package com.example.medilightv2android.services

import android.os.Environment
import java.io.File
import java.text.SimpleDateFormat
import java.util.*

/**
 * ADC 데이터를 일별 CSV 파일로 저장.
 *
 * 파일 위치: Downloads/VesiScan_ADC/YYYY-MM-DD.csv
 * 행: scan_id × 6채널 (측정 1회 = 6행)
 * 열: scan_id, timestamp, volume_ml, lr_ratio, channel, sample_0~sample_99
 */
object AdcCsvLogger {

    private val dayFmt = SimpleDateFormat("yyyy-MM-dd", Locale.US)
    private val timeFmt = SimpleDateFormat("HH:mm:ss.SSS", Locale.US)
    private var scanCounter = 0

    private fun getDir(): File {
        val dir = File(
            Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS),
            "VesiScan_ADC"
        )
        if (!dir.exists()) dir.mkdirs()
        return dir
    }

    private fun getTodayFile(): File {
        return File(getDir(), "${dayFmt.format(Date())}.csv")
    }

    /**
     * 6채널 ADC 데이터를 CSV에 append.
     *
     * @param channels 6채널 ADC 버퍼 (List<List<UShort>>)
     * @param volumeMl BV 추정 결과 (null이면 측정 실패)
     * @param lrRatio lr_ratio 값
     */
    fun log(
        channels: List<List<UShort>>,
        volumeMl: Double? = null,
        lrRatio: Double = 1.0
    ) {
        try {
            val file = getTodayFile()
            val isNew = !file.exists() || file.length() == 0L
            scanCounter++

            val timestamp = timeFmt.format(Date())
            val volStr = volumeMl?.let { "%.1f".format(it) } ?: ""
            val lrStr = "%.2f".format(lrRatio)

            java.io.FileWriter(file, !isNew).buffered().use { writer ->
                if (isNew) {
                    val header = buildString {
                        append("scan_id,timestamp,volume_ml,lr_ratio,channel")
                        for (i in 0 until 100) append(",s$i")
                    }
                    writer.write(header)
                    writer.newLine()
                }

                for ((chIdx, buffer) in channels.withIndex()) {
                    val row = buildString {
                        append("$scanCounter,$timestamp,$volStr,$lrStr,CH$chIdx")
                        for (sample in buffer) {
                            append(",${sample.toInt()}")
                        }
                        // 100개 미만이면 빈 칸으로 채움
                        for (i in buffer.size until 100) {
                            append(",")
                        }
                    }
                    writer.write(row)
                    writer.newLine()
                }
            }
        } catch (_: Exception) {
            // 로깅 실패는 앱 crash 방지
        }
    }
}