package terraform

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"golang.org/x/xerrors"

	"github.com/coder/coder/coderd/tracing"
	"github.com/coder/coder/provisionersdk"
	"github.com/coder/coder/provisionersdk/proto"
	"github.com/coder/terraform-provider-coder/provider"
)

// Provision executes `terraform apply` or `terraform plan` for dry runs.
func (s *server) Provision(stream proto.DRPCProvisioner_ProvisionStream) error {
	ctx, span := s.startTrace(stream.Context(), tracing.FuncName())
	defer span.End()

	request, err := stream.Recv()
	if err != nil {
		return err
	}
	if request.GetCancel() != nil {
		return nil
	}

	var (
		applyRequest = request.GetApply()
		planRequest  = request.GetPlan()
	)

	var config *proto.Provision_Config
	if applyRequest == nil && planRequest == nil {
		return nil
	} else if applyRequest != nil {
		config = applyRequest.Config
	} else if planRequest != nil {
		config = planRequest.Config
	}

	// Create a context for graceful cancellation bound to the stream
	// context. This ensures that we will perform graceful cancellation
	// even on connection loss.
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	// Create a separate context for forceful cancellation not tied to
	// the stream so that we can control when to terminate the process.
	killCtx, kill := context.WithCancel(context.Background())
	defer kill()

	// Ensure processes are eventually cleaned up on graceful
	// cancellation or disconnect.
	go func() {
		<-ctx.Done()

		// TODO(mafredri): We should track this provision request as
		// part of graceful server shutdown procedure. Waiting on a
		// process here should delay provisioner/coder shutdown.
		t := time.NewTimer(s.exitTimeout)
		defer t.Stop()
		select {
		case <-t.C:
			kill()
		case <-killCtx.Done():
		}
	}()

	go func() {
		for {
			request, err := stream.Recv()
			if err != nil {
				return
			}
			if request.GetCancel() == nil {
				// We only process cancellation requests here.
				continue
			}
			cancel()
			return
		}
	}()

	sink := streamLogSink{
		logger: s.logger.Named("execution_logs"),
		stream: stream,
	}

	e := s.executor(config.Directory)
	if err = e.checkMinVersion(ctx); err != nil {
		return err
	}
	logTerraformEnvVars(sink)

	statefilePath := filepath.Join(config.Directory, "terraform.tfstate")
	if len(config.State) > 0 {
		err = os.WriteFile(statefilePath, config.State, 0o600)
		if err != nil {
			return xerrors.Errorf("write statefile %q: %w", statefilePath, err)
		}
	}

	// If we're destroying, exit early if there's no state. This is necessary to
	// avoid any cases where a workspace is "locked out" of terraform due to
	// e.g. bad template param values and cannot be deleted. This is just for
	// contingency, in the future we will try harder to prevent workspaces being
	// broken this hard.
	if config.Metadata.WorkspaceTransition == proto.WorkspaceTransition_DESTROY && len(config.State) == 0 {
		_ = stream.Send(&proto.Provision_Response{
			Type: &proto.Provision_Response_Log{
				Log: &proto.Log{
					Level:  proto.LogLevel_INFO,
					Output: "The terraform state does not exist, there is nothing to do",
				},
			},
		})

		return stream.Send(&proto.Provision_Response{
			Type: &proto.Provision_Response_Complete{
				Complete: &proto.Provision_Complete{},
			},
		})
	}

	s.logger.Debug(ctx, "running initialization")
	err = e.init(ctx, killCtx, sink)
	if err != nil {
		if ctx.Err() != nil {
			return stream.Send(&proto.Provision_Response{
				Type: &proto.Provision_Response_Complete{
					Complete: &proto.Provision_Complete{
						Error: err.Error(),
					},
				},
			})
		}
		return xerrors.Errorf("initialize terraform: %w", err)
	}
	s.logger.Debug(ctx, "ran initialization")
	env, err := provisionEnv(config, request.GetPlan().GetRichParameterValues(), request.GetPlan().GetGitAuthProviders())
	if err != nil {
		return err
	}

	var resp *proto.Provision_Response
	if planRequest != nil {
		vars, err := planVars(planRequest)
		if err != nil {
			return err
		}

		resp, err = e.plan(
			ctx, killCtx, env, vars, sink,
			config.Metadata.WorkspaceTransition == proto.WorkspaceTransition_DESTROY,
		)
		if err != nil {
			if ctx.Err() != nil {
				return stream.Send(&proto.Provision_Response{
					Type: &proto.Provision_Response_Complete{
						Complete: &proto.Provision_Complete{
							Error: err.Error(),
						},
					},
				})
			}
			return xerrors.Errorf("plan terraform: %w", err)
		}
		return stream.Send(resp)
	}
	// Must be apply
	resp, err = e.apply(
		ctx, killCtx, applyRequest.Plan, env, sink,
	)
	if err != nil {
		errorMessage := err.Error()
		// Terraform can fail and apply and still need to store it's state.
		// In this case, we return Complete with an explicit error message.
		stateData, _ := os.ReadFile(statefilePath)
		return stream.Send(&proto.Provision_Response{
			Type: &proto.Provision_Response_Complete{
				Complete: &proto.Provision_Complete{
					State: stateData,
					Error: errorMessage,
				},
			},
		})
	}
	return stream.Send(resp)
}

func planVars(plan *proto.Provision_Plan) ([]string, error) {
	vars := []string{}
	for _, variable := range plan.VariableValues {
		vars = append(vars, fmt.Sprintf("%s=%s", variable.Name, variable.Value))
	}
	return vars, nil
}

func provisionEnv(config *proto.Provision_Config, richParams []*proto.RichParameterValue, gitAuth []*proto.GitAuthProvider) ([]string, error) {
	env := safeEnviron()
	env = append(env,
		"CODER_AGENT_URL="+config.Metadata.CoderUrl,
		"CODER_WORKSPACE_TRANSITION="+strings.ToLower(config.Metadata.WorkspaceTransition.String()),
		"CODER_WORKSPACE_NAME="+config.Metadata.WorkspaceName,
		"CODER_WORKSPACE_OWNER="+config.Metadata.WorkspaceOwner,
		"CODER_WORKSPACE_OWNER_EMAIL="+config.Metadata.WorkspaceOwnerEmail,
		"CODER_WORKSPACE_OWNER_OIDC_ACCESS_TOKEN="+config.Metadata.WorkspaceOwnerOidcAccessToken,
		"CODER_WORKSPACE_ID="+config.Metadata.WorkspaceId,
		"CODER_WORKSPACE_OWNER_ID="+config.Metadata.WorkspaceOwnerId,
		"CODER_WORKSPACE_OWNER_SESSION_TOKEN="+config.Metadata.WorkspaceOwnerSessionToken,
	)
	for key, value := range provisionersdk.AgentScriptEnv() {
		env = append(env, key+"="+value)
	}
	for _, param := range richParams {
		env = append(env, provider.ParameterEnvironmentVariable(param.Name)+"="+param.Value)
	}
	for _, gitAuth := range gitAuth {
		env = append(env, provider.GitAuthAccessTokenEnvironmentVariable(gitAuth.Id)+"="+gitAuth.AccessToken)
	}

	if config.ProvisionerLogLevel != "" {
		// TF_LOG=JSON enables all kind of logging: trace-debug-info-warn-error.
		// The idea behind using TF_LOG=JSON instead of TF_LOG=debug is ensuring the proper log format.
		env = append(env, "TF_LOG=JSON")
	}
	return env, nil
}

// tfEnvSafeToPrint is the set of terraform environment variables that we are quite sure won't contain secrets,
// and therefore it's ok to log their values
var tfEnvSafeToPrint = map[string]bool{
	"TF_LOG":                      true,
	"TF_LOG_PATH":                 true,
	"TF_INPUT":                    true,
	"TF_DATA_DIR":                 true,
	"TF_WORKSPACE":                true,
	"TF_IN_AUTOMATION":            true,
	"TF_REGISTRY_DISCOVERY_RETRY": true,
	"TF_REGISTRY_CLIENT_TIMEOUT":  true,
	"TF_CLI_CONFIG_FILE":          true,
	"TF_IGNORE":                   true,
}

func logTerraformEnvVars(sink logSink) {
	env := safeEnviron()
	for _, e := range env {
		if strings.HasPrefix(e, "TF_") {
			parts := strings.SplitN(e, "=", 2)
			if len(parts) != 2 {
				panic("safeEnviron() returned vars not in key=value form")
			}
			if !tfEnvSafeToPrint[parts[0]] {
				parts[1] = "<value redacted>"
			}
			sink.Log(&proto.Log{
				Level:  proto.LogLevel_WARN,
				Output: fmt.Sprintf("terraform environment variable: %s=%s", parts[0], parts[1]),
			})
		}
	}
}