package storage

import (
	"errors"
	"fmt"
	"sync"

	"gitea.avt.data-center.id/othman.suseno/atlas/internal/models"
)

var (
	ErrISCSITargetNotFound = errors.New("iSCSI target not found")
	ErrISCSITargetExists   = errors.New("iSCSI target already exists")
	ErrLUNNotFound         = errors.New("LUN not found")
	ErrLUNExists           = errors.New("LUN already exists")
)

// ISCSIStore manages iSCSI targets and LUNs
type ISCSIStore struct {
	mu      sync.RWMutex
	targets map[string]*models.ISCSITarget
	nextID  int
}

// NewISCSIStore creates a new iSCSI store
func NewISCSIStore() *ISCSIStore {
	return &ISCSIStore{
		targets: make(map[string]*models.ISCSITarget),
		nextID:  1,
	}
}

// List returns all iSCSI targets
func (s *ISCSIStore) List() []models.ISCSITarget {
	s.mu.RLock()
	defer s.mu.RUnlock()

	targets := make([]models.ISCSITarget, 0, len(s.targets))
	for _, target := range s.targets {
		targets = append(targets, *target)
	}
	return targets
}

// Get returns a target by ID
func (s *ISCSIStore) Get(id string) (*models.ISCSITarget, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	target, ok := s.targets[id]
	if !ok {
		return nil, ErrISCSITargetNotFound
	}
	return target, nil
}

// GetByIQN returns a target by IQN
func (s *ISCSIStore) GetByIQN(iqn string) (*models.ISCSITarget, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	for _, target := range s.targets {
		if target.IQN == iqn {
			return target, nil
		}
	}
	return nil, ErrISCSITargetNotFound
}

// Create creates a new iSCSI target
func (s *ISCSIStore) Create(iqn string, initiators []string) (*models.ISCSITarget, error) {
	s.mu.Lock()
	defer s.mu.Unlock()

	// Check if IQN already exists
	for _, target := range s.targets {
		if target.IQN == iqn {
			return nil, ErrISCSITargetExists
		}
	}

	id := fmt.Sprintf("iscsi-%d", s.nextID)
	s.nextID++

	target := &models.ISCSITarget{
		ID:         id,
		IQN:        iqn,
		LUNs:       []models.LUN{},
		Initiators: initiators,
		Enabled:    true,
	}

	s.targets[id] = target
	return target, nil
}

// Update updates an existing target
func (s *ISCSIStore) Update(id string, initiators []string, enabled bool) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	target, ok := s.targets[id]
	if !ok {
		return ErrISCSITargetNotFound
	}

	target.Enabled = enabled
	if initiators != nil {
		target.Initiators = initiators
	}

	return nil
}

// Delete removes a target
func (s *ISCSIStore) Delete(id string) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	if _, ok := s.targets[id]; !ok {
		return ErrISCSITargetNotFound
	}

	delete(s.targets, id)
	return nil
}

// AddLUN adds a LUN to a target
func (s *ISCSIStore) AddLUN(targetID string, zvol string, size uint64) (*models.LUN, error) {
	s.mu.Lock()
	defer s.mu.Unlock()

	target, ok := s.targets[targetID]
	if !ok {
		return nil, ErrISCSITargetNotFound
	}

	// Check if ZVOL already mapped
	for _, lun := range target.LUNs {
		if lun.ZVOL == zvol {
			return nil, ErrLUNExists
		}
	}

	// Find next available LUN ID
	lunID := 0
	for _, lun := range target.LUNs {
		if lun.ID >= lunID {
			lunID = lun.ID + 1
		}
	}

	lun := models.LUN{
		ID:      lunID,
		ZVOL:    zvol,
		Size:    size,
		Backend: "zvol",
	}

	target.LUNs = append(target.LUNs, lun)
	return &lun, nil
}

// RemoveLUN removes a LUN from a target
func (s *ISCSIStore) RemoveLUN(targetID string, lunID int) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	target, ok := s.targets[targetID]
	if !ok {
		return ErrISCSITargetNotFound
	}

	for i, lun := range target.LUNs {
		if lun.ID == lunID {
			target.LUNs = append(target.LUNs[:i], target.LUNs[i+1:]...)
			return nil
		}
	}

	return ErrLUNNotFound
}