package main

import (
	"bytes"
	"fmt"
	"log"
	"net/netip"
	"strconv"
	"strings"

	"github.com/olekukonko/tablewriter"
	"github.com/olekukonko/tablewriter/tw"
)

const (
	sectBordChar string = "#"
	sectBordWdth int    = 2
	sectSpcPad   int    = 1

	sectSidePad int = sectBordWdth + sectSpcPad
	sectBothPad int = sectSidePad * 2
)

type (
	IpInfo struct {
		// Desc                      string
		Index int
		// IP                        netip.Addr
		Is4                       bool
		Is4In6                    bool
		Is6                       bool
		IsGlobalUnicast           bool
		IsLinkLocalUnicast        bool
		IsInterfaceLocalMulticast bool
		IsLinkLocalMulticast      bool
		IsMulticast               bool
		IsLoopback                bool
		IsPrivate                 bool
		IsUnspecified             bool
		IsValid                   bool
	}
)

var (
	datHdrsFunc []string = []string{
		"-",
		".Is4", ".Is4In6()", ".Is6()",
		".IsGlobalUnicast()", ".IsLinkLocalUnicast()",
		".IsInterfaceLocalMulticast()", ".IsLinkLocalMulticast()", ".IsMulticast()",
		".IsLoopback()",
		".IsPrivate()",
		".IsUnspecified()", ".IsValid()",
	}

	datHdrsKey []string = []string{
		"Address Index (See Fig. 3)",
		"IPv4", "4-in-6", "IPv6",
		"Global Unicast", "Link-Local Unicast",
		"Interface Local Multicast", "Link-Local Multicast", "Multicast",
		"Loopback",
		"Private/LAN",
		"\"Unspecified\" Address", "Valid Address",
	}

	datHdrsShort = []string{
		"IDX",
		"4", "6(4)", "6",
		"GU", "LLU",
		"ILM", "LLM", "M",
		"LO",
		"P",
		"U", "V",
	}

	exampleAddrs [][2]string = [][2]string{
		[2]string{"IPv4", "203.0.113.10"},                                                                           // RFC 5737 address (https://datatracker.ietf.org/doc/html/rfc5737)
		[2]string{"IPv4 Unspecified", "0.0.0.0"},                                                                    // Generally used to represent all of IPv4 address space
		[2]string{"IPv4 Global Unicast", "173.230.132.76"},                                                          // r00t2.io
		[2]string{"IPv4 Multicast (All) (RFC 1112 § 4)", "224.0.0.1"},                                               // Should encompass all the multicast below. 224.0.0.0 is reserved.
		[2]string{"IPv4 Multicast (Reserved) (RFC 1112 § 4)", "224.0.0.0"},                                          // Reserved per RFC but it should still report multicast.
		[2]string{"IPv4 Multicast (Link-Local Multicast/Local Network Control Block) (RFC 5771 § 4)", "224.0.0.18"}, // https://datatracker.ietf.org/doc/html/rfc5771#section-4 (VRRP multicast addr)
		[2]string{"IPv4 Multicast (Internetwork Control Block) (RFC 5771 § 5)", "224.0.1.68"},                       // https://datatracker.ietf.org/doc/html/rfc5771#section-5 (mdhcpdiscover, RFC 2730)
		[2]string{"IPv4 Multicast (AD-HOC I) (RFC 5771 § 6)", "224.0.2.10"},                                         // https://datatracker.ietf.org/doc/html/rfc5771#section-6
		[2]string{"IPv4 Multicast (SDP/SAP) (RFC 5771 § 7)", "224.2.0.10"},                                          // https://datatracker.ietf.org/doc/html/rfc5771#section-7
		[2]string{"IPv4 Multicast (AD-HOC II) (RFC 5771 § 6)", "224.3.0.10"},                                        // (above)
		[2]string{"IPv4 Multicast (Source-Specific) (RFC 5771 § 8)", "232.0.0.10"},                                  // https://datatracker.ietf.org/doc/html/rfc5771#section-8
		[2]string{"IPv4 Multicast (GLOP) (RFC 5771 § 9)", "233.0.0.10"},                                             // https://datatracker.ietf.org/doc/html/rfc5771#section-9
		[2]string{"IPv4 Multicast (AD-HOC III) (RFC 5771 § 6)", "233.252.0.10"},                                     // (above)
		[2]string{"IPv4 Multicast (Administrative) (RFC 5771 § 10)", "239.0.0.10"},                                  // https://datatracker.ietf.org/doc/html/rfc5771#section-10
		[2]string{"IPv4 Link-Local Unicast (RFC 3927 § 2.1)", "169.254.1.10"},                                       // https://datatracker.ietf.org/doc/html/rfc3927#section-2.1
		[2]string{"IPv4 Loopback", "127.0.1.10"},                                                                    // It's actually 127/8. Cannot believe how many people do not know this.
		[2]string{"IPv4 Private (RFC 1918)", "10.0.0.10"},                                                           // https://datatracker.ietf.org/doc/html/rfc1918
		[2]string{"4-in-6 (RFC 4291 § 2.5.5.1)", "::203.0.113.10"},                                                  // https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.5.1
		[2]string{"4-in-6 (RFC 4291 § 2.5.5.1) (Native)", "::cb00:710a"},                                            // ""
		[2]string{"4-in-6 (RFC 4291 § 2.5.5.2)", "::ffff:203.0.113.10"},                                             // https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.5.2
		[2]string{"4-in-6 (RFC 4291 § 2.5.5.2) (Native)", "::ffff:cb00:710a"},                                       // ""
		[2]string{"IPv6", "2001:db8::cb00:710a"},                                                                    // RFC 3849 (https://datatracker.ietf.org/doc/html/rfc3849) / RFC 9637 (https://datatracker.ietf.org/doc/html/rfc9637) address
		[2]string{"IPv6 Unspecified", "::"},                                                                         // Generally used to represent all of IPv6 address space
		[2]string{"IPv6 Global Unicast", "2600:3c02::f03c:91ff:fe93:c0a7"},                                          // r00t2.io
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (Reserved Net)", "ff00::"},                                     // https://datatracker.ietf.org/doc/html/rfc4291#section-2.7.1
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (Reserved)", "ff00::1"},                                        // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Nodes) (Interface-Local)", "ff01::1"},                     // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Nodes) (Link-Local)", "ff02::1"},                          // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Routers) (Interface-Local)", "ff01::2"},                   // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Routers) (Link-Local)", "ff02::2"},                        // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Routers) (Admin-Local)", "ff04::2"},                       // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Routers) (Site-Local)", "ff05::2"},                        // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Routers) (Org-Local)", "ff08::2"},                         // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (All Routers) (Internet/Global)", "ff0e::2"},                   // ""
		[2]string{"IPv6 Multicast (RFC 4291 § 2.7.1) (Solicited Node)", "ff02::1:ff00:10"},                          // ""
		[2]string{"IPv6 Link-Local Unicast (RFC 4291 § 2.5.6)", "fe80::cb00:710a"},                                  // https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.6
		[2]string{"IPv6 Loopback", "::1"},                                                                           // It's explicitly always a /128 with the address ::1 per RFC 4291 § 2.5.3.
		[2]string{"IPv6 Private (Unique-Local Addresses) (RFC 4193) (Reserved)", "fc00::10"},                        // https://datatracker.ietf.org/doc/html/rfc4193
		[2]string{"IPv6 Private (Unique-Local Addresses) (RFC 4193) (Valid)", "fd00::10"},                           // ""
	}

	descs []string     = make([]string, len(exampleAddrs))
	ips   []netip.Addr = make([]netip.Addr, len(exampleAddrs))

	sectSep string = "\n" + strings.Repeat("-", 80) + "\n"
)

func genHdr(sectNm string) (s string) {

	// Wish I finished stringsx.Banner at time of writing this...
	var fillLen int = sectBothPad + len(sectNm)

	s = fmt.Sprintf(
		"%s\n"+ // top border
			// begin title line
			"%-*s"+ // left-justify/right-pad
			"%s"+ // sectNm text
			"%[2]*[3]s\n"+ // one-indexed; repeat pad num and pad str from left border as right border
			// end title line
			"%[1]s\n",                                           // bottom border
		strings.Repeat(sectBordChar, fillLen),                   // top and bottom (bottom uses index)
		sectSidePad, strings.Repeat(sectBordChar, sectBordWdth), // title left and right borders (right uses index)
		sectNm, // title text
	)

	return
}

func main() {

	var err error
	var idx int
	var s string
	var desc string
	var pair [2]string
	var buf *bytes.Buffer = new(bytes.Buffer)

	var tbl *tablewriter.Table = tablewriter.NewTable(
		buf,
		tablewriter.WithConfig(
			tablewriter.Config{
				Header: tw.CellConfig{
					Formatting: tw.CellFormatting{
						AutoFormat: tw.Off,
					},
				},
			},
		),
		// requires .Batch(), and the autoheader forces all caps.
		// https://github.com/olekukonko/tablewriter/issues/143
		// https://github.com/olekukonko/tablewriter/issues/190
		/*
			tablewriter.WithBehavior(
				tw.Behavior{
					Structs: tw.Struct{
						AutoHeader: tw.On,
					},
				},
			),
		*/
		tablewriter.WithRendition(
			tw.Rendition{
				Settings: tw.Settings{
					Separators: tw.Separators{BetweenRows: tw.On},
				},
			},
		),
	)

	defer func() {
		var tErr error
		if tbl != nil {
			if tErr = tbl.Close(); tErr != nil {
				log.Printf("Error closing table: %v", tErr)
			}
		}
	}()

	buf.WriteString(genHdr("Fig. 1: Address Evaluations"))
	buf.WriteString("(See Fig. 2 for a key of header symbols to names)\n\n")

	tbl.Header(datHdrsShort)
	for idx, pair = range exampleAddrs {
		desc, s = pair[0], pair[1]
		descs[idx] = desc
		if ips[idx], err = netip.ParseAddr(s); err != nil {
			log.Panicln(err)
		}
		// Currently no way to skip cols etc. https://github.com/olekukonko/tablewriter/issues/317
		// rows[idx] = IpInfo{
		if err = tbl.Append(
			IpInfo{
				// Desc:                      desc,
				Index: idx,
				// IP:                        ip,
				Is4:                       ips[idx].Is4(),
				Is4In6:                    ips[idx].Is4In6(),
				Is6:                       ips[idx].Is6(),
				IsGlobalUnicast:           ips[idx].IsGlobalUnicast(),
				IsLinkLocalUnicast:        ips[idx].IsLinkLocalUnicast(),
				IsInterfaceLocalMulticast: ips[idx].IsInterfaceLocalMulticast(),
				IsLinkLocalMulticast:      ips[idx].IsLinkLocalMulticast(),
				IsMulticast:               ips[idx].IsMulticast(),
				IsLoopback:                ips[idx].IsLoopback(),
				IsPrivate:                 ips[idx].IsPrivate(),
				IsUnspecified:             ips[idx].IsUnspecified(),
				IsValid:                   ips[idx].IsValid(),
			},
		); err != nil {
			log.Panicln(err)
		}
	}
	/*
		if err = tbl.Bulk(rows); err != nil {
			log.Panicln(err)
		}
	*/
	if err = tbl.Render(); err != nil {
		log.Panicln(err)
	}

	buf.WriteString(sectSep)
	buf.WriteString(genHdr("Fig. 2: Headers Key for Fig. 1"))
	tbl.Reset()
	tbl.Header("Symbol", "Description", "net/netip.Addr Method")
	for idx = range datHdrsKey {
		if err = tbl.Append(
			[]string{
				datHdrsShort[idx],
				datHdrsKey[idx],
				datHdrsFunc[idx],
			},
		); err != nil {
			log.Panicln(err)
		}
	}
	if err = tbl.Render(); err != nil {
		log.Panicln(err)
	}

	buf.WriteString(sectSep)
	buf.WriteString(genHdr("Fig. 3: Test/Example IP Address Reference/Lookup for Fig. 1"))
	buf.WriteString("(See Fig. 4 for Descriptions/Detailed Information)\n\n")
	tbl.Reset()
	tbl.Header("Index", "Address (Raw)", "Address (Parsed)")
	for idx = range exampleAddrs {
		if err = tbl.Append(
			[]string{
				strconv.Itoa(idx),
				exampleAddrs[idx][1],
				ips[idx].String(),
			},
		); err != nil {
			log.Panicln(err)
		}
	}
	if err = tbl.Render(); err != nil {
		log.Panicln(err)
	}

	buf.WriteString(sectSep)
	buf.WriteString(genHdr("Fig. 4: Extended Information for Fig. 3"))
	tbl.Reset()
	tbl.Header("Index", "Description")
	for idx = range exampleAddrs {
		if err = tbl.Append(
			[]string{
				strconv.Itoa(idx),
				descs[idx],
			},
		); err != nil {
			log.Panicln(err)
		}
	}
	if err = tbl.Render(); err != nil {
		log.Panicln(err)
	}

	fmt.Println(buf.String())
}