#!/bin/bash

set -euo pipefail

# --- Defaults ---
COPY=true
CLIP_CMD=()

# --- Detect clipboard tool ---
detect_clipboard() {
  # Pick the right tool for the session:
  # wl-copy on Wayland, xclip/xsel on X11. Fall back to whatever exists.
  if [[ "${XDG_SESSION_TYPE:-}" == "wayland" || -n "${WAYLAND_DISPLAY:-}" ]]; then
    if command -v wl-copy &> /dev/null; then
      CLIP_CMD=(wl-copy)
    elif command -v xclip &> /dev/null; then
      CLIP_CMD=(xclip -selection clipboard)
    elif command -v xsel &> /dev/null; then
      CLIP_CMD=(xsel --clipboard --input)
    fi
  else
    if command -v xclip &> /dev/null; then
      CLIP_CMD=(xclip -selection clipboard)
    elif command -v xsel &> /dev/null; then
      CLIP_CMD=(xsel --clipboard --input)
    elif command -v wl-copy &> /dev/null; then
      CLIP_CMD=(wl-copy)
    fi
  fi
}

# --- Help ---
usage() {
  cat << 'EOF'
cat-md — concatenate files as a Markdown code block, copy to clipboard.

Usage:
  cat-md [OPTIONS] [FILE|DIR]...

  Each file is printed as:
      path/to/file:
      ```
      <contents>
      ```

  Directories are expanded non-recursively (all files inside).

Options:
  -n, --no-copy    Print to stdout only, skip clipboard copy
  -h, --help       Show this help and exit

Examples:
  cat-md file1.txt file2.txt
  cat-md src/
  cat-md -n file.txt              # no clipboard
  cat-md -n file.txt | less       # pipe manually

Requirements (one of):
  wl-copy — Wayland clipboard (from wl-clipboard)
  xclip   — X11 clipboard (preferred on X11)
  xsel    — alternative X11 clipboard tool
EOF
  exit 0
}

# --- Parse arguments ---
ARGS=()
while [[ $# -gt 0 ]]; do
  case "$1" in
    -n | --no-copy)
      COPY=false
      shift
      ;;
    -h | --help) usage ;;
    --)
      shift
      ARGS+=("$@")
      break
      ;;
    -*)
      echo "Unknown option: $1" >&2
      echo "Try -h for help." >&2
      exit 1
      ;;
    *)
      ARGS+=("$1")
      shift
      ;;
  esac
done

# --- Validate ---
if [[ ${#ARGS[@]} -eq 0 ]]; then
  echo "Error: no files or directories provided. Try -h for help." >&2
  exit 1
fi

detect_clipboard

if $COPY && [[ ${#CLIP_CMD[@]} -eq 0 ]]; then
  echo "Warning: no clipboard tool found (tried wl-copy, xclip, xsel). Output will go to stdout only." >&2
  COPY=false
fi

# --- Generate output ---
generate() {
  for path in "$@"; do
    if [[ -d "$path" ]]; then
      for file in "$path"/*; do
        if [[ -f "$file" ]]; then
          generate "$file"
        fi
      done
    elif [[ -f "$path" ]]; then
      echo "$path:"
      echo '```'
      cat "$path"
      echo
      echo '```'
      echo
    fi
  done
}

if $COPY; then
  generate "${ARGS[@]}" | "${CLIP_CMD[@]}"
  echo "Copied to clipboard." >&2
else
  generate "${ARGS[@]}"
fi