#!/usr/bin/env bash
# Validation entry point for CI and local/agent review.
#
# Default mode (what CI runs on every push/PR): fmt-check, statix, and eval
# are scoped to files that actually changed against a base ref, plus
# whichever hosts/packages those changes can affect. This exists because
# the unscoped sweep below is slow enough to time out CI runners -- see
# --full-check.
#
# --full-check: the historical full sweep (every host, every package,
# fmt --check ./statix check . over the whole tree). Slow -- minutes, not
# seconds. CI never passes this; run it locally before a release or after
# touching modules/common/*, flake.nix, or variables.nix if you want extra
# confidence beyond what the changed-files scope already covers for those
# paths (see below).
#
# --dry-run: adds `nix build --dry-run --no-link` for whatever scope is
# active (changed-files scope by default, full scope under --full-check).
set -euo pipefail

script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
# shellcheck source=lib/nix-bootstrap.sh
source "${script_dir}/lib/nix-bootstrap.sh"
# shellcheck source=lib/nix-eval.sh
source "${script_dir}/lib/nix-eval.sh"

repo_root="$(cd "${script_dir}/.." && pwd)"
cd "$repo_root"

full_check=false
dry_run=false

usage() {
  cat <<'EOF'
Usage: scripts/codex-maintenance.sh [--full-check] [--dry-run]

  --full-check  Run the full sweep: fmt-check and statix over the whole
                repo, eval every host and package. Slow. Never run by CI.
  --dry-run     Additionally run `nix build --dry-run --no-link` for
                whatever scope is active.

With neither flag (the CI default), fmt-check/statix/eval are scoped to
files changed against a base ref (env MAINT_BASE_SHA, else the PR base,
else HEAD^), plus the hosts/packages those changes can affect.
EOF
}

for arg in "$@"; do
  case "$arg" in
    --full-check) full_check=true ;;
    --dry-run) dry_run=true ;;
    -h|--help) usage; exit 0 ;;
    *)
      echo "Unknown argument: $arg" >&2
      usage >&2
      exit 1
      ;;
  esac
done

ensure_nix_profile

if ! command -v nix >/dev/null 2>&1; then
  echo "ERROR: nix is not available in PATH. Run bash scripts/codex-setup.sh first." >&2
  exit 127
fi

echo "Checking for obvious committed secrets..."
if grep -RInE 'github_pat_|ghp_|access-tokens|hashedPassword[[:space:]]*=' \
  --exclude-dir=.git \
  --exclude=flake.lock \
  .; then
  echo
  echo "WARNING: Potential secrets or password hashes found. Review before committing."
else
  echo "No obvious token patterns found."
fi

mapfile -t all_hosts < <(list_flake_targets .)
mapfile -t all_packages < <(nix eval --json "${NIX_EVAL_FLAGS[@]}" .#packages.x86_64-linux --apply builtins.attrNames | jq -r '.[]')

# host_targets_for_dir <hosts-subdir-name>
# Prints the nixosConfigurations target names whose hostPath is
# ./hosts/<dir>/host.nix, derived straight from flake.nix's generatedTargets
# (one mkTarget { ... } call per line) rather than a hand-maintained table,
# so it can't drift the way a copied mapping would.
host_targets_for_dir() {
  local dir="$1"
  grep -oE '^[[:space:]]*[A-Za-z0-9_-]+ = mkTarget \{[^}]*hostPath = \./hosts/'"${dir}"'/host\.nix;[^}]*\};' flake.nix \
    | sed -E 's/^[[:space:]]*([A-Za-z0-9_-]+) = mkTarget.*/\1/' \
    || true
}

declare -a changed_files=()
scope_desc="full repo"

if ! $full_check; then
  resolve_base_ref() {
    if [[ -n "${MAINT_BASE_SHA:-}" ]] && git cat-file -e "${MAINT_BASE_SHA}^{commit}" 2>/dev/null; then
      echo "$MAINT_BASE_SHA"
      return
    fi
    if git rev-parse --verify -q HEAD^ >/dev/null 2>&1; then
      echo "HEAD^"
      return
    fi
    git hash-object -t tree /dev/null
  }

  base_ref="$(resolve_base_ref)"
  echo
  echo "Changed-files scope: diffing against ${base_ref}"
  mapfile -t changed_files < <(git diff --name-only --diff-filter=ACMR "$base_ref" -- . | sort -u)

  if [[ ${#changed_files[@]} -eq 0 ]]; then
    echo "No changed files detected."
  else
    printf '  %s\n' "${changed_files[@]}"
  fi
  scope_desc="changed files only (base: ${base_ref})"
fi

# Whole-tree fmt/lint always run under --full-check; otherwise scoped below.
declare -a changed_nix_files=()
for f in "${changed_files[@]:-}"; do
  [[ "$f" == *.nix && -f "$f" ]] && changed_nix_files+=("$f")
done

echo
echo "Checking Nix formatting with nixpkgs-fmt..."
if $full_check; then
  nix run "${NIX_EVAL_FLAGS[@]}" github:NixOS/nixpkgs/nixos-25.11#nixpkgs-fmt -- --check .
elif [[ ${#changed_nix_files[@]} -gt 0 ]]; then
  nix run "${NIX_EVAL_FLAGS[@]}" github:NixOS/nixpkgs/nixos-25.11#nixpkgs-fmt -- --check "${changed_nix_files[@]}"
else
  echo "No changed .nix files; skipping."
fi

echo
echo "Running statix lint..."
if $full_check; then
  nix run "${NIX_EVAL_FLAGS[@]}" github:NixOS/nixpkgs/nixos-25.11#statix -- check .
elif [[ ${#changed_nix_files[@]} -gt 0 ]]; then
  for f in "${changed_nix_files[@]}"; do
    nix run "${NIX_EVAL_FLAGS[@]}" github:NixOS/nixpkgs/nixos-25.11#statix -- check "$f"
  done
else
  echo "No changed .nix files; skipping."
fi

# Figure out which hosts/packages this run needs to eval (and, under
# --dry-run, build). full_check always means "everything"; otherwise a
# change to flake.nix/flake.lock/variables.nix/modules/common/* (repo-wide
# inputs) or to any other modules/*.nix outside platforms//build-types
# (whose blast radius isn't safely inferable from the path alone -- see
# CLAUDE.md's "Grep modules/build-types/*.nix for each build type's imports
# list") also falls back to everything, on the same reasoning CLAUDE.md
# already gives interactive sessions for when to run the full sweep.
# Anything more targeted -- a host.nix, a platform module, a build-type
# module -- narrows to just the hosts it can affect.
declare -A affected_hosts=()
eval_packages=false

if $full_check; then
  for h in "${all_hosts[@]}"; do affected_hosts[$h]=1; done
  eval_packages=true
else
  full_fallback=false
  for f in "${changed_files[@]:-}"; do
    case "$f" in
      flake.nix|flake.lock|variables.nix|modules/common/*)
        full_fallback=true
        ;;
    esac
  done

  if ! $full_fallback; then
    for f in "${changed_files[@]:-}"; do
      case "$f" in
        hosts/*/*)
          hostdir="${f#hosts/}"
          hostdir="${hostdir%%/*}"
          while IFS= read -r t; do
            [[ -n "$t" ]] && affected_hosts[$t]=1
          done < <(host_targets_for_dir "$hostdir")
          ;;
        modules/platforms/*.nix)
          platform="$(basename "$f" .nix)"
          for h in "${all_hosts[@]}"; do
            [[ "$h" == "${platform}-"* ]] && affected_hosts[$h]=1
          done
          ;;
        modules/build-types/*.nix)
          buildtype="$(basename "$f" .nix)"
          for h in "${all_hosts[@]}"; do
            [[ "$h" == *"-${buildtype}" ]] && affected_hosts[$h]=1
          done
          ;;
        modules/installer/*)
          # iso.nix (imported by both the "installer" nixosConfigurations
          # target and netbootSystem, which backs packages.pxe) pulls in
          # common.nix, so a common.nix change reaches all three.
          affected_hosts[installer]=1
          eval_packages=true
          ;;
        modules/pxe-boot/*)
          # stage-installer-artifacts.nix is imported by
          # modules/build-types/pxe-boot.nix only -- same blast radius as a
          # build-types/*.nix change, not a packages one.
          for h in "${all_hosts[@]}"; do
            [[ "$h" == *"-pxe-boot" ]] && affected_hosts[$h]=1
          done
          ;;
        modules/*)
          full_fallback=true
          ;;
      esac
    done
  fi

  if $full_fallback; then
    echo
    echo "Changed files affect shared config; falling back to evaluating every host/package."
    for h in "${all_hosts[@]}"; do affected_hosts[$h]=1; done
    eval_packages=true
  fi
fi

mapfile -t hosts < <(for h in "${!affected_hosts[@]}"; do echo "$h"; done | sort)

echo
echo "Checking nix-cache host key for drift..."
if bash "${script_dir}/secrets/sync-nix-cache-host-key.sh" --check; then
  :
else
  drift_status=$?
  if [[ "$drift_status" -eq 2 ]]; then
    echo "nix-cache unreachable from here -- skipping host-key drift check."
  else
    echo "WARNING: nix-cache's host key has drifted from variables.nix (see above)." >&2
    echo "  Run 'bash scripts/secrets/sync-nix-cache-host-key.sh' to fix." >&2
  fi
fi

echo
if [[ ${#hosts[@]} -eq 0 ]]; then
  echo "No hosts affected by changed files; skipping host eval."
else
  echo "Evaluating host toplevel derivations (${scope_desc})..."
  for host in "${hosts[@]}"; do
    echo "==> $host"
    nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.toplevel.drvPath"

    # lxc-* hosts deploy via a directly pct-restore-able tarball instead of
    # nixos-install (see docs/auto-installer.md); proxmox-* hosts can
    # alternatively be built as a standalone disk image (see
    # docs/proxmox-images.md). Both are otherwise-unvalidated buildable
    # surface, easy to silently break without this.
    case "$host" in
      lxc-*)
        echo "==> $host (tarball)"
        nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.tarball.drvPath"
        ;;
      proxmox-*)
        echo "==> $host (diskoImagesScript)"
        nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.diskoImagesScript.drvPath"
        ;;
    esac
  done
fi

echo
if ! $eval_packages; then
  echo "No packages affected by changed files; skipping package eval."
else
  echo "Evaluating buildable packages..."
  for pkg in "${all_packages[@]}"; do
    echo "==> packages.x86_64-linux.${pkg}"
    nix eval --raw "${NIX_EVAL_FLAGS[@]}" ".#packages.x86_64-linux.${pkg}"
  done
fi

if $dry_run; then
  echo
  echo "Running dry-run builds for the active scope. This will not create result symlinks."
  for host in "${hosts[@]:-}"; do
    echo "==> Dry-run build: $host"
    nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.toplevel"

    case "$host" in
      lxc-*)
        echo "==> Dry-run build: $host (tarball)"
        nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.tarball"
        ;;
      proxmox-*)
        echo "==> Dry-run build: $host (diskoImagesScript)"
        nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#nixosConfigurations.${host}.config.system.build.diskoImagesScript"
        ;;
    esac
  done

  if $eval_packages; then
    echo
    echo "Running dry-run builds for packages."
    for pkg in "${all_packages[@]}"; do
      echo "==> Dry-run build: packages.x86_64-linux.${pkg}"
      nix build --dry-run --no-link "${NIX_EVAL_FLAGS[@]}" ".#packages.x86_64-linux.${pkg}"
    done
  fi
fi

echo
echo "Maintenance checks complete."