// Copyright (c) 2023-2026 ParadeDB, Inc.
//
// This file is part of ParadeDB - Postgres for Search and Analytics
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.

// Tests for ParadeDB's Aggregate Custom Scan implementation

use pretty_assertions::assert_eq;
use rstest::*;
use serde_json::Value;
use sqlx::PgConnection;
use tests::fixtures::*;

fn assert_uses_custom_scan(conn: &mut PgConnection, enabled: bool, query: impl AsRef<str>) {
    let (plan,) = format!(" EXPLAIN (FORMAT JSON) {}", query.as_ref()).fetch_one::<(Value,)>(conn);
    eprintln!("{plan:#?}");
    assert_eq!(
        enabled,
        plan.to_string().contains("ParadeDB Aggregate Scan")
    );
}

#[rstest]
fn test_count(mut conn: PgConnection) {
    SimpleProductsTable::setup().execute(&mut conn);

    // Use the aggregate custom scan only if it is enabled.
    for enabled in [true, false] {
        format!("SET paradedb.enable_aggregate_custom_scan TO {enabled};").execute(&mut conn);

        let query = "SELECT COUNT(*) FROM paradedb.bm25_search WHERE description @@@ 'keyboard'";

        assert_uses_custom_scan(&mut conn, enabled, query);

        let (count,) = query.fetch_one::<(i64,)>(&mut conn);
        assert_eq!(count, 2, "With custom scan: {enabled}");
    }
}

#[rstest]
fn test_count_with_group_by(mut conn: PgConnection) {
    SimpleProductsTable::setup().execute(&mut conn);

    "SET paradedb.enable_aggregate_custom_scan TO on;".execute(&mut conn);
    "SET client_min_messages TO warning;".execute(&mut conn);

    // First test simple COUNT(*) without GROUP BY
    let simple_count = "SELECT COUNT(*) FROM paradedb.bm25_search";
    eprintln!("Testing simple COUNT(*)");
    let (plan,) = format!("EXPLAIN (FORMAT JSON) {simple_count}").fetch_one::<(Value,)>(&mut conn);
    eprintln!("Simple COUNT(*) plan: {plan:#?}");
    eprintln!(
        "Uses aggregate scan: {}",
        plan.to_string().contains("ParadeDB Aggregate Scan")
    );

    // Test COUNT(*) with WHERE clause (like the working test)
    let count_with_where =
        "SELECT COUNT(*) FROM paradedb.bm25_search WHERE description @@@ 'keyboard'";
    eprintln!("\nTesting COUNT(*) with WHERE clause");
    let (plan,) =
        format!("EXPLAIN (FORMAT JSON) {count_with_where}").fetch_one::<(Value,)>(&mut conn);
    eprintln!(
        "COUNT(*) with WHERE plan uses aggregate scan: {}",
        plan.to_string().contains("ParadeDB Aggregate Scan")
    );

    // Then test WITHOUT WHERE clause but WITH GROUP BY
    let query_no_where = r#"
        SELECT rating, COUNT(*) 
        FROM paradedb.bm25_search 
        GROUP BY rating 
        ORDER BY rating
    "#;

    eprintln!("Testing query without WHERE clause");
    let (plan,) =
        format!("EXPLAIN (FORMAT JSON) {query_no_where}").fetch_one::<(Value,)>(&mut conn);
    eprintln!("Plan without WHERE: {plan:#?}");
    eprintln!(
        "Uses aggregate scan: {}",
        plan.to_string().contains("ParadeDB Aggregate Scan")
    );

    // Then test WITH WHERE clause
    let query = r#"
        SELECT rating, COUNT(*) 
        FROM paradedb.bm25_search 
        WHERE description @@@ 'shoes' 
        GROUP BY rating 
        ORDER BY rating
    "#;

    // Verify it uses the aggregate custom scan
    assert_uses_custom_scan(&mut conn, true, query);

    // Execute and verify results
    let results: Vec<(i32, i64)> = query.fetch(&mut conn);
    assert_eq!(results.len(), 3); // We should have 3 distinct ratings for shoes
    assert_eq!(results[0], (3, 1)); // rating 3, count 1
    assert_eq!(results[1], (4, 1)); // rating 4, count 1
    assert_eq!(results[2], (5, 1)); // rating 5, count 1
}

#[rstest]
fn test_group_by(mut conn: PgConnection) {
    SimpleProductsTable::setup().execute(&mut conn);

    "SET paradedb.enable_aggregate_custom_scan TO on;".execute(&mut conn);

    // Supports GROUP BY with aggregate scan
    assert_uses_custom_scan(
        &mut conn,
        true,
        r#"
        SELECT rating, COUNT(*)
        FROM paradedb.bm25_search WHERE
        description @@@ 'keyboard'
        GROUP BY rating
        ORDER BY rating
        "#,
    );
}

#[rstest]
fn test_group_by_null_bucket(mut conn: PgConnection) {
    SimpleProductsTable::setup().execute(&mut conn);

    "SET paradedb.enable_aggregate_custom_scan TO on;".execute(&mut conn);

    assert_uses_custom_scan(
        &mut conn,
        true,
        r#"
        SELECT rating, COUNT(*)
        FROM paradedb.bm25_search
        WHERE description @@@ 'keyboard'
        GROUP BY rating
        ORDER BY rating NULLS FIRST
    "#,
    );
}

#[rstest]
fn test_no_bm25_index(mut conn: PgConnection) {
    "CALL paradedb.create_bm25_test_table(table_name => 'no_bm25', schema_name => 'paradedb');"
        .execute(&mut conn);

    "SET paradedb.enable_aggregate_custom_scan TO on;".execute(&mut conn);

    // Do not use the aggregate custom scan on non-bm25 indexed tables.
    assert_uses_custom_scan(&mut conn, false, "SELECT COUNT(*) FROM paradedb.no_bm25");
}

#[rstest]
fn test_other_aggregates(mut conn: PgConnection) {
    SimpleProductsTable::setup().execute(&mut conn);

    "SET paradedb.enable_aggregate_custom_scan TO on;".execute(&mut conn);

    for aggregate_func in ["SUM(rating)", "AVG(rating)", "MIN(rating)", "MAX(rating)"] {
        assert_uses_custom_scan(
            &mut conn,
            true,
            format!(
                r#"
                SELECT {aggregate_func}
                FROM paradedb.bm25_search WHERE
                description @@@ 'keyboard'
                "#
            ),
        );
    }
}
