package data

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

	"google.golang.org/protobuf/encoding/protojson"
	"google.golang.org/protobuf/proto"
	"gopkg.in/yaml.v3"
)

func protoMap(message proto.Message) (map[string]any, error) {
	raw, err := protojson.MarshalOptions{UseProtoNames: true}.Marshal(message)
	if err != nil {
		return nil, err
	}
	var value map[string]any
	if err = json.Unmarshal(raw, &value); err != nil {
		return nil, err
	}
	delete(value, "config_path")
	return value, nil
}

func setYAMLMapping(node *yaml.Node, key string, value any) error {
	if node.Kind == yaml.DocumentNode {
		node = node.Content[0]
	}
	if node.Kind != yaml.MappingNode {
		return fmt.Errorf("configuration root is not a mapping")
	}
	raw, err := yaml.Marshal(value)
	if err != nil {
		return err
	}
	var replacement yaml.Node
	if err = yaml.Unmarshal(raw, &replacement); err != nil {
		return err
	}
	for i := 0; i < len(node.Content); i += 2 {
		if node.Content[i].Value == key {
			node.Content[i+1] = replacement.Content[0]
			return nil
		}
	}
	node.Content = append(node.Content, &yaml.Node{Kind: yaml.ScalarNode, Value: key}, replacement.Content[0])
	return nil
}

func (d *Data) persistConfig() error {
	if d.admin == nil || d.admin.ConfigPath == "" {
		return nil
	}
	raw, err := os.ReadFile(d.admin.ConfigPath)
	if err != nil {
		return err
	}
	var document yaml.Node
	if err = yaml.Unmarshal(raw, &document); err != nil {
		return err
	}
	dataValue, err := protoMap(d.config)
	if err != nil {
		return err
	}
	adminValue, err := protoMap(d.admin)
	if err != nil {
		return err
	}
	if err = setYAMLMapping(&document, "data", dataValue); err != nil {
		return err
	}
	if err = setYAMLMapping(&document, "admin", adminValue); err != nil {
		return err
	}
	output, err := yaml.Marshal(&document)
	if err != nil {
		return err
	}
	if err = os.MkdirAll(filepath.Dir(d.admin.ConfigPath), 0o755); err != nil {
		return err
	}
	temporary, err := os.CreateTemp(filepath.Dir(d.admin.ConfigPath), ".kra-config-*.yaml")
	if err != nil {
		return err
	}
	tempName := temporary.Name()
	defer os.Remove(tempName)
	if _, err = temporary.Write(output); err != nil {
		_ = temporary.Close()
		return err
	}
	if err = temporary.Chmod(0o600); err != nil {
		_ = temporary.Close()
		return err
	}
	if err = temporary.Close(); err != nil {
		return err
	}
	return os.Rename(tempName, d.admin.ConfigPath)
}