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sharedinbox/lib/core/sieve/sieve_interpreter.dart
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Dart

import 'package:sharedinbox/core/sieve/sieve_actions.dart';
import 'package:sharedinbox/core/sieve/sieve_conditions.dart';
import 'package:sharedinbox/core/sieve/sieve_rule.dart';
/// A lightweight email representation used by [SieveInterpreter].
/// Header names are lower-cased.
class SieveEmailContext {
const SieveEmailContext({required this.headers, this.sizeBytes = 0});
final Map<String, List<String>> headers;
final int sizeBytes;
List<String> getHeader(String name) =>
headers[name.toLowerCase()] ?? const [];
}
/// Tracks the outcome of running a Sieve script against one email.
class SieveExecutionContext {
bool isCancelled = false;
Set<String> targetFolders = {};
Set<String> flagsToAdd = {};
bool keepInInbox = true;
}
/// Evaluates a compiled list of [SieveRule]s against a [SieveEmailContext].
class SieveInterpreter {
/// Executes [rules] and returns the resulting [SieveExecutionContext].
///
/// Rules produced by [SieveParser] may carry a [SieveRule.branchGroupId]
/// to represent if/elsif/else chains; at most one branch per group fires.
SieveExecutionContext execute(
List<SieveRule> rules,
SieveEmailContext email,
) {
final ctx = SieveExecutionContext();
final firedGroups = <int>{};
for (final rule in rules) {
if (ctx.isCancelled) break;
final groupId = rule.branchGroupId;
if (groupId != null && firedGroups.contains(groupId)) continue;
bool matches;
if (rule.isElseBranch) {
matches = true; // else fires unconditionally (group not yet consumed)
} else {
matches = _evaluateConditions(rule, email);
}
if (matches) {
_applyActions(rule.actions, ctx);
if (groupId != null) firedGroups.add(groupId);
if (ctx.isCancelled) break;
}
}
// Implicit keep: if no fileinto/discard was reached, email stays in inbox.
return ctx;
}
bool _evaluateConditions(SieveRule rule, SieveEmailContext email) {
if (rule.conditions.isEmpty) return true;
return switch (rule.joinType) {
'allof' => rule.conditions.every((c) => _evalCondition(c, email)),
'anyof' => rule.conditions.any((c) => _evalCondition(c, email)),
_ => rule.conditions.length == 1 &&
_evalCondition(rule.conditions.first, email),
};
}
bool _evalCondition(SieveCondition cond, SieveEmailContext email) {
return switch (cond) {
final HeaderCondition c => _evalHeader(c, email),
final SizeCondition c => _evalSize(c, email),
};
}
bool _evalHeader(HeaderCondition cond, SieveEmailContext email) {
for (final header in cond.headers) {
final values = email.getHeader(header);
for (final value in values) {
for (final key in cond.keyList) {
if (_matchString(value, cond.matchType, key)) return true;
}
}
}
return false;
}
bool _evalSize(SizeCondition cond, SieveEmailContext email) {
return switch (cond.comparison) {
':over' => email.sizeBytes > cond.bytes,
':under' => email.sizeBytes < cond.bytes,
_ => false,
};
}
bool _matchString(String value, String matchType, String key) {
final v = value.toLowerCase();
final k = key.toLowerCase();
return switch (matchType) {
':contains' => k.isEmpty || v.contains(k),
':is' => v == k,
':matches' => _globMatch(v, k),
_ => false,
};
}
bool _globMatch(String value, String pattern) {
final regexStr = RegExp.escape(
pattern,
).replaceAll(r'\*', '.*').replaceAll(r'\?', '.');
return RegExp('^$regexStr\$').hasMatch(value);
}
void _applyActions(List<SieveAction> actions, SieveExecutionContext ctx) {
for (final action in actions) {
switch (action) {
case final FileIntoAction a:
ctx.targetFolders.add(a.folder);
ctx.keepInInbox = false;
case DiscardAction():
ctx.isCancelled = true;
ctx.keepInInbox = false;
return;
case KeepAction():
ctx.keepInInbox = true;
case MarkAsSeenAction():
ctx.flagsToAdd.add(r'\Seen');
case final FlagAction a:
ctx.flagsToAdd.addAll(a.flags);
}
}
}
}