package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"regexp"

	"golang.org/x/crypto/ssh"
)

type Config struct {
	Zfsnap   map[string]string     `json:"zfsnap"`
	Box      map[string]*BoxConfig `json:"box"`
	Apps     []AppConfig           `json:apps`
	Timezone string                `json:"timezone"`
}

type BoxConfig struct {
	Addr string `json:"addr"`
	User string `json:"user"`
	Key  string `json:"key"`
	ssh  *SSHConfig
}

var (
	cfgFile   = flag.String("config", "config.json", "config file")
	schedFlag = flag.String("schedule", "", "specific schedule")
	testFlag  = flag.Bool("test", true, "test run")
	debugFlag = flag.Bool("debug", true, "debug")
	cfg       Config
)

//Load config from file
func (c *Config) Load() error {
	if *debugFlag {
		log.Printf("SSHConfig.Load : Start")
	}
	b, err := ioutil.ReadFile(*cfgFile)
	if err != nil {
		if *debugFlag {
			log.Printf("Config.Load : ioutil.ReadFile(%s) : %s", *cfgFile, err)
		}
		return err
	}

	err = json.Unmarshal(b, &c)
	if err != nil {
		if *debugFlag {
			log.Printf("Config.Load : json.Unmarshal : %s", err)
		}
		return err
	}

	for k, v := range c.Box {
		s := &SSHConfig{
			logged: false,
			name:   k,
		}
		v.ssh = s
		keyRaw, err := ioutil.ReadFile(v.Key)
		if err != nil {
			if *debugFlag {
				log.Printf("Config.Load : ioutil.ReadFile(%s) : %s", k, err)
			}
			return err
		}

		key, err := ssh.ParseRawPrivateKey(keyRaw)
		if err != nil {
			if *debugFlag {
				log.Printf("Config.Load : ssh.ParseRawPrivateKey(%s) : %s", k, err)
			}
			return err
		}

		s.signer, err = ssh.NewSignerFromKey(key)
		if err != nil {
			if *debugFlag {
				log.Printf("Config.Load : ssh.NewSignerFromKey(%s) : %s", k, err)
			}
			return err
		}

		s.config = &ssh.ClientConfig{
			User: v.User,
			Auth: []ssh.AuthMethod{
				ssh.PublicKeys(s.signer),
			},
			HostKeyCallback: ssh.InsecureIgnoreHostKey(),
		}

		s.client, err = ssh.Dial("tcp", v.Addr, s.config)
		if err != nil {
			if *debugFlag {
				log.Printf("Config.Load : ssh.Dial(%s) : %s", k, err)
			}
			return err
		}

		session, err := s.client.NewSession()
		if err != nil {
			if *debugFlag {
				log.Printf("Config.Load : client.NewSession(%s) : %s", k, err)
			}
			return err
		}

		var b bytes.Buffer
		session.Stdout = &b

		err = session.Run("TZ=\"" + cfg.Timezone + "\" /usr/sbin/zfsnap --version")
		if err != nil {
			if *debugFlag {
				log.Printf("Config.Load : client.NewSession(%s) : %s", k, err)
			}
			return err
		}
		if *debugFlag {
			log.Printf("Config.Load : logged into %s : %s", k, b.String())
		}
		session.Close()
		s.logged = true
	}

	for _, box := range c.Box {
		err = box.ssh.getTime()
		if err != nil {
			if *debugFlag {
				log.Printf("Config.Load : ssh.getTime() : %s", err)
			}
			return err
		}
	}

	for _, app := range c.Apps {
		for _, src := range app.Sources {
			if !src.Valid() {
				return fmt.Errorf("Source not valid : %s", string(src))
			}
			if _, ok := cfg.Box[src.Box()]; !ok {
				return fmt.Errorf("No box defined for source : %s", string(src))
			}
		}
		for _, dest := range app.Destinations {
			if !dest.Valid() {
				return fmt.Errorf("Destination not valid : %s", string(dest))
			}
			if _, ok := cfg.Box[dest.Box()]; !ok {
				return fmt.Errorf("No box defined for destination : %s", string(dest))
			}
		}
		for val, before := range app.Before {
			_, err = regexp.Compile(val)
			if err != nil {
				if *debugFlag {
					log.Printf("Config.Load : invalid regex : %s", val)
				}
				return err
			}
			if !before.Valid() {
				return fmt.Errorf("Before not valid : %s", string(before))
			}
			if _, ok := cfg.Box[before.Box()]; !ok {
				return fmt.Errorf("No box defined for before : %s", string(before))
			}
		}
		for val, after := range app.After {
			_, err = regexp.Compile(val)
			if err != nil {
				if *debugFlag {
					log.Printf("Config.Load : invalid regex : %s", val)
				}
				return err
			}
			if !after.Valid() {
				return fmt.Errorf("After not valid : %s", string(after))
			}
			if _, ok := cfg.Box[after.Box()]; !ok {
				return fmt.Errorf("No box defined for after : %s", string(after))
			}
		}
	}

	return nil
}

//Close config
func (c *Config) Close() error {
	return nil
}

func main() {
	flag.Parse()

	err := cfg.Load()
	if err != nil {
		log.Printf("Cannot load config (%s)", err)
		os.Exit(1)
	}

	err = RunBackup()
	if err != nil {
		log.Printf("Cannot run schedule (%s)", err)
		os.Exit(1)
	}
}

//RunBackup run all backup targets where schedule is registered
func RunBackup() error {
	if *debugFlag {
		log.Printf("RunBackup() : Start")
	}

	for _, app := range cfg.Apps {
		err := app.RunAppBackup()
		if err != nil {
			if *debugFlag {
				log.Printf("RunBackup() : Error running %s", app.Name)
			}
			return err
		}
	}

	return nil
}