package controller

import (
	"fmt"
	"runtime"
	"strings"
	"sync"

	"github.com/hashicorp/go-hclog"
	"github.com/hashicorp/go-multierror"
	"github.com/hashicorp/vault/sdk/helper/mlock"
	"github.com/hashicorp/watchtower/globals"
	"github.com/hashicorp/watchtower/internal/cmd/base"
	"github.com/hashicorp/watchtower/internal/cmd/commands/controller/config"
	"github.com/hashicorp/watchtower/internal/servers/controller"
	"github.com/mitchellh/cli"
	"github.com/posener/complete"
)

var _ cli.Command = (*Command)(nil)
var _ cli.CommandAutocomplete = (*Command)(nil)

var memProfilerEnabled = false

type Command struct {
	*base.Command
	*base.Server

	ShutdownCh chan struct{}
	SighupCh   chan struct{}
	ReloadedCh chan struct{}
	SigUSR2Ch  chan struct{}

	cleanupGuard sync.Once

	Config *config.Config

	flagConfig                  string
	flagLogLevel                string
	flagLogFormat               string
	flagDev                     bool
	flagDevAdminToken           string
	flagDevControllerListenAddr string
	flagCombineLogs             bool
}

func (c *Command) Synopsis() string {
	return "Start a Watchtower controller"
}

func (c *Command) Help() string {
	helpText := `
Usage: watchtower controller [options]

  Start a controller with a configuration file:

      $ watchtower controller -config=/etc/controller/config.hcl

  For a full list of examples, please see the documentation.

` + c.Flags().Help()
	return strings.TrimSpace(helpText)
}

func (c *Command) Flags() *base.FlagSets {
	set := c.FlagSet(base.FlagSetHTTP)

	f := set.NewFlagSet("Command Options")

	f.StringVar(&base.StringVar{
		Name:   "config",
		Target: &c.flagConfig,
		Completion: complete.PredictOr(
			complete.PredictFiles("*.hcl"),
			complete.PredictFiles("*.json"),
		),
		Usage: "Path to a configuration file.",
	})

	f.StringVar(&base.StringVar{
		Name:       "log-level",
		Target:     &c.flagLogLevel,
		Default:    base.NotSetValue,
		EnvVar:     "WATCHTOWER_LOG_LEVEL",
		Completion: complete.PredictSet("trace", "debug", "info", "warn", "err"),
		Usage: "Log verbosity level. Supported values (in order of more detail to less) are " +
			"\"trace\", \"debug\", \"info\", \"warn\", and \"err\".",
	})

	f.StringVar(&base.StringVar{
		Name:       "log-format",
		Target:     &c.flagLogFormat,
		Default:    base.NotSetValue,
		Completion: complete.PredictSet("standard", "json"),
		Usage:      `Log format. Supported values are "standard" and "json".`,
	})

	f = set.NewFlagSet("Dev Options")

	f.BoolVar(&base.BoolVar{
		Name:   "dev",
		Target: &c.flagDev,
		Usage: "Enable development mode. As the name implies, do not run \"dev\" mode in " +
			"production.",
	})

	f.StringVar(&base.StringVar{
		Name:    "dev-admin-token",
		Target:  &c.flagDevAdminToken,
		Default: "",
		EnvVar:  "WATCHTWER_DEV_ADMIN_TOKEN",
		Usage: "Initial admin token. This only applies when running in \"dev\" " +
			"mode.",
	})

	f.StringVar(&base.StringVar{
		Name:    "dev-listen-address",
		Target:  &c.flagDevControllerListenAddr,
		Default: "127.0.0.1:9200",
		EnvVar:  "WATCHTOWER_DEV_CONTROLLER_LISTEN_ADDRESS",
		Usage:   "Address to bind the controller to in \"dev\" mode.",
	})

	f.BoolVar(&base.BoolVar{
		Name:    "combine-logs",
		Target:  &c.flagCombineLogs,
		Default: false,
		Usage:   "If set, both startup information and logs will be sent to stdout. If not set (the default), startup information will go to stdout and logs will be sent to stderr.",
	})

	return set
}

func (c *Command) AutocompleteArgs() complete.Predictor {
	return complete.PredictNothing
}

func (c *Command) AutocompleteFlags() complete.Flags {
	return c.Flags().Completions()
}

func (c *Command) Run(args []string) int {
	c.Server = base.NewServer()
	c.CombineLogs = c.flagCombineLogs

	if result := c.ParseFlagsAndConfig(args); result > 0 {
		return result
	}

	if memProfilerEnabled {
		c.startMemProfiler()
	}

	if err := c.SetupLogging(c.flagLogLevel, c.flagLogFormat, c.Config.LogLevel, c.Config.LogFormat); err != nil {
		c.UI.Error(err.Error())
		return 1
	}

	if err := c.SetupMetrics(c.UI, c.Config.Telemetry); err != nil {
		c.UI.Error(err.Error())
		return 1
	}

	if err := c.SetupKMSes(c.UI, c.Config.SharedConfig, 2); err != nil {
		c.UI.Error(err.Error())
		return 1
	}

	if c.Config.DefaultMaxRequestDuration != 0 {
		globals.DefaultMaxRequestDuration = c.Config.DefaultMaxRequestDuration
	}

	// If mlockall(2) isn't supported, show a warning. We disable this in dev
	// because it is quite scary to see when first using Vault. We also disable
	// this if the user has explicitly disabled mlock in configuration.
	if !c.flagDev && !c.Config.DisableMlock && !mlock.Supported() {
		c.UI.Warn(base.WrapAtLength(
			"WARNING! mlock is not supported on this system! An mlockall(2)-like " +
				"syscall to prevent memory from being swapped to disk is not " +
				"supported on this system. For better security, only run Vault on " +
				"systems where this call is supported. If you are running Vault " +
				"in a Docker container, provide the IPC_LOCK cap to the container."))
	}

	if err := c.SetupListeners(c.UI, c.Config.SharedConfig); err != nil {
		c.UI.Error(err.Error())
		return 1
	}

	// Write out the PID to the file now that server has successfully started
	if err := c.StorePidFile(c.Config.PidFile); err != nil {
		c.UI.Error(fmt.Sprintf("Error storing PID: %w", err))
		return 1
	}

	if c.flagDev {
		if err := c.CreateDevDatabase(); err != nil {
			c.UI.Error(fmt.Sprintf("Error creating dev database container: %s", err.Error()))
			return 1
		}
		c.ShutdownFuncs = append(c.ShutdownFuncs, c.DestroyDevDatabase)
	}

	defer c.RunShutdownFuncs(c.UI)

	c.PrintInfo(c.UI, "controller")
	c.ReleaseLogGate()

	return c.Start()
}

func (c *Command) ParseFlagsAndConfig(args []string) int {
	var err error

	f := c.Flags()

	if err = f.Parse(args); err != nil {
		c.UI.Error(err.Error())
		return 1
	}

	// Validation
	if !c.flagDev {
		switch {
		case len(c.flagConfig) == 0:
			c.UI.Error("Must specify a config file using -config")
			return 1
		case c.flagDevAdminToken != "":
			c.UI.Warn(base.WrapAtLength(
				"You cannot specify a custom admin token ID outside of \"dev\" mode. " +
					"Your request has been ignored."))
			c.flagDevAdminToken = ""
		}

		if len(c.flagConfig) == 0 {
			c.UI.Error("Must supply a config file with -config")
			return 1
		}
		c.Config, err = config.LoadFile(c.flagConfig)
		if err != nil {
			c.UI.Error("Error parsing config: " + err.Error())
			return 1
		}

	} else {
		c.Config, err = config.Dev()
		if err != nil {
			c.UI.Error(fmt.Sprintf("Error creating dev config: %s", err))
			return 1
		}

		if c.flagDevControllerListenAddr != "" {
			c.Config.Listeners[0].Address = c.flagDevControllerListenAddr
		}
	}

	return 0
}

func (c *Command) Start() int {
	// Instantiate the wait group
	controllerConfig := &controller.Config{
		RawConfig: c.Config,
		Server:    c.Server,
	}

	// Initialize the core
	controller, err := controller.New(controllerConfig)
	if err != nil {
		c.UI.Error(fmt.Sprintf("Error initializing controller: %w", err))
		return 1
	}

	if err := controller.Start(); err != nil {
		c.UI.Error(fmt.Sprint("Error starting controller: %w", err))
		if err := controller.Shutdown(); err != nil {
			c.UI.Error(fmt.Sprintf("Error with controller shutdown: %w", err))
		}
		return 1
	}

	// Wait for shutdown
	shutdownTriggered := false

	for !shutdownTriggered {
		select {
		case <-c.ShutdownCh:
			c.UI.Output("==> Watchtower controller shutdown triggered")

			if err := controller.Shutdown(); err != nil {
				c.UI.Error(fmt.Sprintf("Error with controller shutdown: %w", err))
			}

			shutdownTriggered = true

		case <-c.SighupCh:
			c.UI.Output("==> Watchtower controller reload triggered")

			// Check for new log level
			var level hclog.Level
			var err error
			var newConf *config.Config

			if c.flagConfig == "" {
				goto RUNRELOADFUNCS
			}

			newConf, err = config.LoadFile(c.flagConfig)
			if err != nil {
				c.Logger.Error("could not reload config", "path", c.flagConfig, "error", err)
				goto RUNRELOADFUNCS
			}

			// Ensure at least one config was found.
			if newConf == nil {
				c.Logger.Error("no config found at reload time")
				goto RUNRELOADFUNCS
			}

			// Commented out until we need this
			//controller.SetConfig(config)

			if newConf.LogLevel != "" {
				configLogLevel := strings.ToLower(strings.TrimSpace(newConf.LogLevel))
				switch configLogLevel {
				case "trace":
					level = hclog.Trace
				case "debug":
					level = hclog.Debug
				case "notice", "info", "":
					level = hclog.Info
				case "warn", "warning":
					level = hclog.Warn
				case "err", "error":
					level = hclog.Error
				default:
					c.Logger.Error("unknown log level found on reload", "level", newConf.LogLevel)
					goto RUNRELOADFUNCS
				}
				controller.SetLogLevel(level)
			}

		RUNRELOADFUNCS:
			if err := c.Reload(); err != nil {
				c.UI.Error(fmt.Sprintf("Error(s) were encountered during controller reload: %w", err))
			}

		case <-c.SigUSR2Ch:
			buf := make([]byte, 32*1024*1024)
			n := runtime.Stack(buf[:], true)
			c.Logger.Info("goroutine trace", "stack", string(buf[:n]))
		}
	}

	return 0
}

func (c *Command) Reload() error {
	c.ReloadFuncsLock.RLock()
	defer c.ReloadFuncsLock.RUnlock()

	var reloadErrors *multierror.Error

	for k, relFuncs := range c.ReloadFuncs {
		switch {
		case strings.HasPrefix(k, "listener|"):
			for _, relFunc := range relFuncs {
				if relFunc != nil {
					if err := relFunc(); err != nil {
						reloadErrors = multierror.Append(reloadErrors, fmt.Errorf("error encountered reloading listener: %w", err))
					}
				}
			}
		}
	}

	// Send a message that we reloaded. This prevents "guessing" sleep times
	// in tests.
	select {
	case c.ReloadedCh <- struct{}{}:
	default:
	}

	return reloadErrors.ErrorOrNil()
}