import Foundation
import Testing
@testable import Voice

@MainActor
struct TranscriptDedupeTests {
    private final class ClockBox {
        var time: Date
        init(time: Date) { self.time = time }
    }

    /// Returns a handler wired to a shared clock box, plus the box itself so
    /// tests can advance time deterministically.
    private func freshHandler() -> (handler: TranscriptHandler, clock: ClockBox) {
        // Isolate from any persisted entries left over from other runs.
        UserDefaults.standard.removeObject(forKey: TranscriptHistory.key)
        let history = TranscriptHistory()
        let handler = TranscriptHandler(history: history)
        let box = ClockBox(time: Date(timeIntervalSince1970: 1_000_000))
        handler.now = { box.time }
        return (handler, box)
    }

    private func advance(_ box: ClockBox, _ seconds: TimeInterval) {
        box.time = box.time.addingTimeInterval(seconds)
    }

    // MARK: Cross-source dedupe (opposite source within window)

    @Test("primary final then identical data final is suppressed (primary→data)")
    func primaryThenDataSuppressed() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .agent, text: "good morning", isFinal: true)
        #expect(handler.events.count == 1)

        // Data topic delivers the same final within the window → suppressed.
        handler.receiveDataTranscript(role: .agent, text: "good morning")
        #expect(handler.events.count == 1)
        #expect(handler.events[0].isFinal)
        #expect(handler.events[0].text == "good morning")
    }

    @Test("data final then identical primary final is suppressed (data→primary)")
    func dataThenPrimarySuppressed() {
        let (handler, _) = freshHandler()
        handler.receiveDataTranscript(role: .agent, text: "good morning")
        #expect(handler.events.count == 1)

        // Primary transcription delivers the same final within the window → suppressed.
        handler.receiveSegment(id: "seg-1", role: .agent, text: "good morning", isFinal: true)
        #expect(handler.events.count == 1)
        #expect(handler.events[0].isFinal)
        #expect(handler.events[0].text == "good morning")
    }

    // MARK: Same-source repeats are never suppressed

    @Test("same-source primary repeat within window is NOT suppressed")
    func sameSourcePrimaryRepeatAllowed() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .user, text: "hello", isFinal: true)
        #expect(handler.events.count == 1)

        // Same source (primary), same text, within window → allowed.
        handler.receiveSegment(id: "seg-2", role: .user, text: "hello", isFinal: true)
        #expect(handler.events.count == 2)
    }

    @Test("same-source data repeat within window is NOT suppressed")
    func sameSourceDataRepeatAllowed() {
        let (handler, _) = freshHandler()
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 1)

        // Same source (data), same text, within window → allowed.
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 2)
    }

    // MARK: Window expiry

    @Test("opposite-source final after window expiry is NOT suppressed")
    func oppositeSourceAfterWindowAllowed() {
        let (handler, clock) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .agent, text: "good morning", isFinal: true)
        #expect(handler.events.count == 1)

        // Advance past the 5-second dedupe window.
        advance(clock, 6)

        // Data topic delivers the same final after the window → allowed.
        handler.receiveDataTranscript(role: .agent, text: "good morning")
        #expect(handler.events.count == 2)
    }

    @Test("opposite-source final exactly at window boundary is NOT suppressed")
    func oppositeSourceAtBoundaryAllowed() {
        let (handler, clock) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .agent, text: "good morning", isFinal: true)

        // Advance exactly to the window boundary (5.0s). The check is
        // `timeIntervalSince < dedupeWindow`, so at exactly 5.0 it's NOT suppressed.
        advance(clock, 5.0)
        handler.receiveDataTranscript(role: .agent, text: "good morning")
        #expect(handler.events.count == 2)
    }

    @Test("opposite-source final just before window boundary is suppressed")
    func oppositeSourceJustBeforeBoundarySuppressed() {
        let (handler, clock) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .agent, text: "good morning", isFinal: true)

        // Advance to 4.9s — still within the window.
        advance(clock, 4.9)
        handler.receiveDataTranscript(role: .agent, text: "good morning")
        #expect(handler.events.count == 1)
    }

    // MARK: Interleaved roles

    @Test("interleaved roles do not interfere with cross-source dedupe")
    func interleavedRolesDedupe() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .user, text: "hi there", isFinal: false)
        handler.receiveDataTranscript(role: .agent, text: "hello")
        handler.receiveDataTranscript(role: .user, text: "hi there")

        // User partial replaced in place; agent final appended. Two events total.
        #expect(handler.events.count == 2)
        #expect(handler.events[0].isFinal)
        #expect(handler.events[0].text == "hi there")
        #expect(handler.events[1].isFinal)
        #expect(handler.events[1].text == "hello")
    }

    // MARK: Partial replacement

    @Test("data final matching open partial replaces it instead of duplicating")
    func dataFinalReplacesMatchingPartial() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .user, text: "hello world", isFinal: false)
        handler.receiveDataTranscript(role: .user, text: "hello world")

        #expect(handler.events.count == 1)
        #expect(handler.events[0].isFinal)
        #expect(handler.events[0].id == "seg-1")
    }

    @Test("data final with differing open partial replaces the partial in place")
    func differentPartialReplaced() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .user, text: "first utterance", isFinal: false)
        handler.receiveDataTranscript(role: .user, text: "second utterance")

        #expect(handler.events.count == 1)
        #expect(handler.events[0].isFinal)
        #expect(handler.events[0].text == "second utterance")
    }

    @Test("data final with no open partial appends a new final row")
    func dataFinalWithoutPartialAppends() {
        let (handler, _) = freshHandler()
        handler.receiveDataTranscript(role: .agent, text: "surprise final")

        #expect(handler.events.count == 1)
        #expect(handler.events[0].isFinal)
        #expect(handler.events[0].text == "surprise final")
    }

    // MARK: Max events trimming

    @Test("canonical collection trims to max 50 finals")
    func trimsToMaxEvents() {
        let (handler, _) = freshHandler()
        // Add 55 distinct finals (different text so no dedupe).
        for i in 0..<55 {
            handler.receiveSegment(id: "seg-\(i)", role: .agent, text: "utterance \(i)", isFinal: true)
        }
        #expect(handler.events.count == TranscriptHandler.maxEvents)
        // The oldest finals are dropped; the newest remain.
        #expect(handler.events.last?.text == "utterance 54")
    }

    // MARK: Clear

    @Test("clear removes events, dedupe state, and persistence")
    func clearResetsState() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .user, text: "test", isFinal: true)
        #expect(handler.events.count == 1)

        handler.clearAll()
        #expect(handler.events.isEmpty)

        // After clear, the same text can be recorded again (dedupe state reset).
        handler.receiveSegment(id: "seg-2", role: .user, text: "test", isFinal: true)
        #expect(handler.events.count == 1)
    }

    // MARK: Restoration from persisted history

    @Test("handler initializes canonical events from persisted history")
    func restoresFromHistory() {
        UserDefaults.standard.removeObject(forKey: TranscriptHistory.key)
        let history = TranscriptHistory()
        // Simulate a prior session's persisted finals.
        history.sync(finals: [
            (role: "user", text: "old question", timestamp: Date(timeIntervalSince1970: 900_000)),
            (role: "agent", text: "old answer", timestamp: Date(timeIntervalSince1970: 900_005)),
        ])

        let handler = TranscriptHandler(history: history)
        #expect(handler.events.count == 2)
        #expect(handler.events[0].text == "old question")
        #expect(handler.events[0].role == .user)
        #expect(handler.events[1].text == "old answer")
        #expect(handler.events[1].role == .agent)

        // A new live event appends after the restored entries.
        handler.receiveSegment(id: "seg-1", role: .user, text: "new question", isFinal: true)
        #expect(handler.events.count == 3)
        #expect(handler.events.last?.text == "new question")
    }

    // MARK: Live append after restoration

    @Test("live finals append after restored entries in canonical collection")
    func liveAppendAfterRestore() {
        UserDefaults.standard.removeObject(forKey: TranscriptHistory.key)
        let history = TranscriptHistory()
        history.sync(finals: [
            (role: "agent", text: "restored line", timestamp: Date(timeIntervalSince1970: 800_000)),
        ])

        let handler = TranscriptHandler(history: history)
        #expect(handler.events.count == 1)

        // Live partial then final.
        handler.receiveSegment(id: "seg-1", role: .user, text: "live partial", isFinal: false)
        #expect(handler.events.count == 2)
        handler.receiveSegment(id: "seg-1", role: .user, text: "live final", isFinal: true)
        #expect(handler.events.count == 2)
        #expect(handler.events.last?.text == "live final")
        #expect(handler.events.last?.isFinal == true)
    }

    // MARK: Persistence sync

    @Test("persistence mirrors canonical finals after each change")
    func persistenceMirrorsCanonical() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .user, text: "persist me", isFinal: true)

        // The history store should now contain exactly the canonical finals.
        #expect(handler.history.entries.count == 1)
        #expect(handler.history.entries[0].text == "persist me")
        #expect(handler.history.entries[0].role == "user")
    }

    @Test("cross-source dedupe does not drop the row from persistence")
    func dedupeDoesNotDropPersistence() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .agent, text: "deduped line", isFinal: true)
        // Data copy is suppressed — still one canonical event.
        handler.receiveDataTranscript(role: .agent, text: "deduped line")

        #expect(handler.events.count == 1)
        #expect(handler.history.entries.count == 1)
    }

    // MARK: Consume-on-suppress (Iteration 06 Item 2)

    @Test("primary final, data duplicate suppressed, second data final with same text accepted")
    func consumeOnSuppressAllowsSecondSameSource() {
        let (handler, _) = freshHandler()
        // Step 1: Primary delivers "hello".
        handler.receiveSegment(id: "seg-1", role: .user, text: "hello", isFinal: true)
        #expect(handler.events.count == 1)

        // Step 2: Data delivers the same "hello" within window → suppressed.
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 1)

        // Step 3: Data delivers a *second* legitimate "hello" (same source as
        // step 2). The consume-on-suppress should have updated the record to
        // .data, so this same-source repeat is NOT suppressed.
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 2)
    }

    @Test("data final, primary duplicate suppressed, second primary final with same text accepted")
    func consumeOnSuppressAllowsSecondPrimary() {
        let (handler, _) = freshHandler()
        // Step 1: Data delivers "world".
        handler.receiveDataTranscript(role: .agent, text: "world")
        #expect(handler.events.count == 1)

        // Step 2: Primary delivers the same "world" within window → suppressed.
        handler.receiveSegment(id: "seg-1", role: .agent, text: "world", isFinal: true)
        #expect(handler.events.count == 1)

        // Step 3: Primary delivers a *second* legitimate "world" (same source
        // as step 2). The consume-on-suppress should have updated the record to
        // .primary, so this same-source repeat is NOT suppressed.
        handler.receiveSegment(id: "seg-2", role: .agent, text: "world", isFinal: true)
        #expect(handler.events.count == 2)
    }

    @Test("same-source immediate repeats still accepted after consume")
    func sameSourceRepeatsAfterConsume() {
        let (handler, _) = freshHandler()
        // Primary "hi" → recorded as .primary.
        handler.receiveSegment(id: "seg-1", role: .user, text: "hi", isFinal: true)
        #expect(handler.events.count == 1)

        // Data "hi" → suppressed (opposite source), record consumed (removed).
        handler.receiveDataTranscript(role: .user, text: "hi")
        #expect(handler.events.count == 1)

        // Primary "hi" again → no record exists (was consumed), so this is a
        // new pair and is accepted.
        handler.receiveSegment(id: "seg-2", role: .user, text: "hi", isFinal: true)
        #expect(handler.events.count == 2)

        // Data "hi" again → suppressed (opposite source of the new record).
        handler.receiveDataTranscript(role: .user, text: "hi")
        #expect(handler.events.count == 2)
    }

    @Test("persistence remains exact after consume-on-suppress")
    func persistenceExactAfterConsume() {
        let (handler, _) = freshHandler()
        handler.receiveSegment(id: "seg-1", role: .user, text: "exact", isFinal: true)
        // Data duplicate suppressed.
        handler.receiveDataTranscript(role: .user, text: "exact")
        #expect(handler.events.count == 1)
        #expect(handler.history.entries.count == 1)

        // Second data final accepted.
        handler.receiveDataTranscript(role: .user, text: "exact")
        #expect(handler.events.count == 2)
        #expect(handler.history.entries.count == 2)
    }

    // MARK: Session start preserves history (Iteration 06 Item 1)

    @Test("starting a new session preserves restored history in canonical collection")
    func newSessionPreservesHistory() {
        UserDefaults.standard.removeObject(forKey: TranscriptHistory.key)
        let history = TranscriptHistory()
        history.sync(finals: [
            (role: "user", text: "prior question", timestamp: Date(timeIntervalSince1970: 800_000)),
            (role: "agent", text: "prior answer", timestamp: Date(timeIntervalSince1970: 800_005)),
        ])

        // Simulate what happens when a new VoiceSession is created: the handler
        // initializes from persisted history. Starting a session does NOT call
        // clearAll() — it preserves the restored entries.
        let handler = TranscriptHandler(history: history)
        #expect(handler.events.count == 2)
        #expect(handler.events[0].text == "prior question")
        #expect(handler.events[1].text == "prior answer")

        // A new live event appends after the restored entries.
        handler.receiveSegment(id: "seg-1", role: .user, text: "new utterance", isFinal: true)
        #expect(handler.events.count == 3)
        #expect(handler.events[0].text == "prior question")
        #expect(handler.events.last?.text == "new utterance")
    }

    // MARK: Repeated source pairs (Iteration 07 Item 3)

    @Test("P1,D1,P2,D2 produces exactly two canonical and persisted rows")
    func primaryDataPrimaryDataPairs() {
        let (handler, _) = freshHandler()
        // P1: Primary delivers "hello".
        handler.receiveSegment(id: "seg-p1", role: .user, text: "hello", isFinal: true)
        #expect(handler.events.count == 1)

        // D1: Data delivers the same "hello" → suppressed (opposite source), record consumed.
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 1)

        // P2: Primary delivers a *second* legitimate "hello". No record exists
        // (was consumed by D1 suppression), so this is accepted as a new pair.
        handler.receiveSegment(id: "seg-p2", role: .user, text: "hello", isFinal: true)
        #expect(handler.events.count == 2)

        // D2: Data delivers the same "hello" again → suppressed (opposite source of P2).
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 2)

        // Persistence mirrors the canonical collection exactly.
        #expect(handler.history.entries.count == 2)
    }

    @Test("D1,P1,D2,P2 produces exactly two canonical and persisted rows")
    func dataPrimaryDataPrimaryPairs() {
        let (handler, _) = freshHandler()
        // D1: Data delivers "hello".
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 1)

        // P1: Primary delivers the same "hello" → suppressed (opposite source), record consumed.
        handler.receiveSegment(id: "seg-p1", role: .user, text: "hello", isFinal: true)
        #expect(handler.events.count == 1)

        // D2: Data delivers a *second* legitimate "hello". No record exists
        // (was consumed by P1 suppression), so this is accepted as a new pair.
        handler.receiveDataTranscript(role: .user, text: "hello")
        #expect(handler.events.count == 2)

        // P2: Primary delivers the same "hello" again → suppressed (opposite source of D2).
        handler.receiveSegment(id: "seg-p2", role: .user, text: "hello", isFinal: true)
        #expect(handler.events.count == 2)

        // Persistence mirrors the canonical collection exactly.
        #expect(handler.history.entries.count == 2)
    }
}