package command

import (
	"bytes"
	"context"
	"errors"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	plugin "github.com/hashicorp/go-plugin"
	"github.com/hashicorp/terraform-svchost/disco"
	"github.com/hashicorp/terraform/addrs"
	"github.com/hashicorp/terraform/backend"
	"github.com/hashicorp/terraform/backend/local"
	"github.com/hashicorp/terraform/command/format"
	"github.com/hashicorp/terraform/command/webbrowser"
	"github.com/hashicorp/terraform/configs/configload"
	"github.com/hashicorp/terraform/helper/experiment"
	"github.com/hashicorp/terraform/helper/wrappedstreams"
	"github.com/hashicorp/terraform/internal/getproviders"
	"github.com/hashicorp/terraform/providers"
	"github.com/hashicorp/terraform/provisioners"
	"github.com/hashicorp/terraform/terraform"
	"github.com/hashicorp/terraform/tfdiags"
	"github.com/mitchellh/cli"
	"github.com/mitchellh/colorstring"
)

// Meta are the meta-options that are available on all or most commands.
type Meta struct {
	// The exported fields below should be set by anyone using a
	// command with a Meta field. These are expected to be set externally
	// (not from within the command itself).

	// OriginalWorkingDir, if set, is the actual working directory where
	// Terraform was run from. This might not be the _actual_ current working
	// directory, because users can add the -chdir=... option to the beginning
	// of their command line to ask Terraform to switch.
	//
	// Most things should just use the current working directory in order to
	// respect the user's override, but we retain this for exceptional
	// situations where we need to refer back to the original working directory
	// for some reason.
	OriginalWorkingDir string

	Color            bool             // True if output should be colored
	GlobalPluginDirs []string         // Additional paths to search for plugins
	PluginOverrides  *PluginOverrides // legacy overrides from .terraformrc file
	Ui               cli.Ui           // Ui for output

	// ExtraHooks are extra hooks to add to the context.
	ExtraHooks []terraform.Hook

	// Services provides access to remote endpoint information for
	// "terraform-native' services running at a specific user-facing hostname.
	Services *disco.Disco

	// RunningInAutomation indicates that commands are being run by an
	// automated system rather than directly at a command prompt.
	//
	// This is a hint to various command routines that it may be confusing
	// to print out messages that suggest running specific follow-up
	// commands, since the user consuming the output will not be
	// in a position to run such commands.
	//
	// The intended use-case of this flag is when Terraform is running in
	// some sort of workflow orchestration tool which is abstracting away
	// the specific commands being run.
	RunningInAutomation bool

	// CLIConfigDir is the directory from which CLI configuration files were
	// read by the caller and the directory where any changes to CLI
	// configuration files by commands should be made.
	//
	// If this is empty then no configuration directory is available and
	// commands which require one cannot proceed.
	CLIConfigDir string

	// PluginCacheDir, if non-empty, enables caching of downloaded plugins
	// into the given directory.
	PluginCacheDir string

	// ProviderSource allows determining the available versions of a provider
	// and determines where a distribution package for a particular
	// provider version can be obtained.
	ProviderSource getproviders.Source

	// OverrideDataDir, if non-empty, overrides the return value of the
	// DataDir method for situations where the local .terraform/ directory
	// is not suitable, e.g. because of a read-only filesystem.
	OverrideDataDir string

	// BrowserLauncher is used by commands that need to open a URL in a
	// web browser.
	BrowserLauncher webbrowser.Launcher

	// When this channel is closed, the command will be cancelled.
	ShutdownCh <-chan struct{}

	// UnmanagedProviders are a set of providers that exist as processes predating Terraform, which Terraform should use but not worry about the lifecycle of.
	UnmanagedProviders map[addrs.Provider]*plugin.ReattachConfig

	//----------------------------------------------------------
	// Protected: commands can set these
	//----------------------------------------------------------

	// Modify the data directory location. This should be accessed through the
	// DataDir method.
	dataDir string

	// pluginPath is a user defined set of directories to look for plugins.
	// This is set during init with the `-plugin-dir` flag, saved to a file in
	// the data directory.
	// This overrides all other search paths when discovering plugins.
	pluginPath []string

	ignorePluginChecksum bool

	// Override certain behavior for tests within this package
	testingOverrides *testingOverrides

	//----------------------------------------------------------
	// Private: do not set these
	//----------------------------------------------------------

	// configLoader is a shared configuration loader that is used by
	// LoadConfig and other commands that access configuration files.
	// It is initialized on first use.
	configLoader *configload.Loader

	// backendState is the currently active backend state
	backendState *terraform.BackendState

	// Variables for the context (private)
	variableArgs rawFlags
	input        bool

	// Targets for this context (private)
	targets []addrs.Targetable

	// Internal fields
	color bool
	oldUi cli.Ui

	// The fields below are expected to be set by the command via
	// command line flags. See the Apply command for an example.
	//
	// statePath is the path to the state file. If this is empty, then
	// no state will be loaded. It is also okay for this to be a path to
	// a file that doesn't exist; it is assumed that this means that there
	// is simply no state.
	//
	// stateOutPath is used to override the output path for the state.
	// If not provided, the StatePath is used causing the old state to
	// be overridden.
	//
	// backupPath is used to backup the state file before writing a modified
	// version. It defaults to stateOutPath + DefaultBackupExtension
	//
	// parallelism is used to control the number of concurrent operations
	// allowed when walking the graph
	//
	// provider is to specify specific resource providers
	//
	// stateLock is set to false to disable state locking
	//
	// stateLockTimeout is the optional duration to retry a state locks locks
	// when it is already locked by another process.
	//
	// forceInitCopy suppresses confirmation for copying state data during
	// init.
	//
	// reconfigure forces init to ignore any stored configuration.
	//
	// compactWarnings (-compact-warnings) selects a more compact presentation
	// of warnings in the output when they are not accompanied by errors.
	statePath        string
	stateOutPath     string
	backupPath       string
	parallelism      int
	provider         string
	stateLock        bool
	stateLockTimeout time.Duration
	forceInitCopy    bool
	reconfigure      bool
	compactWarnings  bool

	// Used with the import command to allow import of state when no matching config exists.
	allowMissingConfig bool
}

type PluginOverrides struct {
	Providers    map[string]string
	Provisioners map[string]string
}

type testingOverrides struct {
	Providers    map[addrs.Provider]providers.Factory
	Provisioners map[string]provisioners.Factory
}

// initStatePaths is used to initialize the default values for
// statePath, stateOutPath, and backupPath
func (m *Meta) initStatePaths() {
	if m.statePath == "" {
		m.statePath = DefaultStateFilename
	}
	if m.stateOutPath == "" {
		m.stateOutPath = m.statePath
	}
	if m.backupPath == "" {
		m.backupPath = m.stateOutPath + DefaultBackupExtension
	}
}

// StateOutPath returns the true output path for the state file
func (m *Meta) StateOutPath() string {
	return m.stateOutPath
}

// Colorize returns the colorization structure for a command.
func (m *Meta) Colorize() *colorstring.Colorize {
	return &colorstring.Colorize{
		Colors:  colorstring.DefaultColors,
		Disable: !m.color,
		Reset:   true,
	}
}

// DataDir returns the directory where local data will be stored.
// Defaults to DefaultDataDir in the current working directory.
func (m *Meta) DataDir() string {
	if m.OverrideDataDir != "" {
		return m.OverrideDataDir
	}
	return DefaultDataDir
}

const (
	// InputModeEnvVar is the environment variable that, if set to "false" or
	// "0", causes terraform commands to behave as if the `-input=false` flag was
	// specified.
	InputModeEnvVar = "TF_INPUT"
)

// InputMode returns the type of input we should ask for in the form of
// terraform.InputMode which is passed directly to Context.Input.
func (m *Meta) InputMode() terraform.InputMode {
	if test || !m.input {
		return 0
	}

	if envVar := os.Getenv(InputModeEnvVar); envVar != "" {
		if v, err := strconv.ParseBool(envVar); err == nil {
			if !v {
				return 0
			}
		}
	}

	var mode terraform.InputMode
	mode |= terraform.InputModeProvider

	return mode
}

// UIInput returns a UIInput object to be used for asking for input.
func (m *Meta) UIInput() terraform.UIInput {
	return &UIInput{
		Colorize: m.Colorize(),
	}
}

// StdinPiped returns true if the input is piped.
func (m *Meta) StdinPiped() bool {
	fi, err := wrappedstreams.Stdin().Stat()
	if err != nil {
		// If there is an error, let's just say its not piped
		return false
	}

	return fi.Mode()&os.ModeNamedPipe != 0
}

// InterruptibleContext returns a context.Context that will be cancelled
// if the process is interrupted by a platform-specific interrupt signal.
//
// As usual with cancelable contexts, the caller must always call the given
// cancel function once all operations are complete in order to make sure
// that the context resources will still be freed even if there is no
// interruption.
func (m *Meta) InterruptibleContext() (context.Context, context.CancelFunc) {
	base := context.Background()
	if m.ShutdownCh == nil {
		// If we're running in a unit testing context without a shutdown
		// channel populated then we'll return an uncancelable channel.
		return base, func() {}
	}

	ctx, cancel := context.WithCancel(base)
	go func() {
		select {
		case <-m.ShutdownCh:
			cancel()
		case <-ctx.Done():
			// finished without being interrupted
		}
	}()
	return ctx, cancel
}

// RunOperation executes the given operation on the given backend, blocking
// until that operation completes or is interrupted, and then returns
// the RunningOperation object representing the completed or
// aborted operation that is, despite the name, no longer running.
//
// An error is returned if the operation either fails to start or is cancelled.
// If the operation runs to completion then no error is returned even if the
// operation itself is unsuccessful. Use the "Result" field of the
// returned operation object to recognize operation-level failure.
func (m *Meta) RunOperation(b backend.Enhanced, opReq *backend.Operation) (*backend.RunningOperation, error) {
	if opReq.ConfigDir != "" {
		opReq.ConfigDir = m.normalizePath(opReq.ConfigDir)
	}

	op, err := b.Operation(context.Background(), opReq)
	if err != nil {
		return nil, fmt.Errorf("error starting operation: %s", err)
	}

	// Wait for the operation to complete or an interrupt to occur
	select {
	case <-m.ShutdownCh:
		// gracefully stop the operation
		op.Stop()

		// Notify the user
		m.Ui.Output(outputInterrupt)

		// Still get the result, since there is still one
		select {
		case <-m.ShutdownCh:
			m.Ui.Error(
				"Two interrupts received. Exiting immediately. Note that data\n" +
					"loss may have occurred.")

			// cancel the operation completely
			op.Cancel()

			// the operation should return asap
			// but timeout just in case
			select {
			case <-op.Done():
			case <-time.After(5 * time.Second):
			}

			return nil, errors.New("operation canceled")

		case <-op.Done():
			// operation completed after Stop
		}
	case <-op.Done():
		// operation completed normally
	}

	return op, nil
}

const (
	ProviderSkipVerifyEnvVar = "TF_SKIP_PROVIDER_VERIFY"
)

// contextOpts returns the options to use to initialize a Terraform
// context with the settings from this Meta.
func (m *Meta) contextOpts() (*terraform.ContextOpts, error) {
	workspace, err := m.Workspace()
	if err != nil {
		return nil, err
	}

	var opts terraform.ContextOpts
	opts.Hooks = []terraform.Hook{m.uiHook()}
	opts.Hooks = append(opts.Hooks, m.ExtraHooks...)

	opts.Targets = m.targets
	opts.UIInput = m.UIInput()
	opts.Parallelism = m.parallelism

	// If testingOverrides are set, we'll skip the plugin discovery process
	// and just work with what we've been given, thus allowing the tests
	// to provide mock providers and provisioners.
	if m.testingOverrides != nil {
		opts.Providers = m.testingOverrides.Providers
		opts.Provisioners = m.testingOverrides.Provisioners
	} else {
		providerFactories, err := m.providerFactories()
		if err != nil {
			// providerFactories can fail if the plugin selections file is
			// invalid in some way, but we don't have any way to report that
			// from here so we'll just behave as if no providers are available
			// in that case. However, we will produce a warning in case this
			// shows up unexpectedly and prompts a bug report.
			// This situation shouldn't arise commonly in practice because
			// the selections file is generated programmatically.
			log.Printf("[WARN] Failed to determine selected providers: %s", err)

			// variable providerFactories may now be incomplete, which could
			// lead to errors reported downstream from here. providerFactories
			// tries to populate as many providers as possible even in an
			// error case, so that operations not using problematic providers
			// can still succeed.
		}
		opts.Providers = providerFactories
		opts.Provisioners = m.provisionerFactories()
	}

	opts.ProviderSHA256s = m.providerPluginsLock().Read()
	if v := os.Getenv(ProviderSkipVerifyEnvVar); v != "" {
		opts.SkipProviderVerify = true
	}

	opts.Meta = &terraform.ContextMeta{
		Env:                workspace,
		OriginalWorkingDir: m.OriginalWorkingDir,
	}

	return &opts, nil
}

// defaultFlagSet creates a default flag set for commands.
func (m *Meta) defaultFlagSet(n string) *flag.FlagSet {
	f := flag.NewFlagSet(n, flag.ContinueOnError)
	f.SetOutput(ioutil.Discard)

	// Set the default Usage to empty
	f.Usage = func() {}

	return f
}

// extendedFlagSet adds custom flags that are mostly used by commands
// that are used to run an operation like plan or apply.
func (m *Meta) extendedFlagSet(n string) *flag.FlagSet {
	f := m.defaultFlagSet(n)

	f.BoolVar(&m.input, "input", true, "input")
	f.Var((*FlagTargetSlice)(&m.targets), "target", "resource to target")
	f.BoolVar(&m.compactWarnings, "compact-warnings", false, "use compact warnings")

	if m.variableArgs.items == nil {
		m.variableArgs = newRawFlags("-var")
	}
	varValues := m.variableArgs.Alias("-var")
	varFiles := m.variableArgs.Alias("-var-file")
	f.Var(varValues, "var", "variables")
	f.Var(varFiles, "var-file", "variable file")

	// Experimental features
	experiment.Flag(f)

	// commands that bypass locking will supply their own flag on this var,
	// but set the initial meta value to true as a failsafe.
	m.stateLock = true

	return f
}

// process will process the meta-parameters out of the arguments. This
// will potentially modify the args in-place. It will return the resulting
// slice.
func (m *Meta) process(args []string) []string {
	// We do this so that we retain the ability to technically call
	// process multiple times, even if we have no plans to do so
	if m.oldUi != nil {
		m.Ui = m.oldUi
	}

	// Set colorization
	m.color = m.Color
	i := 0 // output index
	for _, v := range args {
		if v == "-no-color" {
			m.color = false
			m.Color = false
		} else {
			// copy and increment index
			args[i] = v
			i++
		}
	}
	args = args[:i]

	// Set the UI
	m.oldUi = m.Ui
	m.Ui = &cli.ConcurrentUi{
		Ui: &ColorizeUi{
			Colorize:   m.Colorize(),
			ErrorColor: "[red]",
			WarnColor:  "[yellow]",
			Ui:         m.oldUi,
		},
	}

	return args
}

// uiHook returns the UiHook to use with the context.
func (m *Meta) uiHook() *UiHook {
	return &UiHook{
		Colorize: m.Colorize(),
		Ui:       m.Ui,
	}
}

// confirm asks a yes/no confirmation.
func (m *Meta) confirm(opts *terraform.InputOpts) (bool, error) {
	if !m.Input() {
		return false, errors.New("input is disabled")
	}

	for i := 0; i < 2; i++ {
		v, err := m.UIInput().Input(context.Background(), opts)
		if err != nil {
			return false, fmt.Errorf(
				"Error asking for confirmation: %s", err)
		}

		switch strings.ToLower(v) {
		case "no":
			return false, nil
		case "yes":
			return true, nil
		}
	}
	return false, nil
}

// showDiagnostics displays error and warning messages in the UI.
//
// "Diagnostics" here means the Diagnostics type from the tfdiag package,
// though as a convenience this function accepts anything that could be
// passed to the "Append" method on that type, converting it to Diagnostics
// before displaying it.
//
// Internally this function uses Diagnostics.Append, and so it will panic
// if given unsupported value types, just as Append does.
func (m *Meta) showDiagnostics(vals ...interface{}) {
	var diags tfdiags.Diagnostics
	diags = diags.Append(vals...)
	diags.Sort()

	if len(diags) == 0 {
		return
	}

	diags = diags.ConsolidateWarnings(1)

	// Since warning messages are generally competing
	if m.compactWarnings {
		// If the user selected compact warnings and all of the diagnostics are
		// warnings then we'll use a more compact representation of the warnings
		// that only includes their summaries.
		// We show full warnings if there are also errors, because a warning
		// can sometimes serve as good context for a subsequent error.
		useCompact := true
		for _, diag := range diags {
			if diag.Severity() != tfdiags.Warning {
				useCompact = false
				break
			}
		}
		if useCompact {
			msg := format.DiagnosticWarningsCompact(diags, m.Colorize())
			msg = "\n" + msg + "\nTo see the full warning notes, run Terraform without -compact-warnings.\n"
			m.Ui.Warn(msg)
			return
		}
	}

	for _, diag := range diags {
		// TODO: Actually measure the terminal width and pass it here.
		// For now, we don't have easy access to the writer that
		// ui.Error (etc) are writing to and thus can't interrogate
		// to see if it's a terminal and what size it is.
		msg := format.Diagnostic(diag, m.configSources(), m.Colorize(), 78)
		switch diag.Severity() {
		case tfdiags.Error:
			m.Ui.Error(msg)
		case tfdiags.Warning:
			m.Ui.Warn(msg)
		default:
			m.Ui.Output(msg)
		}
	}
}

// outputShadowError outputs the error from ctx.ShadowError. If the
// error is nil then nothing happens. If output is false then it isn't
// outputted to the user (you can define logic to guard against outputting).
func (m *Meta) outputShadowError(err error, output bool) bool {
	// Do nothing if no error
	if err == nil {
		return false
	}

	// If not outputting, do nothing
	if !output {
		return false
	}

	// Write the shadow error output to a file
	path := fmt.Sprintf("terraform-error-%d.log", time.Now().UTC().Unix())
	if err := ioutil.WriteFile(path, []byte(err.Error()), 0644); err != nil {
		// If there is an error writing it, just let it go
		log.Printf("[ERROR] Error writing shadow error: %s", err)
		return false
	}

	// Output!
	m.Ui.Output(m.Colorize().Color(fmt.Sprintf(
		"[reset][bold][yellow]\nExperimental feature failure! Please report a bug.\n\n"+
			"This is not an error. Your Terraform operation completed successfully.\n"+
			"Your real infrastructure is unaffected by this message.\n\n"+
			"[reset][yellow]While running, Terraform sometimes tests experimental features in the\n"+
			"background. These features cannot affect real state and never touch\n"+
			"real infrastructure. If the features work properly, you see nothing.\n"+
			"If the features fail, this message appears.\n\n"+
			"You can report an issue at: https://github.com/hashicorp/terraform/issues\n\n"+
			"The failure was written to %q. Please\n"+
			"double check this file contains no sensitive information and report\n"+
			"it with your issue.\n\n"+
			"This is not an error. Your terraform operation completed successfully\n"+
			"and your real infrastructure is unaffected by this message.",
		path,
	)))

	return true
}

// WorkspaceNameEnvVar is the name of the environment variable that can be used
// to set the name of the Terraform workspace, overriding the workspace chosen
// by `terraform workspace select`.
//
// Note that this environment variable is ignored by `terraform workspace new`
// and `terraform workspace delete`.
const WorkspaceNameEnvVar = "TF_WORKSPACE"

var invalidWorkspaceNameEnvVar = fmt.Errorf("Invalid workspace name set using %s", WorkspaceNameEnvVar)

// Workspace returns the name of the currently configured workspace, corresponding
// to the desired named state.
func (m *Meta) Workspace() (string, error) {
	current, overridden := m.WorkspaceOverridden()
	if overridden && !validWorkspaceName(current) {
		return "", invalidWorkspaceNameEnvVar
	}
	return current, nil
}

// WorkspaceOverridden returns the name of the currently configured workspace,
// corresponding to the desired named state, as well as a bool saying whether
// this was set via the TF_WORKSPACE environment variable.
func (m *Meta) WorkspaceOverridden() (string, bool) {
	if envVar := os.Getenv(WorkspaceNameEnvVar); envVar != "" {
		return envVar, true
	}

	envData, err := ioutil.ReadFile(filepath.Join(m.DataDir(), local.DefaultWorkspaceFile))
	current := string(bytes.TrimSpace(envData))
	if current == "" {
		current = backend.DefaultStateName
	}

	if err != nil && !os.IsNotExist(err) {
		// always return the default if we can't get a workspace name
		log.Printf("[ERROR] failed to read current workspace: %s", err)
	}

	return current, false
}

// SetWorkspace saves the given name as the current workspace in the local
// filesystem.
func (m *Meta) SetWorkspace(name string) error {
	err := os.MkdirAll(m.DataDir(), 0755)
	if err != nil {
		return err
	}

	err = ioutil.WriteFile(filepath.Join(m.DataDir(), local.DefaultWorkspaceFile), []byte(name), 0644)
	if err != nil {
		return err
	}
	return nil
}

// isAutoVarFile determines if the file ends with .auto.tfvars or .auto.tfvars.json
func isAutoVarFile(path string) bool {
	return strings.HasSuffix(path, ".auto.tfvars") ||
		strings.HasSuffix(path, ".auto.tfvars.json")
}