package state

import (
	"context"
	"errors"
	"fmt"
	"time"

	"code.icb4dc0.de/buildr/buildr/modules/state/ent"
	"code.icb4dc0.de/buildr/buildr/modules/state/ent/kventry"

	_ "modernc.org/sqlite"
)

var ErrEmptyKey = errors.New("key may not be empty")

func NewEntStore(ctx context.Context, client *ent.Client) (*EntStateRepository, error) {
	_, err := client.KVEntry.
		Delete().
		Where(kventry.TTLLTE(time.Now().UTC())).
		Exec(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to delete expired entries: %w", err)
	}

	return &EntStateRepository{
		client: client,
	}, nil
}

var _ Store = (*EntStateRepository)(nil)

type EntStateRepository struct {
	client *ent.Client
}

func (s *EntStateRepository) Get(ctx context.Context, key Key) (state []byte, meta Metadata, err error) {
	keyHash := key.Bytes()
	if len(keyHash) == 0 {
		return nil, Metadata{}, ErrEmptyKey
	}
	kvEntry, err := s.client.KVEntry.
		Query().
		Where(kventry.Key(keyHash)).
		Only(ctx)
	if err != nil {
		if ent.IsNotFound(err) {
			return nil, Metadata{}, nil
		}

		return nil, Metadata{}, err
	}

	if kvEntry.TTL != nil && kvEntry.TTL.Before(time.Now().UTC()) {
		return nil, Metadata{}, nil
	}

	return kvEntry.State, metadataForEntry(*kvEntry), nil
}

func (s *EntStateRepository) Set(ctx context.Context, key Key, state []byte, opts ...EntryOption) error {
	keyHash := key.Bytes()
	if len(keyHash) == 0 {
		return ErrEmptyKey
	}

	create := s.client.KVEntry.
		Create()

	for i := range opts {
		opts[i].applyToEntry(create)
	}

	return create.
		SetKey(keyHash).
		SetState(state).
		OnConflict().
		UpdateModifiedAt().
		UpdateState().
		Exec(ctx)
}

func metadataForEntry(entry ent.KVEntry) Metadata {
	return Metadata{
		ModifiedAt: entry.ModifiedAt,
		TTL:        entry.TTL,
	}
}