{-|
Module      : Gargantext.Database.Node.Document.Import
Description : Importing context of texts (documents)
Copyright   : (c) CNRS, 2017-Present
License     : AGPL + CECILL v3
Maintainer  : team@gargantext.org
Stability   : experimental
Portability : POSIX

* Purpose of this module

Enabling "common goods" of text data and respecting privacy.

Gargantext shares as "common good" the links between context of texts
and terms / words / ngrams.

Basically a context of text can be defined as a document (see 'Gargantext.Text').

Issue to tackle in that module: each global document of Gargantext has
to be unique, then shared, but how to respect privacy if needed ?


* Methodology to get uniqueness and privacy by design

As a consequence, when importing a new document in Gargantext, a policy
for the uniqueness of the inserted docuemnts has to be defined. 

That is the purpose of this module which defines its main concepts.

Unique identifier in database is of a 3-tuple of 3 policies that
together define uniqueness:

- Design policy: type of node is needed as TypenameId, that is a
Document or Individual or something else;

- Privacy policy: with ParentId, parent becomes unique, then it enables
users to get their own copy without sharing it with all the users of the
database (in others words parent_id is necessary to preserve privacy for
instance).

- Hash policy: this UniqId is a sha256 uniq id which is the result of
the concatenation of the parameters defined by @hashParameters@.

> -- * Example
> insertTest :: FromRow r => CorpusId -> [Node HyperdataDocument] -> IO [r]
> insertTest :: IO [ReturnId]
> insertTest = connectGargandb "gargantext.ini"
>          >>= \conn -> insertDocuments conn 1 452162 hyperdataDocuments

-}
------------------------------------------------------------------------
{-# LANGUAGE DeriveGeneric        #-}
{-# LANGUAGE NoImplicitPrelude    #-}
{-# LANGUAGE QuasiQuotes          #-}
{-# LANGUAGE DeriveDataTypeable   #-}
{-# LANGUAGE FlexibleInstances    #-}
{-# LANGUAGE TypeSynonymInstances #-}
------------------------------------------------------------------------
module Gargantext.Database.Node.Document.Import where

import Control.Lens (set)

import Data.Aeson (toJSON, Value)
import Data.ByteString.Internal (ByteString)
import Data.Maybe (maybe)
import Data.Typeable (Typeable)
import Database.PostgreSQL.Simple (Connection, FromRow, Query, formatQuery, query, Only(..))
import Database.PostgreSQL.Simple.FromRow (fromRow, field)
import Database.PostgreSQL.Simple.SqlQQ
import Database.PostgreSQL.Simple.ToField (toField)
import Database.PostgreSQL.Simple.ToRow (ToRow(..))
import Database.PostgreSQL.Simple.Types (Values(..), QualifiedIdentifier(..))

import Data.Text (Text)
import qualified Data.Text                   as DT (pack, unpack, concat)
import qualified Data.Digest.Pure.SHA        as SHA (sha256, showDigest)
import qualified Data.ByteString.Lazy.Char8  as DC (pack)

import Gargantext.Database.Config (nodeTypeId)
import Gargantext.Database.Types.Node
-- TODO : the import of Document constructor below does not work
-- import Gargantext.Database.Types.Node (Document)
--import Gargantext.Database.Types.Node (docExample, hyperdataDocument, HyperdataDocument(..)
--                                  , hyperdataDocument_uniqId
--                                  , hyperdataDocument_title
--                                  , hyperdataDocument_abstract
--                                  , hyperdataDocument_source
--                                  , Node(..), node_typename
--                                            , node_userId
--                                            , node_parentId, node_name, node_hyperdata, hyperdataDocuments
--                                  , NodeTypeId
--                                  )
import Gargantext.Prelude

import GHC.Generics (Generic)
---------------------------------------------------------------------------
-- * Main Insert functions

-- ** Database configuration
-- Administrator of the database has to create a uniq index as following SQL command:
-- `create unique index on nodes (typename, parent_id, (hyperdata ->> 'uniqId'));`

-- | Insert Document main function
-- UserId : user who is inserting the documents
-- ParentId : folder ID which is parent of the inserted documents
insertDocuments :: Connection -> UserId -> ParentId -> [HyperdataDocument] -> IO [ReturnId]
insertDocuments conn uId pId hs = query conn queryInsert (Only $ Values fields inputData)
  where
    fields    = map (\t-> QualifiedIdentifier Nothing t) inputSqlTypes
    inputData = prepare uId pId hs

-- | Debug SQL function
--
-- to print rendered query (Debug purpose) use @formatQuery@ function.
insertDocuments_Debug :: Connection -> UserId -> ParentId -> [HyperdataDocument] -> IO ByteString
insertDocuments_Debug conn uId pId hs = formatQuery conn queryInsert (Only $ Values fields inputData)
  where
    fields    = map (\t-> QualifiedIdentifier Nothing t) inputSqlTypes
    inputData = prepare uId pId hs


-- | Input Tables: types of the tables
inputSqlTypes :: [Text]
inputSqlTypes = map DT.pack ["int4","int4","int4","text","jsonb"]

-- | SQL query to insert documents inside the database
queryInsert :: Query
queryInsert = [sql|
    WITH input_rows(typename,user_id,parent_id,name,hyperdata) AS (?)
    , ins AS (
       INSERT INTO nodes (typename,user_id,parent_id,name,hyperdata)
       SELECT * FROM input_rows
       ON CONFLICT (typename, parent_id, (hyperdata ->> 'uniqId')) DO NOTHING -- on unique index
       RETURNING id,hyperdata
       )

    SELECT true AS source                     -- true for 'newly inserted'
         , id
         , hyperdata ->> 'uniqId'  as doi
    FROM   ins
    UNION  ALL
    SELECT false AS source                    -- false for 'not inserted'
         , c.id
         , hyperdata ->> 'uniqId' as doi
    FROM   input_rows
    JOIN   nodes c USING (hyperdata);         -- columns of unique index
           |]

prepare :: UserId -> ParentId -> [HyperdataDocument] -> [InputData]
prepare uId pId = map (\h -> InputData tId uId pId (DT.pack "Doc") (toJSON $ addUniqId h))
  where
    tId = nodeTypeId NodeDocument

------------------------------------------------------------------------
-- * Main Types used

-- ** Return Types

-- | When documents are inserted
-- ReturnType after insertion
data ReturnId = ReturnId { reInserted :: Bool -- ^ if the document is inserted (True: is new, False: is not new)
                         , reId       :: Int  -- ^ always return the id of the document (even new or not new)
                                         --   this is the uniq id in the database
                         , reUniqId   :: Maybe Text -- ^ Hash Id with concatenation of hash parameters
                         } deriving (Show, Generic)

instance FromRow ReturnId where
  fromRow = ReturnId <$> field <*> field <*> field

-- ** Insert Types

type UserId   = Int
type ParentId = Int

data InputData = InputData { inTypenameId :: NodeTypeId
                           , inUserId     :: UserId
                           , inParentId   :: ParentId
                           , inName       :: Text
                           , inHyper      :: Value
                           } deriving (Show, Generic, Typeable)

instance ToRow InputData where
  toRow inputData = [ toField (inTypenameId inputData)
                    , toField (inUserId     inputData)
                    , toField (inParentId   inputData)
                    , toField (inName       inputData)
                    , toField (inHyper      inputData)
                    ]

---------------------------------------------------------------------------
-- * Uniqueness of document definition

hashParameters :: [(HyperdataDocument -> Text)]
hashParameters = [ \d -> maybe' (_hyperdataDocument_title    d)
                 , \d -> maybe' (_hyperdataDocument_abstract d)
                 , \d -> maybe' (_hyperdataDocument_source   d)
                 , \d -> maybe' (_hyperdataDocument_publication_date   d)
                 ]
                   where
                     maybe' = maybe (DT.pack "") identity

addUniqId :: HyperdataDocument -> HyperdataDocument
addUniqId doc = set hyperdataDocument_uniqId (Just hash) doc
  where
    hash = uniqId $ DT.concat $ map ($ doc) hashParameters

    uniqId :: Text -> Text
    uniqId = DT.pack . SHA.showDigest . SHA.sha256 . DC.pack . DT.unpack

---------------------------------------------------------------------------