use std::fs;
use std::io;
use std::path::PathBuf;

use crate::pipeline::Stage;

pub mod pipeline;

const OUTPUT_GRAPH_DIR: &str = "graph";

pub type Result<T> = io::Result<T>;

#[derive(Debug, Clone)]
pub struct Config {
    pub output_dir: PathBuf,
    pub force: bool,
    pub target_stage: pipeline::Stage,
}

pub fn run(config: &Config) -> Result<()> {
    for stage in config.target_stage.with_prerequisites() {
        run_stage(config, stage)?;
    }

    Ok(())
}

fn get_output_dir(config: &Config, stage: Stage) -> Result<PathBuf> {
    let output_dir = config.output_dir.join(OUTPUT_GRAPH_DIR).join(stage.name());

    if output_dir.exists() && !output_dir.is_dir() {
        return Err(io::Error::new(
            io::ErrorKind::NotADirectory,
            format!("output path is not a directory: {path}", path = output_dir.display()),
        ));
    }

    if output_dir.is_dir() && fs::read_dir(&output_dir)?.next().transpose()?.is_some() {
        if !config.force {
            return Err(io::Error::new(
                io::ErrorKind::AlreadyExists,
                format!(
                    "output directory already exists and is not empty: {path}",
                    path = output_dir.display()
                ),
            ));
        }

        fs::remove_dir_all(&output_dir)?;
    }

    fs::create_dir_all(&output_dir)?;
    Ok(output_dir)
}

fn run_stage(config: &Config, stage: Stage) -> Result<()> {
    let output_dir = get_output_dir(config, stage)?;
    pipeline::run_stage(stage, &output_dir)
}