package sql

import (
	"context"
	"database/sql"
	"errors"
	"regexp"
	"strconv"
	"strings"

	"github.com/cockroachdb/cockroach-go/v2/crdb"
	"github.com/lib/pq"
	"github.com/zitadel/logging"

	caos_errs "github.com/zitadel/zitadel/internal/errors"
	"github.com/zitadel/zitadel/internal/eventstore/repository"
)

const (
	//as soon as stored procedures are possible in crdb
	// we could move the code to migrations and coll the procedure
	// traking issue: https://github.com/cockroachdb/cockroach/issues/17511
	//
	//previous_data selects the needed data of the latest event of the aggregate
	// and buffers it (crdb inmemory)
	crdbInsert = "WITH previous_data (aggregate_type_sequence, aggregate_sequence, resource_owner) AS (" +
		"SELECT agg_type.seq, agg.seq, agg.ro FROM " +
		"(" +
		//max sequence of requested aggregate type
		" SELECT MAX(event_sequence) seq, 1 join_me" +
		" FROM eventstore.events" +
		" WHERE aggregate_type = $2" +
		" AND (CASE WHEN $9::STRING IS NULL THEN instance_id is null else instance_id = $9::STRING END)" +
		") AS agg_type " +
		// combined with
		"LEFT JOIN " +
		"(" +
		// max sequence and resource owner of aggregate root
		" SELECT event_sequence seq, resource_owner ro, 1 join_me" +
		" FROM eventstore.events" +
		" WHERE aggregate_type = $2 AND aggregate_id = $3" +
		" AND (CASE WHEN $9::STRING IS NULL THEN instance_id is null else instance_id = $9::STRING END)" +
		" ORDER BY event_sequence DESC" +
		" LIMIT 1" +
		") AS agg USING(join_me)" +
		") " +
		"INSERT INTO eventstore.events (" +
		" event_type," +
		" aggregate_type," +
		" aggregate_id," +
		" aggregate_version," +
		" creation_date," +
		" event_data," +
		" editor_user," +
		" editor_service," +
		" resource_owner," +
		" instance_id," +
		" event_sequence," +
		" previous_aggregate_sequence," +
		" previous_aggregate_type_sequence" +
		") " +
		// defines the data to be inserted
		"SELECT" +
		" $1::VARCHAR AS event_type," +
		" $2::VARCHAR AS aggregate_type," +
		" $3::VARCHAR AS aggregate_id," +
		" $4::VARCHAR AS aggregate_version," +
		" NOW() AS creation_date," +
		" $5::JSONB AS event_data," +
		" $6::VARCHAR AS editor_user," +
		" $7::VARCHAR AS editor_service," +
		" IFNULL((resource_owner), $8::VARCHAR) AS resource_owner," +
		" $9::VARCHAR AS instance_id," +
		" NEXTVAL(CONCAT('eventstore.', IF($9 <> '', CONCAT('i_', $9), 'system'), '_seq'))," +
		" aggregate_sequence AS previous_aggregate_sequence," +
		" aggregate_type_sequence AS previous_aggregate_type_sequence " +
		"FROM previous_data " +
		"RETURNING id, event_sequence, previous_aggregate_sequence, previous_aggregate_type_sequence, creation_date, resource_owner, instance_id"

	uniqueInsert = `INSERT INTO eventstore.unique_constraints
					(
						unique_type,
						unique_field,
						instance_id
					) 
					VALUES (  
						$1,
						$2,
						$3
					)`

	uniqueDelete = `DELETE FROM eventstore.unique_constraints
					WHERE unique_type = $1 and unique_field = $2 and instance_id = $3`
)

type CRDB struct {
	client *sql.DB
}

func NewCRDB(client *sql.DB) *CRDB {
	return &CRDB{client}
}

func (db *CRDB) Health(ctx context.Context) error { return db.client.Ping() }

// Push adds all events to the eventstreams of the aggregates.
// This call is transaction save. The transaction will be rolled back if one event fails
func (db *CRDB) Push(ctx context.Context, events []*repository.Event, uniqueConstraints ...*repository.UniqueConstraint) error {
	err := crdb.ExecuteTx(ctx, db.client, nil, func(tx *sql.Tx) error {

		var (
			previousAggregateSequence     Sequence
			previousAggregateTypeSequence Sequence
		)
		for _, event := range events {
			err := tx.QueryRowContext(ctx, crdbInsert,
				event.Type,
				event.AggregateType,
				event.AggregateID,
				event.Version,
				Data(event.Data),
				event.EditorUser,
				event.EditorService,
				event.ResourceOwner,
				event.InstanceID,
			).Scan(&event.ID, &event.Sequence, &previousAggregateSequence, &previousAggregateTypeSequence, &event.CreationDate, &event.ResourceOwner, &event.InstanceID)

			event.PreviousAggregateSequence = uint64(previousAggregateSequence)
			event.PreviousAggregateTypeSequence = uint64(previousAggregateTypeSequence)

			if err != nil {
				logging.WithFields(
					"aggregate", event.AggregateType,
					"aggregateId", event.AggregateID,
					"aggregateType", event.AggregateType,
					"eventType", event.Type,
					"instanceID", event.InstanceID,
				).WithError(err).Info("query failed")
				return caos_errs.ThrowInternal(err, "SQL-SBP37", "unable to create event")
			}
		}

		err := db.handleUniqueConstraints(ctx, tx, uniqueConstraints...)
		if err != nil {
			return err
		}
		return nil
	})
	if err != nil && !errors.Is(err, &caos_errs.CaosError{}) {
		err = caos_errs.ThrowInternal(err, "SQL-DjgtG", "unable to store events")
	}

	return err
}

var instanceRegexp = regexp.MustCompile(`eventstore\.i_[0-9a-zA-Z]{1,}_seq`)

func (db *CRDB) CreateInstance(ctx context.Context, instanceID string) error {
	row := db.client.QueryRowContext(ctx, "SELECT CONCAT('eventstore.i_', $1, '_seq')", instanceID)
	if row.Err() != nil {
		return caos_errs.ThrowInvalidArgument(row.Err(), "SQL-7gtFA", "Errors.InvalidArgument")
	}
	var sequenceName string
	if err := row.Scan(&sequenceName); err != nil || !instanceRegexp.MatchString(sequenceName) {
		return caos_errs.ThrowInvalidArgument(err, "SQL-7gtFA", "Errors.InvalidArgument")
	}

	if _, err := db.client.ExecContext(ctx, "CREATE SEQUENCE "+sequenceName); err != nil {
		return caos_errs.ThrowInternal(err, "SQL-7gtFA", "Errors.Internal")
	}

	return nil
}

// handleUniqueConstraints adds or removes unique constraints
func (db *CRDB) handleUniqueConstraints(ctx context.Context, tx *sql.Tx, uniqueConstraints ...*repository.UniqueConstraint) (err error) {
	if len(uniqueConstraints) == 0 || (len(uniqueConstraints) == 1 && uniqueConstraints[0] == nil) {
		return nil
	}

	for _, uniqueConstraint := range uniqueConstraints {
		uniqueConstraint.UniqueField = strings.ToLower(uniqueConstraint.UniqueField)
		switch uniqueConstraint.Action {
		case repository.UniqueConstraintAdd:
			_, err := tx.ExecContext(ctx, uniqueInsert, uniqueConstraint.UniqueType, uniqueConstraint.UniqueField, uniqueConstraint.InstanceID)
			if err != nil {
				logging.WithFields(
					"unique_type", uniqueConstraint.UniqueType,
					"unique_field", uniqueConstraint.UniqueField).WithError(err).Info("insert unique constraint failed")

				if db.isUniqueViolationError(err) {
					return caos_errs.ThrowAlreadyExists(err, "SQL-M0dsf", uniqueConstraint.ErrorMessage)
				}

				return caos_errs.ThrowInternal(err, "SQL-dM9ds", "unable to create unique constraint ")
			}
		case repository.UniqueConstraintRemoved:
			_, err := tx.ExecContext(ctx, uniqueDelete, uniqueConstraint.UniqueType, uniqueConstraint.UniqueField, uniqueConstraint.InstanceID)
			if err != nil {
				logging.WithFields(
					"unique_type", uniqueConstraint.UniqueType,
					"unique_field", uniqueConstraint.UniqueField).WithError(err).Info("delete unique constraint failed")
				return caos_errs.ThrowInternal(err, "SQL-6n88i", "unable to remove unique constraint ")
			}
		}
	}
	return nil
}

// Filter returns all events matching the given search query
func (db *CRDB) Filter(ctx context.Context, searchQuery *repository.SearchQuery) (events []*repository.Event, err error) {
	events = []*repository.Event{}
	err = query(ctx, db, searchQuery, &events)
	if err != nil {
		return nil, err
	}

	return events, nil
}

//LatestSequence returns the latests sequence found by the the search query
func (db *CRDB) LatestSequence(ctx context.Context, searchQuery *repository.SearchQuery) (uint64, error) {
	var seq Sequence
	err := query(ctx, db, searchQuery, &seq)
	if err != nil {
		return 0, err
	}
	return uint64(seq), nil
}

func (db *CRDB) db() *sql.DB {
	return db.client
}

func (db *CRDB) orderByEventSequence(desc bool) string {
	if desc {
		return " ORDER BY event_sequence DESC"
	}

	return " ORDER BY event_sequence"
}

func (db *CRDB) eventQuery() string {
	return "SELECT" +
		" creation_date" +
		", event_type" +
		", event_sequence" +
		", previous_aggregate_sequence" +
		", previous_aggregate_type_sequence" +
		", event_data" +
		", editor_service" +
		", editor_user" +
		", resource_owner" +
		", instance_id" +
		", aggregate_type" +
		", aggregate_id" +
		", aggregate_version" +
		" FROM eventstore.events"
}

func (db *CRDB) maxSequenceQuery() string {
	return "SELECT MAX(event_sequence) FROM eventstore.events"
}

func (db *CRDB) columnName(col repository.Field) string {
	switch col {
	case repository.FieldAggregateID:
		return "aggregate_id"
	case repository.FieldAggregateType:
		return "aggregate_type"
	case repository.FieldSequence:
		return "event_sequence"
	case repository.FieldResourceOwner:
		return "resource_owner"
	case repository.FieldInstanceID:
		return "instance_id"
	case repository.FieldEditorService:
		return "editor_service"
	case repository.FieldEditorUser:
		return "editor_user"
	case repository.FieldEventType:
		return "event_type"
	case repository.FieldEventData:
		return "event_data"
	default:
		return ""
	}
}

func (db *CRDB) conditionFormat(operation repository.Operation) string {
	switch operation {
	case repository.OperationIn:
		return "%s %s ANY(?)"
	case repository.OperationNotIn:
		return "%s %s ALL(?)"
	}
	return "%s %s ?"
}

func (db *CRDB) operation(operation repository.Operation) string {
	switch operation {
	case repository.OperationEquals, repository.OperationIn:
		return "="
	case repository.OperationGreater:
		return ">"
	case repository.OperationLess:
		return "<"
	case repository.OperationJSONContains:
		return "@>"
	case repository.OperationNotIn:
		return "<>"
	}
	return ""
}

var (
	placeholder = regexp.MustCompile(`\?`)
)

//placeholder replaces all "?" with postgres placeholders ($<NUMBER>)
func (db *CRDB) placeholder(query string) string {
	occurances := placeholder.FindAllStringIndex(query, -1)
	if len(occurances) == 0 {
		return query
	}
	replaced := query[:occurances[0][0]]

	for i, l := range occurances {
		nextIDX := len(query)
		if i < len(occurances)-1 {
			nextIDX = occurances[i+1][0]
		}
		replaced = replaced + "$" + strconv.Itoa(i+1) + query[l[1]:nextIDX]
	}
	return replaced
}

func (db *CRDB) isUniqueViolationError(err error) bool {
	if pqErr, ok := err.(*pq.Error); ok {
		if pqErr.Code == "23505" {
			return true
		}
	}
	return false
}