// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package cli

import (
	"context"
	"flag"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"

	"golang.org/x/crypto/ssh"

	"go.fuchsia.dev/fuchsia/src/testing/host-target-testing/device"
	"go.fuchsia.dev/fuchsia/tools/botanist/constants"
)

type DeviceConfig struct {
	sshKeyFile       string
	deviceFinderPath string
	deviceName       string
	deviceHostname   string
	sshPrivateKey    ssh.Signer
	SerialSocketPath string
}

func NewDeviceConfig(fs *flag.FlagSet) *DeviceConfig {
	c := &DeviceConfig{}

	testDataPath := filepath.Join(filepath.Dir(os.Args[0]), "test_data", "system-tests")

	fs.StringVar(&c.sshKeyFile, "ssh-private-key", os.Getenv(constants.SSHKeyEnvKey), "SSH private key file that can access the device")
	fs.StringVar(&c.deviceName, "device", os.Getenv(constants.NodenameEnvKey), "device name")
	fs.StringVar(&c.deviceHostname, "device-hostname", os.Getenv(constants.DeviceAddrEnvKey), "device hostname or IPv4/IPv6 address")
	fs.StringVar(&c.deviceFinderPath, "device-finder-path", filepath.Join(testDataPath, "device-finder"), "device-finder tool path")
	fs.StringVar(&c.SerialSocketPath, "device-serial", os.Getenv(constants.SerialSocketEnvKey), "device serial path")

	return c
}

func (c *DeviceConfig) DeviceResolver(ctx context.Context) (device.DeviceResolver, error) {
	if c.deviceHostname != "" {
		return device.NewConstantHostResolver(c.deviceName, c.deviceHostname), nil
	}

	return device.NewDeviceFinderResolver(ctx, c.deviceFinderPath, c.deviceName)
}

func (c *DeviceConfig) SSHPrivateKey() (ssh.Signer, error) {
	if c.sshPrivateKey == nil {
		if c.sshKeyFile == "" {
			return nil, fmt.Errorf("ssh private key cannot be empty")
		}

		key, err := ioutil.ReadFile(c.sshKeyFile)
		if err != nil {
			return nil, err
		}

		privateKey, err := ssh.ParsePrivateKey(key)
		if err != nil {
			return nil, err
		}
		c.sshPrivateKey = privateKey
	}

	return c.sshPrivateKey, nil
}

func (c *DeviceConfig) NewDeviceClient(ctx context.Context) (*device.Client, error) {
	deviceResolver, err := c.DeviceResolver(ctx)
	if err != nil {
		return nil, err
	}

	sshPrivateKey, err := c.SSHPrivateKey()
	if err != nil {
		return nil, err
	}

	return device.NewClient(ctx, deviceResolver, sshPrivateKey)
}