#!/usr/bin/env bash
set -euo pipefail
action="${1:?action is required}"
root="${STEM_REPO:-${CARD_ROOT:-$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)}}"
profile="${STEM_PROFILE:-native-amd64}"
target="${STEM_TARGET:-native}"
selector="${STEM_TASK:-task1}"
card_id="$(sed -n 's/^card: cpp\///p' "$root/lesson-flow.yaml" | head -n1)"
resolve_task() {
  local value="${1,,}"
  if [[ "$value" =~ ^(task|t)?[-_]?0*([1-3])($|[-_].*) ]]; then printf 'task%02d\n' "${BASH_REMATCH[2]}"; return; fi
  [[ "$value" =~ ^task0[1-3]$ ]] && { printf '%s\n' "$value"; return; }
  printf 'Unknown task selector: %s\n' "$1" >&2; exit 2
}
task="$(resolve_task "$selector")"
artifact_dir="$root/.stem/artifacts/$profile/$target/$task"
binary="$artifact_dir/program"
mkdir -p "$artifact_dir"
compile_task() {
  local selected="$1" output="$2"
  mapfile -t sources < <(find "$root/src/$selected" -maxdepth 1 -type f -name '*.cpp' | sort)
  [[ ${#sources[@]} -gt 0 ]] || { printf 'No C++ sources for %s\n' "$selected" >&2; exit 2; }
  "${CXX:-g++}" -std=c++20 -Wall -Wextra -Wpedantic -Werror -O0 -g3 -fno-omit-frame-pointer -I"$root/src/$selected" "${sources[@]}" -o "$output"
}
verify_task() {
  local selected="$1" output="$2" actual="$artifact_dir/actual.txt"
  compile_task "$selected" "$output"
  "$output" >"$actual"
  diff -u "$root/tests/expected/$selected.txt" "$actual"
}
case "$profile:$target:$action" in
  native-amd64:native:build)
    for item in task01 task02 task03; do
      current="$root/.stem/artifacts/$profile/$target/$item"
      mkdir -p "$current"
      compile_task "$item" "$current/program"
    done
    printf 'BUILD %s standard=c++20 tasks=3\n' "$card_id"
    ;;
  native-amd64:native:test|native-amd64:native:run)
    verify_task "$task" "$binary"
    printf 'PASS %s %s standard=c++20\n' "$card_id" "$task"
    ;;
  native-amd64:native:debug)
    verify_task "$task" "$binary"
    trace="$artifact_dir/debug.log"
    if command -v gdb >/dev/null 2>&1; then
      gdb -q -batch -ex 'set pagination off' -ex 'set debuginfod enabled off' -ex 'break main' -ex run -ex 'info source' -ex 'info args' -ex continue "$binary" >"$trace" 2>&1
    else
      { printf 'gdb unavailable; binary evidence follows\n'; "${NM:-nm}" -C "$binary" | head -n 80; "$binary"; } >"$trace" 2>&1
    fi
    cat "$trace"
    [[ -s "$trace" ]]
    printf 'TRACE %s %s log=%s\n' "$card_id" "$task" "$trace"
    ;;
  *) printf 'Unsupported profile/target/action: %s/%s/%s\n' "$profile" "$target" "$action" >&2; exit 2 ;;
esac