// Copyright (C) 2021 Storj Labs, Inc.
// See LICENSE for copying information.

package main

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"time"

	"github.com/spacemonkeygo/monkit/v3"
	"github.com/zeebo/clingy"
	"github.com/zeebo/errs"
	"go.uber.org/zap"
	"golang.org/x/term"

	"storj.io/common/rpc/rpctracing"
	jaeger "storj.io/monkit-jaeger"
	"storj.io/private/version"
)

type external struct {
	interactive bool // controls if interactive input is allowed
	quic        bool // if set, use the quic transport

	dirs struct {
		loaded  bool   // true if Setup has been called
		current string // current config directory
		legacy  string // old config directory
	}

	migration struct {
		migrated bool  // true if a migration has been attempted
		err      error // any error from the migration attempt
	}

	config struct {
		loaded bool                // true if the existing config file is successfully loaded
		values map[string][]string // the existing configuration
	}

	access struct {
		loaded      bool              // true if we've successfully loaded access.json
		defaultName string            // default access name to use from accesses
		accesses    map[string]string // map of all of the stored accesses
	}

	tracing struct {
		traceID      int64  // if non-zero, sets outgoing traces to the given id
		traceAddress string // if non-zero, sampled spans are sent to this trace collector address.
	}
}

func newExternal() *external {
	return &external{}
}

func (ex *external) Setup(f clingy.Flags) {
	ex.interactive = f.Flag(
		"interactive", "Controls if interactive input is allowed", true,
		clingy.Transform(strconv.ParseBool), clingy.Boolean,
		clingy.Advanced,
	).(bool)

	ex.quic = f.Flag(
		"quic", "If set, uses the quic transport", false,
		clingy.Transform(strconv.ParseBool), clingy.Boolean,
		clingy.Advanced,
	).(bool)

	ex.dirs.current = f.Flag(
		"config-dir", "Directory that stores the configuration",
		appDir(false, defaultUplinkSubdir()...),
	).(string)

	ex.dirs.legacy = f.Flag(
		"legacy-config-dir", "Directory that stores legacy configuration. Only used during migration",
		appDir(true, defaultUplinkSubdir()...),
		clingy.Advanced,
	).(string)

	ex.tracing.traceID = f.Flag(
		"trace-id", "Specify a trace id to send a trace to somewhere", int64(0),
		clingy.Transform(transformInt64),
		clingy.Advanced,
	).(int64)

	ex.tracing.traceAddress = f.Flag(
		"trace-addr", "Specify where to send traces", "agent.tracing.datasci.storj.io:5775",
		clingy.Advanced,
	).(string)

	ex.dirs.loaded = true
}

func transformInt64(x string) (int64, error) {
	return strconv.ParseInt(x, 0, 64)
}

func (ex *external) AccessInfoFile() string   { return filepath.Join(ex.dirs.current, "access.json") }
func (ex *external) ConfigFile() string       { return filepath.Join(ex.dirs.current, "config.ini") }
func (ex *external) legacyConfigFile() string { return filepath.Join(ex.dirs.legacy, "config.yaml") }

// Dynamic is called by clingy to look up values for global flags not specified on the command
// line. This call lets us fill in values from config files or environment variables.
func (ex *external) Dynamic(name string) (vals []string, err error) {
	key := "UPLINK_" + strings.ToUpper(strings.ReplaceAll(name, "-", "_"))
	if val, ok := os.LookupEnv(key); ok {
		return []string{val}, nil
	}

	// if we have not yet loaded the directories, we should not try to migrate
	// and load the current config.
	if !ex.dirs.loaded {
		return nil, nil
	}

	// allow errors from migration and configuration loading so that calls to
	// `uplink setup` can happen and write out a new configuration.
	if err := ex.migrate(); err != nil {
		return nil, nil //nolint
	}
	if err := ex.loadConfig(); err != nil {
		return nil, nil //nolint
	}

	return ex.config.values[name], nil
}

// Wrap is called by clingy with the command to be executed.
func (ex *external) Wrap(ctx clingy.Context, cmd clingy.Command) (err error) {
	if err := ex.migrate(); err != nil {
		return err
	}
	if err := ex.loadConfig(); err != nil {
		return err
	}
	if !ex.config.loaded {
		if err := saveInitialConfig(ctx, ex); err != nil {
			return err
		}
	}

	ctxWrapped := ctx

	if ex.tracing.traceAddress != "" {
		versionName := fmt.Sprintf("uplink-release-%s", version.Build.Version.String())
		if !version.Build.Release {
			versionName = fmt.Sprintf("uplink-dev-%s", version.Build.Timestamp.Format(time.RFC3339))
		}
		collector, err := jaeger.NewUDPCollector(zap.L(), ex.tracing.traceAddress, versionName, nil, 0, 0, 0)
		if err != nil {
			return err
		}
		go collector.Run(context.Background())
		defer func() {
			sendErr := collector.Send(context.Background())
			closeErr := collector.Close()
			err = errs.Combine(err, sendErr, closeErr)
		}()
		cancel := jaeger.RegisterJaeger(monkit.Default, collector, jaeger.Options{Fraction: 0})
		defer cancel()
	}

	if ex.tracing.traceID != 0 {
		trace := monkit.NewTrace(ex.tracing.traceID)
		trace.Set(rpctracing.Sampled, true)

		var baseContext context.Context = ctx
		defer mon.Func().RemoteTrace(&baseContext, monkit.NewId(), trace)(&err)

		ctxWrapped = &clingyWrapper{
			Context: baseContext,
			clx:     ctx,
		}
	}

	return cmd.Execute(ctxWrapped)
}

// clingyWrapper lets one swap out the context.Context in a clingy.Context.
type clingyWrapper struct {
	context.Context
	clx clingy.Context
}

func (cw *clingyWrapper) Read(p []byte) (int, error)  { return cw.clx.Read(p) }
func (cw *clingyWrapper) Write(p []byte) (int, error) { return cw.clx.Write(p) }
func (cw *clingyWrapper) Stdin() io.Reader            { return cw.clx.Stdin() }
func (cw *clingyWrapper) Stdout() io.Writer           { return cw.clx.Stdout() }
func (cw *clingyWrapper) Stderr() io.Writer           { return cw.clx.Stderr() }

// PromptInput gets a line of input text from the user and returns an error if
// interactive mode is disabled.
func (ex *external) PromptInput(ctx clingy.Context, prompt string) (input string, err error) {
	if !ex.interactive {
		return "", errs.New("required user input in non-interactive setting")
	}
	fmt.Fprint(ctx.Stdout(), prompt, " ")
	var buf []byte
	var tmp [1]byte
	for {
		_, err := ctx.Stdin().Read(tmp[:])
		if errors.Is(err, io.EOF) {
			break
		} else if err != nil {
			return "", errs.Wrap(err)
		} else if tmp[0] == '\n' {
			break
		}
		buf = append(buf, tmp[0])
	}
	return string(bytes.TrimSpace(buf)), nil
}

// PromptInput gets a line of secret input from the user twice to ensure that
// it is the same value, and returns an error if interactive mode is disabled
// or if the prompt cannot be put into a mode where the typing is not echoed.
func (ex *external) PromptSecret(ctx clingy.Context, prompt string) (secret string, err error) {
	if !ex.interactive {
		return "", errs.New("required secret input in non-interactive setting")
	}

	fh, ok := ctx.Stdin().(interface{ Fd() uintptr })
	if !ok {
		return "", errs.New("unable to request secret from stdin")
	}
	fd := int(fh.Fd())

	for {
		fmt.Fprint(ctx.Stdout(), prompt, " ")

		first, err := term.ReadPassword(fd)
		if err != nil {
			return "", errs.New("unable to request secret from stdin: %w", err)
		}
		fmt.Fprintln(ctx.Stdout())

		fmt.Fprint(ctx.Stdout(), "Again: ")

		second, err := term.ReadPassword(fd)
		if err != nil {
			return "", errs.New("unable to request secret from stdin: %w", err)
		}
		fmt.Fprintln(ctx.Stdout())

		if string(first) != string(second) {
			fmt.Fprintln(ctx.Stdout(), "Values did not match. Try again.")
			fmt.Fprintln(ctx.Stdout())
			continue
		}

		return string(first), nil
	}
}

func defaultUplinkSubdir() []string {
	switch runtime.GOOS {
	case "windows", "darwin":
		return []string{"Storj", "Uplink"}
	default:
		return []string{"storj", "uplink"}
	}
}

// appDir returns best base directory for the currently running operating system. It
// has a legacy bool to have it return the same values that storj.io/common/fpath.ApplicationDir
// would have returned.
func appDir(legacy bool, subdir ...string) string {
	var appdir string
	home := os.Getenv("HOME")

	switch runtime.GOOS {
	case "windows":
		// Windows standards: https://msdn.microsoft.com/en-us/library/windows/apps/hh465094.aspx?f=255&MSPPError=-2147217396
		for _, env := range []string{"AppData", "AppDataLocal", "UserProfile", "Home"} {
			val := os.Getenv(env)
			if val != "" {
				appdir = val
				break
			}
		}
	case "darwin":
		// Mac standards: https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/MacOSXDirectories/MacOSXDirectories.html
		appdir = filepath.Join(home, "Library", "Application Support")
	case "linux":
		fallthrough
	default:
		// Linux standards: https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
		if legacy {
			appdir = os.Getenv("XDG_DATA_HOME")
			if appdir == "" && home != "" {
				appdir = filepath.Join(home, ".local", "share")
			}
		} else {
			appdir = os.Getenv("XDG_CONFIG_HOME")
			if appdir == "" && home != "" {
				appdir = filepath.Join(home, ".config")
			}
		}
	}
	return filepath.Join(append([]string{appdir}, subdir...)...)
}