#!/usr/bin/env bash
# SUM Parts - PHASE B: the GPU work
#
# Assumes run_setup.sh already finished (it checks for the marker). Everything
# here needs the card to itself:
#
#   preflight -> choose voxel_max (measured) -> train -> evaluate
#
# Waits for the GPU rather than failing when it is busy: if another job holds
# the card, this parks until enough VRAM frees up. So it can be started ahead
# of time and left alone.
#
# Usage:
#   bash scripts/run_train.sh
#   bash scripts/run_train.sh --detach
#   RUN_DRYRUN=1 bash scripts/run_train.sh     # preflight only
set -uo pipefail

SCRIPTS="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
SETUP_MARKER="$HOME/sum-parts/runs/setup/SETUP_DONE"
OUT="$HOME/sum-parts/runs/train"
LOG="$OUT/train_phase.log"
STATUS="$OUT/STATUS"
DONE_MARKER="$OUT/TRAIN_DONE"

CFG="${CFG:-pointvector-xl}"
EPOCHS="${EPOCHS:-100}"
VAL_FREQ="${VAL_FREQ:-5}"
# tried high to low; first one that actually fits in VRAM wins.
# 64000 is the paper setting and needs ~16.5 GB.
VOXEL_CANDIDATES="${VOXEL_CANDIDATES:-64000 48000 40000 32000 24000}"

# how long to wait for someone else's job to release the card
GPU_WAIT_MINUTES="${GPU_WAIT_MINUTES:-720}"
GPU_FREE_MB="${GPU_FREE_MB:-16000}"

if [ "${1:-}" = "--detach" ]; then
    mkdir -p "$OUT"
    echo "detaching; log: $LOG"
    setsid nohup bash "${BASH_SOURCE[0]}" > "$OUT/nohup.out" 2>&1 < /dev/null &
    sleep 2
    pgrep -af "run_train.sh" | grep -v detach || true
    exit 0
fi

mkdir -p "$OUT"
exec > >(tee -a "$LOG") 2>&1

PHASE="starting"
STARTED=$(date '+%F %T')
VOXEL_MAX=""

say()   { echo "[$(date '+%F %T')] $*"; }
head_() { echo; echo "════ $* ════"; }

write_status() {
    {
        echo "state    : $1"
        echo "phase    : $PHASE"
        echo "cfg      : $CFG"
        echo "voxel_max: ${VOXEL_MAX:-(not chosen yet)}"
        echo "started  : $STARTED"
        echo "updated  : $(date '+%F %T')"
        [ -n "${EXTRA:-}" ] && echo "note     : $EXTRA"
        echo "log      : $LOG"
    } > "$STATUS"
}

die() {
    say "GIVING UP in phase '$PHASE': $*"
    EXTRA="$*" write_status "FAILED"
    exit 1
}

STEP_RETRIES="${STEP_RETRIES:-4}"
STEP_BACKOFF="${STEP_BACKOFF:-60}"

step() {
    PHASE="$1"; shift
    head_ "$PHASE"
    write_status "running"
    local attempt=1 wait=$STEP_BACKOFF
    while :; do
        if "$@"; then
            [ "$attempt" -gt 1 ] && say "phase '$PHASE' succeeded on attempt $attempt"
            return 0
        fi
        [ "$attempt" -ge "$STEP_RETRIES" ] && die "$* (failed $attempt times)"
        say "phase '$PHASE' failed (attempt $attempt/$STEP_RETRIES); retrying in ${wait}s"
        EXTRA="retrying $PHASE ($attempt/$STEP_RETRIES)" write_status "retrying"
        sleep "$wait"
        attempt=$((attempt + 1)); wait=$((wait * 2))
    done
}

step_once() {
    PHASE="$1"; shift
    head_ "$PHASE"
    write_status "running"
    "$@" || die "$*"
}

# ---------------------------------------------------------------- preflight

preflight() {
    local fail=0

    say "checking phase A completed"
    if [ -f "$SETUP_MARKER" ]; then
        say "  marker present: $SETUP_MARKER"
    else
        say "  MISSING: $SETUP_MARKER"
        say "  run phase A first:  bash scripts/run_setup.sh"
        fail=1
    fi

    say "checking environment"
    if [ -x "$HOME/miniconda3/bin/conda" ]; then
        source "$HOME/miniconda3/etc/profile.d/conda.sh"
        if conda env list | grep -q '^sumparts '; then
            say "  conda env sumparts present"
        else
            say "  MISSING: conda env 'sumparts'"; fail=1
        fi
    else
        say "  MISSING: miniconda"; fail=1
    fi

    say "checking data"
    local d="$HOME/sum-parts/data/face_labeling/texsp_pcl"
    if [ -d "$d/train" ]; then
        say "  train/val/test = $(find -L "$d/train" -name '*.ply' | wc -l)/$(find -L "$d/val" -name '*.ply' 2>/dev/null | wc -l)/$(find -L "$d/test" -name '*.ply' | wc -l)"
    else
        say "  MISSING: $d/train"; fail=1
    fi

    say "checking GPU driver"
    if ! command -v nvidia-smi > /dev/null; then
        say "  MISSING: nvidia-smi -- no GPU visible, and this phase cannot run without one"
        fail=1
    else
        nvidia-smi --query-gpu=name,memory.total,memory.used,utilization.gpu \
                   --format=csv,noheader | sed 's/^/  /'
    fi

    [ "$fail" -eq 0 ] || return 1
    say "preflight OK"
}

# ------------------------------------------------------------ wait for GPU

wait_for_gpu() {
    local deadline=$(( $(date +%s) + GPU_WAIT_MINUTES * 60 ))
    local total used free

    total=$(nvidia-smi --query-gpu=memory.total --format=csv,noheader,nounits | head -1)
    say "card has ${total} MiB; waiting until ${GPU_FREE_MB} MiB is free"
    say "(will wait up to ${GPU_WAIT_MINUTES} minutes)"

    while :; do
        used=$(nvidia-smi --query-gpu=memory.used --format=csv,noheader,nounits | head -1)
        free=$(( total - used ))
        if [ "$free" -ge "$GPU_FREE_MB" ]; then
            say "  ${free} MiB free -- proceeding"
            return 0
        fi
        if [ "$(date +%s)" -ge "$deadline" ]; then
            say "  timed out with only ${free} MiB free"
            say "  continuing anyway; voxel_max will be measured against what is actually available"
            return 0
        fi
        EXTRA="waiting for GPU (${free} MiB free, need ${GPU_FREE_MB})" write_status "waiting"
        say "  ${free} MiB free, need ${GPU_FREE_MB} -- checking again in 5 min"
        sleep 300
    done
}

# ---------------------------------------------------------------- vram pick

pick_voxel_max() {
    say "measuring which voxel_max fits (high to low, first fit wins)"
    say "NOTE: on WSL2 an oversized value does not OOM -- the driver spills into"
    say "      host RAM and the run completes 25-100x slower. So this checks peak"
    say "      allocation instead of trusting that it 'worked'."

    source "$HOME/miniconda3/etc/profile.d/conda.sh"
    conda activate sumparts
    export WANDB_MODE=disabled WANDB_SILENT=true CUDA_HOME="$CONDA_PREFIX"
    export PYTORCH_CUDA_ALLOC_CONF="garbage_collection_threshold:0.7,max_split_size_mb:128"

    cd "$HOME/sum-parts/semantic_segmentation/PointNeXt_bundle/examples/segmentation" \
        || return 1

    local vm log line fits
    for vm in $VOXEL_CANDIDATES; do
        log="$OUT/vram_${vm}.log"
        say "  trying voxel_max=$vm"
        python -u "$SCRIPTS/bench_models.py" --iters 4 --voxel-max "$vm" \
            --cfgs "$CFG" > "$log" 2>&1
        line=$(grep -aE "^${CFG} +[0-9]" "$log" | tail -1)
        if [ -z "$line" ]; then
            say "    no result (OOM or error); see $log"
            continue
        fi
        say "    $(echo "$line" | awk '{print "peak", $5, " s/iter", $6}')"
        fits=$(echo "$line" | grep -o 'yes$' || true)
        if [ -n "$fits" ]; then
            VOXEL_MAX="$vm"
            say "  chosen: voxel_max=$VOXEL_MAX"
            return 0
        fi
        say "    does not fit -- would spill to host RAM"
    done

    say "  nothing fit; falling back to the smallest candidate"
    VOXEL_MAX=$(echo "$VOXEL_CANDIDATES" | awk '{print $NF}')
    return 0
}

# ---------------------------------------------------------------- train

do_train() {
    if [ -f "$DONE_MARKER" ]; then
        say "training already completed (marker: $DONE_MARKER)"
        return 0
    fi

    # train_watchdog only auto-discovers checkpoints written after it starts,
    # so hand it the newest one explicitly or a rerun restarts from epoch 1.
    local ckpt
    ckpt=$(find "$HOME/sum-parts/semantic_segmentation/PointNeXt_bundle/examples/segmentation/log/sumv2_triangle" \
           -name '*_ckpt_latest.pth' -printf '%T@ %p\n' 2>/dev/null \
           | sort -rn | head -1 | cut -d' ' -f2-)
    if [ -n "$ckpt" ]; then
        say "resuming from $(basename "$ckpt")"
    else
        say "no checkpoint found; starting fresh"
    fi

    say "training $CFG for $EPOCHS epochs at voxel_max=$VOXEL_MAX"
    CFG_VOXEL_MAX="$VOXEL_MAX" VAL_VOXEL_MAX="$VOXEL_MAX" \
    EPOCHS="$EPOCHS" VAL_FREQ="$VAL_FREQ" MAX_RETRIES=8 \
    RESUME_CKPT="$ckpt" \
        bash "$SCRIPTS/train_watchdog.sh" "$CFG" || return 1

    touch "$DONE_MARKER"
    return 0
}

do_eval() {
    bash "$SCRIPTS/final_eval.sh"  || say "final_eval non-zero (test split is blind; expected)"
    bash "$SCRIPTS/eval_coarse.sh" || say "eval_coarse non-zero"
    return 0
}

# ---------------------------------------------------------------- run

say "run_train starting (phase B - GPU required)"
say "cfg=$CFG epochs=$EPOCHS"
say "log: $LOG"
write_status "running"

step_once "preflight"   preflight

if [ -n "${RUN_DRYRUN:-}" ]; then
    say "DRYRUN set -- preflight passed, stopping before the real work"
    write_status "dryrun-ok"
    exit 0
fi

step_once "wait for GPU" wait_for_gpu
step "choose voxel_max"  pick_voxel_max
step "train"             do_train
step "evaluate"          do_eval

PHASE="done"
write_status "DONE"

head_ "PHASE B COMPLETE"
say "cfg       : $CFG"
say "voxel_max : $VOXEL_MAX"
grep -ahE 'Best ckpt' "$HOME/sum-parts/runs/"*/train.log 2>/dev/null | tail -2
if [ -f "$HOME/sum-parts/runs/coarse_eval/coarse.txt" ]; then
    echo
    echo "--- coarse (building / vegetation / vehicle / ground) ---"
    cat "$HOME/sum-parts/runs/coarse_eval/coarse.txt"
fi
say "TRAIN PHASE DONE"