package irc

/** A minimally-parsed raw IRC protocol line. */
data class ParsedLine(
    val prefix: String?,     // e.g. "nick!user@host" or a server name
    val command: String,     // e.g. "PRIVMSG", "JOIN", "376", etc.
    val params: List<String> // trailing param (after ':') is params.last() if present
)

fun parseIrcLine(line: String): ParsedLine? {
    if (line.isBlank()) return null
    var rest = line
    var prefix: String? = null

    if (rest.startsWith(":")) {
        val spaceIdx = rest.indexOf(' ')
        if (spaceIdx == -1) return null
        prefix = rest.substring(1, spaceIdx)
        rest = rest.substring(spaceIdx + 1)
    }

    val trailingSplit = rest.indexOf(" :")
    val paramsStr: String
    val trailing: String?
    if (trailingSplit != -1) {
        paramsStr = rest.substring(0, trailingSplit)
        trailing = rest.substring(trailingSplit + 2)
    } else {
        paramsStr = rest
        trailing = null
    }

    val parts = paramsStr.split(" ").filter { it.isNotEmpty() }
    if (parts.isEmpty()) return null
    val command = parts[0].uppercase()
    val params = parts.drop(1).toMutableList()
    if (trailing != null) params.add(trailing)

    return ParsedLine(prefix, command, params)
}

/** Extracts just the nick portion from an IRC prefix like "nick!user@host". */
fun nickFromPrefix(prefix: String?): String? {
    if (prefix == null) return null
    val bangIdx = prefix.indexOf('!')
    return if (bangIdx != -1) prefix.substring(0, bangIdx) else prefix
}