/*
Copyright 2021 The Dapr Authors
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 postgresql

import (
	"database/sql"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"strconv"
	"time"

	"github.com/agrea/ptr"
	"github.com/pkg/errors"

	"github.com/dapr/components-contrib/state"
	"github.com/dapr/components-contrib/state/query"
	"github.com/dapr/components-contrib/state/utils"
	"github.com/dapr/kit/logger"

	// Blank import for the underlying PostgreSQL driver.
	_ "github.com/jackc/pgx/v5/stdlib"
)

const (
	connectionStringKey        = "connectionString"
	errMissingConnectionString = "missing connection string"
	tableName                  = "state"
	connMaxIdleTimeKey         = "connMaxIdleTime"
)

// postgresDBAccess implements dbaccess.
type postgresDBAccess struct {
	logger           logger.Logger
	metadata         state.Metadata
	db               *sql.DB
	connectionString string
}

// newPostgresDBAccess creates a new instance of postgresAccess.
func newPostgresDBAccess(logger logger.Logger) *postgresDBAccess {
	logger.Debug("Instantiating new PostgreSQL state store")

	return &postgresDBAccess{
		logger: logger,
	}
}

// Init sets up PostgreSQL connection and ensures that the state table exists.
func (p *postgresDBAccess) Init(metadata state.Metadata) error {
	p.logger.Debug("Initializing PostgreSQL state store")
	p.metadata = metadata

	if val, ok := metadata.Properties[connectionStringKey]; ok && val != "" {
		p.connectionString = val
	} else {
		p.logger.Error("Missing postgreSQL connection string")

		return fmt.Errorf(errMissingConnectionString)
	}

	db, err := sql.Open("pgx", p.connectionString)
	if err != nil {
		p.logger.Error(err)

		return err
	}

	p.db = db

	pingErr := db.Ping()
	if pingErr != nil {
		return pingErr
	}

	err = propertyToDuration(p.metadata.Properties, connMaxIdleTimeKey, p.db.SetConnMaxIdleTime)
	if err != nil {
		return err
	}

	err = p.ensureStateTable(tableName)
	if err != nil {
		return err
	}

	return nil
}

// Set makes an insert or update to the database.
func (p *postgresDBAccess) Set(req *state.SetRequest) error {
	return state.SetWithOptions(p.setValue, req)
}

// setValue is an internal implementation of set to enable passing the logic to state.SetWithRetries as a func.
func (p *postgresDBAccess) setValue(req *state.SetRequest) error {
	p.logger.Debug("Setting state value in PostgreSQL")

	err := state.CheckRequestOptions(req.Options)
	if err != nil {
		return err
	}

	if req.Key == "" {
		return fmt.Errorf("missing key in set operation")
	}

	if v, ok := req.Value.(string); ok && v == "" {
		return fmt.Errorf("empty string is not allowed in set operation")
	}

	v := req.Value
	byteArray, isBinary := req.Value.([]uint8)
	if isBinary {
		v = base64.StdEncoding.EncodeToString(byteArray)
	}

	// Convert to json string
	bt, _ := utils.Marshal(v, json.Marshal)
	value := string(bt)

	var result sql.Result

	// Sprintf is required for table name because sql.DB does not substitute parameters for table names.
	// Other parameters use sql.DB parameter substitution.
	if req.ETag == nil {
		result, err = p.db.Exec(fmt.Sprintf(
			`INSERT INTO %s (key, value, isbinary) VALUES ($1, $2, $3)
			ON CONFLICT (key) DO UPDATE SET value = $2, isbinary = $3, updatedate = NOW();`,
			tableName), req.Key, value, isBinary)
	} else {
		// Convert req.ETag to uint32 for postgres XID compatibility
		var etag64 uint64
		etag64, err = strconv.ParseUint(*req.ETag, 10, 32)
		if err != nil {
			return state.NewETagError(state.ETagInvalid, err)
		}
		etag := uint32(etag64)

		// When an etag is provided do an update - no insert
		result, err = p.db.Exec(fmt.Sprintf(
			`UPDATE %s SET value = $1, isbinary = $2, updatedate = NOW()
			 WHERE key = $3 AND xmin = $4;`,
			tableName), value, isBinary, req.Key, etag)
	}

	if err != nil {
		if req.ETag != nil && *req.ETag != "" {
			return state.NewETagError(state.ETagMismatch, err)
		}

		return err
	}

	rows, err := result.RowsAffected()
	if err != nil {
		return err
	}

	if rows != 1 {
		return fmt.Errorf("no item was updated")
	}

	return nil
}

func (p *postgresDBAccess) BulkSet(req []state.SetRequest) error {
	p.logger.Debug("Executing BulkSet request")
	tx, err := p.db.Begin()
	if err != nil {
		return err
	}

	if len(req) > 0 {
		for _, s := range req {
			sa := s // Fix for gosec  G601: Implicit memory aliasing in for loop.
			err = p.Set(&sa)
			if err != nil {
				tx.Rollback()

				return err
			}
		}
	}

	err = tx.Commit()

	return err
}

// Get returns data from the database. If data does not exist for the key an empty state.GetResponse will be returned.
func (p *postgresDBAccess) Get(req *state.GetRequest) (*state.GetResponse, error) {
	p.logger.Debug("Getting state value from PostgreSQL")
	if req.Key == "" {
		return nil, fmt.Errorf("missing key in get operation")
	}

	var value string
	var isBinary bool
	var etag int
	err := p.db.QueryRow(fmt.Sprintf("SELECT value, isbinary, xmin as etag FROM %s WHERE key = $1", tableName), req.Key).Scan(&value, &isBinary, &etag)
	if err != nil {
		// If no rows exist, return an empty response, otherwise return the error.
		if err == sql.ErrNoRows {
			return &state.GetResponse{}, nil
		}

		return nil, err
	}

	if isBinary {
		var s string
		var data []byte

		if err = json.Unmarshal([]byte(value), &s); err != nil {
			return nil, err
		}

		if data, err = base64.StdEncoding.DecodeString(s); err != nil {
			return nil, err
		}

		return &state.GetResponse{
			Data:     data,
			ETag:     ptr.String(strconv.Itoa(etag)),
			Metadata: req.Metadata,
		}, nil
	}

	return &state.GetResponse{
		Data:     []byte(value),
		ETag:     ptr.String(strconv.Itoa(etag)),
		Metadata: req.Metadata,
	}, nil
}

// Delete removes an item from the state store.
func (p *postgresDBAccess) Delete(req *state.DeleteRequest) error {
	return state.DeleteWithOptions(p.deleteValue, req)
}

// deleteValue is an internal implementation of delete to enable passing the logic to state.DeleteWithRetries as a func.
func (p *postgresDBAccess) deleteValue(req *state.DeleteRequest) error {
	p.logger.Debug("Deleting state value from PostgreSQL")
	if req.Key == "" {
		return fmt.Errorf("missing key in delete operation")
	}

	var result sql.Result
	var err error

	if req.ETag == nil {
		result, err = p.db.Exec("DELETE FROM state WHERE key = $1", req.Key)
	} else {
		// Convert req.ETag to uint32 for postgres XID compatibility
		var etag64 uint64
		etag64, err = strconv.ParseUint(*req.ETag, 10, 32)
		if err != nil {
			return state.NewETagError(state.ETagInvalid, err)
		}
		etag := uint32(etag64)

		result, err = p.db.Exec("DELETE FROM state WHERE key = $1 and xmin = $2", req.Key, etag)
	}

	if err != nil {
		return err
	}

	rows, err := result.RowsAffected()
	if err != nil {
		return err
	}

	if rows != 1 && req.ETag != nil && *req.ETag != "" {
		return state.NewETagError(state.ETagMismatch, nil)
	}

	return nil
}

func (p *postgresDBAccess) BulkDelete(req []state.DeleteRequest) error {
	p.logger.Debug("Executing BulkDelete request")
	tx, err := p.db.Begin()
	if err != nil {
		return err
	}

	if len(req) > 0 {
		for _, d := range req {
			da := d // Fix for gosec  G601: Implicit memory aliasing in for loop.
			err = p.Delete(&da)
			if err != nil {
				tx.Rollback()

				return err
			}
		}
	}

	err = tx.Commit()

	return err
}

func (p *postgresDBAccess) ExecuteMulti(request *state.TransactionalStateRequest) error {
	p.logger.Debug("Executing PostgreSQL transaction")

	tx, err := p.db.Begin()
	if err != nil {
		return err
	}

	for _, o := range request.Operations {
		switch o.Operation {
		case state.Upsert:
			var setReq state.SetRequest

			setReq, err = getSet(o)
			if err != nil {
				tx.Rollback()
				return err
			}

			err = p.Set(&setReq)
			if err != nil {
				tx.Rollback()
				return err
			}

		case state.Delete:
			var delReq state.DeleteRequest

			delReq, err = getDelete(o)
			if err != nil {
				tx.Rollback()
				return err
			}

			err = p.Delete(&delReq)
			if err != nil {
				tx.Rollback()
				return err
			}

		default:
			tx.Rollback()
			return fmt.Errorf("unsupported operation: %s", o.Operation)
		}
	}

	err = tx.Commit()

	return err
}

// Query executes a query against store.
func (p *postgresDBAccess) Query(req *state.QueryRequest) (*state.QueryResponse, error) {
	p.logger.Debug("Getting query value from PostgreSQL")
	q := &Query{
		query:  "",
		params: []interface{}{},
	}
	qbuilder := query.NewQueryBuilder(q)
	if err := qbuilder.BuildQuery(&req.Query); err != nil {
		return &state.QueryResponse{}, err
	}
	data, token, err := q.execute(p.logger, p.db)
	if err != nil {
		return &state.QueryResponse{}, err
	}

	return &state.QueryResponse{
		Results: data,
		Token:   token,
	}, nil
}

// Close implements io.Close.
func (p *postgresDBAccess) Close() error {
	if p.db != nil {
		return p.db.Close()
	}

	return nil
}

func (p *postgresDBAccess) ensureStateTable(stateTableName string) error {
	exists, err := tableExists(p.db, stateTableName)
	if err != nil {
		return err
	}

	if !exists {
		p.logger.Info("Creating PostgreSQL state table")
		createTable := fmt.Sprintf(`CREATE TABLE %s (
									key text NOT NULL PRIMARY KEY,
									value jsonb NOT NULL,
									isbinary boolean NOT NULL,
									insertdate TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW(),
									updatedate TIMESTAMP WITH TIME ZONE NULL);`, stateTableName)
		_, err = p.db.Exec(createTable)
		if err != nil {
			return err
		}
	}

	return nil
}

func tableExists(db *sql.DB, tableName string) (bool, error) {
	exists := false
	err := db.QueryRow("SELECT EXISTS (SELECT FROM pg_tables where tablename = $1)", tableName).Scan(&exists)

	return exists, err
}

// Returns the set requests.
func getSet(req state.TransactionalStateOperation) (state.SetRequest, error) {
	setReq, ok := req.Request.(state.SetRequest)
	if !ok {
		return setReq, fmt.Errorf("expecting set request")
	}

	if setReq.Key == "" {
		return setReq, fmt.Errorf("missing key in upsert operation")
	}

	return setReq, nil
}

// Returns the delete requests.
func getDelete(req state.TransactionalStateOperation) (state.DeleteRequest, error) {
	delReq, ok := req.Request.(state.DeleteRequest)
	if !ok {
		return delReq, fmt.Errorf("expecting delete request")
	}

	if delReq.Key == "" {
		return delReq, fmt.Errorf("missing key in upsert operation")
	}

	return delReq, nil
}

func propertyToDuration(props map[string]string, key string, setter func(time.Duration)) error {
	if v, ok := props[key]; ok {
		if d, err := time.ParseDuration(v); err == nil {
			setter(d)
		} else {
			return errors.Wrapf(err, "error converitng %s:%s to time duration", key, v)
		}
	}

	return nil
}