-- An example HTTP server written in Konjac
module Rum.Request
  struct [
    method: String;
    path: String;
    headers: Map(String, String);
  ]
end

module Rum.Response
  struct [
    statusCode: Int64 = 200;
    headers: Map(String, String) = {};
    body: Binary = Binary { };
  ]
  
  export function encode(response : Rum.Response) : Binary
    
    reasonPhrase : String = case response.statusCode
      when 200, do: "OK"
      when 201, do: "Created"
      when 301, do: "Moved Permanently"
      when 400, do: "Bad Request"
      when 404, do: "Not Found"
      when 500, do: "Internal Server Error"
      else do: "Unknown"
    end
    
    statusLine : String = "HTTP/1.1 " + Int64.toString(response.statusCode) + " " + reasonPhrase + "\r\n"

    updatedHeaders : Map(String, String) = if Map.hasKey(response.headers, "Content-Length")
      response.headers
    else
      Map.put(response.headers, "Content-Length", String.fromInt(Binary.length(response.body)))
    end
    
    headersString : String = updatedHeaders
      |> Map.toList()  
      |> Array.map(function(pair : {String, String}) do
        pair.key + ": " + pair.value + "\r\n"
      end)
      |> String.join()
      |> String.concatenate("\r\n\r\n")
      
    statusLine
    |> String.concatenate(headersString)
    |> Binary.fromString()
    |> Binary.concatenate(response.body)
  end
end

module Rum.Context
  struct [
    request: Rum.Request;
    response: Rum.Response;
  ]
end

behaviour Rum.Handler
  abstract function call(handler : Rum.Handler, context : Rum.Context) : Rum.Context
end

module Rum.Server
  struct [
    host: String;
    port: UInt16;
    handlers: Array(Rum.Handler);
  ]

  function handleClient(server : Rum.Server, client : TCP.Client) : Nil
    data : Binary = TCP.receive(client)

    [headerSection, messageBody] = 
      data
      |> Binary.toString()
      |> String.split("\r\n\r\n")

    [startLine, ...unprocessedHeaders]
      headerSection
      |> String.split("\r\n")

    headers =
      unprocessedHeaders 
      |> Array.map(function(header : String) do
        [key, value] = String.split(header)
        
        {key: value}
      end)
      |> Map.zip()
      
    [method, path, "HTTP/1.1"] = startLine |> String.split(" ") |> String.stripSuffix()

    context = 
      Rum.Context { 
        request: Rum.Request { 
          method: method,
          path: path,
          headers: headers 
        }, 
        response: Rum.Response { }
      }

    updatedContext = 
      server.handlers
      |> Array.reduce(function(handler : Rum.Handler, accumulator : Rum.Context) do 
        Rum.handler.call(handler, accumulator)
      end)
      
    encodedResponse = Rum.Response.encode(updatedContext.response)

    TCP.send(client, encodedResponse)
  end

  export function bind(server : Rum.Server) : Rum.Response
    loop do
      client : TCP.Client? = TCP.accept(server.host, server.port)
      
      if client do
        Process.spawn do
          handleClient(server, client)
        end
      else
        Process.killSelf()
      end
    end
  end
end

module Rum.Application
  export function main(arguments : Array(String)) : Nil
    server = Rum.Server { host: "127.0.0.1", port: 8080 }

    supervisor = 
      Supervisor {
        strategy: "OneForOne",
        maximumRestarts: 5,
        restartWindow: 10
      }

    process = Process.spawn do
      Rum.Server.bind(server)
    end

    child = Child {
      id: "worker",
      process: process,
      restart: "Transiet",
      maxRestarts: 3,
      restartWindow: 5
    }
    
    Supervisor.addChild(supervisor, child)
  end
end