Implement native iPhone entry editor

crates/storage/src/document.rs

@@ -320,6 +320,10 @@ impl EntryDocument {
         self.conflict_token
     }
 
+    pub fn is_modified(&self) -> bool {
+        self.modified
+    }
+
     pub fn add(
         &mut self,
         index: usize,

crates/storage/src/mobile_authentication.rs

@@ -1,6 +1,6 @@
 //! Shared mobile authentication state; Swift only supplies input and presents results.
 
-use std::{error::Error, fmt, sync::Mutex};
+use std::{collections::BTreeMap, error::Error, fmt, sync::Mutex};
 
 use crate::{
     authentication::{
@@ -10,9 +10,17 @@ use crate::{
     crypto::{CryptoError, KeyInfo, KeyStore, SecretProvider, SecretProviderError},
     document::{DocumentError, EntryDocument, EntryDocumentService, EntryFieldId},
     git::{AutomaticEntryCommitter, GitIdentity},
-    mobile_entry::{MobileEntryPage, MobileEntryValueError, field_value},
-    repository::{EntryPath, Repository, RepositoryError, SecretBytes},
+    mobile_entry::{
+        MobileEntryDraft, MobileEntryEditorError, MobileEntryEditorFieldKind,
+        MobileEntryEditorInput, MobileEntryEditorPage, MobileEntryEditorSession, MobileEntryPage,
+        MobileEntryValueError, field_value,
+    },
+    recipient::RecipientPolicyManager,
+    repository::{
+        DirectoryPath, EncryptedEntry, EntryPath, Repository, RepositoryError, SecretBytes,
+    },
     secret_store::{SecretProtectionPolicy, SecretStoreError},
+    write::{VaultWriter, WriteError},
 };
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
@@ -26,6 +34,7 @@ pub enum MobileAuthenticationErrorKind {
     Entry,
     SecureStorage,
     Expired,
+    Conflict,
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -150,6 +159,8 @@ struct ActiveMobileLease {
 struct MobileAuthenticationStatus {
     biometric_unlock_enabled: bool,
     active: Option<ActiveMobileLease>,
+    next_editor_id: u64,
+    editors: BTreeMap<u64, MobileEntryDraft>,
 }
 
 /// One process-wide mobile authentication lease shared by every tab and viewer.
@@ -181,6 +192,8 @@ impl MobileAuthentication {
             status: Mutex::new(MobileAuthenticationStatus {
                 biometric_unlock_enabled: config.biometric_unlock_enabled(),
                 active: None,
+                next_editor_id: 0,
+                editors: BTreeMap::new(),
             }),
             config,
             repository,
@@ -197,17 +210,26 @@ impl MobileAuthentication {
     ) -> Result<MobileAuthenticationState, MobileAuthenticationError> {
         let entry = EntryPath::parse(path).map_err(entry_error)?;
         let ciphertext = self.repository.read_entry(&entry).map_err(entry_error)?;
-        let candidates = self.keys.decrypting_keys(&ciphertext).map_err(key_error)?;
+        self.unlock_ciphertext(&ciphertext, passphrase)
+    }
+
+    fn unlock_ciphertext(
+        &self,
+        ciphertext: &EncryptedEntry,
+        passphrase: Option<SecretBytes>,
+    ) -> Result<MobileAuthenticationState, MobileAuthenticationError> {
+        let candidates = self.keys.decrypting_keys(ciphertext).map_err(key_error)?;
 
         if let Some(active) = self.take_active()? {
             let mut provider = KeyOnlyProvider::new(active.handle.clone(), &active.key);
-            if self.keys.decrypt(&ciphertext, &mut provider).is_ok() {
+            if self.keys.decrypt(ciphertext, &mut provider).is_ok() {
                 self.restore_active(active)?;
                 return self.state();
             }
             self.session
                 .manual_lock()
                 .map_err(MobileAuthenticationError::authentication)?;
+            self.status()?.editors.clear();
         }
 
         let biometric_enabled = self.status()?.biometric_unlock_enabled;
@@ -220,7 +242,7 @@ impl MobileAuthentication {
                         .authenticate_with_passphrase(key, candidate)
                         .map_err(MobileAuthenticationError::authentication)?;
                     let mut provider = KeyOnlyProvider::new(handle.clone(), key);
-                    match self.keys.decrypt(&ciphertext, &mut provider) {
+                    match self.keys.decrypt(ciphertext, &mut provider) {
                         Ok(plaintext) => {
                             drop(plaintext);
                             if biometric_enabled {
@@ -257,7 +279,7 @@ impl MobileAuthentication {
                         Err(_) => continue,
                     };
                     let mut provider = KeyOnlyProvider::new(handle.clone(), key);
-                    if let Ok(plaintext) = self.keys.decrypt(&ciphertext, &mut provider) {
+                    if let Ok(plaintext) = self.keys.decrypt(ciphertext, &mut provider) {
                         drop(plaintext);
                         self.set_active(handle, key.clone())?;
                         return self.state();
@@ -312,6 +334,7 @@ impl MobileAuthentication {
             let mut status = self.status()?;
             status.biometric_unlock_enabled = false;
             status.active = None;
+            status.editors.clear();
         }
         self.state()
     }
@@ -324,6 +347,7 @@ impl MobileAuthentication {
         let mut status = self.status()?;
         if remaining.is_none() {
             status.active = None;
+            status.editors.clear();
         }
         Ok(MobileAuthenticationState {
             unlocked: status.active.is_some(),
@@ -391,11 +415,191 @@ impl MobileAuthentication {
         Ok(MobileEntryPage::from_document(&document))
     }
 
+    pub fn begin_entry_editor(
+        &self,
+        path: &str,
+    ) -> Result<MobileEntryEditorSession, MobileAuthenticationError> {
+        let document = self.open_active_document(path)?;
+        self.store_editor(MobileEntryDraft::new(document, false))
+    }
+
+    pub fn begin_create_entry(
+        &self,
+        directory: &str,
+        name: &str,
+        passphrase: Option<SecretBytes>,
+    ) -> Result<MobileEntryEditorSession, MobileAuthenticationError> {
+        let directory = DirectoryPath::parse(directory).map_err(entry_error)?;
+        let leaf = EntryPath::parse(name).map_err(entry_error)?;
+        if leaf
+            .as_path()
+            .parent()
+            .is_some_and(|parent| !parent.as_os_str().is_empty())
+        {
+            return Err(entry_detail(
+                "Entry Name Is Invalid",
+                "enter a name without a folder separator",
+            ));
+        }
+        let path =
+            EntryPath::parse(directory.as_path().join(leaf.as_path())).map_err(entry_error)?;
+        let path_text = path.to_string();
+        if VaultWriter::new(&self.repository, &self.keys)
+            .entry_exists(&path_text)
+            .map_err(|error| entry_detail("Password Entry Is Unavailable", error))?
+        {
+            return Err(entry_detail(
+                "Password Already Exists",
+                "Choose a different entry name.",
+            ));
+        }
+        let recipients = RecipientPolicyManager::new(&self.repository, &self.keys)
+            .resolve_for_entry(&path, None)
+            .map_err(|error| entry_detail("Recipients Are Unavailable", error))?;
+        let probe = self
+            .keys
+            .encrypt(
+                SecretBytes::new(b"IronStorage mobile entry creation".to_vec()),
+                recipients.recipients(),
+            )
+            .map_err(key_error)?;
+        self.unlock_ciphertext(&probe, passphrase)?;
+        let mut document = self.open_active_document(&path_text)?;
+        document
+            .add(
+                0,
+                crate::document::EntryFieldDraft::line(Vec::new()).map_err(document_error)?,
+            )
+            .map_err(document_error)?;
+        self.store_editor(MobileEntryDraft::new(document, true))
+    }
+
+    pub fn entry_editor(
+        &self,
+        editor: u64,
+    ) -> Result<MobileEntryEditorPage, MobileAuthenticationError> {
+        self.ensure_active()?;
+        self.status()?
+            .editors
+            .get(&editor)
+            .map(MobileEntryDraft::page)
+            .ok_or_else(editor_missing)
+    }
+
+    pub fn update_entry_editor(
+        &self,
+        editor: u64,
+        fields: Vec<MobileEntryEditorInput>,
+    ) -> Result<MobileEntryEditorPage, MobileAuthenticationError> {
+        self.ensure_active()?;
+        let mut status = self.status()?;
+        let draft = status.editors.get_mut(&editor).ok_or_else(editor_missing)?;
+        draft.apply(fields).map_err(editor_error)?;
+        Ok(draft.page())
+    }
+
+    pub fn add_entry_editor_field(
+        &self,
+        editor: u64,
+        kind: MobileEntryEditorFieldKind,
+        name: Option<String>,
+        value: String,
+    ) -> Result<MobileEntryEditorPage, MobileAuthenticationError> {
+        self.ensure_active()?;
+        let mut status = self.status()?;
+        let draft = status.editors.get_mut(&editor).ok_or_else(editor_missing)?;
+        draft.add(kind, name, value).map_err(editor_error)?;
+        Ok(draft.page())
+    }
+
+    pub fn remove_entry_editor_field(
+        &self,
+        editor: u64,
+        field: u64,
+    ) -> Result<MobileEntryEditorPage, MobileAuthenticationError> {
+        self.ensure_active()?;
+        let mut status = self.status()?;
+        let draft = status.editors.get_mut(&editor).ok_or_else(editor_missing)?;
+        draft.remove(field).map_err(editor_error)?;
+        Ok(draft.page())
+    }
+
+    pub fn reorder_entry_editor_field(
+        &self,
+        editor: u64,
+        field: u64,
+        index: usize,
+    ) -> Result<MobileEntryEditorPage, MobileAuthenticationError> {
+        self.ensure_active()?;
+        let mut status = self.status()?;
+        let draft = status.editors.get_mut(&editor).ok_or_else(editor_missing)?;
+        draft.reorder(field, index).map_err(editor_error)?;
+        Ok(draft.page())
+    }
+
+    pub fn generate_entry_editor_password(
+        &self,
+        editor: u64,
+        length: Option<u32>,
+        no_symbols: bool,
+    ) -> Result<MobileEntryEditorPage, MobileAuthenticationError> {
+        self.ensure_active()?;
+        let mut status = self.status()?;
+        let draft = status.editors.get_mut(&editor).ok_or_else(editor_missing)?;
+        draft
+            .generate_password(length, no_symbols)
+            .map_err(editor_error)?;
+        Ok(draft.page())
+    }
+
+    pub fn save_entry_editor(
+        &self,
+        editor: u64,
+        fields: Vec<MobileEntryEditorInput>,
+    ) -> Result<MobileEntryPage, MobileAuthenticationError> {
+        self.ensure_active()?;
+        let mut draft = self
+            .status()?
+            .editors
+            .remove(&editor)
+            .ok_or_else(editor_missing)?;
+        if let Err(error) = draft.apply(fields) {
+            self.restore_editor(editor, draft)?;
+            return Err(editor_error(error));
+        }
+        let path = draft.document().path().to_string();
+        let mut committer = match AutomaticEntryCommitter::for_entry(
+            &self.repository,
+            &path,
+            GitIdentity::ironstorage(),
+        ) {
+            Ok(committer) => committer,
+            Err(error) => {
+                self.restore_editor(editor, draft)?;
+                return Err(entry_detail("Password Entry Could Not Be Saved", error));
+            }
+        };
+        if let Err(error) = EntryDocumentService::new(&self.repository, &self.keys)
+            .save_recoverable(draft.document(), None, &mut committer)
+        {
+            self.restore_editor(editor, draft)?;
+            return Err(document_error(error));
+        }
+        Ok(MobileEntryPage::from_document(draft.document()))
+    }
+
+    pub fn discard_entry_editor(&self, editor: u64) -> Result<(), MobileAuthenticationError> {
+        self.status()?.editors.remove(&editor);
+        Ok(())
+    }
+
     pub fn manual_lock(&self) -> Result<(), MobileAuthenticationError> {
         self.session
             .manual_lock()
             .map_err(MobileAuthenticationError::authentication)?;
-        self.status()?.active = None;
+        let mut status = self.status()?;
+        status.active = None;
+        status.editors.clear();
         Ok(())
     }
 
@@ -403,7 +607,9 @@ impl MobileAuthentication {
         self.session
             .cancel()
             .map_err(MobileAuthenticationError::authentication)?;
-        self.status()?.active = None;
+        let mut status = self.status()?;
+        status.active = None;
+        status.editors.clear();
         Ok(())
     }
 
@@ -447,6 +653,48 @@ impl MobileAuthentication {
         Ok(())
     }
 
+    fn ensure_active(&self) -> Result<(), MobileAuthenticationError> {
+        let handle = self
+            .status()?
+            .active
+            .as_ref()
+            .map(|active| active.handle.clone())
+            .ok_or_else(locked_error)?;
+        if let Err(error) = handle.ensure_active() {
+            let mut status = self.status()?;
+            status.active = None;
+            status.editors.clear();
+            return Err(MobileAuthenticationError::authentication(error));
+        }
+        Ok(())
+    }
+
+    fn store_editor(
+        &self,
+        draft: MobileEntryDraft,
+    ) -> Result<MobileEntryEditorSession, MobileAuthenticationError> {
+        let mut status = self.status()?;
+        let id = status.next_editor_id;
+        status.next_editor_id = status.next_editor_id.checked_add(1).ok_or_else(|| {
+            entry_detail(
+                "Entry Editor Is Unavailable",
+                "entry editor identifiers are exhausted",
+            )
+        })?;
+        let page = draft.page();
+        status.editors.insert(id, draft);
+        Ok(MobileEntryEditorSession::new(id, page))
+    }
+
+    fn restore_editor(
+        &self,
+        editor: u64,
+        draft: MobileEntryDraft,
+    ) -> Result<(), MobileAuthenticationError> {
+        self.status()?.editors.insert(editor, draft);
+        Ok(())
+    }
+
     fn open_active_document(&self, path: &str) -> Result<EntryDocument, MobileAuthenticationError> {
         let (handle, key) = {
             let status = self.status()?;
@@ -519,13 +767,32 @@ fn locked_error() -> MobileAuthenticationError {
 }
 
 fn document_error(error: DocumentError) -> MobileAuthenticationError {
-    entry_detail("Password Entry Is Unavailable", error)
+    let kind = if matches!(
+        &error,
+        DocumentError::Write(WriteError::ConcurrentModification { .. })
+    ) {
+        MobileAuthenticationErrorKind::Conflict
+    } else {
+        MobileAuthenticationErrorKind::Entry
+    };
+    MobileAuthenticationError::new(kind, "Password Entry Could Not Be Saved", error.to_string())
 }
 
 fn value_error(error: MobileEntryValueError) -> MobileAuthenticationError {
     entry_detail("Field Value Is Unavailable", error)
 }
 
+fn editor_error(error: MobileEntryEditorError) -> MobileAuthenticationError {
+    entry_detail("Entry Draft Is Invalid", error)
+}
+
+fn editor_missing() -> MobileAuthenticationError {
+    entry_detail(
+        "Entry Draft Is Unavailable",
+        "the entry draft was discarded or locked",
+    )
+}
+
 fn entry_detail(title: &str, error: impl fmt::Display) -> MobileAuthenticationError {
     MobileAuthenticationError::new(
         MobileAuthenticationErrorKind::Entry,

crates/storage/src/mobile_entry.rs

@@ -1,11 +1,12 @@
 //! Storage-owned projection of lossless entry documents for native mobile viewers.
 
-use std::{error::Error, fmt};
+use std::{collections::BTreeSet, error::Error, fmt, num::NonZeroUsize};
 
 use crate::document::{
-    DocumentError, EntryDocument, EntryField, EntryFieldDiagnostic, EntryFieldId, EntryFieldKind,
-    EntrySensitivity,
+    DocumentError, EntryDocument, EntryField, EntryFieldDiagnostic, EntryFieldDraft, EntryFieldId,
+    EntryFieldKind, EntrySensitivity,
 };
+use crate::generate::{GenerateError, GeneratorConfig, MAX_PASSWORD_LENGTH};
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum MobileEntrySectionKind {
@@ -104,6 +105,352 @@ pub struct MobileEntryPage {
     sections: Vec<MobileEntrySection>,
 }
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum MobileEntryEditorFieldKind {
+    Password,
+    Field,
+    Note,
+    OtpUri,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct MobileEntryEditorField {
+    id: u64,
+    kind: MobileEntryEditorFieldKind,
+    name: Option<String>,
+    label: String,
+    system_image: String,
+    value: Option<String>,
+    masked_value: String,
+    diagnostic: Option<String>,
+    sensitive: bool,
+    multiline: bool,
+    name_editable: bool,
+    removable: bool,
+    reorderable: bool,
+}
+
+impl MobileEntryEditorField {
+    pub fn id(&self) -> u64 {
+        self.id
+    }
+
+    pub fn kind(&self) -> MobileEntryEditorFieldKind {
+        self.kind
+    }
+
+    pub fn name(&self) -> Option<&str> {
+        self.name.as_deref()
+    }
+
+    pub fn label(&self) -> &str {
+        &self.label
+    }
+
+    pub fn system_image(&self) -> &str {
+        &self.system_image
+    }
+
+    pub fn value(&self) -> Option<&str> {
+        self.value.as_deref()
+    }
+
+    pub fn masked_value(&self) -> &str {
+        &self.masked_value
+    }
+
+    pub fn diagnostic(&self) -> Option<&str> {
+        self.diagnostic.as_deref()
+    }
+
+    pub fn sensitive(&self) -> bool {
+        self.sensitive
+    }
+
+    pub fn multiline(&self) -> bool {
+        self.multiline
+    }
+
+    pub fn name_editable(&self) -> bool {
+        self.name_editable
+    }
+
+    pub fn removable(&self) -> bool {
+        self.removable
+    }
+
+    pub fn reorderable(&self) -> bool {
+        self.reorderable
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct MobileEntryEditorPage {
+    path: String,
+    title: String,
+    fields: Vec<MobileEntryEditorField>,
+    dirty: bool,
+    creating: bool,
+    default_password_length: u32,
+    maximum_password_length: u32,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct MobileEntryEditorSession {
+    id: u64,
+    page: MobileEntryEditorPage,
+}
+
+impl MobileEntryEditorSession {
+    pub fn new(id: u64, page: MobileEntryEditorPage) -> Self {
+        Self { id, page }
+    }
+
+    pub fn id(&self) -> u64 {
+        self.id
+    }
+
+    pub fn page(&self) -> &MobileEntryEditorPage {
+        &self.page
+    }
+}
+
+impl MobileEntryEditorPage {
+    pub fn path(&self) -> &str {
+        &self.path
+    }
+
+    pub fn title(&self) -> &str {
+        &self.title
+    }
+
+    pub fn fields(&self) -> &[MobileEntryEditorField] {
+        &self.fields
+    }
+
+    pub fn dirty(&self) -> bool {
+        self.dirty
+    }
+
+    pub fn creating(&self) -> bool {
+        self.creating
+    }
+
+    pub fn default_password_length(&self) -> u32 {
+        self.default_password_length
+    }
+
+    pub fn maximum_password_length(&self) -> u32 {
+        self.maximum_password_length
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct MobileEntryEditorInput {
+    id: u64,
+    name: Option<String>,
+    value: Option<String>,
+}
+
+impl MobileEntryEditorInput {
+    pub fn new(id: u64, name: Option<String>, value: Option<String>) -> Self {
+        Self { id, name, value }
+    }
+}
+
+pub struct MobileEntryDraft {
+    document: EntryDocument,
+    creating: bool,
+}
+
+impl MobileEntryDraft {
+    pub fn new(document: EntryDocument, creating: bool) -> Self {
+        Self { document, creating }
+    }
+
+    pub fn page(&self) -> MobileEntryEditorPage {
+        let fields = self
+            .document
+            .fields()
+            .iter()
+            .enumerate()
+            .map(|(index, field)| editor_field(index, field))
+            .collect();
+        MobileEntryEditorPage {
+            path: self.document.path().to_string(),
+            title: self
+                .document
+                .path()
+                .as_path()
+                .file_name()
+                .and_then(|name| name.to_str())
+                .unwrap_or("Password")
+                .to_owned(),
+            fields,
+            dirty: self.document.is_modified(),
+            creating: self.creating,
+            default_password_length: GeneratorConfig::pass_defaults().default_length().get() as u32,
+            maximum_password_length: MAX_PASSWORD_LENGTH as u32,
+        }
+    }
+
+    pub fn apply(
+        &mut self,
+        inputs: Vec<MobileEntryEditorInput>,
+    ) -> Result<(), MobileEntryEditorError> {
+        if inputs.len() != self.document.fields().len() {
+            return Err(MobileEntryEditorError::FieldSetChanged);
+        }
+        let mut seen = BTreeSet::new();
+        let mut replacements = Vec::with_capacity(inputs.len());
+        for input in inputs {
+            if !seen.insert(input.id) {
+                return Err(MobileEntryEditorError::FieldSetChanged);
+            }
+            let id = EntryFieldId::from_value(input.id);
+            let field = self
+                .document
+                .field(id)
+                .ok_or(MobileEntryEditorError::FieldSetChanged)?;
+            if let Some(value) = input.value {
+                replacements.push((id, editor_draft(field, input.name, value)?));
+            } else if field.metadata().diagnostic() != Some(EntryFieldDiagnostic::NonUtf8Value) {
+                return Err(MobileEntryEditorError::NonUtf8);
+            }
+        }
+        for (id, replacement) in replacements {
+            self.document.update(id, replacement)?;
+        }
+        Ok(())
+    }
+
+    pub fn add(
+        &mut self,
+        kind: MobileEntryEditorFieldKind,
+        name: Option<String>,
+        value: String,
+    ) -> Result<(), MobileEntryEditorError> {
+        let draft = match kind {
+            MobileEntryEditorFieldKind::Password => {
+                return Err(MobileEntryEditorError::ProtectedPasswordField);
+            }
+            MobileEntryEditorFieldKind::Field => EntryFieldDraft::field(
+                name.ok_or(MobileEntryEditorError::MissingFieldName)?,
+                value.into_bytes(),
+            )?,
+            MobileEntryEditorFieldKind::Note => {
+                EntryFieldDraft::field("notes", value.into_bytes())?
+            }
+            MobileEntryEditorFieldKind::OtpUri => EntryFieldDraft::otp_uri(value.into_bytes())?,
+        };
+        self.document.add(self.document.fields().len(), draft)?;
+        Ok(())
+    }
+
+    pub fn remove(&mut self, id: u64) -> Result<(), MobileEntryEditorError> {
+        let id = EntryFieldId::from_value(id);
+        if self
+            .document
+            .fields()
+            .first()
+            .is_some_and(|field| field.id() == id)
+        {
+            return Err(MobileEntryEditorError::ProtectedPasswordField);
+        }
+        self.document.remove(id)?;
+        Ok(())
+    }
+
+    pub fn reorder(&mut self, id: u64, index: usize) -> Result<(), MobileEntryEditorError> {
+        let id = EntryFieldId::from_value(id);
+        if index == 0
+            || self
+                .document
+                .fields()
+                .first()
+                .is_some_and(|field| field.id() == id)
+        {
+            return Err(MobileEntryEditorError::ProtectedPasswordField);
+        }
+        self.document.reorder(id, index)?;
+        Ok(())
+    }
+
+    pub fn generate_password(
+        &mut self,
+        length: Option<u32>,
+        no_symbols: bool,
+    ) -> Result<(), MobileEntryEditorError> {
+        let length = length
+            .map(|length| {
+                usize::try_from(length)
+                    .ok()
+                    .and_then(NonZeroUsize::new)
+                    .ok_or(MobileEntryEditorError::Generate(
+                        GenerateError::InvalidLength,
+                    ))
+            })
+            .transpose()?;
+        let generated = GeneratorConfig::pass_defaults().generate_secret(length, no_symbols)?;
+        let value = generated.expose().to_vec();
+        if let Some(password) = self
+            .document
+            .fields()
+            .iter()
+            .find(|field| field.metadata().kind() == EntryFieldKind::Password)
+        {
+            self.document
+                .update(password.id(), EntryFieldDraft::line(value)?)?;
+        } else {
+            self.document.add(0, EntryFieldDraft::line(value)?)?;
+        }
+        Ok(())
+    }
+
+    pub fn document(&self) -> &EntryDocument {
+        &self.document
+    }
+}
+
+#[derive(Debug)]
+pub enum MobileEntryEditorError {
+    Document(DocumentError),
+    Generate(GenerateError),
+    FieldSetChanged,
+    MissingFieldName,
+    ProtectedPasswordField,
+    NonUtf8,
+}
+
+impl fmt::Display for MobileEntryEditorError {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Document(error) => error.fmt(formatter),
+            Self::Generate(error) => error.fmt(formatter),
+            Self::FieldSetChanged => formatter.write_str("the entry fields changed while editing"),
+            Self::MissingFieldName => formatter.write_str("a named field requires a name"),
+            Self::ProtectedPasswordField => {
+                formatter.write_str("the first password field cannot be removed or moved")
+            }
+            Self::NonUtf8 => formatter.write_str("the entry field is not valid UTF-8"),
+        }
+    }
+}
+
+impl Error for MobileEntryEditorError {}
+
+impl From<DocumentError> for MobileEntryEditorError {
+    fn from(error: DocumentError) -> Self {
+        Self::Document(error)
+    }
+}
+
+impl From<GenerateError> for MobileEntryEditorError {
+    fn from(error: GenerateError) -> Self {
+        Self::Generate(error)
+    }
+}
+
 impl MobileEntryPage {
     pub fn from_document(document: &EntryDocument) -> Self {
         let title = document
@@ -213,12 +560,71 @@ fn mobile_field(field: &EntryField) -> MobileEntryField {
     }
 }
 
+fn editor_field(index: usize, field: &EntryField) -> MobileEntryEditorField {
+    let metadata = field.metadata();
+    let kind = if is_named_note(field) {
+        MobileEntryEditorFieldKind::Note
+    } else {
+        match metadata.kind() {
+            EntryFieldKind::Password => MobileEntryEditorFieldKind::Password,
+            EntryFieldKind::OtpUri => MobileEntryEditorFieldKind::OtpUri,
+            EntryFieldKind::Note => MobileEntryEditorFieldKind::Note,
+            EntryFieldKind::Username
+            | EntryFieldKind::Email
+            | EntryFieldKind::Url
+            | EntryFieldKind::Field => MobileEntryEditorFieldKind::Field,
+        }
+    };
+    let sensitive = matches!(
+        kind,
+        MobileEntryEditorFieldKind::Password | MobileEntryEditorFieldKind::OtpUri
+    );
+    MobileEntryEditorField {
+        id: field.id().value(),
+        kind,
+        name: metadata.name().map(str::to_owned),
+        label: label(field),
+        system_image: system_image(metadata.kind()).to_owned(),
+        value: String::from_utf8(field.value().to_vec()).ok(),
+        masked_value: if metadata.sensitivity() == EntrySensitivity::Empty {
+            "Empty"
+        } else if sensitive {
+            "Hidden"
+        } else {
+            "Unavailable"
+        }
+        .to_owned(),
+        diagnostic: metadata.diagnostic().map(diagnostic),
+        sensitive,
+        multiline: matches!(kind, MobileEntryEditorFieldKind::Note)
+            || field.value().contains(&b'\n'),
+        name_editable: matches!(kind, MobileEntryEditorFieldKind::Field),
+        removable: index > 0,
+        reorderable: index > 0,
+    }
+}
+
+fn editor_draft(
+    field: &EntryField,
+    name: Option<String>,
+    value: String,
+) -> Result<EntryFieldDraft, MobileEntryEditorError> {
+    Ok(match field.metadata().kind() {
+        EntryFieldKind::Password => EntryFieldDraft::line(value.into_bytes())?,
+        EntryFieldKind::OtpUri => EntryFieldDraft::otp_uri(value.into_bytes())?,
+        EntryFieldKind::Note => EntryFieldDraft::multiline(value.into_bytes()),
+        EntryFieldKind::Username
+        | EntryFieldKind::Email
+        | EntryFieldKind::Url
+        | EntryFieldKind::Field => EntryFieldDraft::field(
+            name.ok_or(MobileEntryEditorError::MissingFieldName)?,
+            value.into_bytes(),
+        )?,
+    })
+}
+
 fn section_kind(field: &EntryField) -> MobileEntrySectionKind {
-    if field.metadata().name().is_some_and(|name| {
-        ["comment", "comments", "note", "notes"]
-            .iter()
-            .any(|candidate| name.eq_ignore_ascii_case(candidate))
-    }) {
+    if is_named_note(field) {
         return MobileEntrySectionKind::Notes;
     }
     match field.metadata().kind() {
@@ -232,6 +638,14 @@ fn section_kind(field: &EntryField) -> MobileEntrySectionKind {
     }
 }
 
+fn is_named_note(field: &EntryField) -> bool {
+    field.metadata().name().is_some_and(|name| {
+        ["comment", "comments", "note", "notes"]
+            .iter()
+            .any(|candidate| name.eq_ignore_ascii_case(candidate))
+    })
+}
+
 fn label(field: &EntryField) -> String {
     if field.metadata().kind() == EntryFieldKind::Password {
         return "Password".to_owned();