package lib

import (
	"bytes"
	"fmt"
	"time"

	"git.iamthefij.com/iamthefij/slog"
	"github.com/emersion/go-imap"
	imapClient "github.com/emersion/go-imap/client"
)

const (
	maxChannels     = 10
	baseNotesFolder = "Notes"
)

type ContentType string

const (
	ContentTypePlainText ContentType = "text/plain"
	ContentTypeHtml      ContentType = `text/html; charset="UTF-8"`
)

// BuildEmail generates a buffer with the email contents
func BuildEmail(envelope imap.Envelope, body string, contentType ContentType) bytes.Buffer {
	if contentType == "" {
		contentType = ContentTypePlainText
	}

	var messageBuffer bytes.Buffer
	if envelope.From != nil && len(envelope.From) > 0 {
		messageBuffer.WriteString("From: " + envelope.From[0].Address() + "\r\n")
	}

	messageBuffer.WriteString("Date: " + envelope.Date.Format(time.RFC1123Z) + "\r\n")
	messageBuffer.WriteString("X-Mail-Created-Date: " + envelope.Date.Format(time.RFC1123Z) + "\r\n")
	messageBuffer.WriteString("Subject: " + envelope.Subject + "\r\n")
	messageBuffer.WriteString("Content-Type: " + string(contentType) + "\r\n")
	messageBuffer.WriteString("X-Uniform-Type-Identifier: com.apple.mail-note\r\n")
	messageBuffer.WriteString("\r\n")
	messageBuffer.WriteString(body)

	return messageBuffer
}

type Client struct {
	BaseClient *imapClient.Client
}

func (c *Client) Logout() error {
	if err := c.BaseClient.Logout(); err != nil {
		return fmt.Errorf("failed to logout: %w", err)
	}

	return nil
}

func (c *Client) SelectRW(folderName string) (*imap.MailboxStatus, error) {
	readOnly := false

	mbox, err := c.BaseClient.Select(folderName, readOnly)
	if err != nil {
		err = fmt.Errorf("failed slecting folder %s as read write: %w", folderName, err)
	}

	return mbox, err
}

func (c *Client) Select(folderName string) (*imap.MailboxStatus, error) {
	readOnly := true

	mbox, err := c.BaseClient.Select(folderName, readOnly)
	if err != nil {
		err = fmt.Errorf("failed slecting folder %s as read only: %w", folderName, err)
	}

	return mbox, err
}

func (c *Client) StoreNote(folderName string, envelope imap.Envelope, body string, contentType ContentType) error {
	b := BuildEmail(envelope, body, contentType)
	if err := c.BaseClient.Append(folderName, []string{}, time.Now(), &b); err != nil {
		return fmt.Errorf("failed to append new note to folder %s: %w", folderName, err)
	}

	return nil
}

func (c *Client) ListNoteFolders() ([]*NoteFolder, error) {
	mailboxes := make(chan *imap.MailboxInfo, maxChannels)
	done := make(chan error, 1)

	go func() {
		done <- c.BaseClient.List(baseNotesFolder, "*", mailboxes)
	}()

	results := []*NoteFolder{}
	for m := range mailboxes {
		results = append(results, NewNoteFolder(c, m.Name))
	}

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

	return results, nil
}

func (c *Client) GetNoteFolder(folderName string) (*NoteFolder, error) {
	mbox, err := c.Select(folderName)
	if err != nil {
		return nil, err
	}

	return NewNoteFolder(c, mbox.Name), nil
}

func (c Client) getMessages(seqset *imap.SeqSet) ([]*imap.Message, error) {
	messages := make(chan *imap.Message, maxChannels)
	done := make(chan error, 1)

	go func() {
		done <- c.BaseClient.Fetch(
			seqset,
			[]imap.FetchItem{
				imap.FetchEnvelope,
				imap.FetchUid,
				imap.FetchRFC822,
			},
			messages,
		)
	}()

	results := []*imap.Message{}
	for msg := range messages {
		results = append(results, msg)
	}

	err := <-done
	if err != nil {
		err = fmt.Errorf("failed to retrieve messages with seq %v from server: %w", seqset, err)
	}

	return results, err
}

// ListNotesInFolder returns a list of Notes in the provided folder
func (c Client) ListNotesInFolder(folder *NoteFolder) ([]*Note, error) {
	mbox, err := folder.Select()
	if err != nil {
		return nil, err
	}

	slog.Debugf("mailbox %s has %d messages", folder.Name, mbox.Messages)

	seqset := new(imap.SeqSet)
	seqset.AddRange(1, mbox.Messages)

	slog.Debugf("Fetching notes %v from %s", seqset, folder.Name)

	messages, err := c.getMessages(seqset)
	if err != nil {
		return nil, fmt.Errorf("failed to list messages: %w", err)
	}

	results := []*Note{}
	for _, message := range messages {
		results = append(results, NewNote(folder, message))
	}

	return results, nil
}

func (c Client) SearchNotes(folder *NoteFolder, criteria *imap.SearchCriteria) ([]*Note, error) {
	if _, err := folder.Select(); err != nil {
		return nil, err
	}

	ids, err := c.BaseClient.Search(criteria)
	if err != nil {
		return nil, fmt.Errorf("search on mail server failed: %w", err)
	}

	slog.Debugf("search result ids: %v", ids)

	if len(ids) == 0 {
		return []*Note{}, nil
	}

	seqset := new(imap.SeqSet)
	seqset.AddNum(ids...)

	messages, err := c.getMessages(seqset)
	if err != nil {
		return nil, fmt.Errorf("failed to get messages after search: %w", err)
	}

	results := []*Note{}
	for _, message := range messages {
		results = append(results, NewNote(folder, message))
	}

	return results, nil
}

func (c Client) SetFlagForNote(note Note, flags []interface{}) error {
	if _, err := note.Folder.SelectRW(); err != nil {
		return err
	}

	seqset := new(imap.SeqSet)
	seqset.AddNum(note.message.Uid)
	slog.Debugf("seqset to set flags on message: %v to %v\n", seqset, flags)

	silent := true
	item := imap.FormatFlagsOp(imap.AddFlags, silent)

	messages := make(chan *imap.Message)
	if err := c.BaseClient.UidStore(seqset, item, flags, messages); err != nil {
		return fmt.Errorf("failed to set note flags: %w", err)
	}

	for message := range messages {
		slog.Debugf("Set flag on message: %v\n", message)
	}

	return nil
}

func (c Client) DeleteNote(note Note) error {
	flags := []interface{}{imap.DeletedFlag}

	err := c.SetFlagForNote(note, flags)
	if err != nil {
		return fmt.Errorf("failed flag note as deleted: %w", err)
	}

	// deletedItems := make(chan uint32)
	if err := c.BaseClient.Expunge(nil); err != nil {
		return fmt.Errorf("expunge deleted messages: %w", err)
	}
	/* Don't know why this doesn't return anything on the channel
	 * for item := range deletedItems {
	 * 	fmt.Println(item)
	 * }
	 */

	return nil
}

func ConnectImap(hostname string, username string, password string) (*Client, error) {
	slog.Debugf("Connecting to server...")

	client, err := imapClient.DialTLS(hostname, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to IMAP server: %w", err)
	}

	slog.Debugf("Logging in...")

	err = client.Login(username, password)
	if err != nil {
		return nil, fmt.Errorf("failed to login: %w", err)
	}

	slog.Debugf("Logged in!")

	return &Client{client}, nil
}