differ

#!/usr/bin/env bash

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
# shellcheck source=lib/cli_common.sh
source "${SCRIPT_DIR}/lib/cli_common.sh"

TOOL_NAME="differ"
CONF_DIR="$(cli_conf_dir "${TOOL_NAME}")"
CONF_PATH="${CONF_DIR}/differ.json"

help() {
  cli_print_help "${TOOL_NAME}" "quickly compare two texts" \
    "f1 f2|Diff two files or URLs" \
    "f1|Diff file against stored main" \
    "store <f1>|Store a main file to diff against" \
    "conf|Print the configuration file" \
    "-h, --help|Show this help"
  printf "Input files must be fully qualified paths or URLs.\n"
  printf "Configuration file: %s\n" "${CONF_PATH}"
}

resolve_file() {
  local path="$1"
  local tmp_name="$2"

  if [[ -f "${path}" ]]; then
    echo "${path}"
    return
  fi

  if [[ "${path}" =~ ^https?:// ]]; then
    printf "Downloading %s\n" "${path}" >&2
    curl -s "${path}" > "/tmp/${tmp_name}"
    echo "/tmp/${tmp_name}"
    return
  fi

  printf "%s does not exist\n" "${path}" >&2
  exit 1
}

do_diff() {
  local file1 file2
  file1="$(resolve_file "$1" "differ1")"
  file2="$(resolve_file "$2" "differ2")"
  git diff --no-index --color-words "${file1}" "${file2}" || true
}

diff_with_main() {
  local main
  main="$(jq -r '.main // empty' "${CONF_PATH}")"
  if [[ -z "${main}" ]]; then
    printf "No main file stored, please store a main file first\n" >&2
    help
    exit 1
  fi
  do_diff "${main}" "$1"
}

# Handle help
case "${1:-}" in
  -h|--help|help) help; exit 0 ;;
esac

# Ensure config exists (auto-init)
if [[ ! -f "${CONF_PATH}" ]]; then
  cli_ensure_conf "${TOOL_NAME}" "differ.json:{}"
  printf "Configuration file generated at %s\n" "${CONF_PATH}"
fi

case "${1:-}" in
  store)
    if [[ -z "${2:-}" ]]; then
      printf "Error: no file given to store\n" >&2
      help
      exit 1
    fi
    file="$2"
    if [[ -f "$2" ]]; then
      file="$(realpath "$2")"
    elif [[ ! "$2" =~ ^https?:// ]]; then
      printf "%s does not exist\n" "$2" >&2
      exit 1
    fi
    jq --arg f "${file}" '.main = $f' "${CONF_PATH}" > "${CONF_PATH}.tmp"
    mv "${CONF_PATH}.tmp" "${CONF_PATH}"
    printf "Main file stored as %s\n" "$2"
    ;;
  conf)
    cat "${CONF_PATH}"
    ;;
  "")
    printf "Error: no file given to diff against\n" >&2
    help
    exit 1
    ;;
  *)
    if [[ -z "${2:-}" ]]; then
      printf "Comparing with %s\n" "$(jq -r '.main' "${CONF_PATH}")"
      diff_with_main "$1"
    else
      do_diff "$1" "$2"
    fi
    ;;
esac