//! # CoRAL — Focal Amplification Reconstruction
//!
//! Wraps [CoRAL](https://github.com/AmpliconSuite/CoRAL) for ecDNA and focal
//! amplification cycle reconstruction from long-read WGS data.
//!
//! CoRAL takes as input:
//! - A tumour BAM (haplotagged recommended)
//! - A CN segments BED derived from SAVANA absolute CN output
//! - A seeds BED of amplified intervals (CN >= 4 * ploidy)
//!
//! ## Pipeline position
//!
//! CoRAL runs **after** SAVANA CNA fitting. The converter
//! [`savana_to_coral`] produces both required BED files from
//! `{sample}_segmented_absolute_copy_number.tsv` and
//! `{sample}_fitted_purity_ploidy.tsv`.
//!
//! ## Output files
//!
//! | File | Description |
//! |------|-------------|
//! | `coral_out/amplicon*_graph.txt` | Breakpoint graph per amplicon |
//! | `coral_out/amplicon*_cycles.txt` | Cycle decomposition per amplicon |
//!
//! ## Implemented traits
//!
//! - [`Initialize`] — Directory creation, SAVANA → CoRAL BED conversion
//! - [`ShouldRun`] — Skip if output directory already contains graph files
//! - [`JobCommand`] — CoRAL CLI command string
//! - [`LocalRunner`] — Local execution (conda env)
//! - [`SbatchRunner`] — SLURM submission
//! - [`Run`] — Unified execution via `run!` macro

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

use anyhow::Context;
use log::debug;
use tracing::info;

use crate::callers::savana::SavanaCN;
use crate::commands::{Command as JobCommand, LocalRunner, SbatchRunner, SlurmParams, SlurmRunner};
use crate::config::Config;
use crate::pipes::{Initialize, ShouldRun};
use crate::run;
use crate::runners::Run;

// ── CoRALSeed ─────────────────────────────────────────────────────────────────

/// CoRAL seed interval identification.
///
/// Runs `coral seed` to identify focally amplified genomic intervals
/// from SAVANA absolute CN segments. Produces a `*_CNV_SEEDS.bed` file
/// consumed by [`CoRALReconstruct`].
#[derive(Debug)]
pub struct CoRALSeed {
    pub id: String,
    pub config: Config,
    pub cn_segs_bed: String,
    pub output_dir: String,
    pub log_dir: String,
}

impl Initialize for CoRALSeed {
    fn initialize(id: &str, config: &Config) -> anyhow::Result<Self> {
        let id = id.to_string();
        let work_dir = format!("{}/{}/coral/work", config.result_dir, id);
        let output_dir = format!("{}/{}/coral/seed", config.result_dir, id);
        let log_dir = format!("{}/{}/log/coral", config.result_dir, id);
        let cn_segs_bed = format!("{work_dir}/cn_segs.bed");

        for dir in [&work_dir, &output_dir, &log_dir] {
            fs::create_dir_all(dir)
                .with_context(|| format!("Failed to create directory: {dir}"))?;
        }

        // Write SAVANA absolute CN → CoRAL cn_segs BED (no purity correction)
        let cn = SavanaCN::parse_file(&id, config)
            .with_context(|| format!("Failed to parse SAVANA CN segments for {id}"))?;
        cn.write_coral_cn_segs(Path::new(&cn_segs_bed))?;

        Ok(CoRALSeed {
            id,
            config: config.clone(),
            cn_segs_bed,
            output_dir,
            log_dir,
        })
    }
}

impl ShouldRun for CoRALSeed {
    /// Skip if the seeds BED already exists.
    fn should_run(&self) -> bool {
        !Path::new(&self.seeds_bed()).exists()
    }
}

impl CoRALSeed {
    /// Path of the seeds BED produced by `coral seed`.
    pub fn seeds_bed(&self) -> String {
        format!("{}/seeds_CNV_SEEDS.bed", self.output_dir)
    }
}

impl JobCommand for CoRALSeed {
    fn cmd(&self) -> String {
        format!(
            "source {conda_sh} && conda activate coral_env && \
                coral seed \
                --cn_segs         {cn_segs} \
                --gain            {gain} \
                --min-seed-size   {min_seed_size} \
                --max-seg-gap     {max_seg_gap} \
                --output-prefix   {}/seeds",
            self.output_dir,
            conda_sh      = self.config.conda_sh,
            cn_segs       = self.cn_segs_bed,
            gain          = self.config.coral_seed_gain,
            min_seed_size = self.config.coral_min_seed_size,
            max_seg_gap   = self.config.coral_max_seg_gap,
        )
    }
}

impl LocalRunner for CoRALSeed {}
impl SbatchRunner for CoRALSeed {
    fn slurm_params(&self) -> SlurmParams {
        SlurmParams {
            job_name: Some(format!("coral_seed_{}", self.id)),
            partition: Some(self.config.coral_slurm_partition.clone()),
            cpus_per_task: Some(1), // seed step is lightweight
            mem: Some("8G".into()),
            gres: None,
        }
    }
}

impl SlurmRunner for CoRALSeed {
    fn slurm_args(&self) -> Vec<String> {
        self.slurm_params().to_args()
    }
}

impl Run for CoRALSeed {
    fn run(&mut self) -> anyhow::Result<()> {
        if !self.should_run() {
            debug!("CoRAL seed already exists for {}; skipping.", self.id);
            return Ok(());
        }

        let report = run!(self.config, self)
            .with_context(|| format!("CoRAL seed failed for: {}", self.id))?;

        let log_file = format!("{}/coral_seed", self.log_dir);
        report
            .save_to_file(&log_file)
            .with_context(|| format!("Failed to write CoRAL seed log: {log_file}"))?;

        // Guard: bail if no seeds were produced (no focal amplifications)
        anyhow::ensure!(
            Path::new(&self.seeds_bed()).exists(),
            "CoRAL seed produced no output for {} — no focal amplifications detected \
             at gain={:.1}, min-seed-size={}",
            self.id,
            self.config.coral_seed_gain,
            self.config.coral_min_seed_size,
        );

        Ok(())
    }
}

// ── CoRALReconstruct ──────────────────────────────────────────────────────────

/// CoRAL focal amplification reconstruction.
///
/// Runs `coral reconstruct` from seed intervals produced by [`CoRALSeed`],
/// building a breakpoint graph and extracting ecDNA cycle candidates.
///
/// Output files per amplicon:
/// - `amplicon*_graph.txt`  — breakpoint graph
/// - `amplicon*_cycles.txt` — cycle decomposition
#[derive(Debug)]
pub struct CoRALReconstruct {
    pub id: String,
    pub config: Config,
    pub tumour_bam: String,
    pub cn_segs_bed: String,
    pub seeds_bed: String,
    pub output_dir: String,
    pub log_dir: String,
}

impl Initialize for CoRALReconstruct {
    fn initialize(id: &str, config: &Config) -> anyhow::Result<Self> {
        let seed = CoRALSeed::initialize(id, config)?;

        // seeds_bed must exist — CoRALSeed::run() must have completed first
        anyhow::ensure!(
            Path::new(&seed.seeds_bed()).exists(),
            "CoRAL seeds BED not found for {id}: {}. \
             Run CoRALSeed first.",
            seed.seeds_bed()
        );

        let output_dir = format!("{}/{}/coral/reconstruct", config.result_dir, id);
        fs::create_dir_all(&output_dir)
            .with_context(|| format!("Failed to create reconstruct dir: {output_dir}"))?;

        Ok(CoRALReconstruct {
            id: id.to_string(),
            config: config.clone(),
            tumour_bam: config.tumoral_bam(id),
            cn_segs_bed: seed.cn_segs_bed.clone(),
            seeds_bed: seed.seeds_bed(),
            output_dir,
            log_dir: seed.log_dir,
        })
    }
}

impl ShouldRun for CoRALReconstruct {
    /// Skip if at least one graph file already exists in the output directory.
    fn should_run(&self) -> bool {
        let out = Path::new(&self.output_dir);
        if !out.exists() {
            return true;
        }
        let has_graph = fs::read_dir(out)
            .map(|entries| {
                entries
                    .filter_map(|e| e.ok())
                    .any(|e| e.file_name().to_string_lossy().ends_with("_graph.txt"))
            })
            .unwrap_or(true);
        !has_graph
    }
}

impl JobCommand for CoRALReconstruct {
    fn cmd(&self) -> String {
        format!(
            "source {conda_sh} && conda activate coral_env && \
                coral reconstruct \
                --lr-bam          {bam} \
                --cnv-seed        {seeds} \
                --cn_segs         {cn_segs} \
                --ref_genome      {reference} \
                --output-prefix   {}/amplicon \
                --threads         {}",
            self.output_dir,
            self.config.coral_threads,
            conda_sh  = self.config.conda_sh,
            bam       = self.tumour_bam,
            seeds     = self.seeds_bed,
            cn_segs   = self.cn_segs_bed,
            reference = self.config.reference,
        )
    }
}

impl LocalRunner for CoRALReconstruct {}
impl SbatchRunner for CoRALReconstruct {
    fn slurm_params(&self) -> SlurmParams {
        SlurmParams {
            job_name: Some(format!("coral_reconstruct_{}", self.id)),
            partition: Some(self.config.coral_slurm_partition.clone()),
            cpus_per_task: Some(self.config.coral_threads.into()),
            mem: Some(self.config.coral_slurm_mem.clone()),
            gres: None,
        }
    }
}

impl SlurmRunner for CoRALReconstruct {
    fn slurm_args(&self) -> Vec<String> {
        self.slurm_params().to_args()
    }
}

impl Run for CoRALReconstruct {
    fn run(&mut self) -> anyhow::Result<()> {
        if !self.should_run() {
            debug!("CoRAL reconstruct already done for {}; skipping.", self.id);
            return Ok(());
        }

        let report = run!(self.config, self)
            .with_context(|| format!("CoRAL reconstruct failed for: {}", self.id))?;

        let log_file = format!("{}/coral_reconstruct", self.log_dir);
        report
            .save_to_file(&log_file)
            .with_context(|| format!("Failed to write CoRAL reconstruct log: {log_file}"))?;

        Ok(())
    }
}

// ── Top-level pipe ────────────────────────────────────────────────────────────

/// Runs the full CoRAL pipeline: seed identification → amplicon reconstruction.
///
/// Steps:
/// 1. [`CoRALSeed`]        — identify focally amplified seed intervals
/// 2. [`CoRALReconstruct`] — build breakpoint graph and extract ecDNA cycles
///
/// Returns `Ok(())` early (without error) if the seed step finds no amplified
/// intervals, since absence of focal amplifications is a valid biological result.
///
/// # Arguments
/// * `id`     - Sample identifier
/// * `config` - Pipeline configuration
pub fn run_coral(id: &str, config: &Config) -> anyhow::Result<()> {
    info!("CoRAL pipeline starting for {id}");

    // Step 1: seed
    let mut seed = CoRALSeed::initialize(id, config)
        .with_context(|| format!("CoRALSeed::initialize failed for {id}"))?;

    match seed.run() {
        Ok(()) => {}
        Err(e) if e.to_string().contains("no focal amplifications") => {
            info!("CoRAL: no focal amplifications for {id}; pipeline skipped.");
            return Ok(());
        }
        Err(e) => return Err(e),
    }

    // Step 2: reconstruct
    let mut reconstruct = CoRALReconstruct::initialize(id, config)
        .with_context(|| format!("CoRALReconstruct::initialize failed for {id}"))?;

    reconstruct
        .run()
        .with_context(|| format!("CoRALReconstruct::run failed for {id}"))?;

    info!("CoRAL pipeline complete for {id}");
    Ok(())
}