dnscontrol/pkg/diff2/notes.txt

EXISTING:
  laba A 1.2.3.4      [0]
  laba MX 10 laba     [1]
  labc CNAME laba     [2]
  labe A 10.10.10.15  [3]
  labe A 10.10.10.16  [4]
  labe A 10.10.10.17  [5]
  labe A 10.10.10.18  [6]
  labg NS 10.10.10.15 [7]
  labg NS 10.10.10.16 [8]
  labg NS 10.10.10.17 [9]
  labg NS 10.10.10.18 [10]
  labh CNAME labd     [11]

DESIRED:
  laba A 1.2.3.4      [0']
  laba A 1.2.3.5      [1']
  laba MX 20 labb     [2']
  labe A 10.10.10.95  [3']
  labe A 10.10.10.96  [4']
  labe A 10.10.10.97  [5']
  labe A 10.10.10.98  [6']
  labf TXT "foo"      [7']
  labg NS 10.10.10.10 [8']
  labg NS 10.10.10.15 [9']
  labg NS 10.10.10.16 [10']
  labg NS 10.10.10.97 [11']
  labh A 1.2.3.4      [12']

ByRRSet:
  [] laba:A     CHANGE NewSet: { [0], [1'] } (ByRecords needs: Old [0] )
  [] laba:MX    CHANGE NewSet: { [2'] }  (ByLabel needs: Old: [2])
  [] labc:CNAME DELETE Old: { [2 ] }
  [] labe:A     CHANGE NewSet: { [3'], [4'], [5'], [6'] }
  [] labf:TXT   CHANGE NewSet: { [7'] }
  [] labg:NS    CHANGE NewSet: { [7] [8] [8'] [11'] }
  [] labh:CNAME DELETE Old { [11] }
  [] labh:A     CREATE NewSet: { [12'] }

ByRecord:
CREATE [1']
CHANGE [1] [2']
DELETE [2]
CHANGE [3] [3']
CHANGE [4] [4']
CHANGE [5] [5']
CHANGE [6] [6']
CREATE [7']
CREATE [8']
CHANGE [10] [11']
DELETE [11]
CREATE [12']


ByLabel: (take ByRRSet gather all CHANGES)
laba   CHANGE NewSet: { [0'], [1'], [2'] }
labc   DELETE Old: { [2] }
labe   CHANGE New: { [3'], [4'], [5'], [6'] }
labf   CREATE New: { [7'] }
labg   CHANGE NewSet: { [7] [8] [8'] [11'] }
labh   DELETE Old { [11] }
labh   CREATE NewSet: { [12'] }




By Record:

rewrite as triples:   FQDN+TYPE, TARGET, RC
byRecord:
  group-by key=FQDN+TYPE, use targets to make add/change/delete for each record.

byRSet:
  group-by key=FQDN+TYPE, use targets to make add/change/delete for each record.
     for each key:
        if both have this key:
            IF targets are the same, skip.
            Else generate CHANGE for KEY:
                New = Recs from desired.
                Msgs = The msgs from targetdiff(e.Recs, d.Recs)

byLabel:
  group-by key=FQDN, use type+targets to make add/change/delete for each record.


rewrite as triples:   FQDN {, TYPE, TARGET, RC

type CompareConfig struct {
  existing, desired models.Records
  ldata: []LabelConfig
}

type ByLabelConfig struct {
  label string
  tdata: []ByRTypeConfig
}

type ByRTypeConfig struct {
  rtype string
  existing: []TargetConfig
  desired: []TargetConfig
  existingRecs: []*models.RecordConfig
  desiredRecs: []*models.RecordConfig
}

type TargetConfig struct {
  compareable string
  rec *model.RecordConfig
}

func highest[S ~[]T, T any](s S) int {
    return len(s) - 1 
}

populate CompareConfig.
for rec := range desired {
  label = FILL
  rtype = FILL
  comp = FILL
  cc.labelMap[label] = &rc
  cc.keyMap[key] = &rc
  if not seen label:
     append cc.ldata ByLabelConfig{}
  labelIdx = last(cc.ldata)
  if not seen key:
     append cc.ldata[labelIdx].tdata ByRTypeConfig{}
     rtIdx = last(cc.ldata[labelIdx].tdata)
  cc.ldata[labelIdx].label = label
  cc.ldata[labelIdx].tdata[rtIdx].rtype = rtype
  cc.ldata[labelIdx].tdata[rtIdx].existing[append].comparable = comp
  cc.ldata[labelIdx].tdata[rtIdx].existing[append].rec = &rc
}

ByRSet:
func traverse(cc CompareConfig) {
  for label := range cc.data {
    for rtype := range label.data {
      Msgs := genmsgs(rtype.existing, rtype.desired)
      if no Msgs, continue
      if len(rtype.existing) = 0 {
          yield create(label, rtype, rtype.desiredRecs, Msgs)
      } else if len(rtype.desired) = 0 {
          yield delete(label, rtype, rtype.existingRecs, Msgs)
      } else { // equal
          yield change(label, rtype, rtype.desiredRecs, Msgs)
    }
  }
}

byLabel:
func traverse(cc CompareConfig) {
  for label := range cc.data {
    initialize msgs, desiredRecords
    anyExisting = false
    for rtype := range label.data {
      accumulate Msgs := genmsgs(rtype.existing, rtype.desired)
      if Msgs (i.e. there were changes) {
          accumulate AllDesired := rtype.desiredRecs
          if len(rtype.existing) != 0 {
            anyExisting = true
          }
      }
    }
    if there are Msgs:
        if len(AllDesired) = 0 {
          yield delete(label)
        } else if countAllExisting == 0 {
          yield create(label, AllDesired)
        } else {
          yield change(label, AllDesired)
        }
  }
}

ByRecord:
func traverse(cc CompareConfig) {
  for label := range cc.data {
    for rtype := range label.data {
      create, change, delete := difftargets(rtype.existing, rtype.desired)
          yield creates, changes, deletes
    }
  }
}

Byzone:
func traverse(cc CompareConfig) {
  for label := range cc.data {
    for rtype := range label.data {
      Msgs := genmsgs(rtype.existing, rtype.desired)
      accumulate Msgs
    }
  }
  if len(accumMsgs) == 0 {
    return nil, FirstMsg
  } else {
    return desired, Msgs
  }
}