// Package http implements functionality common to HTTP uploading pipelines.
package http

import (
	"crypto/tls"
	"crypto/x509"
	"fmt"
	"io"
	h "net/http"
	"os"
	"runtime"
	"strings"

	"github.com/apex/log"
	"github.com/goreleaser/goreleaser/internal/artifact"
	"github.com/goreleaser/goreleaser/internal/pipe"
	"github.com/goreleaser/goreleaser/internal/semerrgroup"
	"github.com/goreleaser/goreleaser/internal/tmpl"
	"github.com/goreleaser/goreleaser/pkg/config"
	"github.com/goreleaser/goreleaser/pkg/context"
)

const (
	// ModeBinary uploads only compiled binaries.
	ModeBinary = "binary"
	// ModeArchive uploads release archives.
	ModeArchive = "archive"
)

type asset struct {
	ReadCloser io.ReadCloser
	Size       int64
}

type assetOpenFunc func(string, *artifact.Artifact) (*asset, error)

// nolint: gochecknoglobals
var assetOpen assetOpenFunc

// TODO: fix this.
// nolint: gochecknoinits
func init() {
	assetOpenReset()
}

func assetOpenReset() {
	assetOpen = assetOpenDefault
}

func assetOpenDefault(kind string, a *artifact.Artifact) (*asset, error) {
	f, err := os.Open(a.Path)
	if err != nil {
		return nil, err
	}
	s, err := f.Stat()
	if err != nil {
		return nil, err
	}
	if s.IsDir() {
		return nil, fmt.Errorf("%s: upload failed: the asset to upload can't be a directory", kind)
	}
	return &asset{
		ReadCloser: f,
		Size:       s.Size(),
	}, nil
}

// Defaults sets default configuration options on upload structs.
func Defaults(uploads []config.Upload) error {
	for i := range uploads {
		defaults(&uploads[i])
	}
	return nil
}

func defaults(upload *config.Upload) {
	if upload.Mode == "" {
		upload.Mode = ModeArchive
	}
	if upload.Method == "" {
		upload.Method = h.MethodPut
	}
}

// CheckConfig validates an upload configuration returning a descriptive error when appropriate.
func CheckConfig(ctx *context.Context, upload *config.Upload, kind string) error {
	if upload.Target == "" {
		return misconfigured(kind, upload, "missing target")
	}

	if upload.Name == "" {
		return misconfigured(kind, upload, "missing name")
	}

	if upload.Mode != ModeArchive && upload.Mode != ModeBinary {
		return misconfigured(kind, upload, "mode must be 'binary' or 'archive'")
	}

	if _, err := getUsername(ctx, upload, kind); err != nil {
		return err
	}

	if _, err := getPassword(ctx, upload, kind); err != nil {
		return err
	}

	if upload.TrustedCerts != "" && !x509.NewCertPool().AppendCertsFromPEM([]byte(upload.TrustedCerts)) {
		return misconfigured(kind, upload, "no certificate could be added from the specified trusted_certificates configuration")
	}

	return nil
}

func getUsername(ctx *context.Context, upload *config.Upload, kind string) (string, error) {
	if upload.Username != "" {
		return upload.Username, nil
	}
	var key = fmt.Sprintf("%s_%s_USERNAME", strings.ToUpper(kind), strings.ToUpper(upload.Name))
	user, ok := ctx.Env[key]
	if !ok {
		return "", misconfigured(kind, upload, fmt.Sprintf("missing username or %s environment variable", key))
	}
	return user, nil
}

func getPassword(ctx *context.Context, upload *config.Upload, kind string) (string, error) {
	var key = fmt.Sprintf("%s_%s_SECRET", strings.ToUpper(kind), strings.ToUpper(upload.Name))
	pwd, ok := ctx.Env[key]
	if !ok {
		return "", misconfigured(kind, upload, fmt.Sprintf("missing %s environment variable", key))
	}
	return pwd, nil
}

func misconfigured(kind string, upload *config.Upload, reason string) error {
	return pipe.Skip(fmt.Sprintf("%s section '%s' is not configured properly (%s)", kind, upload.Name, reason))
}

// ResponseChecker is a function capable of validating an http server response.
// It must return and error when the response must be considered a failure.
type ResponseChecker func(*h.Response) error

// Upload does the actual uploading work.
func Upload(ctx *context.Context, uploads []config.Upload, kind string, check ResponseChecker) error {
	if ctx.SkipPublish {
		return pipe.ErrSkipPublishEnabled
	}

	// Handle every configured upload
	for _, upload := range uploads {
		upload := upload
		filters := []artifact.Filter{}
		if upload.Checksum {
			filters = append(filters, artifact.ByType(artifact.Checksum))
		}
		if upload.Signature {
			filters = append(filters, artifact.ByType(artifact.Signature))
		}
		// We support two different modes
		//	- "archive": Upload all artifacts
		//	- "binary": Upload only the raw binaries
		switch v := strings.ToLower(upload.Mode); v {
		case ModeArchive:
			// TODO: should we add source archives here too?
			filters = append(filters,
				artifact.ByType(artifact.UploadableArchive),
				artifact.ByType(artifact.LinuxPackage),
			)
		case ModeBinary:
			filters = append(filters, artifact.ByType(artifact.UploadableBinary))
		default:
			err := fmt.Errorf("%s: mode \"%s\" not supported", kind, v)
			log.WithFields(log.Fields{
				kind:   upload.Name,
				"mode": v,
			}).Error(err.Error())
			return err
		}

		var filter = artifact.Or(filters...)
		if len(upload.IDs) > 0 {
			filter = artifact.And(filter, artifact.ByIDs(upload.IDs...))
		}
		if err := uploadWithFilter(ctx, &upload, filter, kind, check); err != nil {
			return err
		}
	}

	return nil
}

func uploadWithFilter(ctx *context.Context, upload *config.Upload, filter artifact.Filter, kind string, check ResponseChecker) error {
	var artifacts = ctx.Artifacts.Filter(filter).List()
	log.Debugf("will upload %d artifacts", len(artifacts))
	var g = semerrgroup.New(ctx.Parallelism)
	for _, artifact := range artifacts {
		artifact := artifact
		g.Go(func() error {
			return uploadAsset(ctx, upload, artifact, kind, check)
		})
	}
	return g.Wait()
}

// uploadAsset uploads file to target and logs all actions.
func uploadAsset(ctx *context.Context, upload *config.Upload, artifact *artifact.Artifact, kind string, check ResponseChecker) error {
	username, err := getUsername(ctx, upload, kind)
	if err != nil {
		return err
	}

	secret, err := getPassword(ctx, upload, kind)
	if err != nil {
		return err
	}

	// Generate the target url
	targetURL, err := resolveTargetTemplate(ctx, upload, artifact)
	if err != nil {
		msg := fmt.Sprintf("%s: error while building the target url", kind)
		log.WithField("instance", upload.Name).WithError(err).Error(msg)
		return fmt.Errorf("%s: %w", msg, err)
	}

	// Handle the artifact
	asset, err := assetOpen(kind, artifact)
	if err != nil {
		return err
	}
	defer asset.ReadCloser.Close()

	// target url need to contain the artifact name unless the custom
	// artifact name is used
	if !upload.CustomArtifactName {
		if !strings.HasSuffix(targetURL, "/") {
			targetURL += "/"
		}
		targetURL += artifact.Name
	}
	log.Debugf("generated target url: %s", targetURL)

	var headers = map[string]string{}
	if upload.ChecksumHeader != "" {
		sum, err := artifact.Checksum("sha256")
		if err != nil {
			return err
		}
		headers[upload.ChecksumHeader] = sum
	}

	res, err := uploadAssetToServer(ctx, upload, targetURL, username, secret, headers, asset, check)
	if err != nil {
		msg := fmt.Sprintf("%s: upload failed", kind)
		log.WithError(err).WithFields(log.Fields{
			"instance": upload.Name,
			"username": username,
		}).Error(msg)
		return fmt.Errorf("%s: %w", msg, err)
	}
	if err := res.Body.Close(); err != nil {
		log.WithError(err).Warn("failed to close response body")
	}

	log.WithFields(log.Fields{
		"instance": upload.Name,
		"mode":     upload.Mode,
	}).Info("uploaded successful")

	return nil
}

// uploadAssetToServer uploads the asset file to target.
func uploadAssetToServer(ctx *context.Context, upload *config.Upload, target, username, secret string, headers map[string]string, a *asset, check ResponseChecker) (*h.Response, error) {
	req, err := newUploadRequest(ctx, upload.Method, target, username, secret, headers, a)
	if err != nil {
		return nil, err
	}

	return executeHTTPRequest(ctx, upload, req, check)
}

// newUploadRequest creates a new h.Request for uploading.
func newUploadRequest(ctx *context.Context, method, target, username, secret string, headers map[string]string, a *asset) (*h.Request, error) {
	req, err := h.NewRequestWithContext(ctx, method, target, a.ReadCloser)
	if err != nil {
		return nil, err
	}
	req.ContentLength = a.Size
	req.SetBasicAuth(username, secret)

	for k, v := range headers {
		req.Header.Add(k, v)
	}

	return req, err
}

func getHTTPClient(upload *config.Upload) (*h.Client, error) {
	if upload.TrustedCerts == "" {
		return h.DefaultClient, nil
	}
	pool, err := x509.SystemCertPool()
	if err != nil {
		if runtime.GOOS == "windows" {
			// on windows ignore errors until golang issues #16736 & #18609 get fixed
			pool = x509.NewCertPool()
		} else {
			return nil, err
		}
	}
	pool.AppendCertsFromPEM([]byte(upload.TrustedCerts)) // already validated certs checked by CheckConfig
	return &h.Client{
		Transport: &h.Transport{
			Proxy: h.ProxyFromEnvironment,
			TLSClientConfig: &tls.Config{ // nolint: gosec
				RootCAs: pool,
			},
		},
	}, nil
}

// executeHTTPRequest processes the http call with respect of context ctx.
func executeHTTPRequest(ctx *context.Context, upload *config.Upload, req *h.Request, check ResponseChecker) (*h.Response, error) {
	client, err := getHTTPClient(upload)
	if err != nil {
		return nil, err
	}
	log.Debugf("executing request: %s %s (headers: %v)", req.Method, req.URL, req.Header)
	resp, err := client.Do(req)
	if err != nil {
		// If we got an error, and the context has been canceled,
		// the context's error is probably more useful.
		select {
		case <-ctx.Done():
			return nil, ctx.Err()
		default:
		}
		return nil, err
	}

	defer resp.Body.Close()

	err = check(resp)
	if err != nil {
		// even though there was an error, we still return the response
		// in case the caller wants to inspect it further
		return resp, err
	}

	return resp, err
}

// resolveTargetTemplate returns the resolved target template with replaced variables
// Those variables can be replaced by the given context, goos, goarch, goarm and more.
func resolveTargetTemplate(ctx *context.Context, upload *config.Upload, artifact *artifact.Artifact) (string, error) {
	var replacements = map[string]string{}
	if upload.Mode == ModeBinary {
		// TODO: multiple archives here
		replacements = ctx.Config.Archives[0].Replacements
	}
	return tmpl.New(ctx).
		WithArtifact(artifact, replacements).
		Apply(upload.Target)
}