package main

import (
	"errors"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"math"
	"os"
	"strconv"
	"strings"

	"git.sr.ht/~blallo/papero/cli"
	"git.sr.ht/~blallo/papero/imaputils"
	"github.com/emersion/go-imap"
)

const maxUInt32 = int(^uint32(0))

var infoVerbs cli.CommandMap

func init() {
	infoVerbs = cli.CommandMap{
		"list-mailboxes": LsMailboxCmd{},
		// "list-subscribed": LsSubscribedCmd{},
		"list-messages":   LsMsgCmd{},
		"display-message": CatMsgCmd{},
	}
}

type InfoCmd struct{}

func (i InfoCmd) Func(args []string) error {
	flagset := flag.NewFlagSet(args[0], flag.ExitOnError)
	flagset.Usage = func() { i.Help(os.Stdout, flagset) }
	flagset.Parse(args[1:])
	subArgs := flagset.Args()
	if len(subArgs) == 0 {
		i.Help(os.Stderr, flagset)
		os.Exit(1)
	}
	cmd := subArgs[0]
	if Session.Info.Opts.Debug {
		Log.Debug("info verb:", cmd)
	}

	return infoVerbs[cmd].Func(subArgs)
}

func (i InfoCmd) Help(w io.Writer, set *flag.FlagSet) {
	fmt.Fprintf(w, "USAGE: %s info VERB [verb opts]\n", Session.Info.Name)
	fmt.Fprintf(w, "\nVERBS:\n")
	for verb := range infoVerbs {
		fmt.Fprintf(w, "\t%s\n", verb)
	}
}

// VERBS

type LsMailboxCmd struct{}

type mailboxInfo struct {
	name  string
	attrs string
}

func (l LsMailboxCmd) Func(args []string) error {
	if Session.Info.Opts.Debug {
		Log.Debug("enter info list-mailboxes")
	}
	var withAttributes bool
	var output string
	var maxLen int
	var mailboxes []mailboxInfo
	flagset := flag.NewFlagSet(args[0], flag.ExitOnError)
	flagset.BoolVar(&withAttributes, "with-attrs", false, "toggle attributes display")
	flagset.Usage = func() { l.Help(os.Stdout, flagset) }
	flagset.Parse(args[1:])

	mboxInfo, err := imaputils.ListMailboxes(Session.Config, Session.Info.Opts.Debug)
	if err != nil {
		return err
	}
	if Session.Info.Opts.Debug {
		Log.Debug(mboxInfo)
	}
	for _, box := range mboxInfo {
		if withAttributes {
			if nameLen := len(box.Name); nameLen > maxLen {
				maxLen = nameLen
			}
			mailboxes = append(mailboxes, mailboxInfo{name: box.Name, attrs: fmt.Sprint(box.Attributes)})
		} else {
			output += fmt.Sprintln(box.Name)
		}
	}
	if maxLen == 0 {
		fmt.Print(output)
	} else {
		padFmtStr := fmt.Sprintf("%%-%dv\t", maxLen)
		for _, m := range mailboxes {
			line := fmt.Sprintf(padFmtStr, m.name)
			line += m.attrs
			fmt.Println(line)
		}
	}
	return nil
}

func (l LsMailboxCmd) Help(w io.Writer, set *flag.FlagSet) {
	fmt.Fprintf(w, "USAGE: %s info list-mailboxes [opts]\n", Session.Info.Name)
	fmt.Fprintf(w, "\nOPTS:\n")
	set.PrintDefaults()
}

type LsMsgCmd struct{}

func (l LsMsgCmd) Func(args []string) error {
	if Session.Info.Opts.Debug {
		Log.Debug("enter info list-messages")
	}
	var limit uint
	var withSeq, withFrom, withDate, withFlags bool
	var sep string
	flagset := flag.NewFlagSet(args[0], flag.ExitOnError)
	flagset.StringVar(&sep, "sep", "\t", "separator between fields")
	flagset.UintVar(&limit, "limit", 0, "maximum number of messages to display (0 means no limit)")
	flagset.BoolVar(&withSeq, "seq", false, "show sequence number")
	flagset.BoolVar(&withFrom, "from", false, "show From address")
	flagset.BoolVar(&withDate, "date", false, "show message date")
	flagset.BoolVar(&withFlags, "flags", false, "show message flags")
	flagset.Usage = func() { l.Help(os.Stdout, flagset) }
	flagset.Parse(args[1:])

	subArgs := flagset.Args()
	if len(subArgs) != 1 {
		l.Help(os.Stderr, flagset)
		os.Exit(1)
	}

	msgs, err := imaputils.ListMessages(
		Session.Config,
		&imaputils.ListMessagesOpts{
			Mailbox: subArgs[0],
			Limit:   uint32(limit),
		},
		Session.Info.Opts.Debug,
	)
	if err != nil {
		return err
	}
	printMsgs(msgs, withSeq, withFrom, withDate, withFlags, sep)
	return nil
}

func (l LsMsgCmd) Help(w io.Writer, set *flag.FlagSet) {
	fmt.Fprintf(w, "USAGE: %s info list-messages [opts] MAILBOX_NAME\n", Session.Info.Name)
	fmt.Fprintf(w, "\nOPTS:\n")
	set.PrintDefaults()
}

func numberSize(n uint32) int {
	return int(math.Floor(math.Log10(float64(n))))
}

func printMsgs(msgs []*imap.Message, withSeq, withFrom, withDate, withFlags bool, sep string) {
	var maxSeq, maxDateLen, maxFromLen, maxFlagsLen int
	var out, seqFmtStr, dateFmtStr, fromFmtStr, flagsFmtStr string
	for _, msg := range msgs {
		if seqSize := numberSize(msg.SeqNum); withSeq && seqSize > maxSeq {
			maxSeq = seqSize
		}
		if withDate {
			date := fmt.Sprint(msg.Envelope.Date)
			if dateLen := len(date); dateLen > maxDateLen {
				maxDateLen = dateLen
			}
		}
		if withFrom {
			for _, from := range msg.Envelope.From {
				if fromLen := len(from.Address()); fromLen > maxFromLen {
					maxFromLen = fromLen
				}
			}
		}
		if withFlags {
			var flags string
			for _, f := range msg.Flags {
				flags += fmt.Sprintf("%s ", f)
			}
			flags = strings.TrimRight(flags, " ")
			if flagsLen := len(flags); flagsLen > maxFlagsLen {
				maxFlagsLen = flagsLen
			}
		}
	}

	if withSeq {
		seqFmtStr = fmt.Sprintf("%%%dv%s", maxSeq, sep)
	}
	if withDate {
		dateFmtStr = fmt.Sprintf("%%-%dv%s", maxDateLen, sep)
	}
	if withFrom {
		fromFmtStr = fmt.Sprintf("%%-%dv%s", maxFromLen, sep)
	}
	if withFlags {
		flagsFmtStr = fmt.Sprintf("%%-%dv%s", maxFlagsLen, sep)
	}
	for _, msg := range msgs {
		var line string
		if withSeq {
			line += fmt.Sprintf(seqFmtStr, msg.SeqNum)
		}
		if withDate {
			line += fmt.Sprintf(dateFmtStr, msg.Envelope.Date)
		}
		if withFrom {
			line += fmt.Sprintf(fromFmtStr, msg.Envelope.From[0].Address())
		}
		if withFlags {
			var flags string
			for _, f := range msg.Flags {
				flags += fmt.Sprintf("%s ", f)
			}
			line += fmt.Sprintf(flagsFmtStr, strings.TrimRight(flags, " "))
		}
		line += msg.Envelope.Subject
		out += fmt.Sprintln(line)
	}
	fmt.Println(out)
}

type CatMsgCmd struct{}

func (c CatMsgCmd) Func(args []string) error {
	if Session.Info.Opts.Debug {
		Log.Debug("enter info display-message")
	}
	var idList []uint32
	var withHeaders, withBody, withFlags, markRead bool
	flagset := flag.NewFlagSet(args[0], flag.ExitOnError)
	flagset.BoolVar(&withHeaders, "headers", false, "toggle headers display")
	flagset.BoolVar(&withBody, "no-body", false, "hide body")
	flagset.BoolVar(&withFlags, "flags", false, "show flags")
	flagset.BoolVar(&markRead, "seen", false, "mark as seen if not yet seen")
	flagset.Usage = func() { c.Help(os.Stdout, flagset) }
	flagset.Parse(args[1:])

	subArgs := flagset.Args()
	lenSubArgs := len(subArgs)
	if lenSubArgs < 2 {
		c.Help(os.Stderr, flagset)
		os.Exit(1)
	}

	mailbox := subArgs[0]

	if lenSubArgs > 1 {
		for _, id := range subArgs[1:] {
			mailId, err := parseToUint32(id)
			if err != nil {
				return err
			}
			idList = append(idList, mailId)
		}
	}

	opts := &imaputils.FetchOpts{
		Mailbox:     mailbox,
		IdList:      idList,
		WithHeaders: withHeaders,
		WithBody:    !withBody,
		WithFlags:   withFlags,
		Peek:        !markRead,
	}
	if Session.Info.Opts.Debug {
		Log.Debug(opts)
	}

	messages, err := imaputils.FetchMessages(Session.Config, opts, Session.Info.Opts.Debug)
	if err != nil {
		return err
	}

	for _, m := range messages {
		err = printMessage(m, opts, withFlags)
		if err != nil {
			return err
		}
	}
	return nil
}

func (c CatMsgCmd) Help(w io.Writer, set *flag.FlagSet) {
	fmt.Fprintf(w, "USAGE: %s info display-message [opts] MAILBOX_NAME [MESSAGE_ID1 [MESSAGE_ID2 [...]]]\n", Session.Info.Name)
	fmt.Fprintf(w, "\nOPTS:\n")
	set.PrintDefaults()
}

var ErrOutOfBounds = errors.New("number is out of bounds")

func parseToUint32(s string) (uint32, error) {
	out, err := strconv.Atoi(s)
	if err != nil {
		return 0, err
	}

	if out < 0 || out > maxUInt32 {
		return 0, ErrOutOfBounds
	}

	return uint32(out), nil
}

func printMessage(m *imap.Message, opts *imaputils.FetchOpts, withFlags bool) error {
	var out string

	if withFlags {
		if Session.Info.Opts.Debug {
			Log.Debug(m.Flags)
		}
		for _, f := range m.Flags {
			out += fmt.Sprintf("%s ", f)
		}
		out = strings.TrimRight(out, " ")
		out += "\n"
	}

	if opts.WithHeaders {
		out += fmt.Sprintln(formatAddresses(m.Envelope.From, "From"))
		out += fmt.Sprintln(formatAddresses(m.Envelope.Sender, "Sender"))
		out += fmt.Sprintln(formatAddresses(m.Envelope.Cc, "Cc"))
		out += fmt.Sprintln(formatAddresses(m.Envelope.Bcc, "Bcc"))
		out += fmt.Sprintln(formatAddresses(m.Envelope.ReplyTo, "ReplyTo"))
		out += fmt.Sprintf("InReplyTo: %s\n", m.Envelope.InReplyTo)
		out += fmt.Sprintf("Date: %v\n", m.Envelope.Date)
		out += fmt.Sprintf("Subject: %s\n", m.Envelope.Subject)

		headersSec := &imap.BodySectionName{Peek: opts.Peek, BodyPartName: imap.BodyPartName{Specifier: imap.HeaderSpecifier}}
		headersReader := m.GetBody(headersSec)
		headers, err := ioutil.ReadAll(headersReader)
		if err != nil {
			return err
		}
		out += fmt.Sprintln(string(headers))
	}

	if opts.WithBody {
		bodySec := &imap.BodySectionName{Peek: opts.Peek, BodyPartName: imap.BodyPartName{Specifier: imap.TextSpecifier}}
		bodyReader := m.GetBody(bodySec)
		body, err := ioutil.ReadAll(bodyReader)
		if err != nil {
			return err
		}
		out += fmt.Sprintln(string(body))
	}

	fmt.Println(out)
	return nil
}

func formatAddresses(addresses []*imap.Address, name string) string {
	out := fmt.Sprintf("%s: ", name)
	for _, address := range addresses {
		if address.PersonalName != "" {
			out += fmt.Sprintf("%s <%s>, ", address.PersonalName, address.Address())
		} else {
			out += fmt.Sprintf("%s, ", address.Address())
		}
	}
	return strings.TrimRight(out, ", ")
}