package main

import (
	"context"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/therootcompany/golib/net/dataset"
	"github.com/therootcompany/golib/net/gitshallow"
	"github.com/therootcompany/golib/net/httpcache"
	"github.com/therootcompany/golib/net/ipcohort"
)

const (
	inboundSingleURL   = "https://github.com/bitwire-it/ipblocklist/raw/refs/heads/main/tables/inbound/single_ips.txt"
	inboundNetworkURL  = "https://github.com/bitwire-it/ipblocklist/raw/refs/heads/main/tables/inbound/networks.txt"
	outboundSingleURL  = "https://github.com/bitwire-it/ipblocklist/raw/refs/heads/main/tables/outbound/single_ips.txt"
	outboundNetworkURL = "https://github.com/bitwire-it/ipblocklist/raw/refs/heads/main/tables/outbound/networks.txt"
)

func main() {
	dataDir   := flag.String("data-dir", "", "blacklist cache dir (default ~/.cache/bitwire-it)")
	gitURL    := flag.String("git", "", "git URL to clone/pull blacklist from")
	whitelist := flag.String("whitelist", "", "path to whitelist file")
	inbound   := flag.String("inbound", "", "comma-separated paths to inbound blacklist files")
	outbound  := flag.String("outbound", "", "comma-separated paths to outbound blacklist files")
	geoipConf := flag.String("geoip-conf", "", "path to GeoIP.conf (auto-discovered if absent)")
	cityDB    := flag.String("city-db", "", "path to GeoLite2-City.mmdb (skips auto-download)")
	asnDB     := flag.String("asn-db", "", "path to GeoLite2-ASN.mmdb (skips auto-download)")
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, "Usage: %s [flags] <ip-address>\n", os.Args[0])
		flag.PrintDefaults()
	}
	flag.Parse()

	if flag.NArg() != 1 {
		flag.Usage()
		os.Exit(1)
	}
	ipStr := flag.Arg(0)

	// -- Blacklist ----------------------------------------------------------

	var inboundDS, outboundDS *dataset.Dataset[ipcohort.Cohort]

	switch {
	case *inbound != "" || *outbound != "":
		inboundDS  = cohortDataset(dataset.NopSyncer{}, splitPaths(*inbound)...)
		outboundDS = cohortDataset(dataset.NopSyncer{}, splitPaths(*outbound)...)

	case *gitURL != "":
		dir := cacheDir(*dataDir, "bitwire-it")
		gr  := gitshallow.New(*gitURL, dir, 1, "")
		inSingle  := gr.File("tables/inbound/single_ips.txt")
		inNetwork := gr.File("tables/inbound/networks.txt")
		outSingle := gr.File("tables/outbound/single_ips.txt")
		outNetwork:= gr.File("tables/outbound/networks.txt")
		// Each File.Fetch deduplicates the git pull via the shared Repo.
		inboundDS  = cohortDataset(dataset.MultiSyncer{inSingle, inNetwork},  inSingle.Path(), inNetwork.Path())
		outboundDS = cohortDataset(dataset.MultiSyncer{outSingle, outNetwork}, outSingle.Path(), outNetwork.Path())

	default:
		dir := cacheDir(*dataDir, "bitwire-it")
		inSingle  := httpcache.New(inboundSingleURL,   filepath.Join(dir, "inbound_single_ips.txt"))
		inNetwork := httpcache.New(inboundNetworkURL,  filepath.Join(dir, "inbound_networks.txt"))
		outSingle := httpcache.New(outboundSingleURL,  filepath.Join(dir, "outbound_single_ips.txt"))
		outNetwork:= httpcache.New(outboundNetworkURL, filepath.Join(dir, "outbound_networks.txt"))
		inboundDS  = cohortDataset(dataset.MultiSyncer{inSingle, inNetwork},   inSingle.Path, inNetwork.Path)
		outboundDS = cohortDataset(dataset.MultiSyncer{outSingle, outNetwork}, outSingle.Path, outNetwork.Path)
	}

	var whitelistDS *dataset.Dataset[ipcohort.Cohort]
	if *whitelist != "" {
		whitelistDS = cohortDataset(dataset.NopSyncer{}, splitPaths(*whitelist)...)
	}

	for _, ds := range []*dataset.Dataset[ipcohort.Cohort]{whitelistDS, inboundDS, outboundDS} {
		if ds == nil {
			continue
		}
		if err := ds.Init(); err != nil {
			fmt.Fprintf(os.Stderr, "error: blacklist: %v\n", err)
			os.Exit(1)
		}
	}
	fmt.Fprintf(os.Stderr, "Loaded inbound=%d outbound=%d\n",
		inboundDS.Load().Size(), outboundDS.Load().Size())

	// -- GeoIP (optional) --------------------------------------------------

	geo, err := setupGeo(*geoipConf, *cityDB, *asnDB)
	if err != nil {
		fmt.Fprintf(os.Stderr, "error: %v\n", err)
		os.Exit(1)
	}
	if err := geo.Init(); err != nil {
		fmt.Fprintf(os.Stderr, "error: geoip: %v\n", err)
		os.Exit(1)
	}

	// -- Background refresh ------------------------------------------------

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	for _, ds := range []*dataset.Dataset[ipcohort.Cohort]{whitelistDS, inboundDS, outboundDS} {
		if ds != nil {
			go ds.Run(ctx, 47*time.Minute)
		}
	}
	geo.Run(ctx, 47*time.Minute)

	// -- Check and report --------------------------------------------------

	blockedIn  := isBlocked(ipStr, whitelistDS, inboundDS)
	blockedOut := isBlocked(ipStr, whitelistDS, outboundDS)

	switch {
	case blockedIn && blockedOut:
		fmt.Printf("%s is BLOCKED (inbound + outbound)\n", ipStr)
	case blockedIn:
		fmt.Printf("%s is BLOCKED (inbound)\n", ipStr)
	case blockedOut:
		fmt.Printf("%s is BLOCKED (outbound)\n", ipStr)
	default:
		fmt.Printf("%s is allowed\n", ipStr)
	}
	geo.PrintInfo(os.Stdout, ipStr)

	if blockedIn || blockedOut {
		os.Exit(1)
	}
}

// cohortDataset creates a Dataset that fetches via syncer and loads paths as a Cohort.
func cohortDataset(syncer dataset.Syncer, paths ...string) *dataset.Dataset[ipcohort.Cohort] {
	return dataset.New(syncer, func() (*ipcohort.Cohort, error) {
		return ipcohort.LoadFiles(paths...)
	})
}

func isBlocked(ip string, whitelist, cohort *dataset.Dataset[ipcohort.Cohort]) bool {
	if cohort == nil {
		return false
	}
	if whitelist != nil && whitelist.Load().Contains(ip) {
		return false
	}
	return cohort.Load().Contains(ip)
}

func cacheDir(override, sub string) string {
	if override != "" {
		return override
	}
	base, err := os.UserCacheDir()
	if err != nil {
		base = filepath.Join(os.Getenv("HOME"), ".cache")
	}
	return filepath.Join(base, sub)
}

func splitPaths(s string) []string {
	return strings.Split(s, ",")
}