package command

import (
	"fmt"
	"strings"

	"github.com/hashicorp/terraform/backend"
	"github.com/hashicorp/terraform/command/arguments"
	"github.com/hashicorp/terraform/command/views"
	"github.com/hashicorp/terraform/tfdiags"
)

// RefreshCommand is a cli.Command implementation that refreshes the state
// file.
type RefreshCommand struct {
	Meta
}

func (c *RefreshCommand) Run(rawArgs []string) int {
	// Parse and apply global view arguments
	common, rawArgs := arguments.ParseView(rawArgs)
	c.View.Configure(common)

	// Parse and validate flags
	args, diags := arguments.ParseRefresh(rawArgs)

	// Instantiate the view, even if there are flag errors, so that we render
	// diagnostics according to the desired view
	var view views.Refresh
	view = views.NewRefresh(args.ViewType, c.View)

	if diags.HasErrors() {
		view.Diagnostics(diags)
		view.HelpPrompt()
		return 1
	}

	// Check for user-supplied plugin path
	var err error
	if c.pluginPath, err = c.loadPluginPath(); err != nil {
		diags = diags.Append(err)
		view.Diagnostics(diags)
		return 1
	}

	// FIXME: the -input flag value is needed to initialize the backend and the
	// operation, but there is no clear path to pass this value down, so we
	// continue to mutate the Meta object state for now.
	c.Meta.input = args.InputEnabled

	// FIXME: the -parallelism flag is used to control the concurrency of
	// Terraform operations. At the moment, this value is used both to
	// initialize the backend via the ContextOpts field inside CLIOpts, and to
	// set a largely unused field on the Operation request. Again, there is no
	// clear path to pass this value down, so we continue to mutate the Meta
	// object state for now.
	c.Meta.parallelism = args.Operation.Parallelism

	// Prepare the backend with the backend-specific arguments
	be, beDiags := c.PrepareBackend(args.State)
	diags = diags.Append(beDiags)
	if diags.HasErrors() {
		view.Diagnostics(diags)
		return 1
	}

	// Build the operation request
	opReq, opDiags := c.OperationRequest(be, view, args.Operation)
	diags = diags.Append(opDiags)
	if diags.HasErrors() {
		view.Diagnostics(diags)
		return 1
	}

	// Collect variable value and add them to the operation request
	diags = diags.Append(c.GatherVariables(opReq, args.Vars))
	if diags.HasErrors() {
		view.Diagnostics(diags)
		return 1
	}

	// Before we delegate to the backend, we'll print any warning diagnostics
	// we've accumulated here, since the backend will start fresh with its own
	// diagnostics.
	view.Diagnostics(diags)
	diags = nil

	// Perform the operation
	op, err := c.RunOperation(be, opReq)
	if err != nil {
		diags = diags.Append(err)
		view.Diagnostics(diags)
		return 1
	}

	if op.State != nil {
		view.Outputs(op.State.RootModule().OutputValues)
	}

	return op.Result.ExitStatus()
}

func (c *RefreshCommand) PrepareBackend(args *arguments.State) (backend.Enhanced, tfdiags.Diagnostics) {
	// FIXME: we need to apply the state arguments to the meta object here
	// because they are later used when initializing the backend. Carving a
	// path to pass these arguments to the functions that need them is
	// difficult but would make their use easier to understand.
	c.Meta.applyStateArguments(args)

	backendConfig, diags := c.loadBackendConfig(".")
	if diags.HasErrors() {
		return nil, diags
	}

	// Load the backend
	be, beDiags := c.Backend(&BackendOpts{
		Config: backendConfig,
	})
	diags = diags.Append(beDiags)
	if beDiags.HasErrors() {
		return nil, diags
	}

	return be, diags
}

func (c *RefreshCommand) OperationRequest(be backend.Enhanced, view views.Refresh, args *arguments.Operation,
) (*backend.Operation, tfdiags.Diagnostics) {
	var diags tfdiags.Diagnostics

	// Build the operation
	opReq := c.Operation(be)
	opReq.ConfigDir = "."
	opReq.Hooks = view.Hooks()
	opReq.Targets = args.Targets
	opReq.Type = backend.OperationTypeRefresh
	opReq.View = view.Operation()

	var err error
	opReq.ConfigLoader, err = c.initConfigLoader()
	if err != nil {
		diags = diags.Append(fmt.Errorf("Failed to initialize config loader: %s", err))
		return nil, diags
	}

	return opReq, diags
}

func (c *RefreshCommand) GatherVariables(opReq *backend.Operation, args *arguments.Vars) tfdiags.Diagnostics {
	var diags tfdiags.Diagnostics

	// FIXME the arguments package currently trivially gathers variable related
	// arguments in a heterogenous slice, in order to minimize the number of
	// code paths gathering variables during the transition to this structure.
	// Once all commands that gather variables have been converted to this
	// structure, we could move the variable gathering code to the arguments
	// package directly, removing this shim layer.

	varArgs := args.All()
	items := make([]rawFlag, len(varArgs))
	for i := range varArgs {
		items[i].Name = varArgs[i].Name
		items[i].Value = varArgs[i].Value
	}
	c.Meta.variableArgs = rawFlags{items: &items}
	opReq.Variables, diags = c.collectVariableValues()

	return diags
}

func (c *RefreshCommand) Help() string {
	helpText := `
Usage: terraform [global options] refresh [options]

  Update the state file of your infrastructure with metadata that matches
  the physical resources they are tracking.

  This will not modify your infrastructure, but it can modify your
  state file to update metadata. This metadata might cause new changes
  to occur when you generate a plan or call apply next.

Options:

  -compact-warnings   If Terraform produces any warnings that are not
                      accompanied by errors, show them in a more compact form
                      that includes only the summary messages.

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

  -lock=false         Don't hold a state lock during the operation. This is
                      dangerous if others might concurrently run commands
                      against the same workspace.

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

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

  -target=resource    Resource to target. Operation will be limited to this
                      resource and its dependencies. This flag can be used
                      multiple times.

  -var 'foo=bar'      Set a variable in the Terraform configuration. This
                      flag can be set multiple times.

  -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.

  -state, state-out, and -backup are legacy options supported for the local
  backend only. For more information, see the local backend's documentation.
`
	return strings.TrimSpace(helpText)
}

func (c *RefreshCommand) Synopsis() string {
	return "Update the state to match remote systems"
}