# ╔══════════════════════════════════════════════════════════════════╗
# ║  arch-dev roaming :: engine                                     ║
# ║  Roaming ~ over the tailnet. Source this from .zshrc.           ║
# ║                                                                  ║
# ║  Reads ~/.config/roaming/hosts and generates a function per     ║
# ║  host so you can run:                                            ║
# ║    mail                      → interactive shell on mail         ║
# ║    mail tail -f /var/log/x   → run with TTY (works for -f, sudo) ║
# ║    mount_host mail           → sshfs the host's mount at         ║
# ║                                /workspace/mail                   ║
# ╚══════════════════════════════════════════════════════════════════╝

export ROAMING_DIR="${ROAMING_DIR:-$HOME/.config/roaming}"
export ROAMING_HOSTS="${ROAMING_HOSTS:-$ROAMING_DIR/hosts}"
export ROAMING_MOUNT_BASE="${ROAMING_MOUNT_BASE:-/workspace}"
export ROAMING_DEFAULT_USER="${ROAMING_DEFAULT_USER:-$USER}"

# sshfs options that prevent the dreaded indefinite-freeze on network blips.
# ServerAliveInterval=15 + CountMax=3 → I/O errors out after ~45s instead of
# hanging forever. reconnect re-establishes when the host comes back.
export ROAMING_SSHFS_OPTS="reconnect,ServerAliveInterval=15,ServerAliveCountMax=3,follow_symlinks"

# ── Internal: resolve a host name to its registry fields ──────────────────────
# Sets globals: _RH_NAME _RH_FQDN _RH_USER _RH_MOUNT
# Returns 1 if not found.
_roaming_lookup() {
    local want="$1"
    [[ -f "$ROAMING_HOSTS" ]] || return 1
    local name fqdn user mount
    while read -r name fqdn user mount; do
        [[ -z "$name" || "$name" == \#* ]] && continue
        if [[ "$name" == "$want" ]]; then
            _RH_NAME="$name"
            _RH_FQDN="$fqdn"
            _RH_USER="${user:-$ROAMING_DEFAULT_USER}"
            _RH_MOUNT="$mount"
            return 0
        fi
    done < "$ROAMING_HOSTS"
    return 1
}

# ── Internal: the actual remote-exec logic ────────────────────────────────────
# No args → interactive shell. Args → run with a TTY (so tail -f / sudo work).
# "Dumb" by design: pipes/redirects run LOCALLY, exactly like plain ssh.
_roaming_exec() {
    local name="$1"; shift
    if ! _roaming_lookup "$name"; then
        echo "roaming: unknown host '$name' (check $ROAMING_HOSTS)" >&2
        return 1
    fi
    local target="${_RH_USER}@${_RH_FQDN}"
    if [[ $# -eq 0 ]]; then
        ssh -t "$target"
    else
        ssh -t "$target" "$@"
    fi
}

# ── mount_host <name> ─────────────────────────────────────────────────────────
mount_host() {
    local name="$1"
    if [[ -z "$name" ]]; then
        echo "usage: mount_host <name>" >&2
        return 1
    fi
    if ! _roaming_lookup "$name"; then
        echo "roaming: unknown host '$name'" >&2
        return 1
    fi
    if [[ -z "$_RH_MOUNT" ]]; then
        echo "roaming: '$name' has no mount path in registry" >&2
        return 1
    fi
    local mp="$ROAMING_MOUNT_BASE/$name"
    # Already mounted?
    if mountpoint -q "$mp" 2>/dev/null; then
        echo "roaming: $name already mounted at $mp"
        return 0
    fi
    mkdir -p "$mp"
    echo "roaming: mounting ${_RH_USER}@${_RH_FQDN}:${_RH_MOUNT} → $mp"
    sshfs "${_RH_USER}@${_RH_FQDN}:${_RH_MOUNT}" "$mp" \
        -o "$ROAMING_SSHFS_OPTS" \
        && echo "roaming: ✓ mounted" \
        || echo "roaming: ✗ mount failed" >&2
}

# ── unmount_host <name> ───────────────────────────────────────────────────────
unmount_host() {
    local name="$1"
    if [[ -z "$name" ]]; then
        echo "usage: unmount_host <name>" >&2
        return 1
    fi
    local mp="$ROAMING_MOUNT_BASE/$name"
    if ! mountpoint -q "$mp" 2>/dev/null; then
        echo "roaming: $name not mounted"
        return 0
    fi
    # fusermount3 first; -z (lazy) as fallback for stale mounts
    fusermount3 -u "$mp" 2>/dev/null \
        || fusermount3 -uz "$mp" 2>/dev/null \
        || umount "$mp" 2>/dev/null
    if mountpoint -q "$mp" 2>/dev/null; then
        echo "roaming: ✗ failed to unmount $name (stale? try: fusermount3 -uz $mp)" >&2
        return 1
    fi
    rmdir "$mp" 2>/dev/null
    echo "roaming: ✓ unmounted $name"
}

# ── roaming-status ────────────────────────────────────────────────────────────
roaming-status() {
    echo "── registered hosts ──"
    if [[ -f "$ROAMING_HOSTS" ]]; then
        local name fqdn user mount
        while read -r name fqdn user mount; do
            [[ -z "$name" || "$name" == \#* ]] && continue
            local mp="$ROAMING_MOUNT_BASE/$name"
            local mflag=""
            mountpoint -q "$mp" 2>/dev/null && mflag="  [mounted: $mp]"
            printf "  %-10s %s@%s%s\n" "$name" "${user:-$ROAMING_DEFAULT_USER}" "$fqdn" "$mflag"
        done < "$ROAMING_HOSTS"
    else
        echo "  (no registry at $ROAMING_HOSTS)"
    fi
}

# ── Generate a function per host ──────────────────────────────────────────────
# After this loop, each registry entry `mail` becomes a `mail` command.
_roaming_generate() {
    [[ -f "$ROAMING_HOSTS" ]] || return 0
    local name fqdn user mount
    while read -r name fqdn user mount; do
        [[ -z "$name" || "$name" == \#* ]] && continue
        # Skip if it would clobber an existing command (safety)
        if command -v "$name" >/dev/null 2>&1 && ! typeset -f "$name" >/dev/null 2>&1; then
            echo "roaming: skipping '$name' — conflicts with existing command" >&2
            continue
        fi
        eval "$name() { _roaming_exec '$name' \"\$@\"; }"
    done < "$ROAMING_HOSTS"
}

# Reload registry + regenerate functions (call after editing hosts)
roaming-reload() {
    _roaming_generate
    echo "roaming: reloaded $(grep -cvE '^\s*#|^\s*$' "$ROAMING_HOSTS" 2>/dev/null || echo 0) host(s)"
}

# Generate on source
_roaming_generate