package crdb

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

	"github.com/zitadel/zitadel/internal/database"
	"github.com/zitadel/zitadel/internal/errors"
	"github.com/zitadel/zitadel/internal/eventstore"
)

const (
	currentSequenceStmtFormat            = `SELECT current_sequence, aggregate_type, instance_id FROM %s WHERE projection_name = $1 AND instance_id = ANY ($2) FOR UPDATE`
	currentSequenceStmtWithoutLockFormat = `SELECT current_sequence, aggregate_type, instance_id FROM %s WHERE projection_name = $1 AND instance_id = ANY ($2)`
	updateCurrentSequencesStmtFormat     = `INSERT INTO %s (projection_name, aggregate_type, current_sequence, instance_id, timestamp) VALUES `
	updateCurrentSequencesConflictStmt   = ` ON CONFLICT (projection_name, aggregate_type, instance_id) DO UPDATE SET current_sequence = EXCLUDED.current_sequence, timestamp = EXCLUDED.timestamp`
)

type currentSequences map[eventstore.AggregateType][]*instanceSequence

type instanceSequence struct {
	instanceID string
	sequence   uint64
}

func (h *StatementHandler) currentSequences(ctx context.Context, isTx bool, query func(context.Context, func(*sql.Rows) error, string, ...interface{}) error, instanceIDs database.StringArray) (currentSequences, error) {
	stmt := h.currentSequenceStmt
	if !isTx {
		stmt = h.currentSequenceWithoutLockStmt
	}

	sequences := make(currentSequences, len(h.aggregates))
	err := query(ctx,
		func(rows *sql.Rows) error {
			for rows.Next() {
				var (
					aggregateType eventstore.AggregateType
					sequence      uint64
					instanceID    string
				)

				err := rows.Scan(&sequence, &aggregateType, &instanceID)
				if err != nil {
					return errors.ThrowInternal(err, "CRDB-dbatK", "scan failed")
				}

				sequences[aggregateType] = append(sequences[aggregateType], &instanceSequence{
					sequence:   sequence,
					instanceID: instanceID,
				})
			}
			return nil
		},
		stmt, h.ProjectionName, instanceIDs)
	if err != nil {
		return nil, err
	}
	return sequences, nil
}

func (h *StatementHandler) updateCurrentSequences(tx *sql.Tx, sequences currentSequences) error {
	valueQueries := make([]string, 0, len(sequences))
	valueCounter := 0
	values := make([]interface{}, 0, len(sequences)*3)
	for aggregate, instanceSequence := range sequences {
		for _, sequence := range instanceSequence {
			valueQueries = append(valueQueries, "($"+strconv.Itoa(valueCounter+1)+", $"+strconv.Itoa(valueCounter+2)+", $"+strconv.Itoa(valueCounter+3)+", $"+strconv.Itoa(valueCounter+4)+", NOW())")
			valueCounter += 4
			values = append(values, h.ProjectionName, aggregate, sequence.sequence, sequence.instanceID)
		}
	}

	res, err := tx.Exec(h.updateSequencesBaseStmt+strings.Join(valueQueries, ", ")+updateCurrentSequencesConflictStmt, values...)
	if err != nil {
		return errors.ThrowInternal(err, "CRDB-TrH2Z", "unable to exec update sequence")
	}
	if rows, _ := res.RowsAffected(); rows < 1 {
		return errSeqNotUpdated
	}
	return nil
}