#!/usr/bin/env ruby
# GPT-5 Action-Oriented Agent - pure stdlib

require "net/http"
require "json"
require "uri"
require "reline"

API_KEY = ENV["OPENAI_API_KEY"] or abort("Set OPENAI_API_KEY")
MODEL   = "gpt-5"

# Tools GPT-5 can use
TOOLS = [
  {
    type: "function",
    function: {
      name: "read_file",
      description: "Read contents of a file",
      parameters: {
        type: "object",
        properties: { path: { type: "string" } },
        required: ["path"]
      }
    }
  },
  {
    type: "function",
    function: {
      name: "write_file",
      description: "Write contents to a file",
      parameters: {
        type: "object",
        properties: { path: { type: "string" }, content: { type: "string" } },
        required: ["path","content"]
      }
    }
  },
  {
    type: "function",
    function: {
      name: "run_command",
      description: "Run a shell command and return output",
      parameters: {
        type: "object",
        properties: { command: { type: "string" } },
        required: ["command"]
      }
    }
  }
]

# Execute tools
def run_tool(name, args)
  case name
  when "read_file"
    begin
      { content: File.read(args["path"]) }
    rescue => e
      { error: e.message }
    end
  when "write_file"
    begin
      File.write(args["path"], args["content"])
      { status: "ok" }
    rescue => e
      { error: e.message }
    end
  when "run_command"
    begin
      { output: `#{args["command"]}`.strip }
    rescue => e
      { error: e.message }
    end
  else
    { error: "unknown tool #{name}" }
  end
end

# Call OpenAI
def openai_chat(messages, tools)
  uri = URI("https://api.openai.com/v1/chat/completions")
  req = Net::HTTP::Post.new(uri)
  req["Authorization"] = "Bearer #{API_KEY}"
  req["Content-Type"] = "application/json"

  req.body = {
    model: MODEL,
    messages: messages,
    tools: tools,
    tool_choice: "auto"
  }.to_json

  res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |h| h.request(req) }
  raise "HTTP #{res.code}: #{res.body}" unless res.is_a?(Net::HTTPSuccess)
  JSON.parse(res.body)
end

# Conversation with bias-for-action
messages = [
  { role: "system", content: <<~MSG
      You are a reasoning coding and system agent. Prioritize taking practical actions whenever possible.
      Use read_file, write_file, and run_command proactively to achieve user goals.
      Explain your reasoning briefly in content. Avoid unnecessary delays; act whenever sufficient info is available.
  MSG
  }
]

puts ">> Type instructions (or 'exit')"

loop do
  input = Reline.readline("User> ", true)&.strip
  break if input.nil? || input.downcase == "exit"
  messages << { role: "user", content: input }

  loop do
    resp = openai_chat(messages, TOOLS)
    msg = resp.dig("choices", 0, "message")
    messages << msg

    # Print reasoning content immediately
    if msg["content"] && !msg["content"].empty?
      puts "\nAssistant> #{msg['content']}"
    end

    # Execute any tool calls
    if msg["tool_calls"]
      msg["tool_calls"].each do |call|
        name = call.dig("function","name")
        args = JSON.parse(call.dig("function","arguments"))
        result = run_tool(name, args)
        messages << { role: "tool", tool_call_id: call["id"], content: JSON.dump(result) }
      end
      next # continue reasoning on tool results
    end

    break # no tool calls left, turn is done
  end
end