package settings

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

// LoadNodes reads and parses nodes.json from dir.
func LoadNodes(dir string) (NodeStore, error) {
	path := filepath.Join(dir, NodesFileName)
	payload, err := os.ReadFile(path)
	if err != nil {
		return NodeStore{}, err
	}

	var store NodeStore
	if err := json.Unmarshal(payload, &store); err != nil {
		return NodeStore{}, fmt.Errorf("parse nodes: %w", err)
	}
	if store.Nodes == nil {
		store.Nodes = []Node{}
	}
	return store, nil
}

// LoadNodesOrEmpty returns an empty store when nodes.json is missing.
func LoadNodesOrEmpty(dir string) (NodeStore, error) {
	store, err := LoadNodes(dir)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return NodeStore{Nodes: []Node{}}, nil
		}
		return NodeStore{}, err
	}
	return store, nil
}

// SaveNodes writes nodes.json to dir with mode 0640.
func SaveNodes(dir string, store NodeStore) error {
	if err := ensureConfigDir(dir); err != nil {
		return err
	}
	if store.Nodes == nil {
		store.Nodes = []Node{}
	}

	payload, err := json.MarshalIndent(store, "", "  ")
	if err != nil {
		return fmt.Errorf("encode nodes: %w", err)
	}
	payload = append(payload, '\n')

	path := filepath.Join(dir, NodesFileName)
	if err := os.WriteFile(path, payload, 0o640); err != nil {
		return fmt.Errorf("write nodes: %w", err)
	}
	return nil
}

// LoadNodeKeys decrypts node-keys.enc from dir using key.
func LoadNodeKeys(dir string, key []byte) (NodeKeyStore, error) {
	var store NodeKeyStore
	if err := loadEncryptedJSON(dir, NodeKeysFileName, key, &store); err != nil {
		return NodeKeyStore{}, err
	}
	if store.Keys == nil {
		store.Keys = []NodeKeyEntry{}
	}
	return store, nil
}

// LoadNodeKeysOrEmpty returns an empty store when node-keys.enc is missing.
func LoadNodeKeysOrEmpty(dir string, key []byte) (NodeKeyStore, error) {
	store, err := LoadNodeKeys(dir, key)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return NodeKeyStore{Keys: []NodeKeyEntry{}}, nil
		}
		return NodeKeyStore{}, err
	}
	return store, nil
}

// SaveNodeKeys encrypts the node key store and writes node-keys.enc.
func SaveNodeKeys(dir string, store NodeKeyStore, key []byte) error {
	if store.Keys == nil {
		store.Keys = []NodeKeyEntry{}
	}
	return saveEncryptedJSON(dir, NodeKeysFileName, key, store)
}