package com.gacy.android.service

import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import java.text.SimpleDateFormat
import java.util.Date
import java.util.Locale

object LogBuffer {

    private const val MAX_LOG_LINES = 500
    private const val MAX_DIAGNOSTIC_LINES = 100
    private val timeFormat = SimpleDateFormat("HH:mm:ss", Locale.getDefault())
    private val diagnostics = ArrayDeque<String>()

    private val _logs = MutableStateFlow<List<String>>(emptyList())
    val logs: StateFlow<List<String>> = _logs.asStateFlow()

    @Synchronized
    fun append(message: String) {
        val timestamp = timeFormat.format(Date())
        val formatted = "[$timestamp] $message"
        if (isDiagnostic(message)) {
            diagnostics.addLast(formatted)
            if (diagnostics.size > MAX_DIAGNOSTIC_LINES) diagnostics.removeFirst()
        }
        val current = _logs.value.toMutableList()
        current.add(formatted)
        if (current.size > MAX_LOG_LINES) {
            current.removeAt(0)
        }
        _logs.value = current
    }

    @Synchronized
    fun clear() {
        _logs.value = emptyList()
        diagnostics.clear()
    }

    @Synchronized
    fun getAllText(): String {
        val recent = _logs.value
        val olderDiagnostics = diagnostics.filterNot { it in recent }
        return (olderDiagnostics + recent).joinToString("\n")
    }

    private fun isDiagnostic(message: String): Boolean =
        "[gateway]" in message || "[DISPATCH]" in message ||
            "[KCP] handshake rejected:" in message || "[KCP] packet rejected:" in message ||
            "New connection from addr:" in message || "[Server error]" in message
}