epic-12: after epic audit and init commit

core/sessions/build.gradle

@@ -0,0 +1,10 @@
+plugins {
+    id 'java-library'
+    id 'org.jetbrains.kotlin.jvm'
+    id 'org.jetbrains.kotlin.plugin.serialization'
+}
+
+dependencies {
+    implementation(project(":core:events"))
+    testImplementation(testFixtures(project(":testing:contracts")))
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/ApprovalMode.kt

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+package com.correx.core.sessions
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+enum class ApprovalMode {
+    DENY,
+    PROMPT,
+    AUTO,
+    YOLO
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/DefaultSessionReducer.kt

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+package com.correx.core.sessions
+
+import com.correx.core.events.events.SessionCompletedEvent
+import com.correx.core.events.events.SessionFailedEvent
+import com.correx.core.events.events.SessionPausedEvent
+import com.correx.core.events.events.SessionResumedEvent
+import com.correx.core.events.events.SessionStartedEvent
+import com.correx.core.events.events.StageCompletedEvent
+import com.correx.core.events.events.StageFailedEvent
+import com.correx.core.events.events.StageStartedEvent
+import com.correx.core.events.events.StoredEvent
+import com.correx.core.events.events.TransitionExecutedEvent
+
+class DefaultSessionReducer : SessionReducer {
+
+    override fun reduce(
+        state: SessionState,
+        event: StoredEvent
+    ): SessionState {
+
+        val payload = event.payload
+
+        val newStatus = when (payload) {
+
+            is SessionStartedEvent ->
+                SessionStatus.ACTIVE
+
+            is SessionPausedEvent ->
+                SessionStatus.PAUSED
+
+            is SessionResumedEvent ->
+                SessionStatus.ACTIVE
+
+            is SessionCompletedEvent ->
+                SessionStatus.COMPLETED
+
+            is SessionFailedEvent,
+            is StageFailedEvent ->
+                SessionStatus.FAILED
+
+            is StageStartedEvent,
+            is StageCompletedEvent,
+            is TransitionExecutedEvent ->
+                SessionStatus.ACTIVE
+
+            else ->
+                state.status
+        }
+
+        val createdAt = state.createdAt
+            ?: event.metadata.timestamp
+
+        return state.copy(
+            status = newStatus,
+            createdAt = createdAt,
+            updatedAt = event.metadata.timestamp
+        )
+    }
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/DefaultSessionRepository.kt

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+package com.correx.core.sessions
+
+import com.correx.core.events.types.SessionId
+import com.correx.core.sessions.projections.replay.EventReplayer
+
+class DefaultSessionRepository(
+    private val replayer: EventReplayer<SessionState>
+) {
+
+    fun getSession(sessionId: SessionId): Session = rebuild(sessionId)
+
+    fun rebuild(sessionId: SessionId): Session = Session(
+        sessionId,
+        replayer.rebuild(sessionId),
+    )
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/Session.kt

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+package com.correx.core.sessions
+
+import com.correx.core.events.types.SessionId
+
+data class Session(
+    val sessionId: SessionId,
+    val state: SessionState,
+)

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionCounterProjection.kt

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+package com.correx.core.sessions
+
+import com.correx.core.events.events.StoredEvent
+import com.correx.core.sessions.projections.Projection
+
+class SessionCounterProjection(
+    private val sessionId: String
+) : Projection<SessionCounterState> {
+
+    override fun initial(): SessionCounterState =
+        SessionCounterState(sessionId, 0)
+
+    override fun apply(
+        state: SessionCounterState,
+        event: StoredEvent
+    ): SessionCounterState {
+        return state.copy(count = state.count + 1)
+    }
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionCounterState.kt

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+package com.correx.core.sessions
+
+data class SessionCounterState(
+    val sessionId: String,
+    val count: Int
+)

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionProjector.kt

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+package com.correx.core.sessions
+
+import com.correx.core.events.events.StoredEvent
+import com.correx.core.sessions.projections.Projection
+
+class SessionProjector(
+    private val reducer: SessionReducer
+) : Projection<SessionState> {
+
+    override fun initial(): SessionState =
+        SessionState(
+            status = SessionStatus.CREATED
+        )
+
+    override fun apply(
+        state: SessionState,
+        event: StoredEvent
+    ): SessionState = reducer.reduce(state, event)
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionReducer.kt

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+package com.correx.core.sessions
+
+import com.correx.core.events.events.StoredEvent
+
+interface SessionReducer {
+    fun reduce(
+        state: SessionState,
+        event: StoredEvent
+    ): SessionState
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionState.kt

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+package com.correx.core.sessions
+
+import kotlinx.datetime.Instant
+
+data class SessionState(
+    val status: SessionStatus,
+    val createdAt: Instant? = null,
+    val updatedAt: Instant? = null,
+    val invalidTransitions: Int = 0,
+)

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionStatus.kt

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+package com.correx.core.sessions
+
+enum class SessionStatus {
+    CREATED,
+    ACTIVE,
+    PAUSED,
+    COMPLETED,
+    FAILED,
+    ;
+}

core/sessions/src/main/kotlin/com/correx/core/sessions/TransitionResult.kt

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+package com.correx.core.sessions
+
+sealed interface TransitionResult {
+    data class Applied(val newState: SessionStatus) : TransitionResult
+    data object Rejected : TransitionResult
+}

core/sessions/src/test/kotlin/com/correx/core/sessions/projections/SessionCounterProjectionTest.kt

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+package com.correx.core.sessions.projections
+
+import com.correx.testing.contracts.fixtures.projections.CountingProjectionContractTest
+
+class SessionCounterProjectionTest : CountingProjectionContractTest()