/* xlsx.js (C) 2013-present  SheetJS -- http://sheetjs.com */
import XLSX from 'xlsx';
import React, { Component } from 'react';
import { 
	AppRegistry, 
	StyleSheet, 
	Text, 
	View, 
	Button, 
	Alert, 
	Image, 
	ScrollView, 
	TouchableWithoutFeedback 
} from 'react-native';
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';

// react-native-fs
import { writeFile, readFile, DocumentDirectoryPath } from 'react-native-fs';
const DDP = DocumentDirectoryPath + "/";
const input = res => res;
const output = str => str;

// react-native-fetch-blob
/*
import RNFetchBlob from 'react-native-fetch-blob';
const { writeFile, readFile, dirs:{ DocumentDir } } = RNFetchBlob.fs;
const DDP = DocumentDir + "/";
const input = res => res.map(x => String.fromCharCode(x)).join("");
const output = str => str.split("").map(x => x.charCodeAt(0));
*/

const make_cols = refstr => Array.from({length: XLSX.utils.decode_range(refstr).e.c + 1}, (x,i) => XLSX.utils.encode_col(i));
const make_width = refstr => Array.from({length: XLSX.utils.decode_range(refstr).e.c + 1}, () => 60);

export default class SheetJS extends Component {
	constructor(props) {
		super(props);
		this.state = {
			data: [[1,2,3],[4,5,6]],
			widthArr: [60, 60, 60],
			cols: make_cols("A1:C2")
		};
		this.importFile = this.importFile.bind(this);
		this.exportFile = this.exportFile.bind(this);
	};
	importFile() {
		Alert.alert("Rename file to sheetjs.xlsx", "Copy to " + DDP, [
			{text: 'Cancel', onPress: () => {}, style: 'cancel' },
			{text: 'Import', onPress: () => {
				readFile(DDP + "sheetjs.xlsx", 'ascii').then((res) => {
					/* parse file */
					const wb = XLSX.read(input(res), {type:'binary'});

					/* convert first worksheet to AOA */
					const wsname = wb.SheetNames[0];
					const ws = wb.Sheets[wsname];
					const data = XLSX.utils.sheet_to_json(ws, {header:1});

					/* update state */
					this.setState({ data: data, cols: make_cols(ws['!ref']), widthArr: make_width(ws['!ref']) });
				}).catch((err) => { Alert.alert("importFile Error", "Error " + err.message); });
			}}
		]);
	}
	exportFile() {
		/* convert AOA back to worksheet */
		const ws = XLSX.utils.aoa_to_sheet(this.state.data);

		/* build new workbook */
		const wb = XLSX.utils.book_new();
		XLSX.utils.book_append_sheet(wb, ws, "SheetJS");

		/* write file */
		const wbout = XLSX.write(wb, {type:'binary', bookType:"xlsx"});
		const file = DDP + "sheetjsw.xlsx";
		writeFile(file, output(wbout), 'ascii').then((res) =>{
				Alert.alert("exportFile success", "Exported to " + file);
		}).catch((err) => { Alert.alert("exportFile Error", "Error " + err.message); });
	};

	render() { 
		return (
			<ScrollView contentContainerStyle={styles.container} vertical={true}>
				<Text style={styles.welcome}> </Text>
				<Text style={styles.welcome}>SheetJS React Native Demo</Text>
				<Text style={styles.instructions}>Import Data</Text>
				<Button onPress={this.importFile} title="Import data from a spreadsheet" color="#841584" />
				<Text style={styles.instructions}>Export Data</Text>
				<Button disabled={!this.state.data.length} onPress={this.exportFile} title="Export data to XLSX" color="#841584" />

				<Text style={styles.instructions}>Current Data</Text>

				<ScrollView style={styles.table} horizontal={true} >
					<Table style={styles.table}>
						<TableWrapper>
							<Row data={this.state.cols} style={styles.thead} textStyle={styles.text} widthArr={this.state.widthArr}/>
						</TableWrapper>
						<TouchableWithoutFeedback>
							<ScrollView vertical={true}>
								<TableWrapper>
									<Rows data={this.state.data} style={styles.tr} textStyle={styles.text} widthArr={this.state.widthArr}/>
								</TableWrapper>
							</ScrollView>
						</TouchableWithoutFeedback>
					</Table>
				</ScrollView>
			</ScrollView>
		); 
	};
};

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

AppRegistry.registerComponent('SheetJS', () => SheetJS);