# Fabric Private Data PoC - Draft 1

## dependencies

- fabric v2 with implicit private collections
- hlf-proxy:1.7.0, endpoints: blocks, invoke y query

## chaincode

### model

object | storage | key pattern | key e.g. | value type | value e. g.
--- | --- | --- | --- | --- | ---
publicdoc | public | `{countrycode}:{docsubid}` | `AR:1234` | json | `{"version":1, "status":2}`
acl | public | `{doc.key}#acl` | `AR:1234#acl` | []string | `["BR", "PY"]`
event | public | `{doc.key}#event:{countrycode}:{eventsubid}` | `AR:1234#event:BR:0001` | json | `{"id":"AR:1234", "k1":"v1", "k2":"V2"}`
privatedoc | `_implicit_org_{MSPID}` | `{doc.key}#v{version}` | `AR:1234#v2` | json | `{"id":"AR:1234", "k1":"v1", "k2":"V2"}`

### function: AddEvent

param | mandatory | type | e.g.
--- | --- | --- | ---
arg1:docid | x | string | `AR:1234`
arg1:eventsubid | x | string | `1`, `2`
arg2:eventvalue | x | json | `{"eventtype":1,"docstatus":1,"date":"2021-11-01T14:10:23.Z000"}`
arg3:acl | | []string |`["BR", "PY"]`
trasient1:privatedoc | | json | `{"id":"AR:1234", "k1":"v1", "k2":"V2"}`

Rules:

- first event of new doc requires `privatedoc` (creation)
- only creator can to change `privatedoc`
- any event over an existing doc requires its `acl` contains signer

Flow:

publicdoc = shim.GetState(arg-docid)
currentacl = arg-acl       
currentversion = 0

if publicdoc == null: // new doc
   shim.PutState(docid, {version: currentversion, status: arg-eventvalue.status})

else: // doc already exists
   if arg-acl == null: currentacl = shim.GetState(arg3-acl)

   aclCheck with currentacl
   
   if (arg-eventvalue.status != null and arg-eventvalue.status != publicdoc.docstatus) 
   or trasient-privatedoc != null:
      if arg-eventvalue.status != null and arg-eventvalue.status != publicdoc.docstatus: 
         publicdoc.status = arg-eventvalue.docstatus

      if transient-privatedoc != null:
         currentversion = publicdoc.version + 1
      else:
         currentversion = publicdoc.version
         
      shim.PutState(arg1:docid, {version: currentversion, status: arg-eventvalue.status})

shim.PutState(event)

if arg-acl != null: shim.PutState(arg-acl)

if transient-privatedoc != null
   for owner and each org in currentacl
       shim.PutPrivateData(_implicit_org_{MSPID}, {arg-docid}#v{currentversion}, transient-privatedoc)

## using hlf-proxy

### model

- to copy all ledger into dababase table (_"block-consumer style"_)

CREATE TABLE XXXX_STATE (
APPLICATION VARCHAR2, // e. g. SINTIA
BLOCK INTEGER,
TX_ID VARCHAR2(100),
TX_TIMESTAMP DATE,
KEY VARCHAR2(100), 
VALUE VARCHAR2(4000)
);

- to copy private doc

CREATE TABLE XXX_PRIVATE_DOC 
TX_ID VARCHAR2(100),
DOC_ID VARCHAR(100),
DOC_VERSION INTEGER(3),
DOC_CONTENT CLOB
)

### Flow

newblock = GET hlf-proxy endpoint `blocks/{channel}/{blockNumber}?validTxsOnly`

for each tx in newblock:
    if tx.chaincode == XXX and tx.function == 'AddEvent' and writeSet.size > 0:
       // Copy all ledger
       for item on tx.writeSet: db.saveWriteSet( newblock.block, tx.txid, ..., item.key, item.value )

       // trying to recover private data
       docid = getDocidFromKey(tx.writeSet.item[0].key)
    
       publicdoc = filterPublicdocFromWriteSet(tx.writeSet)

       savedVersion = db.selectPrivatedocVersion(docid)
       
       if publicdoc != null 
       and (savedVersion == null or savedVersion != publicdoc.version)
          pk = docid+'#v'+publicdoc.version
             
          privatedoc = POST hlf-proxy "query/{channel}/XXX" body {function:"GetPrivatedoc", args:[pk]}

          if OK // httpStatusCode 200
             db.savePrivatedoc( tx.txid, docid, publicdoc.version, privatedoc )