#!/usr/bin/env bash

set -euo pipefail

SCRIPT_PATH="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
DEFAULT_TOOLCHAIN_URL="https://developer.arm.com/-/media/Files/downloads/gnu-rm/9-2019q4/RC2.1/gcc-arm-none-eabi-9-2019-q4-major-x86_64-linux.tar.bz2?revision=6e63531f-8cb1-40b9-bbfc-8a57cdfc01b4&la=en&hash=F761343D43A0587E8AC0925B723C04DBFB848339"

mbt_log() {
    printf "mbt: %s\n" "$*"
}

mbt_error() {
    printf "mbt: error: %s\n" "$*" >&2
}

mbt_die() {
    mbt_error "$*"
    exit 1
}

mbt_command_exists() {
    command -v "$1" >/dev/null 2>&1
}

mbt_default_jobs() {
    local jobs

    jobs="$(getconf _NPROCESSORS_ONLN 2>/dev/null || true)"
    if [[ -z "$jobs" ]] && mbt_command_exists nproc; then
        jobs="$(nproc)"
    fi
    if [[ -z "$jobs" ]]; then
        jobs=1
    fi

    printf "%s" "$jobs"
}

mbt_detect_distro() {
    if mbt_command_exists apt-get; then
        printf "debian"
        return 0
    fi
    if mbt_command_exists pacman; then
        printf "arch"
        return 0
    fi
    printf "unknown"
}

mbt_run_privileged() {
    if [[ "${EUID:-$(id -u)}" -eq 0 ]]; then
        "$@"
        return
    fi

    if ! mbt_command_exists sudo; then
        mbt_die "sudo is required for dependency installation. Re-run as root or install sudo."
    fi

    sudo "$@"
}

mbt_install_deps() {
    local distro
    distro="$(mbt_detect_distro)"

    case "$distro" in
    debian)
        mbt_log "detected Debian-like environment; installing required packages."
        mbt_run_privileged apt-get update
        mbt_run_privileged apt-get install -y --no-install-recommends \
            git tar wget dfu-util cmake make python3 bzip2 lz4 curl hackrf \
            python3-setuptools python3-yaml binutils python3-setuptools ccache ninja-build
        ;;
    arch)
        mbt_log "detected Arch-like environment; installing required packages."
        mbt_run_privileged pacman -Sy --needed --noconfirm \
            git tar wget dfu-util cmake make python3 bzip2 lz4 curl hackrf \
            python-distutils-extra python-setuptools python-pip python-yaml \
            ninja ccache binutils
        ;;
    *)
        mbt_die "unsupported distribution. Install dependencies manually (see wiki on github), or you can send PR to support for your distro. Detected distro: $distro"
        ;;
    esac
}

mbt_sync_submodules() {
    local jobs
    jobs="$(mbt_default_jobs)"
    mbt_log "syncing submodules."
    git -C "$SCRIPT_PATH" submodule update --init --recursive --jobs "$((jobs * 2))"
}

mbt_enable_toolchain_env() {
    export MBT_ROOT="$SCRIPT_PATH"
    export MBT_TOOLCHAIN_DIR="${MBT_TOOLCHAIN_DIR:-$SCRIPT_PATH/armbin}"
    export MBT_TOOLCHAIN_URL="${MBT_TOOLCHAIN_URL:-$DEFAULT_TOOLCHAIN_URL}"
    export MBT_EXPECTED_GCC_VERSION="${MBT_EXPECTED_GCC_VERSION:-9.2.1}"

    if [[ -z "${MBT_FORCE_TOOLCHAIN+x}" ]]; then
        MBT_FORCE_TOOLCHAIN="${FORCE_TOOLCHAIN:-0}"
    fi
    export MBT_FORCE_TOOLCHAIN

    if [[ -z "${MBT_NO_TOOLCHAIN_DOWNLOAD+x}" ]]; then
        MBT_NO_TOOLCHAIN_DOWNLOAD="${NO_TOOLCHAIN_DOWNLOAD:-0}"
    fi
    export MBT_NO_TOOLCHAIN_DOWNLOAD
    export MBT_VERBOSE="${MBT_VERBOSE:-}"

    # shellcheck source=/dev/null
    . "$SCRIPT_PATH/scripts/toolchain/mbtenv.sh"
}

mbt_use_existing_toolchain_env() {
    local repo_toolchain_bin="$SCRIPT_PATH/armbin/bin"

    if [[ ! -d "$repo_toolchain_bin" ]]; then
        return 0
    fi

    case ":$PATH:" in
    *":$repo_toolchain_bin:"*)
        return 0
        ;;
    esac

    export PATH="$repo_toolchain_bin:$PATH"
}

mbt_normalize_device() {
    local raw
    raw="$(printf "%s" "$1" | tr '[:upper:]' '[:lower:]')"

    case "$raw" in
    1|one|hackrf|hackrf-one)
        printf "hackrf-one"
        ;;
    2|pro|hackrf-pro|praline)
        printf "hackrf-pro"
        ;;
    3|portarf|porta-rf|porta_rf)
        printf "portarf"
        ;;
    *)
        return 1
        ;;
    esac
}

mbt_prompt_device() {
    local choice normalized

    cat >&2 <<'EOF'
Select device type:
  1) HackRF One
  2) HackRF Pro (PRALINE)
  3) PortaRF
EOF

    while true; do
        printf "Device [1-3]: " >&2
        if ! IFS= read -r choice; then
            return 1
        fi

        normalized="$(mbt_normalize_device "$choice" 2>/dev/null || true)"
        if [[ -n "$normalized" ]]; then
            printf "%s" "$normalized"
            return 0
        fi
        mbt_error "invalid device selection: $choice"
    done
}

mbt_print_help() {
    cat <<'EOF'
Usage:
  ./mbt                          One-step build flow (installs deps, syncs submodules, downloads toolchain, asks for device, builds)
  ./mbt build [options]          Developer build flow
  ./mbt deps                     Install distro dependencies only
  ./mbt toolchain [--force-toolchain]
                                 Download/setup ARM toolchain only
  ./mbt doctor                   Validate host setup and report gaps
  ./mbt shell [options]          Open a shell with toolchain exported for this session
  ./mbt benchmark [options]      Benchmark clean-build time across generators and ccache modes

Build options:
  -d, --device <name>            Device: hackrf-one | hackrf-pro | portarf
  --ccache / --no-ccache         Toggle USE_CCACHE (default: on)
  --with-deps / --no-deps        Install Linux dependencies before build
  --with-submodule-sync          Update git submodules before build (default)
  --no-submodule-sync            Skip submodule sync
  --with-toolchain               Ensure toolchain exists and matches expected version (default)
  --no-toolchain                 Skip toolchain checks/downloads and use existing PATH (prepends ./armbin/bin if present)
  --force-toolchain              Re-download and reinstall toolchain
  -B, --build-dir <path>         Build directory (default: ./build)
  -G, --generator <name>         CMake generator (default: Ninja)
  -j, --jobs <n>                 Build parallelism (default: host CPU count)
  --target <name>                Build a specific target
  --clean                        Remove build directory, run libopencm3 clean, and exit
  --cmake-arg <arg>              Extra CMake configure arg (repeatable)
  --build-arg <arg>              Extra cmake --build arg (repeatable)
  -y, --non-interactive          Fail instead of prompting when required input is missing
  -h, --help                     Show this help

Benchmark options (in addition to -d/--device, -j/--jobs, --target, -B, --cmake-arg):
  --bench-generators <list>      Comma list of generators to test: ninja,make (default: all installed)
  --bench-ccache <list>          Comma list of ccache modes: off,cold,warm (default: off,cold,warm)
                                   off  = ccache disabled (baseline)
                                   cold = ccache on, empty cache (first-build/populate cost)
                                   warm = ccache on, pre-populated cache (the ccache speedup)
                                 Each cell is a full clean build in a dedicated dir (default: ./build-bench),
                                 using an isolated CCACHE_DIR so your real ccache is never touched.

Examples:
  ./mbt
  ./mbt build --device hackrf-one
  ./mbt build --device hackrf-pro --no-submodule-sync
  ./mbt build --device portarf --no-toolchain --no-deps
  ./mbt build --device hackrf-one --cmake-arg=-DVERSION_STRING=my-build
  ./mbt benchmark --device hackrf-one --no-deps --no-submodule-sync
  ./mbt benchmark --device hackrf-one --bench-generators ninja --bench-ccache off,cold,warm
  ./mbt benchmark --device hackrf-one --bench-generators ninja,make --bench-ccache off
EOF
}

mbt_doctor() {
    local distro missing=0 toolchain_cc toolchain_version cmd
    local -a required_cmds

    distro="$(mbt_detect_distro)"
    mbt_log "doctor report for $SCRIPT_PATH"
    mbt_log "distro family: $distro"

    required_cmds=(git tar wget dfu-util cmake python3 bzip2 lz4 curl ccache ninja)
    if [[ "$distro" == "arch" ]]; then
        required_cmds+=(make)
    fi

    for cmd in "${required_cmds[@]}"; do
        if mbt_command_exists "$cmd"; then
            printf "  [ok] %s\n" "$cmd"
        else
            printf "  [missing] %s\n" "$cmd"
            missing=1
        fi
    done

    toolchain_cc="$SCRIPT_PATH/armbin/bin/arm-none-eabi-gcc"
    if [[ -x "$toolchain_cc" ]]; then
        toolchain_version="$("$toolchain_cc" -dumpfullversion 2>/dev/null || "$toolchain_cc" -dumpversion 2>/dev/null || true)"
        printf "  [ok] arm-none-eabi-gcc %s (%s)\n" "$toolchain_version" "$toolchain_cc"
        if [[ "$toolchain_version" != "9.2.1" ]]; then
            printf "  [warn] expected arm-none-eabi-gcc 9.2.1\n"
        fi
    else
        if mbt_command_exists arm-none-eabi-gcc; then
            toolchain_cc="arm-none-eabi-gcc"
            toolchain_version="$("$toolchain_cc" -dumpfullversion 2>/dev/null || "$toolchain_cc" -dumpversion 2>/dev/null || true)"
            printf "  [ok] arm-none-eabi-gcc %s (%s)\n" "$toolchain_version" "$toolchain_cc"
            if [[ "$toolchain_version" != "9.2.1" ]]; then
                printf "  [warn] expected arm-none-eabi-gcc 9.2.1\n"
            fi
        else
            printf "  [missing] %s\n" "$toolchain_cc"
            missing=1
        fi
    fi

    if git -C "$SCRIPT_PATH" submodule status --recursive | grep -q '^-'; then
        printf "  [warn] some submodules are not initialized (run ./mbt build --with-submodule-sync --device hackrf-one)\n"
    else
        printf "  [ok] submodules initialized\n"
    fi

    if [[ "$missing" -ne 0 ]]; then
        mbt_error "doctor found missing prerequisites."
        return 1
    fi

    mbt_log "doctor passed."
    return 0
}

mbt_validate_jobs() {
    [[ "$1" =~ ^[0-9]+$ ]] && [[ "$1" -gt 0 ]]
}

mbt_detect_cached_device() {
    local build_dir="$1"
    local cache_file="$build_dir/CMakeCache.txt"
    local board flash_limit

    if [[ ! -f "$cache_file" ]]; then
        return 1
    fi

    board="$(grep -E '^BOARD:' "$cache_file" | head -n 1 | cut -d= -f2- || true)"
    flash_limit="$(grep -E '^FLASH_MB_LIMIT_SIZE:' "$cache_file" | head -n 1 | cut -d= -f2- || true)"

    if [[ "$board" == "PRALINE" ]]; then
        printf "hackrf-pro"
        return 0
    fi

    case "$flash_limit" in
    2|2.0)
        printf "portarf"
        return 0
        ;;
    1|1.0)
        printf "hackrf-one"
        return 0
        ;;
    esac

    printf "unknown"
    return 0
}

# libopencm3 builds in-source (inside the submodule tree), so deleting the CMake
# build dir alone does NOT rebuild it. Clean it explicitly for a true clean build.
# Set quiet=1 to suppress make output (used by the benchmark).
mbt_clean_libopencm3() {
    local quiet="${1:-0}"
    local libopencm3_dir="$SCRIPT_PATH/hackrf/firmware/libopencm3"

    if [[ ! -d "$libopencm3_dir" ]]; then
        mbt_error "libopencm3 directory not found: $libopencm3_dir"
        return 1
    fi

    if [[ "$quiet" -eq 1 ]]; then
        make -C "$libopencm3_dir" clean >/dev/null 2>&1
    else
        mbt_log "cleaning libopencm3: $libopencm3_dir"
        make -C "$libopencm3_dir" clean
    fi
}

mbt_clean() {
    local build_dir="$1"

    mbt_log "cleaning build directory: $build_dir"
    if ! rm -rf "$build_dir"; then
        mbt_error "failed to delete build directory. Try running ./mbt --clean as root."
        return 1
    fi

    mbt_clean_libopencm3 0
}

mbt_report_build_error() {
    printf '%s\n' 'Build error happened. Try to fix your code, or run ./mbt --clean and try again' >&2
}

# Print the device-specific CMake args, one per line (empty for hackrf-one).
mbt_device_args() {
    case "$1" in
    hackrf-one)
        : # no extra args
        ;;
    hackrf-pro)
        printf '%s\n' "-DBOARD=PRALINE"
        ;;
    portarf)
        printf '%s\n' "-DFLASH_MB_SIZE=2" "-DFLASH_MB_LIMIT_SIZE=2"
        ;;
    *)
        return 1
        ;;
    esac
}

# Normalize a user-supplied generator name to a canonical CMake generator name.
mbt_resolve_generator() {
    local raw
    raw="$(printf "%s" "$1" | tr '[:upper:]' '[:lower:]')"
    case "$raw" in
    ninja)
        printf "Ninja"
        ;;
    make|makefiles|unixmakefiles|"unix makefiles")
        printf "Unix Makefiles"
        ;;
    *)
        printf "%s" "$1"
        ;;
    esac
}

# Print the command required by a canonical CMake generator (empty if unknown).
mbt_generator_command() {
    case "$1" in
    Ninja)
        printf "ninja"
        ;;
    "Unix Makefiles")
        printf "make"
        ;;
    *)
        printf ""
        ;;
    esac
}

mbt_build() {
    local build_dir="$1"
    local generator="$2"
    local use_ccache="$3"
    local device="$4"
    local jobs="$5"
    local target="$6"
    local clean_build="$7"
    shift 7
    if [[ "$#" -lt 2 ]]; then
        mbt_die "internal error: mbt_build expected extra arg array names"
    fi

    local -n cmake_extra_args_ref="$1"
    local -a cmake_extra_args=("${cmake_extra_args_ref[@]}")
    shift
    local -n build_extra_args_ref="$1"
    local -a build_extra_args=("${build_extra_args_ref[@]}")
    local -a cmake_args build_args device_args
    local marker_file="$build_dir/.mbt_device"
    local previous_device=""

    if [[ "$clean_build" -eq 1 ]]; then
        mbt_clean "$build_dir"
        return 0
    else
        if [[ -f "$marker_file" ]]; then
            previous_device="$(<"$marker_file")"
        elif [[ -f "$build_dir/CMakeCache.txt" ]]; then
            previous_device="$(mbt_detect_cached_device "$build_dir" 2>/dev/null || true)"
        fi

        if [[ -n "$previous_device" ]] && [[ "$previous_device" != "$device" ]]; then
            mbt_log "device changed ($previous_device -> $device), cleaning build directory: $build_dir"
            rm -rf "$build_dir"
        fi
    fi

    mkdir -p "$build_dir"

    device_args=()
    mbt_device_args "$device" >/dev/null || mbt_die "unsupported device preset: $device"
    mapfile -t device_args < <(mbt_device_args "$device")

    if [[ "$generator" == "Ninja" ]] && ! mbt_command_exists ninja; then
        if mbt_command_exists make; then
            mbt_log "ninja not found; falling back to Unix Makefiles."
            generator="Unix Makefiles"
        else
            mbt_die "ninja not found and make is unavailable. Install dependencies or set a working generator."
        fi
    fi

    cmake_args=(
        -S "$SCRIPT_PATH"
        -B "$build_dir"
        -G "$generator"
        "-DUSE_CCACHE=$use_ccache"
    )
    cmake_args+=("${device_args[@]}")
    cmake_args+=("${cmake_extra_args[@]}")

    mbt_log "configuring build for $device in $build_dir"
    if ! cmake "${cmake_args[@]}"; then
        mbt_report_build_error
        return 1
    fi
    printf "%s\n" "$device" > "$marker_file"

    build_args=(--build "$build_dir" --parallel "$jobs")
    if [[ -n "$target" ]]; then
        build_args+=(--target "$target")
    fi
    build_args+=("${build_extra_args[@]}")

    mbt_log "building..."
    if ! cmake "${build_args[@]}"; then
        mbt_report_build_error
        return 1
    fi
    mbt_log "build complete. Outputs are in $build_dir."
    mbt_log "The bare binary (for the hackrf_spiflash host tool), excluding external apps, is located at $build_dir/firmware/portapack-mayhem-firmware.bin"
    mbt_log "The full tar.gz package (for MayhemHub and the Flash Utility OTA app), including external apps and the firmware file, is located at $build_dir/firmware/portapack-mayhem_OCI.ppfw.tar"
    mbt_log "If you have the dev's SD card switcher hardware, the fast flash script is at $build_dir/flash.py"
    # have to hard code the name here cuz it's too expensive to read cmake for just a file name.
}

# Compute elapsed wall-clock seconds (with 2 decimals) between two `date +%s.%N` stamps.
mbt_elapsed() {
    awk -v s="$1" -v e="$2" 'BEGIN { printf "%.2f", e - s }'
}

# Format seconds as a human-friendly "MmSS.ss" (or "SS.ss" under a minute).
mbt_format_seconds() {
    awk -v t="$1" 'BEGIN {
        if (t < 0) t = 0
        m = int(t / 60)
        s = t - m * 60
        if (m > 0) printf "%dm%05.2fs", m, s
        else printf "%.2fs", s
    }'
}

# Run one full clean build and print elapsed seconds on stdout.
# All progress/logging goes to stderr; build output is captured to a per-cell log.
# Args: cell_dir generator use_ccache device jobs target ccache_dir log_file  cmake_extra_array_name
mbt_bench_cell() {
    local cell_dir="$1" generator="$2" use_ccache="$3" device="$4" jobs="$5"
    local target="$6" ccache_dir="$7" log_file="$8"
    shift 8
    local -n cmake_extra_ref="$1"
    local -a cmake_extra_args=("${cmake_extra_ref[@]}")
    local -a device_args cmake_args build_args
    local start end status=0

    rm -rf "$cell_dir"
    mkdir -p "$cell_dir"

    # libopencm3 builds in-source, so it survives `rm -rf "$cell_dir"`. Without
    # this, only the first cell would pay its compile cost and every later cell
    # would look artificially fast, biasing the whole comparison.
    mbt_clean_libopencm3 1 || true

    mapfile -t device_args < <(mbt_device_args "$device")

    cmake_args=(
        -S "$SCRIPT_PATH"
        -B "$cell_dir"
        -G "$generator"
        "-DUSE_CCACHE=$use_ccache"
    )
    cmake_args+=("${device_args[@]}")
    cmake_args+=("${cmake_extra_args[@]}")

    build_args=(--build "$cell_dir" --parallel "$jobs")
    if [[ -n "$target" ]]; then
        build_args+=(--target "$target")
    fi

    start="$(date +%s.%N)"
    (
        if [[ -n "$ccache_dir" ]]; then
            export CCACHE_DIR="$ccache_dir"
        fi
        cmake "${cmake_args[@]}" && cmake "${build_args[@]}"
    ) >"$log_file" 2>&1 || status=$?
    end="$(date +%s.%N)"

    if [[ "$status" -ne 0 ]]; then
        printf "FAILED"
        return "$status"
    fi

    mbt_elapsed "$start" "$end"
}

# Populate a ccache directory without timing (used when a warm run is requested
# but no cold run precedes it to fill the cache).
mbt_bench_populate() {
    local cell_dir="$1" generator="$2" device="$3" jobs="$4" target="$5"
    local ccache_dir="$6" log_file="$7"
    shift 7
    mbt_bench_cell "$cell_dir" "$generator" "ON" "$device" "$jobs" "$target" \
        "$ccache_dir" "$log_file" "$1" >/dev/null
}

mbt_benchmark() {
    local base_dir="$1" device="$2" jobs="$3" target="$4"
    local generators_csv="$5" ccache_csv="$6"
    shift 6
    local -n bench_cmake_extra_ref="$1"
    local -a bench_extra_args=("${bench_cmake_extra_ref[@]}")

    local -a want_generators=() generators=() modes=()
    local raw g cmd mode

    # Resolve requested generators (auto = every generator whose tool is present).
    if [[ -z "$generators_csv" || "$generators_csv" == "auto" ]]; then
        want_generators=("Ninja" "Unix Makefiles")
    else
        IFS=',' read -ra raw_gens <<< "$generators_csv"
        for raw in "${raw_gens[@]}"; do
            [[ -z "$raw" ]] && continue
            want_generators+=("$(mbt_resolve_generator "$raw")")
        done
    fi

    for g in "${want_generators[@]}"; do
        cmd="$(mbt_generator_command "$g")"
        if [[ -z "$cmd" ]]; then
            mbt_error "skipping unknown generator: $g"
            continue
        fi
        if ! mbt_command_exists "$cmd"; then
            mbt_error "skipping generator '$g' ($cmd not installed)."
            continue
        fi
        generators+=("$g")
    done

    if [[ "${#generators[@]}" -eq 0 ]]; then
        mbt_die "no usable generators for benchmark (need ninja and/or make)."
    fi

    # Resolve ccache modes: off | cold | warm.
    if [[ -z "$ccache_csv" ]]; then
        ccache_csv="off,cold,warm"
    fi
    local -A mode_seen=()
    IFS=',' read -ra raw_modes <<< "$ccache_csv"
    for mode in "${raw_modes[@]}"; do
        mode="$(printf "%s" "$mode" | tr '[:upper:]' '[:lower:]')"
        [[ -z "$mode" ]] && continue
        case "$mode" in
        off | cold | warm) ;;
        on) mode="cold" ;; # treat plain "on" as a cold measurement
        *) mbt_die "unknown ccache mode: $mode (use off, cold, warm)" ;;
        esac
        if [[ -z "${mode_seen[$mode]:-}" ]]; then
            modes+=("$mode")
            mode_seen[$mode]=1
        fi
    done
    [[ "${#modes[@]}" -eq 0 ]] && mbt_die "no ccache modes selected."

    local needs_ccache=0
    for mode in "${modes[@]}"; do
        [[ "$mode" != "off" ]] && needs_ccache=1
    done
    if [[ "$needs_ccache" -eq 1 ]] && ! mbt_command_exists ccache; then
        mbt_die "ccache modes requested but ccache is not installed. Install it or use --bench-ccache off."
    fi

    mkdir -p "$base_dir"
    local log_dir="$base_dir/logs"
    mkdir -p "$log_dir"

    mbt_log "benchmark: device=$device jobs=$jobs generators=[${generators[*]}] ccache=[${modes[*]}]"
    [[ -n "$target" ]] && mbt_log "benchmark: target=$target"
    mbt_log "benchmark: results and per-cell logs under $base_dir"
    mbt_log "benchmark: each cell is a full clean build; this can take a while."

    # Parallel result arrays.
    local -a r_gen=() r_mode=() r_secs=() r_ok=()
    local cell_dir ccache_dir log_file secs cell_status label

    for g in "${generators[@]}"; do
        # Per-generator, isolated ccache dir so "cold" is truly cold and the
        # user's real cache is never touched. Cache keys are generator-agnostic,
        # so each generator needs its own fresh dir.
        ccache_dir=""
        if [[ "$needs_ccache" -eq 1 ]]; then
            ccache_dir="$base_dir/ccache-$(printf "%s" "$g" | tr ' ' '-')"
            rm -rf "$ccache_dir"
            mkdir -p "$ccache_dir"
        fi

        local cold_done=0
        for mode in "${modes[@]}"; do
            label="$g / ccache=$mode"
            log_file="$log_dir/$(printf "%s" "$g" | tr ' ' '-')-$mode.log"

            case "$mode" in
            off)
                mbt_log "running: $label"
                secs="$(mbt_bench_cell "$base_dir/cell" "$g" "OFF" "$device" \
                    "$jobs" "$target" "" "$log_file" bench_extra_args)" && cell_status=0 || cell_status=$?
                ;;
            cold)
                rm -rf "$ccache_dir" && mkdir -p "$ccache_dir"
                mbt_log "running: $label (empty cache)"
                secs="$(mbt_bench_cell "$base_dir/cell" "$g" "ON" "$device" \
                    "$jobs" "$target" "$ccache_dir" "$log_file" bench_extra_args)" && cell_status=0 || cell_status=$?
                [[ "$cell_status" -eq 0 ]] && cold_done=1
                ;;
            warm)
                if [[ "$cold_done" -eq 0 ]]; then
                    mbt_log "priming cache for: $label (untimed)"
                    rm -rf "$ccache_dir" && mkdir -p "$ccache_dir"
                    if ! mbt_bench_populate "$base_dir/cell" "$g" "$device" \
                        "$jobs" "$target" "$ccache_dir" "$log_dir/$(printf "%s" "$g" | tr ' ' '-')-prime.log" bench_extra_args; then
                        mbt_error "cache priming failed for $label; skipping."
                        r_gen+=("$g"); r_mode+=("$mode"); r_secs+=("0"); r_ok+=("0")
                        continue
                    fi
                fi
                mbt_log "running: $label (populated cache)"
                secs="$(mbt_bench_cell "$base_dir/cell" "$g" "ON" "$device" \
                    "$jobs" "$target" "$ccache_dir" "$log_file" bench_extra_args)" && cell_status=0 || cell_status=$?
                ;;
            esac

            if [[ "$cell_status" -ne 0 ]]; then
                mbt_error "cell failed: $label (see $log_file)"
                r_gen+=("$g"); r_mode+=("$mode"); r_secs+=("0"); r_ok+=("0")
            else
                mbt_log "  -> $(mbt_format_seconds "$secs") ($secs s)"
                r_gen+=("$g"); r_mode+=("$mode"); r_secs+=("$secs"); r_ok+=("1")
            fi
        done
    done

    rm -rf "$base_dir/cell"

    # Summary table.
    printf "\n"
    mbt_log "benchmark summary (device=$device, jobs=$jobs)"
    printf "  %-16s %-8s %12s %10s\n" "generator" "ccache" "time" "vs off"
    printf "  %-16s %-8s %12s %10s\n" "---------" "------" "----" "------"

    local i baseline speedup
    for ((i = 0; i < ${#r_gen[@]}; i++)); do
        # Find the "off" baseline for the same generator, if measured.
        baseline=""
        local j
        for ((j = 0; j < ${#r_gen[@]}; j++)); do
            if [[ "${r_gen[$j]}" == "${r_gen[$i]}" && "${r_mode[$j]}" == "off" && "${r_ok[$j]}" == "1" ]]; then
                baseline="${r_secs[$j]}"
                break
            fi
        done

        if [[ "${r_ok[$i]}" != "1" ]]; then
            printf "  %-16s %-8s %12s %10s\n" "${r_gen[$i]}" "${r_mode[$i]}" "FAILED" "-"
            continue
        fi

        if [[ -n "$baseline" && "${r_mode[$i]}" != "off" ]]; then
            speedup="$(awk -v b="$baseline" -v t="${r_secs[$i]}" 'BEGIN { if (t > 0) printf "%.2fx", b / t; else printf "-" }')"
        else
            speedup="-"
        fi
        printf "  %-16s %-8s %12s %10s\n" "${r_gen[$i]}" "${r_mode[$i]}" "$(mbt_format_seconds "${r_secs[$i]}")" "$speedup"
    done
    printf "\n"
    mbt_log "'vs off' > 1x means faster than the same generator's ccache=off build."
    mbt_log "cold = empty cache (populate cost); warm = pre-populated cache (the ccache win)."
}

main() {
    local command="build"
    local quickstart=0
    local device=""
    local use_ccache="ON"
    local with_deps=0
    local with_submodule_sync=1
    local with_toolchain=1
    local build_dir="$SCRIPT_PATH/build"
    local build_dir_explicit=0
    local generator="Ninja"
    local jobs
    local target=""
    local clean_build=0
    local non_interactive=0
    local benchmark_generators=""
    local benchmark_ccache=""
    local -a cmake_extra_args=()
    local -a build_extra_args=()

    FORCE_TOOLCHAIN=0
    jobs="$(mbt_default_jobs)"

    if [[ "$#" -eq 0 ]]; then
        quickstart=1
        with_deps=1
    fi

    if [[ "$#" -gt 0 ]]; then
        case "$1" in
        build|deps|toolchain|doctor|shell|benchmark)
            command="$1"
            shift
            ;;
        -h|--help|help)
            mbt_print_help
            exit 0
            ;;
        esac
    fi

    while [[ "$#" -gt 0 ]]; do
        case "$1" in
        -d|--device)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            device="$2"
            shift 2
            ;;
        --ccache)
            use_ccache="ON"
            shift
            ;;
        --no-ccache)
            use_ccache="OFF"
            shift
            ;;
        --with-deps)
            with_deps=1
            shift
            ;;
        --no-deps)
            with_deps=0
            shift
            ;;
        --with-submodule-sync)
            with_submodule_sync=1
            shift
            ;;
        --no-submodule-sync)
            with_submodule_sync=0
            shift
            ;;
        --with-toolchain)
            with_toolchain=1
            shift
            ;;
        --no-toolchain)
            with_toolchain=0
            shift
            ;;
        --force-toolchain)
            FORCE_TOOLCHAIN=1
            with_toolchain=1
            shift
            ;;
        -B|--build-dir)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            build_dir="$2"
            build_dir_explicit=1
            shift 2
            ;;
        --bench-generators)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            benchmark_generators="$2"
            shift 2
            ;;
        --bench-generators=*)
            benchmark_generators="${1#*=}"
            shift
            ;;
        --bench-ccache)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            benchmark_ccache="$2"
            shift 2
            ;;
        --bench-ccache=*)
            benchmark_ccache="${1#*=}"
            shift
            ;;
        -G|--generator)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            generator="$2"
            shift 2
            ;;
        -j|--jobs)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            jobs="$2"
            shift 2
            ;;
        --target)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            target="$2"
            shift 2
            ;;
        --clean)
            clean_build=1
            shift
            ;;
        --cmake-arg)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            cmake_extra_args+=("$2")
            shift 2
            ;;
        --cmake-arg=*)
            cmake_extra_args+=("${1#*=}")
            shift
            ;;
        --build-arg)
            [[ "$#" -ge 2 ]] || mbt_die "$1 requires a value"
            build_extra_args+=("$2")
            shift 2
            ;;
        --build-arg=*)
            build_extra_args+=("${1#*=}")
            shift
            ;;
        -y|--non-interactive)
            non_interactive=1
            shift
            ;;
        -h|--help)
            mbt_print_help
            exit 0
            ;;
        *)
            mbt_die "unknown option: $1"
            ;;
        esac
    done

    if ! mbt_validate_jobs "$jobs"; then
        mbt_die "invalid jobs value: $jobs"
    fi

    case "$command" in
    deps)
        mbt_install_deps
        exit 0
        ;;
    toolchain)
        NO_TOOLCHAIN_DOWNLOAD=0
        mbt_enable_toolchain_env
        mbt_log "toolchain ready: $SCRIPT_PATH/armbin"
        exit 0
        ;;
    doctor)
        mbt_doctor
        exit $?
        ;;
    shell)
        if [[ "$with_toolchain" -eq 1 ]]; then
            mbt_enable_toolchain_env
        else
            mbt_use_existing_toolchain_env
        fi
        mbt_log "spawning shell with toolchain exported in this session. Use 'exit' to leave."
        exec "${SHELL:-/bin/bash}" -i
        ;;
    build)
        ;;
    benchmark)
        # Never benchmark into the user's working ./build dir; a benchmark
        # wipes its build dir between cells. Use a dedicated dir by default.
        if [[ "$build_dir_explicit" -eq 0 ]]; then
            build_dir="$SCRIPT_PATH/build-bench"
        fi
        ;;
    *)
        mbt_die "unsupported command: $command"
        ;;
    esac

    if [[ "$clean_build" -eq 1 ]]; then
        mbt_clean "$build_dir"
        exit 0
    fi

    if [[ "$with_deps" -eq 1 ]]; then
        mbt_install_deps
    fi

    if [[ "$with_submodule_sync" -eq 1 ]]; then
        mbt_sync_submodules
    fi

    if [[ "$with_toolchain" -eq 1 ]]; then
        mbt_enable_toolchain_env
    else
        mbt_use_existing_toolchain_env
    fi

    if [[ -n "$device" ]]; then
        device="$(mbt_normalize_device "$device" 2>/dev/null || true)"
    fi

    if [[ -z "$device" ]]; then
        if [[ "$non_interactive" -eq 1 ]]; then
            mbt_die "--device is required when --non-interactive is set"
        fi
        if [[ ! -t 0 ]]; then
            mbt_die "missing --device and no interactive terminal available"
        fi
        device="$(mbt_prompt_device)" || mbt_die "failed to read device selection"
    fi

    if [[ "$quickstart" -eq 1 ]]; then
        mbt_log "quickstart mode enabled."
    fi

    if [[ "$command" == "benchmark" ]]; then
        mbt_benchmark "$build_dir" "$device" "$jobs" "$target" \
            "$benchmark_generators" "$benchmark_ccache" cmake_extra_args
        exit $?
    fi

    mbt_build "$build_dir" "$generator" "$use_ccache" "$device" "$jobs" "$target" "$clean_build" \
        cmake_extra_args[@] build_extra_args[@]
}

main "$@"