#!/usr/bin/env bash
# Craig Jennings <c@cjennings.net>
# Build & install Emacs from source
# safe, user-local, fast, versioned.

set -Eeuo pipefail
IFS=$'\n\t'

#  ------------------------ Config (overwrite via ENV) -----------------------

SRC_DIR="${SRC_DIR:-$HOME/code/emacs-src}"
EMACS_REPO="${EMACS_REPO:-https://git.savannah.gnu.org/git/emacs.git}"
CHECKOUT_REF="${CHECKOUT_REF:-emacs-30.2}"
# CHECKOUT_REF="${CHECKOUT_REF:-636f166cfc8}"
PREFIX_BASE="${PREFIX_BASE:-$HOME/.local/src/emacs}"
PREFIX="${PREFIX:-$PREFIX_BASE/${CHECKOUT_REF}}"
# LOG_DIR="${LOG_DIR:-$HOME/.cache/emacs-build-logs}"
LOG_DIR="${LOG_DIR:-$HOME/}"
ENABLE_NATIVE="${ENABLE_NATIVE:-1}"
# WITH_PGTK="${WITH_PGTK:-auto}"
WITH_PGTK="${WITH_PGTK:-0}"
JOBS="${JOBS:-auto}"
EXTRA_CONFIG="${EXTRA_CONFIG:-}"

#  --------------------------------- Preflight ---------------------------------

umask 022
mkdir -p "$LOG_DIR" "$PREFIX_BASE" "$HOME/.local/bin"
: "${LOGFILE:=$LOG_DIR/emacs-build-$(date +%Y%m%d-%H%M%S)-${CHECKOUT_REF}.log}"

say() { printf '>>> %s\n' "$*" | tee -a "$LOGFILE" ; }
run() {
	say "+ $*"
	if ! eval "$@" >>"$LOGFILE" 2>&1; then
		echo "ERROR: Command failed: $*" >&2
		echo "Last 20 lines of output:" >&2
		tail -n 20 "$LOGFILE" >&2
		return 1
	fi
}

on_err(){ 
    ec=$?
	echo "ERROR [$ec] - Full log at: $LOGFILE" >&2
	echo "Last 100 lines of log:" >&2
	tail -n 100 "$LOGFILE" >&2 || true
	exit "$ec"
}

trap on_err ERR

#  -------------------------- Arch Linux Dependencies --------------------------

if [[ -r /etc/os-release ]]; then
  . /etc/os-release
fi

if [[ "${ID:-}" == "arch" || "${ID_LIKE:-}" == *arch* ]]; then
  say "Arch Linux detected; checking required build/runtime packages"

  # Base packages needed for the requested configure flags
  pkgs=(jansson tree-sitter imagemagick mailutils harfbuzz cairo gnutls libxml2 texinfo gtk3)

  # Only if native-compilation is enabled
  if [[ "${ENABLE_NATIVE:-1}" == "1" ]]; then
	pkgs+=(libgccjit)
  fi

  # List packages that are not installed
  missing="$(pacman -T "${pkgs[@]}" || true)"

  if [[ -z "$missing" ]]; then
	say "All required packages are already installed."
  else
	say "Missing packages: $missing"
	if command -v sudo >/dev/null 2>&1 && sudo -n true 2>/dev/null; then
	  run "sudo -n pacman -Sy --needed --noconfirm $missing"
	else
	  say "sudo (passwordless) not available; please install missing packages manually:"
	  echo "  sudo pacman -Sy --needed $missing"
	  exit 70
	fi
  fi
else
  say "Non-Arch system detected; skipping Arch-specific dependency check."
fi

#  ----------------------------- Clone And Update ----------------------------

if [[ -d "$SRC_DIR/.git" ]]; then
  run "git -C '$SRC_DIR' fetch --tags --prune"
else
  mkdir -p "$(dirname "$SRC_DIR")"
  run "git clone --origin origin '$EMACS_REPO' '$SRC_DIR'"
fi

run "git -C '$SRC_DIR' reset --hard HEAD"
run "git -C '$SRC_DIR' clean -fdx"
run "git -C '$SRC_DIR' checkout -f '$CHECKOUT_REF'"
run "git -C '$SRC_DIR' submodule update --init --recursive || true"

#  ---------------------------------- Autogen ----------------------------------

if [[ -x "$SRC_DIR/autogen.sh" ]]; then
  run "cd '$SRC_DIR' && ./autogen.sh"
fi

#  ------------------------------ Configure Flags ------------------------------

conf_flags=(
  "--prefix=${PREFIX}"
  "--with-json"
  "--with-modules"
)

# Wayland/X choice
if [[ "$WITH_PGTK" == "auto" ]]; then
  if [[ -n "${WAYLAND_DISPLAY:-}" ]]; then WITH_PGTK="yes"; else WITH_PGTK="no"; fi
fi
if [[ "$WITH_PGTK" == "yes" ]]; then
  conf_flags+=("--with-pgtk")
else
  conf_flags+=("--with-x-toolkit=gtk3")
fi

# Native-compilation
if [[ "$ENABLE_NATIVE" == "1" ]]; then
  conf_flags+=("--with-native-compilation=yes")
else
  conf_flags+=("--with-native-compilation=no")
fi

# Useful extras (disable later via EXTRA_CONFIG if missing deps)
conf_flags+=(
  "--with-cairo"
  "--with-harfbuzz"
  "--with-tree-sitter"
  "--with-imagemagick"
  "--with-mailutils"
)

# Optional extra flags from env
if [[ -n "$EXTRA_CONFIG" ]]; then
  # shellcheck disable=SC2206
  conf_flags+=($EXTRA_CONFIG)
fi

#  ----------------------------- Build And Install -----------------------------

mkdir -p "$PREFIX"

# Temporarily change IFS to space for configure argument expansion
old_ifs="$IFS"
IFS=' '
run "cd '$SRC_DIR' && ./configure ${conf_flags[*]}"
IFS="$old_ifs"

if [[ "$JOBS" == "auto" ]]; then
  if command -v nproc >/dev/null 2>&1; then JOBS=$(nproc); else JOBS=4; fi
fi
run "cd '$SRC_DIR' && make -j$JOBS"

# Build documentation (info files)
say "...building info files"
(
  cd "$SRC_DIR"
  run "make info"
)

run "cd '$SRC_DIR' && make install"
run "cd '$SRC_DIR' && make install-info"

#  --------------------------------- Symlinks --------------------------------

run "ln -sfn '$PREFIX' '$PREFIX_BASE/emacs-current'"

# Remove old symlinks first, then create new ones
for exe in emacs emacsclient; do
	target="$PREFIX/bin/$exe"
	link="$HOME/.local/bin/$exe"
	if [[ -x "$target" ]]; then
		run "rm -f '$link'"
		run "ln -s '$target' '$link'"
	fi
done

#  ---------------------------------- Wrap Up ----------------------------------

command -v emacs >/dev/null && emacs --version | head -n1 || true
command -v emacsclient >/dev/null && emacsclient --version | head -n1 || true

#  ----------------------------- Show Build Features ----------------------------

say "Launching Emacs to display version and build features..."
"$HOME/.local/bin/emacs" -Q --batch --eval '
(progn
  (princ (format "Emacs version: %s\n" emacs-version))
  (princ (format "Build configuration:\n"))
  (princ (format "  Native compilation: %s\n"
				 (if (and (fboundp (quote native-comp-available-p))
						  (native-comp-available-p))
					 "yes" "no")))
  (princ (format "  PGTK: %s\n" (if (featurep (quote pgtk)) "yes" "no")))
  (princ (format "  Tree-sitter: %s\n"
				 (if (fboundp (quote treesit-available-p)) "yes" "no")))
  (princ (format "  JSON: %s\n" (if (fboundp (quote json-parse-string)) "yes" "no")))
  (princ (format "  ImageMagick: %s\n" (if (image-type-available-p (quote imagemagick)) "yes" "no")))
  (princ (format "  Cairo: %s\n" (if (featurep (quote cairo)) "yes" "no")))
  (princ (format "\nFull system configuration:\n%s\n" system-configuration))
  (princ (format "\nConfigured features:\n%s\n" system-configuration-features)))
' 2>&1 | tee -a "$LOGFILE"

echo "Done. See $LOGFILE"