package com.example.aiapp

import java.time.OffsetDateTime
import kotlin.test.Test
import kotlin.test.assertEquals

class SessionUsageTest {
    @Test
    fun `usage snapshots stay with the session's machine and provider`() {
        val claude = snapshot("machine", "claude", null)
        val codex = snapshot("machine", "codex", "codex")
        val reserve = snapshot("machine", "codex", "gpt-reserve")
        val elsewhere = snapshot("other", "codex", "codex")

        assertEquals(
            listOf(codex, reserve),
            usageSnapshotsFor(
                listOf(claude, codex, reserve, elsewhere),
                machine = "machine",
                provider = "codex",
            ),
        )
    }

    @Test
    fun `a session without a meter has no usage snapshots`() {
        assertEquals(
            emptyList(),
            usageSnapshotsFor(
                listOf(snapshot("machine", "claude", null)),
                machine = "machine",
                provider = null,
            ),
        )
    }

    @Test
    fun `the model selects its named pool and other models use the generic pool`() {
        val generic = snapshot("machine", "codex", "codex")
        val spark =
            snapshot(
                "machine",
                "codex",
                "codex_bengalfox",
                limitName = "GPT-5.3-Codex-Spark",
            )
        val reserve =
            snapshot("machine", "codex", "base_model_inference", limitName = "gpt-reserve")
        val pools = listOf(generic, spark, reserve)

        assertEquals(spark, usagePoolFor(pools, "gpt-5.3-codex-spark"))
        assertEquals(reserve, usagePoolFor(pools, "gpt-5.6-luna"))
        assertEquals(generic, usagePoolFor(pools, "gpt-6-astra"))
    }

    @Test
    fun `the bar uses the shortest reported cycle`() {
        val weekly = window("Weekly", 10_080)
        val hourly = window("5-hour window", 300)

        assertEquals(hourly, shortestUsageWindow(listOf(weekly, hourly)))
        assertEquals(null, shortestUsageWindow(listOf(window("unknown", null))))
    }

    @Test
    fun `the time cursor follows elapsed time through the window`() {
        val now = OffsetDateTime.parse("2026-09-17T12:00:00Z")

        assertEquals(
            0.4f,
            usageWindowElapsedFraction(
                window("5-hour window", 300, "2026-09-17T15:00:00Z"),
                now,
            ),
        )
    }

    @Test
    fun `the time cursor clamps at the window ends`() {
        val now = OffsetDateTime.parse("2026-09-17T12:00:00Z")

        assertEquals(
            0f,
            usageWindowElapsedFraction(
                window("5-hour window", 300, "2026-09-17T18:00:00Z"),
                now,
            ),
        )
        assertEquals(
            1f,
            usageWindowElapsedFraction(
                window("5-hour window", 300, "2026-09-17T11:00:00Z"),
                now,
            ),
        )
    }

    @Test
    fun `the time cursor is absent without a usable duration and reset time`() {
        val now = OffsetDateTime.parse("2026-09-17T12:00:00Z")

        assertEquals(null, usageWindowElapsedFraction(window("unknown", null), now))
        assertEquals(null, usageWindowElapsedFraction(window("not running", 300), now))
        assertEquals(
            null,
            usageWindowElapsedFraction(window("unreadable", 300, "not a timestamp"), now),
        )
        assertEquals(null, usageWindowElapsedFraction(window("zero", 0), now))
    }

    private fun snapshot(
        machine: String,
        provider: String,
        limitId: String?,
        limitName: String? = null,
    ) =
        UsageSnapshot(
            provider = provider,
            machine = machine,
            machineName = machine,
            limitId = limitId,
            limitName = limitName,
            state = "ok",
            detail = null,
            windows = emptyList(),
        )

    private fun window(label: String, durationMinutes: Long?, resetsAt: String? = null) =
        UsageWindow(
            kind = "test",
            label = label,
            percent = 12.0,
            durationMinutes = durationMinutes,
            resetsAt = resetsAt,
            active = false,
        )
}