datafusion_iceberg 0.1.0

use anyhow::anyhow;
use datafusion::physical_plan::{ColumnStatistics, Statistics};
use iceberg_rust::catalog::relation::Relation;

use super::table::DataFusionTable;
use anyhow::Result;

impl DataFusionTable {
    pub(crate) async fn statistics(&self) -> Result<Statistics> {
        match &self.0 {
            Relation::Table(table) => table.manifests().iter().fold(
                Ok(Statistics {
                    num_rows: Some(0),
                    total_byte_size: None,
                    column_statistics: Some(vec![
                        ColumnStatistics {
                            null_count: None,
                            max_value: None,
                            min_value: None,
                            distinct_count: None
                        };
                        table.schema().fields.len()
                    ]),
                    is_exact: true,
                }),
                |acc, x| {
                    let acc = acc?;
                    Ok(Statistics {
                        num_rows: acc.num_rows.zip(x.added_files_count()).map(
                            |(num_rows, added_files_count)| num_rows + added_files_count as usize,
                        ),
                        total_byte_size: None,
                        column_statistics: Some(vec![
                            ColumnStatistics {
                                null_count: None,
                                max_value: None,
                                min_value: None,
                                distinct_count: None
                            };
                            table.schema().fields.len()
                        ]),
                        is_exact: true,
                    })
                },
            ),
            Relation::View(_) => Err(anyhow! {"Cannot get statistics for a view."}),
        }
    }
}