#!/usr/bin/env bash
set -euo pipefail

MODE="native"

while [[ $# -gt 0 ]]; do
  case "$1" in
    --mode)
      MODE="${2:-}"
      shift 2
      ;;
    *)
      echo "usage: $0 --mode <native|nix-host|nix-shell>"
      exit 2
      ;;
  esac
done

if [[ -z "${MODE}" ]]; then
  echo "error: --mode is required"
  exit 2
fi

OS="$(uname -s)"
FAILED=0

print_install_hint() {
  local cmd="$1"

  if [[ "${OS}" == "Darwin" ]]; then
    case "${cmd}" in
      nix) echo "  install: sh <(curl -L https://nixos.org/nix/install) --daemon" ;;
      cargo|rustc|rustup) echo "  install: curl https://sh.rustup.rs -sSf | sh" ;;
      just) echo "  install: brew install just" ;;
      rg) echo "  install: brew install ripgrep" ;;
      fd) echo "  install: brew install fd" ;;
      tree) echo "  install: brew install tree" ;;
      cargo-watch) echo "  install: cargo install cargo-watch" ;;
      cargo-nextest) echo "  install: cargo install cargo-nextest --locked" ;;
      *) echo "  install: use your package manager to install '${cmd}'" ;;
    esac
    return
  fi

  case "${cmd}" in
    nix) echo "  install: sh <(curl -L https://nixos.org/nix/install) --daemon" ;;
    cargo|rustc|rustup) echo "  install: curl https://sh.rustup.rs -sSf | sh" ;;
    just) echo "  install: sudo apt update && sudo apt install -y just" ;;
    rg) echo "  install: sudo apt update && sudo apt install -y ripgrep" ;;
    fd) echo "  install: sudo apt update && sudo apt install -y fd-find" ;;
    tree) echo "  install: sudo apt update && sudo apt install -y tree" ;;
    cargo-watch) echo "  install: cargo install cargo-watch" ;;
    cargo-nextest) echo "  install: cargo install cargo-nextest --locked" ;;
    *) echo "  install: use your package manager to install '${cmd}'" ;;
  esac
}

require_cmd() {
  local cmd="$1"
  if command -v "${cmd}" >/dev/null 2>&1; then
    echo "ok: ${cmd}"
  else
    echo "missing: ${cmd}"
    print_install_hint "${cmd}"
    FAILED=1
  fi
}

warn_if_missing() {
  local cmd="$1"
  if command -v "${cmd}" >/dev/null 2>&1; then
    echo "ok(optional): ${cmd}"
  else
    echo "missing(optional): ${cmd}"
    print_install_hint "${cmd}"
  fi
}

check_xcode_clt() {
  if [[ "${OS}" != "Darwin" ]]; then
    return
  fi

  if xcode-select -p >/dev/null 2>&1; then
    echo "ok: xcode-command-line-tools"
  else
    echo "missing: xcode-command-line-tools"
    echo "  install: xcode-select --install"
    FAILED=1
  fi
}

print_context_note() {
  if [[ -f "ai/context/project-context.md" ]]; then
    echo "ok: ai/context/project-context.md exists (generated file)"
  else
    echo "info: ai/context/project-context.md is generated and currently missing"
    echo "  generate with: just context"
    echo "  or: ./ai/scripts/build-context.sh"
  fi
}

check_native() {
  echo "mode: native"
  require_cmd cargo
  require_cmd rustc
  require_cmd just
  require_cmd rg
  require_cmd fd
  require_cmd tree

  if command -v rustup >/dev/null 2>&1; then
    if rustup component list --installed | rg -q "^rustfmt"; then
      echo "ok: rustup component rustfmt"
    else
      echo "missing: rustup component rustfmt"
      echo "  install: rustup component add rustfmt"
      FAILED=1
    fi

    if rustup component list --installed | rg -q "^clippy"; then
      echo "ok: rustup component clippy"
    else
      echo "missing: rustup component clippy"
      echo "  install: rustup component add clippy"
      FAILED=1
    fi
  else
    echo "missing: rustup"
    print_install_hint rustup
    FAILED=1
  fi

  warn_if_missing cargo-watch
  warn_if_missing cargo-nextest
  check_xcode_clt
  print_context_note
}

check_nix_host() {
  echo "mode: nix-host"
  require_cmd nix
  check_xcode_clt
}

check_nix_shell() {
  echo "mode: nix-shell"
  require_cmd cargo
  require_cmd rustc
  require_cmd just
  require_cmd rg
  require_cmd fd
  require_cmd tree
  require_cmd cargo-watch
  require_cmd cargo-nextest
  check_xcode_clt
  print_context_note
}

case "${MODE}" in
  native) check_native ;;
  nix-host) check_nix_host ;;
  nix-shell) check_nix_shell ;;
  *)
    echo "error: unknown mode '${MODE}'"
    echo "usage: $0 --mode <native|nix-host|nix-shell>"
    exit 2
    ;;
esac

if [[ "${FAILED}" -ne 0 ]]; then
  echo "requirements check: FAILED"
  exit 1
fi

echo "requirements check: OK"