package cli

import (
	"errors"
	"flag"
	"fmt"
	"io"
	"os"
	"strconv"
	"strings"
	"syscall"
	"time"

	"werkdock/internal/engine"
	"werkdock/internal/instance"
	"werkdock/internal/store"
)

// The lifecycle verbs are thin frontends over the instance package
// (RFC 0005): they parse docker's flags, resolve instances by id,
// prefix, or name, and print what docker prints.

func manager() (instance.Manager, error) {
	st, err := store.Default()
	if err != nil {
		return instance.Manager{}, err
	}
	return instance.Manager{Root: st.Root}, nil
}

// createCmd is `docker create`: the run flags, an instance directory,
// no start. Prints the id.
func createCmd(args []string) int {
	opts, err := parseRun(args, os.LookupEnv)
	if err != nil {
		return fail(err)
	}
	if opts.Detach {
		return fail(errors.New("create takes no -d: the instance is not started; werkdock start ID does that"))
	}
	st, err := store.Default()
	if err != nil {
		return fail(err)
	}
	inst, err := createInstance(st, opts, false)
	if err != nil {
		return fail(err)
	}
	fmt.Println(inst.Config.ID)
	return 0
}

// startCmd is `docker start INSTANCE...`: each is started under a
// detached supervisor; the name is printed as docker does.
func startCmd(args []string) int {
	fs := flag.NewFlagSet("start", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	refuse(fs, "a", "start does not attach; werkdock logs -f ID follows the output")
	refuse(fs, "attach", "start does not attach; werkdock logs -f ID follows the output")
	refuse(fs, "i", "start does not attach; werkdock logs -f ID follows the output")
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) == 0 {
		return fail(errors.New("start needs an INSTANCE (werkdock start INSTANCE...)"))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	return eachInstance(m, fs.Args(), func(inst *instance.Instance) error {
		return startDetached(m, inst)
	})
}

// eachInstance applies fn to every instance named, reports failures
// per instance and prints the argument on success, docker's way; exit
// 125 if any failed.
func eachInstance(m instance.Manager, keys []string, fn func(*instance.Instance) error) int {
	code := 0
	for _, key := range keys {
		inst, err := m.Get(key)
		if err == nil {
			err = fn(inst)
		}
		if err != nil {
			fmt.Fprintf(os.Stderr, "werkdock: %v\n", err)
			code = exitCLIError
			continue
		}
		fmt.Println(key)
	}
	return code
}

func stopCmd(args []string) int {
	fs := flag.NewFlagSet("stop", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	var timeout int
	fs.IntVar(&timeout, "t", 10, "seconds to wait for the command to exit on SIGTERM before SIGKILL")
	fs.IntVar(&timeout, "time", 10, "seconds to wait for the command to exit on SIGTERM before SIGKILL")
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) == 0 {
		return fail(errors.New("stop needs an INSTANCE (werkdock stop [-t SECONDS] INSTANCE...)"))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	return eachInstance(m, fs.Args(), func(inst *instance.Instance) error {
		return m.Stop(inst, time.Duration(timeout)*time.Second)
	})
}

func killCmd(args []string) int {
	fs := flag.NewFlagSet("kill", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	var signame string
	fs.StringVar(&signame, "s", "KILL", "signal to send")
	fs.StringVar(&signame, "signal", "KILL", "signal to send")
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) == 0 {
		return fail(errors.New("kill needs an INSTANCE (werkdock kill [-s SIGNAL] INSTANCE...)"))
	}
	sig, err := parseSignal(signame)
	if err != nil {
		return fail(err)
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	return eachInstance(m, fs.Args(), func(inst *instance.Instance) error {
		return m.Kill(inst, sig)
	})
}

var signals = map[string]syscall.Signal{
	"HUP": syscall.SIGHUP, "INT": syscall.SIGINT, "QUIT": syscall.SIGQUIT, "KILL": syscall.SIGKILL,
	"USR1": syscall.SIGUSR1, "USR2": syscall.SIGUSR2, "TERM": syscall.SIGTERM, "WINCH": syscall.SIGWINCH,
}

// parseSignal accepts docker's spellings: a number, NAME, or SIGNAME.
func parseSignal(s string) (syscall.Signal, error) {
	if n, err := strconv.Atoi(s); err == nil && n > 0 {
		return syscall.Signal(n), nil
	}
	name := strings.TrimPrefix(strings.ToUpper(s), "SIG")
	if sig, ok := signals[name]; ok {
		return sig, nil
	}
	return 0, fmt.Errorf("unknown signal %q", s)
}

func rmCmd(args []string) int {
	fs := flag.NewFlagSet("rm", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	var force bool
	fs.BoolVar(&force, "f", false, "kill a running instance before removing it")
	fs.BoolVar(&force, "force", false, "kill a running instance before removing it")
	refuse(fs, "v", "anonymous volumes always go with the instance; there are no named volumes to keep")
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) == 0 {
		return fail(errors.New("rm needs an INSTANCE (werkdock rm [-f] INSTANCE...)"))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	return eachInstance(m, fs.Args(), func(inst *instance.Instance) error {
		return m.Remove(inst, force)
	})
}

func waitCmd(args []string) int {
	fs := flag.NewFlagSet("wait", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) == 0 {
		return fail(errors.New("wait needs an INSTANCE (werkdock wait INSTANCE...)"))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	code := 0
	for _, key := range fs.Args() {
		inst, err := m.Get(key)
		if err != nil {
			fmt.Fprintf(os.Stderr, "werkdock: %v\n", err)
			code = exitCLIError
			continue
		}
		exit, err := m.Wait(inst, 0)
		if err != nil {
			fmt.Fprintf(os.Stderr, "werkdock: %v\n", err)
			code = exitCLIError
			continue
		}
		fmt.Println(exit)
	}
	return code
}

func logsCmd(args []string) int {
	fs := flag.NewFlagSet("logs", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	var follow bool
	fs.BoolVar(&follow, "f", false, "keep printing until the instance exits")
	fs.BoolVar(&follow, "follow", false, "keep printing until the instance exits")
	refuse(fs, "t", "werkdock records no timestamps; the files hold the output as written")
	refuse(fs, "timestamps", "werkdock records no timestamps; the files hold the output as written")
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) != 1 {
		return fail(errors.New("logs needs exactly one INSTANCE (werkdock logs [-f] INSTANCE)"))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	inst, err := m.Get(fs.Args()[0])
	if err != nil {
		return fail(err)
	}
	if err := m.Logs(inst, os.Stdout, os.Stderr, follow, nil); err != nil {
		return fail(err)
	}
	return 0
}

// psColumns is `docker ps` default table.
var psColumns = []column{
	{"CONTAINER ID", "{{.ID}}"},
	{"IMAGE", "{{.Image}}"},
	{"COMMAND", "{{.Command}}"},
	{"CREATED", "{{.RunningFor}}"},
	{"STATUS", "{{.Status}}"},
	{"PORTS", "{{.Ports}}"},
	{"NAMES", "{{.Names}}"},
}

// psRow is one instance as `ps --format` sees it, docker's field names.
type psRow struct{ inst *instance.Instance }

func (r psRow) ID() string    { return r.inst.ShortID() }
func (r psRow) Image() string { return r.inst.Config.Image }
func (r psRow) Names() string { return r.inst.Config.Name }
func (r psRow) CreatedAt() string {
	return r.inst.Config.Created.Format("2006-01-02 15:04:05 -0700 MST")
}
func (r psRow) RunningFor() string {
	return humanDuration(time.Since(r.inst.Config.Created)) + " ago"
}

// Ports is always empty: the sandbox shares the host's network, so a
// service is reachable at the port it binds, without a mapping.
func (r psRow) Ports() string { return "" }

// Command is the command quoted and cut to 20 characters, as docker's
// default table shows it; --no-trunc is not offered, --format is.
func (r psRow) Command() string {
	cmd := strings.Join(r.inst.Config.Spec.Command, " ")
	if len(cmd) > 20 {
		cmd = cmd[:19] + "…"
	}
	return strconv.Quote(cmd)
}

// State is the lifecycle word; Status the sentence docker prints.
func (r psRow) State() string { return string(r.inst.State.Status) }
func (r psRow) Status() string {
	s := r.inst.State
	switch s.Status {
	case instance.StatusRunning:
		return "Up " + humanDuration(time.Since(s.StartedAt))
	case instance.StatusExited:
		return fmt.Sprintf("Exited (%d) %s ago", s.ExitCode, humanDuration(time.Since(s.FinishedAt)))
	}
	return "Created"
}

func psCmd(args []string) int {
	fs := flag.NewFlagSet("ps", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	var all, quiet bool
	var format string
	fs.BoolVar(&all, "a", false, "show stopped and created instances too")
	fs.BoolVar(&all, "all", false, "show stopped and created instances too")
	fs.BoolVar(&quiet, "q", false, "print ids only")
	fs.BoolVar(&quiet, "quiet", false, "print ids only")
	fs.StringVar(&format, "format", "", "Go template or \"table [TEMPLATE]\" over .ID .Image .Command .CreatedAt .RunningFor .Status .State .Ports .Names")
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) != 0 {
		return fail(fmt.Errorf("ps takes no arguments (got %q)", fs.Args()))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	instances, err := m.List()
	if err != nil {
		return fail(err)
	}
	var rows []interface{}
	for _, inst := range instances {
		if !all && !inst.Running() {
			continue
		}
		rows = append(rows, psRow{inst: inst})
	}
	switch {
	case quiet:
		for _, row := range rows {
			fmt.Println(row.(psRow).ID())
		}
	default:
		if format == "" {
			format = "table"
		}
		if err := printFormatted(os.Stdout, format, psColumns, rows); err != nil {
			return fail(err)
		}
	}
	return 0
}

// execCmd runs a second command in an instance's sandbox: the same
// rootfs, mounts, uid, environment, and — because /run and the
// anonymous volumes are directories of the instance — the same
// sockets and data. Not the same pid namespace: the instance's
// processes are not visible.
func execCmd(args []string) int {
	fs := flag.NewFlagSet("exec", flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	var envs stringList
	var workdir, user string
	var interactive bool
	fs.Var(&envs, "e", "environment variable KEY=VALUE")
	fs.Var(&envs, "env", "environment variable KEY=VALUE")
	fs.StringVar(&workdir, "w", "", "working directory")
	fs.StringVar(&workdir, "workdir", "", "working directory")
	fs.StringVar(&user, "u", "", "user[:group] to appear as")
	fs.StringVar(&user, "user", "", "user[:group] to appear as")
	fs.BoolVar(&interactive, "i", false, "pass stdin to the command")
	fs.BoolVar(&interactive, "interactive", false, "pass stdin to the command")
	refuse(fs, "t", "werkdock allocates no pseudo-terminal; run without -t")
	refuse(fs, "tty", "werkdock allocates no pseudo-terminal; run without -t")
	refuse(fs, "d", "a detached exec has no instance to record it; use run -d for a second service")
	refuse(fs, "detach", "a detached exec has no instance to record it; use run -d for a second service")
	if err := fs.Parse(args); err != nil {
		return fail(err)
	}
	if len(fs.Args()) < 2 {
		return fail(errors.New("exec needs an INSTANCE and a COMMAND (werkdock exec [-e K=V] [-w DIR] [-u USER] INSTANCE COMMAND [ARG...])"))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	inst, err := m.Get(fs.Args()[0])
	if err != nil {
		return fail(err)
	}
	if !inst.Running() {
		return fail(fmt.Errorf("instance %s is not running", inst.Config.Name))
	}
	spec := inst.Config.Spec
	spec.Command = fs.Args()[1:]
	if workdir != "" {
		spec.Workdir = workdir
	}
	for _, e := range envs {
		if v, ok := parseEnv(e, os.LookupEnv); ok {
			spec.Env = append(spec.Env, v)
		}
	}
	if user != "" {
		u, err := engine.LookupUser(spec.RootFS, user)
		if err != nil {
			return fail(fmt.Errorf("--user: %w", err))
		}
		spec.UID, spec.GID, spec.Home = u.UID, u.GID, u.Home
	}
	eng := &engine.Bwrap{}
	if interactive {
		eng.Stdin = os.Stdin
	}
	code, err := eng.Run(spec)
	if err != nil {
		return fail(err)
	}
	return code
}

// superviseCmd is the background half of run -d and start: not a
// user verb, started by werkdock itself as `werkdock supervise ID`
// with the output going to the instance's files.
func superviseCmd(args []string) int {
	if len(args) != 1 {
		return fail(errors.New("supervise takes exactly one instance id"))
	}
	m, err := manager()
	if err != nil {
		return fail(err)
	}
	inst, err := m.Get(args[0])
	if err != nil {
		return fail(err)
	}
	code, err := m.Supervise(inst, &engine.Bwrap{}, instance.SuperviseOptions{Record: true})
	if err != nil {
		return fail(err)
	}
	return code
}