use rusqlite::Connection;
use rusqlite::OptionalExtension;

use crate::core::backoff::compute_next_attempt_at;
use crate::core::error::Result;
use crate::core::time::now_ms;
use crate::documents::SourceType;

const DIRTY_SOURCES_BATCH_SIZE: usize = 500;

pub fn mark_dirty_tx(
    tx: &rusqlite::Transaction<'_>,
    source_type: SourceType,
    source_id: i64,
) -> Result<()> {
    tx.execute(
        "INSERT INTO dirty_sources (source_type, source_id, queued_at)
         VALUES (?1, ?2, ?3)
         ON CONFLICT(source_type, source_id) DO UPDATE SET
           queued_at = excluded.queued_at,
           attempt_count = 0,
           last_attempt_at = NULL,
           last_error = NULL,
           next_attempt_at = NULL",
        rusqlite::params![source_type.as_str(), source_id, now_ms()],
    )?;
    Ok(())
}

pub fn mark_dirty(conn: &Connection, source_type: SourceType, source_id: i64) -> Result<()> {
    conn.execute(
        "INSERT INTO dirty_sources (source_type, source_id, queued_at)
         VALUES (?1, ?2, ?3)
         ON CONFLICT(source_type, source_id) DO UPDATE SET
           queued_at = excluded.queued_at,
           attempt_count = 0,
           last_attempt_at = NULL,
           last_error = NULL,
           next_attempt_at = NULL",
        rusqlite::params![source_type.as_str(), source_id, now_ms()],
    )?;
    Ok(())
}

pub fn get_dirty_sources(conn: &Connection) -> Result<Vec<(SourceType, i64)>> {
    let now = now_ms();
    let mut stmt = conn.prepare(
        "SELECT source_type, source_id FROM dirty_sources
         WHERE next_attempt_at IS NULL OR next_attempt_at <= ?1
         ORDER BY attempt_count ASC, queued_at ASC
         LIMIT ?2",
    )?;
    let rows = stmt
        .query_map(
            rusqlite::params![now, DIRTY_SOURCES_BATCH_SIZE as i64],
            |row| {
                let st_str: String = row.get(0)?;
                let source_id: i64 = row.get(1)?;
                Ok((st_str, source_id))
            },
        )?
        .collect::<std::result::Result<Vec<_>, _>>()?;

    let mut results = Vec::with_capacity(rows.len());
    for (st_str, source_id) in rows {
        let source_type = SourceType::parse(&st_str).ok_or_else(|| {
            crate::core::error::LoreError::Other(format!(
                "Invalid source_type in dirty_sources: {}",
                st_str
            ))
        })?;
        results.push((source_type, source_id));
    }
    Ok(results)
}

pub fn clear_dirty(conn: &Connection, source_type: SourceType, source_id: i64) -> Result<()> {
    conn.execute(
        "DELETE FROM dirty_sources WHERE source_type = ?1 AND source_id = ?2",
        rusqlite::params![source_type.as_str(), source_id],
    )?;
    Ok(())
}

pub fn record_dirty_error(
    conn: &Connection,
    source_type: SourceType,
    source_id: i64,
    error: &str,
) -> Result<()> {
    let now = now_ms();
    let attempt_count: Option<i64> = conn
        .query_row(
            "SELECT attempt_count FROM dirty_sources WHERE source_type = ?1 AND source_id = ?2",
            rusqlite::params![source_type.as_str(), source_id],
            |row| row.get(0),
        )
        .optional()?;

    let Some(attempt_count) = attempt_count else {
        return Ok(());
    };

    let new_attempt = attempt_count + 1;
    let next_at = compute_next_attempt_at(now, new_attempt);

    conn.execute(
        "UPDATE dirty_sources SET
           attempt_count = ?1,
           last_attempt_at = ?2,
           last_error = ?3,
           next_attempt_at = ?4
         WHERE source_type = ?5 AND source_id = ?6",
        rusqlite::params![
            new_attempt,
            now,
            error,
            next_at,
            source_type.as_str(),
            source_id
        ],
    )?;
    Ok(())
}

#[cfg(test)]
#[path = "dirty_tracker_tests.rs"]
mod tests;