// Package cli is the shark command line.
package cli

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"io"
	"net"
	"os"
	"strconv"
	"strings"
	"time"

	"git.veillax.com/Veillax/shark-expose/internal/api"
	"git.veillax.com/Veillax/shark-expose/internal/config"
	"git.veillax.com/Veillax/shark-expose/internal/expose"
)

// Version is set at build time by cmd/shark.
var Version = "dev"

const usage = `shark exposes a local port through your own Hammerhead.

Usage:
  shark expose [http|https|tcp] <port | host:port> [flags]
  shark login --hammerhead URL --token KEY
  shark ls
  shark version

Examples:
  shark expose 3000                        website on a random name under one of your domains
  shark expose 3000 --password s3cret      ...behind a shared password
  shark expose tcp 25565                   raw TCP on a free public port

Run "shark expose -h" for all flags.
`

// Run executes one command line and returns the exit code. Cancelling ctx is Ctrl+C.
func Run(ctx context.Context, args []string, stdout, stderr io.Writer) int {
	if len(args) == 0 {
		fmt.Fprint(stderr, usage)
		return 2
	}
	var err error
	switch args[0] {
	case "expose":
		err = cmdExpose(ctx, args[1:], stdout, stderr)
	case "login":
		err = cmdLogin(args[1:], stdout)
	case "ls", "list":
		err = cmdList(context.Background(), stdout)
	case "version", "-v", "--version":
		fmt.Fprintln(stdout, "shark", Version)
	case "help", "-h", "--help":
		fmt.Fprint(stdout, usage)
	default:
		fmt.Fprintf(stderr, "unknown command %q\n\n%s", args[0], usage)
		return 2
	}
	if err != nil {
		if errors.Is(err, flag.ErrHelp) {
			return 0
		}
		fmt.Fprintln(stderr, "shark:", err)
		return 1
	}
	return 0
}

func client() (*api.Client, error) {
	cfg, err := config.Load()
	if err != nil {
		return nil, err
	}
	if cfg.Hammerhead == "" || cfg.Token == "" {
		return nil, errors.New("not signed in: run `shark login --hammerhead https://your-hammerhead --token hhk_...` (make a key under Access in the dashboard), or set SHARK_HAMMERHEAD and SHARK_TOKEN")
	}
	return api.New(cfg.Hammerhead, cfg.Token), nil
}

func cmdLogin(args []string, out io.Writer) error {
	fs := flag.NewFlagSet("login", flag.ContinueOnError)
	hh := fs.String("hammerhead", "", "URL of your Hammerhead")
	tok := fs.String("token", os.Getenv("SHARK_TOKEN"), "API key from Access in the dashboard (or set SHARK_TOKEN)")
	if err := fs.Parse(args); err != nil {
		return err
	}
	if *hh == "" || *tok == "" {
		return errors.New("login needs --hammerhead and --token")
	}
	c := api.New(*hh, *tok)
	if _, err := c.List(context.Background()); err != nil {
		return fmt.Errorf("could not sign in: %w", err)
	}
	p, err := config.Save(config.Config{Hammerhead: c.Base, Token: *tok})
	if err != nil {
		return err
	}
	fmt.Fprintf(out, "Signed in to %s. Saved to %s\n", c.Base, p)
	return nil
}

func cmdList(ctx context.Context, out io.Writer) error {
	c, err := client()
	if err != nil {
		return err
	}
	list, err := c.List(ctx)
	if err != nil {
		return err
	}
	if len(list) == 0 {
		fmt.Fprintln(out, "Nothing is exposed.")
	}
	for _, e := range list {
		fmt.Fprintf(out, "%s  %-5s %s  (expires %s)\n", e.ID, e.Proto, e.Address(), time.Until(e.ExpiresAt).Round(time.Second))
	}
	return nil
}

// target parses "3000", ":3000" or "host:3000".
func target(s string) (string, int, error) {
	host := "127.0.0.1"
	if i := strings.LastIndex(s, ":"); i >= 0 {
		if h := s[:i]; h != "" {
			host = h
		}
		s = s[i+1:]
	}
	n, err := strconv.Atoi(s)
	if err != nil || n < 1 || n > 65535 {
		return "", 0, fmt.Errorf("%q is not a port between 1 and 65535", s)
	}
	return strings.Trim(host, "[]"), n, nil
}

// splitArgs lets flags come before or after the positional arguments.
func splitArgs(fs *flag.FlagSet, args []string) ([]string, error) {
	var pos []string
	for {
		if err := fs.Parse(args); err != nil {
			return nil, err
		}
		if fs.NArg() == 0 {
			return pos, nil
		}
		pos = append(pos, fs.Arg(0))
		args = fs.Args()[1:]
	}
}

func cmdExpose(ctx context.Context, args []string, stdout, stderr io.Writer) error {
	fs := flag.NewFlagSet("expose", flag.ContinueOnError)
	fs.SetOutput(stderr)
	name := fs.String("name", "", "label used in the public name and the dashboard")
	ttl := fs.Duration("ttl", 5*time.Minute, "how long Hammerhead keeps the exposure if shark stops talking to it (30s-24h)")
	hostname := fs.String("hostname", "", "website: the full public name (must be under one of your domains)")
	port := fs.Int("port", 0, "public port (default: 80/443 for websites, a free one for tcp)")
	edge := fs.String("edge", "", "edge ID to use (default: any online edge)")
	password := fs.String("password", os.Getenv("SHARK_PASSWORD"), "website: require this password (6+ characters; or set SHARK_PASSWORD)")
	pin := fs.String("pin", "", "website: require this 4-12 digit PIN")
	sso := fs.Bool("sso", false, "website: require a Hammerhead account")
	verbose := fs.Bool("verbose", false, "show the tunnel agent's log")
	fs.Usage = func() {
		fmt.Fprint(stderr, "Usage: shark expose [http|https|tcp] <port | host:port> [flags]\n\n")
		fs.PrintDefaults()
	}
	pos, err := splitArgs(fs, args)
	if err != nil {
		return err
	}
	proto := "http"
	if len(pos) == 2 {
		proto, pos = strings.ToLower(pos[0]), pos[1:]
	}
	if len(pos) != 1 {
		fs.Usage()
		return errors.New("expected a port to expose")
	}
	if proto != "http" && proto != "https" && proto != "tcp" {
		return fmt.Errorf("protocol must be http, https or tcp, not %q", proto)
	}
	host, tport, err := target(pos[0])
	if err != nil {
		return err
	}
	req := api.Request{Proto: proto, Name: *name, TargetHost: host, TargetPort: tport, Port: *port, Hostname: *hostname, EdgeID: *edge}
	if *password != "" || *pin != "" || *sso {
		if proto == "tcp" {
			return errors.New("login protection works for websites, not tcp")
		}
		req.Auth = &api.Auth{Password: *password, Pin: *pin, SSO: *sso}
	}
	c, err := client()
	if err != nil {
		return err
	}
	if !expose.Listening(host, tport) {
		fmt.Fprintf(stderr, "warning: nothing is listening on %s yet\n", net.JoinHostPort(host, strconv.Itoa(tport)))
	}
	o := expose.Options{Request: req, TTL: *ttl, Out: stderr, Verbose: *verbose}
	err = expose.Run(ctx, c, o, func(e api.Exposure) {
		fmt.Fprintf(stdout, "\nshark %s  ->  %s\n\n", e.Address(), net.JoinHostPort(host, strconv.Itoa(tport)))
		if e.Protected {
			fmt.Fprintln(stdout, "Visitors must sign in.")
		}
		if !e.Live {
			fmt.Fprintln(stdout, "The edge has not confirmed the port yet; it may take a moment.")
		}
		fmt.Fprintln(stdout, "Press Ctrl+C to stop.")
	})
	if ctx.Err() != nil && err == nil {
		fmt.Fprintln(stdout, "\nStopped. Removed from Hammerhead.")
	}
	return err
}