package msg

import (
	"fmt"
	"io"
	"math/rand"
	"sync"
	"time"

	"github.com/emersion/go-message"
	_ "github.com/emersion/go-message/charset"
	"github.com/emersion/go-message/mail"
	"github.com/pkg/errors"

	"git.sr.ht/~rjarry/aerc/lib"
	"git.sr.ht/~rjarry/aerc/lib/ui"
	"git.sr.ht/~rjarry/aerc/logging"
	"git.sr.ht/~rjarry/aerc/models"
	"git.sr.ht/~rjarry/aerc/widgets"
	"git.sr.ht/~rjarry/aerc/worker/types"
	"git.sr.ht/~sircmpwn/getopt"
)

type Recall struct{}

func init() {
	register(Recall{})
}

func (Recall) Aliases() []string {
	return []string{"recall"}
}

func (Recall) Complete(aerc *widgets.Aerc, args []string) []string {
	return nil
}

func (Recall) Execute(aerc *widgets.Aerc, args []string) error {
	force := false

	opts, optind, err := getopt.Getopts(args, "f")
	if err != nil {
		return err
	}
	for _, opt := range opts {
		if opt.Option == 'f' {
			force = true
		}
	}

	if len(args) != optind {
		return errors.New("Usage: recall [-f]")
	}

	widget := aerc.SelectedTabContent().(widgets.ProvidesMessage)
	acct := widget.SelectedAccount()
	if acct == nil {
		return errors.New("No account selected")
	}
	if acct.SelectedDirectory() != acct.AccountConfig().Postpone && !force {
		return errors.New("Use -f to recall from outside the " +
			acct.AccountConfig().Postpone + " directory.")
	}
	store := widget.Store()
	if store == nil {
		return errors.New("Cannot perform action. Messages still loading")
	}

	msgInfo, err := widget.SelectedMessage()
	if err != nil {
		return errors.Wrap(err, "Recall failed")
	}
	logging.Infof("Recalling message %s", msgInfo.Envelope.MessageId)

	composer, err := widgets.NewComposer(aerc, acct, aerc.Config(),
		acct.AccountConfig(), acct.Worker(), "", msgInfo.RFC822Headers,
		models.OriginalMail{})
	if err != nil {
		return errors.Wrap(err, "Cannot open a new composer")
	}

	// focus the terminal since the header fields are likely already done
	composer.FocusTerminal()

	addTab := func() {
		subject := msgInfo.Envelope.Subject
		if subject == "" {
			subject = "Recalled email"
		}
		tab := aerc.NewTab(composer, subject)
		composer.OnHeaderChange("Subject", func(subject string) {
			if subject == "" {
				tab.Name = "New email"
			} else {
				tab.Name = subject
			}
			ui.Invalidate()
		})
		composer.OnClose(func(composer *widgets.Composer) {
			worker := composer.Worker()
			uids := []uint32{msgInfo.Uid}

			if acct.SelectedDirectory() != acct.AccountConfig().Postpone {
				return
			}

			deleteMessage := func() {
				worker.PostAction(&types.DeleteMessages{
					Uids: uids,
				}, func(msg types.WorkerMessage) {
					switch msg := msg.(type) {
					case *types.Done:
						aerc.PushStatus("Recalled message deleted", 10*time.Second)
					case *types.Error:
						aerc.PushError(msg.Error.Error())
					}
				})
			}

			if composer.Sent() {
				deleteMessage()
			} else {
				confirm := widgets.NewSelectorDialog(
					"Delete recalled message?",
					"If you proceed, the recalled message will be deleted.",
					[]string{"Cancel", "Proceed"}, 0, aerc.SelectedAccountUiConfig(),
					func(option string, err error) {
						aerc.CloseDialog()
						switch option {
						case "Proceed":
							deleteMessage()
						default:
						}
					},
				)
				aerc.AddDialog(confirm)
			}
		})
	}

	lib.NewMessageStoreView(msgInfo, acct.UiConfig().AutoMarkRead,
		store, aerc.Crypto, aerc.DecryptKeys,
		func(msg lib.MessageView, err error) {
			if err != nil {
				aerc.PushError(err.Error())
				return
			}

			var (
				path []int
				part *models.BodyStructure
			)
			if len(msg.BodyStructure().Parts) != 0 {
				path = lib.FindPlaintext(msg.BodyStructure(), path)
			}
			part, err = msg.BodyStructure().PartAtIndex(path)
			if part == nil || err != nil {
				part = msg.BodyStructure()
			}

			msg.FetchBodyPart(path, func(reader io.Reader) {
				header := message.Header{}
				header.SetText(
					"Content-Transfer-Encoding", part.Encoding)
				header.SetContentType(part.MIMEType, part.Params)
				header.SetText("Content-Description", part.Description)
				entity, err := message.New(header, reader)
				if err != nil {
					aerc.PushError(err.Error())
					addTab()
					return
				}
				mreader := mail.NewReader(entity)
				part, err := mreader.NextPart()
				if err != nil {
					aerc.PushError(err.Error())
					addTab()
					return
				}
				composer.SetContents(part.Body)
				if md := msg.MessageDetails(); md != nil {
					if md.IsEncrypted {
						composer.SetEncrypt(md.IsEncrypted)
					}
					if md.IsSigned {
						err = composer.SetSign(md.IsSigned)
						if err != nil {
							logging.Warnf("failed to set signed state: %v", err)
						}
					}
				}
				addTab()

				// add attachements if present
				var mu sync.Mutex
				parts := lib.FindAllNonMultipart(msg.BodyStructure(), nil, nil)
				for _, p := range parts {
					if lib.EqualParts(p, path) {
						continue
					}
					bs, err := msg.BodyStructure().PartAtIndex(p)
					if err != nil {
						logging.Infof("cannot get PartAtIndex %v: %v", p, err)
						continue
					}
					msg.FetchBodyPart(p, func(reader io.Reader) {
						mime := fmt.Sprintf("%s/%s", bs.MIMEType, bs.MIMESubType)
						params := lib.SetUtf8Charset(bs.Params)
						name, ok := params["name"]
						if !ok {
							name = fmt.Sprintf("%s_%s_%d", bs.MIMEType, bs.MIMESubType, rand.Uint64())
						}
						mu.Lock()
						composer.AddPartAttachment(name, mime, params, reader)
						mu.Unlock()
					})
				}
			})
		})

	return nil
}