Scheduling

1 files changed, 219 insertions, 16 deletions

diff --git a/script.js b/script.js
index d6f3415..d2004ad 100644
--- a/script.js
+++ b/script.js
@@ -1,3 +1,122 @@
+function reportException(e) {
+  const error = e instanceof Error ? e : new Error(e.toString());
+  console.log(JSON.stringify(error.stack));
+  showToast(`An error has occurred!\n\n${error}\n\n${error.stack}`);
+}
+
+/***********************************************************************
+ * Actual FSRS5 algorithm                                              *
+ ***********************************************************************/
+
+const W = [
+  0.40255, 1.18385, 3.173, 15.69105, 7.1949, 0.5345, 1.4604, 0.0046, 1.54575, 0.1192, 1.01925,
+  1.9395, 0.11, 0.29605, 2.2698, 0.2315, 2.9898, 0.51655, 0.6621,
+];
+
+const F = 19.0 / 81.0;
+const C = -0.5;
+
+const Grade = {
+  forgot: 1.0,
+  hard: 2.0,
+  good: 3.0,
+  easy: 4.0
+};
+
+function retrievability(t, s) {
+  return Math.pow(1.0 + F * (t / s), C);
+}
+
+function interval(r_d, s) {
+  return (s / F) * (Math.pow(r_d, 1.0 / C) - 1.0);
+}
+
+function s_0(g) {
+  switch (g) {
+  case Grade.forgot: return W[0];
+  case Grade.hard: return W[1];
+  case Grade.good: return W[2];
+  case Grade.easy: return W[3];
+  }
+}
+
+function s_success(d, s, r, g) {
+  const t_d = 11.0 - d;
+  const t_s = Math.pow(s, -W[9]);
+  const t_r = Math.exp(W[10] * (1.0 - r)) - 1.0;
+  const h = g === Grade.hard ? W[15] : 1.0;
+  const b = g === Grade.easy ? W[16] : 1.0;
+  const c = Math.exp(W[8]);
+  const alpha = 1.0 + t_d * t_s * t_r * h * b * c;
+  return s * alpha;
+}
+
+function s_fail(d, s, r) {
+  const d_f = Math.pow(d, -W[12]);
+  const s_f = Math.pow(s + 1.0, W[13]) - 1.0;
+  const r_f = Math.exp(W[14] * (1.0 - r));
+  const c_f = W[11];
+  const result = d_f * s_f * r_f * c_f;
+  return Math.min(result, s);
+}
+
+function stability(d, s, r, g) {
+  return g === Grade.forgot ? s_fail(d, s, r) : s_success(d, s, r, g);
+}
+
+function clamp_d(d) {
+  return Math.min(10.0, Math.max(1.0, d));
+}
+
+function d_0(g) {
+  const g_value = Grade[g];
+  return clamp_d(W[4] - Math.exp(W[5] * (g_value - 1.0)) + 1.0);
+}
+
+function difficulty(d, g) {
+  return clamp_d(W[7] * d_0('easy') + (1.0 - W[7]) * dp(d, g));
+}
+
+function dp(d, g) {
+  return d + delta_d(g) * ((10.0 - d) / 9.0);
+}
+
+function delta_d(g) {
+  const g_value = Grade[g];
+  return -W[6] * (g_value - 3.0);
+}
+
+function sim(grades) {
+  let t = 0.0;
+  const r_d = 0.9;
+  const steps = [];
+
+  // Initial review
+  if (grades.length === 0) {
+    throw new Error("Grades cannot be empty");
+  }
+
+  let gradesCopy = [...grades];
+  let g = gradesCopy.shift(); // Remove the first grade
+  let s = s_0(g);
+  let d = d_0(g);
+  let i = Math.max(Math.round(interval(r_d, s)), 1.0);
+
+  steps.push({ t, s, d, i });
+
+  // n-th review
+  for (let g of gradesCopy) {
+    t += i;
+    const r = retrievability(i, s);
+    s = stability(d, s, r, g);
+    d = difficulty(d, g);
+    i = Math.max(Math.round(interval(r_d, s)), 1.0);
+    steps.push({ t, s, d, i });
+  }
+
+  return steps;
+}
+
 /***********************************************************************
  * State file processing                                               *
  ***********************************************************************/
@@ -22,6 +141,10 @@ function loadCard(card) {
 }
 
 function flipCard() {
+  if (window.index >= window.cards.length) {
+    return;
+  }
+  
   window.card.revealed = true;
 
   // Reveal the "back".
@@ -37,26 +160,105 @@ function flipCard() {
   window.buttons.style.display = "flex";
 }
 
+function endReview() {
+  clearInterval(window.updateInterval);
+  window.statusInfo.innerHTML = "Session complete!";
+  window.flashcard.style.display = "none";
+  window.buttons.style.display = "none";
+
+  // TODO: Update cards.
+}
+
 function rateCard(difficulty) {
   if (!window.card.revealed) {
     return;
   }
-  // if (difficulty === "forgot") {
 
-  // }
-  if (++window.index < window.cards.length) {
+  const card = window.cards[window.index];
+
+  const r_d = 0.9;
+  const s = card.s;
+  const d = card.d;
+  const i = card.i;
+  const g = card.flagged ? Grade.forgot : Grade[difficulty];
+
+  let s_n = undefined, d_n = undefined, i_n = undefined;
+
+  if (s == null || d == null || i == null) {
+    s_n = s_0(g);
+    d_n = d_0(g);
+  } else {
+    const r = retrievability(i, s);
+    s_n = stability(d, s, r, g);
+    d_n = difficulty(d, g);
+  }
+  i_n = Math.max(Math.round(interval(r_d, s)), 1.0);
+
+  const scheduled = new Date(card.scheduled);
+  scheduled.setDate(scheduled + i);
+
+  if (difficulty === "forgot") {
+    // Shift forgotten card to end.
+    window.cards.push(card);
+    window.cards.splice(window.index, 1);
     loadCard(window.cards[window.index]);
   } else {
-    clearInterval(window.updateInterval);
-    window.statusInfo.innerHTML = "Session complete!";
-    window.flashcard.style.display = "none";
-    window.buttons.style.display = "none";
+    // Unflag and update scheduler parameters.
+    delete card.flagged;
+    card.s = s_n;
+    card.d = d_n;
+    card.i = i_n;
+
+    if (++window.index < window.cards.length) {
+      loadCard(window.cards[window.index]);
+    } else {
+      endReview();
+    }
+  }
+}
+
+// Update `window.allCards` with new scheduler parameters.
+function updateAllCards() {
+  for (let i = 0; i < window.allCards.length; i++) {
+    const updated = window.cards.find((card) => card.id == window.allCards[i].id);
+    if (updated) {
+      window.allCards[i] = updated;
+    }
   }
 }
 
-// Todo: check if card is revealed before allowing button inpt.
+function today() {
+  let today = new Date();
+  today.setHours(0, 0, 0, 0);
+  return today;
+}
+
+function checkCards(cards) {
+  for (let i = 0; i < cards.length; i++) {
+    const card = cards[i];
+    if (!card.id) {
+      throw new Error("malformed card: missing id")
+    } else if (!card.front) {
+      throw new Error(`malformed card ${card.id}: missing front`)
+    } else if (!card.back) {
+      throw new Error(`malformed card ${card.id}: missing bacak`)
+    }
+    if (!card.scheduled) {
+      card.scheduled = today().toJSON();
+    }
+    if (!card.scheduler) {
+      card.scheduler = {
+        s: null,
+        d: null,
+        i: null
+      }
+    }
+  }
+}
 
 function loadCards(data) {
+  checkCards(data);
+
   document.getElementById('flashcard').style.display = "block";
 
   window.allCards = data;
@@ -73,8 +275,8 @@ function loadCards(data) {
     .addEventListener('click', () => rateCard('forgot'));
   document.getElementById('rating-button-hard')
     .addEventListener('click', () => rateCard('hard'));
-  document.getElementById('rating-button-medium')
-    .addEventListener('click', () => rateCard('medium'));
+  document.getElementById('rating-button-good')
+    .addEventListener('click', () => rateCard('good'));
   document.getElementById('rating-button-easy')
     .addEventListener('click', () => rateCard('easy'));
 
@@ -85,7 +287,6 @@ function loadCards(data) {
     return (new Date(card.scheduled)) <= today;
   });
 
-  // Temporary
   loadCard(window.cards[0]);
 
   window.updateInterval = setInterval(() => {
@@ -99,7 +300,7 @@ function loadCards(data) {
 
 function showToast(message, duration = 3000) {
   const toast = document.getElementById("toast");
-  toast.textContent = message;
+  toast.innerHTML = "<pre>" + message + "</pre>";
 
   // Show the toast
   toast.classList.add("show");
@@ -111,6 +312,7 @@ function showToast(message, duration = 3000) {
 }
 
 window.addEventListener("load", (event) => {
+
   document.getElementById('cards-input').addEventListener('change', function(event) {
     const file = event.target.files[0];
     if (!file) return;
@@ -120,18 +322,19 @@ window.addEventListener("load", (event) => {
       try {
         const content = e.target.result;
         loadCards(JSON.parse(content));
-      } catch (error) {
-        console.error("JSON Parsing Error:", error);
+      } catch (e) {
+        reportException(e);
       }
     };
 
     reader.onerror = function(error) {
       document.getElementById('result').textContent = "Error reading file: " + error;
-      console.error("File Reading Error:", error);
+      reportException(error);
     };
 
     reader.readAsText(file); // Read the file as text
   });
+
 });
 
 window.addEventListener('keydown', (event) => {
@@ -143,7 +346,7 @@ window.addEventListener('keydown', (event) => {
   } else if (event.code === 'Digit2' || event.code === "Numpad2") {
     rateCard('easy')
   } else if (event.code === 'Digit3' || event.code === "Numpad3") {
-    rateCard('medium')
+    rateCard('good')
   } else if (event.code === 'Digit4' || event.code === "Numpad4") {
     rateCard('hard')
   }