/* xlsx.js (C) 2013-present SheetJS -- http://sheetjs.com */
/* vim: set ts=2: */
import { Component } from '@angular/core';

import * as XLSX from 'xlsx';

import { saveAs } from 'file-saver';

type AOA = Array<Array<any>>;

function s2ab(s: string): ArrayBuffer {
	const buf: ArrayBuffer = new ArrayBuffer(s.length);
	const view: Uint8Array = new Uint8Array(buf);
	for (let i = 0; i !== s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
	return buf;
}

@Component({
	selector: 'sheetjs',
	template: `
	<input type="file" (change)="onFileChange($event)" multiple="false" />
	<table class="sjs-table">
		<tr *ngFor="let row of data">
			<td *ngFor="let val of row">
				{{val}}
			</td>
		</tr>
	</table>
	<button (click)="export()">Export!</button>
	`
})

export class SheetJSComponent {
	data: AOA = [ [1, 2], [3, 4] ];
	wopts: XLSX.WritingOptions = { bookType: 'xlsx', type: 'binary' };
	fileName: string = 'SheetJS.xlsx';

	onFileChange(evt: any) {
		/* wire up file reader */
		const target: DataTransfer = <DataTransfer>(evt.target);
		if (target.files.length !== 1) throw new Error('Cannot use multiple files');
		const reader: FileReader = new FileReader();
		reader.onload = (e: any) => {
			/* read workbook */
			const bstr: string = e.target.result;
			const wb: XLSX.WorkBook = XLSX.read(bstr, {type: 'binary'});

			/* grab first sheet */
			const wsname: string = wb.SheetNames[0];
			const ws: XLSX.WorkSheet = wb.Sheets[wsname];

			/* save data */
			this.data = <AOA>(XLSX.utils.sheet_to_json(ws, {header: 1}));
		};
		reader.readAsBinaryString(target.files[0]);
	}

	export(): void {
		/* generate worksheet */
		const ws: XLSX.WorkSheet = XLSX.utils.aoa_to_sheet(this.data);

		/* generate workbook and add the worksheet */
		const wb: XLSX.WorkBook = XLSX.utils.book_new();
		XLSX.utils.book_append_sheet(wb, ws, 'Sheet1');

		/* save to file */
		const wbout: string = XLSX.write(wb, this.wopts);
		saveAs(new Blob([s2ab(wbout)]), this.fileName);
	}
}
