package state

import (
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"sync"

	"gopkg.in/yaml.v3"

	"jagacloud/node-agent/pkg/compute/libvirt"
	"jagacloud/node-agent/pkg/containers/lxc"
)

// Store persists VM/CT specs to disk and provides simple locks per ID.
type Store struct {
	vmDir string
	ctDir string

	mu    sync.Mutex
	locks map[string]*sync.Mutex
}

func NewStore(vmDir, ctDir string) *Store {
	return &Store{vmDir: vmDir, ctDir: ctDir, locks: make(map[string]*sync.Mutex)}
}

func (s *Store) ensureDirs() error {
	for _, d := range []string{s.vmDir, s.ctDir} {
		if err := os.MkdirAll(d, 0o755); err != nil {
			return err
		}
	}
	return nil
}

// ---- Locks ----
func (s *Store) lock(id string) func() {
	s.mu.Lock()
	m, ok := s.locks[id]
	if !ok {
		m = &sync.Mutex{}
		s.locks[id] = m
	}
	s.mu.Unlock()
	m.Lock()
	return m.Unlock
}

// Lock exposes a per-ID lock; caller must defer the returned unlock function.
func (s *Store) Lock(id string) func() {
	return s.lock(id)
}

// ---- VM ----
func (s *Store) SaveVM(spec libvirt.VMSpec) error {
	if err := s.ensureDirs(); err != nil {
		return err
	}
	if spec.ID == "" && spec.Name != "" {
		spec.ID = spec.Name
	}
	if spec.ID == "" {
		return fmt.Errorf("vm id is required")
	}
	data, err := yaml.Marshal(spec)
	if err != nil {
		return err
	}
	path := filepath.Join(s.vmDir, fmt.Sprintf("%s.yaml", spec.ID))
	return os.WriteFile(path, data, 0o644)
}

func (s *Store) LoadVM(id string) (libvirt.VMSpec, error) {
	var spec libvirt.VMSpec
	path := filepath.Join(s.vmDir, fmt.Sprintf("%s.yaml", id))
	data, err := os.ReadFile(path)
	if err != nil {
		return spec, err
	}
	if err := yaml.Unmarshal(data, &spec); err != nil {
		return spec, err
	}
	if spec.ID == "" {
		spec.ID = id
	}
	return spec, nil
}

func (s *Store) ListVMs() ([]libvirt.VMSpec, error) {
	specs := []libvirt.VMSpec{}
	err := filepath.WalkDir(s.vmDir, func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			return nil
		}
		if filepath.Ext(path) != ".yaml" {
			return nil
		}
		data, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		var spec libvirt.VMSpec
		if err := yaml.Unmarshal(data, &spec); err != nil {
			return err
		}
		if spec.ID == "" {
			spec.ID = trimExt(filepath.Base(path))
		}
		specs = append(specs, spec)
		return nil
	})
	if err != nil && !os.IsNotExist(err) {
		return nil, err
	}
	return specs, nil
}

func (s *Store) DeleteVM(id string) error {
	path := filepath.Join(s.vmDir, fmt.Sprintf("%s.yaml", id))
	return os.Remove(path)
}

// ---- CT ----
func (s *Store) SaveCT(spec lxc.Spec) error {
	if err := s.ensureDirs(); err != nil {
		return err
	}
	if spec.ID == "" && spec.Name != "" {
		spec.ID = spec.Name
	}
	if spec.ID == "" {
		return fmt.Errorf("ct id is required")
	}
	if spec.RootfsPool == "" {
		return fmt.Errorf("rootfs_pool is required")
	}
	data, err := yaml.Marshal(spec)
	if err != nil {
		return err
	}
	path := filepath.Join(s.ctDir, fmt.Sprintf("%s.yaml", spec.ID))
	return os.WriteFile(path, data, 0o644)
}

func (s *Store) LoadCT(id string) (lxc.Spec, error) {
	var spec lxc.Spec
	path := filepath.Join(s.ctDir, fmt.Sprintf("%s.yaml", id))
	data, err := os.ReadFile(path)
	if err != nil {
		return spec, err
	}
	if err := yaml.Unmarshal(data, &spec); err != nil {
		return spec, err
	}
	if spec.ID == "" {
		spec.ID = id
	}
	return spec, nil
}

func (s *Store) ListCTs() ([]lxc.Spec, error) {
	specs := []lxc.Spec{}
	err := filepath.WalkDir(s.ctDir, func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			return nil
		}
		if filepath.Ext(path) != ".yaml" {
			return nil
		}
		data, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		var spec lxc.Spec
		if err := yaml.Unmarshal(data, &spec); err != nil {
			return err
		}
		if spec.ID == "" {
			spec.ID = trimExt(filepath.Base(path))
		}
		specs = append(specs, spec)
		return nil
	})
	if err != nil && !os.IsNotExist(err) {
		return nil, err
	}
	return specs, nil
}

func (s *Store) DeleteCT(id string) error {
	path := filepath.Join(s.ctDir, fmt.Sprintf("%s.yaml", id))
	return os.Remove(path)
}

func trimExt(name string) string {
	return name[:len(name)-len(filepath.Ext(name))]
}