package cicd

import (
	"bufio"
	"crypto/md5"
	"encoding/base64"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"

	"geeks-accelerator/oss/saas-starter-kit/internal/platform/tests"
	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awserr"
	"github.com/aws/aws-sdk-go/service/ecr"
	"github.com/aws/aws-sdk-go/service/s3/s3manager"
	"github.com/pborman/uuid"
	"github.com/pkg/errors"
	"gopkg.in/go-playground/validator.v9"
)

// ServiceBuildFlags defines the flags used for executing a service build.
type ServiceBuildFlags struct {
	// Required flags.
	ServiceName string `validate:"required" example:"web-api"`
	Env         string `validate:"oneof=dev stage prod" example:"dev"`

	// Optional flags.
	ProjectRoot         string `validate:"omitempty" example:"."`
	ProjectName         string ` validate:"omitempty" example:"example-project"`
	DockerFile          string `validate:"omitempty" example:"./cmd/web-api/Dockerfile"`
	CommitRef           string `validate:"omitempty" example:"master@1ecfd275"`
	S3BucketPrivateName string `validate:"omitempty" example:"saas-example-project-private"`
	BuildDir            string `validate:"omitempty" example:"."`
	NoCache             bool   `validate:"omitempty" example:"false"`
	NoPush              bool   `validate:"omitempty" example:"false"`
	IsLambda            bool   `validate:"omitempty" example:"false"`
}

// serviceBuildRequest defines the details needed to execute a service build.
type serviceBuildRequest struct {
	*serviceRequest

	EcrRepositoryName      string `validate:"required"`
	EcrRepository          *ecr.CreateRepositoryInput
	EcrRepositoryMaxImages int `validate:"omitempty"`

	BuildDir            string `validate:"omitempty" example:""`
	CommitRef           string `validate:"omitempty"`
	S3BucketPrivateName string `validate:"omitempty"`
	NoCache             bool   `validate:"omitempty"`
	NoPush              bool   `validate:"omitempty"`
	IsLambda            bool   `validate:"omitempty"`

	flags ServiceBuildFlags
}

// NewServiceBuildRequest generates a new request for executing build of a single service for a given set of CLI flags.
func NewServiceBuildRequest(log *log.Logger, flags ServiceBuildFlags) (*serviceBuildRequest, error) {

	// Validates specified CLI flags map to struct successfully.
	log.Println("Validate flags.")
	{
		errs := validator.New().Struct(flags)
		if errs != nil {
			return nil, errs
		}
		log.Printf("\t%s\tFlags ok.", tests.Success)
	}

	// Generate a deploy request using CLI flags and AWS credentials.
	log.Println("Generate deploy request.")
	var req serviceBuildRequest
	{
		// Define new service request.
		sr := &serviceRequest{
			ServiceName: flags.ServiceName,
			Env:         flags.Env,
			ProjectRoot: flags.ProjectRoot,
			ProjectName: flags.ProjectName,
			DockerFile:  flags.DockerFile,
		}
		if err := sr.init(log); err != nil {
			return nil, err
		}

		req = serviceBuildRequest{
			serviceRequest: sr,

			CommitRef:           flags.CommitRef,
			S3BucketPrivateName: flags.S3BucketPrivateName,
			BuildDir:            flags.BuildDir,
			NoCache:             flags.NoCache,
			NoPush:              flags.NoPush,
			IsLambda:            flags.IsLambda,

			flags: flags,
		}

		if req.BuildDir == "" {
			req.BuildDir = req.ProjectRoot
		}

		// Set default AWS ECR Repository Name.
		req.EcrRepositoryName = ecrRepositoryName(req.ProjectName)
		req.EcrRepository = &ecr.CreateRepositoryInput{
			RepositoryName: aws.String(req.EcrRepositoryName),
			Tags: []*ecr.Tag{
				&ecr.Tag{Key: aws.String(awsTagNameProject), Value: aws.String(req.ProjectName)},
				&ecr.Tag{Key: aws.String(awsTagNameEnv), Value: aws.String(req.Env)},
			},
		}
		log.Printf("\t\t\tSet ECR Repository Name to '%s'.", req.EcrRepositoryName)

		// Set default AWS ECR Regsistry Max Images.
		req.EcrRepositoryMaxImages = defaultAwsRegistryMaxImages
		log.Printf("\t\t\tSet ECR Regsistry Max Images to '%d'.", req.EcrRepositoryMaxImages)

		// Get the default commit ref.
		if req.CommitRef == "" {
			if ev := os.Getenv("CI_COMMIT_TAG"); ev != "" {
				req.CommitRef = "tag-" + ev
			} else if ev := os.Getenv("CI_COMMIT_REF_NAME"); ev != "" {
				req.CommitRef = "branch-" + ev
			}

			if ev := os.Getenv("CI_COMMIT_SHORT_SHA"); ev != "" {
				req.CommitRef = req.CommitRef + "@" + ev
			}
		}

	}

	return &req, nil
}

// Run is the main entrypoint for building a service for a given target environment.
func ServiceBuild(log *log.Logger, req *serviceBuildRequest) error {

	// Load the AWS ECR repository. Try to find by name else create new one.
	var dockerLoginCmd []string
	{
		log.Println("ECR - Get or create repository.")

		svc := ecr.New(req.awsSession())

		// First try to find ECR repository by name.
		var awsRepo *ecr.Repository
		descRes, err := svc.DescribeRepositories(&ecr.DescribeRepositoriesInput{
			RepositoryNames: []*string{aws.String(req.EcrRepositoryName)},
		})
		if err != nil {
			if aerr, ok := err.(awserr.Error); !ok || aerr.Code() != ecr.ErrCodeRepositoryNotFoundException {
				return errors.Wrapf(err, "failed to describe repository '%s'", req.EcrRepositoryName)
			}
		} else if len(descRes.Repositories) > 0 {
			awsRepo = descRes.Repositories[0]
		}

		if awsRepo == nil {
			// If no repository was found, create one.
			createRes, err := svc.CreateRepository(req.EcrRepository)
			if err != nil {
				return errors.Wrapf(err, "failed to create repository '%s'", req.EcrRepositoryName)
			}
			awsRepo = createRes.Repository
			log.Printf("\t\tCreated: %s.", *awsRepo.RepositoryArn)
		} else {
			log.Printf("\t\tFound: %s.", *awsRepo.RepositoryArn)

			log.Println("\t\tChecking old ECR images.")
			delIds, err := EcrPurgeImages(req)
			if err != nil {
				return err
			}

			// Since ECR has max number of repository images, need to delete old ones so can stay under limit.
			// If there are image IDs to delete, delete them.
			if len(delIds) > 0 {
				log.Printf("\t\tDeleted %d images that exceeded limit of %d", len(delIds), req.EcrRepositoryMaxImages)
				for _, imgId := range delIds {
					log.Printf("\t\t\t%s", *imgId.ImageTag)
				}
			}
		}

		req.ReleaseImage = releaseImage(req.Env, req.ServiceName, *awsRepo.RepositoryUri)
		if err != nil {
			return err
		}

		log.Printf("\t\trelease image: %s", req.ReleaseImage)
		log.Printf("\t%s\tRelease image valid.", tests.Success)

		log.Println("ECR - Retrieve authorization token used for docker login.")

		// Get the credentials necessary for logging into the AWS Elastic Container Registry
		// made available with the AWS access key and AWS secret access keys.
		res, err := svc.GetAuthorizationToken(&ecr.GetAuthorizationTokenInput{})
		if err != nil {
			return errors.Wrap(err, "failed to get ecr authorization token")
		}

		authToken, err := base64.StdEncoding.DecodeString(*res.AuthorizationData[0].AuthorizationToken)
		if err != nil {
			return errors.Wrap(err, "failed to base64 decode ecr authorization token")
		}
		pts := strings.Split(string(authToken), ":")
		user := pts[0]
		pass := pts[1]

		dockerLoginCmd = []string{
			"docker",
			"login",
			"-u", user,
			"-p", pass,
			*res.AuthorizationData[0].ProxyEndpoint,
		}

		log.Printf("\t%s\tdocker login ok.", tests.Success)
	}

	// Once we can access the repository in ECR, do the docker build.
	{
		log.Printf("Starting docker build %s\n", req.ReleaseImage)

		var dockerFile string
		dockerPath := filepath.Join(req.BuildDir, req.DockerFile)
		if _, err := os.Stat(dockerPath); err == nil {
			dockerFile = req.DockerFile
		} else {
			dockerPath = req.DockerFile

			dockerFile, err = filepath.Rel(req.BuildDir, dockerPath)
			if err != nil {
				return errors.Wrapf(err, "Failed parse relative path for %s from %s", dockerPath, req.BuildDir)
			}
		}

		// Name of the first build stage declared in the docckerFile.
		var buildStageName string

		// When the dockerFile is multistage, caching can be applied. Scan the dockerFile for the first stage.
		// FROM golang:1.12.6-alpine3.9 AS build_base
		var buildBaseImageTag string
		{
			file, err := os.Open(dockerPath)
			if err != nil {
				log.Fatal(err)
			}
			defer file.Close()

			// List of lines in the dockerfile for the first stage. This will be used to tag the image to help ensure
			// any changes to the lines associated with the first stage force cache to be reset.
			var stageLines []string

			// Loop through all the lines in the Dockerfile searching for the lines associated with the first build stage.
			scanner := bufio.NewScanner(file)
			for scanner.Scan() {
				line := scanner.Text()

				lineLower := strings.ToLower(line)

				if strings.HasPrefix(lineLower, "from ") {
					if buildStageName != "" {
						// Only need to scan all the lines for the first build stage. Break when reach next FROM.
						break
					} else if !strings.Contains(lineLower, " as ") {
						// Caching is only supported if the first FROM has a name.
						log.Printf("\t\t\tSkipping stage cache, build stage not detected.\n")
						break
					}

					buildStageName = strings.TrimSpace(strings.Split(lineLower, " as ")[1])
					stageLines = append(stageLines, line)
				} else if buildStageName != "" {
					stageLines = append(stageLines, line)
				}
			}

			if err := scanner.Err(); err != nil {
				return errors.WithStack(err)
			}

			// If we have detected a build stage, then generate the appropriate tag.
			if buildStageName != "" {
				log.Printf("\t\tFound build stage %s for caching.\n", buildStageName)

				// Generate a checksum for the lines associated with the build stage.
				buildBaseHashPts := []string{
					fmt.Sprintf("%x", md5.Sum([]byte(strings.Join(stageLines, "\n")))),
				}

				switch buildStageName {
				case "build_base_golang":
					// Compute the checksum for the go.mod file.
					goSumPath := filepath.Join(req.ProjectRoot, "go.sum")
					goSumDat, err := ioutil.ReadFile(goSumPath)
					if err != nil {
						return errors.Wrapf(err, "Failed parse relative path for %s from %s", req.DockerFile, req.ProjectRoot)
					}
					buildBaseHashPts = append(buildBaseHashPts, fmt.Sprintf("%x", md5.Sum(goSumDat)))
				}

				// Combine all the checksums to be used to tag the target build stage.
				buildBaseHash := fmt.Sprintf("%x", md5.Sum([]byte(strings.Join(buildBaseHashPts, "|"))))

				// New stage image tag.
				buildBaseImageTag = buildStageName + "-" + buildBaseHash[0:8]
			}
		}

		var cmds [][]string

		// Enabling caching of the first build stage defined in the dockerFile.
		var buildBaseImage string
		if !req.NoCache && buildBaseImageTag != "" {
			var pushTargetImg bool
			if ciReg := os.Getenv("CI_REGISTRY"); ciReg != "" {
				cmds = append(cmds, []string{
					"docker", "login",
					"-u", os.Getenv("CI_REGISTRY_USER"),
					"-p", os.Getenv("CI_REGISTRY_PASSWORD"),
					ciReg})

				buildBaseImage = os.Getenv("CI_REGISTRY_IMAGE") + ":" + buildBaseImageTag
				pushTargetImg = true
			} else {
				buildBaseImage = req.ProjectName + ":" + req.Env + "-" + req.ServiceName + "-" + buildBaseImageTag
			}

			cmds = append(cmds, []string{"docker", "pull", buildBaseImage})

			cmds = append(cmds, []string{
				"docker", "build",
				"--file=" + dockerFile,
				"--cache-from", buildBaseImage,
				"--build-arg", "service=" + req.ServiceName,
				"--build-arg", "env=" + req.Env,
				"-t", buildBaseImage,
				"--target", buildStageName,
				".",
			})

			if pushTargetImg {
				cmds = append(cmds, []string{"docker", "push", buildBaseImage})
			}
		}

		// The initial build command slice.
		buildCmd := []string{
			"docker", "build",
			"--file=" + dockerFile,
			"--build-arg", "service=" + req.ServiceName,
			"--build-arg", "env=" + req.Env,
			"--build-arg", "commit_ref=" + req.CommitRef,
			"--build-arg", "swagInit=1",
			"-t", req.ReleaseImage,
		}

		// Append additional build flags.
		if req.NoCache {
			buildCmd = append(buildCmd, "--no-cache")
		} else if buildBaseImage != "" {
			buildCmd = append(buildCmd, "--cache-from", buildBaseImage)
		}

		// Finally append the build context as the current directory since os.Exec will use the project root as
		// the working directory.
		buildCmd = append(buildCmd, ".")

		cmds = append(cmds, buildCmd)

		s3Files := make(map[string]*s3manager.UploadInput)
		if req.NoPush == false {
			if req.IsLambda {

				lambdaS3Key := LambdaS3KeyFromReleaseImage(req.ReleaseImage)

				tmpDir := os.TempDir()
				lambdaZip := filepath.Join(tmpDir, filepath.Base(lambdaS3Key))

				containerName := uuid.NewRandom().String()

				cmds = append(cmds, []string{"docker", "create", "-ti", "--name", containerName, req.ReleaseImage, "bash"})
				cmds = append(cmds, []string{"docker", "cp", containerName + ":/var/task", tmpDir})
				cmds = append(cmds, []string{"docker", "rm", containerName})
				cmds = append(cmds, []string{"cd", tmpDir + "/task"})
				cmds = append(cmds, []string{"zip", "-r", lambdaZip, "."})

				s3Files[lambdaZip] = &s3manager.UploadInput{
					Bucket: &req.S3BucketPrivateName,
					Key:    &lambdaS3Key,
				}

			} else {
				cmds = append(cmds, dockerLoginCmd)
				cmds = append(cmds, []string{"docker", "push", req.ReleaseImage})
			}
		}

		for _, cmd := range cmds {
			var logCmd string
			if len(cmd) >= 2 && cmd[1] == "login" {
				logCmd = strings.Join(cmd[0:2], " ")
			} else {
				logCmd = strings.Join(cmd, " ")
			}

			log.Printf("\t\t%s\n", logCmd)

			err := execCmds(log, req.BuildDir, cmd)
			if err != nil {
				if len(cmd) > 2 && cmd[1] == "pull" {
					log.Printf("\t\t\tSkipping pull - %s\n", err.Error())
				} else {
					return errors.Wrapf(err, "Failed to exec %s", strings.Join(cmd, " "))
				}
			}
		}

		if s3Files != nil && len(s3Files) > 0 {
			// Create an uploader with the session and default options
			uploader := s3manager.NewUploader(req.awsSession())

			// Perform an upload.
			for lf, upParams := range s3Files {
				f, err := os.Open(lf)
				if err != nil {
					return errors.Wrapf(err, "Failed open file to %s", lf)
				}
				upParams.Body = f

				_, err = uploader.Upload(upParams)
				if err != nil {
					return errors.Wrapf(err, "Failed upload file to %s", *upParams.Key)
				}

				log.Printf("\t\tUploaded %s to s3://%s/%s\n", lf, *upParams.Bucket, *upParams.Key)
			}
		}

		log.Printf("\t%s\tbuild complete.\n", tests.Success)
	}

	return nil
}