import {
  Box,
  Table,
  TableBody,
  TableCell,
  TableContainer,
  TableHead,
  TableRow,
  TextField,
  IconButton,
  MenuItem,
  Chip,
  Typography,
  Button,
  Tooltip,
} from '@mui/material';
import AddIcon from '@mui/icons-material/Add';
import DeleteIcon from '@mui/icons-material/Delete';
import ArrowUpwardIcon from '@mui/icons-material/ArrowUpward';
import ArrowDownwardIcon from '@mui/icons-material/ArrowDownward';
import type { PricingMode, LineItemSource } from '../../lib/api/lineItems';

export interface EditableLineItem {
  id: string | null;
  description: string;
  quantity: number;
  unit: string;
  unitPrice: number | null;
  totalPrice: number;
  pricingMode: PricingMode;
  sortOrder: number;
  source: LineItemSource;
}

interface LineItemEditorProps {
  items: EditableLineItem[];
  onChange: (items: EditableLineItem[]) => void;
  disabled?: boolean;
}

const SOURCE_COLORS: Record<LineItemSource, 'primary' | 'secondary' | 'default' | 'success'> = {
  AI: 'primary',
  Vendor: 'secondary',
  Manual: 'default',
  Historical: 'success',
};

const UNITS = ['each', 'sq ft', 'linear ft', 'hours', 'days', 'lot', 'gallon', 'ton'];

function createEmptyItem(sortOrder: number): EditableLineItem {
  return {
    id: null,
    description: '',
    quantity: 1,
    unit: 'each',
    unitPrice: 0,
    totalPrice: 0,
    pricingMode: 'UnitPrice',
    sortOrder,
    source: 'Manual',
  };
}

export default function LineItemEditor({ items, onChange, disabled = false }: LineItemEditorProps) {
  const updateItem = (index: number, field: keyof EditableLineItem, value: unknown) => {
    const updated = [...items];
    const current = updated[index];
    if (!current) return;
    updated[index] = { ...current, [field]: value };

    if (field === 'quantity' || field === 'unitPrice') {
      const item = updated[index]!;
      if (item.pricingMode === 'UnitPrice' || item.pricingMode === 'Both') {
        item.totalPrice = (item.quantity || 0) * (item.unitPrice || 0);
      }
    }

    onChange(updated);
  };

  const addItem = () => {
    const maxSort = items.length > 0 ? Math.max(...items.map((i) => i.sortOrder)) : 0;
    onChange([...items, createEmptyItem(maxSort + 1)]);
  };

  const removeItem = (index: number) => {
    const updated = items.filter((_, i) => i !== index);
    onChange(updated.map((item, i) => ({ ...item, sortOrder: i + 1 })));
  };

  const moveItem = (index: number, direction: -1 | 1) => {
    const targetIndex = index + direction;
    if (targetIndex < 0 || targetIndex >= items.length) return;
    const updated = [...items];
    const a = updated[index];
    const b = updated[targetIndex];
    if (!a || !b) return;
    updated[index] = b;
    updated[targetIndex] = a;
    onChange(updated.map((item, i) => ({ ...item, sortOrder: i + 1 })));
  };

  const subtotal = items.reduce((sum, item) => sum + item.totalPrice, 0);

  return (
    <Box>
      <Box sx={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', mb: 1 }}>
        <Typography variant="subtitle2">
          Line Items ({items.length})
        </Typography>
        {!disabled && (
          <Button size="small" startIcon={<AddIcon />} onClick={addItem}>
            Add Row
          </Button>
        )}
      </Box>

      <TableContainer sx={{ maxHeight: 480 }}>
        <Table size="small" stickyHeader>
          <TableHead>
            <TableRow>
              <TableCell sx={{ width: 60 }}>#</TableCell>
              <TableCell sx={{ minWidth: 200 }}>Description</TableCell>
              <TableCell sx={{ width: 80 }}>Qty</TableCell>
              <TableCell sx={{ width: 100 }}>Unit</TableCell>
              <TableCell sx={{ width: 110 }}>Unit Price</TableCell>
              <TableCell sx={{ width: 110 }}>Total</TableCell>
              <TableCell sx={{ width: 90 }}>Source</TableCell>
              {!disabled && <TableCell sx={{ width: 100 }}>Actions</TableCell>}
            </TableRow>
          </TableHead>
          <TableBody>
            {items.map((item, index) => (
              <TableRow key={item.id ?? `new-${index}`} hover>
                <TableCell>
                  {!disabled && (
                    <Box sx={{ display: 'flex', flexDirection: 'column', alignItems: 'center' }}>
                      <IconButton size="small" onClick={() => moveItem(index, -1)} disabled={index === 0} aria-label={`Move item ${index + 1} up`}>
                        <ArrowUpwardIcon sx={{ fontSize: 14 }} />
                      </IconButton>
                      <Typography variant="caption">{index + 1}</Typography>
                      <IconButton size="small" onClick={() => moveItem(index, 1)} disabled={index === items.length - 1} aria-label={`Move item ${index + 1} down`}>
                        <ArrowDownwardIcon sx={{ fontSize: 14 }} />
                      </IconButton>
                    </Box>
                  )}
                  {disabled && <Typography variant="caption">{index + 1}</Typography>}
                </TableCell>
                <TableCell>
                  <TextField
                    size="small"
                    fullWidth
                    multiline
                    maxRows={3}
                    value={item.description}
                    onChange={(e) => updateItem(index, 'description', e.target.value)}
                    disabled={disabled}
                    variant="standard"
                  />
                </TableCell>
                <TableCell>
                  <TextField
                    size="small"
                    type="number"
                    value={item.quantity}
                    onChange={(e) => updateItem(index, 'quantity', parseFloat(e.target.value) || 0)}
                    disabled={disabled}
                    variant="standard"
                    slotProps={{ htmlInput: { min: 0, step: 0.01 } }}
                  />
                </TableCell>
                <TableCell>
                  <TextField
                    size="small"
                    select
                    value={item.unit}
                    onChange={(e) => updateItem(index, 'unit', e.target.value)}
                    disabled={disabled}
                    variant="standard"
                    fullWidth
                  >
                    {UNITS.map((u) => (
                      <MenuItem key={u} value={u}>{u}</MenuItem>
                    ))}
                  </TextField>
                </TableCell>
                <TableCell>
                  <TextField
                    size="small"
                    type="number"
                    value={item.unitPrice ?? ''}
                    onChange={(e) => updateItem(index, 'unitPrice', parseFloat(e.target.value) || 0)}
                    disabled={disabled || item.pricingMode === 'TotalPrice'}
                    variant="standard"
                    slotProps={{ htmlInput: { min: 0, step: 0.01 } }}
                  />
                </TableCell>
                <TableCell>
                  <TextField
                    size="small"
                    type="number"
                    value={item.totalPrice}
                    onChange={(e) => updateItem(index, 'totalPrice', parseFloat(e.target.value) || 0)}
                    disabled={disabled || item.pricingMode === 'UnitPrice'}
                    variant="standard"
                    slotProps={{ htmlInput: { min: 0, step: 0.01 } }}
                    sx={{ fontWeight: 600 }}
                  />
                </TableCell>
                <TableCell>
                  <Chip
                    label={item.source}
                    size="small"
                    color={SOURCE_COLORS[item.source]}
                    variant="outlined"
                  />
                </TableCell>
                {!disabled && (
                  <TableCell>
                    <Tooltip title="Remove">
                      <IconButton size="small" color="error" onClick={() => removeItem(index)}>
                        <DeleteIcon fontSize="small" />
                      </IconButton>
                    </Tooltip>
                  </TableCell>
                )}
              </TableRow>
            ))}
            {items.length === 0 && (
              <TableRow>
                <TableCell colSpan={disabled ? 7 : 8} align="center" sx={{ py: 3 }}>
                  <Typography color="text.secondary">
                    No line items yet. {!disabled && 'Click "Add Row" to start.'}
                  </Typography>
                </TableCell>
              </TableRow>
            )}
          </TableBody>
        </Table>
      </TableContainer>

      <Box sx={{ display: 'flex', justifyContent: 'flex-end', mt: 1, pr: 2 }}>
        <Typography variant="subtitle1" sx={{ fontWeight: 700 }}>
          Total: {new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(subtotal)}
        </Typography>
      </Box>
    </Box>
  );
}