#!/usr/bin/env sh
# nina install script
# Run:  curl -fsSL kepr.uk/nina/install.sh | sh
# Or:   NINA_INSTALL_DIR=/usr/local/bin sh install.sh

set -e

FLAKE_URL="https://kepr.uk/nina/archive/HEAD.tar.gz"
RELEASES_URL="https://kepr.uk/api/nina/releases/latest"
INSTALL_DIR="${NINA_INSTALL_DIR:-$HOME/.local/bin}"
MIN_ZIG_MINOR=16

os="$(uname -s)"
arch="$(uname -m)"
case "${os}-${arch}" in
  Linux-x86_64)               platform="linux-x86_64"  ;;
  Linux-aarch64|Linux-arm64)  platform="linux-aarch64" ;;
  Darwin-arm64)               platform="macos-aarch64" ;;
  Darwin-x86_64)              platform="macos-x86_64"  ;;
  *)
    printf 'nina: unsupported platform %s-%s\n' "$os" "$arch" >&2
    exit 1 ;;
esac

have()  { command -v "$1" >/dev/null 2>&1; }
say()   { printf 'nina: %s\n' "$1"; }
die()   { say "error: $1" >&2; exit 1; }
blank() { printf '\n'; }
is_nixos() { [ -e /etc/NIXOS ]; }

fetch_text() {
  if have curl;   then curl -fsSL "$1"
  elif have wget; then wget -qO- "$1"
  else die "curl or wget required"; fi
}

fetch_file() {
  if have curl;   then curl -fsSL "$1" -o "$2"
  elif have wget; then wget -qO  "$2" "$1"
  else die "curl or wget required"; fi
}

# ── banner ────────────────────────────────────────────────────────────────────

banner() {
  cat <<'BANNER'

   _ __   _  _ __    __ _
  | '_ \ (_)| '_ \  / _` |
  | | | || || | | || (_| |
  |_| |_||_||_| |_| \__,_|

  NixOS Intuitive Navigation Assistant  ·  kepr.uk/nina

BANNER
}

# ── fetch source archive ──────────────────────────────────────────────────────

fetch_source() {
  srcdir="$(mktemp -d /tmp/nina-src.XXXXXX)"
  say "fetching source from Kepr..."
  fetch_file "$FLAKE_URL" "${srcdir}/nina.tar.gz" \
    || die "could not download source archive — check your connection"
  tar -xzf "${srcdir}/nina.tar.gz" -C "$srcdir" --strip-components=1 \
    || die "could not extract source archive"
  printf '%s' "$srcdir"
}

# ── binary install from Kepr ─────────────────────────────────────────────────

install_binary() {
  say "fetching release metadata..."
  meta="$(fetch_text "$RELEASES_URL" 2>/dev/null)" || return 1
  [ -n "$meta" ] || return 1

  if have python3; then
    version="$(printf '%s' "$meta" | python3 -c "
import sys, json
d = json.load(sys.stdin)
print(d.get('version') or '')
" 2>/dev/null)"
    dl_url="$(printf '%s' "$meta" | python3 -c "
import sys, json
d = json.load(sys.stdin)
print((d.get('platforms') or {}).get('${platform}', {}).get('url') or '')
" 2>/dev/null)"
    cksum="$(printf '%s' "$meta" | python3 -c "
import sys, json
d = json.load(sys.stdin)
p = (d.get('platforms') or {}).get('${platform}', {})
raw = p.get('blake3') or p.get('checksum') or ''
print(raw[len('blake3:'):] if raw.startswith('blake3:') else raw)
" 2>/dev/null)"
  elif have jq; then
    version="$(printf '%s' "$meta" | jq -r '.version // empty')"
    dl_url="$(printf '%s' "$meta" | jq -r ".platforms.\"${platform}\".url // empty")"
    cksum_raw="$(printf '%s' "$meta" | jq -r ".platforms.\"${platform}\".blake3 // .platforms.\"${platform}\".checksum // empty")"
    cksum="${cksum_raw#blake3:}"
  else
    version="$(printf '%s' "$meta" | grep -o '"version":"[^"]*"' | sed 's/"version":"//;s/"//')"
    plat_block="$(printf '%s' "$meta" | grep -o "\"${platform}\":{[^}]*}" | head -1)"
    dl_url="$(printf '%s' "$plat_block" | grep -o '"url":"[^"]*"' | sed 's/"url":"//;s/"//')"
    cksum=""
  fi

  [ -n "$dl_url" ] || return 1
  [ -n "$version" ] || version="latest"

  say "downloading nina ${version} for ${platform}..."
  tmpfile="$(mktemp /tmp/nina.XXXXXX)"
  fetch_file "$dl_url" "$tmpfile" || { rm -f "$tmpfile"; return 1; }

  if [ -n "$cksum" ] && have b3sum; then
    actual="$(b3sum --no-names "$tmpfile" 2>/dev/null | awk '{print $1}')"
    if [ "$actual" != "$cksum" ]; then
      say "checksum mismatch — aborting"
      rm -f "$tmpfile"
      return 1
    fi
    say "checksum verified"
  fi

  chmod +x "$tmpfile"
  mkdir -p "$INSTALL_DIR"
  mv "$tmpfile" "${INSTALL_DIR}/nina"
  say "installed nina ${version} → ${INSTALL_DIR}/nina"
  return 0
}

# ── NixOS: nix profile install (primary) ─────────────────────────────────────

nixos_profile_install() {
  have nix || return 1
  say "installing nina to ~/.nix-profile/bin/nina via nix profile..."
  blank
  if nix profile install "${FLAKE_URL}#nina"; then
    return 0
  fi
  blank
  say "nix profile install failed. Common causes:"
  say "  flakes not enabled — add to /etc/nix/nix.conf or ~/.config/nix/nix.conf:"
  say "    experimental-features = nix-command flakes"
  say "  once nina is installed: nina setup enables this automatically"
  blank
  return 1
}

# ── NixOS: nix-shell source build (fallback) ──────────────────────────────────

nixos_shell_build() {
  have nix-shell || return 1
  say "opening nix-shell with zig_0_16 and building nina from source..."
  blank
  srcdir="$(fetch_source)"
  nix-shell -p zig_0_16 \
    --run "cd '${srcdir}' && zig build -Doptimize=ReleaseSafe" \
    || die "build failed — see output above"
  mkdir -p "$INSTALL_DIR"
  cp "${srcdir}/zig-out/bin/nina" "${INSTALL_DIR}/nina"
  chmod +x "${INSTALL_DIR}/nina"
  blank
  say "installed from source → ${INSTALL_DIR}/nina"
  say "note: this binary was built outside of nix — adopt ~/nina.nix into your"
  say "configuration.nix to make it nix-managed."
}

# ── generate ~/nina.nix ───────────────────────────────────────────────────────

generate_nixos_module() {
  # Write ~/nina.nix without invoking shell substitution on the nix code inside.
  cat > "$HOME/nina.nix" <<'NIXEOF'
# ~/nina.nix — generated by the nina installer
#
# Declares nina as a NixOS system package.
#
# Add to /etc/nixos/configuration.nix:
#   imports = [ /home/YOUR_USER/nina.nix ];
# Then: sudo nixos-rebuild switch
#
# To update:  nina update  (or re-run the installer)
# To remove:  nina goodbye  (or delete this file, then nixos-rebuild switch)
#
# For flake-based configurations, add nina as a flake input instead:
#   inputs.nina.url = "https://kepr.uk/nina/archive/HEAD.tar.gz";
#   # in your nixosModules list: nina.nixosModules.default
#   # then set: programs.nina.enable = true;
{ ... }:
{
  imports = [
    "${builtins.fetchTarball "https://kepr.uk/nina/archive/HEAD.tar.gz"}/nixos-module.nix"
  ];
  programs.nina.enable = true;
}
NIXEOF
  blank
  say "generated ~/nina.nix for system-wide installation:"
  say "  1. add to /etc/nixos/configuration.nix:"
  say "       imports = [ /home/$(id -un)/nina.nix ];"
  say "  2. sudo nixos-rebuild switch"
}

# ── Zig version check ─────────────────────────────────────────────────────────

check_zig() {
  if ! have zig; then
    blank
    say "Zig not found. Building nina requires Zig 0.${MIN_ZIG_MINOR}+."
    blank
    say "  Download: https://ziglang.org/download/"
    if is_nixos; then
      say "  NixOS:    nix-shell -p zig_0_16 --run 'sh install.sh'"
    fi
    blank
    die "Zig 0.${MIN_ZIG_MINOR}+ required"
  fi

  zig_ver="$(zig version 2>/dev/null)"
  major="$(printf '%s' "$zig_ver" | cut -d. -f1)"
  minor="$(printf '%s' "$zig_ver" | cut -d. -f2)"
  ok=0
  [ "$major" -ge 1 ] 2>/dev/null && ok=1
  [ "$major" -eq 0 ] 2>/dev/null && [ "$minor" -ge "$MIN_ZIG_MINOR" ] 2>/dev/null && ok=1

  if [ "$ok" -ne 1 ]; then
    blank
    say "found zig ${zig_ver}, but nina requires Zig 0.${MIN_ZIG_MINOR}+."
    if is_nixos; then
      say "  run: nix-shell -p zig_0_16 --run 'sh install.sh'"
    else
      say "  update: https://ziglang.org/download/"
    fi
    blank
    die "Zig 0.${MIN_ZIG_MINOR}+ required; found ${zig_ver}"
  fi

  say "zig ${zig_ver} found"
}

# ── generic source build (non-NixOS) ─────────────────────────────────────────

build_from_source() {
  say "building from source..."
  check_zig

  if [ -f "build.zig" ] && [ -f "src/main.zig" ]; then
    srcdir="."
  else
    srcdir="$(fetch_source)"
  fi

  (cd "$srcdir" && zig build -Doptimize=ReleaseSafe) \
    || die "build failed — see output above"

  mkdir -p "$INSTALL_DIR"
  cp "${srcdir}/zig-out/bin/nina" "${INSTALL_DIR}/nina"
  chmod +x "${INSTALL_DIR}/nina"
  say "installed from source → ${INSTALL_DIR}/nina"
}

# ── PATH reminder ─────────────────────────────────────────────────────────────

check_path() {
  case ":${PATH}:" in
    *":${INSTALL_DIR}:"*) ;;
    *)
      blank
      say "${INSTALL_DIR} is not in your PATH. Add it:"
      say "  export PATH=\"\${PATH}:${INSTALL_DIR}\""
      say "  echo 'export PATH=\"\${PATH}:${INSTALL_DIR}\"' >> ~/.bashrc"
      if is_nixos; then
        say "  NixOS: add to environment.sessionVariables in configuration.nix"
      fi
      ;;
  esac
}

# ── closing message ──────────────────────────────────────────────────────────

farewell() {
  printf '\n'
  printf '  thank you!! running nina update occasionally will keep me in tip top shape.\n'
  printf '  get started by running nina hello\n'
  printf '\n'
  printf '  if nina turns out not to be for you, nina goodbye will remove her cleanly.\n'
  printf '\n'
}

# ── main ──────────────────────────────────────────────────────────────────────

banner

if is_nixos; then
  say "NixOS detected"
  if nixos_profile_install; then
    generate_nixos_module
    farewell
    exit 0
  fi
  nixos_shell_build
  generate_nixos_module
  check_path
  farewell
  exit 0
fi

# macOS / generic Linux: download binary, fall back to source build
if install_binary; then
  check_path
  farewell
  exit 0
fi

say "no pre-built binary for ${platform} — falling back to source build"
build_from_source
check_path
farewell