package dev.castarr.tv.server

import org.junit.Assert.assertEquals
import org.junit.Assert.assertFalse
import org.junit.Assert.assertTrue
import org.junit.Test

class AttemptBudgetTest {

    private var clock = 0L
    private fun budget(
        windowMs: Long = 60_000L,
        maxFailures: Int = 5,
        maxTracked: Int = 64,
    ) = AttemptBudget(windowMs, maxFailures, maxTracked) { clock }

    /**
     * The 0.11.0 bug: the remote reconnects on every network hiccup, and
     * counting those successful handshakes threw the phone out after five.
     */
    @Test
    fun `successful connections never cost budget`() {
        val budget = budget()
        repeat(50) {
            assertTrue(budget.allows("10.0.0.5"))
            budget.clear("10.0.0.5")
        }
        assertTrue(budget.allows("10.0.0.5"))
    }

    @Test
    fun `five failures in the window lock the address out`() {
        val budget = budget()
        repeat(5) {
            assertTrue(budget.allows("10.0.0.5"))
            budget.recordFailure("10.0.0.5")
        }
        assertFalse(budget.allows("10.0.0.5"))
    }

    @Test
    fun `a success after failures wipes the slate`() {
        val budget = budget()
        repeat(4) { budget.recordFailure("10.0.0.5") }
        budget.clear("10.0.0.5")
        repeat(4) {
            assertTrue(budget.allows("10.0.0.5"))
            budget.recordFailure("10.0.0.5")
        }
        assertTrue(budget.allows("10.0.0.5"))
    }

    @Test
    fun `failures expire once the window has passed`() {
        val budget = budget()
        repeat(5) { budget.recordFailure("10.0.0.5") }
        assertFalse(budget.allows("10.0.0.5"))
        clock += 60_001
        assertTrue(budget.allows("10.0.0.5"))
    }

    @Test
    fun `the window slides, it does not reset in blocks`() {
        val budget = budget()
        repeat(4) {
            budget.recordFailure("10.0.0.5")
            clock += 20_000
        }
        // Two of the four are older than a minute by now, so there is room.
        assertTrue(budget.allows("10.0.0.5"))
    }

    @Test
    fun `one address cannot spend another's budget`() {
        val budget = budget()
        repeat(5) { budget.recordFailure("10.0.0.9") }
        assertFalse(budget.allows("10.0.0.9"))
        assertTrue(budget.allows("10.0.0.5"))
    }

    /** An attacker cycling source addresses must not grow the map forever. */
    @Test
    fun `tracked addresses stay bounded under a flood of fresh ones`() {
        val budget = budget(maxTracked = 8)
        repeat(500) { i ->
            budget.recordFailure("10.0.0.$i")
            clock += 10
        }
        assertTrue(budget.trackedAddresses() <= 8)
    }

    @Test
    fun `eviction drops the stale addresses, not the active one`() {
        val budget = budget(maxTracked = 4)
        repeat(4) { i -> budget.recordFailure("10.0.1.$i") }
        clock += 60_001
        repeat(5) { budget.recordFailure("10.0.0.5") }
        assertFalse(budget.allows("10.0.0.5"))
        assertEquals(1, budget.trackedAddresses())
    }
}