feat: hashed_text fns

schema/000_extensions.sql

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+create extension pgcrypto;

schema/000_hashed_text.sql

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-create type hashed_text as (hashed text);

schema/010_hashed_text.sql

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+create type hashed_text as (hashed text);
+
+create function hashed_text_string(hashed hashed_text)
+  returns text
+  language sql
+  immutable
+  as 'select (hashed.hashed);';
+
+create function hash_text(plain text)
+  returns hashed_text
+  language plpgsql
+  immutable
+  as $$
+begin
+  return row(crypt(plain, gen_salt('bf')));
+end;
+$$;
+
+create function hashed_text_matches(plain text, hashed hashed_text)
+  returns boolean
+  language plpgsql
+  immutable
+  as $$
+begin
+ return hashed_text_string(hashed) = crypt(plain, hashed_text_string(hashed));
+end;
+$$;