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refactor(util): fix ScanStateReducer precedence cascade
The previous when cascade used the pattern REGEX.find(line)?.let { ...; null } != null -> return ... which always evaluated to false on both arms (the let returned null on match, and short-circuited to null on no-match), making the right-side return dead code. Every matching regex's let body ran and the function fell through to the trailing blocks, destroying the first-match-wins precedence the original parseScanLine early-returns guaranteed. Test case 13 (scanTotalsPreemptsActiveResolversOnSameLine) would have observed activeResolvers=5 instead of the expected 0. Rewrite using the idiomatic Option A shape: pre-compute the 6 early-return match results (scanMatch, activeMatch, totalActiveMatch, remainingMatch, syncedMtuMatch, testingMtu) before the when, let the when mutate scanStatus for the first matching arm only, then a single if (anyMatched) return short-circuits the trailing MTU-completed / Session-initialized / SESSION_INIT_BACKOFF blocks. The 4 non-returning pre blocks (RESOLVER_ADDED, RESOLVER_REMOVED, INDEXED_PROGRESS, TOTAL_CANDIDATES) stay before the cascade, unchanged. Hand-traced cases 9, 10, 12, 13 line-by-line against the original parseScanLine; all produce identical state.
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Lines changed: 36 additions & 43 deletions

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‎android/app/src/main/java/com/masterdns/vpn/util/ScanStateReducer.kt‎

Lines changed: 36 additions & 43 deletions
Original file line numberDiff line numberDiff line change
@@ -86,14 +86,24 @@ internal object ScanStateReducer {
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}
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}
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// ponytail: when-cascade with explicit `return` mirrors the original
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// parseScanLine early-returns so a line matching multiple patterns
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// only fires the first match (e.g. SCAN_TOTALS preempts ACTIVE_RESOLVERS).
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// ponytail: pre-compute the 6 early-return matches, then a when cascade
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// mutates scanStatus for the first matching arm only, then a single
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// guarded return short-circuits the trailing blocks. Mirrors the
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// original parseScanLine early-returns (SCAN_TOTALS, ACTIVE_RESOLVERS,
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// TOTAL_ACTIVE, REMAINING, SYNCED_MTU, "Testing MTU sizes") so a line
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// matching multiple patterns only fires the first match.
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val scanMatch = SCAN_TOTALS_REGEX.find(line)
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val activeMatch = ACTIVE_RESOLVERS_REGEX.find(line)
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val totalActiveMatch = TOTAL_ACTIVE_REGEX.find(line)
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val remainingMatch = REMAINING_REGEX.find(line)
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val syncedMtuMatch = SYNCED_MTU_REGEX.find(line)
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val testingMtu = line.contains("Testing MTU sizes", ignoreCase = true)
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when {
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SCAN_TOTALS_REGEX.find(line)?.let { match ->
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val resolver = match.groupValues[1]
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val valid = match.groupValues[2].toIntOrNull() ?: scanStatus.validCount
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val rejected = match.groupValues[3].toIntOrNull() ?: scanStatus.rejectedCount
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scanMatch != null -> {
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val resolver = scanMatch!!.groupValues[1]
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val valid = scanMatch!!.groupValues[2].toIntOrNull() ?: scanStatus.validCount
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val rejected = scanMatch!!.groupValues[3].toIntOrNull() ?: scanStatus.rejectedCount
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val decision = when {
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line.contains("Accepted", ignoreCase = true) -> "Accepted"
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line.contains("Rejected", ignoreCase = true) -> "Rejected"
@@ -106,44 +116,27 @@ internal object ScanStateReducer {
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validCount = valid,
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rejectedCount = rejected
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)
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null
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} != null -> return ScanStateBundle(scanStatus, activeResolvers, connectionWarning)
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ACTIVE_RESOLVERS_REGEX.find(line)?.let { match ->
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scanStatus = scanStatus.copy(
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activeResolvers = match.groupValues[1].toIntOrNull() ?: scanStatus.activeResolvers
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)
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null
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} != null -> return ScanStateBundle(scanStatus, activeResolvers, connectionWarning)
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TOTAL_ACTIVE_REGEX.find(line)?.let { match ->
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scanStatus = scanStatus.copy(
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activeResolvers = match.groupValues[1].toIntOrNull() ?: scanStatus.activeResolvers
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)
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null
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} != null -> return ScanStateBundle(scanStatus, activeResolvers, connectionWarning)
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REMAINING_REGEX.find(line)?.let { match ->
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scanStatus = scanStatus.copy(
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activeResolvers = match.groupValues[1].toIntOrNull() ?: scanStatus.activeResolvers
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)
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null
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} != null -> return ScanStateBundle(scanStatus, activeResolvers, connectionWarning)
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SYNCED_MTU_REGEX.find(line)?.let { match ->
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scanStatus = scanStatus.copy(
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syncedUploadMtu = match.groupValues[1].toIntOrNull() ?: 0,
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syncedDownloadMtu = match.groupValues[2].toIntOrNull() ?: 0
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)
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null
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} != null -> return ScanStateBundle(scanStatus, activeResolvers, connectionWarning)
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line.contains("Testing MTU sizes", ignoreCase = true) -> {
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scanStatus = scanStatus.copy(scanning = true)
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return ScanStateBundle(scanStatus, activeResolvers, connectionWarning)
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}
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activeMatch != null -> scanStatus = scanStatus.copy(
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activeResolvers = activeMatch!!.groupValues[1].toIntOrNull() ?: scanStatus.activeResolvers
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)
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totalActiveMatch != null -> scanStatus = scanStatus.copy(
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activeResolvers = totalActiveMatch!!.groupValues[1].toIntOrNull() ?: scanStatus.activeResolvers
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)
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remainingMatch != null -> scanStatus = scanStatus.copy(
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activeResolvers = remainingMatch!!.groupValues[1].toIntOrNull() ?: scanStatus.activeResolvers
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)
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syncedMtuMatch != null -> scanStatus = scanStatus.copy(
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syncedUploadMtu = syncedMtuMatch!!.groupValues[1].toIntOrNull() ?: 0,
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syncedDownloadMtu = syncedMtuMatch!!.groupValues[2].toIntOrNull() ?: 0
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)
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testingMtu -> scanStatus = scanStatus.copy(scanning = true)
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}
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else -> Unit
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if (scanMatch != null || activeMatch != null || totalActiveMatch != null ||
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remainingMatch != null || syncedMtuMatch != null || testingMtu
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) {
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return ScanStateBundle(scanStatus, activeResolvers, connectionWarning)
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}
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if (line.contains("MTU Testing Completed", ignoreCase = true) ||

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