/*
   Copyright 2014 CoreOS, Inc.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package initialize

import (
	"errors"
	"fmt"
	"log"
	"path"

	"github.com/coreos/coreos-cloudinit/config"
	"github.com/coreos/coreos-cloudinit/network"
	"github.com/coreos/coreos-cloudinit/system"
)

// CloudConfigFile represents a CoreOS specific configuration option that can generate
// an associated system.File to be written to disk
type CloudConfigFile interface {
	// File should either return (*system.File, error), or (nil, nil) if nothing
	// needs to be done for this configuration option.
	File() (*system.File, error)
}

// CloudConfigUnit represents a CoreOS specific configuration option that can generate
// associated system.Units to be created/enabled appropriately
type CloudConfigUnit interface {
	Units() []system.Unit
}

// Apply renders a CloudConfig to an Environment. This can involve things like
// configuring the hostname, adding new users, writing various configuration
// files to disk, and manipulating systemd services.
func Apply(cfg config.CloudConfig, env *Environment) error {
	if cfg.Hostname != "" {
		if err := system.SetHostname(cfg.Hostname); err != nil {
			return err
		}
		log.Printf("Set hostname to %s", cfg.Hostname)
	}

	for _, user := range cfg.Users {
		if user.Name == "" {
			log.Printf("User object has no 'name' field, skipping")
			continue
		}

		if system.UserExists(&user) {
			log.Printf("User '%s' exists, ignoring creation-time fields", user.Name)
			if user.PasswordHash != "" {
				log.Printf("Setting '%s' user's password", user.Name)
				if err := system.SetUserPassword(user.Name, user.PasswordHash); err != nil {
					log.Printf("Failed setting '%s' user's password: %v", user.Name, err)
					return err
				}
			}
		} else {
			log.Printf("Creating user '%s'", user.Name)
			if err := system.CreateUser(&user); err != nil {
				log.Printf("Failed creating user '%s': %v", user.Name, err)
				return err
			}
		}

		if len(user.SSHAuthorizedKeys) > 0 {
			log.Printf("Authorizing %d SSH keys for user '%s'", len(user.SSHAuthorizedKeys), user.Name)
			if err := system.AuthorizeSSHKeys(user.Name, env.SSHKeyName(), user.SSHAuthorizedKeys); err != nil {
				return err
			}
		}
		if user.SSHImportGithubUser != "" {
			log.Printf("Authorizing github user %s SSH keys for CoreOS user '%s'", user.SSHImportGithubUser, user.Name)
			if err := SSHImportGithubUser(user.Name, user.SSHImportGithubUser); err != nil {
				return err
			}
		}
		if user.SSHImportURL != "" {
			log.Printf("Authorizing SSH keys for CoreOS user '%s' from '%s'", user.Name, user.SSHImportURL)
			if err := SSHImportKeysFromURL(user.Name, user.SSHImportURL); err != nil {
				return err
			}
		}
	}

	if len(cfg.SSHAuthorizedKeys) > 0 {
		err := system.AuthorizeSSHKeys("core", env.SSHKeyName(), cfg.SSHAuthorizedKeys)
		if err == nil {
			log.Printf("Authorized SSH keys for core user")
		} else {
			return err
		}
	}

	var writeFiles []system.File
	for _, file := range cfg.WriteFiles {
		writeFiles = append(writeFiles, system.File{file})
	}

	for _, ccf := range []CloudConfigFile{
		system.OEM{cfg.Coreos.OEM},
		system.Update{cfg.Coreos.Update, system.DefaultReadConfig},
		system.EtcHosts{cfg.ManageEtcHosts},
	} {
		f, err := ccf.File()
		if err != nil {
			return err
		}
		if f != nil {
			writeFiles = append(writeFiles, *f)
		}
	}

	var units []system.Unit
	for _, u := range cfg.Coreos.Units {
		units = append(units, system.Unit{u})
	}

	for _, ccu := range []CloudConfigUnit{
		system.Etcd{cfg.Coreos.Etcd},
		system.Fleet{cfg.Coreos.Fleet},
		system.Update{cfg.Coreos.Update, system.DefaultReadConfig},
	} {
		units = append(units, ccu.Units()...)
	}

	wroteEnvironment := false
	for _, file := range writeFiles {
		fullPath, err := system.WriteFile(&file, env.Root())
		if err != nil {
			return err
		}
		if path.Clean(file.Path) == "/etc/environment" {
			wroteEnvironment = true
		}
		log.Printf("Wrote file %s to filesystem", fullPath)
	}

	if !wroteEnvironment {
		ef := env.DefaultEnvironmentFile()
		if ef != nil {
			err := system.WriteEnvFile(ef, env.Root())
			if err != nil {
				return err
			}
			log.Printf("Updated /etc/environment")
		}
	}

	if env.NetconfType() != "" {
		var interfaces []network.InterfaceGenerator
		var err error
		switch env.NetconfType() {
		case "debian":
			interfaces, err = network.ProcessDebianNetconf(cfg.NetworkConfig)
		case "digitalocean":
			interfaces, err = network.ProcessDigitalOceanNetconf(cfg.NetworkConfig)
		default:
			return fmt.Errorf("Unsupported network config format %q", env.NetconfType())
		}

		if err != nil {
			return err
		}

		if err := system.WriteNetworkdConfigs(interfaces); err != nil {
			return err
		}
		if err := system.RestartNetwork(interfaces); err != nil {
			return err
		}
	}

	um := system.NewUnitManager(env.Root())
	return processUnits(units, env.Root(), um)

}

// processUnits takes a set of Units and applies them to the given root using
// the given UnitManager. This can involve things like writing unit files to
// disk, masking/unmasking units, or invoking systemd
// commands against units. It returns any error encountered.
func processUnits(units []system.Unit, root string, um system.UnitManager) error {
	type action struct {
		unit    string
		command string
	}
	actions := make([]action, 0, len(units))
	reload := false
	for _, unit := range units {
		dst := unit.Destination(root)
		if unit.Content != "" {
			log.Printf("Writing unit %s to filesystem at path %s", unit.Name, dst)
			if err := um.PlaceUnit(&unit, dst); err != nil {
				return err
			}
			log.Printf("Placed unit %s at %s", unit.Name, dst)
			reload = true
		}

		if unit.Mask {
			log.Printf("Masking unit file %s", unit.Name)
			if err := um.MaskUnit(&unit); err != nil {
				return err
			}
		} else if unit.Runtime {
			log.Printf("Ensuring runtime unit file %s is unmasked", unit.Name)
			if err := um.UnmaskUnit(&unit); err != nil {
				return err
			}
		}

		if unit.Enable {
			if unit.Group() != "network" {
				log.Printf("Enabling unit file %s", unit.Name)
				if err := um.EnableUnitFile(unit.Name, unit.Runtime); err != nil {
					return err
				}
				log.Printf("Enabled unit %s", unit.Name)
			} else {
				log.Printf("Skipping enable for network-like unit %s", unit.Name)
			}
		}

		if unit.Group() == "network" {
			actions = append(actions, action{"systemd-networkd.service", "restart"})
		} else if unit.Command != "" {
			actions = append(actions, action{unit.Name, unit.Command})
		}
	}

	if reload {
		if err := um.DaemonReload(); err != nil {
			return errors.New(fmt.Sprintf("failed systemd daemon-reload: %v", err))
		}
	}

	for _, action := range actions {
		log.Printf("Calling unit command '%s %s'", action.command, action.unit)
		res, err := um.RunUnitCommand(action.command, action.unit)
		if err != nil {
			return err
		}
		log.Printf("Result of '%s %s': %s", action.command, action.unit, res)
	}

	return nil
}