package client

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"io"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/containerd/containerd/content"
	contentlocal "github.com/containerd/containerd/content/local"
	controlapi "github.com/moby/buildkit/api/services/control"
	"github.com/moby/buildkit/client/llb"
	"github.com/moby/buildkit/client/ociindex"
	"github.com/moby/buildkit/exporter/containerimage/exptypes"
	"github.com/moby/buildkit/identity"
	"github.com/moby/buildkit/session"
	sessioncontent "github.com/moby/buildkit/session/content"
	"github.com/moby/buildkit/session/filesync"
	"github.com/moby/buildkit/session/grpchijack"
	"github.com/moby/buildkit/solver/pb"
	spb "github.com/moby/buildkit/sourcepolicy/pb"
	"github.com/moby/buildkit/util/bklog"
	"github.com/moby/buildkit/util/entitlements"
	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
	"github.com/pkg/errors"
	"github.com/tonistiigi/fsutil"
	fstypes "github.com/tonistiigi/fsutil/types"
	"go.opentelemetry.io/otel/trace"
	"golang.org/x/sync/errgroup"
)

type SolveOpt struct {
	Exports               []ExportEntry
	LocalDirs             map[string]string
	OCIStores             map[string]content.Store
	SharedKey             string
	Frontend              string
	FrontendAttrs         map[string]string
	FrontendInputs        map[string]llb.State
	CacheExports          []CacheOptionsEntry
	CacheImports          []CacheOptionsEntry
	Session               []session.Attachable
	AllowedEntitlements   []entitlements.Entitlement
	SharedSession         *session.Session // TODO: refactor to better session syncing
	SessionPreInitialized bool             // TODO: refactor to better session syncing
	Internal              bool
	SourcePolicy          *spb.Policy
}

type ExportEntry struct {
	Type      string
	Attrs     map[string]string
	Output    func(map[string]string) (io.WriteCloser, error) // for ExporterOCI and ExporterDocker
	OutputDir string                                          // for ExporterLocal
}

type CacheOptionsEntry struct {
	Type  string
	Attrs map[string]string
}

// Solve calls Solve on the controller.
// def must be nil if (and only if) opt.Frontend is set.
func (c *Client) Solve(ctx context.Context, def *llb.Definition, opt SolveOpt, statusChan chan *SolveStatus) (*SolveResponse, error) {
	defer func() {
		if statusChan != nil {
			close(statusChan)
		}
	}()

	if opt.Frontend == "" && def == nil {
		return nil, errors.New("invalid empty definition")
	}
	if opt.Frontend != "" && def != nil {
		return nil, errors.Errorf("invalid definition for frontend %s", opt.Frontend)
	}

	return c.solve(ctx, def, nil, opt, statusChan)
}

type runGatewayCB func(ref string, s *session.Session, opts map[string]string) error

func (c *Client) solve(ctx context.Context, def *llb.Definition, runGateway runGatewayCB, opt SolveOpt, statusChan chan *SolveStatus) (*SolveResponse, error) {
	if def != nil && runGateway != nil {
		return nil, errors.New("invalid with def and cb")
	}

	syncedDirs, err := prepareSyncedDirs(def, opt.LocalDirs)
	if err != nil {
		return nil, err
	}

	ref := identity.NewID()
	eg, ctx := errgroup.WithContext(ctx)

	statusContext, cancelStatus := context.WithCancel(context.Background())
	defer cancelStatus()

	if span := trace.SpanFromContext(ctx); span.SpanContext().IsValid() {
		statusContext = trace.ContextWithSpan(statusContext, span)
	}

	s := opt.SharedSession

	if s == nil {
		if opt.SessionPreInitialized {
			return nil, errors.Errorf("no session provided for preinitialized option")
		}
		s, err = session.NewSession(statusContext, defaultSessionName(), opt.SharedKey)
		if err != nil {
			return nil, errors.Wrap(err, "failed to create session")
		}
	}

	cacheOpt, err := parseCacheOptions(ctx, runGateway != nil, opt)
	if err != nil {
		return nil, err
	}

	var ex ExportEntry
	if len(opt.Exports) > 1 {
		return nil, errors.New("currently only single Exports can be specified")
	}
	if len(opt.Exports) == 1 {
		ex = opt.Exports[0]
	}

	storesToUpdate := []string{}

	if !opt.SessionPreInitialized {
		if len(syncedDirs) > 0 {
			s.Allow(filesync.NewFSSyncProvider(syncedDirs))
		}

		for _, a := range opt.Session {
			s.Allow(a)
		}

		contentStores := map[string]content.Store{}
		for key, store := range cacheOpt.contentStores {
			contentStores[key] = store
		}
		for key, store := range opt.OCIStores {
			key2 := "oci:" + key
			if _, ok := contentStores[key2]; ok {
				return nil, errors.Errorf("oci store key %q already exists", key)
			}
			contentStores[key2] = store
		}

		var supportFile bool
		var supportDir bool
		switch ex.Type {
		case ExporterLocal:
			supportDir = true
		case ExporterTar:
			supportFile = true
		case ExporterOCI, ExporterDocker:
			supportDir = ex.OutputDir != ""
			supportFile = ex.Output != nil
		}

		if supportFile && supportDir {
			return nil, errors.Errorf("both file and directory output is not support by %s exporter", ex.Type)
		}
		if !supportFile && ex.Output != nil {
			return nil, errors.Errorf("output file writer is not supported by %s exporter", ex.Type)
		}
		if !supportDir && ex.OutputDir != "" {
			return nil, errors.Errorf("output directory is not supported by %s exporter", ex.Type)
		}

		if supportFile {
			if ex.Output == nil {
				return nil, errors.Errorf("output file writer is required for %s exporter", ex.Type)
			}
			s.Allow(filesync.NewFSSyncTarget(ex.Output))
		}
		if supportDir {
			if ex.OutputDir == "" {
				return nil, errors.Errorf("output directory is required for %s exporter", ex.Type)
			}
			switch ex.Type {
			case ExporterOCI, ExporterDocker:
				if err := os.MkdirAll(ex.OutputDir, 0755); err != nil {
					return nil, err
				}
				cs, err := contentlocal.NewStore(ex.OutputDir)
				if err != nil {
					return nil, err
				}
				contentStores["export"] = cs
				storesToUpdate = append(storesToUpdate, ex.OutputDir)
			default:
				s.Allow(filesync.NewFSSyncTargetDir(ex.OutputDir))
			}
		}

		if len(contentStores) > 0 {
			s.Allow(sessioncontent.NewAttachable(contentStores))
		}

		eg.Go(func() error {
			sd := c.sessionDialer
			if sd == nil {
				sd = grpchijack.Dialer(c.ControlClient())
			}
			return s.Run(statusContext, sd)
		})
	}

	frontendAttrs := map[string]string{}
	for k, v := range opt.FrontendAttrs {
		frontendAttrs[k] = v
	}
	for k, v := range cacheOpt.frontendAttrs {
		frontendAttrs[k] = v
	}

	solveCtx, cancelSolve := context.WithCancel(ctx)
	var res *SolveResponse
	eg.Go(func() error {
		ctx := solveCtx
		defer cancelSolve()

		defer func() { // make sure the Status ends cleanly on build errors
			go func() {
				<-time.After(3 * time.Second)
				cancelStatus()
			}()
			if !opt.SessionPreInitialized {
				bklog.G(ctx).Debugf("stopping session")
				s.Close()
			}
		}()
		var pbd *pb.Definition
		if def != nil {
			pbd = def.ToPB()
		}

		frontendInputs := make(map[string]*pb.Definition)
		for key, st := range opt.FrontendInputs {
			def, err := st.Marshal(ctx)
			if err != nil {
				return err
			}
			frontendInputs[key] = def.ToPB()
		}

		resp, err := c.ControlClient().Solve(ctx, &controlapi.SolveRequest{
			Ref:            ref,
			Definition:     pbd,
			Exporter:       ex.Type,
			ExporterAttrs:  ex.Attrs,
			Session:        s.ID(),
			Frontend:       opt.Frontend,
			FrontendAttrs:  frontendAttrs,
			FrontendInputs: frontendInputs,
			Cache:          cacheOpt.options,
			Entitlements:   opt.AllowedEntitlements,
			Internal:       opt.Internal,
			SourcePolicy:   opt.SourcePolicy,
		})
		if err != nil {
			return errors.Wrap(err, "failed to solve")
		}
		res = &SolveResponse{
			ExporterResponse: resp.ExporterResponse,
		}
		return nil
	})

	if runGateway != nil {
		eg.Go(func() error {
			err := runGateway(ref, s, frontendAttrs)
			if err == nil {
				return nil
			}

			// If the callback failed then the main
			// `Solve` (called above) should error as
			// well. However as a fallback we wait up to
			// 5s for that to happen before failing this
			// goroutine.
			select {
			case <-solveCtx.Done():
			case <-time.After(5 * time.Second):
				cancelSolve()
			}

			return err
		})
	}

	eg.Go(func() error {
		stream, err := c.ControlClient().Status(statusContext, &controlapi.StatusRequest{
			Ref: ref,
		})
		if err != nil {
			return errors.Wrap(err, "failed to get status")
		}
		for {
			resp, err := stream.Recv()
			if err != nil {
				if err == io.EOF {
					return nil
				}
				return errors.Wrap(err, "failed to receive status")
			}
			if statusChan != nil {
				statusChan <- NewSolveStatus(resp)
			}
		}
	})

	if err := eg.Wait(); err != nil {
		return nil, err
	}
	// Update index.json of exported cache content store
	// FIXME(AkihiroSuda): dedupe const definition of cache/remotecache.ExporterResponseManifestDesc = "cache.manifest"
	if manifestDescJSON := res.ExporterResponse["cache.manifest"]; manifestDescJSON != "" {
		var manifestDesc ocispecs.Descriptor
		if err = json.Unmarshal([]byte(manifestDescJSON), &manifestDesc); err != nil {
			return nil, err
		}
		for storePath, tag := range cacheOpt.storesToUpdate {
			idx := ociindex.NewStoreIndex(storePath)
			if err := idx.Put(tag, manifestDesc); err != nil {
				return nil, err
			}
		}
	}
	if manifestDescDt := res.ExporterResponse[exptypes.ExporterImageDescriptorKey]; manifestDescDt != "" {
		manifestDescDt, err := base64.StdEncoding.DecodeString(manifestDescDt)
		if err != nil {
			return nil, err
		}
		var manifestDesc ocispecs.Descriptor
		if err = json.Unmarshal([]byte(manifestDescDt), &manifestDesc); err != nil {
			return nil, err
		}
		for _, storePath := range storesToUpdate {
			tag := "latest"
			if t, ok := res.ExporterResponse["image.name"]; ok {
				tag = t
			}
			idx := ociindex.NewStoreIndex(storePath)
			if err := idx.Put(tag, manifestDesc); err != nil {
				return nil, err
			}
		}
	}
	return res, nil
}

func prepareSyncedDirs(def *llb.Definition, localDirs map[string]string) (filesync.StaticDirSource, error) {
	for _, d := range localDirs {
		fi, err := os.Stat(d)
		if err != nil {
			return nil, errors.Wrapf(err, "could not find %s", d)
		}
		if !fi.IsDir() {
			return nil, errors.Errorf("%s not a directory", d)
		}
	}
	resetUIDAndGID := func(p string, st *fstypes.Stat) fsutil.MapResult {
		st.Uid = 0
		st.Gid = 0
		return fsutil.MapResultKeep
	}

	dirs := make(filesync.StaticDirSource, len(localDirs))
	if def == nil {
		for name, d := range localDirs {
			dirs[name] = filesync.SyncedDir{Dir: d, Map: resetUIDAndGID}
		}
	} else {
		for _, dt := range def.Def {
			var op pb.Op
			if err := (&op).Unmarshal(dt); err != nil {
				return nil, errors.Wrap(err, "failed to parse llb proto op")
			}
			if src := op.GetSource(); src != nil {
				if strings.HasPrefix(src.Identifier, "local://") {
					name := strings.TrimPrefix(src.Identifier, "local://")
					d, ok := localDirs[name]
					if !ok {
						return nil, errors.Errorf("local directory %s not enabled", name)
					}
					dirs[name] = filesync.SyncedDir{Dir: d, Map: resetUIDAndGID}
				}
			}
		}
	}
	return dirs, nil
}

func defaultSessionName() string {
	wd, err := os.Getwd()
	if err != nil {
		return "unknown"
	}
	return filepath.Base(wd)
}

type cacheOptions struct {
	options        controlapi.CacheOptions
	contentStores  map[string]content.Store // key: ID of content store ("local:" + csDir)
	storesToUpdate map[string]string        // key: path to content store, value: tag
	frontendAttrs  map[string]string
}

func parseCacheOptions(ctx context.Context, isGateway bool, opt SolveOpt) (*cacheOptions, error) {
	var (
		cacheExports []*controlapi.CacheOptionsEntry
		cacheImports []*controlapi.CacheOptionsEntry
	)
	contentStores := make(map[string]content.Store)
	storesToUpdate := make(map[string]string)
	frontendAttrs := make(map[string]string)
	for _, ex := range opt.CacheExports {
		if ex.Type == "local" {
			csDir := ex.Attrs["dest"]
			if csDir == "" {
				return nil, errors.New("local cache exporter requires dest")
			}
			if err := os.MkdirAll(csDir, 0755); err != nil {
				return nil, err
			}
			cs, err := contentlocal.NewStore(csDir)
			if err != nil {
				return nil, err
			}
			contentStores["local:"+csDir] = cs

			tag := "latest"
			if t, ok := ex.Attrs["tag"]; ok {
				tag = t
			}
			// TODO(AkihiroSuda): support custom index JSON path and tag
			storesToUpdate[csDir] = tag
		}
		if ex.Type == "registry" {
			regRef := ex.Attrs["ref"]
			if regRef == "" {
				return nil, errors.New("registry cache exporter requires ref")
			}
		}
		cacheExports = append(cacheExports, &controlapi.CacheOptionsEntry{
			Type:  ex.Type,
			Attrs: ex.Attrs,
		})
	}
	for _, im := range opt.CacheImports {
		if im.Type == "local" {
			csDir := im.Attrs["src"]
			if csDir == "" {
				return nil, errors.New("local cache importer requires src")
			}
			cs, err := contentlocal.NewStore(csDir)
			if err != nil {
				bklog.G(ctx).Warning("local cache import at " + csDir + " not found due to err: " + err.Error())
				continue
			}
			// if digest is not specified, attempt to load from tag
			if im.Attrs["digest"] == "" {
				tag := "latest"
				if t, ok := im.Attrs["tag"]; ok {
					tag = t
				}

				idx := ociindex.NewStoreIndex(csDir)
				desc, err := idx.Get(tag)
				if err != nil {
					bklog.G(ctx).Warning("local cache import at " + csDir + " not found due to err: " + err.Error())
					continue
				}
				if desc != nil {
					im.Attrs["digest"] = desc.Digest.String()
				}
			}
			if im.Attrs["digest"] == "" {
				return nil, errors.New("local cache importer requires either explicit digest, \"latest\" tag or custom tag on index.json")
			}
			contentStores["local:"+csDir] = cs
		}
		if im.Type == "registry" {
			regRef := im.Attrs["ref"]
			if regRef == "" {
				return nil, errors.New("registry cache importer requires ref")
			}
		}
		cacheImports = append(cacheImports, &controlapi.CacheOptionsEntry{
			Type:  im.Type,
			Attrs: im.Attrs,
		})
	}
	if opt.Frontend != "" || isGateway {
		if len(cacheImports) > 0 {
			s, err := json.Marshal(cacheImports)
			if err != nil {
				return nil, err
			}
			frontendAttrs["cache-imports"] = string(s)
		}
	}
	res := cacheOptions{
		options: controlapi.CacheOptions{
			Exports: cacheExports,
			Imports: cacheImports,
		},
		contentStores:  contentStores,
		storesToUpdate: storesToUpdate,
		frontendAttrs:  frontendAttrs,
	}
	return &res, nil
}
