Purchaser: Add `generate_secret()` method

This new method generates a secret, which is a SHA1 digest of the
purchaser's name, email, and a random integer.

In order to use the `hexdigest()` method in the 'sha1' crate, I needed
to add the feature `std`
(https://docs.rs/sha1/0.6.0/sha1/struct.Sha1.html#method.hexdigest).

Needed to change the `secret` field to a `String` because otherwise the
generated digest string doesn't have a long enough lifetime to assign to
it.

Update `with_secret()` to use the new `String` type.

Update `insert()` to correctly handle the `Option` in `secret`.

3 files changed, 37 insertions, 9 deletions

diff --git a/license-generator/Cargo.lock b/license-generator/Cargo.lock
index 733d2c9..9510eb7 100644
--- a/license-generator/Cargo.lock
+++ b/license-generator/Cargo.lock
@@ -285,6 +285,8 @@ dependencies = [
  "error-chain 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "fastcgi 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "mysql 14.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sha1 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
diff --git a/license-generator/Cargo.toml b/license-generator/Cargo.toml
index d031794..89b54fa 100644
--- a/license-generator/Cargo.toml
+++ b/license-generator/Cargo.toml
@@ -6,6 +6,8 @@ version = "0.0.1"
 error-chain = "0.12.0"
 fastcgi = "1.0.0"
 mysql = "14.1.1"
+rand = "0.5.5"
+sha1 = { version = "0.6.0", features = ["std"] }
 
 [workspace]
 members = [
diff --git a/license-generator/src/lib.rs b/license-generator/src/lib.rs
index 9f73f6b..cc39cdb 100644
--- a/license-generator/src/lib.rs
+++ b/license-generator/src/lib.rs
@@ -1,6 +1,8 @@
 #[macro_use]
 extern crate error_chain;
 extern crate mysql;
+extern crate rand;
+extern crate sha1;
 
 mod errors {
     use mysql;
@@ -17,7 +19,7 @@ use errors::*;
 struct Purchaser<'a> {
     name: &'a str,
     email: &'a str,
-    secret: Option<&'a str>,
+    secret: Option<String>,
 }
 
 impl<'a> Purchaser<'a> {
@@ -29,11 +31,20 @@ impl<'a> Purchaser<'a> {
         }
     }
 
-    fn with_secret(mut self, secret: &'a str) -> Self {
+    fn with_secret(mut self, secret: String) -> Self {
         self.secret = Some(secret);
         self
     }
 
+    fn generate_secret(&mut self) {
+        let random: usize = rand::random();
+
+        let source = format!("{}{}{}", self.name, self.email, random);
+        let digest = sha1::Sha1::from(source).hexdigest();
+
+        self.secret = Some(digest);
+    }
+
     fn insert(&self, cx: &mut mysql::Conn) -> Result<()> {
         let mut tx = cx.start_transaction(
             false,  // consistent_snapshot
@@ -41,13 +52,26 @@ impl<'a> Purchaser<'a> {
             None,   // readonly
         )?;
 
-        tx.prep_exec("
-            INSERT INTO purchasers
-                (name, email, secret)
-                VALUES
-                (?, ?, ?)",
-            (self.name, self.email, self.secret),
-        )?;
+        match self.secret {
+            Some(ref s) => {
+                tx.prep_exec("
+                    INSERT INTO purchasers
+                        (name, email, secret)
+                        VALUES
+                        (?, ?, ?)",
+                    (self.name, self.email, s),
+                )?;
+            },
+            None => {
+                tx.prep_exec("
+                    INSERT INTO purchasers
+                        (name, email)
+                        VALUES
+                        (?, ?)",
+                    (self.name, self.email),
+                )?;
+            },
+        }
 
         Ok(())
     }