MONGOCRYPT-821 text indexes for explicit encryption (#1037)

* Support explicit encryption for algorithm type: `textPreview` and query types `prefixPreview`, `suffixPreview` and `substringPreview`
* Add `mongocrypt_setopt_algorithm_text`.

Author: mdb-ad

CMakeLists.txt

@@ -121,6 +121,7 @@ set (MONGOCRYPT_SOURCES
    src/mc-range-mincover.c
    src/mc-range-encoding.c
    src/mc-rangeopts.c
+   src/mc-textopts.c
    src/mc-reader.c
    src/mc-schema-broker.c
    src/mc-str-encode-string-sets.c
@@ -483,6 +484,7 @@ set (TEST_MONGOCRYPT_SOURCES
    test/test-mc-range-edge-generation.c
    test/test-mc-range-mincover.c
    test/test-mc-rangeopts.c
+   test/test-mc-textopts.c
    test/test-mc-reader.c
    test/test-mc-text-search-str-encode.c
    test/test-mc-schema-broker.c

src/mc-textopts-private.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2025-present MongoDB, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MC_TEXTOPTS_PRIVATE_H
+#define MC_TEXTOPTS_PRIVATE_H
+
+#include <bson/bson.h>
+
+#include "mc-optional-private.h"
+#include "mongocrypt-private.h"
+
+typedef struct {
+    bool set;
+    mc_optional_int32_t strMaxLength;
+    int32_t strMinQueryLength;
+    int32_t strMaxQueryLength;
+} mc_TextOptsPerIndex_t;
+
+typedef struct {
+    mc_TextOptsPerIndex_t substring;
+    mc_TextOptsPerIndex_t prefix;
+    mc_TextOptsPerIndex_t suffix;
+
+    bool caseSensitive;
+    bool diacriticSensitive;
+} mc_TextOpts_t;
+
+/* mc_TextOpts_parse parses a BSON document into mc_TextOpts_t.
+ * The document is expected to have the form:
+ * {
+ *   "caseSensitive": bool,
+ * . "diacriticSensitive": bool,
+ * . "prefix": {
+ * .   "strMaxQueryLength": Int32,
+ * .   "strMinQueryLength": Int32,
+ * . },
+ * . "suffix": {
+ * .   "strMaxQueryLength": Int32,
+ * .   "strMinQueryLength": Int32,
+ * . },
+ * . "substring": {
+ * .   "strMaxLength": Int32,
+ * .   "strMaxQueryLength": Int32,
+ * .   "strMinQueryLength": Int32,
+ * . },
+ * }
+ */
+bool mc_TextOpts_parse(mc_TextOpts_t *txo, const bson_t *in, mongocrypt_status_t *status);
+
+/*
+ * mc_TextOpts_to_FLE2TextSearchInsertSpec creates a placeholder value to be
+ * encrypted. It is only expected to be called when query_type is unset. The
+ * output FLE2TextSearchInsertSpec is a BSON document of the form:
+ * https://github.com/mongodb/mongo/blob/219e90bfad3c712c9642da29ee52229908f06bcd/src/mongo/crypto/fle_field_schema.idl#L689
+ *
+ * v is expect to be a BSON document of the form:
+ * { "v": BSON value to encrypt }.
+ *
+ * Preconditions: out must be initialized by caller.
+ */
+bool mc_TextOpts_to_FLE2TextSearchInsertSpec(const mc_TextOpts_t *txo,
+                                             const bson_t *v,
+                                             bson_t *out,
+                                             mongocrypt_status_t *status);
+
+#endif // MC_TEXTOPTS_PRIVATE_H