package metadata

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"

	"github.com/sirupsen/logrus"

	"gopkg.in/yaml.v2"

	"github.com/hasura/graphql-engine/cli"
	"github.com/pkg/errors"
)

type MetadataConfig struct {
	MigrationsDirectory string
	MetadataFiles       []string

	logger *logrus.Logger
}

func New(ec *cli.ExecutionContext, baseDir string) *MetadataConfig {
	return &MetadataConfig{
		MigrationsDirectory: baseDir,
		MetadataFiles:       []string{filepath.Join(baseDir, "metadata.yaml"), filepath.Join(baseDir, "metadata.json")},
		logger:              ec.Logger,
	}
}

func (m *MetadataConfig) Validate() error {
	return nil
}

func (m *MetadataConfig) CreateFiles() error {
	return nil
}

func (m *MetadataConfig) Build(metadata *yaml.MapSlice) error {
	var metadataContent []byte
	for _, format := range []string{"yaml", "json"} {
		metadataPath, err := m.GetMetadataFilePath(format)
		if err != nil {
			return err
		}

		metadataContent, err = ioutil.ReadFile(metadataPath)
		if err != nil {
			if os.IsNotExist(err) {
				continue
			}
			return err
		}
		break
	}
	if metadataContent == nil {
		return errors.New("Unable to locate metadata.[yaml|json] file under migrations directory")
	}
	var item []yaml.MapItem
	err := yaml.Unmarshal(metadataContent, &item)
	if err != nil {
		return err
	}
	*metadata = append(*metadata, item...)
	return nil
}

func (m *MetadataConfig) Export(metadata yaml.MapSlice) (map[string][]byte, error) {
	metaByt, err := yaml.Marshal(metadata)
	if err != nil {
		return nil, errors.Wrap(err, "cannot marshal metadata")
	}
	metadataPath, err := m.GetMetadataFilePath("yaml")
	if err != nil {
		return nil, errors.Wrap(err, "cannot save metadata")
	}
	return map[string][]byte{
		metadataPath: metaByt,
	}, nil
}

func (m *MetadataConfig) GetMetadataFilePath(format string) (string, error) {
	ext := fmt.Sprintf(".%s", format)
	for _, filePath := range m.MetadataFiles {
		switch p := filepath.Ext(filePath); p {
		case ext:
			return filePath, nil
		}
	}
	return "", errors.New("unsupported file type")
}

func (m *MetadataConfig) Name() string {
	return "singleFileMetadata"
}

// GetExistingMetadataFile returns the path to the default metadata file that
// also exists, json or yaml
func (m *MetadataConfig) GetExistingMetadataFile() (string, error) {
	filename := ""
	for _, format := range []string{"yaml", "json"} {
		f, err := m.GetMetadataFilePath(format)
		if err != nil {
			return "", errors.Wrap(err, "cannot get metadata file")
		}

		filename = f
		if _, err := os.Stat(filename); os.IsNotExist(err) {
			continue
		}
		break
	}

	return filename, nil
}