#!/bin/sh
# ensure-locale.sh
# Ensures a UTF-8 locale is available and active.
# Works safely on hosts and pure/minimal Docker containers (Alpine, Debian, Ubuntu, RHEL).

ensure_utf8_locale() {
    # 1. Prefer C.UTF-8 if available (standard in modern containers, avoids generation overhead)
    if command -v locale >/dev/null 2>&1 && locale -a 2>/dev/null | grep -qi '^C\.utf'; then
        export LANG=C.UTF-8
        export LC_ALL=C.UTF-8
        return 0
    fi

    # 2. Check if current active charmap is ALREADY UTF-8
    if command -v locale >/dev/null 2>&1; then
        if[ "$(locale charmap 2>/dev/null)" = "UTF-8" ]; then
            # Already UTF-8; ensure variables are cleanly exported for child processes
            export LANG="${LANG:-C.UTF-8}"
            export LC_ALL="${LC_ALL:-$LANG}"
            return 0
        fi
    fi

    # 3. Check for an existing en_US.UTF-8
    if command -v locale >/dev/null 2>&1 && locale -a 2>/dev/null | grep -qi '^en_US\.utf'; then
        export LANG=en_US.UTF-8
        export LC_ALL=en_US.UTF-8
        return 0
    fi

    # 4. Try to generate en_US.UTF-8 (Debian/Ubuntu/Arch)
    if command -v locale-gen >/dev/null 2>&1; then
        echo "[ensure-locale] Generating en_US.UTF-8 locale..." >&2

        # Debian requires uncommenting the locale in /etc/locale.gen first
        if[ -w /etc/locale.gen ]; then
            sed -i 's/^# *\(en_US.UTF-8 UTF-8\)/\1/' /etc/locale.gen 2>/dev/null || true
        fi

        locale-gen en_US.UTF-8 >/dev/null 2>&1 || true

        if locale -a 2>/dev/null | grep -qi '^en_US\.utf'; then
            export LANG=en_US.UTF-8
            export LC_ALL=en_US.UTF-8
            
            # Update system defaults if possible
            if command -v update-locale >/dev/null 2>&1; then
                update-locale LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8 2>/dev/null || true
            fi
            return 0
        fi
    fi

    # 5. Fallback for pure Alpine / minimal musl containers without 'locale' installed
    export LANG=C.UTF-8
    export LC_ALL=C.UTF-8
}

# Run the function
ensure_utf8_locale

# Persist the environment variables for future shell sessions (if running as root)
if[ "$(id -u 2>/dev/null || echo 1)" = "0" ]; then
    if [ -d /etc/profile.d ] &&[ -w /etc/profile.d ]; then
        echo "export LANG=\"$LANG\"" > /etc/profile.d/00-locale.sh
        echo "export LC_ALL=\"$LC_ALL\"" >> /etc/profile.d/00-locale.sh
    fi
fi

# Allow script to be used as a Docker ENTRYPOINT wrapper
# e.g., ./ensure-locale.sh python app.py
if[ $# -gt 0 ]; then
    exec "$@"
fi