#!/usr/bin/env bash
#
# OpenAgents Control — Architect Fork · web UI service installer
# ============================================================================
# Creates (or removes) a systemd service that runs the OpenCode web UI as a
# background process:
#
#     opencode serve --hostname <host> --port <port>
#
# Run it on its own, or let install.sh call it after OpenCode is installed.
#
# Usage:
#   ./install-service.sh                       # interactive
#   ./install-service.sh --port 4096           # interactive, prefilled port
#   ./install-service.sh --host 0.0.0.0 --port 8080
#   ./install-service.sh --yes                 # non-interactive defaults
#   ./install-service.sh --uninstall           # stop and remove the service
#   ./install-service.sh --dry-run             # show the unit, change nothing
#
# Environment:
#   OPENCODE_SERVICE_NAME   unit name (default: opencode.service)
#   OAC_FORCE_SYSTEMD       1/0 to force systemd detection (containers/CI)
# ============================================================================

set -euo pipefail

SERVICE_NAME="${OPENCODE_SERVICE_NAME:-opencode.service}"
DEFAULT_HOST="127.0.0.1"
DEFAULT_PORT="4096"
OPENCODE_BIN_DIR="${HOME}/.opencode/bin"

# ---------------------------------------------------------------------------
# Output helpers
# ---------------------------------------------------------------------------
if [ -t 1 ]; then
    RED='\033[0;31m'; GREEN='\033[0;32m'; YELLOW='\033[1;33m'
    BLUE='\033[0;34m'; CYAN='\033[0;36m'; MAGENTA='\033[0;35m'
    BOLD='\033[1m'; NC='\033[0m'
else
    RED=''; GREEN=''; YELLOW=''; BLUE=''; CYAN=''; MAGENTA=''; BOLD=''; NC=''
fi
info()    { printf "${BLUE}ℹ${NC} %s\n" "$1"; }
success() { printf "${GREEN}✓${NC} %s\n" "$1"; }
warn()    { printf "${YELLOW}⚠${NC} %s\n" "$1"; }
error()   { printf "${RED}✗${NC} %s\n" "$1" >&2; }
step()    { printf "\n${MAGENTA}${BOLD}▶${NC} %s\n\n" "$1"; }
die()     { error "$1"; exit 1; }

# Prompt on the controlling terminal — works even under `curl … | bash`.
have_tty() {
    [ -t 1 ] || return 1
    [ -t 0 ] && return 0
    [ -r /dev/tty ]
}
tty_read() {
    local __var="$1" __val=""
    if [ -t 0 ] || [ ! -r /dev/tty ]; then
        read -r __val || true
    else
        read -r __val </dev/tty || true
    fi
    printf -v "$__var" '%s' "$__val"
}

have_opencode() {
    command -v opencode >/dev/null 2>&1 && return 0
    [ -x "${OPENCODE_BIN_DIR}/opencode" ] && return 0
    return 1
}
opencode_path() {
    if command -v opencode >/dev/null 2>&1; then command -v opencode
    else printf '%s' "${OPENCODE_BIN_DIR}/opencode"; fi
}

is_systemd() {
    if [ "${OAC_FORCE_SYSTEMD:-}" = "1" ]; then return 0; fi
    if [ "${OAC_FORCE_SYSTEMD:-}" = "0" ]; then return 1; fi
    command -v systemctl >/dev/null 2>&1 && [ -d /run/systemd/system ]
}

# ---------------------------------------------------------------------------
# Arguments
# ---------------------------------------------------------------------------
HOST=""; PORT=""; WORKDIR=""; SVC_USER=""; SVC_GROUP=""
ENABLE=""          # 1 | 0 | empty=ask
ASSUME_YES=0
DRY_RUN=0
UNINSTALL=0

usage() {
    sed -n '2,25p' "$0" | sed 's/^# \{0,1\}//'
}

while [ $# -gt 0 ]; do
    case "$1" in
        --host)        [ $# -ge 2 ] || die "--host needs a value"; HOST="$2"; shift ;;
        --host=*)      HOST="${1#*=}" ;;
        --port)        [ $# -ge 2 ] || die "--port needs a value"; PORT="$2"; shift ;;
        --port=*)      PORT="${1#*=}" ;;
        --dir)         [ $# -ge 2 ] || die "--dir needs a value"; WORKDIR="$2"; shift ;;
        --dir=*)       WORKDIR="${1#*=}" ;;
        --user)        [ $# -ge 2 ] || die "--user needs a value"; SVC_USER="$2"; shift ;;
        --user=*)      SVC_USER="${1#*=}" ;;
        --enable)      ENABLE=1 ;;
        --no-enable)   ENABLE=0 ;;
        -y|--yes)      ASSUME_YES=1 ;;
        --uninstall)   UNINSTALL=1 ;;
        --dry-run)     DRY_RUN=1 ;;
        -h|--help)     usage; exit 0 ;;
        *)             error "Unknown option: $1"; echo; usage; exit 1 ;;
    esac
    shift
done

# ---------------------------------------------------------------------------
# Privilege
# ---------------------------------------------------------------------------
SUDO=""
[ "$(id -u)" != "0" ] && SUDO="sudo"
UNIT_PATH="/etc/systemd/system/${SERVICE_NAME}"

# ---------------------------------------------------------------------------
# Uninstall
# ---------------------------------------------------------------------------
if [ "$UNINSTALL" = 1 ]; then
    if ! is_systemd; then
        warn "systemd not detected — nothing to uninstall here."; exit 0
    fi
    if [ "$DRY_RUN" = 1 ]; then
        info "[dry-run] would stop, disable and delete ${UNIT_PATH}"; exit 0
    fi
    $SUDO systemctl disable --now "$SERVICE_NAME" 2>/dev/null || true
    if [ -e "$UNIT_PATH" ]; then
        $SUDO rm -f "$UNIT_PATH" && success "Removed ${UNIT_PATH}"
    else
        info "No unit at ${UNIT_PATH}"
    fi
    $SUDO systemctl daemon-reload 2>/dev/null || true
    exit 0
fi

# ---------------------------------------------------------------------------
# Locate OpenCode
# ---------------------------------------------------------------------------
have_opencode || die "OpenCode is not installed (looked on PATH and ${OPENCODE_BIN_DIR}). Install it first."
OC_BIN="$(opencode_path)"

# ---------------------------------------------------------------------------
# Prompt (interactive only)
# ---------------------------------------------------------------------------
INTERACTIVE=0
if [ "$ASSUME_YES" = 0 ] && have_tty; then INTERACTIVE=1; fi

if [ "$INTERACTIVE" = 1 ] && [ "$DRY_RUN" = 0 ]; then
    printf "\n${BOLD}Set up the OpenCode web UI as a systemd service?${NC} [Y/n]: "
    ans=""; tty_read ans
    case "$ans" in
        [Nn]*) info "Cancelled."; exit 0 ;;
    esac
fi

[ -n "$HOST" ] || HOST="$DEFAULT_HOST"
[ -n "$PORT" ] || PORT="$DEFAULT_PORT"
[ -n "$WORKDIR" ] || WORKDIR="$(pwd)"
[ -n "$SVC_USER" ] || SVC_USER="$(id -un)"
[ -n "$SVC_GROUP" ] || SVC_GROUP="$(id -gn)"

if [ "$INTERACTIVE" = 1 ] && [ "$DRY_RUN" = 0 ]; then
    v=""
    printf "  Bind address [%s]: " "$HOST"; tty_read v; [ -n "$v" ] && HOST="$v"
    printf "  Port [%s]: " "$PORT"; tty_read v; [ -n "$v" ] && PORT="$v"
    printf "  Working directory [%s]: " "$WORKDIR"; tty_read v; [ -n "$v" ] && WORKDIR="$v"
    printf "  Start now and enable on boot? [Y/n]: "; v=""; tty_read v
    case "$v" in [Nn]*) ENABLE=0 ;; *) ENABLE=1 ;; esac
fi
[ -n "$ENABLE" ] || ENABLE=1

# ---------------------------------------------------------------------------
# Build the unit
# ---------------------------------------------------------------------------
UNIT="$(mktemp 2>/dev/null || mktemp -t oac-unit)"
cat > "$UNIT" <<EOF
[Unit]
Description=opencode server (web UI)
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
User=${SVC_USER}
Group=${SVC_GROUP}
WorkingDirectory=${WORKDIR}
ExecStart=${OC_BIN} serve --hostname ${HOST} --port ${PORT}
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

cleanup() { rm -f "$UNIT"; }
trap cleanup EXIT INT TERM

# ---------------------------------------------------------------------------
# Install
# ---------------------------------------------------------------------------
if ! is_systemd; then
    warn "systemd not detected — cannot install a service here."
    info "Start the web UI manually:  ${OC_BIN} serve --hostname ${HOST} --port ${PORT}"
    exit 0
fi

echo
info "Unit to install:"
echo "------------------------------------------------------------"
cat "$UNIT"
echo "------------------------------------------------------------"

if [ "$DRY_RUN" = 1 ]; then
    warn "Dry run — nothing was written."
    exit 0
fi

if [ "$INTERACTIVE" = 1 ]; then
    printf "Install to %s? [y/N]: " "$UNIT_PATH"
    ans=""; tty_read ans
    case "$ans" in
        [Yy]*) ;;
        *) info "Cancelled."; exit 0 ;;
    esac
fi

# Back up an existing unit before replacing it
if [ -e "$UNIT_PATH" ]; then
    backup="${UNIT_PATH}.bak.$(date +%Y%m%d-%H%M%S)"
    if $SUDO cp "$UNIT_PATH" "$backup" 2>/dev/null; then
        info "Backed up the existing unit to ${backup}"
    fi
fi

if ! $SUDO cp "$UNIT" "$UNIT_PATH"; then
    die "Could not write ${UNIT_PATH} (needs root). Re-run with sudo."
fi
$SUDO systemctl daemon-reload 2>/dev/null || true

if [ "$ENABLE" = 1 ]; then
    if $SUDO systemctl enable --now "$SERVICE_NAME" 2>/dev/null; then
        success "Web UI service enabled — http://${HOST}:${PORT}"
    else
        warn "Unit installed; enable it later:  sudo systemctl enable --now ${SERVICE_NAME}"
    fi
else
    success "Unit installed — start it with:  sudo systemctl start ${SERVICE_NAME}"
fi