// 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"
	"encoding/hex"
	"fmt"
	"sort"
	"time"

	"github.com/matrix-org/dendrite/internal/cosmosdbapi"
	"github.com/matrix-org/dendrite/internal/cosmosdbutil"
	"github.com/matrix-org/dendrite/roomserver/storage/tables"
	"github.com/matrix-org/dendrite/roomserver/types"
	"github.com/matrix-org/util"
)

// const stateDataSchema = `
//   CREATE TABLE IF NOT EXISTS roomserver_state_block (
// 	-- The state snapshot NID that identifies this snapshot.
//     state_block_nid INTEGER PRIMARY KEY AUTOINCREMENT,
// 	-- The hash of the state block, which is used to enforce uniqueness. The hash is
// 	-- generated in Dendrite and passed through to the database, as a btree index over
// 	-- this column is cheap and fits within the maximum index size.
// 	state_block_hash BLOB UNIQUE,
// 	-- The event NIDs contained within the state block, encoded as JSON.
//     event_nids TEXT NOT NULL DEFAULT '[]'
//   );
// `

type StateBlockCosmos struct {
	StateBlockNID  int64   `json:"state_block_nid"`
	StateBlockHash []byte  `json:"state_block_hash"`
	EventNIDs      []int64 `json:"event_nids"`
}

type StateBlockCosmosMaxNID struct {
	Max int64 `json:"maxstateblocknid"`
}

type StateBlockCosmosData struct {
	Id         string           `json:"id"`
	Pk         string           `json:"_pk"`
	Tn         string           `json:"_sid"`
	Cn         string           `json:"_cn"`
	ETag       string           `json:"_etag"`
	Timestamp  int64            `json:"_ts"`
	StateBlock StateBlockCosmos `json:"mx_roomserver_state_block"`
}

// Insert a new state block. If we conflict on the hash column then
// we must perform an update so that the RETURNING statement returns the
// ID of the row that we conflicted with, so that we can then refer to
// the original block.
// const insertStateDataSQL = `
// 	INSERT INTO roomserver_state_block (state_block_hash, event_nids)
// 		VALUES ($1, $2)
// 		ON CONFLICT (state_block_hash) DO UPDATE SET event_nids=$2
// 		RETURNING state_block_nid
// `

// "SELECT state_block_nid, event_nids" +
// " FROM roomserver_state_block WHERE state_block_nid IN ($1) ORDER BY state_block_nid ASC"
const bulkSelectStateBlockEntriesSQL = "" +
	"select * from c where c._cn = @x1 " +
	"and ARRAY_CONTAINS(@x2, c.mx_roomserver_state_block.state_block_nid) " +
	"order by c.mx_roomserver_state_block.state_block_nid "

type stateBlockStatements struct {
	db *Database
	// insertStateDataStmt             *sql.Stmt
	bulkSelectStateBlockEntriesStmt string
	tableName                       string
}

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

	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 getStateBlock(s *stateBlockStatements, ctx context.Context, pk string, docId string) (*StateBlockCosmosData, error) {
	response := StateBlockCosmosData{}
	err := cosmosdbapi.GetDocumentOrNil(
		s.db.connection,
		s.db.cosmosConfig,
		ctx,
		pk,
		docId,
		&response)

	if response.Id == "" {
		return nil, cosmosdbutil.ErrNoRows
	}

	return &response, err
}

func setStateBlock(s *stateBlockStatements, ctx context.Context, item StateBlockCosmosData) (*StateBlockCosmosData, error) {
	var optionsReplace = cosmosdbapi.GetReplaceDocumentOptions(item.Pk, item.ETag)
	var _, _, ex = cosmosdbapi.GetClient(s.db.connection).ReplaceDocument(
		ctx,
		s.db.cosmosConfig.DatabaseName,
		s.db.cosmosConfig.ContainerName,
		item.Id,
		&item,
		optionsReplace)
	return &item, ex
}

func NewCosmosDBStateBlockTable(db *Database) (tables.StateBlock, error) {
	s := &stateBlockStatements{
		db: db,
	}

	// s.insertStateDataStmt = insertStateDataSQL
	s.bulkSelectStateBlockEntriesStmt = bulkSelectStateBlockEntriesSQL
	s.tableName = "state_block"
	return s, nil
}

func (s *stateBlockStatements) BulkInsertStateData(
	ctx context.Context,
	txn *sql.Tx,
	entries types.StateEntries,
) (id types.StateBlockNID, err error) {
	// 	INSERT INTO roomserver_state_block (state_block_hash, event_nids)
	// 		VALUES ($1, $2)
	// 		ON CONFLICT (state_block_hash) DO UPDATE SET event_nids=$2
	// 		RETURNING state_block_nid

	entries = entries[:util.SortAndUnique(entries)]
	nids := types.EventNIDs{} // zero slice to not store 'null' in the DB
	ids := []int64{}
	for _, e := range entries {
		nids = append(nids, e.EventNID)
		ids = append(ids, int64(e.EventNID))
	}
	// js, err := json.Marshal(nids)
	// if err != nil {
	// 	return 0, fmt.Errorf("json.Marshal: %w", err)
	// }
	// err = s.insertStateDataStmt.QueryRowContext(
	// 	ctx, nids.Hash(), js,
	// ).Scan(&id)

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

	// 	state_block_hash BLOB UNIQUE,
	docId := hex.EncodeToString(nids.Hash())

	cosmosDocId := cosmosdbapi.GetDocumentId(s.db.cosmosConfig.TenantName, dbCollectionName, docId)
	pk := cosmosdbapi.GetPartitionKey(s.db.cosmosConfig.TenantName, dbCollectionName)

	//See if it exists
	existing, err := getStateBlock(s, ctx, pk, cosmosDocId)
	if err != nil {
		if err != cosmosdbutil.ErrNoRows {
			return 0, err
		}
	}
	if existing != nil {
		//if exists, just update and dont create a new seq
		existing.StateBlock.EventNIDs = ids
		_, err = setStateBlock(s, ctx, *existing)
		if err != nil {
			return 0, err
		}
		return types.StateBlockNID(existing.StateBlock.StateBlockNID), nil
	}

	//Doesnt exist,create a new one
	//     state_block_nid INTEGER PRIMARY KEY AUTOINCREMENT,
	seq, err := GetNextStateBlockNID(s, ctx)
	id = types.StateBlockNID(seq)

	data := StateBlockCosmos{
		StateBlockNID:  seq,
		StateBlockHash: nids.Hash(),
		EventNIDs:      ids,
	}

	var dbData = StateBlockCosmosData{
		Id:         cosmosDocId,
		Tn:         s.db.cosmosConfig.TenantName,
		Cn:         dbCollectionName,
		Pk:         pk,
		Timestamp:  time.Now().Unix(),
		StateBlock: data,
	}

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

	return
}

func (s *stateBlockStatements) BulkSelectStateBlockEntries(
	ctx context.Context, stateBlockNIDs types.StateBlockNIDs,
) ([][]types.EventNID, error) {
	// "SELECT state_block_nid, event_nids" +
	// " FROM roomserver_state_block WHERE state_block_nid IN ($1) ORDER BY state_block_nid ASC"

	intfs := make([]interface{}, len(stateBlockNIDs))
	for i := range stateBlockNIDs {
		intfs[i] = int64(stateBlockNIDs[i])
	}
	// selectOrig := strings.Replace(bulkSelectStateBlockEntriesSQL, "($1)", sqlutil.QueryVariadic(len(intfs)), 1)
	// selectStmt, err := s.db.Prepare(selectOrig)
	// if err != nil {
	// 	return nil, err
	// }
	var dbCollectionName = cosmosdbapi.GetCollectionName(s.db.databaseName, s.tableName)
	params := map[string]interface{}{
		"@x1": dbCollectionName,
		"@x2": stateBlockNIDs,
	}

	// rows, err := selectStmt.QueryContext(ctx, intfs...)
	rows, err := queryStateBlock(s, ctx, s.bulkSelectStateBlockEntriesStmt, params)

	if err != nil {
		return nil, err
	}
	// defer internal.CloseAndLogIfError(ctx, rows, "bulkSelectStateBlockEntries: rows.close() failed")

	results := make([][]types.EventNID, len(stateBlockNIDs))
	i := 0
	// for ; rows.Next(); i++ {
	for _, item := range rows {
		// var stateBlockNID types.StateBlockNID
		// var result json.RawMessage
		// if err = rows.Scan(&stateBlockNID, &result); err != nil {
		// 	return nil, err
		// }
		r := []types.EventNID{}
		// if err = json.Unmarshal(result, &r); err != nil {
		// 	return nil, fmt.Errorf("json.Unmarshal: %w", err)
		// }
		for _, eventNID := range item.StateBlock.EventNIDs {
			r = append(r, types.EventNID(eventNID))
		}
		results[i] = r
		i++
	}
	// if err = rows.Err(); err != nil {
	// 	return nil, err
	// }
	if i != len(stateBlockNIDs) {
		return nil, fmt.Errorf("storage: state data NIDs missing from the database (%d != %d)", len(results), len(stateBlockNIDs))
	}
	return results, err
}

type stateKeyTupleSorter []types.StateKeyTuple

func (s stateKeyTupleSorter) Len() int           { return len(s) }
func (s stateKeyTupleSorter) Less(i, j int) bool { return s[i].LessThan(s[j]) }
func (s stateKeyTupleSorter) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

// Check whether a tuple is in the list. Assumes that the list is sorted.
func (s stateKeyTupleSorter) contains(value types.StateKeyTuple) bool {
	i := sort.Search(len(s), func(i int) bool { return !s[i].LessThan(value) })
	return i < len(s) && s[i] == value
}

// List the unique eventTypeNIDs and eventStateKeyNIDs.
// Assumes that the list is sorted.
func (s stateKeyTupleSorter) typesAndStateKeysAsArrays() (eventTypeNIDs []int64, eventStateKeyNIDs []int64) {
	eventTypeNIDs = make([]int64, len(s))
	eventStateKeyNIDs = make([]int64, len(s))
	for i := range s {
		eventTypeNIDs[i] = int64(s[i].EventTypeNID)
		eventStateKeyNIDs[i] = int64(s[i].EventStateKeyNID)
	}
	eventTypeNIDs = eventTypeNIDs[:util.SortAndUnique(int64Sorter(eventTypeNIDs))]
	eventStateKeyNIDs = eventStateKeyNIDs[:util.SortAndUnique(int64Sorter(eventStateKeyNIDs))]
	return
}

type int64Sorter []int64

func (s int64Sorter) Len() int           { return len(s) }
func (s int64Sorter) Less(i, j int) bool { return s[i] < s[j] }
func (s int64Sorter) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }