import React, { useMemo, useState } from 'react';
import {
  Card,
  CardContent,
  Typography,
  List,
  ListItem,
  ListItemText,
  Chip,
  Box,
  IconButton,
  Dialog,
  DialogTitle,
  DialogContent,
  DialogActions,
  Button,
  useTheme,
  useMediaQuery
} from '@mui/material';
import { Edit, Delete } from '@mui/icons-material';
import { FuelLogResponse } from '../types/fuel-logs.types';
import { fuelLogsApi } from '../api/fuel-logs.api';
import { useUnits } from '../../../core/units/UnitsContext';

interface FuelLogsListProps {
  logs?: FuelLogResponse[];
  onEdit?: (log: FuelLogResponse) => void;
  onDelete?: (logId: string) => void;
}

export const FuelLogsList: React.FC<FuelLogsListProps> = ({ logs, onEdit, onDelete }) => {
  const theme = useTheme();
  const isMobile = useMediaQuery(theme.breakpoints.down('sm'));
  const { unitSystem, convertDistance, convertVolume, currencySymbol } = useUnits();
  const [deleteDialogOpen, setDeleteDialogOpen] = useState(false);
  const [logToDelete, setLogToDelete] = useState<FuelLogResponse | null>(null);
  const [isDeleting, setIsDeleting] = useState(false);

  // Precompute previous odometer per log for delta calculations
  const prevOdoById = useMemo(() => {
    const map = new Map<string, number | undefined>();
    if (!Array.isArray(logs)) return map;
    const asc = [...logs].sort((a, b) => new Date(a.dateTime).getTime() - new Date(b.dateTime).getTime());
    let lastOdo: number | undefined = undefined;
    for (const l of asc) {
      map.set(l.id, lastOdo);
      if (typeof l.odometerReading === 'number' && !isNaN(l.odometerReading)) {
        lastOdo = l.odometerReading;
      }
    }
    return map;
  }, [logs]);

  const handleDeleteClick = (log: FuelLogResponse) => {
    setLogToDelete(log);
    setDeleteDialogOpen(true);
  };

  const handleDeleteConfirm = async () => {
    if (!logToDelete) return;

    try {
      setIsDeleting(true);
      await fuelLogsApi.delete(logToDelete.id);
      onDelete?.(logToDelete.id);
      setDeleteDialogOpen(false);
      setLogToDelete(null);
    } catch (error) {
      console.error('Failed to delete fuel log:', error);
      // TODO: Show error notification
    } finally {
      setIsDeleting(false);
    }
  };

  const handleDeleteCancel = () => {
    setDeleteDialogOpen(false);
    setLogToDelete(null);
  };
  // Defensive check for logs data
  if (!Array.isArray(logs) || logs.length === 0) {
    return (
      <Card variant="outlined">
        <CardContent>
          <Typography variant="body2" color="text.secondary">
            No fuel logs yet.
          </Typography>
        </CardContent>
      </Card>
    );
  }

  return (
    <>
      <List>
        {logs.map((log) => {
          // Defensive checks for each log entry
          if (!log || !log.id) {
            console.warn('[FuelLogsList] Invalid log entry:', log);
            return null;
          }

          try {
            // Safe date formatting
            const dateText = log.dateTime
              ? new Date(log.dateTime).toLocaleString()
              : 'Unknown date';

            // Safe cost formatting
            const totalCost = typeof log.totalCost === 'number'
              ? log.totalCost.toFixed(2)
              : '0.00';

            // Safe fuel units and cost per unit
            const fuelUnits = typeof log.fuelUnits === 'number'
              ? log.fuelUnits.toFixed(3)
              : '0.000';

            const costPerUnit = typeof log.costPerUnit === 'number'
              ? log.costPerUnit.toFixed(3)
              : '0.000';

            // Safe distance display
            const distanceText = log.odometerReading
              ? `Odo: ${log.odometerReading}`
              : log.tripDistance
                ? `Trip: ${log.tripDistance}`
                : 'No distance';

            // Compute local efficiency if not provided
            let localEffLabel: string | null = null;
            try {
              const gallons = typeof log.fuelUnits === 'number' ? log.fuelUnits : undefined;
              let miles: number | undefined =
                typeof log.tripDistance === 'number' && !isNaN(log.tripDistance)
                  ? log.tripDistance
                  : undefined;
              if (miles === undefined && typeof log.odometerReading === 'number') {
                const prev = prevOdoById.get(log.id);
                if (typeof prev === 'number' && log.odometerReading > prev) {
                  miles = log.odometerReading - prev;
                }
              }
              if (typeof miles === 'number' && typeof gallons === 'number' && gallons > 0) {
                if (unitSystem === 'metric') {
                  const km = convertDistance(miles);
                  const liters = convertVolume(gallons);
                  if (km > 0) localEffLabel = `${((liters / km) * 100).toFixed(1)} L/100km`;
                } else {
                  localEffLabel = `${(miles / gallons).toFixed(1)} MPG`;
                }
              }
            } catch {
              // Efficiency calculation failed, leave localEffLabel as null
            }

            return (
              <ListItem
                key={log.id}
                divider
                sx={{
                  flexDirection: isMobile ? 'column' : 'row',
                  alignItems: isMobile ? 'stretch' : 'center',
                  gap: isMobile ? 1 : 0,
                  py: isMobile ? 2 : 1,
                  '&:hover': {
                    backgroundColor: 'action.hover',
                  },
                  transition: 'background-color 0.2s ease-in-out',
                  cursor: 'default',
                }}
              >
                <Box sx={{
                  display: 'flex',
                  flexDirection: isMobile ? 'column' : 'row',
                  alignItems: isMobile ? 'flex-start' : 'center',
                  flex: 1,
                  gap: isMobile ? 0.5 : 1
                }}>
                  <ListItemText
                    primary={`${dateText} \u2013 ${currencySymbol}${totalCost}`}
                    secondary={`${fuelUnits} @ ${currencySymbol}${costPerUnit} \u2022 ${distanceText}`}
                    sx={{ flex: 1, minWidth: 0 }}
                  />
                  {(log.efficiency && typeof log.efficiency === 'number' && !isNaN(log.efficiency) && log.efficiencyLabel) || localEffLabel ? (
                    <Box sx={{ mr: isMobile ? 0 : 1 }}>
                      <Chip
                        label={
                          log.efficiency && log.efficiencyLabel
                            ? `${log.efficiency.toFixed(1)} ${log.efficiencyLabel}`
                            : localEffLabel || ''
                        }
                        size="small"
                        color="primary"
                      />
                    </Box>
                  ) : null}
                </Box>

                <Box sx={{
                  display: 'flex',
                  gap: isMobile ? 1 : 0.5,
                  justifyContent: isMobile ? 'center' : 'flex-end',
                  width: isMobile ? '100%' : 'auto'
                }}>
                  {onEdit && (
                    <IconButton
                      size={isMobile ? 'medium' : 'small'}
                      onClick={() => onEdit(log)}
                      sx={{
                        color: 'text.secondary',
                        minWidth: isMobile ? 48 : 'auto',
                        minHeight: isMobile ? 48 : 'auto',
                      }}
                    >
                      <Edit fontSize={isMobile ? 'medium' : 'small'} />
                    </IconButton>
                  )}
                  {onDelete && (
                    <IconButton
                      size={isMobile ? 'medium' : 'small'}
                      onClick={() => handleDeleteClick(log)}
                      sx={{
                        color: 'error.main',
                        minWidth: isMobile ? 48 : 'auto',
                        minHeight: isMobile ? 48 : 'auto',
                      }}
                    >
                      <Delete fontSize={isMobile ? 'medium' : 'small'} />
                    </IconButton>
                  )}
                </Box>
              </ListItem>
            );
          } catch (error) {
            console.error('[FuelLogsList] Error rendering log:', log, error);
            return (
              <ListItem key={log.id || Math.random()} divider>
                <ListItemText
                  primary="Error displaying fuel log"
                  secondary="Data formatting issue"
                />
              </ListItem>
            );
          }
        }).filter(Boolean)}
      </List>

      {/* Delete Confirmation Dialog */}
      <Dialog open={deleteDialogOpen} onClose={handleDeleteCancel}>
        <DialogTitle>Delete Fuel Log</DialogTitle>
        <DialogContent>
          <Typography>
            Are you sure you want to delete this fuel log entry? This action cannot be undone.
          </Typography>
          {logToDelete && (
            <Typography variant="body2" color="text.secondary" sx={{ mt: 1 }}>
              {new Date(logToDelete.dateTime).toLocaleString()} - {currencySymbol}{logToDelete.totalCost.toFixed(2)}
            </Typography>
          )}
        </DialogContent>
        <DialogActions>
          <Button onClick={handleDeleteCancel} disabled={isDeleting}>
            Cancel
          </Button>
          <Button
            onClick={handleDeleteConfirm}
            color="error"
            variant="contained"
            disabled={isDeleting}
          >
            {isDeleting ? 'Deleting...' : 'Delete'}
          </Button>
        </DialogActions>
      </Dialog>
    </>
  );
};
