/// Email header — stored locally after sync, body fetched on demand.
class Email {
  final String id; // "<accountId>:<uid>"
  final String accountId;
  final String mailboxPath;
  final int uid;
  final String? subject;
  final DateTime? sentAt;
  final DateTime receivedAt;
  final List<EmailAddress> from;
  final List<EmailAddress> to;
  final List<EmailAddress> cc;
  final String? preview;
  final bool isSeen;
  final bool isFlagged;
  final bool hasAttachment;
  final String? threadId;
  final String? messageId;
  final String? inReplyTo;
  // Space-separated RFC 2822 References header value.
  final String? references;
  final DateTime? snoozedUntil;
  final String? snoozedFromMailboxPath;
  // RFC 2369 List-Unsubscribe header value, e.g. "<mailto:...>, <https://...>".
  final String? listUnsubscribeHeader;

  const Email({
    required this.id,
    required this.accountId,
    required this.mailboxPath,
    required this.uid,
    this.subject,
    this.sentAt,
    required this.receivedAt,
    required this.from,
    required this.to,
    required this.cc,
    this.preview,
    required this.isSeen,
    required this.isFlagged,
    required this.hasAttachment,
    this.threadId,
    this.messageId,
    this.inReplyTo,
    this.references,
    this.snoozedUntil,
    this.snoozedFromMailboxPath,
    this.listUnsubscribeHeader,
  });

  factory Email.fromJson(Map<String, dynamic> json) {
    return Email(
      id: json['id'] as String,
      accountId: json['accountId'] as String,
      mailboxPath: json['mailboxPath'] as String,
      uid: json['uid'] as int,
      subject: json['subject'] as String?,
      sentAt: json['sentAt'] != null
          ? DateTime.parse(json['sentAt'] as String)
          : null,
      receivedAt: DateTime.parse(json['receivedAt'] as String),
      from: (json['from'] as List<dynamic>)
          .map((e) => EmailAddress.fromJson(e as Map<String, dynamic>))
          .toList(),
      to: (json['to'] as List<dynamic>)
          .map((e) => EmailAddress.fromJson(e as Map<String, dynamic>))
          .toList(),
      cc: (json['cc'] as List<dynamic>)
          .map((e) => EmailAddress.fromJson(e as Map<String, dynamic>))
          .toList(),
      preview: json['preview'] as String?,
      isSeen: json['isSeen'] as bool,
      isFlagged: json['isFlagged'] as bool,
      hasAttachment: json['hasAttachment'] as bool,
      threadId: json['threadId'] as String?,
      messageId: json['messageId'] as String?,
      inReplyTo: json['inReplyTo'] as String?,
      references: json['references'] as String?,
      snoozedUntil: json['snoozedUntil'] != null
          ? DateTime.parse(json['snoozedUntil'] as String)
          : null,
      snoozedFromMailboxPath: json['snoozedFromMailboxPath'] as String?,
      listUnsubscribeHeader: json['listUnsubscribeHeader'] as String?,
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'accountId': accountId,
      'mailboxPath': mailboxPath,
      'uid': uid,
      'subject': subject,
      'sentAt': sentAt?.toIso8601String(),
      'receivedAt': receivedAt.toIso8601String(),
      'from': from.map((e) => e.toJson()).toList(),
      'to': to.map((e) => e.toJson()).toList(),
      'cc': cc.map((e) => e.toJson()).toList(),
      'preview': preview,
      'isSeen': isSeen,
      'isFlagged': isFlagged,
      'hasAttachment': hasAttachment,
      'threadId': threadId,
      'messageId': messageId,
      'inReplyTo': inReplyTo,
      'references': references,
      'snoozedUntil': snoozedUntil?.toIso8601String(),
      'snoozedFromMailboxPath': snoozedFromMailboxPath,
      'listUnsubscribeHeader': listUnsubscribeHeader,
    };
  }

  Email copyWith({
    String? id,
    String? accountId,
    String? mailboxPath,
    int? uid,
    String? subject,
    DateTime? sentAt,
    DateTime? receivedAt,
    List<EmailAddress>? from,
    List<EmailAddress>? to,
    List<EmailAddress>? cc,
    String? preview,
    bool? isSeen,
    bool? isFlagged,
    bool? hasAttachment,
    String? threadId,
    String? messageId,
    String? inReplyTo,
    String? references,
    DateTime? snoozedUntil,
    String? snoozedFromMailboxPath,
    String? listUnsubscribeHeader,
  }) {
    return Email(
      id: id ?? this.id,
      accountId: accountId ?? this.accountId,
      mailboxPath: mailboxPath ?? this.mailboxPath,
      uid: uid ?? this.uid,
      subject: subject ?? this.subject,
      sentAt: sentAt ?? this.sentAt,
      receivedAt: receivedAt ?? this.receivedAt,
      from: from ?? this.from,
      to: to ?? this.to,
      cc: cc ?? this.cc,
      preview: preview ?? this.preview,
      isSeen: isSeen ?? this.isSeen,
      isFlagged: isFlagged ?? this.isFlagged,
      hasAttachment: hasAttachment ?? this.hasAttachment,
      threadId: threadId ?? this.threadId,
      messageId: messageId ?? this.messageId,
      inReplyTo: inReplyTo ?? this.inReplyTo,
      references: references ?? this.references,
      snoozedUntil: snoozedUntil ?? this.snoozedUntil,
      snoozedFromMailboxPath:
          snoozedFromMailboxPath ?? this.snoozedFromMailboxPath,
      listUnsubscribeHeader:
          listUnsubscribeHeader ?? this.listUnsubscribeHeader,
    );
  }
}

/// A group of related emails sharing the same thread.
class EmailThread {
  final String threadId;
  final String? subject;
  final List<EmailAddress> participants;
  final DateTime latestDate;
  final int messageCount;
  final bool hasUnread;
  final bool isFlagged;
  final String latestEmailId;
  final String? preview;
  final String accountId;
  final String mailboxPath;

  // All email IDs in this thread (oldest-first). Needed for batch operations.
  final List<String> emailIds;

  const EmailThread({
    required this.threadId,
    required this.subject,
    required this.participants,
    required this.latestDate,
    required this.messageCount,
    required this.hasUnread,
    required this.isFlagged,
    required this.latestEmailId,
    this.preview,
    required this.emailIds,
    required this.accountId,
    required this.mailboxPath,
  });

  /// Wraps a single [Email] as a one-message thread for uniform rendering.
  factory EmailThread.fromEmail(Email e) => EmailThread(
        threadId: e.threadId ?? e.id,
        subject: e.subject,
        participants: e.from,
        latestDate: e.sentAt ?? e.receivedAt,
        messageCount: 1,
        hasUnread: !e.isSeen,
        isFlagged: e.isFlagged,
        latestEmailId: e.id,
        preview: e.preview,
        emailIds: [e.id],
        accountId: e.accountId,
        mailboxPath: e.mailboxPath,
      );
}

class EmailAddress {
  final String? name;
  final String email;

  const EmailAddress({this.name, required this.email});

  factory EmailAddress.fromJson(Map<String, dynamic> json) {
    return EmailAddress(
      name: json['name'] as String?,
      email: json['email'] as String,
    );
  }

  Map<String, dynamic> toJson() {
    return {if (name != null) 'name': name, 'email': email};
  }

  @override
  String toString() => name != null ? '$name <$email>' : email;
}

class EmailHeader {
  final String name;
  final String value;

  const EmailHeader({required this.name, required this.value});

  factory EmailHeader.fromJson(Map<String, dynamic> json) {
    return EmailHeader(
      name: json['name'] as String,
      value: json['value'] as String,
    );
  }

  Map<String, dynamic> toJson() => {'name': name, 'value': value};
}

/// Full message body — fetched on demand, cached in the local DB.
class MimePart {
  final String contentType;
  final String? filename;
  final int? size;
  final String? encoding;
  final List<MimePart> children;

  const MimePart({
    required this.contentType,
    this.filename,
    this.size,
    this.encoding,
    this.children = const [],
  });
}

class EmailBody {
  final String emailId;
  final String? textBody;
  final String? htmlBody;
  final List<EmailAttachment> attachments;
  final List<EmailHeader> headers;
  final MimePart? mimeTree;

  const EmailBody({
    required this.emailId,
    this.textBody,
    this.htmlBody,
    required this.attachments,
    this.headers = const [],
    this.mimeTree,
  });
}

class EmailAttachment {
  final String filename;
  final String contentType;
  final int size;

  /// IMAP BODYSTRUCTURE part identifier (e.g. "2", "2.1") used for on-demand
  /// download. Empty for attachments cached before this field was added.
  final String fetchPartId;

  const EmailAttachment({
    required this.filename,
    required this.contentType,
    required this.size,
    this.fetchPartId = '',
  });
}

/// A pending local mutation (flag, move, delete) that has failed at least once
/// and may be stuck in the outbound queue.
class FailedMutation {
  final int id;
  final String accountId;

  /// "flag_seen" | "flag_flagged" | "move" | "delete"
  final String changeType;
  final String resourceId;
  final String lastError;
  final int attempts;
  final DateTime createdAt;

  const FailedMutation({
    required this.id,
    required this.accountId,
    required this.changeType,
    required this.resourceId,
    required this.lastError,
    required this.attempts,
    required this.createdAt,
  });
}

/// Outgoing email — used for compose / reply.
class EmailDraft {
  final EmailAddress from;
  final List<EmailAddress> to;
  final List<EmailAddress> cc;
  final String subject;
  final String body;

  /// Local file-system paths of files to attach when sending.
  final List<String> attachmentFilePaths;

  const EmailDraft({
    required this.from,
    required this.to,
    required this.cc,
    required this.subject,
    required this.body,
    this.attachmentFilePaths = const [],
  });
}

class SyncEmailsResult {
  const SyncEmailsResult({
    required this.fetched,
    required this.skipped,
    required this.bytesTransferred,
  });

  final int fetched;
  final int skipped;
  final int bytesTransferred;

  static const zero = SyncEmailsResult(
    fetched: 0,
    skipped: 0,
    bytesTransferred: 0,
  );

  SyncEmailsResult operator +(SyncEmailsResult other) => SyncEmailsResult(
        fetched: fetched + other.fetched,
        skipped: skipped + other.skipped,
        bytesTransferred: bytesTransferred + other.bytesTransferred,
      );
}

class ReliabilityResult {
  const ReliabilityResult({
    required this.missingLocally,
    required this.missingOnServer,
    required this.flagMismatches,
  });

  final List<String> missingLocally; // Server UIDs/IDs not in local DB
  final List<String> missingOnServer; // Local UIDs/IDs not on server
  final List<FlagMismatch> flagMismatches;

  bool get isHealthy =>
      missingLocally.isEmpty &&
      missingOnServer.isEmpty &&
      flagMismatches.isEmpty;

  static const healthy = ReliabilityResult(
    missingLocally: [],
    missingOnServer: [],
    flagMismatches: [],
  );
}

class FlagMismatch {
  const FlagMismatch({
    required this.id,
    required this.serverSeen,
    required this.localSeen,
    required this.serverFlagged,
    required this.localFlagged,
  });

  final String id;
  final bool serverSeen;
  final bool localSeen;
  final bool serverFlagged;
  final bool localFlagged;
}
