddresses(value.addresses);
    }
  };

  const createMutation = useMutation({
    mutationFn: async () => {
      const proposal = await proposalsApi.create(form);

      if (vendorFile) {
        const { uploadUrl } = await proposalsApi.uploadAttachment(proposal.id, vendorFile.name);
        await fetch(uploadUrl, {
          method: 'PUT',
          body: vendorFile,
          headers: { 'Content-Type': vendorFile.type || 'application/pdf' },
        });
      }

      return proposal;
    },
    onSuccess: (proposal) => {
      queryClient.invalidateQueries({ queryKey: ['proposals'] });
      toast.success(`Proposal ${proposal.proposalNumber} submitted`);
      navigate(`/proposals/${proposal.id}`);
    },
  });

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    createMutation.mutate();
  };

  const isValid =
    form.workOrderNumber.trim() &&
    form.customerName.trim() &&
    form.customerAddress.trim() &&
    form.scopeOfWork.trim() &&
    form.serviceCategory;

  return (
    <Box>
      <Typography variant="h5" sx={{ mb: 3 }}>
        New Proposal Request
      </Typography>

      <Card>
        <CardContent>
          <Box component="form" onSubmit={handleSubmit}>
            <Grid container spacing={3}>
              <Grid size={{ xs: 12, sm: 6 }}>
                <TextField
                  label="Work Order #"
                  required
                  fullWidth
                  value={form.workOrderNumber}
                  onChange={(e) => handleChange('workOrderNumber', e.target.value)}
                />
              </Grid>

              <Grid size={{ xs: 12, sm: 6 }}>
                <Autocomplete
                  freeSolo
                  options={customers}
                  getOptionLabel={(opt) => (typeof opt === 'string' ? opt : opt.name)}
                  loading={customerLoading}
                  onInputChange={(_, value) => searchCustomers(value)}
                  onChange={handleCustomerSelect}
                  renderInput={(params) => (
                    <TextField
                      {...params}
                      label="Customer"
                      required
                      slotProps={{
                        input: {
                          ...params.InputProps,
                          endAdornment: (
                            <>
                              {customerLoading && <CircularProgress size={20} />}
                              {params.InputProps.endAdornment}
                            </>
                          ),
                        },
                      }}
                    />
                  )}
                />
              </Grid>

              <Grid size={{ xs: 12 }}>
                {addresses.length > 1 ? (
                  <TextField
                    label="Customer Address"
                    required
                    fullWidth
                    select
                    value={form.customerAddress}
                    onChange={(e) => handleChange('customerAddress', e.target.value)}
                  >
                    {addresses.map((addr) => (
                      <MenuItem key={addr} value={addr}>
                        {addr}
                      </MenuItem>
                    ))}
                  </TextField>
                ) : (
                  <TextField
                    label="Customer Address"
                    required
                    fullWidth
                    value={form.customerAddress}
                    onChange={(e) => handleChange('customerAddress', e.target.value)}
                  />
                )}
              </Grid>

              <Grid size={{ xs: 12, sm: 6 }}>
                <TextField
                  label="Service Category"
                  required
                  fullWidth
                  select
                  value={form.serviceCategory}
                  onChange={(e) => handleChange('serviceCategory', e.target.value)}
                >
                  {SERVICE_CATEGORIES.map((cat) => (
                    <MenuItem key={cat} value={cat}>
                      {cat}
                    </MenuItem>
                  ))}
                </TextField>
              </Grid>

              <Grid size={{ xs: 12, sm: 6 }}>
                <TextField
                  label="Priority"
                  required
                  fullWidth
                  select
                  value={form.priority}
                  onChange={(e) => handleChange('priority', e.target.value)}
                >
                  {PRIORITIES.map((p) => (
                    <MenuItem key={p} value={p}>
                      {p}
                    </MenuItem>
                  ))}
                </TextField>
              </Grid>

              <Grid size={{ xs: 12 }}>
                <TextField
                  label="Scope of Work"
                  required
                  fullWidth
                  multiline
                  minRows={4}
                  value={form.scopeOfWork}
                  onChange={(e) => handleChange('scopeOfWork', e.target.value)}
                  placeholder="Describe the work needed..."
                />
              </Grid>

              <Grid size={{ xs: 12 }}>
                <TextField
                  label="Notes (optional)"
                  fullWidth
                  multiline
                  minRows={2}
                  value={form.notes}
                  onChange={(e) => handleChange('notes', e.target.value)}
                />
              </Grid>

              <Grid size={{ xs: 12 }}>
                <Button variant="outlined" component="label">
                  {vendorFile ? vendorFile.name : 'Attach Vendor Proposal (PDF)'}
                  <input
                    type="file"
                    hidden
                    accept=".pdf"
                    onChange={(e) => setVendorFile(e.target.files?.[0] || null)}
                  />
                </Button>
              </Grid>

              <Grid size={{ xs: 12 }}>
                <Box sx={{ display: 'flex', gap: 2, justifyContent: 'flex-end' }}>
                  <Button variant="text" onClick={() => navigate(-1)}>
                    Cancel
                  </Button>
                  <Button
                    type="submit"
                    variant="contained"
                    startIcon={<SendIcon />}
                    disabled={!isValid || createMutation.isPending}
                  >
                    {createMutation.isPending ? 'Submitting...' : 'Submit Proposal'}
                  </Button>
                </Box>
              </Grid>
            </Grid>
          </Box>
        </CardContent>
      </Card>
    </Box>
  );
}