#!/usr/bin/env bash
# x-sha256sum-matcher
#
# Check if two files are the same
#
# Ismo Vuorinen <https://github.com/ivuorinen> 2023
# MIT License

set -euo pipefail

# ENV Variables
: "${VERBOSE:=0}" # VERBOSE=1 x-sha256sum-matcher file1 file2

# Return sha256sum for file
# $1 - filename (string)
get_sha256sum()
{
  sha256sum "$1" | head -c 64
}

# Print message if VERBOSE is enabled
# $1 - message (string)
msg()
{
  [[ "$VERBOSE" -eq 1 ]] && echo "$1"
}

# Print error message and exit
# $1 - error message (string)
error()
{
  msg "(!) ERROR: $1"
  exit 1
}

# Validate input arguments
validate_inputs()
{
  if [ "$#" -ne 2 ]; then
    echo "Usage: $0 file1 file2"
    exit 1
  fi
}

# Check if file exists
# $1 - filename (string)
check_file_exists()
{
  local filename=$1
  if [ ! -f "$filename" ]; then
    error "File does not exist: $filename"
  fi
}

# Main function
main()
{
  local file_1=$1
  local file_2=$2

  validate_inputs "$file_1" "$file_2"
  check_file_exists "$file_1"
  check_file_exists "$file_2"

  local file_1_hash
  local file_2_hash

  file_1_hash=$(get_sha256sum "$file_1")
  file_2_hash=$(get_sha256sum "$file_2")

  if [ "$file_1_hash" != "$file_2_hash" ]; then
    error "Files do not match"
  else
    msg "(*) Success: Files do match"
  fi
}

main "$@"