fix(app): remove some dangerous reverse()s (#16591)

There weer a couple command texts that were doing a `.reverse()` of the
commands array. This is O(N) which is gross and also might be cached
which would cause bugs, so replace it with some uses of findLast() that
definitely weren't inspired by wanting to do some fun typing exercises.

## testing
- [x] tests pass, really

app/src/local-resources/commands/hooks/useCommandTextString/utils/getFinalLabwareLocation.ts

@@ -1,4 +1,25 @@
-import type { LabwareLocation, RunTimeCommand } from '@opentrons/shared-data'
+import type {
+  LabwareLocation,
+  RunTimeCommand,
+  LoadLabwareRunTimeCommand,
+  MoveLabwareRunTimeCommand,
+} from '@opentrons/shared-data'
+
+const findLastAt = <T, U extends T = T>(
+  arr: readonly T[],
+  pred: ((el: T) => boolean) | ((el: T) => el is U)
+): [U, number] | [undefined, -1] => {
+  let arrayLoc = -1
+  const lastEl = arr.findLast((el: T, idx: number): el is U => {
+    arrayLoc = idx
+    return pred(el)
+  })
+  if (lastEl === undefined) {
+    return [undefined, -1]
+  } else {
+    return [lastEl, arrayLoc]
+  }
+}
 
 /**
  * given a list of commands and a labwareId, calculate the resulting location
@@ -11,15 +32,22 @@ export function getFinalLabwareLocation(
   labwareId: string,
   commands: RunTimeCommand[]
 ): LabwareLocation | null {
-  for (const c of commands.reverse()) {
-    if (c.commandType === 'loadLabware' && c.result?.labwareId === labwareId) {
-      return c.params.location
-    } else if (
-      c.commandType === 'moveLabware' &&
-      c.params.labwareId === labwareId
-    ) {
-      return c.params.newLocation
-    }
+  const [lastMove, lastMoveIndex] = findLastAt(
+    commands,
+    (c: RunTimeCommand): c is MoveLabwareRunTimeCommand =>
+      c.commandType === 'moveLabware' && c.params.labwareId === labwareId
+  )
+
+  const [lastLoad, lastLoadIndex] = findLastAt(
+    commands,
+    (c: RunTimeCommand): c is LoadLabwareRunTimeCommand =>
+      c.commandType === 'loadLabware' && c.result?.labwareId === labwareId
+  )
+  if (lastMoveIndex > lastLoadIndex) {
+    return lastMove?.params?.newLocation ?? null
+  } else if (lastLoadIndex > lastMoveIndex) {
+    return lastLoad?.params?.location ?? null
+  } else {
+    return null
   }
-  return null
 }

app/src/local-resources/commands/hooks/useCommandTextString/utils/getWellRange.ts

@@ -1,5 +1,42 @@
 import { getPipetteNameSpecs } from '@opentrons/shared-data'
-import type { PipetteName, RunTimeCommand } from '@opentrons/shared-data'
+import type {
+  PipetteName,
+  RunTimeCommand,
+  ConfigureNozzleLayoutRunTimeCommand,
+} from '@opentrons/shared-data'
+
+const usedChannelsFromCommand = (
+  command: ConfigureNozzleLayoutRunTimeCommand | undefined,
+  defaultChannels: number
+): number =>
+  command?.params?.configurationParams?.style === 'SINGLE'
+    ? 1
+    : command?.params?.configurationParams?.style === 'COLUMN'
+    ? 8
+    : defaultChannels
+
+const usedChannelsForPipette = (
+  pipetteId: string,
+  commands: RunTimeCommand[],
+  defaultChannels: number
+): number =>
+  usedChannelsFromCommand(
+    commands.findLast(
+      (c: RunTimeCommand): c is ConfigureNozzleLayoutRunTimeCommand =>
+        c.commandType === 'configureNozzleLayout' &&
+        c.params?.pipetteId === pipetteId
+    ),
+    defaultChannels
+  )
+
+const usedChannels = (
+  pipetteId: string,
+  commands: RunTimeCommand[],
+  pipetteChannels: number
+): number =>
+  pipetteChannels === 96
+    ? usedChannelsForPipette(pipetteId, commands, pipetteChannels)
+    : pipetteChannels
 
 /**
  * @param pipetteName name of pipette being used
@@ -16,26 +53,10 @@ export function getWellRange(
   const pipetteChannels = pipetteName
     ? getPipetteNameSpecs(pipetteName)?.channels ?? 1
     : 1
-  let usedChannels = pipetteChannels
-  if (pipetteChannels === 96) {
-    for (const c of commands.reverse()) {
-      if (
-        c.commandType === 'configureNozzleLayout' &&
-        c.params?.pipetteId === pipetteId
-      ) {
-        // TODO(sb, 11/9/23): add support for quadrant and row configurations when needed
-        if (c.params.configurationParams.style === 'SINGLE') {
-          usedChannels = 1
-        } else if (c.params.configurationParams.style === 'COLUMN') {
-          usedChannels = 8
-        }
-        break
-      }
-    }
-  }
-  if (usedChannels === 96) {
+  const channelCount = usedChannels(pipetteId, commands, pipetteChannels)
+  if (channelCount === 96) {
     return 'A1 - H12'
-  } else if (usedChannels === 8) {
+  } else if (channelCount === 8) {
     const column = wellName.substr(1)
     return `A${column} - H${column}`
   }