package imaputils

import (
	"fmt"

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

func ListMailboxes(conf *config.AccountData, debug bool) ([]*imap.MailboxInfo, error) {
	var mailboxes []*imap.MailboxInfo
	conn := NewConnection(conf)

	err := conn.Start(debug)
	if err != nil {
		return mailboxes, err
	}
	defer conn.Close()

	mboxChan := make(chan *imap.MailboxInfo, 10)
	done := make(chan error, 1)
	go func() {
		done <- conn.client.List("", "*", mboxChan)
	}()

	for m := range mboxChan {
		mailboxes = append(mailboxes, m)
	}

	if err := <-done; err != nil {
		return mailboxes, err
	}

	return mailboxes, nil
}

type ListMessagesOpts struct {
	Mailbox string
	Limit   uint32
}

func ListMessages(conf *config.AccountData, opts *ListMessagesOpts, debug bool) ([]*imap.Message, error) {
	var messages []*imap.Message
	conn := NewConnection(conf)

	err := conn.Start(debug)
	if err != nil {
		return messages, err
	}
	defer conn.Close()

	mbox, err := conn.client.Select(opts.Mailbox, true)
	if err != nil {
		return messages, err
	}

	return getMessages(mbox, conn, opts.Limit)
}

func getMessages(mbox *imap.MailboxStatus, conn *IMAPConnection, limit uint32) ([]*imap.Message, error) {
	var start uint32
	var msgs []*imap.Message
	seqset := new(imap.SeqSet)
	messages := make(chan *imap.Message, 10)
	done := make(chan error, 1)

	switch {
	case limit == 0:
		start = 1
	case mbox.Messages > limit:
		start = mbox.Messages - limit + 1
	default:
		start = 1
	}

	seqset.AddRange(start, mbox.Messages)
	go func() {
		done <- conn.client.Fetch(seqset, []imap.FetchItem{imap.FetchEnvelope, imap.FetchFlags}, messages)
	}()

	for msg := range messages {
		msgs = append(msgs, msg)
	}

	if err := <-done; err != nil {
		return []*imap.Message{}, err
	}
	return msgs, nil
}

type FetchOpts struct {
	Mailbox     string
	IdList      []uint32
	WithHeaders bool
	WithBody    bool
	WithFlags   bool
	Peek        bool
}

func (o *FetchOpts) String() string {
	return fmt.Sprintf(
		"FetchOpts{Mailbox: %s, IdList: %v, WithHeaders: %t, WithBody: %t, Peek: %t}",
		o.Mailbox,
		o.IdList,
		o.WithHeaders,
		o.WithBody,
		o.Peek,
	)
}

func FetchMessages(conf *config.AccountData, opts *FetchOpts, debug bool) ([]*imap.Message, error) {
	var messages []*imap.Message
	conn := NewConnection(conf)

	err := conn.Start(debug)
	if err != nil {
		return messages, err
	}
	defer conn.Close()

	mbox, err := conn.client.Select(opts.Mailbox, true)
	if err != nil {
		return messages, err
	}

	return fetchMessage(mbox, conn, opts)
}

func fetchMessage(mbox *imap.MailboxStatus, conn *IMAPConnection, opts *FetchOpts) ([]*imap.Message, error) {
	var messageAcc []*imap.Message
	messages := make(chan *imap.Message, len(opts.IdList))
	done := make(chan error, 1)

	seqset := new(imap.SeqSet)

	for _, id := range opts.IdList {
		seqset.AddNum(id)
	}

	var items []imap.FetchItem
	if opts.WithHeaders {
		section := &imap.BodySectionName{Peek: opts.Peek, BodyPartName: imap.BodyPartName{Specifier: imap.HeaderSpecifier}}
		items = append(items, section.FetchItem())
	}

	items = append(items, imap.FetchEnvelope)

	if opts.WithBody {
		section := &imap.BodySectionName{Peek: opts.Peek, BodyPartName: imap.BodyPartName{Specifier: imap.TextSpecifier}}
		items = append(items, section.FetchItem())
	}

	if opts.WithFlags {
		items = append(items, imap.FetchFlags)
	}

	go func() {
		done <- conn.client.Fetch(seqset, items, messages)
	}()

	for m := range messages {
		messageAcc = append(messageAcc, m)
	}
	if err := <-done; err != nil {
		return []*imap.Message{}, err
	}
	return messageAcc, nil
}