#!/usr/bin/env bash
#
# Orb setup for idx-cli.
#
# A fresh orb has no Rust toolchain and no Nix, while the repository builds and
# verifies through its flake dev shell (`nix develop`). This script installs Nix
# (single-user), realizes the dev shell, makes that environment available to the
# login shells Amp and orb services start, and warms the Cargo build so the
# first agent command is incremental.
#
# Idempotent by design: an orb restored from a stale snapshot re-runs this and
# keeps /nix, ~/.cargo, and target/ instead of rebuilding them.
set -euo pipefail

repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
nix_profile="$HOME/.nix-profile"
nix_bin="$nix_profile/bin/nix"
nix_conf="$HOME/.config/nix/nix.conf"
bash_profile="$HOME/.bash_profile"
agent_guidance="$HOME/.config/amp/AGENTS.md"
profile_marker="# idx-cli orb dev shell (managed by .agents/setup)"
guidance_marker="<!-- idx-cli orb setup -->"

step() { printf '\n==> %s\n' "$*"; }

# Runs "$@" with timing so setup.log shows which step is slow or failing.
run() {
  local label="$1"
  shift
  local start=$SECONDS
  if "$@"; then
    printf '    ok: %s (%ss)\n' "$label" "$((SECONDS - start))"
    return 0
  fi
  local status=$?
  printf '    FAILED: %s (%ss, exit %s)\n' "$label" "$((SECONDS - start))" "$status" >&2
  return "$status"
}

# Warm-up work whose failure should not stop snapshot publication.
run_warn() {
  if ! run "$@"; then
    printf 'warning: %s failed; rerun .agents/setup once the cause is fixed\n' "$1" >&2
  fi
}

step "Nix package manager"
if [ -x "$nix_bin" ]; then
  printf '    ok: already installed (%s)\n' "$("$nix_bin" --version)"
else
  installer="$(mktemp)"
  curl -fsSL https://nixos.org/nix/install -o "$installer"
  run "install nix (single-user)" sh "$installer" --no-daemon --no-modify-profile --yes
  rm -f "$installer"
fi

# The installer cannot update the environment of this already-running script.
# shellcheck source=/dev/null
if [ -f "$nix_profile/etc/profile.d/nix.sh" ]; then
  . "$nix_profile/etc/profile.d/nix.sh"
fi

step "Nix flake support"
mkdir -p "$(dirname "$nix_conf")"
touch "$nix_conf"
if ! grep -qE '^[[:space:]]*experimental-features[[:space:]]*=.*nix-command' "$nix_conf"; then
  printf 'experimental-features = nix-command flakes\n' >>"$nix_conf"
fi
if ! grep -qE '^[[:space:]]*warn-dirty[[:space:]]*=' "$nix_conf"; then
  printf 'warn-dirty = false\n' >>"$nix_conf"
fi
printf '    ok: %s\n' "$nix_conf"

step "Flake dev shell"
run "realize dev shell" "$nix_bin" develop --command true

step "Warm Cargo build (kept in the snapshot for the first agent command)"
run_warn "cargo build --locked" "$nix_bin" develop --command bash -c 'cargo build --locked'
run_warn "cargo test --no-run --locked" "$nix_bin" develop --command bash -c 'cargo test --no-run --locked'
run_warn "cargo clippy --locked -- -D warnings" "$nix_bin" develop --command bash -c 'cargo clippy --locked -- -D warnings'

step "Login shell environment"
# Amp starts its login shells (the headless executor and orb services) from /,
# so activate the dev shell by repository path instead of by $PWD. The
# IN_NIX_SHELL guard keeps nested shells and `nix develop` itself cheap.
profile_hook() {
  cat <<EOF
$profile_marker
if [ -f "$nix_profile/etc/profile.d/nix.sh" ]; then
  # shellcheck disable=SC1091
  . "$nix_profile/etc/profile.d/nix.sh"
fi
if [ -z "\${IN_NIX_SHELL:-}" ] && [ -f "$repo_root/flake.nix" ]; then
  eval "\$("$nix_bin" print-dev-env "$repo_root")"
fi
if [ "\$PWD" = "$repo_root" ]; then
  case ":\$PATH:" in
    *":$repo_root/target/debug:"*) ;;
    *) PATH="$repo_root/target/debug:\$PATH" ;;
  esac
  export PATH
fi
EOF
}

if grep -Fqx "$profile_marker" "$bash_profile" 2>/dev/null; then
  printf '    ok: dev shell hook already present in %s\n' "$bash_profile"
else
  printf '\n' >>"$bash_profile"
  profile_hook >>"$bash_profile"
  printf '    ok: added dev shell hook to %s\n' "$bash_profile"
fi

step "Orb guidance for agents"
mkdir -p "$(dirname "$agent_guidance")"
if grep -Fq "$guidance_marker" "$agent_guidance" 2>/dev/null; then
  printf '    ok: guidance already present in %s\n' "$agent_guidance"
else
  cat >>"$agent_guidance" <<EOF

$guidance_marker
# idx-cli inside the orb

- The idx-cli Nix dev shell is already active for login shells: \`cargo\`, \`rustc\`, \`cargo clippy\`, \`cargo fmt\`, \`cargo nextest\`, \`prek\`, \`mutool\`, and the \`curl_chrome*\` binaries are on \`PATH\`.
- \`.agents/setup\` already ran \`cargo build --locked\`, so \`target/\` is warm; run \`cargo build\`, \`cargo clippy -- -D warnings\`, and \`cargo test\` directly.
- \`nix develop\` still works when you want the shell explicitly.
EOF
  printf '    ok: added orb guidance to %s\n' "$agent_guidance"
fi

step "Verify"
# A minimal environment proves the hook works for the login shells Amp starts,
# not just for this script's already-modified environment.
if run "cargo resolves in a clean login shell" \
  env -i HOME="$HOME" USER="${USER:-user}" PATH=/usr/bin:/bin /bin/bash -lc 'command -v cargo && cargo --version'; then
  printf '    ok: orb environment ready\n'
else
  printf 'error: the Nix dev shell is not active in a clean login shell\n' >&2
  exit 1
fi