package saltyim

import (
	"encoding/json"
	"fmt"
	"io"
	"os"

	sync "github.com/sasha-s/go-deadlock"
)

// DefaultState returns a default state file
func DefaultState() string {
	return os.ExpandEnv("$HOME/.config/salty/state.json")
}

type State struct {
	sync.RWMutex

	Indicies map[string]int64
}

func NewState() *State {
	return &State{
		Indicies: make(map[string]int64),
	}
}

func (s *State) GetIndex(name string) int64 {
	s.RLock()
	defer s.RUnlock()

	return s.Indicies[name]
}

func (s *State) SetIndex(name string, index int64) {
	s.Lock()
	defer s.Unlock()

	s.Indicies[name] = index
}

func (s *State) Bytes() ([]byte, error) {
	s.Lock()
	defer s.Unlock()

	data, err := json.Marshal(s)
	if err != nil {
		return nil, fmt.Errorf("error encoding state: %w", err)
	}

	return data, nil
}

func (s *State) Save(fn string) error {
	data, err := s.Bytes()
	if err != nil {
		return err
	}

	if err := os.WriteFile(fn, data, 0644); err != nil {
		return fmt.Errorf("error writing state file %s: %w", fn, err)
	}

	return nil
}

func LoadState(r io.Reader) (*State, error) {
	var state *State

	data, err := io.ReadAll(r)
	if err != nil {
		return nil, fmt.Errorf("error reading state: %w", err)
	}

	if err := json.Unmarshal(data, &state); err != nil {
		return nil, fmt.Errorf("error reading state: %w", err)
	}

	return state, nil
}