'use client';

import { useState, useEffect } from 'react';
import {
  Box,
  Typography,
  CircularProgress,
  Alert,
  ToggleButtonGroup,
  ToggleButton,
  FormControl,
  InputLabel,
  Select,
  MenuItem,
} from '@mui/material';
import {
  LineChart,
  Line,
  XAxis,
  YAxis,
  CartesianGrid,
  Tooltip,
  Legend,
  ResponsiveContainer,
  ReferenceLine,
} from 'recharts';
import { format } from 'date-fns';
import apiClient from '@/lib/api/client';

interface GrowthData {
  age: number; // months
  weight?: number; // kg
  height?: number; // cm
  headCircumference?: number; // cm
  date: string;
}

// WHO Growth Standards Percentiles (simplified for 0-24 months)
// These are approximate values - in production, use exact WHO data
const WHO_WEIGHT_PERCENTILES = {
  male: {
    p3: [3.3, 4.4, 5.1, 5.6, 6.0, 6.4, 6.7, 7.0, 7.2, 7.5, 7.7, 7.9, 8.1, 8.3, 8.5, 8.7, 8.9, 9.0, 9.2, 9.4, 9.5, 9.7, 9.9, 10.0, 10.2],
    p15: [3.6, 4.8, 5.5, 6.1, 6.5, 6.9, 7.2, 7.5, 7.8, 8.0, 8.3, 8.5, 8.7, 8.9, 9.1, 9.3, 9.5, 9.7, 9.9, 10.1, 10.3, 10.4, 10.6, 10.8, 11.0],
    p50: [4.0, 5.3, 6.1, 6.7, 7.2, 7.6, 8.0, 8.3, 8.6, 8.9, 9.2, 9.4, 9.7, 9.9, 10.1, 10.4, 10.6, 10.8, 11.0, 11.2, 11.5, 11.7, 11.9, 12.1, 12.3],
    p85: [4.4, 5.8, 6.7, 7.4, 7.9, 8.4, 8.8, 9.1, 9.5, 9.8, 10.1, 10.4, 10.6, 10.9, 11.2, 11.4, 11.7, 11.9, 12.2, 12.4, 12.7, 13.0, 13.2, 13.5, 13.7],
    p97: [4.8, 6.3, 7.3, 8.0, 8.6, 9.1, 9.5, 9.9, 10.3, 10.6, 11.0, 11.3, 11.6, 11.9, 12.2, 12.5, 12.8, 13.1, 13.4, 13.7, 14.0, 14.3, 14.6, 14.9, 15.2],
  },
  female: {
    p3: [3.2, 4.2, 4.8, 5.3, 5.7, 6.0, 6.3, 6.6, 6.8, 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.3, 8.5, 8.7, 8.8, 9.0, 9.2, 9.3, 9.5, 9.7],
    p15: [3.5, 4.6, 5.3, 5.8, 6.2, 6.5, 6.8, 7.1, 7.4, 7.6, 7.8, 8.1, 8.3, 8.5, 8.7, 8.9, 9.1, 9.3, 9.4, 9.6, 9.8, 10.0, 10.2, 10.4, 10.6],
    p50: [3.9, 5.1, 5.8, 6.4, 6.9, 7.3, 7.6, 7.9, 8.2, 8.5, 8.7, 9.0, 9.2, 9.5, 9.7, 10.0, 10.2, 10.4, 10.7, 10.9, 11.1, 11.4, 11.6, 11.8, 12.1],
    p85: [4.3, 5.6, 6.5, 7.1, 7.6, 8.0, 8.4, 8.7, 9.1, 9.4, 9.7, 10.0, 10.2, 10.5, 10.8, 11.0, 11.3, 11.6, 11.8, 12.1, 12.4, 12.6, 12.9, 13.2, 13.5],
    p97: [4.7, 6.1, 7.0, 7.7, 8.3, 8.7, 9.1, 9.5, 9.9, 10.2, 10.6, 10.9, 11.2, 11.5, 11.8, 12.1, 12.4, 12.7, 13.0, 13.3, 13.6, 13.9, 14.2, 14.5, 14.9],
  },
};

export default function GrowthCurve() {
  const [data, setData] = useState<GrowthData[]>([]);
  const [isLoading, setIsLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [metric, setMetric] = useState<'weight' | 'height' | 'headCircumference'>('weight');
  const [gender, setGender] = useState<'male' | 'female'>('male');

  useEffect(() => {
    fetchGrowthData();
  }, []);

  const fetchGrowthData = async () => {
    try {
      setIsLoading(true);
      // Fetch growth measurements from backend
      const response = await apiClient.get('/api/v1/activities/growth');
      const growthActivities = response.data.data;

      // Process growth data
      const processedData: GrowthData[] = growthActivities.map((activity: any) => {
        const ageInMonths = calculateAgeInMonths(activity.childBirthDate, activity.measurementDate);
        return {
          age: ageInMonths,
          weight: activity.weight,
          height: activity.height,
          headCircumference: activity.headCircumference,
          date: format(new Date(activity.measurementDate), 'MMM dd, yyyy'),
        };
      });

      // Sort by age
      processedData.sort((a, b) => a.age - b.age);

      setData(processedData);

      // Fetch child profile to determine gender
      const profileResponse = await apiClient.get('/api/v1/children/profile');
      if (profileResponse.data.data.gender) {
        setGender(profileResponse.data.data.gender.toLowerCase());
      }
    } catch (err: any) {
      console.error('Failed to fetch growth data:', err);
      // If endpoint doesn't exist, create sample data for demonstration
      if (err.response?.status === 404) {
        setData(createSampleData());
      } else {
        setError(err.response?.data?.message || 'Failed to load growth data');
      }
    } finally {
      setIsLoading(false);
    }
  };

  const calculateAgeInMonths = (birthDate: string, measurementDate: string): number => {
    const birth = new Date(birthDate);
    const measurement = new Date(measurementDate);
    const months = (measurement.getFullYear() - birth.getFullYear()) * 12 +
      (measurement.getMonth() - birth.getMonth());
    return Math.max(0, months);
  };

  const createSampleData = (): GrowthData[] => {
    // Sample data for demonstration (0-12 months)
    return [
      { age: 0, weight: 3.5, height: 50, headCircumference: 35, date: 'Birth' },
      { age: 1, weight: 4.5, height: 54, headCircumference: 37, date: '1 month' },
      { age: 2, weight: 5.5, height: 58, headCircumference: 39, date: '2 months' },
      { age: 3, weight: 6.3, height: 61, headCircumference: 40, date: '3 months' },
      { age: 4, weight: 7.0, height: 64, headCircumference: 41, date: '4 months' },
      { age: 6, weight: 7.8, height: 67, headCircumference: 43, date: '6 months' },
      { age: 9, weight: 8.9, height: 72, headCircumference: 45, date: '9 months' },
      { age: 12, weight: 9.8, height: 76, headCircumference: 46, date: '12 months' },
    ];
  };

  const getPercentileData = () => {
    const percentiles = WHO_WEIGHT_PERCENTILES[gender];
    const maxAge = Math.max(...data.map(d => d.age), 24);

    return Array.from({ length: maxAge + 1 }, (_, i) => ({
      age: i,
      p3: percentiles.p3[i] || null,
      p15: percentiles.p15[i] || null,
      p50: percentiles.p50[i] || null,
      p85: percentiles.p85[i] || null,
      p97: percentiles.p97[i] || null,
    }));
  };

  const handleMetricChange = (event: React.MouseEvent<HTMLElement>, newMetric: 'weight' | 'height' | 'headCircumference' | null) => {
    if (newMetric !== null) {
      setMetric(newMetric);
    }
  };

  const handleGenderChange = (event: any) => {
    setGender(event.target.value);
  };

  if (isLoading) {
    return (
      <Box sx={{ display: 'flex', justifyContent: 'center', py: 4 }}>
        <CircularProgress />
      </Box>
    );
  }

  if (error) {
    return (
      <Alert severity="error" sx={{ borderRadius: 2 }}>
        {error}
      </Alert>
    );
  }

  const percentileData = getPercentileData();
  const combinedData = percentileData.map(p => {
    const userDataPoint = data.find(d => Math.round(d.age) === p.age);
    return {
      ...p,
      userValue: userDataPoint?.[metric] || null,
    };
  });

  return (
    <Box>
      <Box sx={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', mb: 3 }}>
        <Box>
          <Typography variant="h6" gutterBottom fontWeight="600">
            Growth Curve (WHO Standards)
          </Typography>
          <Typography variant="body2" color="text.secondary">
            Track your child's growth against WHO percentiles
          </Typography>
        </Box>
        <Box sx={{ display: 'flex', gap: 2 }}>
          <FormControl size="small" sx={{ minWidth: 100 }}>
            <InputLabel>Gender</InputLabel>
            <Select value={gender} label="Gender" onChange={handleGenderChange}>
              <MenuItem value="male">Male</MenuItem>
              <MenuItem value="female">Female</MenuItem>
            </Select>
          </FormControl>
          <ToggleButtonGroup
            value={metric}
            exclusive
            onChange={handleMetricChange}
            size="small"
          >
            <ToggleButton value="weight">Weight</ToggleButton>
            <ToggleButton value="height">Height</ToggleButton>
            <ToggleButton value="headCircumference">Head</ToggleButton>
          </ToggleButtonGroup>
        </Box>
      </Box>

      {data.length === 0 ? (
        <Alert severity="info" sx={{ borderRadius: 2 }}>
          No growth measurements recorded yet. Start tracking to see growth curves!
        </Alert>
      ) : (
        <ResponsiveContainer width="100%" height={400}>
          <LineChart data={combinedData}>
            <CartesianGrid strokeDasharray="3 3" stroke="#f0f0f0" />
            <XAxis
              dataKey="age"
              stroke="#666"
              label={{ value: 'Age (months)', position: 'insideBottom', offset: -5 }}
            />
            <YAxis
              stroke="#666"
              label={{
                value: metric === 'weight' ? 'Weight (kg)' : metric === 'height' ? 'Height (cm)' : 'Head Circumference (cm)',
                angle: -90,
                position: 'insideLeft',
              }}
            />
            <Tooltip
              contentStyle={{
                backgroundColor: 'rgba(255, 255, 255, 0.95)',
                border: 'none',
                borderRadius: 8,
                boxShadow: '0 4px 6px rgba(0, 0, 0, 0.1)',
              }}
            />
            <Legend />

            {/* WHO Percentile Lines */}
            <Line
              type="monotone"
              dataKey="p3"
              stroke="#FFE4E1"
              strokeWidth={1}
              dot={false}
              name="3rd Percentile"
              strokeDasharray="5 5"
            />
            <Line
              type="monotone"
              dataKey="p15"
              stroke="#FFD4C9"
              strokeWidth={1}
              dot={false}
              name="15th Percentile"
              strokeDasharray="3 3"
            />
            <Line
              type="monotone"
              dataKey="p50"
              stroke="#FFB6C1"
              strokeWidth={2}
              dot={false}
              name="50th Percentile (Median)"
            />
            <Line
              type="monotone"
              dataKey="p85"
              stroke="#FFD4C9"
              strokeWidth={1}
              dot={false}
              name="85th Percentile"
              strokeDasharray="3 3"
            />
            <Line
              type="monotone"
              dataKey="p97"
              stroke="#FFE4E1"
              strokeWidth={1}
              dot={false}
              name="97th Percentile"
              strokeDasharray="5 5"
            />

            {/* User's Actual Data */}
            <Line
              type="monotone"
              dataKey="userValue"
              stroke="#FF1493"
              strokeWidth={3}
              dot={{ fill: '#FF1493', r: 6 }}
              name="Your Child"
            />
          </LineChart>
        </ResponsiveContainer>
      )}

      <Box sx={{ mt: 2 }}>
        <Typography variant="caption" color="text.secondary">
          * WHO (World Health Organization) growth standards are based on healthy breastfed children
          from diverse populations. Consult your pediatrician for personalized growth assessment.
        </Typography>
      </Box>
    </Box>
  );
}