package com.shr4pnel.ferretirc.util

import ch.qos.logback.classic.Level
import ch.qos.logback.classic.spi.ILoggingEvent
import ch.qos.logback.core.pattern.CompositeConverter
import ch.qos.logback.core.pattern.color.BoldWhiteCompositeConverter
import ch.qos.logback.core.pattern.color.ForegroundCompositeConverterBase
import ch.qos.logback.core.pattern.color.ANSIConstants as ANSI

private fun center(severity: String, width: Int = 7): String {
    val pad = width - severity.length
    if (pad <= 0) return severity
    val leading = pad / 2
    return buildString {
        repeat(leading) { append(" ") }
        append(severity)
        repeat(pad - leading) { append(" ") }
    }
}

/** 8 bit ANSI codes (logback uses 3/4 bit which isn't always equivalent) */
object Codes {
    const val SET_DEFAULT_COLOR = ANSI.ESC_START + ANSI.RESET + ANSI.DEFAULT_FG + ANSI.ESC_END
    const val FG_START = ANSI.ESC_START + "38;5;"
    const val FG_BOLD_START = ANSI.ESC_START + ANSI.BOLD + "38;5;"
    const val BG_START = ANSI.ESC_START + "48;5;"
    const val RED = "9"
    const val BLACK = "16"
    const val GREEN = "22"
    const val BLUE = "27"
    const val ORANGE = "202"
    const val DIMMED_WHITE = "250"
    const val WHITE = "255"
    const val UNSET = ""
}

/**
 * Interface of HighlightingCompositeConverterExt, used to colour the background and foreground of log messages
 * depending on their severity.
 *
 * Inheritor of ForegroundCompositeConverterBase, the implementation controlling colour-based transformations of
 * log events
 *
 * @see HighlightingCompositeConverterExt
 * @see CompositeConverter
 */
abstract class ForegroundBackgroundCompositeConverter<E : ILoggingEvent> : ForegroundCompositeConverterBase<E>() {
    override fun transform(event: E, `in`: String) = buildString {
        val fg = getForegroundColorCode(event)
        val bg = getBackgroundColourCode(event)
        val severity = center(`in`.trim())
        if (fg.isNotEmpty()) {
            append(Codes.FG_BOLD_START)
            append(fg)
            append(ANSI.ESC_END)
        }
        if (bg.isNotEmpty()) {
            append(Codes.BG_START)
            append(getBackgroundColourCode(event))
            append(ANSI.ESC_END)
        }
        append(severity)
        append(Codes.SET_DEFAULT_COLOR)
    }

    abstract fun getBackgroundColourCode(event: ILoggingEvent): String
}

/**
 * Converter class extension for control over backgrounds and foregrounds<
 *
 * Overrides methods of ForegroundBackgroundCompositeConverter to specify the bg/fg colours depending on severity
 *
 * Adapted from [shuwada/logback-custom-color](https://github.com/shuwada/logback-custom-color)
 */
class HighlightingCompositeConverterExt : ForegroundBackgroundCompositeConverter<ILoggingEvent>() {
    override fun getForegroundColorCode(event: ILoggingEvent) = when (event.level) {
        Level.TRACE -> Codes.WHITE
        Level.DEBUG -> Codes.WHITE
        Level.WARN -> Codes.WHITE
        Level.INFO -> Codes.WHITE
        Level.ERROR -> Codes.WHITE
        else -> Codes.UNSET
    }

    override fun getBackgroundColourCode(event: ILoggingEvent) = when (event.level) {
        Level.TRACE -> Codes.BLACK
        Level.DEBUG -> Codes.GREEN
        Level.WARN -> Codes.ORANGE
        Level.INFO -> Codes.BLUE
        Level.ERROR -> Codes.RED
        else -> Codes.UNSET
    }
}

/**
 * Converter rule which pulls out the last string of the thread split by spaces
 */
class ThreadConverter<E> : CompositeConverter<E>() {
    override fun transform(event: E, `in`: String) = `in`.split(" ").last()
}

/**
 * Converter rule which converts text to bold white
 */
class BoldWhiteCompositeConverterExt<E> : BoldWhiteCompositeConverter<E>() {
    override fun transform(event: E, `in`: String) =
        Codes.FG_BOLD_START + Codes.DIMMED_WHITE + ANSI.ESC_END + `in` + Codes.SET_DEFAULT_COLOR
}