#include "response.h"

#include "base64.h"
#include "file.h"

#include <boost/algorithm/string/predicate.hpp>

#include <functional>
#include <iostream>
#include <string>
#include <unordered_map>

using namespace std::placeholders;

namespace {

class RequestContext
{
private:
 request_type& m_req;
 std::string m_host;
 std::string m_target;
 Server& m_server;
 const Path& m_path;

public:
 RequestContext(request_type& req, Server& server)
  : m_req(req)
  , m_host(req["host"])
  , m_target(req.target())
  , m_server(server)
  , m_path(server.GetConfig().GetPath(server.GetSocket(), m_host, m_target))
 {
 }

 const Path& GetPath() const {return m_path;}
 
 std::string GetPluginName() const {return m_path.params.at("plugin");} // can throw std::out_of_range
 
 std::string GetPluginPath() const {return m_path.requested;}
 
 std::string GetDocRoot() const {return m_path.params.at("target");} // can throw std::out_of_range
 
 std::string GetRelativePath() const { // can throw std::runtime_error
  if (!boost::starts_with(m_target, m_path.requested))
   throw std::runtime_error("Mismatch of target ("s + m_target + ") and plugin path(" + m_path.requested + ")"s);
  if (m_target.size() > m_path.requested.size() && m_target[m_path.requested.size()] == '/')
   return m_target.substr(m_path.requested.size() + 1);
  else
   return m_target.substr(m_path.requested.size());
 }
 
 std::string GetPluginParam(const std::string& key) const {return m_path.params.at(key);} // can throw std::out_of_range
 
 plugin_type GetPlugin() const {return m_server.GetPlugin(m_path.params.at("plugin"));}; // can throw std::out_of_range

 request_type& GetReq() const {return m_req;}

 std::string GetTarget() const {return m_target;}
 
 std::string GetHost() const {return m_host;}

 Server& GetServer() const {return m_server; }
 
 const Socket& GetSocket() const {return m_server.GetSocket(); }
};

std::string extend_index_html(std::string path)
{
 if (path.size() == 0 || path.back() == '/')
  path.append("index.html");
 return path;
}

std::unordered_map<std::string, std::function<std::string(Server&)>> GetServerParamFunctions{
 // following are the supported fields:
 {"version", [](Server& server) { return Server::VersionString; }},
 {"address", [](Server& server) { return server.GetSocket().address; }},
 {"port", [](Server& server) { return server.GetSocket().port; }},
};

std::string GetServerParam(const std::string& key, Server& server)
{
 auto it = GetServerParamFunctions.find(key);
 if (it != GetServerParamFunctions.end())
  return it->second(server);
 
 throw std::runtime_error("Unsupported server param: "s + key);
}

std::unordered_map<std::string, std::function<std::string(RequestContext&)>> GetRequestParamFunctions{
 // following are the supported fields:
 {"authorization", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::authorization]}; }},
 
 {"body", [](RequestContext& req_ctx) { return req_ctx.GetReq().body(); }},

 {"content_length", [](RequestContext& req_ctx) { return std::to_string(req_ctx.GetReq().body().size()); }},

 {"content_type", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::content_type]}; }},

 {"doc_root", [](RequestContext& req_ctx) { return req_ctx.GetDocRoot();}},
 
 {"host", [](RequestContext& req_ctx) { return req_ctx.GetHost();}},

 {"http_accept", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::accept]};}},

 {"http_accept_charset", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::accept_charset]};}},

 {"http_accept_encoding", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::accept_encoding]};}},

 {"http_accept_language", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::accept_language]};}},

 {"http_connection", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::connection]};}},

 {"http_host", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::host]};}},

 {"http_user_agent", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq()[http::field::user_agent]};}},
 
 {"http_version", [](RequestContext& req_ctx) {
   unsigned version {req_ctx.GetReq().version()};
   unsigned major{version / 10};
   unsigned minor{version % 10};
   return "HTTP/"s + std::to_string(major) + "."s + std::to_string(minor);
 }},

 {"location", [](RequestContext& req_ctx) { return req_ctx.GetTarget(); }},
 
 {"method", [](RequestContext& req_ctx) { return std::string{req_ctx.GetReq().method_string()};}},
 
 {"rel_target", [](RequestContext& req_ctx) {return req_ctx.GetRelativePath();}},

 {"target", [](RequestContext& req_ctx) {return req_ctx.GetTarget();}},
};

std::string GetRequestParam(const std::string& key, RequestContext& req_ctx)
{
 // first, look up functions from GetRequestParamFunctions
 {
  auto it = GetRequestParamFunctions.find(key);
  if (it != GetRequestParamFunctions.end())
   return it->second(req_ctx);
 }

 // second, look up plugin parameters
 {
  try {
   return req_ctx.GetPluginParam(key);
  } catch(const std::out_of_range& ex) {
   // not found
  };
 }

 // third, look up req parameters
 // contains: host
 {
  try {
   return std::string{req_ctx.GetReq()[key]};
  } catch(...) {
   // not found
  }
 }

 // otherwise: error
 throw std::runtime_error("Unsupported request param: "s + key);
}

void SetResponseHeader(const std::string& key, const std::string& value, response_type& res)
{
 // following are the supported fields:
 
 if (key == "status") { // HTTP Status, e.g. "200" (OK)
  res.result(unsigned(stoul(value)));
 } else if (key == "server") { // Server name/version string
  res.set(http::field::server, value);
 } else if (key == "content_type") { // e.g. text/html
  res.set(http::field::content_type, value);
 } else if (key == "content_disposition") { // e.g. attachment; ...
  res.set(http::field::content_disposition, value);
 } else if (key == "location") { // e.g. 301 Moved Permanently: new Location
  res.set(http::field::location, value);
 } else
  throw std::runtime_error("Unsupported response field: "s + key);
}

// Return a reasonable mime type based on the extension of a file.
beast::string_view
mime_type(beast::string_view path)
{
    using beast::iequals;
    auto const ext = [&path]
    {
        auto const pos = path.rfind(".");
        if (pos == beast::string_view::npos)
            return beast::string_view{};
        return path.substr(pos);
    }();
    if(iequals(ext, ".htm"))  return "text/html";
    if(iequals(ext, ".html")) return "text/html";
    if(iequals(ext, ".php"))  return "text/html";
    if(iequals(ext, ".css"))  return "text/css";
    if(iequals(ext, ".txt"))  return "text/plain";
    if(iequals(ext, ".js"))   return "application/javascript";
    if(iequals(ext, ".json")) return "application/json";
    if(iequals(ext, ".xml"))  return "application/xml";
    if(iequals(ext, ".swf"))  return "application/x-shockwave-flash";
    if(iequals(ext, ".flv"))  return "video/x-flv";
    if(iequals(ext, ".png"))  return "image/png";
    if(iequals(ext, ".jpe"))  return "image/jpeg";
    if(iequals(ext, ".jpeg")) return "image/jpeg";
    if(iequals(ext, ".jpg"))  return "image/jpeg";
    if(iequals(ext, ".gif"))  return "image/gif";
    if(iequals(ext, ".bmp"))  return "image/bmp";
    if(iequals(ext, ".ico"))  return "image/vnd.microsoft.icon";
    if(iequals(ext, ".tiff")) return "image/tiff";
    if(iequals(ext, ".tif"))  return "image/tiff";
    if(iequals(ext, ".svg"))  return "image/svg+xml";
    if(iequals(ext, ".svgz")) return "image/svg+xml";
    return "application/text";
}

// Used to return errors by generating response page and HTTP status code
response_type HttpStatus(std::string status, std::string message, response_type& res)
{
 res.result(unsigned(stoul(status)));
 res.set(http::field::content_type, "text/html");
 if (res.result_int() == 401)
  res.set(http::field::www_authenticate, "Basic realm=\"Webbox Login\"");
 res.body() = "<html><body><h1>"s + Server::VersionString + " Error</h1><p>"s + status + " "s + message + "</p></body></html>"s;
 res.prepare_payload();

 return res;
}

} // anonymous namespace

response_type generate_response(request_type& req, Server& server)
{
 response_type res{http::status::ok, req.version()};
 res.set(http::field::server, Server::VersionString);
 res.set(http::field::content_type, mime_type(extend_index_html(std::string(req.target()))));
 res.keep_alive(req.keep_alive());

 try {
  RequestContext req_ctx{req, server}; // can throw std::out_of_range

  auto& auth{req_ctx.GetPath().auth};
  if (auth.size() != 0) {
   std::string authorization{req[http::field::authorization]};
   if (authorization.substr(0, 6) != "Basic "s)
    return HttpStatus("401", "Bad Authorization Type", res);
   
   authorization = authorization.substr(6);
   authorization = decode64(authorization);

   size_t pos {authorization.find(':')};
   if (pos == authorization.npos)
    return HttpStatus("401", "Bad Authorization Encoding", res);

   std::string login{authorization.substr(0, pos)};
   std::string password{authorization.substr(pos + 1)};

   auto it {auth.find(login)};
   if (it == auth.end())
    return HttpStatus("401", "Bad Authorization", res);

   if (it->second != password)
    return HttpStatus("401", "Bad Authorization", res); // should be same message as previous one to prevent login guessing
  }

  plugin_type plugin{req_ctx.GetPlugin()};

  auto GetServerParamFunction {std::function<std::string(const std::string& key)>(std::bind(GetServerParam, _1, std::ref(server)))};
  auto GetRequestParamFunction {std::function<std::string(const std::string& key)>(std::bind(GetRequestParam, _1, std::ref(req_ctx)))};
  auto SetResponseHeaderFunction{std::function<void(const std::string& key, const std::string& value)>(std::bind(SetResponseHeader, _1, _2, std::ref(res)))};
  
  std::string res_data { plugin->generate_page(GetServerParamFunction, GetRequestParamFunction, SetResponseHeaderFunction)};
  if (req.method() == http::verb::head) {
   res.content_length(res_data.size());
  } else {
   res.body() = res_data;
   res.prepare_payload();
  }

  return res;
 } catch(const std::out_of_range& ex) {
  return HttpStatus("400", "Bad request: Host "s + std::string{req["host"]} + ":"s + std::string{req.target()} + " unknown"s, res);
 } catch(const std::exception& ex) {
  return HttpStatus("400", "Bad request: "s + std::string{ex.what()}, res);
 }

}