/*
Copyright The Helm Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package values

import (
	"io/ioutil"
	"net/url"
	"os"
	"strings"

	"github.com/pkg/errors"
	"sigs.k8s.io/yaml"

	"helm.sh/helm/v3/pkg/getter"
	"helm.sh/helm/v3/pkg/strvals"
)

type Options struct {
	ValueFiles   []string
	StringValues []string
	Values       []string
	FileValues   []string
}

// MergeValues merges values from files specified via -f/--values and directly
// via --set, --set-string, or --set-file, marshaling them to YAML
func (opts *Options) MergeValues(p getter.Providers) (map[string]interface{}, error) {
	base := map[string]interface{}{}

	// User specified a values files via -f/--values
	for _, filePath := range opts.ValueFiles {
		currentMap := map[string]interface{}{}

		bytes, err := readFile(filePath, p)
		if err != nil {
			return nil, err
		}

		if err := yaml.Unmarshal(bytes, &currentMap); err != nil {
			return nil, errors.Wrapf(err, "failed to parse %s", filePath)
		}
		// Merge with the previous map
		base = mergeMaps(base, currentMap)
	}

	// User specified a value via --set
	for _, value := range opts.Values {
		if err := strvals.ParseInto(value, base); err != nil {
			return nil, errors.Wrap(err, "failed parsing --set data")
		}
	}

	// User specified a value via --set-string
	for _, value := range opts.StringValues {
		if err := strvals.ParseIntoString(value, base); err != nil {
			return nil, errors.Wrap(err, "failed parsing --set-string data")
		}
	}

	// User specified a value via --set-file
	for _, value := range opts.FileValues {
		reader := func(rs []rune) (interface{}, error) {
			bytes, err := readFile(string(rs), p)
			return string(bytes), err
		}
		if err := strvals.ParseIntoFile(value, base, reader); err != nil {
			return nil, errors.Wrap(err, "failed parsing --set-file data")
		}
	}

	return base, nil
}

func mergeMaps(a, b map[string]interface{}) map[string]interface{} {
	out := make(map[string]interface{}, len(a))
	for k, v := range a {
		out[k] = v
	}
	for k, v := range b {
		if v, ok := v.(map[string]interface{}); ok {
			if bv, ok := out[k]; ok {
				if bv, ok := bv.(map[string]interface{}); ok {
					out[k] = mergeMaps(bv, v)
					continue
				}
			}
		}
		out[k] = v
	}
	return out
}

// readFile load a file from stdin, the local directory, or a remote file with a url.
func readFile(filePath string, p getter.Providers) ([]byte, error) {
	if strings.TrimSpace(filePath) == "-" {
		return ioutil.ReadAll(os.Stdin)
	}
	u, _ := url.Parse(filePath)

	// FIXME: maybe someone handle other protocols like ftp.
	g, err := p.ByScheme(u.Scheme)
	if err != nil {
		return ioutil.ReadFile(filePath)
	}
	data, err := g.Get(filePath, getter.WithURL(filePath))
	return data.Bytes(), err
}