package de.tstratmann.gpstracker

import android.content.Context
import android.location.Location
import java.io.File
import java.text.SimpleDateFormat
import java.util.*

class GPXManager(private val context: Context) {

    private var currentFile: File? = null

    fun startNewSession(): File {
        val timeStamp = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())
        val fileName = "track_$timeStamp.gpx"
        val file = File(context.filesDir, fileName)
        file.writeText(getGpxHeader())
        currentFile = file
        return file
    }

    fun appendLocation(location: Location) {
        currentFile?.let { file ->
            val time = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US).apply {
                timeZone = TimeZone.getTimeZone("UTC")
            }.format(Date(location.time))

            val trkpt = """
                <trkpt lat="${location.latitude}" lon="${location.longitude}">
                    <ele>${location.altitude}</ele>
                    <time>$time</time>
                </trkpt>
            """.trimIndent()

            val content = file.readText().removeSuffix(getGpxFooter())
            file.writeText(content + trkpt + getGpxFooter())
        }
    }

    fun getActivitiesCount(): Int {
        return context.filesDir.listFiles { _, name -> name.endsWith(".gpx") }?.size ?: 0
    }

    fun getAllFiles(): List<File> {
        return context.filesDir.listFiles { _, name -> name.endsWith(".gpx") }?.toList() ?: emptyList()
    }

    private fun getGpxHeader() = """
        <?xml version="1.0" encoding="UTF-8"?>
        <gpx version="1.1" creator="WearGPSTracker" xmlns="http://www.topografix.com/GPX/1/1">
            <trk>
                <name>Track ${SimpleDateFormat("yyyy-MM-dd HH:mm", Locale.getDefault()).format(Date())}</name>
                <trkseg>
    """.trimIndent()

    private fun getGpxFooter() = """
                </trkseg>
            </trk>
        </gpx>
    """.trimIndent()
}