1 files changed, 160 insertions, 1 deletions
diff --git a/src/db/mod.rs b/src/db/mod.rs
index dec1023..f59aad5 100644
--- a/src/db/mod.rs
+++ b/src/db/mod.rs
@@ -1 +1,160 @@
-pub mod db;
+use crate::{
+    model::{card::Card, entry::Entry},
+    space_repetition,
+    util::serialization,
+};
+use anyhow::Result;
+use rusqlite::{params, Connection};
+use rusqlite_migration::{Migrations, M};
+
+use crate::util::time;
+
+pub fn init(database: String) -> Result<Connection> {
+    let mut conn = Connection::open(database)?;
+    let migrations = Migrations::new(vec![
+        M::up(include_str!("sql/1-init.sql")),
+        M::up(include_str!("sql/2-primary-key-question-responses.sql")),
+    ]);
+    migrations.to_latest(&mut conn)?;
+    Ok(conn)
+}
+
+pub fn last_deck_read(conn: &Connection) -> Option<u64> {
+    let mut stmt = conn
+        .prepare("SELECT deck_read FROM cards ORDER BY deck_read DESC LIMIT 1")
+        .ok()?;
+
+    let mut rows = stmt.query([]).ok()?;
+    let row = rows.next().ok()??;
+    row.get(0).ok()?
+}
+
+/// Synchronize the DB with the deck:
+///
+/// - insert new cards,
+/// - keep existing cards,
+/// - hide unused cards (keep state in case the card is added back afterward).
+pub fn synchronize(conn: &Connection, entries: Vec<Entry>) -> Result<()> {
+    let now = time::seconds_since_unix_epoch()?;
+
+    let state = serde_json::to_string(&space_repetition::init())?;
+
+    for entry in entries {
+        let concat_1 = serialization::words_to_line(&entry.part_1);
+        let concat_2 = serialization::words_to_line(&entry.part_2);
+
+        for w in entry.part_1.iter() {
+            insert(conn, now, w, &concat_2, &state)?;
+        }
+
+        for w in entry.part_2.iter() {
+            insert(conn, now, w, &concat_1, &state)?;
+        }
+    }
+
+    delete_read_before(conn, now)?;
+
+    Ok(())
+}
+
+fn insert(
+    conn: &Connection,
+    now: u64,
+    question: &str,
+    responses: &str,
+    state: &str,
+) -> Result<()> {
+    conn.execute(
+        "
+        INSERT INTO cards (question, responses, state, created, deck_read, ready)
+        VALUES (?, ?, ?, ?, ?, ?)
+        ON CONFLICT (question, responses) DO UPDATE SET deck_read = ?, deleted = null
+        ",
+        params![question, responses, state, now, now, now, now],
+    )?;
+
+    Ok(())
+}
+
+fn delete_read_before(conn: &Connection, t: u64) -> Result<()> {
+    conn.execute(
+        "UPDATE cards SET deleted = ? WHERE deck_read < ?",
+        params![t, t],
+    )?;
+
+    Ok(())
+}
+
+pub fn pick_random_ready(conn: &Connection) -> Option<Card> {
+    let now = time::seconds_since_unix_epoch().ok()?;
+
+    let mut stmt = conn
+        .prepare(
+            "
+        SELECT question, responses, state, ready
+        FROM cards
+        WHERE deleted IS NULL AND ready <= ?
+        ORDER BY RANDOM()
+        LIMIT 1
+        ",
+        )
+        .ok()?;
+
+    let mut rows = stmt.query([now]).ok()?;
+    let row = rows.next().ok()??;
+    let state_str: String = row.get(2).ok()?;
+    let responses_str: String = row.get(1).ok()?;
+
+    Some(Card {
+        question: row.get(0).ok()?,
+        responses: serialization::line_to_words(&responses_str),
+        state: serde_json::from_str(&state_str).ok()?,
+        ready: row.get(3).ok()?,
+    })
+}
+
+pub fn next_ready(conn: &Connection) -> Option<u64> {
+    let mut stmt = conn
+        .prepare(
+            "
+        SELECT ready 
+        FROM cards 
+        WHERE deleted IS NULL
+        ORDER BY ready
+        LIMIT 1
+    ",
+        )
+        .ok()?;
+
+    let mut rows = stmt.query([]).ok()?;
+    let row = rows.next().ok()??;
+    row.get(0).ok()?
+}
+
+pub fn count_available(conn: &Connection) -> Option<i32> {
+    let now = time::seconds_since_unix_epoch().ok()?;
+    let mut stmt = conn
+        .prepare("SELECT COUNT(*) FROM cards WHERE ready <= ? AND deleted IS NULL")
+        .ok()?;
+
+    let mut rows = stmt.query([now]).ok()?;
+    let row = rows.next().ok()??;
+    row.get(0).ok()?
+}
+
+pub fn update(conn: &Connection, question: &str, state: &space_repetition::State) -> Result<()> {
+    let now = time::seconds_since_unix_epoch()?;
+    let ready = now + state.get_interval_seconds();
+    let state_str = serde_json::to_string(state)?;
+
+    conn.execute(
+        "
+        UPDATE cards
+        SET state = ?, updated = ?, ready = ?
+        WHERE question = ?
+        ",
+        params![state_str, now, ready, question],
+    )?;
+
+    Ok(())
+}