Lithium/pipelines/pipeline.go

package pipelines

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io/fs"
	"log"
	"os"
	"path/filepath"

	"github.com/disintegration/imaging"
	"github.com/geplauder/lithium/storage"
)

// Pipelines

const (
	Image PipelineType = iota
	Video
)

type PipelineType int

type IPipeline interface {
	GetName() string
	GetSlug() string
	GetType() PipelineType
	GetSteps() []Step
	Run(string, string, storage.IStorageProvider) (string, error)
}

type Pipeline struct {
	Name           string       `json:"name" faker:"name"`
	Slug           string       `json:"slug" faker:"word"`
	Type           PipelineType `json:"type" faker:"-"`
	RemoveMetadata bool         `json:"remove_metadata" faker:"-"`
	Steps          []Step       `json:"steps" faker:"-"`
	Output         struct {
		Format  string `json:"format"`
		Quality int    `json:"quality"`
	} `json:"output" faker:"-"`
}

func (p Pipeline) Run(srcPath, bucketName string, storageProvider storage.IStorageProvider) (string, error) {
	src, err := imaging.Open(storageProvider.GetPath(bucketName, srcPath))
	if err != nil {
		return "", errors.New(fmt.Sprintf("error opening file for processing: %s", err))
	}

	for _, step := range p.GetSteps() {
		runner, err := step.GetExecutable()
		if err != nil {
			return "", err
		}

		src, err = runner.Execute(src)
		if err != nil {
			return "", err
		}
	}

	outputFormat := p.Output.Format
	if outputFormat == "" {
		outputFormat = "jpg"
	}

	format, err := imaging.FormatFromExtension(outputFormat)
	if err != nil {
		return "", errors.New(fmt.Sprintf("output format '%s' is not supported", outputFormat))
	}

	var options []imaging.EncodeOption

	if p.Output.Quality != 0 {
		options = append(options, imaging.JPEGQuality(p.Output.Quality))
	}

	// encode image to io buffer
	buffer := new(bytes.Buffer)
	if err := imaging.Encode(buffer, src, format, options...); err != nil {
		return "", err
	}

	const fileName = "output.jpg" // TODO make variable

	_, err = storageProvider.StoreRaw(bucketName, fileName, buffer.Bytes())
	if err != nil {
		return "", err
	}

	return fileName, nil
}

func (p Pipeline) GetName() string {
	return p.Name
}

func (p Pipeline) GetSlug() string {
	return p.Slug
}

func (p Pipeline) GetType() PipelineType {
	return p.Type
}

func (p Pipeline) GetSteps() []Step {
	return p.Steps
}

type ImagePipeline struct {
	Pipeline
}

type VideoPipeline struct {
	Pipeline
}

// Deserialization

func DeserializePipelines(pipelines [][]byte) []IPipeline {
	var values []IPipeline

	for _, pipeline := range pipelines {
		var deserializedObject Pipeline
		err := json.Unmarshal(pipeline, &deserializedObject)
		if err != nil {
			log.Fatalf("Could not deserialize pipelines config: %s", err)
		}
		values = append(values, deserializedObject)
	}

	return values
}

func LoadPipelines() []IPipeline {
	var files [][]byte

	path, _ := os.Getwd()

	err := filepath.Walk(path+"/config", func(path string, info fs.FileInfo, err error) error {
		if err == nil && info.IsDir() == false {
			data, _ := os.ReadFile(path)
			files = append(files, data)
		}

		return nil
	})

	if err != nil {
		panic(err)
	}

	return DeserializePipelines(files)
}