#!/usr/bin/env bash
# Create a disposable Linux environment to validate the installer from a
# genuinely clean slate — one that can be thrown away without touching the
# environment you actually work in.
#
# This is the ONLY host-aware file in the tree. Everything else needs just a
# Linux with Docker, which is what keeps other host types a later addition
# rather than a rewrite.
#
# On WSL it creates a second distro. There is no .bat and no PowerShell script:
# wsl.exe is callable from inside WSL, and wslpath converts the paths it wants.
# A machine with no WSL at all needs `wsl --install` run once by hand first —
# scripting a reboot-requiring Windows feature install is not worth it.
#
# Docker: borrowed by default, never installed twice
# --------------------------------------------------
# WSL2 distros share one kernel and one network stack, so two dockerd instances
# contend over docker0 and iptables and can disturb the daemon you depend on.
# (That is why Docker Desktop runs one daemon in a dedicated distro and shares
# its socket rather than installing one per distro.)
#
#   REUSE_DOCKER=1  (default)  borrow the host distro's daemon over /mnt/wsl.
#                              Nothing is installed; nothing can conflict.
#                              Requires `ctrl/dockerhost.sh share` once on the
#                              distro that owns Docker.
#   REUSE_DOCKER=0             install a second daemon in the new distro. Only
#                              if you specifically want to test a from-scratch
#                              Docker install, and not on a machine you need.
#
# Borrowing is also the more honest test: rig never installs Docker anyway — it
# is the documented prerequisite — so a clean box does not need its own to
# exercise everything rig actually does.
#
# Usage: newbox.sh create | destroy [--purge] | status | shell
set -euo pipefail
cd "$(dirname "$0")"

source ./lib/config.sh
load_config

REPO="$(cd .. && pwd)"

# The distro is named after this environment, and that derived name is the ONLY
# thing this script will ever destroy. See guard_name().
BOX="${BOX:-${CLUSTER}box}"
BOX_USER="${BOX_USER:-dev}"

# Borrow the host distro's Docker rather than installing a second daemon.
REUSE_DOCKER="${REUSE_DOCKER:-1}"
SHARED_SOCK=/mnt/wsl/shared-docker/docker.sock

WSL_EXE=/mnt/c/Windows/System32/wsl.exe

# ── host detection ─────────────────────────────────────────────────────────

require_wsl() {
    if ! grep -qi microsoft /proc/version 2>/dev/null; then
        cat >&2 <<'EOF'
newbox is WSL-only for now.

If WSL is not installed, run `wsl --install` from an elevated Windows prompt
first — see "Starting from plain Windows" in README.md.

On native Linux you do not need it: rig already isolates environments by
directory (own cluster, context, images and port block), so a second copy in a
second directory is the clean slate. To validate the installer itself against a
bare system, run ctrl/deps.sh against a stock Debian container instead.
EOF
        exit 1
    fi
    if [ ! -x "$WSL_EXE" ]; then
        echo "wsl.exe not found at $WSL_EXE" >&2
        exit 1
    fi
}

wsl_list() { "$WSL_EXE" -l -q 2>/dev/null | tr -d '\0\r'; }
box_exists() { wsl_list | grep -qx "$BOX"; }

# `wsl --unregister` permanently deletes a distro's filesystem. The whole safety
# story is this function: only the name derived from this directory can ever be
# a target, so a typo or a stray argument cannot destroy the distro you work in.
guard_name() {
    local derived="${CLUSTER}box"
    if [ "$BOX" != "$derived" ]; then
        echo "refusing: BOX='$BOX' is not the name derived from this directory ('$derived')." >&2
        echo "That guard exists because --unregister is irreversible." >&2
        exit 1
    fi
    if [ -z "$CLUSTER" ] || [ "$BOX" = "box" ]; then
        echo "refusing: empty environment name" >&2
        exit 1
    fi
}

# ── create ─────────────────────────────────────────────────────────────────

rootfs_path() {
    local win_home; win_home=$(wslpath "$("$WSL_EXE" -d "$(wsl_list | head -1)" -e printf '%s' "$USERPROFILE" 2>/dev/null || true)" 2>/dev/null || true)
    # Simpler and reliable: use the current user's Windows home via /mnt/c.
    ls -d /mnt/c/Users/*/ 2>/dev/null | grep -viE '/(All Users|Default|Default User|Public)/$' | head -1
}

build_rootfs() {
    local tar="$1"
    if [ -f "$tar" ]; then
        echo "  rootfs cached: $(basename "$tar")"
        return
    fi
    echo "  exporting a stock Debian rootfs (cached for next time)"
    local cid; cid=$(docker create debian:trixie-slim)
    docker export "$cid" > "$tar"
    docker rm -f "$cid" >/dev/null
}

provision() {
    echo "  provisioning (root)"
    local hosts_block
    hosts_block=$(CLUSTER="$CLUSTER" HTTP_PORT="$HTTP_PORT" \
                  envsubst < ./hosts.tmpl 2>/dev/null || sed "s/\${CLUSTER}/$CLUSTER/g" ./hosts.tmpl)

    # Piped as stdin rather than a second script file, the same shape as any
    # remote provisioning heredoc. Everything here is idempotent so a failed run
    # can simply be repeated.
    "$WSL_EXE" -d "$BOX" -u root -- bash -s <<PROVISION
set -euo pipefail

export DEBIAN_FRONTEND=noninteractive
apt-get update -qq
apt-get install -y -qq ca-certificates curl gnupg sudo >/dev/null

if [ "$REUSE_DOCKER" = "1" ]; then
    # Borrow the host distro's daemon: CLI only, no dockerd, nothing to
    # conflict with. The GID must match the owner's or the shared socket is
    # unreadable here even though it is visible.
    install -m 0755 -d /etc/apt/keyrings
    if [ ! -f /etc/apt/keyrings/docker.asc ]; then
        curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc
        chmod a+r /etc/apt/keyrings/docker.asc
    fi
    echo "deb [arch=\$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian \$(. /etc/os-release && echo \$VERSION_CODENAME) stable" \
        > /etc/apt/sources.list.d/docker.list
    apt-get update -qq
    apt-get install -y -qq docker-ce-cli >/dev/null

    echo "export DOCKER_HOST=unix://$SHARED_SOCK" > /etc/profile.d/rig-docker-host.sh

    if [ -f /mnt/wsl/shared-docker/OWNER ]; then
        gid=\$(awk '/docker gid:/ {print \$3}' /mnt/wsl/shared-docker/OWNER)
        if [ -n "\$gid" ]; then
            getent group docker >/dev/null && groupmod -g "\$gid" docker || groupadd -g "\$gid" docker
        fi
    fi
else
    # A second daemon. Only when deliberately testing a from-scratch install.
    install -m 0755 -d /etc/apt/keyrings
    if [ ! -f /etc/apt/keyrings/docker.asc ]; then
        curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc
        chmod a+r /etc/apt/keyrings/docker.asc
    fi
    echo "deb [arch=\$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian \$(. /etc/os-release && echo \$VERSION_CODENAME) stable" \
        > /etc/apt/sources.list.d/docker.list
    apt-get update -qq
    apt-get install -y -qq docker-ce docker-ce-cli containerd.io >/dev/null
fi

id -u "$BOX_USER" >/dev/null 2>&1 || useradd -m -s /bin/bash "$BOX_USER"
usermod -aG sudo,docker "$BOX_USER"
echo "$BOX_USER ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/90-$BOX_USER
chmod 0440 /etc/sudoers.d/90-$BOX_USER

# systemd is off by default in WSL, and Docker needs it. Takes effect on the
# next start of this distro, which is why create() terminates it below.
cat > /etc/wsl.conf <<WSLCONF
[boot]
systemd=true

[user]
default=$BOX_USER
WSLCONF

# The default inotify limits are low enough that file watching silently stops
# working — no error, changes just stop being noticed. Fix it before it bites.
cat > /etc/sysctl.d/99-rig.conf <<SYSCTL
fs.inotify.max_user_watches=524288
fs.inotify.max_user_instances=512
SYSCTL

if ! grep -q 'rig environment' /etc/hosts 2>/dev/null; then
    { echo ""; echo "# rig environment"; cat <<'HOSTS'
$hosts_block
HOSTS
    } >> /etc/hosts
fi

touch /etc/rig-provisioned
PROVISION
}

create() {
    require_wsl
    guard_name

    local winhome; winhome=$(rootfs_path)
    [ -n "$winhome" ] || { echo "could not locate the Windows user directory" >&2; exit 1; }
    local tar="${winhome}rig-rootfs.tar"
    local installdir="${winhome}WSL/${BOX}"

    echo "creating '$BOX'"
    if [ "$REUSE_DOCKER" = "1" ]; then
        echo "  docker: borrowing the host distro's daemon (nothing installed)"
        if [ ! -S "$SHARED_SOCK" ]; then
            echo
            echo "  No shared socket yet. In the distro that owns Docker, run once:"
            echo "      sudo bash ctrl/dockerhost.sh share"
            echo "  That adds one systemd drop-in and nothing else; undo with 'unshare'."
            echo "  Continuing — the box will be created, but Docker won't work in it"
            echo "  until you do that."
        fi
    else
        echo
        echo "  REUSE_DOCKER=0: installing a SECOND Docker daemon."
        echo "  WSL distros share a network stack, so this can disturb Docker in"
        echo "  the distro you work in. Ctrl-C now if that is a bad trade today."
        echo
        sleep 4
    fi
    echo

    if box_exists; then
        echo "  distro already registered"
    else
        build_rootfs "$tar"
        mkdir -p "$installdir"
        "$WSL_EXE" --import "$BOX" "$(wslpath -w "$installdir")" "$(wslpath -w "$tar")" --version 2
    fi

    # Resumable: a partially-created box is finished rather than restarted.
    if "$WSL_EXE" -d "$BOX" -u root -- test -f /etc/rig-provisioned 2>/dev/null; then
        echo "  already provisioned"
    else
        provision
        echo "  restarting the distro so systemd and group membership apply"
        "$WSL_EXE" --terminate "$BOX"      # ONLY this distro; never --shutdown
    fi

    echo "  copying rig in"
    tar c -C "$REPO" --exclude=def --exclude=.git --exclude=ctrl/.env . \
        | "$WSL_EXE" -d "$BOX" -u "$BOX_USER" -- bash -lc "mkdir -p ~/rig && tar x -C ~/rig"

    echo
    echo "  docker: $("$WSL_EXE" -d "$BOX" -u "$BOX_USER" -- bash -lc 'systemctl is-active docker 2>/dev/null || echo inactive')"
    echo
    echo "next:"
    echo "  make newbox shell        # a shell inside it"
    echo "  then: cd ~/rig && make check && make deps && make cluster up"
    echo
    echo "For a browser on Windows to resolve the hostnames, paste this into"
    echo "C:\\Windows\\System32\\drivers\\etc\\hosts (it has no wildcard support):"
    CLUSTER="$CLUSTER" envsubst < ./hosts.tmpl 2>/dev/null | grep -v '^#' | grep -v '^$' | sed 's/^/    /'
}

# ── the rest ───────────────────────────────────────────────────────────────

destroy() {
    require_wsl
    guard_name

    if ! box_exists; then
        echo "no distro '$BOX' to remove"
    else
        echo "about to PERMANENTLY delete the distro '$BOX' and its filesystem."
        "$WSL_EXE" --terminate "$BOX" 2>/dev/null || true
        "$WSL_EXE" --unregister "$BOX"
        echo "  unregistered"
    fi

    local winhome; winhome=$(rootfs_path)
    rm -rf "${winhome}WSL/${BOX}" 2>/dev/null || true

    if [ "${1:-}" = "--purge" ]; then
        rm -f "${winhome}rig-rootfs.tar"
        echo "  cached rootfs removed"
    fi
}

status() {
    require_wsl
    echo "environment  $CLUSTER"
    echo "distro       $BOX"
    if box_exists; then
        echo "registered   yes"
        echo "provisioned  $("$WSL_EXE" -d "$BOX" -u root -- test -f /etc/rig-provisioned 2>/dev/null && echo yes || echo no)"
        echo "docker       $("$WSL_EXE" -d "$BOX" -u root -- bash -lc 'systemctl is-active docker 2>/dev/null' || echo unknown)"
        echo "rig copied   $("$WSL_EXE" -d "$BOX" -u "$BOX_USER" -- bash -lc 'test -f ~/rig/Makefile && echo yes || echo no' 2>/dev/null)"
    else
        echo "registered   no"
    fi
    echo
    echo "all distros (this one is never touched unless it is '$BOX'):"
    wsl_list | sed 's/^/  /'
}

shell() {
    require_wsl
    box_exists || { echo "no distro '$BOX' — run 'make newbox' first" >&2; exit 1; }
    "$WSL_EXE" -d "$BOX" -u "$BOX_USER" --cd '~'
}

case "${1:-status}" in
    create)  create ;;
    destroy) shift; destroy "${1:-}" ;;
    status)  status ;;
    shell)   shell ;;
    *)       echo "usage: $0 [create|destroy [--purge]|status|shell]" >&2; exit 1 ;;
esac