{
  "name": "Weekly Matrix Coffee Groups",
  "nodes": [
    {
      "name": "Weekly trigger on monday1",
      "type": "n8n-nodes-base.cron",
      "position": [
        480,
        240
      ],
      "parameters": {
        "triggerTimes": {
          "item": [
            {
              "mode": "everyWeek",
              "weekday": "1",
              "hour": 10
            }
          ]
        }
      },
      "typeVersion": 1,
      "id": "matrix-weekly-coffee-groups-0"
    },
    {
      "name": "Configure the Matrix rooms",
      "type": "n8n-nodes-base.code",
      "typeVersion": 2,
      "parameters": {
        "mode": "runOnceForAllItems",
        "jsCode": "function config({homeserver,memberRoom,announcementRoom}){if(typeof homeserver!=='string'||homeserver.includes('YOUR_')||!/^https:\\/\\/[^/?#@\\s]+(?:\\/[^?#\\s]*)?$/i.test(homeserver))throw Error('Configure an HTTPS Matrix homeserver without credentials');for(const room of [memberRoom,announcementRoom])if(typeof room!=='string'||room.includes('YOUR_')||!/^![^\\s/:]+:[^\\s/]+$/.test(room))throw Error('Configure both Matrix room IDs');const base=homeserver.replace(/\\/+$/,''),prefix=base+'/_matrix/client/v3/rooms/',txn=Date.now().toString(36)+'-'+Math.random().toString(36).slice(2)+'-'+Math.random().toString(36).slice(2);return{base,memberRoom,announcementRoom,greetingUrl:prefix+encodeURIComponent(memberRoom)+'/send/m.room.message/'+txn,membersUrl:prefix+encodeURIComponent(memberRoom)+'/members',greeting:{msgtype:'m.text',body:\"👋 Happy Monday Groups for this week's virtual coffee are:\"}}}\n\nreturn [{json:config({homeserver:'https://YOUR_MATRIX_HOMESERVER',memberRoom:'!YOUR_MEMBER_ROOM:example.org',announcementRoom:'!YOUR_ANNOUNCEMENT_ROOM:example.org'})}];"
      },
      "id": "matrix-weekly-coffee-groups-1"
    },
    {
      "name": "Greetings",
      "type": "n8n-nodes-base.matrix",
      "position": [
        670,
        240
      ],
      "parameters": {
        "resource": "message",
        "operation": "create",
        "roomId": "={{ $json.memberRoom }}",
        "text": "👋 Happy Monday Groups for this week's virtual coffee are:",
        "messageType": "m.text",
        "messageFormat": "plain"
      },
      "typeVersion": 1,
      "id": "matrix-weekly-coffee-groups-2"
    },
    {
      "name": "Confirm the greeting",
      "type": "n8n-nodes-base.code",
      "typeVersion": 2,
      "parameters": {
        "mode": "runOnceForAllItems",
        "jsCode": "const body=$input.first().json;if(typeof body?.event_id!=='string'||!body.event_id)throw Error('Matrix did not confirm the greeting');return [{json:body}];"
      },
      "id": "matrix-weekly-coffee-groups-3"
    },
    {
      "name": "Read room membership events",
      "type": "n8n-nodes-base.httpRequest",
      "typeVersion": 4.2,
      "parameters": {
        "method": "GET",
        "url": "={{ $(\"Configure the Matrix rooms\").first().json.membersUrl }}",
        "authentication": "genericCredentialType",
        "genericAuthType": "httpHeaderAuth",
        "options": {
          "redirect": {
            "redirect": {
              "followRedirects": false
            }
          }
        }
      },
      "id": "matrix-weekly-coffee-groups-4"
    },
    {
      "name": "Shuffle and form coffee groups",
      "type": "n8n-nodes-base.code",
      "typeVersion": 2,
      "parameters": {
        "mode": "runOnceForAllItems",
        "jsCode": "function groups({body}){if(!Array.isArray(body?.chunk))throw Error('Matrix returned no member list');const users=body.chunk.map(e=>{if(e?.type!=='m.room.member'||typeof e.state_key!=='string'||!/^@[^\\s:]+:[^\\s]+$/.test(e.state_key))throw Error('Invalid Matrix member event');return e.state_key});if(new Set(users).size!==users.length)throw Error('Duplicate Matrix member');if(users.length<2)return{groups:[]};for(let n=users.length;n>0;n--){const j=Math.floor(Math.random()*n);[users[n-1],users[j]]=[users[j],users[n-1]]}const groups=[];for(let i=0;i<users.length;i+=3)groups.push(users.slice(i,i+3));if(groups.at(-1).length===1)groups.at(-1).push(groups.at(-2).shift());return{groups}}\n\nconst r=groups({body:$input.first().json});return r.groups.map(group=>({json:{text:'☀️ '+group.join(', ')}}));"
      },
      "id": "matrix-weekly-coffee-groups-5"
    },
    {
      "name": "Post groups one at a time",
      "type": "n8n-nodes-base.splitInBatches",
      "typeVersion": 3,
      "parameters": {
        "batchSize": 1,
        "options": {}
      },
      "id": "matrix-weekly-coffee-groups-6"
    },
    {
      "name": "Announce groups",
      "type": "n8n-nodes-base.matrix",
      "position": [
        1290,
        240
      ],
      "parameters": {
        "resource": "message",
        "operation": "create",
        "roomId": "={{ $(\"Configure the Matrix rooms\").first().json.announcementRoom }}",
        "text": "={{ $json.text }}",
        "messageType": "m.text",
        "messageFormat": "plain"
      },
      "typeVersion": 1,
      "id": "matrix-weekly-coffee-groups-7"
    },
    {
      "name": "Confirm the group messages",
      "type": "n8n-nodes-base.code",
      "typeVersion": 2,
      "parameters": {
        "mode": "runOnceForAllItems",
        "jsCode": "const items=$input.all();for(const item of items)if(typeof item.json.event_id!=='string'||!item.json.event_id)throw Error('Matrix did not confirm a group message');return items;"
      },
      "id": "matrix-weekly-coffee-groups-8"
    }
  ],
  "active": false,
  "settings": {
    "timezone": "UTC",
    "executionOrder": "v1"
  },
  "connections": {
    "Weekly trigger on monday1": {
      "main": [
        [
          {
            "node": "Configure the Matrix rooms",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Configure the Matrix rooms": {
      "main": [
        [
          {
            "node": "Greetings",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Greetings": {
      "main": [
        [
          {
            "node": "Confirm the greeting",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Confirm the greeting": {
      "main": [
        [
          {
            "node": "Read room membership events",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Read room membership events": {
      "main": [
        [
          {
            "node": "Shuffle and form coffee groups",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Shuffle and form coffee groups": {
      "main": [
        [
          {
            "node": "Post groups one at a time",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Announce groups": {
      "main": [
        [
          {
            "node": "Confirm the group messages",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Confirm the group messages": {
      "main": [
        [
          {
            "node": "Post groups one at a time",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Post groups one at a time": {
      "main": [
        [],
        [
          {
            "node": "Announce groups",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {}
}