// Package remotestate contains code for configuring remote state storage.
package remotestate

import (
	"context"
	"errors"
	"fmt"
	"os"

	"github.com/gruntwork-io/terragrunt/internal/hclhelper"
	"github.com/gruntwork-io/terragrunt/internal/remotestate/backend"
	"github.com/gruntwork-io/terragrunt/internal/remotestate/backend/azurerm"
	"github.com/gruntwork-io/terragrunt/internal/remotestate/backend/gcs"
	"github.com/gruntwork-io/terragrunt/internal/remotestate/backend/s3"
	"github.com/gruntwork-io/terragrunt/internal/tf"
	"github.com/gruntwork-io/terragrunt/internal/vexec"
	"github.com/gruntwork-io/terragrunt/pkg/log"
)

var backends = backend.Backends{
	s3.NewBackend(),
	gcs.NewBackend(),
	azurerm.NewBackend(),
}

// Options contains the subset of configuration needed by RemoteState operations.
type Options struct {
	TFRunOpts *tf.TFOptions
	backend.Options
	DisableBucketUpdate bool
}

// RemoteState is the configuration for Terraform remote state.
type RemoteState struct {
	*Config `mapstructure:",squash"`
	backend backend.Backend
}

// New creates a new `RemoteState` instance. config may be nil when the
// caller (config.convertToTerragruntConfig) doesn't parse a remote_state
// block, e.g. a root.hcl that only declares locals — callers used to hit
// a nil pointer dereference at config.BackendName here and crash.
func New(config *Config) *RemoteState {
	if config == nil {
		return &RemoteState{
			Config:  &Config{},
			backend: backend.NewCommonBackend(""),
		}
	}

	remote := &RemoteState{
		Config:  config,
		backend: backend.NewCommonBackend(config.BackendName),
	}

	if backend := backends.Get(config.BackendName); backend != nil {
		remote.backend = backend
	}

	return remote
}

// String implements `fmt.Stringer` interface.
func (remote *RemoteState) String() string {
	return remote.Config.String()
}

func (remote *RemoteState) IsVersionControlEnabled(ctx context.Context, l log.Logger, opts *Options) (bool, error) {
	l.Debugf("Checking if version control is enabled for the %s backend", remote.BackendName)

	return remote.backend.IsVersionControlEnabled(ctx, l, remote.BackendConfig, &opts.Options)
}

// Delete deletes the remote state.
func (remote *RemoteState) Delete(ctx context.Context, l log.Logger, opts *Options) error {
	l.Debugf("Deleting remote state for the %s backend", remote.BackendName)

	return remote.backend.Delete(ctx, l, remote.BackendConfig, &opts.Options)
}

// DeleteBucket deletes the entire bucket.
func (remote *RemoteState) DeleteBucket(ctx context.Context, l log.Logger, opts *Options) error {
	l.Debugf("Deleting the entire bucket for the %s backend", remote.BackendName)

	return remote.backend.DeleteBucket(ctx, l, remote.BackendConfig, &opts.Options)
}

// Bootstrap performs any actions necessary to bootstrap remote state before it's used for storage. For example, if you're
// using S3 or GCS for remote state storage, this may create the bucket if it doesn't exist already.
func (remote *RemoteState) Bootstrap(ctx context.Context, l log.Logger, opts *Options) error {
	l.Debugf("Bootstrapping remote state for the %s backend", remote.BackendName)

	return remote.backend.Bootstrap(ctx, l, remote.BackendConfig, &opts.Options)
}

// Migrate determines where the remote state resources exist for source backend config and migrate them to dest backend config.
func (remote *RemoteState) Migrate(ctx context.Context, l log.Logger, exec vexec.Exec, opts, dstOpts *Options, dstRemote *RemoteState) error {
	l.Debugf("Migrate remote state for the %s backend", remote.BackendName)

	if remote.BackendName == dstRemote.BackendName {
		return remote.backend.Migrate(ctx, l, remote.BackendConfig, dstRemote.BackendConfig, &opts.Options)
	}

	stateFile, err := remote.pullState(ctx, l, exec, opts.TFRunOpts)
	if err != nil {
		return err
	}

	defer func() {
		if err := os.Remove(stateFile); err != nil && !errors.Is(err, os.ErrNotExist) {
			l.Warnf("Failed to remove temporary state file %s: %v", stateFile, err)
		}
	}()

	return dstRemote.pushState(ctx, l, exec, dstOpts.TFRunOpts, stateFile)
}

// NeedsBootstrap returns true if remote state needs to be configured. This will be the case when:
//
// 1. Remote state auto-initialization has been disabled.
// 2. Remote state has not already been configured.
// 3. Remote state has been configured, but with a different configuration.
// 4. The remote state bootstrapper for this backend type, if there is one, says bootstrap is necessary.
func (remote *RemoteState) NeedsBootstrap(ctx context.Context, l log.Logger, opts *Options) (bool, error) {
	if opts.DisableBucketUpdate {
		l.Debug("Skipping remote state bootstrap")
		return false, nil
	}

	if remote.DisableInit {
		return false, nil
	}

	// The specific backend type will check if bootstrap is necessary.
	l.Debugf("Checking if remote state bootstrap is necessary for the %s backend", remote.BackendName)

	return remote.backend.NeedsBootstrap(ctx, l, remote.BackendConfig, &opts.Options)
}

// GetTFInitArgs converts the RemoteState config into the format used by the `tofu init` command.
func (remote *RemoteState) GetTFInitArgs() []string {
	if remote.Generate != nil {
		// When in generate mode, we don't need to use `-backend-config` to initialize the remote state backend.
		return []string{}
	}

	config := remote.backend.GetTFInitArgs(remote.BackendConfig)

	var backendConfigArgs = make([]string, 0, len(config))

	for key, value := range config {
		var serialized string

		switch v := value.(type) {
		case string:
			serialized = v
		case map[string]any:
			serialized = hclhelper.WrapMapToSingleLineHcl(v)
		case []any:
			serialized = hclhelper.WrapListToSingleLineHcl(v)
		default:
			serialized = fmt.Sprintf("%v", value)
		}

		arg := fmt.Sprintf("-backend-config=%s=%s", key, serialized)
		backendConfigArgs = append(backendConfigArgs, arg)
	}

	return backendConfigArgs
}

// GenerateOpenTofuCode generates the OpenTofu/Terraform code for configuring remote state backend.
func (remote *RemoteState) GenerateOpenTofuCode(l log.Logger, workingDir string) error {
	backendConfig := remote.backend.GetTFInitArgs(remote.BackendConfig)

	return remote.Config.GenerateOpenTofuCode(l, workingDir, backendConfig)
}

func (remote *RemoteState) pullState(ctx context.Context, l log.Logger, exec vexec.Exec, tfOpts *tf.TFOptions) (string, error) {
	l.Debugf("Pulling state from %s backend", remote.BackendName)

	args := []string{tf.CommandNameState, tf.CommandNamePull}

	output, err := tf.RunCommandWithOutput(ctx, l, exec, tfOpts, args...)
	if err != nil {
		return "", err
	}

	l.Debugf("Creating temporary state file for migration")

	file, err := os.CreateTemp("", "*.tfstate")
	if err != nil {
		return "", err
	}

	defer func() {
		file.Close() // nolint: errcheck
	}()

	if _, err := file.Write(output.Stdout.Bytes()); err != nil {
		return file.Name(), err
	}

	return file.Name(), nil
}

func (remote *RemoteState) pushState(ctx context.Context, l log.Logger, exec vexec.Exec, tfOpts *tf.TFOptions, stateFile string) error {
	l.Debugf("Pushing state to %s backend", remote.BackendName)

	args := []string{tf.CommandNameState, tf.CommandNamePush, stateFile}

	return tf.RunCommand(ctx, l, exec, tfOpts, args...)
}
