// Copyright 2017-2018 New Vector Ltd
// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package cosmosdb

import (
	"context"
	"database/sql"
	"fmt"
	"time"

	"github.com/matrix-org/dendrite/internal/cosmosdbapi"

	"github.com/matrix-org/dendrite/roomserver/storage/tables"
	"github.com/matrix-org/dendrite/roomserver/types"
)

// const eventJSONSchema = `
//   CREATE TABLE IF NOT EXISTS roomserver_event_json (
//     event_nid INTEGER NOT NULL PRIMARY KEY,
//     event_json TEXT NOT NULL
//   );
// `

type EventJSONCosmos struct {
	EventNID  int64  `json:"event_nid"`
	EventJSON []byte `json:"event_json"`
}

type EventJSONCosmosData struct {
	Id        string          `json:"id"`
	Pk        string          `json:"_pk"`
	Cn        string          `json:"_cn"`
	ETag      string          `json:"_etag"`
	Timestamp int64           `json:"_ts"`
	EventJSON EventJSONCosmos `json:"mx_roomserver_event_json"`
}

// const insertEventJSONSQL = `
// 	INSERT OR REPLACE INTO roomserver_event_json (event_nid, event_json) VALUES ($1, $2)
// `

// Bulk event JSON lookup by numeric event ID.
// Sort by the numeric event ID.
// This means that we can use binary search to lookup by numeric event ID.
// 	SELECT event_nid, event_json FROM roomserver_event_json
// 	  WHERE event_nid IN ($1)
// 	  ORDER BY event_nid ASC
const bulkSelectEventJSONSQL = "" +
	"select * from c where c._cn = @x1 " +
	"and ARRAY_CONTAINS(@x2, c.mx_roomserver_event_json.event_nid) " +
	"order by c.mx_roomserver_event_json.event_nid asc"

type eventJSONStatements struct {
	db *Database
	// insertEventJSONStmt     *sql.Stmt
	bulkSelectEventJSONStmt string
	tableName               string
}

func queryEventJSON(s *eventJSONStatements, ctx context.Context, qry string, params map[string]interface{}) ([]EventJSONCosmosData, error) {
	var dbCollectionName = cosmosdbapi.GetCollectionName(s.db.databaseName, s.tableName)
	var pk = cosmosdbapi.GetPartitionKey(s.db.cosmosConfig.ContainerName, dbCollectionName)
	var response []EventJSONCosmosData

	var optionsQry = cosmosdbapi.GetQueryDocumentsOptions(pk)
	var query = cosmosdbapi.GetQuery(qry, params)
	_, err := cosmosdbapi.GetClient(s.db.connection).QueryDocuments(
		ctx,
		s.db.cosmosConfig.DatabaseName,
		s.db.cosmosConfig.ContainerName,
		query,
		&response,
		optionsQry)

	if err != nil {
		return nil, err
	}
	return response, nil
}

func NewCosmosDBEventJSONTable(db *Database) (tables.EventJSON, error) {
	s := &eventJSONStatements{
		db: db,
	}
	// _, err := db.Exec(eventJSONSchema)
	// if err != nil {
	// 	return nil, err
	// }
	// return s, shared.StatementList{
	// 	{&s.insertEventJSONStmt, insertEventJSONSQL},
	s.bulkSelectEventJSONStmt = bulkSelectEventJSONSQL
	// }.Prepare(db)
	s.tableName = "event_json"
	return s, nil
}

func (s *eventJSONStatements) InsertEventJSON(
	ctx context.Context, txn *sql.Tx, eventNID types.EventNID, eventJSON []byte,
) error {

	// _, err := sqlutil.TxStmt(txn, s.insertEventJSONStmt).ExecContext(ctx, int64(eventNID), eventJSON)
	// INSERT OR REPLACE INTO roomserver_event_json (event_nid, event_json) VALUES ($1, $2)

	var dbCollectionName = cosmosdbapi.GetCollectionName(s.db.databaseName, s.tableName)

	docId := fmt.Sprintf("%d", eventNID)
	cosmosDocId := cosmosdbapi.GetDocumentId(s.db.cosmosConfig.ContainerName, dbCollectionName, docId)
	pk := cosmosdbapi.GetPartitionKey(s.db.cosmosConfig.ContainerName, dbCollectionName)

	data := EventJSONCosmos{
		EventNID:  int64(eventNID),
		EventJSON: eventJSON,
	}

	var dbData = EventJSONCosmosData{
		Id:        cosmosDocId,
		Cn:        dbCollectionName,
		Pk:        pk,
		Timestamp: time.Now().Unix(),
		EventJSON: data,
	}

	//Insert OR Replace
	var options = cosmosdbapi.GetUpsertDocumentOptions(dbData.Pk)
	var _, _, err = cosmosdbapi.GetClient(s.db.connection).CreateDocument(
		ctx,
		s.db.cosmosConfig.DatabaseName,
		s.db.cosmosConfig.ContainerName,
		&dbData,
		options)

	return err
}

func (s *eventJSONStatements) BulkSelectEventJSON(
	ctx context.Context, eventNIDs []types.EventNID,
) ([]tables.EventJSONPair, error) {

	// SELECT event_nid, event_json FROM roomserver_event_json
	//   WHERE event_nid IN ($1)
	//   ORDER BY event_nid ASC

	var dbCollectionName = cosmosdbapi.GetCollectionName(s.db.databaseName, s.tableName)
	params := map[string]interface{}{
		"@x1": dbCollectionName,
		"@x2": eventNIDs,
	}

	response, err := queryEventJSON(s, ctx, s.bulkSelectEventJSONStmt, params)

	if err != nil {
		return nil, err
	}

	// We know that we will only get as many results as event NIDs
	// because of the unique constraint on event NIDs.
	// So we can allocate an array of the correct size now.
	// We might get fewer results than NIDs so we adjust the length of the slice before returning it.
	results := make([]tables.EventJSONPair, len(eventNIDs))
	i := 0
	for _, item := range response {
		result := &results[i]
		result.EventNID = types.EventNID(item.EventJSON.EventNID)
		result.EventJSON = item.EventJSON.EventJSON
		i++
	}
	return results[:i], nil
}