package tinyvm

import java.security.MessageDigest
import java.time.Instant

abstract class Object(
    val type: String,
) {
    abstract val data: String

    fun hash(): String =
        MessageDigest
            .getInstance("SHA-1")
            .digest("$type ${data.length}\u0000$data".toByteArray())
            .toHex()
}

class Commit(
    val tree: Tree,
    val author: Author,
    val message: String,
    val timestamp: Instant,
) : Object("commit") {
    // Use \n\n for end of header in-case additional metadata is implemented in the future.
    override val data: String
        get() = "tree ${tree.hash()}\nauthor $author\ntimestamp ${timestamp.epochSecond}\n\n$message"
}

data class Author(
    val name: String,
    val email: String,
) {
    override fun toString(): String = "$name <$email>"
}