package cmd

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"filippo.io/age"
	"filippo.io/age/agessh"
	"github.com/urfave/cli/v2"
)

var (
	version = "develop"
	debug   = false
)

func New() *cli.App {
	app := cli.NewApp()
	app.Name = "git-age"
	app.Version = version
	app.Usage = "Git encryption using age"
	app.Commands = []*cli.Command{
		Clean,
		Identity,
		Init,
		Smudge,
		TextConv,
	}
	app.Flags = []cli.Flag{
		&cli.BoolFlag{
			Name:        "debug",
			Aliases:     []string{"d"},
			Usage:       "Debug mode",
			Destination: &debug,
		},
	}
	return app
}

func parseIdentityFile(file string) ([]age.Identity, error) {
	fi, err := os.Open(file)
	if err != nil {
		return nil, err
	}
	defer fi.Close()

	// First try age
	i, err := age.ParseIdentities(fi)
	if err != nil {
		if debug {
			fmt.Fprintf(os.Stderr, "could not parse %q as age identities, trying ssh next: %v\n", file, err)
		}
		ageErr := err

		// Fall back to ssh
		fi.Seek(0, 0)
		content, err := io.ReadAll(fi)
		if err != nil {
			return nil, err
		}
		si, err := agessh.ParseIdentity(content)
		if err != nil {
			return nil, fmt.Errorf("could not parse identity file: age -> %w, ssh -> %w", ageErr, err)
		}
		i = []age.Identity{si}
	}
	return i, nil
}

func ageRecipients(file string) ([]age.Recipient, error) {
	cfg, err := LoadConfig()
	if err != nil {
		return nil, err
	}
	val, ok := cfg[file]
	if !ok {
		return nil, fmt.Errorf("no config found for %q", file)
	}
	return val.Recipients()
}

var ErrNoIdentities = errors.New("no identities found")

func listIdentities() ([]string, error) {
	out, err := cmd("git", "config", "--get-all", "git-age.identity")
	if err != nil {
		if out == "" {
			return nil, ErrNoIdentities
		}
		return nil, err
	}
	return strings.Fields(out), nil
}

func ageIdentities() ([]age.Identity, error) {
	keyFiles, err := listIdentities()
	if err != nil {
		return nil, err
	}

	var identities []age.Identity
	for _, keyFile := range keyFiles {
		i, err := parseIdentityFile(keyFile)
		if err != nil {
			return identities, err
		}
		identities = append(identities, i...)
	}
	return identities, nil
}

func gitBaseDir() (string, error) {
	out, err := cmd("git", "rev-parse", "--show-toplevel")
	if err != nil {
		return "", err
	}
	stdout := strings.TrimSpace(string(out))
	return stdout, nil
}

func gitConfigDir(file string) (string, error) {
	stdout, err := gitBaseDir()
	if err != nil {
		return "", err
	}
	normalFile := strings.ReplaceAll(file, string(filepath.Separator), "!")
	dir := filepath.Join(stdout, ".git", "git-age", normalFile)
	return dir, os.MkdirAll(dir, os.ModePerm)
}

func cmd(command string, args ...string) (string, error) {
	var stdout bytes.Buffer
	c := exec.Command(command, args...)
	c.Stdout = &stdout
	if debug {
		c.Stderr = os.Stderr
	}
	if err := c.Run(); err != nil {
		return "", err
	}
	return stdout.String(), nil
}