#!/usr/bin/env bash
# Replace ALL rows of a single variant in a master results CSV with the rows
# from a re-run batch. Useful after running rerun_a1_full_all_datasets.sh:
#
#   bash scripts/replace_variant_in_results.sh \
#       outputs/cta_test_result/batch_20260602_215923/results_merged_<TS>.csv \
#       outputs/cta_test_result/batch_<NEW_TS>/results.csv \
#       --variant A1_full
#
# Behavior:
#   1. Verifies both CSVs share the same header.
#   2. Drops ALL rows where column `variant` matches --variant from the master.
#   3. Appends ALL rows where column `variant` matches --variant from the new
#      batch.
#   4. Writes a fresh merged file (default: <master>_replaced_<TS>.csv).
#
# The master and new-batch CSVs are NOT modified.
set -euo pipefail

usage() {
    grep -E '^#( |$)' "$0" | sed 's/^# \?//'
    exit "${1:-0}"
}

MASTER=""
NEW=""
VARIANT=""
OUT=""

while [[ $# -gt 0 ]]; do
    case "$1" in
        --variant) VARIANT="$2"; shift 2 ;;
        --out)     OUT="$2"; shift 2 ;;
        -h|--help) usage 0 ;;
        --*) echo "Unknown flag: $1" >&2; usage 1 ;;
        *)
            if [[ -z "$MASTER" ]]; then MASTER="$1"
            elif [[ -z "$NEW" ]]; then NEW="$1"
            else echo "Unexpected positional arg: $1" >&2; usage 1
            fi
            shift
            ;;
    esac
done

[[ -n "$MASTER" && -n "$NEW" && -n "$VARIANT" ]] || usage 1
[[ -f "$MASTER" ]] || { echo "Not a file: $MASTER" >&2; exit 1; }
[[ -f "$NEW" ]] || { echo "Not a file: $NEW" >&2; exit 1; }

if [[ -z "$OUT" ]]; then
    ts="$(date +%Y%m%d_%H%M%S)"
    OUT="${MASTER%.csv}_replaced_${ts}.csv"
fi

master_header="$(head -1 "$MASTER")"
new_header="$(head -1 "$NEW")"
if [[ "$master_header" != "$new_header" ]]; then
    echo "[replace] FATAL: headers differ." >&2
    echo "  MASTER: $master_header" >&2
    echo "  NEW:    $new_header" >&2
    exit 2
fi
header="$master_header"
var_col=$(echo "$header" | awk -F, '{
    for (i=1; i<=NF; i++) if ($i == "variant") { print i; exit }
}')
[[ -n "$var_col" ]] || { echo "[replace] FATAL: header missing variant column" >&2; exit 2; }

mkdir -p "$(dirname "$OUT")"

master_total=$(awk 'NR>1' "$MASTER" | wc -l)
master_match=$(awk -F, -v c="$var_col" -v v="$VARIANT" 'NR>1 && $c==v' "$MASTER" | wc -l)
new_total=$(awk 'NR>1' "$NEW" | wc -l)
new_match=$(awk -F, -v c="$var_col" -v v="$VARIANT" 'NR>1 && $c==v' "$NEW" | wc -l)
new_other=$((new_total - new_match))

echo "[replace] header: $(echo "$header" | awk -F, '{print NF}') columns; variant is column $var_col"
echo "[replace] MASTER: $master_total rows  ($VARIANT=$master_match, will be DROPPED)"
echo "[replace] NEW:    $new_total rows  ($VARIANT=$new_match, will be APPENDED)"
if [[ $new_other -gt 0 ]]; then
    echo "[replace] WARNING: NEW CSV has $new_other non-$VARIANT rows that will be IGNORED"
fi

{
    echo "$header"
    awk -F, -v c="$var_col" -v v="$VARIANT" 'NR>1 && $c!=v' "$MASTER"
    awk -F, -v c="$var_col" -v v="$VARIANT" 'NR>1 && $c==v' "$NEW"
} > "$OUT"

out_total=$(awk 'NR>1' "$OUT" | wc -l)
echo ""
echo "[replace] DONE."
echo "[replace] output: $OUT"
echo "[replace] $out_total rows = $((master_total - master_match)) master kept + $new_match new"
echo ""
echo "[replace] NEW $VARIANT rows (sanity preview):"
awk -F, -v c="$var_col" -v v="$VARIANT" 'NR>1 && $c==v' "$OUT" \
    | awk -F, '{printf "  %-20s %-8s %-15s acc=%s auc=%s\n", $1, $5, $3, $6, $7}'