use std::path::Path;

use anyhow::Result;

use crate::package_installer::{AptConfig, PackageRequest};
use crate::{ImageSpec, Stage};

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct BuildPlan {
    spec: ImageSpec,
}

impl BuildPlan {
    pub fn compile(spec: ImageSpec) -> Result<Self> {
        spec.validate()?;
        Ok(Self { spec })
    }

    pub fn spec(&self) -> &ImageSpec {
        &self.spec
    }

    pub fn stages(&self) -> &'static [Stage] {
        &Stage::ORDERED
    }

    pub fn dependencies(&self, stage: Stage) -> &'static [Stage] {
        stage.dependencies()
    }

    /// Compile package-installation inputs from the validated immutable spec.
    /// This keeps ALT's external resolver behind the typed adapter boundary.
    pub fn package_request(
        &self,
        workdir: impl AsRef<Path>,
        apt_config: impl AsRef<Path>,
    ) -> Result<PackageRequest> {
        PackageRequest::new(
            workdir,
            AptConfig::new(apt_config)?,
            self.spec.packages.base.iter().cloned(),
            self.spec
                .packages
                .selectors
                .iter()
                .map(|selector| selector.as_str().to_owned()),
        )
    }
}