//
// Created by m on 7/27/17.
//

#include <algorithm>

#include "json_helper.hpp"
#include "layers.hpp"
#include "util.hpp"

namespace wm {

using json = nlohmann::json;

surface_id_to_layer::surface_id_to_layer(nlohmann::json const &j) {
   // DB(j);
   if (j["type"] == "range") {
      this->id_min = get<int>(j["first_surface_id"]);
      this->id_max = get<int>(j["last_surface_id"]);
   } else {
      this->id_min = this->id_max = get<int>(j["surface_id"]);
   }
   this->name = j["name"].get<std::string>();
   this->layer_id = get<int>(j["layer_id"]);
}

struct result<struct surface_id_to_layer_map> to_surface_id_to_layer_map(
   nlohmann::json const &j) {
   DB(j);
   try {
      surface_id_to_layer_map stl{};
      auto m = j["mappings"];
      stl.layers.reserve(m.size());
      std::transform(
         std::cbegin(m), std::cend(m),
         std::inserter(stl.mapping, stl.mapping.end()),
         [&stl](nlohmann::json const &j) {
            auto k = surface_id_to_layer(j);
            stl.layers.push_back(unsigned(k.layer_id));
            return k;
         });
      // XXX need to sort layers?
      for (auto i : stl.mapping) {
         if (i.name.empty()) {
            return Err<struct surface_id_to_layer_map>(
               "Found mapping w/o name");
         }
         if (i.layer_id == -1 || i.id_min == -1 || i.id_max == -1) {
            return Err<struct surface_id_to_layer_map>(
               "Found invalid/unset IDs in mapping");
         }
      }

      // Check lookup
      auto jtests = j.value("tests", json());

      if (! jtests.empty()) {
         DB("Embedded tests...");
         std::vector<std::pair<int, int>> tests;
         tests.reserve(jtests.size());
         std::transform(std::cbegin(jtests), std::cend(jtests),
                        std::back_inserter(tests), [](json const &j) {
                    return std::make_pair(get<int>(j["surface_id"]),
                                          get<int>(j["expect_layer_id"]));
                 });

         for (auto sid : tests) {
            int lid = stl.get_layer_for_surface(sid.first).value_or(-1);
            DB("this=" << sid.first << ", that=" << lid
                       << ", expect=" << sid.second);
            if (lid != sid.second) {
               return Err<surface_id_to_layer_map>(
                       "ID Map embedded test failed!");
            }
         }
      }

      return Ok(stl);
   } catch (std::exception &e) {
      return Err<struct surface_id_to_layer_map>(e.what());
   }
}

// Helper to allow std::lower_bound with a int key only
inline bool
   operator<(struct surface_id_to_layer const &a, int b) {
   return a.id_max < b;
}

optional<int> surface_id_to_layer_map::get_layer_for_surface(int surface_id) {
   auto i = std::lower_bound(std::cbegin(this->mapping),
                             std::cend(this->mapping), surface_id);

   if (i != this->mapping.end()) {
      // std::less only checks for surface_id_to_layer::id_max, so check
      // that we are actually inside of an interval here.
      if (i->id_min <= surface_id) {
         return optional<int>(i->layer_id);
      }
   }

   return nullopt;
}

}  // namespace wm