use vortex_error::VortexResult;

use crate::array::chunked::ChunkedArray;
use crate::array::ChunkedEncoding;
use crate::stats::{ArrayStatistics, Stat, StatisticsVTable, StatsSet};

impl StatisticsVTable<ChunkedArray> for ChunkedEncoding {
    fn compute_statistics(&self, array: &ChunkedArray, stat: Stat) -> VortexResult<StatsSet> {
        // for UncompressedSizeInBytes, we end up with sum of chunk uncompressed sizes
        // this ignores the `chunk_offsets` array child, so it won't exactly match self.nbytes()
        Ok(array
            .chunks()
            .map(|c| {
                let s = c.statistics();
                match stat {
                    Stat::IsConstant | Stat::IsSorted | Stat::IsStrictSorted => {
                        s.compute_all(&[stat, Stat::Min, Stat::Max]).ok()
                    }
                    _ => s.compute(stat).map(|s| StatsSet::of(stat, s)),
                }
                .unwrap_or_default()
            })
            .reduce(|acc, x| acc.merge_ordered(&x))
            .unwrap_or_default())
    }
}