package cmd

import (
	"bytes"
	"fmt"
	"os"
	"path"
	"regexp"
	"strings"
	"text/template"

	"github.com/SAP/jenkins-library/pkg/certutils"
	"github.com/SAP/jenkins-library/pkg/command"
	"github.com/SAP/jenkins-library/pkg/goget"
	piperhttp "github.com/SAP/jenkins-library/pkg/http"
	"github.com/SAP/jenkins-library/pkg/log"
	"github.com/SAP/jenkins-library/pkg/piperenv"
	"github.com/SAP/jenkins-library/pkg/piperutils"
	"github.com/SAP/jenkins-library/pkg/telemetry"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/module"
)

const (
	coverageFile                = "cover.out"
	golangUnitTestOutput        = "TEST-go.xml"
	golangIntegrationTestOutput = "TEST-integration.xml"
	golangCoberturaPackage      = "github.com/boumenot/gocover-cobertura@latest"
	golangTestsumPackage        = "gotest.tools/gotestsum@latest"
)

type golangBuildUtils interface {
	command.ExecRunner
	goget.Client

	piperutils.FileUtils
	piperhttp.Uploader

	// Add more methods here, or embed additional interfaces, or remove/replace as required.
	// The golangBuildUtils interface should be descriptive of your runtime dependencies,
	// i.e. include everything you need to be able to mock in tests.
	// Unit tests shall be executable in parallel (not depend on global state), and don't (re-)test dependencies.
}

type golangBuildUtilsBundle struct {
	*command.Command
	*piperutils.Files
	piperhttp.Uploader
	goget.Client

	// Embed more structs as necessary to implement methods or interfaces you add to golangBuildUtils.
	// Structs embedded in this way must each have a unique set of methods attached.
	// If there is no struct which implements the method you need, attach the method to
	// golangBuildUtilsBundle and forward to the implementation of the dependency.
}

func newGolangBuildUtils(config golangBuildOptions) golangBuildUtils {
	httpClientOptions := piperhttp.ClientOptions{}

	if len(config.CustomTLSCertificateLinks) > 0 {
		httpClientOptions.TransportSkipVerification = false
		httpClientOptions.TrustedCerts = config.CustomTLSCertificateLinks
	}

	httpClient := piperhttp.Client{}
	httpClient.SetOptions(httpClientOptions)

	utils := golangBuildUtilsBundle{
		Command:  &command.Command{},
		Files:    &piperutils.Files{},
		Uploader: &httpClient,
		Client: &goget.ClientImpl{
			HTTPClient: &httpClient,
		},
	}
	// Reroute command output to logging framework
	utils.Stdout(log.Writer())
	utils.Stderr(log.Writer())
	return &utils
}

func golangBuild(config golangBuildOptions, telemetryData *telemetry.CustomData) {
	// Utils can be used wherever the command.ExecRunner interface is expected.
	// It can also be used for example as a mavenExecRunner.
	utils := newGolangBuildUtils(config)

	// Error situations will be bubbled up until they reach the line below which will then stop execution
	// through the log.Entry().Fatal() call leading to an os.Exit(1) in the end.
	err := runGolangBuild(&config, telemetryData, utils)
	if err != nil {
		log.Entry().WithError(err).Fatal("execution of golang build failed")
	}
}

func runGolangBuild(config *golangBuildOptions, telemetryData *telemetry.CustomData, utils golangBuildUtils) error {
	err := prepareGolangEnvironment(config, utils)
	if err != nil {
		return err
	}

	// install test pre-requisites only in case testing should be performed
	if config.RunTests || config.RunIntegrationTests {
		if err := utils.RunExecutable("go", "install", golangTestsumPackage); err != nil {
			return fmt.Errorf("failed to install pre-requisite: %w", err)
		}
	}

	failedTests := false

	if config.RunTests {
		success, err := runGolangTests(config, utils)
		if err != nil {
			return err
		}
		failedTests = !success
	}

	if config.RunTests && config.ReportCoverage {
		if err := reportGolangTestCoverage(config, utils); err != nil {
			return err
		}
	}

	if config.RunIntegrationTests {
		success, err := runGolangIntegrationTests(config, utils)
		if err != nil {
			return err
		}
		failedTests = failedTests || !success
	}

	if failedTests {
		log.SetErrorCategory(log.ErrorTest)
		return fmt.Errorf("some tests failed")
	}

	ldflags := ""

	if len(config.LdflagsTemplate) > 0 {
		var err error
		ldflags, err = prepareLdflags(config, utils, GeneralConfig.EnvRootPath)
		if err != nil {
			return err
		}
		log.Entry().Infof("ldflags from template: '%v'", ldflags)
	}

	binaries := []string{}

	for _, architecture := range config.TargetArchitectures {
		binary, err := runGolangBuildPerArchitecture(config, utils, ldflags, architecture)

		if err != nil {
			return err
		}

		if len(binary) > 0 {
			binaries = append(binaries, binary)
		}
	}

	if config.Publish {
		if len(config.TargetRepositoryURL) == 0 {
			return fmt.Errorf("there's no target repository for binary publishing configured")
		}

		repoClientOptions := piperhttp.ClientOptions{
			Username:     config.TargetRepositoryUser,
			Password:     config.TargetRepositoryPassword,
			TrustedCerts: config.CustomTLSCertificateLinks,
		}

		utils.SetOptions(repoClientOptions)

		for _, binary := range binaries {
			log.Entry().Infof("publishing artifact '%s'", binary)

			response, err := utils.UploadFile(fmt.Sprintf("%s/%s", config.TargetRepositoryURL, binary), binary, "", nil, nil, "binary")

			if err != nil {
				return fmt.Errorf("couldn't upload artifact: %w", err)
			}

			if response.StatusCode != 200 {
				return fmt.Errorf("couldn't upload artifact, received status code %d", response.StatusCode)
			}
		}
	}

	return nil
}

func prepareGolangEnvironment(config *golangBuildOptions, utils golangBuildUtils) error {
	// configure truststore
	err := certutils.CertificateUpdate(config.CustomTLSCertificateLinks, utils, utils, "/etc/ssl/certs/ca-certificates.crt") // TODO reimplement

	if config.PrivateModules == "" {
		return nil
	}

	if config.PrivateModulesGitToken == "" {
		return fmt.Errorf("please specify a token for fetching private git modules")
	}

	// pass private repos to go process
	os.Setenv("GOPRIVATE", config.PrivateModules)

	repoURLs, err := lookupGolangPrivateModulesRepositories(config.PrivateModules, utils)

	if err != nil {
		return err
	}

	// configure credentials git shall use for pulling repos
	for _, repoURL := range repoURLs {
		if match, _ := regexp.MatchString("(?i)^https?://", repoURL); !match {
			continue
		}

		authenticatedRepoURL := strings.Replace(repoURL, "://", fmt.Sprintf("://%s@", config.PrivateModulesGitToken), 1)

		err = utils.RunExecutable("git", "config", "--global", fmt.Sprintf("url.%s.insteadOf", authenticatedRepoURL), fmt.Sprintf("%s", repoURL))
		if err != nil {
			return err
		}
	}

	return nil
}

func runGolangTests(config *golangBuildOptions, utils golangBuildUtils) (bool, error) {
	// execute gotestsum in order to have more output options
	if err := utils.RunExecutable("gotestsum", "--junitfile", golangUnitTestOutput, "--", fmt.Sprintf("-coverprofile=%v", coverageFile), "./..."); err != nil {
		exists, fileErr := utils.FileExists(golangUnitTestOutput)
		if !exists || fileErr != nil {
			log.SetErrorCategory(log.ErrorBuild)
			return false, fmt.Errorf("running tests failed - junit result missing: %w", err)
		}
		exists, fileErr = utils.FileExists(coverageFile)
		if !exists || fileErr != nil {
			log.SetErrorCategory(log.ErrorBuild)
			return false, fmt.Errorf("running tests failed - coverage output missing: %w", err)
		}
		return false, nil
	}
	return true, nil
}

func runGolangIntegrationTests(config *golangBuildOptions, utils golangBuildUtils) (bool, error) {
	// execute gotestsum in order to have more output options
	// for integration tests coverage data is not meaningful and thus not being created
	if err := utils.RunExecutable("gotestsum", "--junitfile", golangIntegrationTestOutput, "--", "-tags=integration", "./..."); err != nil {
		exists, fileErr := utils.FileExists(golangIntegrationTestOutput)
		if !exists || fileErr != nil {
			log.SetErrorCategory(log.ErrorBuild)
			return false, fmt.Errorf("running tests failed: %w", err)
		}
		return false, nil
	}
	return true, nil
}

func reportGolangTestCoverage(config *golangBuildOptions, utils golangBuildUtils) error {
	if config.CoverageFormat == "cobertura" {
		// execute gocover-cobertura in order to create cobertura report
		// install pre-requisites
		if err := utils.RunExecutable("go", "install", golangCoberturaPackage); err != nil {
			return fmt.Errorf("failed to install pre-requisite: %w", err)
		}

		coverageData, err := utils.FileRead(coverageFile)
		if err != nil {
			return fmt.Errorf("failed to read coverage file %v: %w", coverageFile, err)
		}
		utils.Stdin(bytes.NewBuffer(coverageData))

		coverageOutput := bytes.Buffer{}
		utils.Stdout(&coverageOutput)
		options := []string{}
		if config.ExcludeGeneratedFromCoverage {
			options = append(options, "-ignore-gen-files")
		}
		if err := utils.RunExecutable("gocover-cobertura", options...); err != nil {
			log.SetErrorCategory(log.ErrorTest)
			return fmt.Errorf("failed to convert coverage data to cobertura format: %w", err)
		}
		utils.Stdout(log.Writer())

		err = utils.FileWrite("cobertura-coverage.xml", coverageOutput.Bytes(), 0666)
		if err != nil {
			return fmt.Errorf("failed to create cobertura coverage file: %w", err)
		}
		log.Entry().Info("created file cobertura-coverage.xml")
	} else {
		// currently only cobertura and html format supported, thus using html as fallback
		if err := utils.RunExecutable("go", "tool", "cover", "-html", coverageFile, "-o", "coverage.html"); err != nil {
			return fmt.Errorf("failed to create html coverage file: %w", err)
		}
	}
	return nil
}

func prepareLdflags(config *golangBuildOptions, utils golangBuildUtils, envRootPath string) (string, error) {
	cpe := piperenv.CPEMap{}
	err := cpe.LoadFromDisk(path.Join(envRootPath, "commonPipelineEnvironment"))
	if err != nil {
		log.Entry().Warning("failed to load values from commonPipelineEnvironment")
	}

	log.Entry().Debugf("ldflagsTemplate in use: %v", config.LdflagsTemplate)
	tmpl, err := template.New("ldflags").Parse(config.LdflagsTemplate)
	if err != nil {
		return "", fmt.Errorf("failed to parse ldflagsTemplate '%v': %w", config.LdflagsTemplate, err)
	}

	ldflagsParams := struct {
		CPE map[string]interface{}
	}{
		CPE: map[string]interface{}(cpe),
	}
	var generatedLdflags bytes.Buffer
	err = tmpl.Execute(&generatedLdflags, ldflagsParams)
	if err != nil {
		return "", fmt.Errorf("failed to execute ldflagsTemplate '%v': %w", config.LdflagsTemplate, err)
	}

	return generatedLdflags.String(), nil
}

func runGolangBuildPerArchitecture(config *golangBuildOptions, utils golangBuildUtils, ldflags, architecture string) (string, error) {
	var binaryName string

	envVars := os.Environ()
	goos, goarch := splitTargetArchitecture(architecture)
	envVars = append(envVars, fmt.Sprintf("GOOS=%v", goos), fmt.Sprintf("GOARCH=%v", goarch))

	if !config.CgoEnabled {
		envVars = append(envVars, "CGO_ENABLED=0")
	}
	utils.SetEnv(envVars)

	buildOptions := []string{"build"}
	if len(config.Output) > 0 {
		fileExtension := ""
		if goos == "windows" {
			fileExtension = ".exe"
		}

		if len(config.ArtifactVersion) == 0 {
			binaryName = fmt.Sprintf("%v.%v-%v%v", config.Output, goos, goarch, fileExtension)
		} else {
			binaryName = fmt.Sprintf("%v-%v.%v-%v%v", config.Output, config.ArtifactVersion, goos, goarch, fileExtension)
		}

		buildOptions = append(buildOptions, "-o", binaryName)
	}
	buildOptions = append(buildOptions, config.BuildFlags...)
	buildOptions = append(buildOptions, config.Packages...)
	if len(ldflags) > 0 {
		buildOptions = append(buildOptions, "-ldflags", ldflags)
	}

	if err := utils.RunExecutable("go", buildOptions...); err != nil {
		log.Entry().Debugf("buildOptions: %v", buildOptions)
		log.SetErrorCategory(log.ErrorBuild)
		return "", fmt.Errorf("failed to run build for %v.%v: %w", goos, goarch, err)
	}
	return binaryName, nil
}

func splitTargetArchitecture(architecture string) (string, string) {
	// architecture expected to be in format os,arch due to possibleValues check of step

	architectureParts := strings.Split(architecture, ",")
	return architectureParts[0], architectureParts[1]
}

// lookupPrivateModulesRepositories returns a slice of all modules that match the given glob pattern
func lookupGolangPrivateModulesRepositories(globPattern string, utils golangBuildUtils) ([]string, error) {
	if globPattern == "" {
		return []string{}, nil
	}

	if modFileExists, err := utils.FileExists("go.mod"); err != nil {
		return nil, err
	} else if !modFileExists {
		return []string{}, nil // nothing to do
	}

	modFileContent, err := utils.FileRead("go.mod")
	if err != nil {
		return nil, err
	}

	goModFile, err := modfile.Parse("go.mod", modFileContent, nil)
	if err != nil {
		return nil, err
	} else if goModFile.Require == nil {
		return []string{}, nil // no modules referenced, nothing to do
	}

	privateModules := []string{}

	for _, goModule := range goModFile.Require {
		if !module.MatchPrefixPatterns(globPattern, goModule.Mod.Path) {
			continue
		}

		repo, err := utils.GetRepositoryURL(goModule.Mod.Path)

		if err != nil {
			return nil, err
		}

		privateModules = append(privateModules, repo)
	}
	return privateModules, nil
}