/* sheetjs (C) SheetJS -- https://sheetjs.com */

import React, { useState, useCallback } from 'react';
import { StyleSheet, Text, Button, Alert, Image, ScrollView } from 'react-native';
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';
import { read, utils, WorkSheet } from 'xlsx';

const make_width = (ws: WorkSheet): number[] => {
  const aoa = utils.sheet_to_json(ws, {header:1}), res: number[] = [];
  aoa.forEach((r) => { r.forEach((c, C) => { res[C] = Math.max(res[C]||60, String(c).length * 10); }); });
  for(let C = 0; C < res.length; ++C) if(!res[C]) res[C] = 60;
  return res;
};

function App(): JSX.Element {
  const [data, setData] = useState<any[]>([
    "SheetJS".split(""),
    [5,4,3,3,7,9,5],
    [8,6,7,5,3,0,9]
  ]);
  const [widths, setWidths] = useState<number[]>(Array.from({length:7}, () => 20));

  const importFile = useCallback(async() => {
    try {
      const ab = await (await fetch("https://docs.sheetjs.com/pres.numbers")).arrayBuffer();
      const wb = read(ab);

      /* convert first worksheet to AOA */
      const wsname = wb.SheetNames[0];
      const ws = wb.Sheets[wsname];
      const data = utils.sheet_to_json(ws, {header:1});
      /* update state */
      setData(data);
      setWidths(make_width(ws));
    } catch(err) {
      Alert.alert("importFile Error", "Error " + ((err as any).message || err));
    }
  }, []);

  return (
    <ScrollView contentContainerStyle={styles.container}>
      <Text style={styles.welcome}> </Text>
      <Text style={styles.welcome}> <Image source={require("./logo.png")} style={styles.image}/> &nbsp; SheetJS × React Native</Text>
      <Button onPress={importFile} title="Import data from a spreadsheet" color="#841584" />
      <Text style={styles.bolded}>Current Data</Text>
      <ScrollView style={styles.table} horizontal={true} >
        <Table style={styles.table}>
          <TableWrapper>
            <Row data={data[0]} style={styles.thead} textStyle={styles.text} widthArr={widths}/>
          </TableWrapper>
          <ScrollView>
            <TableWrapper>
              <Rows data={data.slice(1)} style={styles.tr} textStyle={styles.text} widthArr={widths}/>
            </TableWrapper>
          </ScrollView>
        </Table>
      </ScrollView>
    </ScrollView>
  );
}

const styles = StyleSheet.create({
  container: { flex: 1, justifyContent: 'center', alignItems: 'center', backgroundColor: '#F5FCFF' },
  welcome: { fontSize: 20, textAlign: 'center', margin: 10 },
  bolded: { textAlign: 'center', color: '#333333', marginBottom: 5, fontWeight: "bold" },
  thead: { height: 40, backgroundColor: '#f1f8ff' },
  tr: { height: 30 },
  text: { marginLeft: 5, },
  table: { width: "100%" },
  image: { height: 16, width: 16 }
});

export default App;
