pathsmith

#!/usr/bin/env ruby
# pathsmith: Generate shell scripts to set PATH for various shells
# Usage: pathsmith [-v|--verbose] [-p|--paths PATHFILE] SHELL
# Outputs shell code to stdout. Source it in your shell config.

require 'optparse'
require 'etc'
require 'shellwords'

def main
  config = parse_options
  shell_target = (ARGV.shift || 'sh').downcase
  validate_target(shell_target)

  raw_lines = read_paths_file(config[:paths_file], config[:verbose])
  all_paths = merge_with_env_path(raw_lines)
  final_paths = process_paths(all_paths, config[:verbose])

  output_result(shell_target, final_paths)
end

def parse_options
  config = {
    paths_file: File.expand_path('~/.config/pathsmith.conf'),
    verbose: false
  }

  OptionParser.new do |opts|
    opts.banner = "Usage: pathsmith [-v|--verbose] [-p|--paths PATHFILE] SHELL"
    opts.on('-v', '--verbose', 'Enable verbose output') { config[:verbose] = true }
    opts.on('-pPATH', '--paths=PATH', 'Specify paths file') { |p| config[:paths_file] = File.expand_path(p) }
    opts.on('-h', '--help', 'Show help') do
      puts opts
      exit 0
    end
  end.parse!(ARGV)

  config
end

def validate_target(shell_target)
  supported_targets = %w[sh ash bash zsh fish nu nushell pwsh powershell list]
  unless supported_targets.include?(shell_target)
    warn "[pathsmith] Unsupported target: #{shell_target}. Supported: #{supported_targets.join(', ')}"
    exit 2
  end
end

def expand_path(str)
  # Expand environment variables, tilde, and resolve relative paths
  File.expand_path(str.gsub(/\$(\w+|\{\w+\})/) { |m| ENV[m[1..-1].gsub(/[{}]/, '')] || "" })
end

def read_paths_file(paths_file, verbose)
  File.readlines(paths_file, chomp: true) || []
rescue Errno::ENOENT
  warn "[pathsmith] Paths file not found: #{paths_file}" if verbose
  []
rescue Errno::EACCES
  warn "[pathsmith] Permission denied for paths file: #{paths_file}"
  exit 1
rescue StandardError => e
  warn "[pathsmith] Error reading paths file: #{e.message}"
  exit 1
end

def merge_with_env_path(raw_lines)
  (raw_lines + (ENV['PATH'] || '').split(File::PATH_SEPARATOR)).freeze
end

def process_paths(all_paths, verbose)
  all_paths
    .map(&:strip)
    .reject { |line| line.empty? || line.start_with?('#') }
    .map(&method(:expand_path))
    .select { |path| absolute_path?(path) }
    .select { |path| validate_directory(path, verbose) }
    .uniq
    .freeze
end

def absolute_path?(path)
  path.start_with?('/') || path =~ /^[A-Za-z]:[\/\\]/
end

def validate_directory(path, verbose)
  exists = File.directory?(path)
  if verbose
    message = exists ? "Added: #{path}" : "Skipped (not a directory): #{path}"
    warn "[pathsmith] #{message}"
  end
  exists
end

def output_result(shell_target, final_paths)
  case shell_target
  when 'list'
    final_paths.each { |p| puts p }
  when 'fish'
    puts "set -gx PATH #{final_paths.map { |p| Shellwords.escape(p) }.join(' ')};"
  when 'nu', 'nushell', 'pwsh', 'powershell'
    puts "$env:PATH = \"#{final_paths.join(';')}\""
  else
    puts "export PATH=#{final_paths.map { |p| Shellwords.escape(p) }.join(File::PATH_SEPARATOR)}"
  end
end

main if __FILE__ == $0