package command

import (
	"errors"
	"fmt"
	"log"
	"os"
	"strings"

	"github.com/hashicorp/hcl2/hcl"
	"github.com/hashicorp/hcl2/hcl/hclsyntax"

	"github.com/hashicorp/terraform/addrs"
	"github.com/hashicorp/terraform/backend"
	"github.com/hashicorp/terraform/configs"
	"github.com/hashicorp/terraform/terraform"
	"github.com/hashicorp/terraform/tfdiags"
)

// ImportCommand is a cli.Command implementation that imports resources
// into the Terraform state.
type ImportCommand struct {
	Meta
}

func (c *ImportCommand) Run(args []string) int {
	// Get the pwd since its our default -config flag value
	pwd, err := os.Getwd()
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error getting pwd: %s", err))
		return 1
	}

	var configPath string
	args, err = c.Meta.process(args, true)
	if err != nil {
		return 1
	}

	cmdFlags := c.Meta.flagSet("import")
	cmdFlags.IntVar(&c.Meta.parallelism, "parallelism", 0, "parallelism")
	cmdFlags.StringVar(&c.Meta.statePath, "state", DefaultStateFilename, "path")
	cmdFlags.StringVar(&c.Meta.stateOutPath, "state-out", "", "path")
	cmdFlags.StringVar(&c.Meta.backupPath, "backup", "", "path")
	cmdFlags.StringVar(&configPath, "config", pwd, "path")
	cmdFlags.StringVar(&c.Meta.provider, "provider", "", "provider")
	cmdFlags.BoolVar(&c.Meta.stateLock, "lock", true, "lock state")
	cmdFlags.DurationVar(&c.Meta.stateLockTimeout, "lock-timeout", 0, "lock timeout")
	cmdFlags.BoolVar(&c.Meta.allowMissingConfig, "allow-missing-config", false, "allow missing config")
	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
	if err := cmdFlags.Parse(args); err != nil {
		return 1
	}

	args = cmdFlags.Args()
	if len(args) != 2 {
		c.Ui.Error("The import command expects two arguments.")
		cmdFlags.Usage()
		return 1
	}

	var diags tfdiags.Diagnostics

	// Parse the provided resource address.
	traversalSrc := []byte(args[0])
	traversal, travDiags := hclsyntax.ParseTraversalAbs(traversalSrc, "<import-address>", hcl.Pos{Line: 1, Column: 1})
	diags = diags.Append(travDiags)
	if travDiags.HasErrors() {
		c.registerSynthConfigSource("<import-address>", traversalSrc) // so we can include a source snippet
		c.showDiagnostics(diags)
		c.Ui.Info(importCommandInvalidAddressReference)
		return 1
	}
	addr, addrDiags := addrs.ParseAbsResourceInstance(traversal)
	diags = diags.Append(addrDiags)
	if addrDiags.HasErrors() {
		c.registerSynthConfigSource("<import-address>", traversalSrc) // so we can include a source snippet
		c.showDiagnostics(diags)
		c.Ui.Info(importCommandInvalidAddressReference)
		return 1
	}

	if addr.Resource.Resource.Mode != addrs.ManagedResourceMode {
		diags = diags.Append(errors.New("A managed resource address is required. Importing into a data resource is not allowed."))
		c.showDiagnostics(diags)
		return 1
	}

	if !c.dirIsConfigPath(configPath) {
		diags = diags.Append(&hcl.Diagnostic{
			Severity: hcl.DiagError,
			Summary:  "No Terraform configuration files",
			Detail: fmt.Sprintf(
				"The directory %s does not contain any Terraform configuration files (.tf or .tf.json). To specify a different configuration directory, use the -config=\"...\" command line option.",
				configPath,
			),
		})
		c.showDiagnostics(diags)
		return 1
	}

	// Load the full config, so we can verify that the target resource is
	// already configured.
	config, configDiags := c.loadConfig(configPath)
	diags = diags.Append(configDiags)
	if configDiags.HasErrors() {
		c.showDiagnostics(diags)
		return 1
	}

	// Verify that the given address points to something that exists in config.
	// This is to reduce the risk that a typo in the resource address will
	// import something that Terraform will want to immediately destroy on
	// the next plan, and generally acts as a reassurance of user intent.
	targetConfig := config.DescendentForInstance(addr.Module)
	if targetConfig == nil {
		modulePath := addr.Module.String()
		diags = diags.Append(&hcl.Diagnostic{
			Severity: hcl.DiagError,
			Summary:  "Import to non-existent module",
			Detail: fmt.Sprintf(
				"%s is not defined in the configuration. Please add configuration for this module before importing into it.",
				modulePath,
			),
		})
		c.showDiagnostics(diags)
		return 1
	}
	targetMod := targetConfig.Module
	rcs := targetMod.ManagedResources
	var rc *configs.Resource
	resourceRelAddr := addr.Resource.Resource
	for _, thisRc := range rcs {
		if resourceRelAddr.Type == thisRc.Type && resourceRelAddr.Name == thisRc.Name {
			rc = thisRc
			break
		}
	}
	if !c.Meta.allowMissingConfig && rc == nil {
		modulePath := addr.Module.String()
		if modulePath == "" {
			modulePath = "the root module"
		}

		c.showDiagnostics(diags)

		// This is not a diagnostic because currently our diagnostics printer
		// doesn't support having a code example in the detail, and there's
		// a code example in this message.
		// TODO: Improve the diagnostics printer so we can use it for this
		// message.
		c.Ui.Error(fmt.Sprintf(
			importCommandMissingResourceFmt,
			addr, modulePath, resourceRelAddr.Type, resourceRelAddr.Name,
		))
		return 1
	}

	// Also parse the user-provided provider address, if any.
	var providerAddr addrs.AbsProviderConfig
	if c.Meta.provider != "" {
		traversal, travDiags := hclsyntax.ParseTraversalAbs([]byte(c.Meta.provider), `-provider=...`, hcl.Pos{Line: 1, Column: 1})
		diags = diags.Append(travDiags)
		if travDiags.HasErrors() {
			c.showDiagnostics(diags)
			c.Ui.Info(importCommandInvalidAddressReference)
			return 1
		}
		relAddr, addrDiags := addrs.ParseProviderConfigCompact(traversal)
		diags = diags.Append(addrDiags)
		if addrDiags.HasErrors() {
			c.showDiagnostics(diags)
			return 1
		}
		providerAddr = relAddr.Absolute(addrs.RootModuleInstance)
	} else {
		// Use a default address inferred from the resource type.
		// We assume the same module as the resource address here, which
		// may get resolved to an inherited provider when we construct the
		// import graph inside ctx.Import, called below.
		providerAddr = resourceRelAddr.DefaultProviderConfig().Absolute(addr.Module)
	}

	// Check for user-supplied plugin path
	if c.pluginPath, err = c.loadPluginPath(); err != nil {
		c.Ui.Error(fmt.Sprintf("Error loading plugin path: %s", err))
		return 1
	}

	// Load the backend
	b, backendDiags := c.Backend(&BackendOpts{
		Config: config.Module.Backend,
	})
	diags = diags.Append(backendDiags)
	if backendDiags.HasErrors() {
		c.showDiagnostics(diags)
		return 1
	}

	// We require a backend.Local to build a context.
	// This isn't necessarily a "local.Local" backend, which provides local
	// operations, however that is the only current implementation. A
	// "local.Local" backend also doesn't necessarily provide local state, as
	// that may be delegated to a "remotestate.Backend".
	local, ok := b.(backend.Local)
	if !ok {
		c.Ui.Error(ErrUnsupportedLocalOp)
		return 1
	}

	// Build the operation
	opReq := c.Operation(b)
	opReq.ConfigDir = configPath
	opReq.ConfigLoader, err = c.initConfigLoader()
	if err != nil {
		diags = diags.Append(err)
		c.showDiagnostics(diags)
		return 1
	}

	// Get the context
	ctx, state, ctxDiags := local.Context(opReq)
	diags = diags.Append(ctxDiags)
	if ctxDiags.HasErrors() {
		c.showDiagnostics(diags)
		return 1
	}

	defer func() {
		err := opReq.StateLocker.Unlock(nil)
		if err != nil {
			c.Ui.Error(err.Error())
		}
	}()

	// Perform the import. Note that as you can see it is possible for this
	// API to import more than one resource at once. For now, we only allow
	// one while we stabilize this feature.
	newState, importDiags := ctx.Import(&terraform.ImportOpts{
		Targets: []*terraform.ImportTarget{
			&terraform.ImportTarget{
				Addr:         addr,
				ID:           args[1],
				ProviderAddr: providerAddr,
			},
		},
	})
	diags = diags.Append(importDiags)
	if diags.HasErrors() {
		c.showDiagnostics(diags)
		return 1
	}

	// Persist the final state
	log.Printf("[INFO] Writing state output to: %s", c.Meta.StateOutPath())
	if err := state.WriteState(newState); err != nil {
		c.Ui.Error(fmt.Sprintf("Error writing state file: %s", err))
		return 1
	}
	if err := state.PersistState(); err != nil {
		c.Ui.Error(fmt.Sprintf("Error writing state file: %s", err))
		return 1
	}

	c.Ui.Output(c.Colorize().Color("[reset][green]\n" + importCommandSuccessMsg))

	if c.Meta.allowMissingConfig && rc == nil {
		c.Ui.Output(c.Colorize().Color("[reset][yellow]\n" + importCommandAllowMissingResourceMsg))
	}

	c.showDiagnostics(diags)
	if diags.HasErrors() {
		return 1
	}

	return 0
}

func (c *ImportCommand) Help() string {
	helpText := `
Usage: terraform import [options] ADDR ID

  Import existing infrastructure into your Terraform state.

  This will find and import the specified resource into your Terraform
  state, allowing existing infrastructure to come under Terraform
  management without having to be initially created by Terraform.

  The ADDR specified is the address to import the resource to. Please
  see the documentation online for resource addresses. The ID is a
  resource-specific ID to identify that resource being imported. Please
  reference the documentation for the resource type you're importing to
  determine the ID syntax to use. It typically matches directly to the ID
  that the provider uses.

  The current implementation of Terraform import can only import resources
  into the state. It does not generate configuration. A future version of
  Terraform will also generate configuration.

  Because of this, prior to running terraform import it is necessary to write
  a resource configuration block for the resource manually, to which the
  imported object will be attached.

  This command will not modify your infrastructure, but it will make
  network requests to inspect parts of your infrastructure relevant to
  the resource being imported.

Options:

  -backup=path            Path to backup the existing state file before
                          modifying. Defaults to the "-state-out" path with
                          ".backup" extension. Set to "-" to disable backup.

  -config=path            Path to a directory of Terraform configuration files
                          to use to configure the provider. Defaults to pwd.
                          If no config files are present, they must be provided
                          via the input prompts or env vars.

  -allow-missing-config   Allow import when no resource configuration block exists.

  -input=true             Ask for input for variables if not directly set.

  -lock=true              Lock the state file when locking is supported.

  -lock-timeout=0s        Duration to retry a state lock.

  -no-color               If specified, output won't contain any color.

  -provider=provider      Specific provider to use for import. This is used for
                          specifying aliases, such as "aws.eu". Defaults to the
                          normal provider prefix of the resource being imported.

  -state=PATH             Path to the source state file. Defaults to the configured
                          backend, or "terraform.tfstate"

  -state-out=PATH         Path to the destination state file to write to. If this
                          isn't specified, the source state file will be used. This
                          can be a new or existing path.

  -var 'foo=bar'          Set a variable in the Terraform configuration. This
                          flag can be set multiple times. This is only useful
                          with the "-config" flag.

  -var-file=foo           Set variables in the Terraform configuration from
                          a file. If "terraform.tfvars" or any ".auto.tfvars"
                          files are present, they will be automatically loaded.


`
	return strings.TrimSpace(helpText)
}

func (c *ImportCommand) Synopsis() string {
	return "Import existing infrastructure into Terraform"
}

const importCommandInvalidAddressReference = `For information on valid syntax, see:
https://www.terraform.io/docs/internals/resource-addressing.html`

const importCommandMissingResourceFmt = `[reset][bold][red]Error:[reset][bold] resource address %q does not exist in the configuration.[reset]

Before importing this resource, please create its configuration in %s. For example:

resource %q %q {
  # (resource arguments)
}
`

const importCommandSuccessMsg = `Import successful!

The resources that were imported are shown above. These resources are now in
your Terraform state and will henceforth be managed by Terraform.
`

const importCommandAllowMissingResourceMsg = `Import does not generate resource configuration, you must create a resource
configuration block that matches the current or desired state manually.

If there is no matching resource configuration block for the imported
resource, Terraform will delete the resource on the next "terraform apply".
It is recommended that you run "terraform plan" to verify that the
configuration is correct and complete.
`