package nft

import (
	"errors"
	"regexp"
	"strings"

	"git.kor-elf.net/kor-elf-shield/go-nftables-client/internal/chain"
	"git.kor-elf.net/kor-elf-shield/go-nftables-client/internal/command"
	"git.kor-elf.net/kor-elf-shield/go-nftables-client/internal/rule"
	"git.kor-elf.net/kor-elf-shield/go-nftables-client/internal/table"
)

// NFT A client for working with nftables
type NFT interface {
	// Command returns the command used to execute nft.
	// You can execute your raw request.
	Command() command.NFT

	// Clear clears all rules.
	//
	// This command is equivalent to:
	//    nft flush ruleset
	Clear() error

	// Version returns the version of nftables.
	//
	// This command is equivalent to:
	//    nft -V
	Version() (Version, error)

	// Table returns an API for working with tables.
	Table() table.API

	// Chain returns an API for working with chains.
	Chain() chain.API

	// Rule returns an API for working with rules.
	Rule() rule.API
}

type nft struct {
	command command.NFT
	table   table.API
	chain   chain.API
	rule    rule.API
}

// New Returns a client for working with nftables.
// Searches for nft in paths: nft, /usr/sbin/nft, /sbin/nft
func New() (NFT, error) {
	paths := []string{"nft", "/usr/sbin/nft", "/sbin/nft"}
	for _, path := range paths {
		nftClient, err := NewWithPath(path)
		if err == nil {
			return nftClient, nil
		}
	}

	return nil, errors.New("nft not found")
}

// NewWithPath Returns the client for working with nftables with its path specified.
func NewWithPath(path string) (NFT, error) {
	nftCommand, err := command.New(path)
	if err != nil {
		return nil, err
	}

	return &nft{
		command: nftCommand,
		table:   table.New(nftCommand),
		chain:   chain.New(nftCommand),
		rule:    rule.New(nftCommand),
	}, nil
}

func (n *nft) Clear() error {
	args := []string{"flush", "ruleset"}
	return n.command.Run(args...)
}

func (n *nft) Version() (Version, error) {
	args := []string{"-V"}
	out, err := n.command.RunWithOutput(args...)
	if err != nil {
		return nil, err
	}

	vers := ""
	opts := make(map[string]string)

	lines := regexp.MustCompile("\r?\n").Split(strings.TrimSpace(string(out)), -1)
	for index, line := range lines {
		line = strings.TrimSpace(line)

		if index == 0 {
			vers = line
			continue
		}

		values := strings.Split(line, ":")
		if len(values) != 2 {
			continue
		}
		name := strings.TrimSpace(values[0])
		value := strings.TrimSpace(values[1])
		opts[name] = value
	}

	return &version{
		version: vers,
		opts:    opts,
	}, nil
}

func (n *nft) Table() table.API {
	return n.table
}

func (n *nft) Chain() chain.API {
	return n.chain
}

func (n *nft) Rule() rule.API {
	return n.rule
}

func (n *nft) Command() command.NFT {
	return n.command
}