#!/usr/bin/env bash

set -euo pipefail

harness_candidate_shells() {
  local shell
  local -a shells=()
  if [ -n "${SHELL:-}" ]; then
    shells+=("$SHELL")
  fi
  shells+=(zsh bash)

  local seen=""
  for shell in "${shells[@]}"; do
    if [ -z "$shell" ]; then
      continue
    fi
    if ! command -v "$shell" >/dev/null 2>&1; then
      continue
    fi
    shell="$(command -v "$shell")"
    case ":$seen:" in
      *":$shell:"*) continue ;;
    esac
    seen="${seen:+$seen:}$shell"
    printf "%s\n" "$shell"
  done
}

harness_find_cmd() {
  local cmd="$1"
  if [[ ! "$cmd" =~ ^[A-Za-z0-9_.+-]+$ ]]; then
    printf "invalid command name: %s\n" "$cmd" >&2
    return 2
  fi

  local found=""
  found="$(command -v "$cmd" 2>/dev/null || true)"
  if [ -n "$found" ] && [ -x "$found" ]; then
    printf "%s\n" "$found"
    return 0
  fi

  local shell
  while IFS= read -r shell; do
    found="$("$shell" -lic "command -v $cmd" 2>/dev/null | sed -n '1p' || true)"
    if [ -n "$found" ] && [ -x "$found" ]; then
      printf "%s\n" "$found"
      return 0
    fi
  done < <(harness_candidate_shells)

  return 1
}

harness_require_tool() {
  local cmd="$1"
  local found
  if ! found="$(harness_find_cmd "$cmd")"; then
    printf "missing required command: %s\n" "$cmd" >&2
    printf "looked in the current non-interactive PATH and login interactive shells\n" >&2
    return 1
  fi
  harness_prepend_tool_dir "$found"
  printf "%s\n" "$found"
}

harness_prepend_tool_dir() {
  local path="$1"
  local dir
  dir="$(dirname "$path")"
  case ":$PATH:" in
    *":$dir:"*) ;;
    *)
      PATH="$dir:$PATH"
      export PATH
      ;;
  esac
}

harness_run() {
  printf "+ %s\n" "$*" >&2
  "$@"
}