package yamlutil

import (
	"fmt"
	"io/fs"
	"os"

	"gopkg.in/yaml.v3"
)

// LoadYamlFile reads the file at the given path and unmarshals it into the
// given pointer.
func LoadYamlFile(into interface{}, path string) error {

	file, err := os.Open(path)

	if err != nil {
		return fmt.Errorf("opening file: %w", err)
	}

	defer file.Close()

	if err = yaml.NewDecoder(file).Decode(into); err != nil {
		return fmt.Errorf("decoding yaml: %w", err)
	}

	return nil
}

// WriteYamlFile encodes the given data as a yaml document, and writes it to the
// given file path, overwriting any previous data.
func WriteYamlFile(data interface{}, path string) error {

	file, err := os.OpenFile(
		path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0640,
	)

	if err != nil {
		return fmt.Errorf("opening file: %w", err)
	}

	err = yaml.NewEncoder(file).Encode(data)

	file.Close()

	if err != nil {
		return fmt.Errorf("writing/encoding file: %w", err)
	}

	return nil
}

// LoadYamlFSFile is like LoadYamlFile, but it will read the file from the given
// fs.FS instance.
func LoadYamlFSFile(into interface{}, f fs.FS, path string) error {

	body, err := fs.ReadFile(f, path)
	if err != nil {
		return fmt.Errorf("reading file from FS: %w", err)
	}

	if err := yaml.Unmarshal(body, into); err != nil {
		return fmt.Errorf("yaml unmarshaling: %w", err)
	}

	return nil
}