//
//  CustomChartDateFormatter.swift
//  Charts
//
//  Created by wuxudong on 2018/10/6.
//

import Foundation
import DGCharts

open class CustomChartDateFormatter: NSObject, ValueFormatter, AxisValueFormatter {

    open var dateFormatter = DateFormatter();

    open var since = 0.0

    open var timeUnit : String?

    public override init() {

    }

    public init(pattern: String?, since: Double, timeUnit: String?, locale: String?) {
        self.dateFormatter.locale = Locale(identifier: locale ?? Locale.current.languageCode ?? "en_US");
        self.dateFormatter.dateFormat = pattern;
        self.since = since
        self.timeUnit = timeUnit
    }

    open func stringForValue(_ value: Double, axis: AxisBase?) -> String {
        return format(value)
    }

    open func stringForValue(_ value: Double, entry: ChartDataEntry, dataSetIndex: Int, viewPortHandler: ViewPortHandler?) -> String {
        return format(value)
    }

    fileprivate func format(_ value: Double) -> String
    {
        var span = 0.0

        // TODO: any better enum other than String equals to java.util.TimeUnit
        switch timeUnit {
        case "MILLISECONDS":
            span = value / 1000.0
        case "SECONDS":
            span = value
        case "MINUTES":
            span = value * 60
        case "HOURS":
            span = value * 60 * 60
        case "DAYS":
            span = value * 60 * 60 * 24
        default:
            span = value / 1000.0
        }

        let timeIntervalSince1970 = self.since / 1000.0 +  span

        let date = Date(timeIntervalSince1970: timeIntervalSince1970);
        return self.dateFormatter.string(from: date);
    }

}