add spaced repetition system (SRS) models, engine, and word selector logic

src/greek_lang/srs/engine.py

@@ -0,0 +1,24 @@
+from datetime import datetime, timedelta
+
+from .models import UserWordProgress, ReviewState
+
+
+def sm2_update(p: UserWordProgress, grade: int, now: datetime) -> None:
+    # grade: 0..5
+    e = p.ease + (0.1 - (5 - grade) * (0.08 + (5 - grade) * 0.02))
+    p.ease = max(1.3, e)
+    if grade < 3:
+        p.interval_days = 1
+        p.reps = 0
+        p.lrn_step = 0
+        p.state = ReviewState.lapsed
+    else:
+        if p.reps == 0:
+            p.interval_days = 1
+        elif p.reps == 1:
+            p.interval_days = 6
+        else:
+            p.interval_days = round(p.interval_days * p.ease)
+        p.reps += 1
+        p.state = ReviewState.review
+    p.due_at = now + timedelta(days=p.interval_days)

src/greek_lang/srs/models.py

@@ -0,0 +1,66 @@
+import enum
+import datetime as dt
+
+from sqlalchemy import (
+    BigInteger,
+    Integer,
+    Float,
+    DateTime,
+    Enum,
+    ForeignKey,
+    UniqueConstraint,
+    func,
+)
+from sqlalchemy.orm import Mapped, mapped_column
+
+from greek_lang.database.base import Base
+
+
+class ReviewState(enum.StrEnum):
+    learning = "learning"
+    review = "review"
+    lapsed = "lapsed"
+
+
+class UserWordProgress(Base):
+    __tablename__ = "srs_progress"
+    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
+    user_id: Mapped[int] = mapped_column(
+        ForeignKey("users.id"), index=True, nullable=False
+    )
+    word_id: Mapped[int] = mapped_column(
+        ForeignKey("glossary_word.id"), index=True, nullable=False
+    )
+    due_at: Mapped[dt.datetime] = mapped_column(
+        DateTime(timezone=True), index=True, server_default=func.now(), nullable=False
+    )
+    interval_days: Mapped[int] = mapped_column(Integer, nullable=False, default=1)
+    ease: Mapped[float] = mapped_column(Float, nullable=False, default=2.5)
+    reps: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    lrn_step: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    state: Mapped[ReviewState] = mapped_column(
+        Enum(ReviewState, native_enum=False),
+        nullable=False,
+        default=ReviewState.learning,
+    )
+
+    __table_args__ = (UniqueConstraint("user_id", "word_id", name="uq_srs_user_word"),)
+
+
+class ReviewLog(Base):
+    __tablename__ = "srs_review_log"
+    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
+    user_id: Mapped[int] = mapped_column(
+        ForeignKey("users.id"), index=True, nullable=False
+    )
+    word_id: Mapped[int] = mapped_column(
+        ForeignKey("glossary_word.id"), index=True, nullable=False
+    )
+    ts: Mapped[dt.datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    grade: Mapped[int] = mapped_column(Integer, nullable=False)  # 0..5
+    prev_interval: Mapped[int] = mapped_column(Integer, nullable=False)
+    new_interval: Mapped[int] = mapped_column(Integer, nullable=False)
+    prev_ease: Mapped[float] = mapped_column(Float, nullable=False)
+    new_ease: Mapped[float] = mapped_column(Float, nullable=False)

src/greek_lang/srs/selector.py

@@ -0,0 +1,28 @@
+from collections.abc import Sequence
+
+from sqlalchemy import select, func
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from greek_lang.glossaries.models import GlossaryWord
+
+from .models import UserWordProgress
+
+
+async def pick_due_words(
+    db: AsyncSession,
+    user_id: int,
+    limit: int = 10,
+) -> Sequence[tuple[GlossaryWord, UserWordProgress]]:
+    stmt = (
+        select(GlossaryWord, UserWordProgress)
+        .join(UserWordProgress, UserWordProgress.word_id == GlossaryWord.id)
+        .where(
+            UserWordProgress.user_id == user_id,
+            UserWordProgress.due_at <= func.now(),
+        )
+        .order_by(UserWordProgress.due_at)
+        .limit(limit)
+    )
+
+    result = await db.execute(stmt)
+    return result.tuples().all()

src/greek_lang/translator.py

@@ -28,7 +28,7 @@ async def translate(
         source_lang=source_lang,
         target_lang=target_lang,
     )
-    pronon = await get_pronunciation(text="έμπορος", source_lang=source_lang)
+    pronon = await get_pronunciation(text=word_response.lemma, source_lang=source_lang)
 
     async with db_session_maker() as db_session, db_session.begin():
         values = {