//! Orchestrates one run of check -> fetch -> verify -> build ->
//! sanity-check -> publish across every configured package, plus the
//! `review` subcommand for tier 4-6 approvals. The only module that calls
//! more than one other pipeline-stage module — see docs/ARCHITECTURE.md > "main
//! is a dispatcher, not the program" for why this lives here and not in
//! `main.rs`.

use crate::builder;
use crate::checker;
use crate::config::{self, Package};
use crate::fetcher::{self, DownloadedAsset};
use crate::notifier::{self, Event};
use crate::paths::Paths;
use crate::publisher;
use crate::sanity;
use crate::source::Endpoints;
use crate::state;
use crate::verifier::{self, VerificationResult};
use anyhow::{Context, Result, bail};
use std::path::{Path, PathBuf};

/// Not a repo pkgwatch invents: this is the existing, already-registered
/// local pacman repo on this box (see `[custom]` in /etc/pacman.conf and
/// its `Server = file://...` line). pkgwatch adds packages to it; it does
/// not create the repo or touch pacman.conf.
const CUSTOM_REPO_NAME: &str = "custom";
const CUSTOM_REPO_SUBPATH: &str = ".local/share/pacman/custom";

fn build_client() -> Result<reqwest::blocking::Client> {
    Ok(reqwest::blocking::Client::builder()
        .user_agent("pkgwatch/0.1 (PoC; https://code.austinschaefer.com)")
        .build()?)
}

fn custom_repo_dir() -> Result<PathBuf> {
    // Override for testing against a scratch repo instead of the real one
    // at $HOME/.local/share/pacman/custom.
    if let Ok(dir) = std::env::var("PKGWATCH_REPO_DIR") {
        return Ok(PathBuf::from(dir));
    }
    let home = std::env::var("HOME").context("HOME is not set")?;
    Ok(Path::new(&home).join(CUSTOM_REPO_SUBPATH))
}

/// Adds a hint to the bare "No such file" a missing config dir would give:
/// the dir is no longer relative to the cwd, so a checkout's `packages.d/`
/// isn't picked up on its own (see docs/SPEC.md > Paths).
fn load_packages(packages_dir: &Path) -> Result<Vec<(String, Package)>> {
    config::load_packages_dir(packages_dir).with_context(|| {
        format!(
            "no package config at {} (set PKGWATCH_CONFIG_DIR to the directory containing \
             packages.d, or see docs/SPEC.md > Paths for moving a checkout's packages.d/ there)",
            packages_dir.display()
        )
    })
}

pub fn run_check() -> Result<()> {
    let client = build_client()?;
    let Paths {
        packages_dir,
        state_dir,
        work_dir,
    } = Paths::from_env()?;

    let packages = load_packages(&packages_dir)?;
    if packages.is_empty() {
        println!("no packages configured under {}/", packages_dir.display());
        return Ok(());
    }

    let mut any_failed = false;
    for (name, pkg) in &packages {
        println!("== {name} ({}) ==", pkg.repo);
        let result = Endpoints::for_package(pkg).and_then(|endpoints| {
            process_package(&client, &endpoints, &state_dir, &work_dir, name, pkg)
        });
        if let Err(err) = result {
            eprintln!("  error: {err:#}");
            any_failed = true;
        }
    }

    if any_failed {
        bail!("one or more packages failed — see errors above");
    }
    Ok(())
}

/// What to do about a package after verification, derived purely from the
/// verification outcome and whether this exact version is already queued
/// for review — no I/O. See docs/ARCHITECTURE.md > "separate pure decision
/// logic from I/O."
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum TierAction {
    /// Verification failed outright — don't build, don't touch state.
    VerificationFailed,
    /// Tier 1-3: safe to auto-build and publish immediately.
    Publish,
    /// Tier 4-6, and this exact version was already flagged on an earlier
    /// run — nothing new to report.
    StillPending,
    /// Tier 4-6, and this version hasn't been flagged yet.
    NewlyPending,
}

fn decide_tier_action(tier: u8, passed: bool, already_pending_this_version: bool) -> TierAction {
    if !passed {
        return TierAction::VerificationFailed;
    }
    if tier <= 3 {
        return TierAction::Publish;
    }
    if already_pending_this_version {
        TierAction::StillPending
    } else {
        TierAction::NewlyPending
    }
}

fn process_package(
    client: &reqwest::blocking::Client,
    endpoints: &Endpoints,
    state_dir: &Path,
    work_dir: &Path,
    name: &str,
    pkg: &Package,
) -> Result<()> {
    let latest = checker::latest_release(client, endpoints, &pkg.repo)?;
    let last_seen = state::load_last_version(state_dir, name);
    if last_seen.as_deref() == Some(latest.as_str()) {
        println!("  up to date at {latest}");
        return Ok(());
    }
    println!("  new version detected: {latest} (previously: {last_seen:?})");

    let fetched = fetch_and_verify(client, endpoints, work_dir, name, pkg, &latest)?;
    println!("  fetched {}", fetched.asset.path.display());
    println!(
        "  verification (tier {}): {} — {}",
        fetched.verification.tier,
        if fetched.verification.passed {
            "PASS"
        } else {
            "FAIL"
        },
        fetched.verification.justification
    );

    let previously_pending = state::load_pending_version(state_dir, name);
    let already_pending = previously_pending.as_deref() == Some(latest.as_str());
    match decide_tier_action(
        fetched.verification.tier,
        fetched.verification.passed,
        already_pending,
    ) {
        // Bail rather than just print-and-return: a verification failure
        // is exactly the kind of event a monitoring setup (systemd
        // OnFailure=, cron mail-on-error) needs a non-zero exit to catch —
        // see run_check, which treats an Err here as a failed package.
        TierAction::VerificationFailed => {
            bail!("verification failed — not publishing, not updating state");
        }
        TierAction::Publish => {
            println!("  tier 1-3 pass: building + publishing");
            build_and_publish(name, pkg, &latest, &fetched)?;
            state::save_last_version(state_dir, name, &latest)?;
            state::clear_pending_version(state_dir, name)?;
            println!("  published {name} {latest}");
            notifier::notify(Event::Published {
                name,
                version: &latest,
            });
        }
        TierAction::StillPending => {
            println!("  tier 4-6 pass: still pending review (`pkgwatch review` to see it)");
        }
        TierAction::NewlyPending => {
            state::save_pending_version(state_dir, name, &latest)?;
            match previously_pending {
                Some(superseded) => println!(
                    "  tier 4-6 pass: flagged for human review, superseding still-unreviewed {superseded} (`pkgwatch review` to approve {latest})"
                ),
                None => println!(
                    "  tier 4-6 pass: flagged for human review (`pkgwatch review` to approve)"
                ),
            }
            notifier::notify(Event::NeedsReview {
                name,
                version: &latest,
            });
        }
    }
    Ok(())
}

struct FetchVerifyResult {
    version: String,
    asset_name: String,
    dest_dir: PathBuf,
    asset: DownloadedAsset,
    verification: VerificationResult,
}

/// Shared by the normal check loop (tier 1-3 auto-path) and `pkgwatch
/// review --approve` (which re-verifies before publishing rather than
/// trusting a possibly-stale flag from an earlier run).
fn fetch_and_verify(
    client: &reqwest::blocking::Client,
    endpoints: &Endpoints,
    work_dir: &Path,
    name: &str,
    pkg: &Package,
    tag: &str,
) -> Result<FetchVerifyResult> {
    let version = checker::version_from_tag(tag).to_string();
    let asset_name = pkg.asset_pattern.replace("{version}", &version);
    let dest_dir = work_dir.join(name).join(tag);

    let api = endpoints.api();
    let asset = fetcher::download_asset(client, api, &pkg.repo, tag, &asset_name, &dest_dir)?;
    let verification = verifier::verify(
        client,
        api,
        &pkg.verification,
        &pkg.repo,
        tag,
        &asset.path,
        &dest_dir,
    )?;

    Ok(FetchVerifyResult {
        version,
        asset_name,
        dest_dir,
        asset,
        verification,
    })
}

fn build_and_publish(
    name: &str,
    pkg: &Package,
    tag: &str,
    fetched: &FetchVerifyResult,
) -> Result<()> {
    // Fail fast if the repo isn't registered in pacman.conf, before
    // spending several seconds on a makepkg build that would otherwise
    // succeed and then publish somewhere pacman never syncs from.
    let repo_dir = custom_repo_dir()?;
    publisher::ensure_registered(CUSTOM_REPO_NAME, &repo_dir)?;

    let build_dir = fetched.dest_dir.join("build");
    let req = builder::BuildRequest {
        pkg_name: name,
        pkg,
        version: &fetched.version,
        repo: &pkg.repo,
        asset_name: &fetched.asset_name,
        download_url: &fetched.asset.download_url,
        artifact_path: &fetched.asset.path,
    };
    let built = builder::build(&req, &build_dir)?;
    println!("  built {}", built.package_path.display());

    if let Some(check) = &pkg.sanity_check {
        let bin_dir = built.pkgdir.join("usr/bin");
        sanity::run(check, &bin_dir, &fetched.version)
            .with_context(|| format!("sanity check for {name} {tag}"))?;
        println!("  sanity check passed");
    }

    let published = publisher::publish(&built.package_path, &repo_dir, CUSTOM_REPO_NAME)?;
    println!(
        "  added to {} repo: {}",
        CUSTOM_REPO_NAME,
        published.display()
    );
    println!(
        "  not installed automatically — run `sudo pacman -Syu` (or `sudo pacman -S {name}`) to pick it up"
    );
    Ok(())
}

pub fn run_review(args: &[String]) -> Result<()> {
    let Paths {
        packages_dir,
        state_dir,
        work_dir,
    } = Paths::from_env()?;
    let packages = load_packages(&packages_dir)?;

    match args {
        [] => {
            let mut any = false;
            for (name, _) in &packages {
                if let Some(pending) = state::load_pending_version(&state_dir, name) {
                    println!(
                        "{name}: {pending} pending review (run `pkgwatch review {name} --approve`)"
                    );
                    any = true;
                }
            }
            if !any {
                println!("no packages pending review");
            }
            Ok(())
        }
        [name, flag] if flag == "--approve" => {
            let (_, pkg) = packages.iter().find(|(n, _)| n == name).with_context(|| {
                format!("no package named '{name}' in {}/", packages_dir.display())
            })?;
            let tag = state::load_pending_version(&state_dir, name)
                .with_context(|| format!("'{name}' has no pending review"))?;
            approve(&state_dir, &work_dir, name, pkg, &tag)
        }
        _ => bail!("usage: pkgwatch review [<name> --approve]"),
    }
}

fn approve(state_dir: &Path, work_dir: &Path, name: &str, pkg: &Package, tag: &str) -> Result<()> {
    let client = build_client()?;
    let endpoints = Endpoints::for_package(pkg)?;

    // Re-verify rather than trusting the earlier flag: the artifact at
    // this tag could in principle have changed since it was queued.
    let fetched = fetch_and_verify(&client, &endpoints, work_dir, name, pkg, tag)?;
    if !fetched.verification.passed {
        bail!(
            "re-verification failed on approve: {}",
            fetched.verification.justification
        );
    }
    println!(
        "re-verified (tier {}): {}",
        fetched.verification.tier, fetched.verification.justification
    );

    build_and_publish(name, pkg, tag, &fetched)?;
    state::save_last_version(state_dir, name, tag)?;
    state::clear_pending_version(state_dir, name)?;
    println!("approved and published {name} {tag}");
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::github::GithubEndpoints;
    use crate::test_support::same_origin_package;

    #[test]
    fn decide_tier_action_failed_verification_overrides_everything() {
        assert_eq!(
            decide_tier_action(2, false, false),
            TierAction::VerificationFailed
        );
        assert_eq!(
            decide_tier_action(4, false, true),
            TierAction::VerificationFailed
        );
    }

    #[test]
    fn decide_tier_action_tier_1_to_3_publishes() {
        assert_eq!(decide_tier_action(1, true, false), TierAction::Publish);
        assert_eq!(decide_tier_action(2, true, false), TierAction::Publish);
        assert_eq!(decide_tier_action(3, true, true), TierAction::Publish);
    }

    #[test]
    fn decide_tier_action_tier_4_to_6_newly_pending_when_not_seen_before() {
        assert_eq!(decide_tier_action(4, true, false), TierAction::NewlyPending);
        assert_eq!(decide_tier_action(6, true, false), TierAction::NewlyPending);
    }

    #[test]
    fn decide_tier_action_tier_4_to_6_still_pending_when_already_flagged() {
        assert_eq!(decide_tier_action(4, true, true), TierAction::StillPending);
    }

    /// Mocks the release-tag, asset, and checksum endpoints for `o/r@v1.0.0`
    /// with a checksum that doesn't match the asset, so verification fails.
    /// These are identical on GitHub and Forgejo (see `Endpoints::api`); only
    /// how the latest tag is found differs per test. Returned mocks must
    /// stay alive for the test's duration.
    fn mock_release_with_bad_checksum(server: &mut mockito::ServerGuard) -> Vec<mockito::Mock> {
        let asset_url = format!("{}/download/thing.tar.gz", server.url());
        let sums_url = format!("{}/download/SHA256SUMS", server.url());
        let release_body = format!(
            r#"{{"assets": [
                {{"name": "thing.tar.gz", "browser_download_url": "{asset_url}"}},
                {{"name": "SHA256SUMS", "browser_download_url": "{sums_url}"}}
            ]}}"#
        );
        vec![
            server
                .mock("GET", "/repos/o/r/releases/tags/v1.0.0")
                .with_status(200)
                .with_body(release_body)
                .create(),
            server
                .mock("GET", "/download/thing.tar.gz")
                .with_status(200)
                .with_body(b"artifact-bytes".as_slice())
                .create(),
            // Wrong hash for "artifact-bytes" — forces a verification failure.
            server
                .mock("GET", "/download/SHA256SUMS")
                .with_status(200)
                .with_body(
                    "0000000000000000000000000000000000000000000000000000000000000000  thing.tar.gz\n",
                )
                .create(),
        ]
    }

    /// Runs `process_package` for a package whose checksum is wrong and
    /// asserts it errors with "verification failed" while leaving no trace
    /// in state.
    fn assert_verification_failure_is_an_error(endpoints: &Endpoints, pkg: &Package) {
        let client = reqwest::blocking::Client::new();
        let state_dir = tempfile::tempdir().unwrap();
        let work_dir = tempfile::tempdir().unwrap();

        let err = process_package(
            &client,
            endpoints,
            state_dir.path(),
            work_dir.path(),
            "thing",
            pkg,
        )
        .unwrap_err();

        assert!(err.to_string().contains("verification failed"));
        // Neither published nor queued for review — a failed verification
        // shouldn't leave any trace in state.
        assert_eq!(state::load_last_version(state_dir.path(), "thing"), None);
        assert_eq!(state::load_pending_version(state_dir.path(), "thing"), None);
    }

    /// Regression test for the exit-code gap this PR fixes: a verification
    /// failure previously returned `Ok(())` from `process_package`, so
    /// `run_check` never counted it as a failure and the process exited 0
    /// even though the single most security-relevant check had failed.
    /// Exercises the full check -> fetch -> verify path against a mocked
    /// GitHub (no real network), stopping before any build/publish step
    /// since verification failure returns before reaching those.
    #[test]
    fn process_package_returns_err_on_verification_failure() {
        let mut server = mockito::Server::new();
        let endpoints = Endpoints::Github(GithubEndpoints {
            web: server.url(),
            api: server.url(),
        });
        let feed = format!(
            r#"<feed><link rel="alternate" href="{}/o/r/releases/tag/v1.0.0"/></feed>"#,
            server.url()
        );
        let _atom = server
            .mock("GET", "/o/r/releases.atom")
            .with_status(200)
            .with_body(feed)
            .create();
        let _release_mocks = mock_release_with_bad_checksum(&mut server);

        assert_verification_failure_is_an_error(&endpoints, &same_origin_package(""));
    }

    /// Same as above but through a Forgejo source, proving the whole
    /// check -> fetch -> verify path works there too: the error is the
    /// verification failure, not a fetch or check failure on the way to it.
    #[test]
    fn process_package_returns_err_on_verification_failure_via_forgejo() {
        let mut server = mockito::Server::new();
        let endpoints = Endpoints::Forgejo { api: server.url() };
        let _latest = server
            .mock("GET", "/repos/o/r/releases/latest")
            .with_status(200)
            .with_body(r#"{"tag_name": "v1.0.0"}"#)
            .create();
        let _release_mocks = mock_release_with_bad_checksum(&mut server);

        // The package's own `source` is irrelevant here: `endpoints` is
        // hand-built to point at the mock server, bypassing `for_package`.
        assert_verification_failure_is_an_error(&endpoints, &same_origin_package(""));
    }
}