package deploy

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"path/filepath"
	"strings"
	"time"

	"github.com/databricks/bricks/project"
	"github.com/databricks/databricks-sdk-go/databricks/client"
	"github.com/databricks/databricks-sdk-go/service/workspace"
)

// TODO: create a mutex for dbfs too
type Mutex interface {
	Lock(ctx context.Context) error
	Unlock(ctx context.Context) error
}

type DeployMutex struct {
	User string
	// Remove if we do not need this and its enoguh to assert that AcquireLock did not return an error
	AcquisitionTime time.Time
	// TODO: Add a timestamp demostrating the time of lock acquisition
	IsForced    bool
	ProjectRoot string
}

// TODO: Consider makeing aquire lock a blocking operation with a timeout. Incase of a race conflict, all lower priority
// lock claims would delete themselves and still one person would end up with the lock

// TODO: Lets keep a history of all the deployments made.
// 1. When waiting for lock, we can also show that from whom are we waiting to gain a lock from and when they accesses the lock
// 2. For force, delete all the other locks and
func (mu *DeployMutex) Lock(ctx context.Context) error {
	prj := project.Get(ctx)
	wsc := prj.WorkspacesClient()
	lockFilePath := filepath.Join(mu.ProjectRoot, ".bundle/deploy.lock")

	// Do I need to dereference this pointer to marshal ?
	mu.AcquisitionTime = time.Now()
	mutexMetadata, err := json.Marshal(*mu)
	if err != nil {
		return err
	}
	mutexMetadataReader := bytes.NewReader(mutexMetadata)

	// create .bundle dir in remote project root
	err = wsc.Workspace.MkdirsByPath(ctx, filepath.Dir(lockFilePath))
	if err != nil {
		return fmt.Errorf("could not mkdir to put file: %s", err)
	}

	// Try to create the lock file. If we get an error, that means the lock
	// file already exists
	apiClient, err := client.New(wsc.Config)
	if err != nil {
		return err
	}
	importApiPath := fmt.Sprintf(
		"/api/2.0/workspace-files/import-file/%s?overwrite=false",
		strings.TrimLeft(lockFilePath, "/"))
	err = apiClient.Post(ctx, importApiPath, mutexMetadataReader, nil)

	if err != nil && strings.Contains(err.Error(), fmt.Sprintf("%s already exists", lockFilePath)) {
		expectApiPath := fmt.Sprintf(
			"/api/2.0/workspace-files/%s",
			strings.TrimLeft(lockFilePath, "/"))

		var res interface{}

		err = apiClient.Get(ctx, expectApiPath, nil, &res)
		// TODO: handle the race condition when the file gets deleted before you can read
		// it.
		// NOTE: https://databricks.atlassian.net/browse/ES-510449
		// Do some error parsing maybe, add on previos error for more context and
		// add on suggestion for the user to retry deployment
		if err != nil {
			return err
		}
		lockJson, err := json.Marshal(res)
		if err != nil {
			return err
		}
		ownerMutex := DeployMutex{}
		err = json.Unmarshal(lockJson, &ownerMutex)
		if err != nil {
			return err
		}
		// TODO: add isForce to message here and convert timestamp to human readable format
		return fmt.Errorf("cannot deploy. %s has been deploying since %v. Use --force to forcibly deploy your bundle", ownerMutex.User, ownerMutex.AcquisitionTime)
	}
	return nil
}

func (mu *DeployMutex) Unlock(ctx context.Context) error {
	prj := project.Get(ctx)
	wsc := prj.WorkspacesClient()
	lockFilePath := filepath.Join(mu.ProjectRoot, ".bundle/deploy.lock")
	err := wsc.Workspace.Delete(ctx,
		workspace.Delete{
			Path:      lockFilePath,
			Recursive: false,
		},
	)
	return err
}