Add intake worker
Subsystem to monitor IMAP mailbox for new messages. Introduces: - intake: worker that uses IDLE or polling to detect new emails. - imap: client wrapper for connection management and IMAP commands. - filter: logic for IMAP search and sender allow-list. - tracker: concurrency control to prevent processing the same UID twice. - backoff: for handling connection retries with jitter.
This commit is contained in:
dwrz
264
internal/imap/imap.go
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264
internal/imap/imap.go
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@@ -0,0 +1,264 @@
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// Package imap provides an IMAP client wrapper for monitoring and fetching
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// email messages. It handles connection management, IDLE support for push
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// notifications, and message operations like fetching and marking as seen.
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//
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// The client supports server-side filtering via [filter.Filters] to limit
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// which messages are returned by [Client.Unseen].
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package imap
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import (
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"context"
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"fmt"
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"log/slog"
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"time"
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"raven/internal/filter"
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"github.com/emersion/go-imap/v2"
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"github.com/emersion/go-imap/v2/imapclient"
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)
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// Config holds IMAP server connection parameters.
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type Config struct {
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// Host is the IMAP server hostname.
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Host string `yaml:"host"`
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// Password is the authentication password or app-specific password.
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Password string `yaml:"password"`
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// Port is the IMAP server port (typically "993" for TLS).
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Port string `yaml:"port"`
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// User is the authentication username, usually an email address.
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User string `yaml:"user"`
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}
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// Address returns the host:port string for dialing.
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func (c *Config) Address() string {
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return fmt.Sprintf("%s:%s", c.Host, c.Port)
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}
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// Validate checks that all required fields are present.
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func (c *Config) Validate() error {
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if c.Host == "" {
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return fmt.Errorf("missing host")
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}
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if c.Password == "" {
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return fmt.Errorf("missing password")
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}
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if c.Port == "" {
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return fmt.Errorf("missing port")
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}
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if c.User == "" {
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return fmt.Errorf("missing user")
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}
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return nil
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}
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// Client wraps an IMAP client with connection management and filtering.
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type Client struct {
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cfg Config
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filters filter.Filters
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client *imapclient.Client
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log *slog.Logger
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}
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// NewClient creates a new Client with the given configuration.
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// The client is not connected until [Client.Connect] is called.
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func NewClient(
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cfg Config,
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filters filter.Filters,
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log *slog.Logger,
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) (*Client, error) {
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if err := cfg.Validate(); err != nil {
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return nil, fmt.Errorf("invalid config: %v", err)
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}
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return &Client{
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cfg: cfg,
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filters: filters,
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log: log,
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}, nil
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}
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// Client returns the underlying imapclient.Client.
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// Returns nil if not connected.
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func (c *Client) Client() *imapclient.Client {
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return c.client
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}
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// Connect establishes a TLS connection to the IMAP server,
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// authenticates, and selects the INBOX.
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func (c *Client) Connect(
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ctx context.Context,
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log *slog.Logger,
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opts *imapclient.Options,
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) error {
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c.log = log
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c.log.InfoContext(ctx, "connecting to IMAP server")
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client, err := imapclient.DialTLS(c.cfg.Address(), opts)
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if err != nil {
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return fmt.Errorf("dial TLS: %w", err)
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}
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c.client = client
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c.log.InfoContext(ctx, "connected to IMAP server")
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c.log.InfoContext(ctx, "logging into to IMAP server")
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if err := client.Login(c.cfg.User, c.cfg.Password).Wait(); err != nil {
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return fmt.Errorf("login: %w", err)
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}
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c.log.InfoContext(ctx, "logged into IMAP server")
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c.log.InfoContext(ctx, "selecting INBOX")
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if _, err := client.Select("INBOX", nil).Wait(); err != nil {
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return fmt.Errorf("select: %w", err)
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}
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c.log.InfoContext(ctx, "selected INBOX")
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return nil
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}
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// CanIdle reports whether the server advertises IDLE capability (RFC 2177).
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func (c *Client) CanIdle() bool {
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return c.client.Caps().Has(imap.CapIdle)
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}
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// Disconnect logs out from the server and closes the connection.
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// Safe to call on a nil or disconnected client.
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func (c *Client) Disconnect(ctx context.Context) {
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if c.client == nil {
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return
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}
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c.log.InfoContext(ctx, "logging out")
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ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
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defer cancel()
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var done = make(chan error, 1)
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go func() {
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done <- c.client.Logout().Wait()
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}()
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select {
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case <-ctx.Done():
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c.log.InfoContext(
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ctx,
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"context closed",
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slog.Any("reason", ctx.Err()),
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)
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case err := <-done:
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if err != nil {
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c.log.Warn(
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"failed to logout from IMAP server",
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slog.Any("error", err),
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)
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}
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}
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c.client.Close()
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c.client = nil
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}
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// Fetch retrieves a message by UID. If peek is true, the message is
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// fetched without marking it as seen (using BODY.PEEK[]).
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func (c *Client) Fetch(uid imap.UID, peek bool) (
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*imapclient.FetchMessageBuffer, error,
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) {
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if c.client == nil {
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return nil, fmt.Errorf("client not connected")
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}
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opts := &imap.FetchOptions{Envelope: true, UID: true}
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if peek {
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opts.BodySection = []*imap.FetchItemBodySection{{Peek: true}}
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}
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res, err := c.client.Fetch(imap.UIDSetNum(uid), opts).Collect()
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if err != nil {
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return nil, fmt.Errorf("fetch: %w", err)
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}
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if len(res) == 0 {
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return nil, fmt.Errorf("message not found")
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}
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return res[0], nil
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}
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// Idle starts an IDLE command (RFC 2177) to wait for server notifications.
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// The caller must call Close on the returned command to end IDLE mode.
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func (c *Client) Idle() (*imapclient.IdleCommand, error) {
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return c.client.Idle()
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}
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// MarkSeen adds the \Seen flag to the message with the given UID.
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func (c *Client) MarkSeen(uid imap.UID) error {
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if c.client == nil {
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return fmt.Errorf("client not connected")
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}
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if _, err := c.client.Store(
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imap.UIDSetNum(uid),
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&imap.StoreFlags{
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Op: imap.StoreFlagsAdd,
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Silent: true,
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Flags: []imap.Flag{imap.FlagSeen},
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},
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nil,
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).Collect(); err != nil {
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return fmt.Errorf("collect: %w", err)
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}
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return nil
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}
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// Noop sends a NOOP command to refresh mailbox state.
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func (c *Client) Noop() error {
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if c.client == nil {
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return fmt.Errorf("client not connected")
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}
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return c.client.Noop().Wait()
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}
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// Unseen returns UIDs of messages matching the client's filters that
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// do not have the \Seen flag. Filters are applied server-side.
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func (c *Client) Unseen(ctx context.Context) ([]imap.UID, error) {
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sc := &imap.SearchCriteria{
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NotFlag: []imap.Flag{imap.FlagSeen},
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}
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if len(c.filters.Body) > 0 {
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sc.Body = c.filters.Body
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}
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if c.filters.From != "" {
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sc.Header = append(
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sc.Header,
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imap.SearchCriteriaHeaderField{
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Key: "From",
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Value: c.filters.From,
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},
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)
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}
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if c.filters.Subject != "" {
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sc.Header = append(
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sc.Header,
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imap.SearchCriteriaHeaderField{
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Key: "Subject",
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Value: c.filters.Subject,
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},
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)
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}
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if c.filters.To != "" {
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sc.Header = append(
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sc.Header,
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imap.SearchCriteriaHeaderField{
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Key: "To",
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Value: c.filters.To,
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},
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)
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}
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res, err := c.client.UIDSearch(sc, nil).Wait()
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if err != nil {
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return nil, fmt.Errorf("search: %v", err)
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}
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uids := res.AllUIDs()
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return uids, nil
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}
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