package run

import (
	"bytes"
	"context"
	"fmt"
	"path"
	"path/filepath"
	"time"

	"github.com/databricks/cli/bundle"
	"github.com/databricks/cli/bundle/config/resources"
	"github.com/databricks/cli/bundle/deploy"
	"github.com/databricks/cli/bundle/run/output"
	"github.com/databricks/cli/libs/cmdio"
	"github.com/databricks/cli/libs/filer"
	"github.com/databricks/databricks-sdk-go/service/apps"
	"github.com/spf13/cobra"

	"gopkg.in/yaml.v3"
)

func logProgress(ctx context.Context, msg string) {
	if msg == "" {
		return
	}
	cmdio.LogString(ctx, fmt.Sprintf("✓ %s", msg))
}

type appRunner struct {
	key

	bundle *bundle.Bundle
	app    *resources.App

	filerFactory deploy.FilerFactory
}

func (a *appRunner) Name() string {
	if a.app == nil {
		return ""
	}

	return a.app.Name
}

func isAppStopped(app *apps.App) bool {
	return app.ComputeStatus == nil ||
		(app.ComputeStatus.State == apps.ComputeStateStopped || app.ComputeStatus.State == apps.ComputeStateError)
}

func (a *appRunner) Run(ctx context.Context, opts *Options) (output.RunOutput, error) {
	app := a.app
	b := a.bundle
	if app == nil {
		return nil, fmt.Errorf("app is not defined")
	}

	logProgress(ctx, fmt.Sprintf("Getting the status of the app %s", app.Name))
	w := b.WorkspaceClient()

	// Check the status of the app first.
	createdApp, err := w.Apps.Get(ctx, apps.GetAppRequest{Name: app.Name})
	if err != nil {
		return nil, err
	}

	if createdApp.AppStatus != nil {
		logProgress(ctx, fmt.Sprintf("App is in %s state", createdApp.AppStatus.State))
	}

	if createdApp.ComputeStatus != nil {
		logProgress(ctx, fmt.Sprintf("App compute is in %s state", createdApp.ComputeStatus.State))
	}

	// There could be 2 reasons why the app is not running:
	// 1. The app is new and was never deployed yet.
	// 2. The app was stopped (compute not running).
	// We need to start the app only if the compute is not running.
	if isAppStopped(createdApp) {
		err := a.start(ctx)
		if err != nil {
			return nil, err
		}
	}

	// Deploy the app.
	err = a.deploy(ctx)
	if err != nil {
		return nil, err
	}

	cmdio.LogString(ctx, fmt.Sprintf("You can access the app at %s", createdApp.Url))
	return nil, nil
}

func (a *appRunner) start(ctx context.Context) error {
	app := a.app
	b := a.bundle
	w := b.WorkspaceClient()

	logProgress(ctx, fmt.Sprintf("Starting the app %s", app.Name))
	wait, err := w.Apps.Start(ctx, apps.StartAppRequest{Name: app.Name})
	if err != nil {
		return err
	}

	startedApp, err := wait.OnProgress(func(p *apps.App) {
		if p.AppStatus == nil {
			return
		}
		logProgress(ctx, "App is starting...")
	}).Get()

	if err != nil {
		return err
	}

	if startedApp.ActiveDeployment != nil &&
		startedApp.ActiveDeployment.Status.State == apps.AppDeploymentStateInProgress {
		logProgress(ctx, "Waiting for the active deployment to complete...")
		_, err = w.Apps.WaitGetDeploymentAppSucceeded(ctx, app.Name, startedApp.ActiveDeployment.DeploymentId, 20*time.Minute, nil)
		if err != nil {
			return err
		}
		logProgress(ctx, "Active deployment is completed!")
	}

	if startedApp.PendingDeployment != nil &&
		startedApp.PendingDeployment.Status.State == apps.AppDeploymentStateInProgress {
		logProgress(ctx, "Waiting for the pending deployment to complete...")
		_, err = w.Apps.WaitGetDeploymentAppSucceeded(ctx, app.Name, startedApp.PendingDeployment.DeploymentId, 20*time.Minute, nil)
		if err != nil {
			return err
		}
		logProgress(ctx, "Pending deployment is completed!")
	}

	logProgress(ctx, "App is started!")
	return nil
}

func (a *appRunner) deploy(ctx context.Context) error {
	app := a.app
	b := a.bundle
	w := b.WorkspaceClient()

	// If the app has a config, we need to deploy it first.
	// It means we need to write app.yml file with the content of the config field
	// to the remote source code path of the app.
	if app.Config != nil {
		appPath, err := filepath.Rel(b.Config.Workspace.FilePath, app.SourceCodePath)
		if err != nil {
			return fmt.Errorf("failed to get relative path of app source code path: %w", err)
		}

		buf, err := configToYaml(app)
		if err != nil {
			return err
		}

		// When the app is started, create a new app deployment and wait for it to complete.
		f, err := a.filerFactory(b)
		if err != nil {
			return err
		}

		err = f.Write(ctx, path.Join(appPath, "app.yml"), buf, filer.OverwriteIfExists)
		if err != nil {
			return fmt.Errorf("failed to write %s file: %w", path.Join(app.SourceCodePath, "app.yml"), err)
		}
	}

	wait, err := w.Apps.Deploy(ctx, apps.CreateAppDeploymentRequest{
		AppName: app.Name,
		AppDeployment: &apps.AppDeployment{
			Mode:           apps.AppDeploymentModeSnapshot,
			SourceCodePath: app.SourceCodePath,
		},
	})

	// If deploy returns an error, then there's an active deployment in progress, wait for it to complete.
	if err != nil {
		return err
	}

	_, err = wait.OnProgress(func(ad *apps.AppDeployment) {
		if ad.Status == nil {
			return
		}
		logProgress(ctx, ad.Status.Message)
	}).Get()

	if err != nil {
		return err
	}

	return nil
}

func (a *appRunner) Cancel(ctx context.Context) error {
	// We should cancel the app by stopping it.
	app := a.app
	b := a.bundle
	if app == nil {
		return fmt.Errorf("app is not defined")
	}

	w := b.WorkspaceClient()

	logProgress(ctx, fmt.Sprintf("Stopping app %s", app.Name))
	wait, err := w.Apps.Stop(ctx, apps.StopAppRequest{Name: app.Name})
	if err != nil {
		return err
	}

	_, err = wait.OnProgress(func(p *apps.App) {
		if p.AppStatus == nil {
			return
		}
		logProgress(ctx, p.AppStatus.Message)
	}).Get()

	logProgress(ctx, "App is stopped!")
	return err
}

func (a *appRunner) Restart(ctx context.Context, opts *Options) (output.RunOutput, error) {
	// We should restart the app by just running it again meaning a new app deployment will be done.
	return a.Run(ctx, opts)
}

func (a *appRunner) ParseArgs(args []string, opts *Options) error {
	if len(args) == 0 {
		return nil
	}

	return fmt.Errorf("received %d unexpected positional arguments", len(args))
}

func (a *appRunner) CompleteArgs(args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	return nil, cobra.ShellCompDirectiveNoFileComp
}

func configToYaml(app *resources.App) (*bytes.Buffer, error) {
	buf := bytes.NewBuffer(nil)
	enc := yaml.NewEncoder(buf)
	enc.SetIndent(2)

	err := enc.Encode(app.Config)
	defer enc.Close()

	if err != nil {
		return nil, fmt.Errorf("failed to encode app config to yaml: %w", err)
	}

	return buf, nil
}