package service

import (
	"fmt"

	"spend-sparrow/db"
	"spend-sparrow/log"
	"spend-sparrow/types"

	"github.com/google/uuid"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
)

var (
	treasureChestMetric = promauto.NewCounterVec(
		prometheus.CounterOpts{
			Name: "spendsparrow_treasurechest_total",
			Help: "The total of treasurechest operations",
		},
		[]string{"operation"},
	)
)

type TreasureChest interface {
	Add(user *types.User, parentId, name string) (*types.TreasureChest, error)
	Update(user *types.User, id, parentId, name string) (*types.TreasureChest, error)
	Get(user *types.User, id string) (*types.TreasureChest, error)
	GetAll(user *types.User) ([]*types.TreasureChest, error)
	Delete(user *types.User, id string) error
}

type TreasureChestImpl struct {
	db       db.TreasureChest
	clock    Clock
	random   Random
	settings *types.Settings
}

func NewTreasureChest(db db.TreasureChest, random Random, clock Clock, settings *types.Settings) TreasureChest {
	return TreasureChestImpl{
		db:       db,
		clock:    clock,
		random:   random,
		settings: settings,
	}
}

func (s TreasureChestImpl) Add(user *types.User, parentId, name string) (*types.TreasureChest, error) {
	treasureChestMetric.WithLabelValues("add").Inc()

	if user == nil {
		return nil, ErrUnauthorized
	}

	newId, err := s.random.UUID()
	if err != nil {
		return nil, types.ErrInternal
	}

	err = validateString(name, "name")
	if err != nil {
		return nil, err
	}

	parentUuid := uuid.Nil
	if parentId != "" {
		parent, err := s.Get(user, parentId)
		if err != nil {
			return nil, err
		}
		if parent.ParentId != uuid.Nil {
			return nil, fmt.Errorf("only a depth of 1 allowed: %w", ErrBadRequest)
		}
		parentUuid = parent.Id
	}

	treasureChest := &types.TreasureChest{
		Id:       newId,
		ParentId: parentUuid,
		UserId:   user.Id,

		Name: name,

		CurrentBalance: 0,

		CreatedAt: s.clock.Now(),
		CreatedBy: user.Id,
		UpdatedAt: nil,
		UpdatedBy: nil,
	}

	err = s.db.Insert(user.Id, treasureChest)
	if err != nil {
		return nil, types.ErrInternal
	}

	savedtreasureChest, err := s.db.Get(user.Id, newId)
	if err != nil {
		log.Error("treasureChest %v not found after insert: %v", newId, err)
		return nil, types.ErrInternal
	}
	return savedtreasureChest, nil
}

func (s TreasureChestImpl) Update(user *types.User, idStr, parentId, name string) (*types.TreasureChest, error) {
	treasureChestMetric.WithLabelValues("update").Inc()
	if user == nil {
		return nil, ErrUnauthorized
	}
	err := validateString(name, "name")
	if err != nil {
		return nil, err
	}
	id, err := uuid.Parse(idStr)
	if err != nil {
		log.Error("treasureChest update: %v", err)
		return nil, fmt.Errorf("could not parse Id: %w", ErrBadRequest)
	}

	treasureChest, err := s.db.Get(user.Id, id)
	if err != nil {
		if err == db.ErrNotFound {
			return nil, fmt.Errorf("treasureChest %v not found: %w", idStr, ErrBadRequest)
		}
		return nil, types.ErrInternal
	}

	parentUuid := uuid.Nil
	if parentId != "" {
		parent, err := s.Get(user, parentId)
		if err != nil {
			return nil, err
		}
		if parent.ParentId != uuid.Nil {
			return nil, fmt.Errorf("only a depth of 1 allowed: %w", ErrBadRequest)
		}

		children, err := s.db.GetAllByParentId(user.Id, treasureChest.Id)
		if err != nil {
			return nil, err
		}
		if len(children) > 0 {
			return nil, fmt.Errorf("only a depth of 1 allowed: %w", ErrBadRequest)
		}

		parentUuid = parent.Id
	}

	timestamp := s.clock.Now()
	treasureChest.Name = name
	treasureChest.ParentId = parentUuid
	treasureChest.UpdatedAt = &timestamp
	treasureChest.UpdatedBy = &user.Id

	err = s.db.Update(user.Id, treasureChest)
	if err != nil {
		return nil, types.ErrInternal
	}

	return treasureChest, nil
}

func (s TreasureChestImpl) Get(user *types.User, id string) (*types.TreasureChest, error) {
	treasureChestMetric.WithLabelValues("get").Inc()

	if user == nil {
		return nil, ErrUnauthorized
	}
	uuid, err := uuid.Parse(id)
	if err != nil {
		log.Error("treasureChest get: %v", err)
		return nil, fmt.Errorf("could not parse Id: %w", ErrBadRequest)
	}

	treasureChest, err := s.db.Get(user.Id, uuid)
	if err != nil {
		if err == db.ErrNotFound {
			return nil, fmt.Errorf("treasureChest %v not found: %w", id, ErrBadRequest)
		}
		return nil, types.ErrInternal
	}

	return treasureChest, nil
}

func (s TreasureChestImpl) GetAll(user *types.User) ([]*types.TreasureChest, error) {
	treasureChestMetric.WithLabelValues("get_all").Inc()
	if user == nil {
		return nil, ErrUnauthorized
	}

	treasureChests, err := s.db.GetAll(user.Id)
	if err != nil {
		return nil, types.ErrInternal
	}

	return sortTree(treasureChests), nil
}

func (s TreasureChestImpl) Delete(user *types.User, idStr string) error {
	treasureChestMetric.WithLabelValues("delete").Inc()
	if user == nil {
		return ErrUnauthorized
	}
	id, err := uuid.Parse(idStr)
	if err != nil {
		log.Error("treasureChest delete: %v", err)
		return fmt.Errorf("could not parse Id: %w", ErrBadRequest)
	}

	treasureChest, err := s.db.Get(user.Id, id)
	if err != nil {
		if err == db.ErrNotFound {
			return fmt.Errorf("treasureChest %v not found: %w", idStr, ErrBadRequest)
		}
		return types.ErrInternal
	}

	if treasureChest.UserId != user.Id {
		return types.ErrUnauthorized
	}

	children, err := s.db.GetAllByParentId(user.Id, treasureChest.Id)
	if err != nil {
		log.Error("treasureChest delete: %v", err)
		return types.ErrInternal
	}
	if len(children) > 0 {
		return fmt.Errorf("TreasureChest %v has children: %w", idStr, ErrBadRequest)
	}

	err = s.db.Delete(user.Id, treasureChest.Id)
	if err != nil {
		return types.ErrInternal
	}

	return nil
}

func sortTree(nodes []*types.TreasureChest) []*types.TreasureChest {

	var (
		roots  []*types.TreasureChest
		result []*types.TreasureChest
	)
	children := make(map[uuid.UUID][]*types.TreasureChest)

	for _, node := range nodes {
		if node.ParentId == uuid.Nil {
			roots = append(roots, node)
		} else {
			children[node.ParentId] = append(children[node.ParentId], node)
		}
	}

	for _, root := range roots {
		result = append(result, root)
		result = append(result, children[root.Id]...)
	}

	return result
}