package dataset

import (
	"context"
	"errors"
	"fmt"
	"net"
	"net/netip"
	"path/filepath"
	"slices"
	"strings"
	"time"

	"git.maze.io/maze/styx/logger"
	"github.com/mjl-/bstore"
)

type bstoreStorage struct {
	db   *bstore.DB
	path string
}

func OpenBStore(name string) (Storage, error) {
	log := logger.StandardLog.Value("database", name)

	if !filepath.IsAbs(name) {
		var err error
		if name, err = filepath.Abs(name); err != nil {
			log.Err(err).Error("Opening BoltDB storage failed; invalid path")
			return nil, err
		}
		log = log.Value("database", name)
	}

	log.Debug("Opening BoltDB storage")
	ctx := context.Background()
	db, err := bstore.Open(ctx, name, nil,
		Group{},
		Client{},
		ClientGroup{},
		List{},
		ListGroup{},
	)
	if err != nil {
		log.Err(err).Error("Opening BoltDB storage failed")
		return nil, err
	}

	var (
		s              = &bstoreStorage{db: db, path: name}
		defaultGroup   Group
		defaultClient4 Client
		defaultClient6 Client
	)

	if defaultGroup, err = s.GroupByName("Default"); errors.Is(err, bstore.ErrAbsent) {
		log.Debug("Creating default group")
		defaultGroup = Group{
			Name:        "Default",
			IsEnabled:   true,
			Description: "Default group",
		}
		if err = s.SaveGroup(&defaultGroup); err != nil {
			return nil, err
		}
	} else if err != nil {
		return nil, err
	}
	if defaultClient4, err = bstore.QueryDB[Client](ctx, db).
		FilterEqual("Network", "ipv4").
		FilterFn(func(client Client) bool {
			return net.ParseIP(client.IP).Equal(net.ParseIP("0.0.0.0")) && client.Mask == 0
		}).Get(); errors.Is(err, bstore.ErrAbsent) {
		log.Debug("Creating default IPv4 clients")
		defaultClient4 = Client{
			Network:     "ipv4",
			IP:          "0.0.0.0",
			Mask:        0,
			Description: "All IPv4 clients",
		}
		if err = s.SaveClient(&defaultClient4); err != nil {
			return nil, err
		}
		if err = s.db.Insert(ctx, &ClientGroup{ClientID: defaultClient4.ID, GroupID: defaultGroup.ID}); err != nil {
			return nil, err
		}
	} else if err != nil {
		return nil, err
	}
	if defaultClient6, err = bstore.QueryDB[Client](ctx, db).
		FilterEqual("Network", "ipv6").
		FilterFn(func(client Client) bool {
			return net.ParseIP(client.IP).Equal(net.ParseIP("::")) && client.Mask == 0
		}).Get(); errors.Is(err, bstore.ErrAbsent) {
		log.Debug("Creating default IPv6 clients")
		defaultClient6 = Client{
			Network:     "ipv6",
			IP:          "::",
			Mask:        0,
			Description: "All IPv6 clients",
		}
		if err = s.SaveClient(&defaultClient6); err != nil {
			return nil, err
		}
		if err = s.db.Insert(ctx, &ClientGroup{ClientID: defaultClient6.ID, GroupID: defaultGroup.ID}); err != nil {
			return nil, err
		}
	} else if err != nil {
		return nil, err
	}

	// Start updater
	log.Trace("Starting list updater")
	NewUpdater(s)

	return s, nil
}

func (s *bstoreStorage) log() logger.Structured {
	return logger.StandardLog.Values(logger.Values{
		"storage":      "bstore",
		"storage_path": s.path,
	})
}

func (s *bstoreStorage) Groups() ([]Group, error) {
	var (
		ctx    = context.Background()
		query  = bstore.QueryDB[Group](ctx, s.db)
		groups = make([]Group, 0)
	)
	for group := range query.All() {
		groups = append(groups, group)
	}
	if err := query.Err(); err != nil && !errors.Is(err, bstore.ErrFinished) {
		return nil, err
	}
	return groups, nil
}

func (s *bstoreStorage) GroupByID(id int64) (Group, error) {
	ctx := context.Background()
	return bstore.QueryDB[Group](ctx, s.db).FilterID(id).Get()
}

func (s *bstoreStorage) GroupByName(name string) (Group, error) {
	ctx := context.Background()
	return bstore.QueryDB[Group](ctx, s.db).FilterFn(func(group Group) bool {
		return strings.EqualFold(group.Name, name)
	}).Get()
}

func (s *bstoreStorage) SaveGroup(group *Group) (err error) {
	ctx := context.Background()
	group.UpdatedAt = time.Now().UTC()
	if group.CreatedAt.Equal(time.Time{}) {
		group.CreatedAt = group.UpdatedAt
		err = s.db.Insert(ctx, group)
	} else {
		err = s.db.Update(ctx, group)
	}
	if err != nil {
		return fmt.Errorf("dataset: save group %s failed: %w", group.Name, err)
	}
	return nil
}

func (s *bstoreStorage) DeleteGroup(group Group) (err error) {
	ctx := context.Background()
	tx, err := s.db.Begin(ctx, true)
	if err != nil {
		return err
	}
	if _, err = bstore.QueryTx[ClientGroup](tx).FilterEqual("GroupID", group.ID).Delete(); err != nil {
		return
	}
	if _, err = bstore.QueryTx[ListGroup](tx).FilterEqual("GroupID", group.ID).Delete(); err != nil {
		return
	}
	if err = tx.Delete(group); err != nil {
		return
	}
	return tx.Commit()
}

func (s *bstoreStorage) Clients() (Clients, error) {
	var (
		ctx     = context.Background()
		query   = bstore.QueryDB[Client](ctx, s.db)
		clients = make(Clients, 0)
	)
	for client := range query.All() {
		clients = append(clients, client)
	}
	if err := query.Err(); err != nil && !errors.Is(err, bstore.ErrFinished) {
		return nil, err
	}
	return clients, nil
}

func (s *bstoreStorage) ClientByID(id int64) (Client, error) {
	ctx := context.Background()
	client, err := bstore.QueryDB[Client](ctx, s.db).FilterID(id).Get()
	if err != nil {
		return client, err
	}
	return s.clientResolveGroups(ctx, client)
}

func (s *bstoreStorage) ClientByIP(ip net.IP) (Client, error) {
	addr, _ := netip.AddrFromSlice(ip)
	return s.ClientByAddr(addr)
}

func (s *bstoreStorage) ClientByAddr(addr netip.Addr) (Client, error) {
	if !addr.IsValid() {
		return Client{}, ErrNotExist{Object: "client"}
	}
	var (
		ctx     = context.Background()
		clients Clients
		network string
	)
	if addr.Is4() {
		network = "ipv4"
	} else {
		network = "ipv6"
	}
	if network == "" {
		return Client{}, ErrNotExist{Object: "client"}
	}
	for client, err := range bstore.QueryDB[Client](ctx, s.db).
		FilterEqual("Network", network).
		FilterFn(func(client Client) bool {
			return client.ContainsAddr(addr)
		}).All() {
		if err != nil {
			return Client{}, err
		}
		clients = append(clients, client)
	}

	var client Client
	switch len(clients) {
	case 0:
		return Client{}, ErrNotExist{Object: "client"}
	case 1:
		client = clients[0]
	default:
		slices.SortStableFunc(clients, func(a, b Client) int {
			return int(b.Mask) - int(a.Mask)
		})
		client = clients[0]
	}
	return s.clientResolveGroups(ctx, client)
}

func (s *bstoreStorage) clientResolveGroups(ctx context.Context, client Client) (Client, error) {
	for clientGroup, err := range bstore.QueryDB[ClientGroup](ctx, s.db).FilterEqual("ClientID", client.ID).All() {
		if err != nil {
			return Client{}, err
		}
		if group, err := s.GroupByID(clientGroup.GroupID); err == nil {
			client.Groups = append(client.Groups, group)
		}
	}
	return client, nil
}

func (s *bstoreStorage) SaveClient(client *Client) (err error) {
	log := s.log()
	ctx := context.Background()
	client.UpdatedAt = time.Now().UTC()

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

	log = log.Values(logger.Values{"ip": client.IP, "mask": client.Mask, "description": client.Description})
	if client.CreatedAt.Equal(time.Time{}) {
		log.Debug("Create client")
		client.CreatedAt = client.UpdatedAt
		if err = tx.Insert(client); err != nil {
			return fmt.Errorf("dataset: client insert failed: %w", err)
		}
	} else {
		log.Debug("Update client")
		if err = tx.Update(client); err != nil {
			return fmt.Errorf("dataset: client update failed: %w", err)
		}
	}

	var deleted int
	if deleted, err = bstore.QueryTx[ClientGroup](tx).FilterEqual("ClientID", client.ID).Delete(); err != nil {
		return fmt.Errorf("dataset: client groups delete failed: %w", err)
	}
	log.Debugf("Deleted %d groups", deleted)
	log.Debugf("Linking %d groups", len(client.Groups))
	for _, group := range client.Groups {
		if err = tx.Insert(&ClientGroup{ClientID: client.ID, GroupID: group.ID}); err != nil {
			return fmt.Errorf("dataset: client groups insert failed: %w", err)
		}
	}

	return tx.Commit()
}

func (s *bstoreStorage) DeleteClient(client Client) (err error) {
	ctx := context.Background()
	tx, err := s.db.Begin(ctx, true)
	if err != nil {
		return err
	}
	if _, err = bstore.QueryTx[ClientGroup](tx).FilterEqual("ClientID", client.ID).Delete(); err != nil {
		return
	}
	if err = tx.Delete(client); err != nil {
		return
	}
	return tx.Commit()
}

func (s *bstoreStorage) Lists() ([]List, error) {
	var (
		ctx   = context.Background()
		query = bstore.QueryDB[List](ctx, s.db)
		lists = make([]List, 0)
	)
	for list := range query.All() {
		lists = append(lists, list)
	}
	if err := query.Err(); err != nil && !errors.Is(err, bstore.ErrFinished) {
		return nil, err
	}
	return lists, nil
}

func (s *bstoreStorage) ListsByGroup(group Group) ([]List, error) {
	ctx := context.Background()
	ids := make([]int64, 0)
	for item, err := range bstore.QueryDB[ListGroup](ctx, s.db).FilterEqual("GroupID", group.ID).All() {
		if err != nil {
			return nil, err
		}
		ids = append(ids, item.ListID)
	}

	var lists []List
	for list, err := range bstore.QueryDB[List](ctx, s.db).FilterIDs(ids).All() {
		if err != nil {
			return nil, err
		}
		lists = append(lists, list)
	}
	return lists, nil
}

func (s *bstoreStorage) ListByID(id int64) (List, error) {
	ctx := context.Background()
	list, err := bstore.QueryDB[List](ctx, s.db).FilterID(id).Get()
	if err != nil {
		return list, err
	}
	return s.listResolveGroups(ctx, list)
}

func (s *bstoreStorage) listResolveGroups(ctx context.Context, list List) (List, error) {
	for listGroup, err := range bstore.QueryDB[ListGroup](ctx, s.db).FilterEqual("ListID", list.ID).All() {
		if err != nil {
			return List{}, err
		}
		if group, err := s.GroupByID(listGroup.GroupID); err == nil {
			list.Groups = append(list.Groups, group)
		}
	}
	return list, nil
}

func (s *bstoreStorage) SaveList(list *List) (err error) {
	if list.Type != ListTypeDomain && list.Type != ListTypeNetwork {
		return fmt.Errorf("storage: unknown list type %q", list.Type)
	}
	if list.Refresh == 0 {
		list.Refresh = DefaultListRefresh
	} else if list.Refresh < MinListRefresh {
		list.Refresh = MinListRefresh
	}
	list.UpdatedAt = time.Now().UTC()

	ctx := context.Background()
	tx, err := s.db.Begin(ctx, true)
	if err != nil {
		return err
	}

	log := s.log()
	log = log.Values(logger.Values{
		"type":       list.Type,
		"source":     list.Source,
		"is_enabled": list.IsEnabled,
		"status":     list.Status,
		"cache":      len(list.Cache),
		"refresh":    list.Refresh,
	})

	if list.CreatedAt.Equal(time.Time{}) {
		log.Debug("Creating list")
		list.CreatedAt = list.UpdatedAt
		if err = tx.Insert(list); err != nil {
			return fmt.Errorf("dataset: list insert failed: %w", err)
		}
	} else {
		log.Debug("Updating list")
		if err = tx.Update(list); err != nil {
			return fmt.Errorf("dataset: list update failed: %w", err)
		}
	}

	var deleted int
	if deleted, err = bstore.QueryTx[ListGroup](tx).FilterEqual("ListID", list.ID).Delete(); err != nil {
		return fmt.Errorf("dataset: list groups delete failed: %w", err)
	}
	log.Debugf("Deleted %d groups", deleted)
	log.Debugf("Linking %d groups", len(list.Groups))
	for _, group := range list.Groups {
		if err = tx.Insert(&ListGroup{ListID: list.ID, GroupID: group.ID}); err != nil {
			return fmt.Errorf("dataset: list groups insert failed: %w", err)
		}
	}

	return tx.Commit()
}

func (s *bstoreStorage) DeleteList(list List) (err error) {
	ctx := context.Background()
	tx, err := s.db.Begin(ctx, true)
	if err != nil {
		return err
	}
	if _, err = bstore.QueryTx[ListGroup](tx).FilterEqual("ListID", list.ID).Delete(); err != nil {
		return
	}
	if err = tx.Delete(list); err != nil {
		return
	}
	return tx.Commit()
}