package service

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net"
	"os"
)

type UpdateRequest struct {
	IPv4     net.IP
	IPv6     net.IP
	UserName string
	Password string `json:"-"`
	IPv6Net  *net.IPNet
	Config   *UserConfig `json:"-"`
}

func (ur *UpdateRequest) String() string {
	return fmt.Sprintf("IPv4: %v, IPv6: %v, UserName: %v, Password: %v, IPv6Net: %v",
		ur.IPv4, ur.IPv6, ur.UserName, ur.Password, ur.IPv6Net)
}

func (ur *UpdateRequest) PrettyPrint() string {
	s, err := json.MarshalIndent(ur, "", " ")
	if err != nil {
		log.Fatalf("Failed to pretty print UpdateRequest via JSON: %v", err)
	}
	return string(s)
}

func (ur *UpdateRequest) MergeOldStateFile() {
	filename := ur.Config.GetStateFileName()

	if _, err := os.Stat(filename); err != nil {
		log.Printf("No old state file %s found, skip merging: %v", filename, err)
	}

	// We have a state file present, load it and merge into current state
	// so that we don't loose any IPv4/v6 data during partial updates.

	oldState, err := LoadStateFile(ur.Config)
	if err != nil {
		log.Printf("Failed to load old state file %s to merge while saving, skipping it: %v",
			filename, err)
		return
	}

	if ur.IPv4 == nil {
		ur.IPv4 = oldState.IPv4
	}
	if ur.IPv6 == nil {
		ur.IPv6 = oldState.IPv6
		ur.IPv6Net = oldState.IPv6Net
	}
}

func (ur *UpdateRequest) SaveStateFile() error {
	ur.MergeOldStateFile()

	filename := ur.Config.GetStateFileName()
	data, err := json.MarshalIndent(ur, "", " ")
	if err != nil {
		return fmt.Errorf("failed to convert state for user %s to JSON: %v",
			ur.UserName, err)
	}
	if err = ioutil.WriteFile(filename, data, 0640); err != nil {
		return fmt.Errorf("failed to to write sate file for user %s to file %s: %v",
			ur.UserName, filename, err)
	}
	return nil
}

func LoadStateFile(uc *UserConfig) (*UpdateRequest, error) {
	filename := uc.GetStateFileName()
	data, err := ioutil.ReadFile(filename)
	if err != nil {
		return nil, fmt.Errorf("failed to read state file %s for user %s, %v",
			uc.UserName, filename, err)
	}
	var ur UpdateRequest
	if err = json.Unmarshal(data, &ur); err != nil {
		return nil, fmt.Errorf("failed to unmarshal state JSON for user %s: %v",
			uc.UserName, err)
	}
	ur.Config = uc
	return &ur, nil
}

func (ur *UpdateRequest) Process() error {
	nfu := NewNFTUpdate()

	if err := DNSUpdateEntry(ur.Config.Domain, ur.Config.Router.Hostname, ur.IPv4, ur.IPv6); err != nil {
		return fmt.Errorf("failed to update router DNS: %v", err)
	}
	if ur.Config.Router.NFT.Table != "" {
		if ur.IPv4 != nil && ur.Config.Router.NFT.Set4 != "" {
			if err := nfu.AddIP(ur.Config.Router.NFT.Table, ur.Config.Router.NFT.Set4, ur.IPv4); err != nil {
				return fmt.Errorf("failed to update IPv4 Router NFT setup: %v", err)
			}
		}
		if ur.IPv6 != nil && ur.Config.Router.NFT.Set6 != "" {
			if err := nfu.AddIP(ur.Config.Router.NFT.Table, ur.Config.Router.NFT.Set6, ur.IPv6); err != nil {
				return fmt.Errorf("failed to update IPv6 Router NFT setup: %v", err)
			}
		}
	}

	for _, other := range ur.Config.Others {
		fullV6IP := other.ConvertIIDToAddress(ur.IPv6Net)
		if other.RegisterV4 {
			if err := DNSUpdateEntry(ur.Config.Domain, other.Hostname, ur.IPv4, fullV6IP); err != nil {
				return fmt.Errorf("failed to update DNS for host %s: %v", other.Hostname, err)
			}
		} else if ur.IPv6 != nil {
			if err := DNSUpdateEntry(ur.Config.Domain, other.Hostname, nil, fullV6IP); err != nil {
				return fmt.Errorf("failed to update DNS for host %s: %v", other.Hostname, err)
			}
		}

		if other.NFT.Table != "" {
			if other.NFT.Set6 != "" && ur.IPv6 != nil {
				if err := nfu.AddIP(other.NFT.Table, other.NFT.Set6, fullV6IP); err != nil {
					return fmt.Errorf("failed to update IPv6 NFT setup for host %s: %v", other.Hostname, err)
				}
			}
			if other.RegisterV4 && other.NFT.Set4 != "" && ur.IPv4 != nil {
				if err := nfu.AddIP(other.NFT.Table, other.NFT.Set4, ur.IPv4); err != nil {
					return fmt.Errorf("failed to update IPv6 NFT setup for host %s: %v", other.Hostname, err)
				}
			}
		}
	}

	log.Println("Summary of collected NFT Updates:")
	log.Println(nfu.PrettyPrint())

	if err := nfu.Process(); err != nil {
		return fmt.Errorf("failed to update NFT Setup: %v", err)
	}

	if err := ur.SaveStateFile(); err != nil {
		return fmt.Errorf("failed to save state file: %v", err)
	}

	return nil
}