package com.peachpasswords.vault

/** Restores the durable slot set after a partially committed vault transaction. */
internal class VaultSlotRollback(private val store: VaultStorage) {
    fun restoreTriad(
        priorA: StoredVault?,
        priorB: String?,
        priorD: StoredVault?,
    ): List<String> {
        val failures = mutableListOf<String>()
        if (priorA == null) {
            runCatching { store.clearVault() }.onFailure { failures += "clearVault: $it" }
            return failures
        }

        attempt(failures, "writeSlotA") { store.writeSlotA(priorA) }
        if (priorB != null) attempt(failures, "writeSlotB") { store.writeSlotB(priorB) }
        if (priorD != null) {
            attempt(failures, "writeDecoySlot") { store.writeDecoySlot(priorD) }
        } else {
            runCatching { store.clearDecoySlot() }.onFailure { failures += "clearDecoySlot: $it" }
        }
        return failures
    }

    fun restorePair(priorA: StoredVault, priorB: String?): List<String> {
        val failures = mutableListOf<String>()
        attempt(failures, "writeSlotA") { store.writeSlotA(priorA) }
        if (priorB != null) attempt(failures, "writeSlotB") { store.writeSlotB(priorB) }
        return failures
    }

    private inline fun attempt(
        failures: MutableList<String>,
        operation: String,
        block: () -> Boolean,
    ) {
        runCatching { if (!block()) failures += "$operation returned false" }
            .onFailure { failures += "$operation: $it" }
    }
}