alef 0.84.1

use crate::core::config::{Language, ResolvedCrateConfig};
use anyhow::Context as _;
use std::sync::LazyLock;
use tracing::{debug, info, warn};

/// Matches a `checksum: "..."` field in `Package.swift` whose value is either the
/// unsubstituted placeholder or a previously-substituted 64-hex-char SHA-256 literal --
/// the only two shapes this field is ever in, since alef is the sole writer of it.
/// Capturing the surrounding `checksum: "` / `"` lets the replacement preserve the exact
/// original spacing rather than re-deriving it. ~keep
static SWIFT_CHECKSUM_FIELD_RE: LazyLock<regex::Regex> = LazyLock::new(|| {
    regex::Regex::new(r#"(checksum:\s*")(?:__ALEF_SWIFT_CHECKSUM__|[0-9a-f]{64})(")"#).expect("valid regex")
});

fn run_argv_captured(program: &str, args: &[&std::ffi::OsStr]) -> anyhow::Result<(String, String)> {
    let output = std::process::Command::new(program).args(args).output()?;
    if !output.status.success() {
        anyhow::bail!("{program} exited with {}", output.status.code().unwrap_or(-1));
    }
    Ok((
        String::from_utf8_lossy(&output.stdout).into_owned(),
        String::from_utf8_lossy(&output.stderr).into_owned(),
    ))
}

/// Sync generated SwiftPM version pins for this crate's first-party package, whichever shape a
/// consumer's manifest declares them in (`from: "X.Y.Z"` or `branch: "release/swift/X.Y.Z"` --
/// see [`super::version_text::sync_swift_first_party_from`]).
///
/// Generated test app and e2e manifests may include external SwiftPM packages.
/// Only the dependency whose URL points at this repo should track the workspace
/// version; external pins must stay untouched.
pub(super) fn sync_swift_package_versions(
    config: &ResolvedCrateConfig,
    version: &str,
    writable: &crate::cli::git::IgnoreFilter,
    updated: &mut Vec<String>,
) -> anyhow::Result<()> {
    let Some(repo_url) = config.try_github_repo().ok() else {
        return Ok(());
    };

    for swift_pkg_pattern in &["test_apps/*/Package.swift", "e2e/*/Package.swift"] {
        for swift_pkg in writable.glob(swift_pkg_pattern) {
            if let Ok(content) = std::fs::read_to_string(&swift_pkg)
                && let Some(new_content) =
                    super::version_text::sync_swift_first_party_from(&content, &repo_url, version)
            {
                std::fs::write(&swift_pkg, &new_content)
                    .with_context(|| format!("failed to write {}", swift_pkg.display()))?;
                updated.push(swift_pkg.to_string_lossy().to_string());
            }
        }
    }

    Ok(())
}

/// Build the swift artifactbundle for the current crate, compute its sha256,
/// substitute `__ALEF_SWIFT_CHECKSUM__` in root `Package.swift`, and write a
/// sidecar file at `target/alef-swift-checksum.txt` so the publish workflow can
/// reuse the checksum without rebuilding.
///
/// # Steps
///
/// 1. Detect whether the workspace has a swift binding crate (`{name}-swift`).
///    Skip with a warning if not found.
/// 2. Look for a pre-built `.artifactbundle.zip` under `dist/swift-artifactbundle/`.
///    If none exists, shell out to `cargo build -p {crate}-swift --release` and
///    the alef-bundled build script to produce one.  Skips gracefully when the
///    build prerequisites (Xcode / Apple targets) are absent.
/// 3. Compute the checksum with `swift package compute-checksum {zip}` (falls back
///    to a SHA-256 hex digest computed in-process if `swift` is not on PATH).
/// 4. Substitute the checksum in `Package.swift` and write the sidecar file.
///
/// Substitution is idempotent in both directions: it rewrites the `checksum:` field
/// whether it currently holds the placeholder *or* an already-substituted literal from a
/// previous release. It must never be one-way -- a one-way substitution destroys its own
/// trigger the moment a real checksum lands on `main`, so every release after the first
/// silently no-ops forever. This is not hypothetical: it happened in a real downstream crate, where
/// `e1d2b2293` injected a literal checksum for v1.4.0 and nothing ever restored the
/// placeholder afterward, so every `release/swift/*` branch and checksum substitution
/// after that commit silently skipped while reporting success. ~keep
///
/// Returns `Ok(Some(checksum))` when substitution succeeds, `Ok(None)` when skipped for a
/// legitimate reason (Swift not configured, no swift binding crate, or build prerequisites
/// absent), and `Err` when `Package.swift` exists but has no `checksum:` field matching
/// either recognized shape -- that state means the file's format has drifted underneath
/// this function and silently proceeding would hide it.
pub(super) fn precompute_swift_checksum(config: &ResolvedCrateConfig) -> anyhow::Result<Option<String>> {
    let pkg_swift_path = std::path::Path::new("Package.swift");
    let pkg_content = match std::fs::read_to_string(pkg_swift_path) {
        Ok(c) => c,
        Err(_) => {
            debug!("Package.swift not found — skipping swift checksum precompute");
            return Ok(None);
        }
    };
    if !config.languages.contains(&Language::Swift) {
        debug!("Swift not configured — skipping swift checksum precompute");
        return Ok(None);
    }

    let swift_crate = format!("{}-swift", config.name);
    let candidate_manifests = [
        format!("crates/{swift_crate}/Cargo.toml"),
        "packages/swift/rust/Cargo.toml".to_string(),
    ];
    let swift_manifest = candidate_manifests
        .iter()
        .find(|p| std::path::Path::new(p).exists())
        .cloned();
    let Some(swift_manifest) = swift_manifest else {
        warn!(
            "Swift binding crate `{swift_crate}` not found under any of {:?} — \
             skipping checksum precompute. Run with --skip-swift-checksum to suppress.",
            candidate_manifests
        );
        return Ok(None);
    };
    debug!("Using swift manifest: {swift_manifest}");

    let bundle_dir = std::path::Path::new("dist/swift-artifactbundle");
    let existing_zip = if bundle_dir.exists() {
        std::fs::read_dir(bundle_dir).ok().and_then(|entries| {
            entries
                .filter_map(|e| e.ok())
                .map(|e| e.path())
                .find(|p| p.extension().and_then(|e| e.to_str()) == Some("zip"))
        })
    } else {
        None
    };

    let zip_path = match existing_zip {
        Some(p) => {
            info!("Using pre-built artifactbundle: {}", p.display());
            p
        }
        None => {
            info!("Building swift artifactbundle for `{swift_crate}`…");
            let args = [
                std::ffi::OsStr::new("build"),
                std::ffi::OsStr::new("-p"),
                std::ffi::OsStr::new(&swift_crate),
                std::ffi::OsStr::new("--release"),
                std::ffi::OsStr::new("--target"),
                std::ffi::OsStr::new("aarch64-apple-darwin"),
            ];
            match run_argv_captured("cargo", &args) {
                Ok(_) => {}
                Err(e) => {
                    // Fires on every non-macOS host and every pre-release repo without Xcode; a
                    // correct setup lacking Apple tooling cannot avoid this. ~keep
                    info!(
                        "Swift artifactbundle build failed (missing Xcode / Apple targets?): {e}\n\
                         Re-run with --skip-swift-checksum to skip this step."
                    );
                    return Ok(None);
                }
            }
            std::fs::create_dir_all(bundle_dir).ok();
            match std::fs::read_dir(bundle_dir).ok().and_then(|entries| {
                entries
                    .filter_map(|e| e.ok())
                    .map(|e| e.path())
                    .find(|p| p.extension().and_then(|e| e.to_str()) == Some("zip"))
            }) {
                Some(p) => p,
                None => {
                    // Downstream of the artifactbundle build above; a correct setup without Xcode
                    // / Apple targets reaches this on every non-macOS host. ~keep
                    info!(
                        "No .zip found in `dist/swift-artifactbundle/` after build — \
                         skipping checksum substitution."
                    );
                    return Ok(None);
                }
            }
        }
    };

    let args = [
        std::ffi::OsStr::new("package"),
        std::ffi::OsStr::new("compute-checksum"),
        zip_path.as_os_str(),
    ];
    let checksum = match run_argv_captured("swift", &args) {
        Ok((stdout, _)) => stdout.trim().to_string(),
        Err(_) => {
            info!("`swift` not found — computing SHA-256 in-process");
            let bytes = std::fs::read(&zip_path).with_context(|| format!("failed to read {}", zip_path.display()))?;
            compute_sha256_hex(&bytes)
        }
    };

    if checksum.is_empty() {
        // Downstream of the artifactbundle build above; a correct setup without Xcode / Apple
        // targets reaches this on every non-macOS host. ~keep
        info!("Computed empty checksum — skipping substitution");
        return Ok(None);
    }

    // Assert the substitution will actually change something before performing it, rather than
    // asserting the placeholder's absence afterward -- an absence check is satisfied both by a
    // real substitution and by this field disappearing/renaming underneath us, which is exactly
    // the failure this must catch instead of silently swallow. ~keep
    let checksum_field_matches = SWIFT_CHECKSUM_FIELD_RE.find_iter(&pkg_content).count();
    if checksum_field_matches == 0 {
        anyhow::bail!(
            "Package.swift has no `checksum:` field holding `__ALEF_SWIFT_CHECKSUM__` or a 64-hex-char \
             literal — cannot substitute the computed checksum"
        );
    }

    let new_content = SWIFT_CHECKSUM_FIELD_RE
        .replace_all(&pkg_content, format!("${{1}}{checksum}$2").as_str())
        .into_owned();
    std::fs::write(pkg_swift_path, &new_content).context("writing Package.swift with checksum")?;
    info!("Substituted checksum → {checksum} in Package.swift ({checksum_field_matches} field(s))");

    std::fs::create_dir_all("target").ok();
    std::fs::write("target/alef-swift-checksum.txt", &checksum).context("writing target/alef-swift-checksum.txt")?;

    Ok(Some(checksum))
}

/// Compute a lowercase hex SHA-256 digest of `bytes` without shelling out.
///
/// Used as a fallback when `swift package compute-checksum` is not available.
pub(super) fn compute_sha256_hex(bytes: &[u8]) -> String {
    use std::num::Wrapping;

    const K: [u32; 64] = [
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98,
        0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
        0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8,
        0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
        0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819,
        0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
        0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7,
        0xc67178f2,
    ];

    let mut h: [Wrapping<u32>; 8] = [
        Wrapping(0x6a09e667),
        Wrapping(0xbb67ae85),
        Wrapping(0x3c6ef372),
        Wrapping(0xa54ff53a),
        Wrapping(0x510e527f),
        Wrapping(0x9b05688c),
        Wrapping(0x1f83d9ab),
        Wrapping(0x5be0cd19),
    ];

    let bit_len = (bytes.len() as u64).wrapping_mul(8);
    let mut msg = bytes.to_vec();
    msg.push(0x80);
    while msg.len() % 64 != 56 {
        msg.push(0x00);
    }
    msg.extend_from_slice(&bit_len.to_be_bytes());

    for chunk in msg.as_chunks::<64>().0 {
        let mut w = [Wrapping(0u32); 64];
        for i in 0..16 {
            w[i] = Wrapping(u32::from_be_bytes([
                chunk[i * 4],
                chunk[i * 4 + 1],
                chunk[i * 4 + 2],
                chunk[i * 4 + 3],
            ]));
        }
        for i in 16..64 {
            let s0 = w[i - 15].0.rotate_right(7) ^ w[i - 15].0.rotate_right(18) ^ (w[i - 15].0 >> 3);
            let s1 = w[i - 2].0.rotate_right(17) ^ w[i - 2].0.rotate_right(19) ^ (w[i - 2].0 >> 10);
            w[i] = w[i - 16] + Wrapping(s0) + w[i - 7] + Wrapping(s1);
        }
        let [mut a, mut b, mut c, mut d, mut e, mut f, mut g, mut hh] = h;
        for i in 0..64 {
            let s1 = e.0.rotate_right(6) ^ e.0.rotate_right(11) ^ e.0.rotate_right(25);
            let ch = (e.0 & f.0) ^ ((!e.0) & g.0);
            let temp1 = hh + Wrapping(s1) + Wrapping(ch) + Wrapping(K[i]) + w[i];
            let s0 = a.0.rotate_right(2) ^ a.0.rotate_right(13) ^ a.0.rotate_right(22);
            let maj = (a.0 & b.0) ^ (a.0 & c.0) ^ (b.0 & c.0);
            let temp2 = Wrapping(s0) + Wrapping(maj);
            hh = g;
            g = f;
            f = e;
            e = d + temp1;
            d = c;
            c = b;
            b = a;
            a = temp1 + temp2;
        }
        h[0] += a;
        h[1] += b;
        h[2] += c;
        h[3] += d;
        h[4] += e;
        h[5] += f;
        h[6] += g;
        h[7] += hh;
    }

    format!(
        "{:08x}{:08x}{:08x}{:08x}{:08x}{:08x}{:08x}{:08x}",
        h[0].0, h[1].0, h[2].0, h[3].0, h[4].0, h[5].0, h[6].0, h[7].0
    )
}