// Copyright 2019 DeepMap, Inc.

//

// 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 codegen

import (

	"bufio"

	"bytes"

	"compress/gzip"

	"encoding/base64"

	"fmt"

	"text/template"

	"github.com/getkin/kin-openapi/openapi3"

)

// This generates a gzipped, base64 encoded JSON representation of the

// swagger definition, which we embed inside the generated code.

func GenerateInlinedSpec(t *template.Template, swagger *openapi3.Swagger) (string, error) {

	// Marshal to json

	encoded, err := swagger.MarshalJSON()

	if err != nil {

		return "", fmt.Errorf("error marshaling swagger: %s", err)

	}

	// gzip

	var buf bytes.Buffer

	zw, err := gzip.NewWriterLevel(&buf, gzip.BestCompression)

	if err != nil {

		return "", fmt.Errorf("error creating gzip compressor: %s", err)

	}

	_, err = zw.Write(encoded)

	if err != nil {

		return "", fmt.Errorf("error gzipping swagger file: %s", err)

	}

	err = zw.Close()

	if err != nil {

		return "", fmt.Errorf("error gzipping swagger file: %s", err)

	}

	str := base64.StdEncoding.EncodeToString(buf.Bytes())

	var parts []string

	const width = 80

	// Chop up the string into an array of strings.

	for len(str) > width {

		part := str[0:width]

		parts = append(parts, part)

		str = str[width:]

	}

	if len(str) > 0 {

		parts = append(parts, str)

	}

	// Generate inline code.

	buf.Reset()

	w := bufio.NewWriter(&buf)

	err = t.ExecuteTemplate(w, "inline.tmpl", parts)

	if err != nil {

		return "", fmt.Errorf("error generating inlined spec: %s", err)

	}

	err = w.Flush()

	if err != nil {

		return "", fmt.Errorf("error flushing output buffer for inlined spec: %s", err)

	}

	return buf.String(), nil

}