// package main provides a tool named sigsum-debug.
//
// Install as follows:
//
//     $ go install -ldflags="-X 'main.someVersion=git commit $(git rev-list -1 HEAD)'"
//
// Usage:
//
//     $ sigsum-debug help
//
package main

import (
	"flag"
	"fmt"
	"log"
	"os"
)

const usage = `sigsum-debug version %s

Usage:
    sigsum-debug help
        Outputs a usage message.

    sigsum-debug genkey
        Outputs a new private key.

    sigsum-debug pubkey
        Reads a private key from stdin and output its public key.

    sigsum-debug hashkey
        Reads a public key from stdin and output its key hash.

    sigsum-debug hashleaf -k PRIVATE_KEY [-s SHARD_HINT]
        Reads data from STDIN and outputs a leaf hash.
        -k, --private-key    Private key to sign with
        -s, --shard-hint     Shard hint to use (Default: 0)

    sigsum-debug sign -k PRIVATE_KEY [-s SHARD_HINT]
        Reads data from STDIN and outputs a signature.
        -k, --private-key    Private key to sign with
        -s, --shard-hint     Shard hint to use (Default: 0)

    sigsum-debug cosign -w WIT_PRIV -l LOG_PUB
        Reads an ASCII signed tree head from STDIN and outputs a cosignature.
        -w, --witness-priv   Witness private key to sign with
        -l, --log-pub        Log public key to verify signed tree head
`

var (
	optPriv, optPub string
	optShardHint uint64

	someVersion = "unknown"
)

func main() {
	log.SetFlags(0)

	var err error
	switch cmd := parseCommand(); cmd.Name() {
	case "help":
		cmd.Usage()
	case "genkey":
		err = CmdGenKey()
	case "pubkey":
		err = CmdPubKey()
	case "hashkey":
		err = CmdHashKey()
	case "hashleaf":
		err = CmdHashLeaf(optPriv, optShardHint)
	case "sign":
		err = CmdSign(optPriv, optShardHint)
	case "cosign":
		err = fmt.Errorf("TODO")
	default:
		err = fmt.Errorf("invalid command %q, try %q", cmd.Name(), "sigsum help")
	}

	if err != nil {
		log.Printf("%s", err)
		os.Exit(1)
	}
}

func parseCommand() *flag.FlagSet {
	args := os.Args
	if len(args) < 2 {
		args = append(args, "")
	}

	fs := flag.NewFlagSet(args[1], flag.ExitOnError)
	fs.Usage = func() {
		log.Printf(usage, someVersion)
	}
	registerOptions(fs)
	fs.Parse(args[2:])
	return fs
}

func registerOptions(fs *flag.FlagSet) {
	switch cmd := fs.Name(); cmd {
	default:
	case "hashleaf":
		registerStringOption(fs, &optPriv, "k", "key", "")
		registerUint64Option(fs, &optShardHint, "s", "shard-hint", 0)
	case "sign":
		registerStringOption(fs, &optPriv, "k", "key", "")
		registerUint64Option(fs, &optShardHint, "s", "shard-hint", 0)
	case "cosign":
		registerStringOption(fs, &optPriv, "w", "--witness-priv", "")
		registerStringOption(fs, &optPub, "l", "--log-pub", "")
	}
}

func registerStringOption(fs *flag.FlagSet, opt *string, short, long, value string) {
	fs.StringVar(opt, short, value, "")
	fs.StringVar(opt, long, value, "")
}

func registerUint64Option(fs *flag.FlagSet, opt *uint64, short, long string, value uint64) {
	fs.Uint64Var(opt, short, value, "")
	fs.Uint64Var(opt, long, value, "")
}