package plugin

import (
	"context"
	"errors"
	"fmt"
	"runtime"
	"strings"
	"sync"

	"github.com/zclconf/go-cty/cty"

	plugin "github.com/hashicorp/go-plugin"
	"github.com/hashicorp/terraform/internal/logging"
	proto "github.com/hashicorp/terraform/internal/tfplugin5"
	"github.com/hashicorp/terraform/plugin/convert"
	"github.com/hashicorp/terraform/providers"
	"github.com/hashicorp/terraform/tfdiags"
	ctyjson "github.com/zclconf/go-cty/cty/json"
	"github.com/zclconf/go-cty/cty/msgpack"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

var logger = logging.HCLogger()

// GRPCProviderPlugin implements plugin.GRPCPlugin for the go-plugin package.
type GRPCProviderPlugin struct {
	plugin.Plugin
	GRPCProvider func() proto.ProviderServer
}

func (p *GRPCProviderPlugin) GRPCClient(ctx context.Context, broker *plugin.GRPCBroker, c *grpc.ClientConn) (interface{}, error) {
	return &GRPCProvider{
		client: proto.NewProviderClient(c),
		ctx:    ctx,
	}, nil
}

func (p *GRPCProviderPlugin) GRPCServer(broker *plugin.GRPCBroker, s *grpc.Server) error {
	proto.RegisterProviderServer(s, p.GRPCProvider())
	return nil
}

// GRPCProvider handles the client, or core side of the plugin rpc connection.
// The GRPCProvider methods are mostly a translation layer between the
// terraform provioders types and the grpc proto types, directly converting
// between the two.
type GRPCProvider struct {
	// PluginClient provides a reference to the plugin.Client which controls the plugin process.
	// This allows the GRPCProvider a way to shutdown the plugin process.
	PluginClient *plugin.Client

	// TestServer contains a grpc.Server to close when the GRPCProvider is being
	// used in an end to end test of a provider.
	TestServer *grpc.Server

	// Proto client use to make the grpc service calls.
	client proto.ProviderClient

	// this context is created by the plugin package, and is canceled when the
	// plugin process ends.
	ctx context.Context

	// schema stores the schema for this provider. This is used to properly
	// serialize the state for requests.
	mu      sync.Mutex
	schemas providers.GetSchemaResponse
}

// getSchema is used internally to get the saved provider schema.  The schema
// should have already been fetched from the provider, but we have to
// synchronize access to avoid being called concurrently with GetSchema.
func (p *GRPCProvider) getSchema() providers.GetSchemaResponse {
	p.mu.Lock()
	// unlock inline in case GetSchema needs to be called
	if p.schemas.Provider.Block != nil {
		p.mu.Unlock()
		return p.schemas
	}
	p.mu.Unlock()

	// the schema should have been fetched already, but give it another shot
	// just in case things are being called out of order. This may happen for
	// tests.
	schemas := p.GetSchema()
	if schemas.Diagnostics.HasErrors() {
		panic(schemas.Diagnostics.Err())
	}

	return schemas
}

// getResourceSchema is a helper to extract the schema for a resource, and
// panics if the schema is not available.
func (p *GRPCProvider) getResourceSchema(name string) providers.Schema {
	schema := p.getSchema()
	resSchema, ok := schema.ResourceTypes[name]
	if !ok {
		panic("unknown resource type " + name)
	}
	return resSchema
}

// gettDatasourceSchema is a helper to extract the schema for a datasource, and
// panics if that schema is not available.
func (p *GRPCProvider) getDatasourceSchema(name string) providers.Schema {
	schema := p.getSchema()
	dataSchema, ok := schema.DataSources[name]
	if !ok {
		panic("unknown data source " + name)
	}
	return dataSchema
}

// getProviderMetaSchema is a helper to extract the schema for the meta info
// defined for a provider,
func (p *GRPCProvider) getProviderMetaSchema() providers.Schema {
	schema := p.getSchema()
	return schema.ProviderMeta
}

func (p *GRPCProvider) GetSchema() (resp providers.GetSchemaResponse) {
	logger.Trace("GRPCProvider: GetSchema")
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.schemas.Provider.Block != nil {
		return p.schemas
	}

	resp.ResourceTypes = make(map[string]providers.Schema)
	resp.DataSources = make(map[string]providers.Schema)

	// Some providers may generate quite large schemas, and the internal default
	// grpc response size limit is 4MB. 64MB should cover most any use case, and
	// if we get providers nearing that we may want to consider a finer-grained
	// API to fetch individual resource schemas.
	// Note: this option is marked as EXPERIMENTAL in the grpc API.
	const maxRecvSize = 64 << 20
	protoResp, err := p.client.GetSchema(p.ctx, new(proto.GetProviderSchema_Request), grpc.MaxRecvMsgSizeCallOption{MaxRecvMsgSize: maxRecvSize})
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}

	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))

	if protoResp.Provider == nil {
		resp.Diagnostics = resp.Diagnostics.Append(errors.New("missing provider schema"))
		return resp
	}

	resp.Provider = convert.ProtoToProviderSchema(protoResp.Provider)
	if protoResp.ProviderMeta == nil {
		logger.Debug("No provider meta schema returned")
	} else {
		resp.ProviderMeta = convert.ProtoToProviderSchema(protoResp.ProviderMeta)
	}

	for name, res := range protoResp.ResourceSchemas {
		resp.ResourceTypes[name] = convert.ProtoToProviderSchema(res)
	}

	for name, data := range protoResp.DataSourceSchemas {
		resp.DataSources[name] = convert.ProtoToProviderSchema(data)
	}

	p.schemas = resp

	return resp
}

func (p *GRPCProvider) PrepareProviderConfig(r providers.PrepareProviderConfigRequest) (resp providers.PrepareProviderConfigResponse) {
	logger.Trace("GRPCProvider: PrepareProviderConfig")

	schema := p.getSchema()
	ty := schema.Provider.Block.ImpliedType()

	mp, err := msgpack.Marshal(r.Config, ty)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.PrepareProviderConfig_Request{
		Config: &proto.DynamicValue{Msgpack: mp},
	}

	protoResp, err := p.client.PrepareProviderConfig(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}

	config, err := decodeDynamicValue(protoResp.PreparedConfig, ty)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	resp.PreparedConfig = config

	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))
	return resp
}

func (p *GRPCProvider) ValidateResourceTypeConfig(r providers.ValidateResourceTypeConfigRequest) (resp providers.ValidateResourceTypeConfigResponse) {
	logger.Trace("GRPCProvider: ValidateResourceTypeConfig")
	resourceSchema := p.getResourceSchema(r.TypeName)

	mp, err := msgpack.Marshal(r.Config, resourceSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.ValidateResourceTypeConfig_Request{
		TypeName: r.TypeName,
		Config:   &proto.DynamicValue{Msgpack: mp},
	}

	protoResp, err := p.client.ValidateResourceTypeConfig(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}

	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))
	return resp
}

func (p *GRPCProvider) ValidateDataSourceConfig(r providers.ValidateDataSourceConfigRequest) (resp providers.ValidateDataSourceConfigResponse) {
	logger.Trace("GRPCProvider: ValidateDataSourceConfig")

	dataSchema := p.getDatasourceSchema(r.TypeName)

	mp, err := msgpack.Marshal(r.Config, dataSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.ValidateDataSourceConfig_Request{
		TypeName: r.TypeName,
		Config:   &proto.DynamicValue{Msgpack: mp},
	}

	protoResp, err := p.client.ValidateDataSourceConfig(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))
	return resp
}

func (p *GRPCProvider) UpgradeResourceState(r providers.UpgradeResourceStateRequest) (resp providers.UpgradeResourceStateResponse) {
	logger.Trace("GRPCProvider: UpgradeResourceState")

	resSchema := p.getResourceSchema(r.TypeName)

	protoReq := &proto.UpgradeResourceState_Request{
		TypeName: r.TypeName,
		Version:  int64(r.Version),
		RawState: &proto.RawState{
			Json:    r.RawStateJSON,
			Flatmap: r.RawStateFlatmap,
		},
	}

	protoResp, err := p.client.UpgradeResourceState(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))

	ty := resSchema.Block.ImpliedType()
	resp.UpgradedState = cty.NullVal(ty)
	if protoResp.UpgradedState == nil {
		return resp
	}

	state, err := decodeDynamicValue(protoResp.UpgradedState, ty)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	resp.UpgradedState = state

	return resp
}

func (p *GRPCProvider) Configure(r providers.ConfigureRequest) (resp providers.ConfigureResponse) {
	logger.Trace("GRPCProvider: Configure")

	schema := p.getSchema()

	var mp []byte

	// we don't have anything to marshal if there's no config
	mp, err := msgpack.Marshal(r.Config, schema.Provider.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.Configure_Request{
		TerraformVersion: r.TerraformVersion,
		Config: &proto.DynamicValue{
			Msgpack: mp,
		},
	}

	protoResp, err := p.client.Configure(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))
	return resp
}

func (p *GRPCProvider) Stop() error {
	logger.Trace("GRPCProvider: Stop")

	resp, err := p.client.Stop(p.ctx, new(proto.Stop_Request))
	if err != nil {
		return err
	}

	if resp.Error != "" {
		return errors.New(resp.Error)
	}
	return nil
}

func (p *GRPCProvider) ReadResource(r providers.ReadResourceRequest) (resp providers.ReadResourceResponse) {
	logger.Trace("GRPCProvider: ReadResource")

	resSchema := p.getResourceSchema(r.TypeName)
	metaSchema := p.getProviderMetaSchema()

	mp, err := msgpack.Marshal(r.PriorState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.ReadResource_Request{
		TypeName:     r.TypeName,
		CurrentState: &proto.DynamicValue{Msgpack: mp},
		Private:      r.Private,
	}

	if metaSchema.Block != nil {
		metaMP, err := msgpack.Marshal(r.ProviderMeta, metaSchema.Block.ImpliedType())
		if err != nil {
			resp.Diagnostics = resp.Diagnostics.Append(err)
			return resp
		}
		protoReq.ProviderMeta = &proto.DynamicValue{Msgpack: metaMP}
	}

	protoResp, err := p.client.ReadResource(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))

	state, err := decodeDynamicValue(protoResp.NewState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	resp.NewState = state
	resp.Private = protoResp.Private

	return resp
}

func (p *GRPCProvider) PlanResourceChange(r providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
	logger.Trace("GRPCProvider: PlanResourceChange")

	resSchema := p.getResourceSchema(r.TypeName)
	metaSchema := p.getProviderMetaSchema()

	priorMP, err := msgpack.Marshal(r.PriorState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	configMP, err := msgpack.Marshal(r.Config, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	propMP, err := msgpack.Marshal(r.ProposedNewState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.PlanResourceChange_Request{
		TypeName:         r.TypeName,
		PriorState:       &proto.DynamicValue{Msgpack: priorMP},
		Config:           &proto.DynamicValue{Msgpack: configMP},
		ProposedNewState: &proto.DynamicValue{Msgpack: propMP},
		PriorPrivate:     r.PriorPrivate,
	}

	if metaSchema.Block != nil {
		metaMP, err := msgpack.Marshal(r.ProviderMeta, metaSchema.Block.ImpliedType())
		if err != nil {
			resp.Diagnostics = resp.Diagnostics.Append(err)
			return resp
		}
		protoReq.ProviderMeta = &proto.DynamicValue{Msgpack: metaMP}
	}

	protoResp, err := p.client.PlanResourceChange(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))

	state, err := decodeDynamicValue(protoResp.PlannedState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	resp.PlannedState = state

	for _, p := range protoResp.RequiresReplace {
		resp.RequiresReplace = append(resp.RequiresReplace, convert.AttributePathToPath(p))
	}

	resp.PlannedPrivate = protoResp.PlannedPrivate

	resp.LegacyTypeSystem = protoResp.LegacyTypeSystem

	return resp
}

func (p *GRPCProvider) ApplyResourceChange(r providers.ApplyResourceChangeRequest) (resp providers.ApplyResourceChangeResponse) {
	logger.Trace("GRPCProvider: ApplyResourceChange")

	resSchema := p.getResourceSchema(r.TypeName)
	metaSchema := p.getProviderMetaSchema()

	priorMP, err := msgpack.Marshal(r.PriorState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	plannedMP, err := msgpack.Marshal(r.PlannedState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	configMP, err := msgpack.Marshal(r.Config, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.ApplyResourceChange_Request{
		TypeName:       r.TypeName,
		PriorState:     &proto.DynamicValue{Msgpack: priorMP},
		PlannedState:   &proto.DynamicValue{Msgpack: plannedMP},
		Config:         &proto.DynamicValue{Msgpack: configMP},
		PlannedPrivate: r.PlannedPrivate,
	}

	if metaSchema.Block != nil {
		metaMP, err := msgpack.Marshal(r.ProviderMeta, metaSchema.Block.ImpliedType())
		if err != nil {
			resp.Diagnostics = resp.Diagnostics.Append(err)
			return resp
		}
		protoReq.ProviderMeta = &proto.DynamicValue{Msgpack: metaMP}
	}

	protoResp, err := p.client.ApplyResourceChange(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))

	resp.Private = protoResp.Private

	state, err := decodeDynamicValue(protoResp.NewState, resSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	resp.NewState = state

	resp.LegacyTypeSystem = protoResp.LegacyTypeSystem

	return resp
}

func (p *GRPCProvider) ImportResourceState(r providers.ImportResourceStateRequest) (resp providers.ImportResourceStateResponse) {
	logger.Trace("GRPCProvider: ImportResourceState")

	protoReq := &proto.ImportResourceState_Request{
		TypeName: r.TypeName,
		Id:       r.ID,
	}

	protoResp, err := p.client.ImportResourceState(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))

	for _, imported := range protoResp.ImportedResources {
		resource := providers.ImportedResource{
			TypeName: imported.TypeName,
			Private:  imported.Private,
		}

		resSchema := p.getResourceSchema(resource.TypeName)
		state, err := decodeDynamicValue(imported.State, resSchema.Block.ImpliedType())
		if err != nil {
			resp.Diagnostics = resp.Diagnostics.Append(err)
			return resp
		}
		resource.State = state
		resp.ImportedResources = append(resp.ImportedResources, resource)
	}

	return resp
}

func (p *GRPCProvider) ReadDataSource(r providers.ReadDataSourceRequest) (resp providers.ReadDataSourceResponse) {
	logger.Trace("GRPCProvider: ReadDataSource")

	dataSchema := p.getDatasourceSchema(r.TypeName)
	metaSchema := p.getProviderMetaSchema()

	config, err := msgpack.Marshal(r.Config, dataSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}

	protoReq := &proto.ReadDataSource_Request{
		TypeName: r.TypeName,
		Config: &proto.DynamicValue{
			Msgpack: config,
		},
	}

	if metaSchema.Block != nil {
		metaMP, err := msgpack.Marshal(r.ProviderMeta, metaSchema.Block.ImpliedType())
		if err != nil {
			resp.Diagnostics = resp.Diagnostics.Append(err)
			return resp
		}
		protoReq.ProviderMeta = &proto.DynamicValue{Msgpack: metaMP}
	}

	protoResp, err := p.client.ReadDataSource(p.ctx, protoReq)
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(grpcErr(err))
		return resp
	}
	resp.Diagnostics = resp.Diagnostics.Append(convert.ProtoToDiagnostics(protoResp.Diagnostics))

	state, err := decodeDynamicValue(protoResp.State, dataSchema.Block.ImpliedType())
	if err != nil {
		resp.Diagnostics = resp.Diagnostics.Append(err)
		return resp
	}
	resp.State = state

	return resp
}

// closing the grpc connection is final, and terraform will call it at the end of every phase.
func (p *GRPCProvider) Close() error {
	logger.Trace("GRPCProvider: Close")

	// Make sure to stop the server if we're not running within go-plugin.
	if p.TestServer != nil {
		p.TestServer.Stop()
	}

	// Check this since it's not automatically inserted during plugin creation.
	// It's currently only inserted by the command package, because that is
	// where the factory is built and is the only point with access to the
	// plugin.Client.
	if p.PluginClient == nil {
		logger.Debug("provider has no plugin.Client")
		return nil
	}

	p.PluginClient.Kill()
	return nil
}

// Decode a DynamicValue from either the JSON or MsgPack encoding.
func decodeDynamicValue(v *proto.DynamicValue, ty cty.Type) (cty.Value, error) {
	// always return a valid value
	var err error
	res := cty.NullVal(ty)
	if v == nil {
		return res, nil
	}

	switch {
	case len(v.Msgpack) > 0:
		res, err = msgpack.Unmarshal(v.Msgpack, ty)
	case len(v.Json) > 0:
		res, err = ctyjson.Unmarshal(v.Json, ty)
	}
	return res, err
}

// grpcErr extracts some known error types and formats them into better
// representations for core. This must only be called from plugin methods.
// Since we don't use RPC status errors for the plugin protocol, these do not
// contain any useful details, and we can return some text that at least
// indicates the plugin call and possible error condition.
func grpcErr(err error) (diags tfdiags.Diagnostics) {
	if err == nil {
		return
	}

	// extract the method name from the caller.
	pc, _, _, ok := runtime.Caller(1)
	if !ok {
		return diags.Append(err)
	}

	f := runtime.FuncForPC(pc)
	requestName := f.Name()
	dot := strings.LastIndex(requestName, ".")
	if dot > 0 {
		requestName = requestName[dot+1:]
	}

	// Here we can at least correlate the error in the logs to a particular binary.
	logger.Error("GRPCProvider."+requestName, "error", err)

	// TODO: while this expands the error codes into somewhat better messages,
	// this still does not easily link the error to the an actual
	// user-recognizable provider. The GRPCProvider does not know its
	// configured name, and the errors are in a list of diagnostics, making it
	// hard for the the caller to annotate the returned errors.
	switch status.Code(err) {
	case codes.Unavailable:
		// This case is when the provider has stopped running for some reason,
		// and is usually the result of a crash.
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Error,
			"Provider did not respond",
			fmt.Sprintf("The provider encountered an error, and failed to respond to the %s call. "+
				"The provider logs may contain more details", requestName),
		))
	case codes.Canceled:
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Error,
			"Request cancelled",
			fmt.Sprintf("The %s request was cancelled.", requestName),
		))
	case codes.Unimplemented:
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Error,
			"Unsupported plugin method",
			fmt.Sprintf("The %s method is not supported by this provider", requestName),
		))
	default:
		diags = diags.Append(tfdiags.Sourceless(
			tfdiags.Error,
			"Provider error",
			fmt.Sprintf("The provider returned an unexpected error from %s: %v", requestName, err),
		))
	}
	return
}