From 0c89256c782f0d1e98e93047fa90ad90b4e003e3 Mon Sep 17 00:00:00 2001
From: Miquel Sabaté Solà <mssola@mssola.com>
Date: Wed, 14 Jan 2026 22:36:54 +0100
Subject: Touch the 'updated_at' column on exercise success
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If the user runs into an exercise and is satisfied with the results,
then touch the 'updated_at' column for that exercise. This is relevant
because in practice exercises are selected by the lastly updated
exercise.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>
---
 crates/cli/src/run.rs | 10 +++++++---
 lib/mihi/src/lib.rs   | 19 +++++++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/crates/cli/src/run.rs b/crates/cli/src/run.rs
index 744fe6f..bbfa6bc 100644
--- a/crates/cli/src/run.rs
+++ b/crates/cli/src/run.rs
@@ -1,4 +1,5 @@
 use inquire::{Confirm, Editor, Text};
+use mihi::touch_exercise;
 use mihi::{select_relevant_words, update_success, Category, Exercise, ExerciseKind, Word};
 use std::env;
 use std::fs;
@@ -124,7 +125,7 @@ fn diff_tool() -> Option<&'static str> {
 // and interactively ask the user if things are ok. Returns a boolean depending
 // on the user's answer to that final question, or false if something went
 // wrong.
-fn accepted_diff(given: String, expected: String) -> bool {
+fn accepted_diff(given: String, expected: &String) -> bool {
     // If a diff tool could be fetched, then write into temporary files and call
     // the diff tool against both temporary files; otherwise just print things
     // out into the stdout.
@@ -192,8 +193,11 @@ fn run_exercises(exercises: Vec<Exercise>) -> bool {
             exercise.title, exercise.enunciate
         );
 
-        if !accepted_diff(solution, exercise.solution) {
-            // TODO: update_{success,failure}
+        // If the exercise is seen as correct by the user, then "touch"
+        // (i.e. refresh the 'updated_at' date). This way, next time we select
+        // exercises to show the user, we can prevent this one showing up first.
+        if accepted_diff(solution, &exercise.solution) {
+            let _ = touch_exercise(exercise);
         }
     }
 
diff --git a/lib/mihi/src/lib.rs b/lib/mihi/src/lib.rs
index 2915368..4d337b9 100644
--- a/lib/mihi/src/lib.rs
+++ b/lib/mihi/src/lib.rs
@@ -856,6 +856,25 @@ pub fn update_exercise(exercise: Exercise) -> Result<(), String> {
     }
 }
 
+/// Updates the 'updated_at' column for an exercise.
+pub fn touch_exercise(exercise: Exercise) -> Result<(), String> {
+    if exercise.id == 0 {
+        return Err("invalid exercise to update; seems it has not been created before".to_string());
+    }
+
+    let conn = get_connection()?;
+
+    match conn.execute(
+        "UPDATE exercises \
+         SET updated_at = datetime('now') \
+         WHERE id = ?1",
+        params![exercise.id],
+    ) {
+        Ok(_) => Ok(()),
+        Err(e) => Err(format!("could not update '{}': {}", exercise.title, e)),
+    }
+}
+
 /// Delete an exercise from the database.
 pub fn delete_exercise(title: &str) -> Result<(), String> {
     let conn = get_connection()?;
-- 
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