package container

import (
	"archive/tar"
	"context"
	"encoding/hex"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"os"
	"path/filepath"
	"sync"
	"time"

	"connectrpc.com/connect"

	commonv1 "code.icb4dc0.de/buildr/api/generated/common/v1"
	remotev1 "code.icb4dc0.de/buildr/api/generated/remote/v1"
	"code.icb4dc0.de/buildr/common/protocol"

	"code.icb4dc0.de/buildr/buildr/modules/plugin"

	"code.icb4dc0.de/buildr/buildr/internal/rpc"

	"code.icb4dc0.de/buildr/buildr/internal/errs"
	"code.icb4dc0.de/buildr/buildr/modules/state"

	"github.com/klauspost/compress/s2"

	"code.icb4dc0.de/buildr/api/generated/remote/v1/rpcv1connect"

	"code.icb4dc0.de/buildr/buildr/internal/containers"
	"code.icb4dc0.de/buildr/buildr/internal/execution"
	"code.icb4dc0.de/buildr/buildr/internal/ioutils"
	"code.icb4dc0.de/buildr/buildr/internal/logging"
	"code.icb4dc0.de/buildr/buildr/modules"
)

const (
	defaultDirMode      os.FileMode = 0o755
	ownerExecutableMode os.FileMode = 0o700
)

type containerTask struct {
	stateStore     state.Store
	moduleWithMeta modules.ModuleWithMeta
	orchestrator   *containers.Orchestrator
	repo           *modules.Repository
	execution.TaskDependencies
	once sync.Once
}

func (c *containerTask) Execute(ctx context.Context, spec execution.Spec) (err error) {
	c.once.Do(func() {
		err = c.doExecute(ctx, spec)
	})

	return err
}

//nolint:funlen,gocognit,gocyclo // doesn't make sense to split it
func (c *containerTask) doExecute(ctx context.Context, spec execution.Spec) (err error) {
	if err := c.TaskDependencies.Execute(ctx, spec); err != nil {
		return err
	}

	if outDir := c.moduleWithMeta.OutDir(); outDir != "" {
		if err := os.MkdirAll(c.moduleWithMeta.OutDir(), defaultDirMode); err != nil {
			return err
		}
	}

	logger := slog.
		Default().
		With(
			slog.String("module_name", c.moduleWithMeta.Name()),
			slog.String("module_type", modules.CategoryName(c.moduleWithMeta.Category())),
		)

	if c.moduleWithMeta.ShouldSkip() {
		logger.Info("Skipping execution as requested")
		return nil
	}

	extraBinaries := make([]string, 0, len(c.TaskDependencies))

	for _, depid := range c.moduleWithMeta.Dependencies() {
		depMod := c.repo.ModuleByID(depid)
		if depMod == nil {
			continue
		}
		if binNamer, ok := depMod.Unwrap().(modules.BinaryNamer); ok {
			if extraBin, err := binNamer.BinaryName(ctx); err == nil && extraBin != "" {
				extraBinaries = append(extraBinaries, extraBin)
			}
		}
	}

	outputSink, err := logging.NewTaskOutputSink(
		spec.LogsDirectory,
		spec.LogToStdErr,
		modules.LogFileNameFormatter(c.moduleWithMeta),
	)
	if err != nil {
		return err
	}

	defer func() {
		err = errors.Join(err, outputSink.Close())
	}()

	inputMappings := c.moduleWithMeta.InputMappings()

	if len(inputMappings) == 0 {
		inputMappings[spec.RepoRoot] = "."
	}

	containerSpec := c.moduleWithMeta.ContainerSpec()
	buildrContainerSpec := containers.BuildRContainerSpec{
		ID:            c.moduleWithMeta.ID(),
		ModuleName:    c.moduleWithMeta.Name(),
		Image:         containerSpec.Image,
		User:          containerSpec.User,
		Privileged:    containerSpec.Privileged,
		RepoRoot:      spec.RepoRoot,
		Content:       inputMappings,
		BinariesDir:   spec.BinariesDirectory,
		ExtraBinaries: extraBinaries,
		Mounts:        containerSpec.Mounts(),
	}

	logger.Debug("Preparing container")
	con, baseURL, err := c.orchestrator.BuildRContainer(ctx, &buildrContainerSpec)
	if err != nil {
		return fmt.Errorf("failed to create container for task %s/%s: %w", c.moduleWithMeta.Type(), c.moduleWithMeta.Name(), err)
	}

	client := rpc.NewH2cHTTPClient()
	moduleReference := &commonv1.ModuleReference{
		ModuleCategory: c.moduleWithMeta.Category(),
		ModuleType:     c.moduleWithMeta.Type(),
	}

	if pluginModule, ok := c.moduleWithMeta.Unwrap().(plugin.Module); ok {
		payload, err := pluginModule.PluginPayload.Bytes()
		if err != nil {
			return err
		}
		pluginMgrClient := rpcv1connect.NewPluginManagerServiceClient(client, baseURL)
		registerPluginRequest := &remotev1.RegisterPluginModuleRequest{
			ModuleRef:     moduleReference,
			PluginPayload: payload,
		}
		if _, err := pluginMgrClient.RegisterPluginModule(ctx, connect.NewRequest(registerPluginRequest)); err != nil {
			return err
		}
	}

	executorClient := rpcv1connect.NewExecutorServiceClient(client, baseURL)

	logger.Debug("Start remote task execution")
	streamClient := executorClient.ExecuteStream(ctx)

	defer func() {
		err = errors.Join(err, streamClient.CloseRequest())
	}()

	rawModule, err := protocol.Marshal(c.moduleWithMeta.Unwrap())
	if err != nil {
		return fmt.Errorf("failed to marshal task spec as JSON: %w", err)
	}

	rawModule.Category = c.moduleWithMeta.Category()

	startTaskReq := &remotev1.ExecutionClientMessage{
		Envelope: &remotev1.ExecutionClientMessage_StartTask{
			StartTask: &remotev1.StartTaskRequest{
				Buildr: &remotev1.Buildr{
					Repo: &remotev1.Buildr_Repo{
						Root: fmt.Sprintf("/work/%s", c.moduleWithMeta.ID()),
					},
				},
				Reference: &remotev1.TaskReference{
					Id:     c.moduleWithMeta.ID(),
					Name:   c.moduleWithMeta.Name(),
					Module: moduleReference,
				},
				Spec: rawModule,
			},
		},
	}

	err = streamClient.Send(startTaskReq)
	if err != nil {
		return fmt.Errorf("failed to send start task request: %w", err)
	}

	for {
		ev, err := streamClient.Receive()
		if err != nil {
			return fmt.Errorf("failed to receive remote executor event: %w", err)
		}

		switch msg := ev.GetEnvelope().(type) {
		case *remotev1.ExecutionServerMessage_TaskLog:
			c.handleTaskLog(ctx, msg.TaskLog, logger)
		case *remotev1.ExecutionServerMessage_TaskOutput:
			logger.Debug("Handle task output")
			if err = c.handleTaskOutput(outputSink, msg.TaskOutput); err != nil {
				logger.Error("Failed to process task output", slog.String("err", err.Error()))
			}
		case *remotev1.ExecutionServerMessage_TaskResult:
			logger.Debug("Received task result")
			if errMsg := msg.TaskResult.Error; errMsg != "" {
				return fmt.Errorf("failed to execute task: %s", msg.TaskResult.Error)
			}

			if msg.TaskResult.ModifiedFilesArchivePath != "" {
				outDir := c.moduleWithMeta.OutDir()
				if c.moduleWithMeta.Category() == modules.CategoryTool {
					outDir = spec.BinariesDirectory
				}
				if err = c.handleModifiedFiles(ctx, con, msg.TaskResult.ModifiedFilesArchivePath, outDir); err != nil {
					return fmt.Errorf("failed to fetch modified files from execution container: %w", err)
				}
			}

			return nil
		case *remotev1.ExecutionServerMessage_SetState:
			msgIDMeta, ok := ev.Meta.(*remotev1.ExecutionServerMessage_MessageId)
			if !ok {
				continue
			}
			result := &remotev1.ExecutionClientMessage_Error{
				Error: new(remotev1.Result),
			}
			respMsg := &remotev1.ExecutionClientMessage{
				Meta: &remotev1.ExecutionClientMessage_RepliesTo{
					RepliesTo: msgIDMeta.MessageId,
				},
				Envelope: result,
			}

			k := state.PlainKey(msg.SetState.Key)
			if err = c.stateStore.Set(ctx, k, msg.SetState.Data); err != nil {
				result.Error.Error = err.Error()
				logger.Error("Failed to set state", slog.String("err", err.Error()), slog.String("key", hex.EncodeToString(k.Bytes())))
			}

			if err = streamClient.Send(respMsg); err != nil {
				logger.Error("Failed to send set status response", errs.Attr(err))
			}
		case *remotev1.ExecutionServerMessage_GetState:
			k := state.PlainKey(msg.GetState.Key)
			msgIDMeta, ok := ev.Meta.(*remotev1.ExecutionServerMessage_MessageId)
			if !ok {
				continue
			}

			respMsg := &remotev1.ExecutionClientMessage{
				Meta: &remotev1.ExecutionClientMessage_RepliesTo{
					RepliesTo: msgIDMeta.MessageId,
				},
			}

			data, _, err := c.stateStore.Get(ctx, k)
			if err == nil {
				respMsg.Envelope = &remotev1.ExecutionClientMessage_GetState{
					GetState: &remotev1.GetStateResponse{
						Key:  msg.GetState.Key,
						Data: data,
					},
				}
			} else {
				respMsg.Envelope = &remotev1.ExecutionClientMessage_Error{
					Error: &remotev1.Result{
						Error: err.Error(),
					},
				}
			}

			if err = streamClient.Send(respMsg); err != nil {
				logger.Error("Failed to send get status response", errs.Attr(err))
			}
		}
	}
}

func (c *containerTask) handleTaskOutput(sink logging.TaskOutputSink, req *remotev1.TaskOutput) (err error) {
	//nolint:exhaustive // not necessary here
	switch req.Source {
	case remotev1.TaskOutputSource_TASK_OUTPUT_SOURCE_STDOUT:
		writer := sink.StdOut()
		_, err = writer.Write(req.Payload)
		if syncer, ok := writer.(interface{ Sync() error }); ok {
			err = errors.Join(err, syncer.Sync())
		}
	case remotev1.TaskOutputSource_TASK_OUTPUT_SOURCE_STDERR:
		writer := sink.StdErr()
		_, err = writer.Write(req.Payload)
		if syncer, ok := writer.(interface{ Sync() error }); ok {
			err = errors.Join(err, syncer.Sync())
		}
	}

	return err
}

func (c *containerTask) handleTaskLog(ctx context.Context, taskLog *remotev1.TaskLog, logger *slog.Logger) {
	handler := logger.Handler()
	level := slog.Level(taskLog.Level)
	if !handler.Enabled(ctx, level) {
		return
	}

	rec := slog.NewRecord(time.UnixMicro(taskLog.Time), level, taskLog.Message, 0)
	for i := range taskLog.Attributes {
		attr := taskLog.Attributes[i]
		rec.AddAttrs(slog.String(attr.GetKey(), attr.GetValue()))
	}
	_ = logger.Handler().Handle(ctx, rec)
}

func (c *containerTask) handleModifiedFiles(ctx context.Context, con containers.Container, modifiedFilesPath, outDir string) error {
	return con.CopyFileFromContainer(ctx, modifiedFilesPath, func(_ *tar.Header, reader io.Reader) (err error) {
		deflateReader := s2.NewReader(reader)
		tarReader := tar.NewReader(deflateReader)

		var header *tar.Header
		for header, err = tarReader.Next(); err == nil; header, err = tarReader.Next() {
			if header.Typeflag == tar.TypeDir {
				if err := os.MkdirAll(filepath.Join(outDir, header.Name), os.FileMode(header.Mode)|ownerExecutableMode); err != nil {
					return err
				}
				continue
			}

			if header.Typeflag != tar.TypeReg {
				continue
			}

			var outFile *os.File
			outFile, err = os.OpenFile(filepath.Join(outDir, header.Name), os.O_RDWR|os.O_CREATE|os.O_TRUNC, os.FileMode(header.Mode))
			if err != nil {
				return err
			}

			_, err = ioutils.CopyWithPooledBuffer(outFile, tarReader)
			if err := errors.Join(err, outFile.Close()); err != nil {
				return err
			}
		}

		if errors.Is(err, io.EOF) {
			return nil
		}

		return err
	})
}