package postgresadmin

import (
	"context"
	"encoding/json"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgtype"

	"proxy-pool/internal/domain/adminstate"
)

func (adapter *adapter) Claim(
	ctx context.Context,
	command adminstate.ClaimCommand,
) ([]adminstate.Event, error) {
	if err := contextError(ctx); err != nil {
		return nil, err
	}
	if command.Validate() != nil || !adapter.valid() {
		return nil, adminstate.ErrInvalidCommand
	}
	tx, err := adapter.begin(ctx, pgx.TxOptions{AccessMode: pgx.ReadWrite}, "begin outbox claim")
	if err != nil {
		return nil, err
	}
	defer rollback(tx)

	now := utc(command.Now)
	claimUntil := now.Add(command.Lease)
	rows, err := tx.Query(ctx, `
		WITH candidates AS (
			SELECT id
			FROM admin_outbox
			WHERE published_at IS NULL
				AND (claim_until IS NULL OR claim_until <= $1)
			ORDER BY id
			FOR UPDATE SKIP LOCKED
			LIMIT $2
		), claimed AS (
			UPDATE admin_outbox AS outbox
			SET claim_owner = $3, claim_until = $4
			FROM candidates
			WHERE outbox.id = candidates.id
			RETURNING outbox.id, outbox.revision, outbox.event_type,
				outbox.aggregate_type, outbox.aggregate_id, outbox.payload,
				outbox.occurred_at, outbox.claim_owner, outbox.claim_until,
				outbox.published_at
		)
		SELECT id, revision, event_type, aggregate_type, aggregate_id, payload,
			occurred_at, claim_owner, claim_until, published_at
		FROM claimed
		ORDER BY id`, now, command.Limit, command.ConsumerID, claimUntil)
	if err != nil {
		return nil, databaseError(ctx, "claim outbox events", err)
	}
	defer rows.Close()

	events := make([]adminstate.Event, 0, command.Limit)
	for rows.Next() {
		event := adminstate.Event{}
		var id int64
		var revision int64
		var payload []byte
		var claimedBy pgtype.Text
		var claimedUntil pgtype.Timestamptz
		var publishedAt pgtype.Timestamptz
		if err := rows.Scan(
			&id,
			&revision,
			&event.Type,
			&event.AggregateType,
			&event.AggregateID,
			&payload,
			&event.OccurredAt,
			&claimedBy,
			&claimedUntil,
			&publishedAt,
		); err != nil {
			return nil, databaseError(ctx, "decode claimed outbox events", err)
		}
		convertedID, idOK := domainID(id)
		convertedRevision, revisionOK := domainID(revision)
		if !idOK || !revisionOK || !claimedBy.Valid || !claimedUntil.Valid {
			return nil, unavailable("decode claimed outbox events")
		}
		event.ID = convertedID
		event.Revision = convertedRevision
		event.Payload = append(json.RawMessage(nil), payload...)
		event.OccurredAt = utc(event.OccurredAt)
		event.ClaimedBy = claimedBy.String
		value := utc(claimedUntil.Time)
		event.ClaimUntil = &value
		if publishedAt.Valid {
			value := utc(publishedAt.Time)
			event.PublishedAt = &value
		}
		events = append(events, event)
	}
	if err := rows.Err(); err != nil {
		return nil, databaseError(ctx, "claim outbox events", err)
	}
	if err := commit(ctx, tx, "commit outbox claim"); err != nil {
		return nil, err
	}
	return events, nil
}

func (adapter *adapter) Acknowledge(
	ctx context.Context,
	command adminstate.AcknowledgeCommand,
) error {
	if err := contextError(ctx); err != nil {
		return err
	}
	if command.Validate() != nil || !adapter.valid() {
		return adminstate.ErrInvalidCommand
	}
	eventIDs, ok := eventDatabaseIDs(command.EventIDs)
	if !ok {
		return adminstate.ErrNotFound
	}
	tx, err := adapter.begin(ctx, pgx.TxOptions{AccessMode: pgx.ReadWrite}, "begin outbox acknowledge")
	if err != nil {
		return err
	}
	defer rollback(tx)

	rows, err := tx.Query(ctx, `
		SELECT id, published_at, claim_owner, claim_until
		FROM admin_outbox
		WHERE id = ANY($1::bigint[])
		ORDER BY id
		FOR UPDATE`, eventIDs)
	if err != nil {
		return databaseError(ctx, "lock acknowledged outbox events", err)
	}
	count := 0
	now := utc(command.Now)
	conflict := false
	for rows.Next() {
		var id int64
		var publishedAt pgtype.Timestamptz
		var claimOwner pgtype.Text
		var claimUntil pgtype.Timestamptz
		if err := rows.Scan(&id, &publishedAt, &claimOwner, &claimUntil); err != nil {
			rows.Close()
			return databaseError(ctx, "decode acknowledged outbox events", err)
		}
		count++
		if publishedAt.Valid || !claimOwner.Valid || claimOwner.String != command.ConsumerID ||
			!claimUntil.Valid || !now.Before(claimUntil.Time) {
			conflict = true
		}
	}
	if err := rows.Err(); err != nil {
		rows.Close()
		return databaseError(ctx, "lock acknowledged outbox events", err)
	}
	rows.Close()
	if count != len(eventIDs) {
		return adminstate.ErrNotFound
	}
	if conflict {
		return adminstate.ErrConflict
	}

	commandTag, err := tx.Exec(ctx, `
		UPDATE admin_outbox
		SET published_at = $1
		WHERE id = ANY($2::bigint[])`, now, eventIDs)
	if err != nil {
		return databaseError(ctx, "publish outbox events", err)
	}
	if commandTag.RowsAffected() != int64(len(eventIDs)) {
		return unavailable("publish outbox events")
	}
	return commit(ctx, tx, "commit outbox acknowledge")
}