#!/usr/bin/env ruby

require 'json'
require 'securerandom'
require 'shellwords'
require 'net/http'
require 'uri'

class OllamaClient
  def initialize(options = {})
    @model = options[:model] || 'llama3.2'
    @uri = URI("http://127.0.0.1:11434/api/chat")
  end

  def chat(messages, &block)
    Net::HTTP.start(@uri.hostname, @uri.port, http_options) do |http|
      http.request(build_request(messages)) do |response|
        if response.is_a?(Net::HTTPSuccess)
          response.read_body(&block)
        else
          raise "Ollama API error: #{response.code} #{response.message}"
        end
      end
    end
  end

  private

  def http_options
    {
      open_timeout: 10,
      read_timeout: 3600,
      use_ssl: @uri.scheme == "https"
    }
  end

  def build_request(messages)
    Net::HTTP::Post.new(@uri.path).tap do |request|
      request["Accept"] = "application/json"
      request["Content-Type"] = "application/json"
      request["User-Agent"] = "ruby-cli/1.0.0"
      request.body = build_payload(messages).to_json
    end
  end

  def build_payload(messages)
    {
      messages: messages,
      model: @model,
      stream: true,
      keep_alive: "5m",
      options: { temperature: 0.1 }
    }
  end
end

class ShellParser
  SHELL_OPERATORS = %w[|| && ;; |& <( <<< >> >& <& & ; ( ) | < >].freeze
  SHELL_META_CHARS = '|&;()<> \t'.freeze

  def initialize
    @operator_pattern = build_operator_pattern
  end
  
  def parse_shell_command(command, env = {})
    tokens = tokenize(command)
    return { command: nil, args: [] } if tokens.empty?
    
    processed_tokens = substitute_variables(tokens, env)
    
    {
      command: processed_tokens.first,
      args: processed_tokens[1..-1] || []
    }
  end
  
  private
  
  def build_operator_pattern
    escaped = SHELL_OPERATORS.map { |op| Regexp.escape(op) }
    Regexp.new("^(#{escaped.join('|')})$")
  end
  
  def tokenize(command)
    tokens = []
    current_token = ''
    in_quotes = false
    quote_char = nil
    escaped = false
    
    command.each_char.with_index do |char, i|
      if escaped
        current_token += char
        escaped = false
      elsif in_quotes
        if char == quote_char
          in_quotes = false
          quote_char = nil
        else
          current_token += char
        end
      elsif char == '\\'
        escaped = true
      elsif char == '"' || char == "'"
        in_quotes = true
        quote_char = char
      elsif char.match?(/\s/)
        if !current_token.empty?
          tokens << current_token
          current_token = ''
        end
      else
        current_token += char
      end
    end
    
    tokens << current_token unless current_token.empty?
    tokens
  end
  
  def substitute_variables(tokens, env)
    tokens.map do |token|
      token.gsub(/\$\{([^}]+)\}|\$([A-Za-z_][A-Za-z0-9_]*)/) do
        var_name = $1 || $2
        env[var_name] || ENV[var_name] || ''
      end
    end
  end
end

class HttpClient
  def initialize(options = {})
    @timeout = options[:timeout] || 30
    @retries = options[:retries] || 3
  end
  
  def get(url)
    uri = URI(url)
    
    @retries.times do |attempt|
      begin
        response = Net::HTTP.start(uri.hostname, uri.port, 
                                   use_ssl: uri.scheme == 'https',
                                   read_timeout: @timeout) do |http|
          http.get(uri.path.empty? ? '/' : uri.path)
        end
        
        return {
          status: response.code.to_i,
          data: parse_response_body(response),
          headers: response.to_hash
        }
      rescue => error
        raise error if attempt == @retries - 1
        sleep(2 ** attempt)
      end
    end
  end
  
  private
  
  def parse_response_body(response)
    content_type = response['content-type']
    
    if content_type&.include?('application/json')
      JSON.parse(response.body)
    else
      response.body
    end
  rescue JSON::ParserError
    response.body
  end
end

class CLIApplication
  BUILTIN_COMMANDS = %w[cd pwd echo export set history help version exit quit ask].freeze
  
  def initialize(options = {})
    @options = {
      debug: options[:debug] || false,
      timeout: options[:timeout] || 30000
    }.merge(options)
    
    @shell_parser = ShellParser.new
    @http_client = HttpClient.new
    @ollama_client = OllamaClient.new(options)
    @active_commands = {}
    @command_history = []
    @conversation_history = []
    @environment = detect_runtime
    @current_dir = Dir.pwd
    
    init
  end
  
  def execute_command(command, context = {})
    command_id = SecureRandom.uuid
    start_time = Time.now
    
    begin
      parsed = @shell_parser.parse_shell_command(command, context[:env] || {})
      
      raise "Invalid command: empty or malformed" if parsed[:command].nil? || parsed[:command].empty?
      
      # Check if it's a builtin command
      if builtin_command?(parsed[:command])
        result = execute_builtin_command(parsed, context)
      # Check if it's an executable system command
      elsif system_command_exists?(parsed[:command])
        @active_commands[command_id] = {
          command: parsed[:command],
          args: parsed[:args],
          start_time: start_time
        }
        result = execute_external_command(parsed, context)
      else
        # Command not found, send to AI
        return execute_ask(command.split)
      end
      
      add_to_history(command, result)
      result
      
    rescue => error
      handle_error(error, "command-execution", { command: command, command_id: command_id })
      raise
    ensure
      @active_commands.delete(command_id)
    end
  end
  
  def start_repl
    puts "CLI Application Starting..." if @options[:debug]
    puts "Runtime: #{@environment[:name]} #{@environment[:version]}" if @options[:debug]
    puts "Type 'help' for available commands, 'exit' to quit.\n\n"
    
    loop do
      print "#{File.basename(@current_dir)} > "
      command = gets&.strip
      
      break if command.nil?
      next if command.empty?
      
      begin
        result = execute_command(command)
        puts result[:stdout] unless result[:stdout].empty?
        $stderr.puts result[:stderr] unless result[:stderr].empty?
        
        break if result[:should_exit]
      rescue => error
        puts "Error: #{error.message}"
      end
    end
  end
  
  private
  
  def init
    log_startup_info if @options[:debug]
  end
  
  def detect_runtime
    {
      name: "Ruby",
      version: RUBY_VERSION,
      platform: RUBY_PLATFORM
    }
  end
  
  def log_startup_info
    puts "Ruby CLI Application v1.0.0"
    puts "Runtime: #{@environment[:name]} #{@environment[:version]}"
    puts "Platform: #{@environment[:platform]}"
  end
  
  def builtin_command?(command)
    BUILTIN_COMMANDS.include?(command)
  end
  
  def execute_builtin_command(parsed, context)
    command = parsed[:command]
    args = parsed[:args]
    
    case command
    when 'echo'
      execute_echo(args)
    when 'pwd'
      execute_pwd
    when 'cd'
      execute_cd(args.first)
    when 'export'
      execute_export(args, context)
    when 'set'
      execute_set(args, context)
    when 'history'
      execute_history(args)
    when 'help'
      execute_help
    when 'version'
      execute_version
    when 'exit', 'quit'
      execute_exit(args)
    when 'ask'
      execute_ask(args)
    else
      raise "Unknown builtin command: #{command}"
    end
  end
  
  def execute_external_command(parsed, context)
    command = parsed[:command]
    args = parsed[:args]
    
    case command
    when 'ls', 'dir'
      execute_ls(args)
    when 'cat', 'type'
      execute_cat(args)
    when 'curl', 'wget'
      execute_curl(args)
    else
      execute_system_command(command, args)
    end
  end
  
  def execute_echo(args)
    output = args.join(' ')
    {
      exit_code: 0,
      stdout: output,
      stderr: ""
    }
  end
  
  def execute_pwd
    {
      exit_code: 0,
      stdout: @current_dir,
      stderr: ""
    }
  end
  
  def execute_cd(path)
    path = ENV['HOME'] if path.nil? || path == '~'
    
    begin
      expanded_path = File.expand_path(path, @current_dir)
      
      if Dir.exist?(expanded_path)
        @current_dir = expanded_path
        {
          exit_code: 0,
          stdout: "",
          stderr: "",
          cwd: @current_dir
        }
      else
        {
          exit_code: 1,
          stdout: "",
          stderr: "cd: #{path}: No such file or directory"
        }
      end
    rescue => error
      {
        exit_code: 1,
        stdout: "",
        stderr: "cd: #{error.message}"
      }
    end
  end
  
  def execute_export(args, context)
    if args.empty?
      vars = ENV.map { |key, value| "#{key}=#{value}" }.join("\n")
      return {
        exit_code: 0,
        stdout: vars,
        stderr: ""
      }
    end
    
    args.each do |arg|
      key, value = arg.split('=', 2)
      if key && !value.nil?
        ENV[key] = value
        context[:env] ||= {}
        context[:env][key] = value
      end
    end
    
    {
      exit_code: 0,
      stdout: "",
      stderr: ""
    }
  end
  
  def execute_set(args, context)
    execute_export(args, context)
  end
  
  def execute_history(args)
    count = args.first ? args.first.to_i : @command_history.length
    history = @command_history.last(count)
                             .each_with_index
                             .map { |entry, index| "#{index + 1}  #{entry[:command]}" }
                             .join("\n")
    
    {
      exit_code: 0,
      stdout: history,
      stderr: ""
    }
  end
  
  def execute_help
    help_text = <<~HELP
      CLI Application Help
      
      Builtin Commands:
        cd [path]        Change directory
        pwd              Print working directory  
        echo [args]      Print arguments
        export [var]     Set environment variable
        set [var]        Set shell variable
        history [n]      Show command history
        ask [question]   Ask AI assistant a question
        help             Show this help information
        version          Show version information
        exit/quit        Exit the application
      
      External Commands:
        System commands are executed directly.
        
      AI Assistant:
        Any input that isn't a valid command is sent to AI automatically.
        You can also use 'ask' command explicitly.
        
      Examples:
        cd /home/user
        echo "Hello World"
        ls -la
        what time is it?
        ask "What is Ruby?"
        how do I install ruby?
    HELP
    
    {
      exit_code: 0,
      stdout: help_text.strip,
      stderr: ""
    }
  end
  
  def execute_version
    version_text = <<~VERSION
      Ruby CLI Application v1.0.0
      Runtime: #{@environment[:name]} #{@environment[:version]}
      Platform: #{@environment[:platform]}
    VERSION
    
    {
      exit_code: 0,
      stdout: version_text.strip,
      stderr: ""
    }
  end
  
  def execute_ask(args)
    if args.empty?
      return {
        exit_code: 1,
        stdout: "",
        stderr: "ask: missing question"
      }
    end
    
    question = args.join(' ')
    
    @conversation_history << {
      role: "user",
      content: question
    }
    
    begin
      response_content = ""
      print "🤖 "
      
      @ollama_client.chat(@conversation_history) do |chunk|
        chunk.split("\n").each do |line|
          next if line.strip.empty?
          
          begin
            data = JSON.parse(line)
            if data['message'] && data['message']['content']
              content = data['message']['content']
              print content
              response_content += content
            end
          rescue JSON::ParserError
          end
        end
      end
      
      puts
      
      @conversation_history << {
        role: "assistant", 
        content: response_content
      }
      
      {
        exit_code: 0,
        stdout: response_content,
        stderr: ""
      }
    rescue => error
      {
        exit_code: 1,
        stdout: "",
        stderr: "ask: #{error.message}"
      }
    end
  end
  
  def execute_exit(args)
    exit_code = args.first ? args.first.to_i : 0
    
    {
      exit_code: exit_code,
      stdout: "Goodbye!",
      stderr: "",
      should_exit: true
    }
  end
  
  def execute_ls(args)
    begin
      path = args.empty? ? @current_dir : File.expand_path(args.first, @current_dir)
      
      unless Dir.exist?(path)
        return {
          exit_code: 1,
          stdout: "",
          stderr: "ls: #{args.first}: No such file or directory"
        }
      end
      
      entries = Dir.entries(path)
      
      if args.include?('-a') || args.include?('-la') || args.include?('-al')
        files = entries
      else
        files = entries.reject { |f| f.start_with?('.') }
      end
      
      if args.include?('-l') || args.include?('-la') || args.include?('-al')
        output = files.map do |file|
          filepath = File.join(path, file)
          stat = File.lstat(filepath)
          
          permissions = format_permissions(stat.mode)
          size = stat.size
          mtime = stat.mtime.strftime('%b %d %H:%M')
          
          "#{permissions} #{stat.nlink} #{stat.uid} #{stat.gid} #{size} #{mtime} #{file}"
        end.join("\n")
      else
        output = files.join("\n")
      end
      
      {
        exit_code: 0,
        stdout: output,
        stderr: ""
      }
    rescue => error
      {
        exit_code: 1,
        stdout: "",
        stderr: "ls: #{error.message}"
      }
    end
  end
  
  def execute_cat(args)
    if args.empty?
      return {
        exit_code: 1,
        stdout: "",
        stderr: "cat: missing file operand"
      }
    end
    
    output = ""
    stderr = ""
    exit_code = 0
    
    args.each do |filename|
      filepath = File.expand_path(filename, @current_dir)
      
      begin
        content = File.read(filepath)
        output += content
      rescue => error
        stderr += "cat: #{filename}: #{error.message}\n"
        exit_code = 1
      end
    end
    
    {
      exit_code: exit_code,
      stdout: output,
      stderr: stderr.chomp
    }
  end
  
  def execute_curl(args)
    if args.empty?
      return {
        exit_code: 1,
        stdout: "",
        stderr: "curl: missing URL"
      }
    end
    
    url = args.last
    
    begin
      response = @http_client.get(url)
      {
        exit_code: 0,
        stdout: response[:data].is_a?(Hash) ? JSON.pretty_generate(response[:data]) : response[:data].to_s,
        stderr: ""
      }
    rescue => error
      {
        exit_code: 1,
        stdout: "",
        stderr: "curl: #{error.message}"
      }
    end
  end
  
  def execute_system_command(command, args)
    begin
      full_command = Shellwords.join([command] + args)
      output = `cd #{Shellwords.escape(@current_dir)} && #{full_command} 2>&1`
      exit_code = $?.exitstatus
      
      {
        exit_code: exit_code,
        stdout: output,
        stderr: ""
      }
    rescue => error
      {
        exit_code: 1,
        stdout: "",
        stderr: "#{command}: #{error.message}"
      }
    end
  end
  
  private
  
  def system_command_exists?(command)
    # Check if command exists in PATH
    ENV['PATH'].split(':').any? do |path|
      File.executable?(File.join(path, command))
    end
  end
  
  def format_permissions(mode)
    perms = ""
    
    perms += File.directory?(mode) ? "d" : "-"
    
    perms += (mode & 0o400 != 0) ? "r" : "-"
    perms += (mode & 0o200 != 0) ? "w" : "-"
    perms += (mode & 0o100 != 0) ? "x" : "-"
    
    perms += (mode & 0o040 != 0) ? "r" : "-"
    perms += (mode & 0o020 != 0) ? "w" : "-"
    perms += (mode & 0o010 != 0) ? "x" : "-"
    
    perms += (mode & 0o004 != 0) ? "r" : "-"
    perms += (mode & 0o002 != 0) ? "w" : "-"
    perms += (mode & 0o001 != 0) ? "x" : "-"
    
    perms
  end
  
  def add_to_history(command, result)
    @command_history << {
      command: command,
      timestamp: Time.now,
      exit_code: result[:exit_code],
      duration: result[:duration]
    }
    
    @command_history = @command_history.last(500) if @command_history.length > 1000
  end
  
  def handle_error(error, context, metadata = {})
    error_info = {
      message: error.message,
      backtrace: error.backtrace&.first(5),
      context: context,
      timestamp: Time.now
    }.merge(metadata)
    
    if @options[:debug]
      puts "CLI Error: #{error_info}"
    end
  end
end

def create_cli(options = {})
  CLIApplication.new(options)
end

def main
  options = parse_options(ARGV.dup)
  
  if options[:command]
    app = create_cli(options)
    
    begin
      result = app.execute_command(options[:command])
      puts result[:stdout]
      $stderr.puts result[:stderr] unless result[:stderr].empty?
      exit(result[:exit_code])
    rescue => error
      $stderr.puts "Command failed: #{error.message}"
      exit(1)
    end
  else
    app = create_cli(options)
    app.start_repl
  end
end

def parse_options(argv)
  options = {
    debug: false,
    host: nil,
    model: nil,
    command: nil
  }
  
  while arg = argv.shift
    case arg
    when '--debug'
      options[:debug] = true
    when '--host'
      options[:host] = argv.shift
    when '--model'
      options[:model] = argv.shift
    when '--help'
      show_usage
      exit(0)
    else
      options[:command] = ([arg] + argv).join(' ')
      break
    end
  end
  
  options
end

def show_usage
  puts <<~USAGE
    Usage: #{$0} [options] [command]
    
    Options:
      --debug          Enable debug mode
      --host HOST      Set Ollama host (default: localhost:11434)
      --model MODEL    Set Ollama model (default: llama3.2)
      --help           Show this help
    
    Examples:
      #{$0}                              # Start interactive REPL
      #{$0} --host localhost:11434       # Connect to specific Ollama instance
      #{$0} --model qwen2.5              # Use different model
      #{$0} echo "Hello World"           # Execute single command
      #{$0} ask "What is Ruby?"          # Ask AI question directly
  USAGE
end

if __FILE__ == $0
  main
end