#!/bin/sh
# bootstrap/python
#
# Python-finding script for all `sh` environments, including Linux, MSYS2,
# Git for Windows, and GitHub Desktop. Invokable from CLI or automation.
#
# If a python.exe installed by `python_.ps1` is present, it will be used.
# Otherwise, this script requires a system `python3` and `pip` to be provided,
# and will create a standard virtualenv in which to install `requirements.txt`.
set -e

# Convenience variables
Bootstrap="$(dirname "$0")"
Sdk="$(dirname "$Bootstrap")"
Cache="$Bootstrap/.cache"
if [ "$TG_BOOTSTRAP_CACHE" ]; then
	Cache="$TG_BOOTSTRAP_CACHE"
fi
OldPWD="$PWD"
cd "$Bootstrap/../.."
. ./dependencies.sh  # sets PYTHON_VERSION
cd "$OldPWD"
PythonVersion="$PYTHON_VERSION"
PythonDir="$Cache/python-$PythonVersion"
PythonExe="$PythonDir/python.exe"
Log="$Cache/last-command.log"

# If a portable Python for Windows is not present, search on $PATH.
if [ "$(uname)" = "Linux" ] || [ ! -f "$PythonExe" ]; then
	# Strip the "App Execution Aliases" from $PATH. Even if the user installed
	# Python using the Windows Store on purpose, these aliases always generate
	# "Permission denied" errors when sh.exe tries to invoke them.
	PATH=$(echo "$PATH" | tr ":" "\n" | grep -v "AppData/Local/Microsoft/WindowsApps" | tr "\n" ":")

	# Try to find a Python executable.
	if command -v python3 >/dev/null 2>&1; then
		PythonExe=python3
	elif command -v python >/dev/null 2>&1; then
		PythonExe=python
	elif command -v py >/dev/null 2>&1; then
		PythonExe="py -3"
	else
		echo
		if command -v apt-get >/dev/null 2>&1; then
			echo "Please install Python using your system's package manager:"
			echo "    sudo apt-get install python3 python3-pip"
		elif [ "$(uname -o)" = "Msys" ]; then
			echo "Please run tools/bootstrap/python.bat instead of tools/bootstrap/python once to"
			echo "install Python automatically, or install it from https://www.python.org/downloads/"
			# TODO: give MSYS pacman advice?
		elif command -v pacman >/dev/null 2>&1; then
			echo "Please install Python using your system's package manager:"
			echo "    sudo pacman -S python python-pip"
		else
			echo "Please install Python from https://www.python.org/downloads/ or using your system's package manager."
		fi
		echo
		exit 1
	fi

	# Create a venv and activate it
	PythonDir="$Cache/venv"
	if [ ! -d "$PythonDir" ]; then
		echo "Creating virtualenv..."
		"$PythonExe" -m venv "$PythonDir"
	fi
	if [ -f "$PythonDir/bin/python" ]; then
		PythonExe="$PythonDir/bin/python"
	elif [ -f "$PythonDir/scripts/python3.exe" ]; then
		PythonExe="$PythonDir/scripts/python3.exe";
	else
		echo "bootstrap/python failed to find the python executable inside its virtualenv"
		exit 1
	fi
fi

# Use pip to install our requirements
if [ ! -f "$PythonDir/requirements.txt" ] || [ "$(b2sum < "$Sdk/requirements.txt")" != "$(b2sum < "$PythonDir/requirements.txt")" ]; then
	echo "Updating dependencies..."
	"$PythonExe" -m pip install -U wheel
	"$PythonExe" -m pip install -U pip -r "$Sdk/requirements.txt"
	cp "$Sdk/requirements.txt" "$PythonDir/requirements.txt"
	echo "---"
fi

# Verify version and deduce the path separator
PythonMajor=${PythonVersion%%.*}
PythonMinor=${PythonVersion#*.}
PythonMinor=${PythonMinor%.*}
PATHSEP=$("$PythonExe" - "$PythonMajor" "$PythonMinor" <<'EOF'
import sys, os
if sys.version_info.major != int(sys.argv[1]) or sys.version_info.minor < int(sys.argv[2]):
	print("Error: Python ", sys.argv[1], ".", sys.argv[2], " or later is required, but you have:\n", sys.version, sep="", file=sys.stderr)
	exit(1)
print(os.pathsep)
EOF
)

# Cheap shell function if tee.exe is not available
if ! command -v tee >/dev/null 2>&1; then
	tee() {
		# Fudge: assume $1 is always "-a"
		while read -r line; do
			echo "$line" >> "$2"
			echo "$line"
		done
	}
fi

# Invoke python with all command-line arguments
export PYTHONPATH="$Sdk$PATHSEP${PYTHONPATH:-}"
mkdir -p "$Cache"
printf '%s\n' "$PythonExe" "$@" > "$Log"
printf -- '---\n' >> "$Log"
exec 4>&1
exitstatus=$({ { set +e; "$PythonExe" -u "$@" 2>&1 3>&-; printf %s $? >&3; } 4>&- | tee -a "$Log" 1>&4; } 3>&1)
exec 4>&-
exit "$exitstatus"