package conf

import (
	"encoding/json"
	"fmt"
	"strings"

	"github.com/pelletier/go-toml/v2"
)

type filetype int

const (
	typeInvalid filetype = iota
	typeJSON
	typeTOML
)

// getType returns the type of the config file.
func getType(filename string) filetype {
	switch {
	case strings.HasSuffix(filename, ".json"):
		return typeJSON
	case strings.HasSuffix(filename, ".toml"):
		return typeTOML
	default:
		return typeInvalid
	}
}

// unmarshal unmarshals the given data to the given struct.
func unmarshal(ft filetype, data []byte, v any) error {
	switch ft {
	case typeJSON:
		return unmarshalJSON(data, v)
	case typeTOML:
		return unmarshalTOML(data, v)
	default:
		return ErrUnsupportedFileType
	}
}

// marshal marshals the given struct to bytes.
func marshal(ft filetype, v any) ([]byte, error) {
	switch ft {
	case typeJSON:
		return marshalJSON(v)
	case typeTOML:
		return marshalTOML(v)
	default:
		return nil, ErrUnsupportedFileType
	}
}

// unmarshalJSON unmarshals the given data to the given struct.
func unmarshalJSON(data []byte, v any) error {
	err := json.Unmarshal(data, v)
	if err != nil {
		return fmt.Errorf("cannot parse config file: %w", err)
	}

	return nil
}

// marshalJSON marshals the given struct to bytes.
func marshalJSON(v any) ([]byte, error) {
	data, err := json.MarshalIndent(v, "", "  ")
	if err != nil {
		return nil, fmt.Errorf("cannot generate config content: %w", err)
	}

	return data, nil
}

// unmarshalTOML unmarshals the given data to the given struct.
func unmarshalTOML(data []byte, v any) error {
	err := toml.Unmarshal(data, v)
	if err != nil {
		return fmt.Errorf("cannot parse config file: %w", err)
	}

	return nil
}

// marshalTOML marshals the given struct to bytes.
func marshalTOML(v any) ([]byte, error) {
	data, err := toml.Marshal(v)
	if err != nil {
		return nil, fmt.Errorf("cannot generate config content: %w", err)
	}

	return data, nil
}