//! # DeepSomatic Somatic Variant Calling Pipeline
//!
//! This module provides a pipeline runner for [DeepSomatic](https://github.com/google/deepsomatic),
//! a deep learning-based somatic variant caller for paired tumor-normal samples.
//!
//! ## Overview
//!
//! DeepSomatic performs somatic variant calling using:
//!
//! - CNN-based variant classification (derived from DeepVariant)
//! - Paired tumor-normal analysis
//! - Containerized execution via Singularity
//!
//! ## Key Features
//!
//! - **Deep learning-based** - CNN models specifically trained for somatic variant detection
//! - **Tumor-normal paired** - Leverages matched control for improved specificity
//! - **Platform flexibility** - Supports ONT, PacBio, and Illumina
//! - **Parallel execution** - Genome chunking for HPC scalability
//!
//! ## Requirements
//!
//! Before running DeepSomatic, ensure:
//! - Tumor and normal BAMs are indexed (`.bai` files present)
//! - Reference genome is accessible
//! - Singularity/Docker image is available
//! - Model type matches sequencing platform (`config.deepsomatic_model_type`)
//!
//! ## Execution Modes
//!
//! Execution mode is automatically selected via `config.slurm_runner`:
//!
//! - **Local** — Single-node execution
//! - **Slurm** — HPC job submission
//!
//! Both modes support chunked parallel execution via [`run_deepsomatic_chunked_with_merge`].
//!
//! ## Output Files
//!
//! PASS-filtered somatic variants:
//! ```text
//! {result_dir}/{id}/deepsomatic/{id}_{tumoral_name}_DeepSomatic.pass.vcf.gz
//! ```
//!
//! ## Usage
//!
//! ### Chunked Parallel Execution (Recommended for WGS)
//!
//! ```ignore
//! use pandora_lib_promethion::callers::deep_somatic::run_deepsomatic_chunked_with_merge;
//! use pandora_lib_promethion::config::Config;
//!
//! let config = Config::default();
//! // Run DeepSomatic in 30 parallel chunks
//! let outputs = run_deepsomatic_chunked_with_merge("sample_001", &config, 30)?;
//! # Ok::<(), anyhow::Error>(())
//! ```
//!
//! ### Single-Run Execution
//!
//! ```ignore
//! use pandora_lib_promethion::callers::deep_somatic::DeepSomatic;
//! use pandora_lib_promethion::config::Config;
//! use pandora_lib_promethion::pipes::Initialize;
//! use pandora_lib_promethion::runners::Run;
//!
//! let config = Config::default();
//! let mut caller = DeepSomatic::initialize("sample_001", &config)?;
//!
//! if caller.should_run() {
//!     caller.run()?;
//! }
//!
//! // Load somatic variants
//! let variants = caller.variants(&annotations)?;
//! println!("Found {} somatic variants", variants.variants.len());
//! # Ok::<(), anyhow::Error>(())
//! ```
//!
//! ## References
//!
//! - [DeepSomatic GitHub repository](https://github.com/google/deepsomatic)

use std::{
    fmt, fs,
    path::{Path, PathBuf},
    process::{Command as ProcessCommand, Stdio},
};

use anyhow::Context;
use log::{debug, info};
use rayon::prelude::*;
use regex::Regex;
use rust_htslib::bam::{self, Read};
use uuid::Uuid;

use crate::{
    annotation::{Annotation, Annotations, Caller, CallerCat, Sample},
    collection::vcf::Vcf,
    commands::{
        bcftools::{BcftoolsConcat, BcftoolsIndex, BcftoolsKeepPass},
        Command as JobCommand, LocalBatchRunner, LocalRunner, SbatchRunner, SlurmParams,
        SlurmRunner,
    },
    config::Config,
    helpers::{
        get_genome_sizes_in_header_order, is_file_older, remove_dir_if_exists,
        singularity_bind_flags, split_ordered_genome_into_n_regions_exact,
    },
    io::vcf::read_vcf,
    locker::SampleLock,
    pipes::{Initialize, ShouldRun, Version},
    run, run_many,
    runners::Run,
    variant::{
        variant_collection::VariantCollection,
        vcf_variant::{Label, Variants},
    },
};

/// DeepSomatic paired tumor-normal somatic variant caller.
///
/// Executes DeepSomatic for somatic SNV and indel detection using matched
/// tumor and normal BAM files with automatic post-processing (PASS filtering).
///
/// # Fields
///
/// - `id` - Sample identifier (e.g., "34528")
/// - `regions` - Space-separated list of genomic regions to process (e.g., "chr1 chr2 chr3")
/// - `log_dir` - Directory for execution logs (e.g., "{result_dir}/{id}/log/deepsomatic")
/// - `config` - Global pipeline configuration
/// - `part_index` - Optional chunk index for parallel execution (e.g., `Some(3)` for part 3 of N)
///
/// # Execution Modes
///
/// - **Local** - Direct execution
/// - **Slurm** - Single job submission
/// - **Chunked** - Parallel genome-wide execution via [`run_deepsomatic_chunked_with_merge`]
#[derive(Debug, Clone)]
pub struct DeepSomatic {
    /// Sample identifier
    pub id: String,
    /// Space-separated list of genomic regions to process
    pub regions: String,
    /// Directory for log file storage
    pub log_dir: String,
    /// Global pipeline configuration
    pub config: Config,
    /// Optional part index for chunked parallel runs (1-indexed)
    pub part_index: Option<usize>,
}

impl fmt::Display for DeepSomatic {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        writeln!(f, "🧬 DeepSomatic")?;
        writeln!(f, "   Case ID  : {}", self.id)?;
        writeln!(f, "   Regions  : {}", self.regions)?;
        writeln!(f, "   Log dir  : {}", self.log_dir)?;
        writeln!(
            f,
            "   Part     : {}",
            self.part_index
                .map_or("full".into(), |n| format!("part{n}"))
        )
    }
}

impl Initialize for DeepSomatic {
    fn initialize(id: &str, config: &Config) -> anyhow::Result<Self> {
        let id = id.to_string();
        info!("Initializing DeepSomatic for {id}.");

        let log_dir = format!("{}/{}/log/deepsomatic", config.result_dir, &id);

        let regions = (1..=22)
            .map(|i| format!("chr{i}"))
            .chain(["chrX", "chrY", "chrM"].into_iter().map(String::from))
            .collect::<Vec<String>>();

        let deep_somatic = Self {
            id,
            regions: regions.join(" "),
            log_dir,
            config: config.clone(),
            part_index: None,
        };

        if deep_somatic.config.deepsomatic_force {
            remove_dir_if_exists(&deep_somatic.config.deepsomatic_output_dir(&deep_somatic.id))?;
        }

        Ok(deep_somatic)
    }
}

impl ShouldRun for DeepSomatic {
    fn should_run(&self) -> bool {
        let passed_vcf = &self.config.deepsomatic_passed_vcf(&self.id);
        let normal_older =
            is_file_older(passed_vcf, &self.config.normal_bam(&self.id), true).unwrap_or(true);
        let tumor_older =
            is_file_older(passed_vcf, &self.config.tumoral_bam(&self.id), true).unwrap_or(true);

        let result = normal_older || tumor_older;
        if result {
            info!("DeepSomatic should run for id: {}.", self.id);
        }
        result
    }
}

impl JobCommand for DeepSomatic {
    fn init(&mut self) -> anyhow::Result<()> {
        let output_dir = self.part_output_dir();
        fs::create_dir_all(&output_dir)
            .with_context(|| format!("Failed to create dir: {output_dir}"))?;
        fs::create_dir_all(&self.log_dir)
            .with_context(|| format!("Failed to create dir: {}", self.log_dir))?;
        Ok(())
    }

    fn cmd(&self) -> String {
        let output_dir = self.part_output_dir();
        let output_vcf_path = self.output_vcf_path();
        let sample_name_tumor = format!("{}_{}", self.id, self.config.tumoral_name);
        let sample_name_normal = format!("{}_{}", self.id, self.config.normal_name);

        let log_subdir = match self.part_index {
            Some(idx) => format!("{}_DeepSomatic_part{idx}_logs", sample_name_tumor),
            None => format!("{}_DeepSomatic_logs", sample_name_tumor),
        };

        let bind_flags = singularity_bind_flags([
            &self.config.normal_bam(&self.id),
            &self.config.tumoral_bam(&self.id),
            &self.config.reference,
            &output_dir,
            &self.log_dir,
            &self.config.tmp_dir,
        ]);

        let output_vcf = format!(
            "/output/{}",
            Path::new(&output_vcf_path)
                .file_name()
                .unwrap()
                .to_string_lossy()
        );

        format!(
            "{singularity_bin} exec --cleanenv \
            {binds} \
            --bind {output_dir}:/output \
            {image} \
            /opt/deepvariant/bin/deepsomatic/run_deepsomatic \
            --model_type={model_type} \
            --ref={reference} \
            --reads_normal={normal_bam} \
            --reads_tumor={tumor_bam} \
            --regions=\"{regions}\" \
            --output_vcf={output_vcf} \
            --num_shards={threads} \
            --logging_dir=/output/{log_subdir} \
            --vcf_stats_report=true \
            --dry_run=false \
            --sample_name_tumor={sample_name_tumor} \
            --sample_name_normal={sample_name_normal}",
            singularity_bin = self.config.singularity_bin,
            binds = bind_flags,
            output_dir = output_dir,
            image = self.config.deepsomatic_image,
            model_type = self.config.deepsomatic_model_type,
            reference = self.config.reference,
            normal_bam = self.config.normal_bam(&self.id),
            tumor_bam = self.config.tumoral_bam(&self.id),
            regions = self.regions,
            threads = self.config.deepsomatic_threads,
        )
    }
}

impl LocalRunner for DeepSomatic {}
impl LocalBatchRunner for DeepSomatic {}

impl SlurmRunner for DeepSomatic {
    fn slurm_args(&self) -> Vec<String> {
        let batch_id = self.part_index.map(|i| format!("_{i}")).unwrap_or_default();
        SlurmParams {
            job_name: Some(format!("deepsomatic_{}{}", self.id, batch_id)),
            cpus_per_task: Some(self.config.deepsomatic_threads as u32),
            mem: Some("60G".into()),
            partition: Some("shortq".into()),
            gres: None,
        }
        .to_args()
    }
}

impl SbatchRunner for DeepSomatic {
    fn slurm_params(&self) -> SlurmParams {
        let batch_id = self.part_index.map(|i| format!("_{i}")).unwrap_or_default();
        SlurmParams {
            job_name: Some(format!("deepsomatic_{}{}", self.id, batch_id)),
            cpus_per_task: Some(self.config.deepsomatic_threads as u32),
            mem: Some("60G".into()),
            partition: Some("shortq".into()),
            gres: None,
        }
    }
}

impl DeepSomatic {
    fn part_output_dir(&self) -> String {
        let base_dir = self.config.deepsomatic_output_dir(&self.id);
        match self.part_index {
            Some(idx) => format!("{base_dir}/part{idx}"),
            None => base_dir,
        }
    }

    fn output_vcf_path(&self) -> String {
        let output_dir = self.part_output_dir();
        format!(
            "{output_dir}/{}_{}_DeepSomatic.vcf.gz",
            self.id, self.config.tumoral_name
        )
    }

    fn passed_vcf_path(&self) -> String {
        match self.part_index {
            Some(_) => self.output_vcf_path().replace(".vcf.gz", ".pass.vcf.gz"),
            None => self.config.deepsomatic_passed_vcf(&self.id),
        }
    }

    fn filter_pass(&self) -> anyhow::Result<()> {
        let output_vcf = self.output_vcf_path();
        let vcf_passed = self.passed_vcf_path();

        if Path::new(&vcf_passed).exists() {
            debug!("PASS VCF already exists: {vcf_passed}");
            return Ok(());
        }

        info!(
            "Filtering DeepSomatic PASS variants for {} (part: {:?})",
            self.id, self.part_index
        );

        let mut cmd = BcftoolsKeepPass::from_config(&self.config, output_vcf, &vcf_passed);
        let report = run!(&self.config, &mut cmd)
            .with_context(|| format!("Failed to filter PASS for {}", self.id))?;
        report
            .save_to_file(format!("{}/bcftools_pass_", self.log_dir))
            .context("Can't save bcftools PASS logs")?;

        let mut cmd = BcftoolsIndex::from_config(&self.config, vcf_passed);
        let report = run!(&self.config, &mut cmd)
            .with_context(|| format!("Failed to index vcf PASS for {}", self.id))?;
        report
            .save_to_file(format!("{}/bcftools_index_", self.log_dir))
            .context("Failed to save bcftools index logs")?;

        Ok(())
    }
}

impl Run for DeepSomatic {
    fn run(&mut self) -> anyhow::Result<()> {
        let lock_dir = format!("{}/locks", self.config.result_dir);
        let _lock = SampleLock::acquire(&lock_dir, &self.id, "deepsomatic")
            .with_context(|| format!("Cannot start DeepSomatic chunked for {}", self.id))?;

        if !self.should_run() {
            info!("DeepSomatic is up-to-data.");
            return Ok(());
        }

        if self.config.slurm_runner {
            run_deepsomatic_chunked(&self.id, &self.config, 30)
        } else {
            run!(&self.config, self)?;
            self.filter_pass()
        }
    }
}

impl CallerCat for DeepSomatic {
    fn caller_cat(&self) -> Annotation {
        Annotation::Callers(Caller::DeepSomatic, Sample::Somatic)
    }
}

impl Variants for DeepSomatic {
    fn variants(&self, annotations: &Annotations) -> anyhow::Result<VariantCollection> {
        let caller = self.caller_cat();
        let vcf_passed = self.config.deepsomatic_passed_vcf(&self.id);

        info!("Loading variants from {caller}: {vcf_passed}");

        let variants = read_vcf(&vcf_passed)
            .with_context(|| format!("Failed to read DeepSomatic VCF {vcf_passed}"))?;

        variants.par_iter().for_each(|v| {
            annotations.insert_update(v.hash(), std::slice::from_ref(&caller));
        });

        info!("{caller}: {} variants loaded", variants.len());

        Ok(VariantCollection {
            variants,
            vcf: Vcf::new(vcf_passed.into())?,
            caller,
        })
    }
}

impl Label for DeepSomatic {
    fn label(&self) -> String {
        self.caller_cat().to_string()
    }
}

impl Version for DeepSomatic {
    fn version(config: &Config) -> anyhow::Result<String> {
        let out = ProcessCommand::new("bash")
            .arg("-c")
            .arg(format!(
                "{} exec {} /opt/deepvariant/bin/deepsomatic/run_deepsomatic --version",
                config.singularity_bin, config.deepsomatic_image
            ))
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .output()
            .context("Failed to spawn Singularity process")?;

        if !out.status.success() {
            let combined = format!(
                "{}{}",
                String::from_utf8_lossy(&out.stdout),
                String::from_utf8_lossy(&out.stderr)
            );
            anyhow::bail!(
                "Singularity exec failed with status {}: {}",
                out.status,
                combined
            );
        }

        let combined = format!(
            "{}{}",
            String::from_utf8_lossy(&out.stdout),
            String::from_utf8_lossy(&out.stderr)
        );

        parse_deepsomatic_version(&combined)
    }

    fn version_slurm(config: &Config) -> anyhow::Result<String> {
        struct DeepSomaticVersionJob<'a> {
            config: &'a Config,
        }

        impl JobCommand for DeepSomaticVersionJob<'_> {
            fn cmd(&self) -> String {
                format!(
                    "{} exec {} /opt/deepvariant/bin/deepsomatic/run_deepsomatic --version",
                    self.config.singularity_bin, self.config.deepsomatic_image
                )
            }
        }

        impl SlurmRunner for DeepSomaticVersionJob<'_> {
            fn slurm_args(&self) -> Vec<String> {
                SlurmParams {
                    job_name: Some("deepsomatic_version".into()),
                    partition: Some("shortq".into()),
                    cpus_per_task: Some(1),
                    mem: Some("10G".into()),
                    gres: None,
                }
                .to_args()
            }
        }

        let mut job = DeepSomaticVersionJob { config };
        let out = crate::commands::SlurmRunner::exec(&mut job)
            .context("Failed to run DeepSomatic --version via Slurm")?;

        let mut combined = out.stdout.clone();
        if let Some(epilog) = &out.slurm_epilog {
            combined.push_str(&epilog.to_string());
        }
        combined.push_str(&out.stderr);

        parse_deepsomatic_version(&combined)
    }
}

fn parse_deepsomatic_version(output: &str) -> anyhow::Result<String> {
    let deepsomatic_re = Regex::new(r"(?mi)\bdeepsomatic(?:\s+version)?\s*[:=]?\s*([^\s]+)")
        .expect("DeepSomatic version regex is valid");
    if let Some(caps) = deepsomatic_re.captures(output) {
        return Ok(caps
            .get(1)
            .expect("Regex has capture group 1")
            .as_str()
            .to_string());
    }

    // Fallback for containers that only expose the embedded DeepVariant version.
    let deepvariant_re =
        Regex::new(r"(?m)DeepVariant version\s+([^\s]+)").expect("DeepVariant regex is valid");
    let caps = deepvariant_re
        .captures(output)
        .context("Could not parse DeepSomatic version from output")?;
    Ok(caps
        .get(1)
        .expect("Regex has capture group 1")
        .as_str()
        .to_string())
}

fn merge_deepsomatic_parts(base: &DeepSomatic, n_parts: usize) -> anyhow::Result<()> {
    let mut part_pass_paths: Vec<PathBuf> = Vec::with_capacity(n_parts);

    for i in 1..=n_parts {
        let mut ds = base.clone();
        ds.part_index = Some(i);
        let part_pass = ds.passed_vcf_path();

        anyhow::ensure!(
            Path::new(&part_pass).exists(),
            "Missing DeepSomatic part {i} PASS VCF: {part_pass}"
        );

        part_pass_paths.push(PathBuf::from(part_pass));
    }

    let final_passed_vcf = base.config.deepsomatic_passed_vcf(&base.id);
    let rand = Uuid::new_v4();
    let final_tmp = format!("{final_passed_vcf}_{rand}.tmp");
    let final_tmp_csi = format!("{final_passed_vcf}_{rand}.tmp.csi");

    if let Some(parent) = Path::new(&final_passed_vcf).parent() {
        fs::create_dir_all(parent)?;
    }

    info!(
        "Concatenating {} DeepSomatic part VCFs into {}",
        n_parts, final_passed_vcf
    );

    let mut concat = BcftoolsConcat::from_config(&base.config, part_pass_paths, &final_tmp);
    run!(&base.config, &mut concat)
        .context("Failed to run bcftools concat for DeepSomatic parts")?;

    fs::rename(&final_tmp, &final_passed_vcf)
        .context("Failed to rename merged DeepSomatic PASS VCF")?;

    fs::rename(&final_tmp_csi, format!("{final_passed_vcf}.csi"))
        .context("Failed to rename merged DeepVariant PASS VCF CSI")?;

    info!(
        "Successfully merged {} DeepSomatic parts into {}",
        n_parts, final_passed_vcf
    );

    Ok(())
}

/// Runs DeepSomatic in parallel chunks, then merges results.
///
/// Splits the genome into N equal-sized regions, runs DeepSomatic on each region
/// in parallel (local or Slurm based on `config.slurm_runner`), filters PASS variants,
/// and concatenates the final VCF.
///
/// # Arguments
///
/// * `id` - Sample identifier
/// * `config` - Global pipeline configuration
/// * `n_parts` - Number of parallel chunks (typically 20-30 for whole-genome)
///
/// # Returns
///
/// `Ok(())` on success, or an error if any step fails.
///
/// # Errors
///
/// Returns an error if:
/// - `n_parts` is 0
/// - Tumor or normal BAM file cannot be opened
/// - BAM header is malformed
/// - DeepSomatic execution fails on any part
/// - PASS filtering fails
/// - VCF merging fails
/// - Output directory cannot be created
///
/// # Example
///
/// ```ignore
/// let config = Config::default();
/// run_deepsomatic_chunked("sample_001", &config, 30)?;
/// ```
pub fn run_deepsomatic_chunked(id: &str, config: &Config, n_parts: usize) -> anyhow::Result<()> {
    anyhow::ensure!(n_parts > 0, "n_parts must be > 0");

    // Lock at the chunked level (caller may have already locked, but this is idempotent protection)
    // let lock_dir = format!("{}/locks", config.result_dir);
    // let _lock = SampleLock::acquire(&lock_dir, id, "deepsomatic")
    //     .with_context(|| format!("Cannot start DeepSomatic chunked for {}", id))?;

    let base = DeepSomatic::initialize(id, config)?;

    // if !base.should_run() {
    //     debug!("DeepSomatic PASS VCF already up-to-date for {id}, skipping.");
    //     return Ok(());
    // }

    // Get genome sizes from tumor BAM header
    let tumor_bam = config.tumoral_bam(id);
    let reader = bam::Reader::from_path(&tumor_bam)
        .with_context(|| format!("Failed to open BAM: {tumor_bam}"))?;
    let genome_sizes = get_genome_sizes_in_header_order(reader.header())?;

    let region_chunks = split_ordered_genome_into_n_regions_exact(&genome_sizes, n_parts)
        .into_iter()
        .map(|v| v.join(" "))
        .collect::<Vec<String>>();

    let actual_n_parts = region_chunks.len();

    info!(
        "Running DeepSomatic in {} parallel parts for {}",
        actual_n_parts, id
    );

    let mut jobs = Vec::with_capacity(actual_n_parts);
    for (i, regions) in region_chunks.into_iter().enumerate() {
        let mut job = base.clone();
        job.regions = regions;
        job.part_index = Some(i + 1);
        job.log_dir = format!("{}/part{}", base.log_dir, i + 1);
        info!("Planned DeepSomatic job:\n{job}");
        jobs.push(job);
    }

    // Run DeepSomatic jobs
    let outputs = run_many!(config, jobs.clone())?;
    for output in outputs.iter() {
        output.save_to_file(format!("{}/deepsomatic_", base.log_dir))?;
    }

    // Filter PASS variants for each part in parallel
    info!(
        "Filtering PASS variants for all {} parts in parallel",
        actual_n_parts
    );
    let filter_jobs: Vec<_> = jobs
        .iter()
        .map(|job| {
            BcftoolsKeepPass::from_config(&job.config, job.output_vcf_path(), job.passed_vcf_path())
        })
        .collect();
    run_many!(config, filter_jobs)?;

    // Merge PASS VCFs
    merge_deepsomatic_parts(&base, actual_n_parts)?;

    info!(
        "DeepSomatic completed for {}: {} parts merged",
        id, actual_n_parts
    );

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::helpers::test_init;

    #[test]
    fn deepsomatic_version() -> anyhow::Result<()> {
        test_init();
        let vl = DeepSomatic::version(&Config::default())?;
        info!("DeepSomatic local version: {vl}");
        let vs = DeepSomatic::version_slurm(&Config::default())?;
        info!("DeepSomatic slurm version: {vs}");
        assert_eq!(vl, vs);
        Ok(())
    }

    #[test]
    fn deepsomatic_run() -> anyhow::Result<()> {
        test_init();
        let config = Config::default();
        run_deepsomatic_chunked("DUMCO", &config, 50)
    }
}