use std::fs;
use std::io;
use std::path::Path;

use obikpartitionner::{KmerPartition, OutputCol, PARTITIONS_SUBDIR};
use obisys::{Reporter, Stage, progress_bar};
use tracing::info;

use crate::error::{OKIError, OKIResult};
use crate::index::KmerIndex;
use crate::meta::{GenomeInfo, IndexMeta};
use crate::state::{IndexState, SENTINEL_INDEXED};

impl KmerIndex {
    /// Create a new index at `output` by projecting/aggregating the genome columns
    /// of `src` according to `specs`.
    ///
    /// `output_presence` — if true, output uses bit matrices (0/1), regardless of
    /// whether the source stores counts. The caller is responsible for ensuring all
    /// specs use logical operators when `output_presence=true` on a count source.
    pub fn select<P: AsRef<Path>>(
        output: P,
        src: &KmerIndex,
        specs: &[OutputCol],
        threshold: u32,
        output_presence: bool,
        force: bool,
        rep: &mut Reporter,
    ) -> OKIResult<Self> {
        let output = output.as_ref();

        if src.state() != IndexState::Indexed {
            return Err(OKIError::NotIndexed(src.root_path.clone()));
        }

        if output.exists() {
            if force {
                fs::remove_dir_all(output)?;
            } else {
                return Err(OKIError::Io(io::Error::new(
                    io::ErrorKind::AlreadyExists,
                    format!("{}: output directory already exists", output.display()),
                )));
            }
        }

        fs::create_dir_all(output)?;
        let mut meta = IndexMeta::new(src.meta.config.clone());
        meta.config.with_counts = !output_presence;
        meta.genomes = specs.iter()
            .map(|s| GenomeInfo::new(s.label.clone()))
            .collect();
        meta.write(output)?;

        let n_src_genomes  = src.meta.genomes.len();
        let n_partitions   = src.partition.n_partitions();

        fs::create_dir_all(output.join(PARTITIONS_SUBDIR))?;
        let dst_partition = KmerPartition::open_with_config(
            output,
            meta.config.kmer_size,
            meta.config.minimizer_size,
            meta.config.n_bits,
        )?;

        info!(
            "select: {} partition(s), {} source genome(s) → {} output column(s)",
            n_partitions, n_src_genomes, specs.len(),
        );

        let t   = Stage::start("select");
        let pb  = progress_bar("select", n_partitions as u64, "partitions");
        let src_partition = &src.partition;

        let order: Vec<usize> = (0..n_partitions).collect();
        let runner = crate::numa::PartitionRunner::new();
        runner.run(
            &order,
            |i| dst_partition.select_partition(src_partition, i, specs, n_src_genomes, threshold, output_presence, false),
            |_, _, _| { pb.inc(1); },
        ).map_err(OKIError::Partition)?;

        pb.finish_and_clear();
        rep.push(t.stop());

        fs::File::create(output.join(SENTINEL_INDEXED))?;

        let idx = KmerIndex::open(output)?;
        let t_pack = Stage::start("pack");
        idx.pack_matrices()?;
        rep.push(t_pack.stop());
        Ok(idx)
    }

    /// Rewrite the genome columns of this index in-place according to `specs`.
    ///
    /// The MPHF and unitig files are unchanged; only data matrices are rewritten.
    pub fn select_in_place(
        &mut self,
        specs: &[OutputCol],
        threshold: u32,
        output_presence: bool,
        rep: &mut Reporter,
    ) -> OKIResult<()> {
        if self.state() != IndexState::Indexed {
            return Err(OKIError::NotIndexed(self.root_path.clone()));
        }

        let n_src_genomes = self.meta.genomes.len();
        let n_partitions  = self.partition.n_partitions();

        let src_partition = KmerPartition::open_with_config(
            &self.root_path,
            self.meta.config.kmer_size,
            self.meta.config.minimizer_size,
            self.meta.config.n_bits,
        )?;

        info!(
            "select (in-place): {} partition(s), {} source genome(s) → {} output column(s)",
            n_partitions, n_src_genomes, specs.len(),
        );

        let t  = Stage::start("select");
        let pb = progress_bar("select", n_partitions as u64, "partitions");

        let partition = &self.partition;
        let order: Vec<usize> = (0..n_partitions).collect();
        let runner = crate::numa::PartitionRunner::new();
        runner.run(
            &order,
            |i| partition.select_partition(&src_partition, i, specs, n_src_genomes, threshold, output_presence, true),
            |_, _, _| { pb.inc(1); },
        ).map_err(OKIError::Partition)?;

        pb.finish_and_clear();
        rep.push(t.stop());

        self.meta.config.with_counts = !output_presence;
        self.meta.genomes = specs.iter()
            .map(|s| GenomeInfo::new(s.label.clone()))
            .collect();
        self.meta.write(&self.root_path)?;

        let t_pack = Stage::start("pack");
        self.pack_matrices()?;
        rep.push(t_pack.stop());
        Ok(())
    }
}