#!/bin/sh
# `cf` on PATH, backed by whichever labs checkout you are standing in.
#
# Shell completion is why this exists: the function `cf completion bash|zsh`
# installs calls `cf completion complete` by name on every Tab, so completion
# is silently dead for anyone without a `cf` on PATH — including for
# `deno task cf <TAB>`, since the same function services the `deno` binding.
#
# Pick it up with `deno task install-cf`, which copies this file to a directory
# on PATH: that needs no binary built, and one copy serves every checkout.
#
# Runs from source, so it never goes stale against the checkout. `dist/cf` is
# deliberately not used here — see "Why not dist/cf" in packages/cli/README.md.

set -e

# Which labs checkout to run, in precedence order:
#
#   1. $CF_LABS_ROOT, if set — an explicit override for when the cwd cannot
#      say what you mean (working on a pattern in /tmp, say). A value that is
#      not a checkout is an error, not a quiet fall-through to something else.
#   2. The nearest checkout walking up from $PWD, so a symlinked install does
#      not pin `cf` to the checkout it was installed from. Several checkouts
#      coexisting is normal here — a vendored labs inside another repo is a
#      supported, tested layout (see packages/cli/test/launcher.test.ts).
#   3. A default chosen when this file was installed, then the checkout this
#      file physically lives in — for when you are not standing in one at all.
#      An installed copy carries the default; the in-repo file and any symlink
#      to it fall through to their own checkout. Neither applies while you are
#      inside a checkout, which is the overwhelmingly common case.
#
# Route 2 is what lets one installed copy serve every checkout: the copy has no
# checkout of its own, and the directory you stand in decides.

# Rewritten by scripts/install-cf.sh when it installs a copy. Empty here: the
# in-repo file is reached through a checkout by definition.
DEFAULT_LABS_ROOT=""

is_labs_checkout() {
  [ -f "${1}/packages/cli/launcher.ts" ]
}

# First match walking up wins. A directory is checked as a checkout before it
# is checked as a vendoring host, so standing inside `<host>/vendor/labs`
# selects that labs rather than walking up and re-deriving it from the host.
resolve_from_cwd() {
  dir=$PWD
  while :; do
    if is_labs_checkout "${dir}"; then
      printf '%s\n' "${dir}"
      return 0
    fi
    if is_labs_checkout "${dir}/vendor/labs"; then
      printf '%s\n' "${dir}/vendor/labs"
      return 0
    fi
    parent=$(dirname "${dir}")
    # dirname("/") is "/" — stop rather than spin.
    [ "${parent}" = "${dir}" ] && return 1
    dir=$parent
  done
}

# Resolve through symlinks so a linked install reports the checkout rather than
# the link. `readlink -f` is GNU and newer-macOS only, so the links are walked
# by hand to keep this working on a stock macOS shell. An installed copy is not
# a link and lands on its own directory, which is not a checkout — that is what
# DEFAULT_LABS_ROOT is for.
script_checkout() {
  target=$0
  while [ -L "${target}" ]; do
    link=$(readlink "${target}")
    case ${link} in
      /*) target=$link ;;
      *) target=$(dirname "${target}")/$link ;;
    esac
  done
  (CDPATH= cd -- "$(dirname -- "${target}")/.." && pwd -P)
}

# Last resort, in order: the root chosen at install time, then this file's own
# checkout. Both are skipped unless they really are checkouts, so a stale
# install-time default cannot silently send you somewhere that no longer exists.
fallback_root() {
  if [ -n "${DEFAULT_LABS_ROOT}" ] && is_labs_checkout "${DEFAULT_LABS_ROOT}"; then
    printf '%s\n' "${DEFAULT_LABS_ROOT}"
    return 0
  fi
  own=$(script_checkout)
  if is_labs_checkout "${own}"; then
    printf '%s\n' "${own}"
    return 0
  fi
  return 1
}

if [ -n "${CF_LABS_ROOT:-}" ]; then
  root=$CF_LABS_ROOT
  reason="CF_LABS_ROOT"
  if ! is_labs_checkout "${root}"; then
    echo "cf: CF_LABS_ROOT is not a labs checkout: ${root}" >&2
    echo "    (expected ${root}/packages/cli/launcher.ts to exist)" >&2
    exit 2
  fi
elif root=$(resolve_from_cwd); then
  reason="nearest checkout above the current directory"
elif root=$(fallback_root); then
  reason="fallback (not inside a checkout)"
else
  echo "cf: no labs checkout found." >&2
  echo "    Not inside one, and this install has no usable default." >&2
  echo "    cd into a checkout, set CF_LABS_ROOT, or re-run 'deno task install-cf'." >&2
  exit 2
fi

# Answered by the wrapper, never forwarded: the question is which CLI would run,
# so handing it to that CLI would beg it. Only as the first argument, so it
# cannot swallow a `which` meant as a value for some other command.
#
# stdout is the checkout, because that is the part that varies and what the
# question is really about — the entry inside it is always the same file. The
# entry and the reason go to stderr, matching the CLI's output conventions, so
# stdout stays a bare path a script can consume.
if [ "${1:-}" = "which" ]; then
  entry="${root}/packages/cli/mod.ts"
  printf '%s\n' "${root}"
  # The checkout test above only proves launcher.ts is there. The entry the
  # launcher then runs is a separate file, and reporting a path without
  # checking it would make `which` assert something it has not verified —
  # the one thing a diagnostic command must not do.
  if [ ! -f "${entry}" ]; then
    echo "cf: entry ${entry} does not exist — this checkout is incomplete" >&2
    echo "cf: selected by ${reason}" >&2
    exit 1
  fi
  echo "cf: entry ${entry}" >&2
  echo "cf: selected by ${reason}" >&2
  exit 0
fi

if ! command -v deno >/dev/null 2>&1; then
  echo "cf: deno not found on PATH." >&2
  echo "    Install it with mise (\`mise install\` in ${root}) or directly:" >&2
  echo "    https://docs.deno.com/runtime/getting_started/installation/" >&2
  exit 127
fi

# `--cwd "$PWD"` because the launcher otherwise prefers an inherited INIT_CWD,
# which is stale whenever `cf` is called from inside a `deno task`. `--` keeps
# launcher option parsing off the user's own arguments (`cf --config …`).
exec deno run --allow-run --allow-env --allow-read \
  "${root}/packages/cli/launcher.ts" --cwd "$PWD" -- "$@"