package distworker

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
)

type workerState struct {
	Token           string `json:"token"`
	WorkerID        string `json:"worker_id"`
	VerificationKey string `json:"verification_key"`
	SigningKeyID    string `json:"signing_key_id"`
	AccountID       int64  `json:"account_id"`
	ConfigVersion   int64  `json:"config_version"`
	ConfigPayload   string `json:"config_payload"`
}

func loadWorkerState(path string) (workerState, error) {
	if path == "" {
		return workerState{}, nil
	}
	if !filepath.IsAbs(path) {
		return workerState{}, fmt.Errorf("worker state file must be absolute")
	}
	if info, err := os.Stat(filepath.Dir(path)); err != nil || !info.IsDir() || info.Mode().Perm() != 0o700 {
		return workerState{}, fmt.Errorf("worker state directory must have mode 0700")
	}
	info, err := os.Stat(path)
	if os.IsNotExist(err) {
		return workerState{}, nil
	}
	if err != nil {
		return workerState{}, err
	}
	if info.Mode().Perm() != 0o600 {
		return workerState{}, fmt.Errorf("worker state file must have mode 0600")
	}
	data, err := os.ReadFile(path)
	if err != nil {
		return workerState{}, err
	}
	var state workerState
	if err := json.Unmarshal(data, &state); err != nil {
		return workerState{}, err
	}
	return state, nil
}

func saveWorkerState(path string, state workerState) error {
	if path == "" {
		return nil
	}
	if !filepath.IsAbs(path) {
		return fmt.Errorf("worker state file must be absolute")
	}
	if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
		return err
	}
	if info, err := os.Stat(filepath.Dir(path)); err != nil || !info.IsDir() || info.Mode().Perm() != 0o700 {
		return fmt.Errorf("worker state directory must have mode 0700")
	}
	data, err := json.Marshal(state)
	if err != nil {
		return err
	}
	tmp, err := os.CreateTemp(filepath.Dir(path), ".state-")
	if err != nil {
		return err
	}
	tmpName := tmp.Name()
	defer os.Remove(tmpName)
	if err := tmp.Chmod(0o600); err != nil {
		_ = tmp.Close()
		return err
	}
	if _, err := tmp.Write(data); err != nil {
		_ = tmp.Close()
		return err
	}
	if err := tmp.Sync(); err != nil {
		_ = tmp.Close()
		return err
	}
	if err := tmp.Close(); err != nil {
		return err
	}
	if err := os.Rename(tmpName, path); err != nil {
		return err
	}
	dir, err := os.Open(filepath.Dir(path))
	if err != nil {
		return err
	}
	defer dir.Close()
	return dir.Sync()
}