From 4e45827826b52f812ce5115dc1d0ed8f23587e7a Mon Sep 17 00:00:00 2001
From: Hannah Purcell <hpurcell@mbta.com>
Date: Tue, 10 Dec 2024 19:07:25 -0500
Subject: [PATCH] feat: Frontend hook for accessing detours channel

---
 assets/src/hooks/useDetours.ts | 244 +++++++++++++++++++++++++++++++++
 1 file changed, 244 insertions(+)
 create mode 100644 assets/src/hooks/useDetours.ts

diff --git a/assets/src/hooks/useDetours.ts b/assets/src/hooks/useDetours.ts
new file mode 100644
index 000000000..c3e89f482
--- /dev/null
+++ b/assets/src/hooks/useDetours.ts
@@ -0,0 +1,244 @@
+import { Channel, Socket } from "phoenix"
+import { SimpleDetour } from "../models/detoursList"
+import { useEffect, useState } from "react"
+import { reload } from "../models/browser"
+import { userUuid } from "../util/userUuid"
+import { RouteId } from "../schedule"
+
+interface DetoursMap {
+  [key: number]: SimpleDetour
+}
+
+const subscribe = (
+  socket: Socket,
+  topic: string,
+  initializeChannel: React.Dispatch<React.SetStateAction<DetoursMap>>,
+  handleDrafted: ((data: SimpleDetour) => void) | undefined,
+  handleActivated: ((data: SimpleDetour) => void) | undefined,
+  handleDeactivated: ((data: SimpleDetour) => void) | undefined
+): Channel => {
+  const channel = socket.channel(topic)
+
+  handleDrafted &&
+    channel.on("drafted", ({ data: data }) => handleDrafted(data))
+  handleActivated &&
+    channel.on("activated", ({ data: data }) => handleActivated(data))
+  handleDeactivated &&
+    channel.on("deactivated", ({ data: data }) => handleDeactivated(data))
+  channel.on("auth_expired", reload)
+
+  channel
+    .join()
+    .receive("ok", ({ data: data }: { data: SimpleDetour[] }) => {
+      const detoursMap = data.reduce(
+        (acc, detour) => ({ ...acc, [detour.id]: detour }),
+        {}
+      )
+      initializeChannel(detoursMap)
+    })
+
+    .receive("error", ({ reason }) => {
+      if (reason === "not_authenticated") {
+        reload()
+      } else {
+        // eslint-disable-next-line no-console
+        console.error(`joining topic ${topic} failed`, reason)
+      }
+    })
+    .receive("timeout", reload)
+
+  return channel
+}
+
+// This is to refresh the Detours List page. We need all active detours
+export const useActiveDetours = (socket: Socket | undefined) => {
+  const topic = "detours:active"
+  const [activeDetours, setActiveDetours] = useState<DetoursMap>({})
+
+  const handleActivated = (data: SimpleDetour) => {
+    setActiveDetours((activeDetours) => ({ ...activeDetours, [data.id]: data }))
+  }
+
+  const handleDeactivated = (data: SimpleDetour) => {
+    setActiveDetours((activeDetours) => {
+      delete activeDetours[data.id]
+      return activeDetours
+    })
+  }
+
+  useEffect(() => {
+    let channel: Channel | undefined
+    if (socket) {
+      channel = subscribe(
+        socket,
+        topic,
+        setActiveDetours,
+        undefined,
+        handleActivated,
+        handleDeactivated
+      )
+    }
+
+    return () => {
+      if (channel !== undefined) {
+        channel.leave()
+        channel = undefined
+      }
+    }
+  }, [socket])
+  return activeDetours
+}
+
+// This is to refresh the Detours List page, past detours section
+export const usePastDetours = (socket: Socket | undefined) => {
+  const topic = "detours:past"
+  const [pastDetours, setPastDetours] = useState<DetoursMap>({})
+
+  const handleDeactivated = (data: SimpleDetour) => {
+    setPastDetours((pastDetours) => ({ ...pastDetours, [data.id]: data }))
+  }
+
+  useEffect(() => {
+    let channel: Channel | undefined
+    if (socket) {
+      channel = subscribe(
+        socket,
+        topic,
+        setPastDetours,
+        undefined,
+        undefined,
+        handleDeactivated
+      )
+    }
+
+    return () => {
+      if (channel !== undefined) {
+        channel.leave()
+        channel = undefined
+      }
+    }
+  }, [socket])
+  return pastDetours
+}
+
+// This is to refresh the Detours List page, just the current user drafts
+export const useDraftDetours = (socket: Socket | undefined) => {
+  const topic = "detours:draft:" + userUuid()
+  const [draftDetours, setDraftDetours] = useState<DetoursMap>({})
+
+  const handleDrafted = (data: SimpleDetour) => {
+    setDraftDetours((draftDetours) => ({ ...draftDetours, [data.id]: data }))
+  }
+
+  const handleActivated = (data: SimpleDetour) => {
+    setDraftDetours((draftDetours) => {
+      delete draftDetours[data.id]
+      return draftDetours
+    })
+  }
+
+  useEffect(() => {
+    let channel: Channel | undefined
+    if (socket) {
+      channel = subscribe(
+        socket,
+        topic,
+        setDraftDetours,
+        handleDrafted,
+        handleActivated,
+        undefined
+      )
+    }
+
+    return () => {
+      if (channel !== undefined) {
+        channel.leave()
+        channel = undefined
+      }
+    }
+  }, [socket])
+  return draftDetours
+}
+
+interface DetoursMapByRoute {
+  [key: string]: DetoursMap
+}
+
+const subscribeByRoute = (
+  socket: Socket,
+  topic: string,
+  routeId: string,
+  setDetours: React.Dispatch<React.SetStateAction<DetoursMapByRoute>>
+): Channel => {
+  const channel = socket.channel(topic)
+
+  channel.on("activated", ({ data: data }) => {
+    setDetours((activeDetours) => ({
+      ...activeDetours,
+      [routeId]: { ...activeDetours[routeId], [data.id]: data },
+    }))
+  })
+  channel.on("deactivated", ({ data: data }) => {
+    setDetours((activeDetours) => {
+      delete activeDetours[routeId][data.id]
+      return activeDetours
+    })
+  })
+  channel.on("auth_expired", reload)
+
+  channel
+    .join()
+    .receive("ok", ({ data: data }: { data: SimpleDetour[] }) => {
+      const detoursMap = {
+        [routeId]: data.reduce(
+          (acc, detour) => ({ ...acc, [detour.id]: detour }),
+          {}
+        ),
+      }
+      setDetours(detoursMap)
+    })
+
+    .receive("error", ({ reason }) => {
+      if (reason === "not_authenticated") {
+        reload()
+      } else {
+        // eslint-disable-next-line no-console
+        console.error(`joining topic ${topic} failed`, reason)
+      }
+    })
+    .receive("timeout", reload)
+
+  return channel
+}
+
+// This is to refresh the Route Ladders
+export const useActiveDetoursByRoute = (
+  socket: Socket | undefined,
+  routeIds: RouteId[]
+) => {
+  const baseTopic = "detours:active:"
+  const [activeDetours, setActiveDetours] = useState<DetoursMapByRoute>({})
+
+  useEffect(() => {
+    let channel: Channel | undefined
+    if (socket) {
+      routeIds.forEach(
+        (routeId) =>
+          (channel = subscribeByRoute(
+            socket,
+            baseTopic,
+            routeId,
+            setActiveDetours
+          ))
+      )
+    }
+
+    return () => {
+      if (channel !== undefined) {
+        channel.leave()
+        channel = undefined
+      }
+    }
+  }, [socket])
+  return activeDetours
+}