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|
use lastfm;
use failure::Fail;
const SCHEMA: &'static str = "
CREATE TABLE `tracks` (
artist varchar(1024) NOT NULL,
album varchar(1024) DEFAULT NULL,
name varchar(1024) NOT NULL,
timestamp integer(11) NOT NULL
);
";
pub struct DB {
conn: rusqlite::Connection,
}
impl DB {
pub fn new<P: AsRef<std::path::Path>>(path: &P) -> failure::Fallible<DB> {
let conn = if path.as_ref().exists() {
rusqlite::Connection::open(path)
.map_err(|e| {
let msg = format!(
"couldn't open db at {}",
path.as_ref().display()
);
e.context(msg)
})?
}
else {
Self::create(path)?
};
return Ok(DB { conn })
}
fn create<P: AsRef<std::path::Path>>(
path: &P
) -> failure::Fallible<rusqlite::Connection> {
eprintln!(
"Initializing database at {}",
path.as_ref().to_string_lossy(),
);
if let Some(parent) = path.as_ref().parent() {
std::fs::create_dir_all(parent)?;
let conn = rusqlite::Connection::open(path)
.map_err(|e| {
let msg = format!(
"couldn't create db at {}",
path.as_ref().display()
);
e.context(msg)
})?;
conn.execute(SCHEMA, rusqlite::NO_PARAMS)
.map_err(|e| e.context("failed to execute schema"))?;
Ok(conn)
}
else {
unimplemented!();
}
}
pub fn most_recent_timestamp(&self) -> failure::Fallible<Option<i64>> {
Ok(self.conn.query_row(
"SELECT timestamp FROM tracks ORDER BY timestamp DESC LIMIT 1",
rusqlite::NO_PARAMS,
|row| Some(row.get(0))
).or_else(|e| {
match e {
rusqlite::Error::QueryReturnedNoRows => Ok(None),
_ => Err(e),
}
})?)
}
pub fn insert_tracks(
&self,
tracks: impl Iterator<Item=lastfm::Track>,
) -> failure::Fallible<()> {
let mut sth = self.conn.prepare("INSERT INTO tracks VALUES (?, ?, ?, ?)")?;
for track in tracks {
sth.execute(
&[
&track.artist as &rusqlite::types::ToSql,
&track.album,
&track.name,
&track.timestamp,
]).map(|_| ())?;
}
Ok(())
}
pub fn query<F: Fn(&rusqlite::Row)>(
&self,
query: &str,
f: F
) -> failure::Fallible<Vec<String>> {
let mut sth = self.conn.prepare(query)?;
let cols = sth.column_names()
.iter()
.map(|s| s.to_string())
.collect();
let rows = sth.query_and_then(
rusqlite::NO_PARAMS,
|row| { f(row); Ok(()) },
)?;
// this call to collect() forces it to actually consume the iterator
// (and therefore call the callbacks). what i really want here is for
// there to be a query_for_each or something like that, but the weird
// way lifetimes work for rows makes it difficult to emulate this any
// other way
let errs: failure::Fallible<Vec<()>> = rows.collect();
errs.map(|_| cols)
}
}
|
