package main

import (
	"dehub"
	"errors"
	"flag"
	"fmt"
	"os"
	"strings"

	"gopkg.in/src-d/go-git.v4/plumbing"
)

type subCmdCtx struct {
	repo *dehub.Repo
	args []string
}

var subCmds = []struct {
	name, descr string
	body        func(sctx subCmdCtx) error
}{
	{
		name:  "commit",
		descr: "commits staged changes to the head of the current branch",
		body: func(sctx subCmdCtx) error {
			flag := flag.NewFlagSet("commit", flag.ExitOnError)
			msg := flag.String("msg", "", "Commit message to use")
			accountID := flag.String("account-id", "", "Account to sign commit as")
			flag.Parse(sctx.args)

			if *msg == "" || *accountID == "" {
				return errors.New("-msg and -account-id are both required")
			}

			cfg, err := sctx.repo.LoadConfig()
			if err != nil {
				return err
			}

			var account dehub.Account
			var ok bool
			for _, account = range cfg.Accounts {
				if account.ID == *accountID {
					ok = true
					break
				}
			}
			if !ok {
				return fmt.Errorf("account ID %q not found in config", *accountID)
			} else if l := len(account.Signifiers); l == 0 || l > 1 {
				return fmt.Errorf("account %q has %d signifiers, only one is supported right now", *accountID, l)
			}

			sig := account.Signifiers[0]
			sigInt, err := sig.Interface()
			if err != nil {
				return fmt.Errorf("could not cast %+v to SignifierInterface: %w", sig, err)
			}

			_, hash, err := sctx.repo.CommitMaster(*msg, *accountID, sigInt)
			if err != nil {
				return err
			}
			fmt.Printf("changes committed to HEAD as %s\n", hash)
			return nil
		},
	},
	{
		name:  "verify",
		descr: "verifies one or more commits as having the proper credentials",
		body: func(sctx subCmdCtx) error {
			flag := flag.NewFlagSet("verify", flag.ExitOnError)
			rev := flag.String("rev", "HEAD", "Revision of commit to verify")
			flag.Parse(sctx.args)

			h, err := sctx.repo.GitRepo.ResolveRevision(plumbing.Revision(*rev))
			if err != nil {
				return fmt.Errorf("could not resolve revision %q: %w", *rev, err)
			}

			if err := sctx.repo.VerifyMasterCommit(*h); err != nil {
				return fmt.Errorf("could not verify commit at %q (%s): %w", *rev, *h, err)
			}

			fmt.Printf("commit at %q (%s) is good to go!\n", *rev, *h)
			return nil
		},
	},
}

func printHelp() {
	fmt.Printf("USAGE: %s <command> [-h]\n\n", os.Args[0])
	fmt.Println("COMMANDS")
	for _, subCmd := range subCmds {
		fmt.Printf("\t%s : %s\n", subCmd.name, subCmd.descr)
	}
}

func exitErr(err error) {
	fmt.Fprintf(os.Stderr, "exiting: %v\n", err)
	os.Stderr.Sync()
	os.Stdout.Sync()
	os.Exit(1)
}

func main() {
	if len(os.Args) < 2 {
		printHelp()
		return
	}

	subCmdName := strings.ToLower(os.Args[1])
	for _, subCmd := range subCmds {
		if subCmd.name != subCmdName {
			continue
		}

		r, err := dehub.OpenRepo(".")
		if err != nil {
			exitErr(err)
		}

		err = subCmd.body(subCmdCtx{
			repo: r,
			args: os.Args[2:],
		})
		if err != nil {
			exitErr(err)
		}
		return
	}

	fmt.Printf("unknown command %q\n\n", subCmdName)
	printHelp()
}