/*
 * Copyright 2018 Balena.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { Drive, Mountpoint } from '..';

interface Dict<T> {
	[K: string]: T;
}

function parseLsblkLine(line: string): Dict<string> {
	const data: Dict<string> = {};
	let offset = 0;
	let key = '';
	let value = '';

	const keyChar = /[^"=]/;
	const whitespace = /\s+/;
	const escape = '\\';
	let state = 'key';

	while (offset < line.length) {
		if (state === 'key') {
			while (keyChar.test(line[offset])) {
				key += line[offset];
				offset += 1;
			}
			if (line[offset] === '=') {
				state = 'value';
				offset += 1;
			}
		} else if (state === 'value') {
			if (line[offset] !== '"') {
				throw new Error(`Expected '"', saw "${line[offset]}"`);
			}
			offset += 1;
			while (line[offset] !== '"' && line[offset - 1] !== escape) {
				value += line[offset];
				offset += 1;
			}
			if (line[offset] !== '"') {
				throw new Error(`Expected '"', saw "${line[offset]}"`);
			}
			offset += 1;
			data[key.toLowerCase()] = value.trim();
			key = '';
			value = '';
			state = 'space';
		} else if (state === 'space') {
			while (whitespace.test(line[offset])) {
				offset += 1;
			}
			state = 'key';
		} else {
			throw new Error(`Undefined state "${state}"`);
		}
	}

	return data;
}

function parseLsblk(output: string): Array<Dict<string>> {
	return output
		.trim()
		.split(/\r?\n/g)
		.map(parseLsblkLine);
}

function consolidate(
	devices: Array<Dict<string>>,
): Array<Dict<string> & { mountpoints: Mountpoint[] }> {
	const primaries = devices.filter(device => {
		return (
			device.type === 'disk' &&
			!device.name.startsWith('ram') &&
			!device.name.startsWith('sr')
		);
	});

	return primaries.map(device => {
		return Object.assign({}, device, {
			mountpoints: devices
				.filter(child => {
					return (
						['disk', 'part'].includes(child.type) &&
						child.mountpoint &&
						child.name.startsWith(device.name)
					);
				})
				.map(
					(child): Mountpoint => {
						return {
							path: child.mountpoint,
							label: child.label,
						};
					},
				),
		});
	});
}

function getDescription(
	device: Dict<string> & { mountpoints: Mountpoint[] },
): string {
	const description = [
		device.label || '',
		device.vendor || '',
		device.model || '',
	];
	if (device.mountpoints.length) {
		let subLabels = device.mountpoints
			.filter(c => {
				return (c.label && c.label !== device.label) || c.path;
			})
			.map(c => {
				return c.label || c.path;
			});
		subLabels = Array.from(new Set(subLabels));
		if (subLabels.length) {
			description.push(`(${subLabels.join(', ')})`);
		}
	}
	return description
		.join(' ')
		.replace(/\s+/g, ' ')
		.trim();
}

export function parse(stdout: string): Drive[] {
	const devices = consolidate(parseLsblk(stdout));

	return devices.map(
		(device: Dict<string> & { mountpoints: Mountpoint[] }): Drive => {
			const isVirtual = device.subsystems
				? /^block$/i.test(device.subsystems)
				: null;
			const isSCSI = device.tran
				? /^(?:sata|scsi|ata|ide|pci)$/i.test(device.tran)
				: null;
			const isUSB = device.tran ? /^usb$/i.test(device.tran) : null;
			const isReadOnly = Number(device.ro) === 1;
			const isRemovable =
				Number(device.rm) === 1 ||
				Number(device.hotplug) === 1 ||
				Boolean(isVirtual);

			return {
				enumerator: 'lsblk:pairs',
				busType: (device.tran || 'UNKNOWN').toUpperCase(),
				busVersion: null,
				device: '/dev/' + device.name,
				devicePath: null,
				raw: '/dev/' + device.name,
				description: getDescription(device) || device.name,
				error: null,
				size: Number(device.size) || null,
				blockSize: Number(device['phy-sec']) || 512,
				logicalBlockSize: Number(device['log-sec']) || 512,
				mountpoints: device.mountpoints,
				isReadOnly,
				isSystem: !isRemovable && !isVirtual,
				isVirtual,
				isRemovable,
				isCard: null,
				isSCSI,
				isUSB,
				isUAS: null,
			};
		},
	);
}