#pragma once

#include "shader.h"
#include "utils/resource_utils.h"
#include <QDebug>
#include <QFile>
#include <QFileInfo>
#include <QString>
#include <QStringList>
#include <memory>
#include <unordered_map>
#include <utility>

namespace Render::GL {

class ShaderCache {
public:
  auto load(const QString &name, const QString &vert_path,
            const QString &frag_path) -> Shader * {
    auto it = m_named.find(name);
    if (it != m_named.end()) {
      return it->second.get();
    }
    const QString resolved_vert =
        Utils::Resources::resolveResourcePath(vert_path);
    const QString resolved_frag =
        Utils::Resources::resolveResourcePath(frag_path);
    auto sh = std::make_unique<Shader>();
    if (!sh->load_from_files(resolved_vert, resolved_frag)) {
      qWarning() << "ShaderCache: Failed to load shader" << name;
      return nullptr;
    }
    Shader *raw = sh.get();
    m_named.emplace(name, std::move(sh));
    return raw;
  }

  auto get(const QString &name) const -> Shader * {
    auto it = m_named.find(name);
    return (it != m_named.end()) ? it->second.get() : nullptr;
  }

  auto get_or_load(const QString &vert_path,
                   const QString &frag_path) -> Shader * {
    const QString resolved_vert =
        Utils::Resources::resolveResourcePath(vert_path);
    const QString resolved_frag =
        Utils::Resources::resolveResourcePath(frag_path);
    auto key = resolved_vert + "|" + resolved_frag;
    auto it = m_byPath.find(key);
    if (it != m_byPath.end()) {
      return it->second.get();
    }
    auto sh = std::make_unique<Shader>();
    if (!sh->load_from_files(resolved_vert, resolved_frag)) {
      qWarning() << "ShaderCache: Failed to load shader from paths:"
                 << resolved_vert << "," << resolved_frag;
      return nullptr;
    }
    Shader *raw = sh.get();
    m_byPath.emplace(std::move(key), std::move(sh));
    return raw;
  }

  void initialize_defaults() {
    static const QString kShaderBase = QStringLiteral(":/assets/shaders/");
    auto resolve = [](const QString &path) {
      return Utils::Resources::resolveResourcePath(path);
    };

    const QString basicVert =
        resolve(kShaderBase + QStringLiteral("basic.vert"));
    const QString basicFrag =
        resolve(kShaderBase + QStringLiteral("basic.frag"));
    const QString gridFrag = resolve(kShaderBase + QStringLiteral("grid.frag"));
    load(QStringLiteral("basic"), basicVert, basicFrag);
    load(QStringLiteral("grid"), basicVert, gridFrag);
    const QString cylVert =
        resolve(kShaderBase + QStringLiteral("cylinder_instanced.vert"));
    const QString cylFrag =
        resolve(kShaderBase + QStringLiteral("cylinder_instanced.frag"));
    load(QStringLiteral("cylinder_instanced"), cylVert, cylFrag);

    const QString primVert =
        resolve(kShaderBase + QStringLiteral("primitive_instanced.vert"));
    const QString primFrag =
        resolve(kShaderBase + QStringLiteral("primitive_instanced.frag"));
    load(QStringLiteral("primitive_instanced"), primVert, primFrag);

    const QString fogVert =
        resolve(kShaderBase + QStringLiteral("fog_instanced.vert"));
    const QString fogFrag =
        resolve(kShaderBase + QStringLiteral("fog_instanced.frag"));
    load(QStringLiteral("fog_instanced"), fogVert, fogFrag);
    const QString grassVert =
        resolve(kShaderBase + QStringLiteral("grass_instanced.vert"));
    const QString grassFrag =
        resolve(kShaderBase + QStringLiteral("grass_instanced.frag"));
    load(QStringLiteral("grass_instanced"), grassVert, grassFrag);

    const QString stoneVert =
        resolve(kShaderBase + QStringLiteral("stone_instanced.vert"));
    const QString stoneFrag =
        resolve(kShaderBase + QStringLiteral("stone_instanced.frag"));
    load(QStringLiteral("stone_instanced"), stoneVert, stoneFrag);

    const QString plantVert =
        resolve(kShaderBase + QStringLiteral("plant_instanced.vert"));
    const QString plantFrag =
        resolve(kShaderBase + QStringLiteral("plant_instanced.frag"));
    load(QStringLiteral("plant_instanced"), plantVert, plantFrag);

    const QString pineVert =
        resolve(kShaderBase + QStringLiteral("pine_instanced.vert"));
    const QString pineFrag =
        resolve(kShaderBase + QStringLiteral("pine_instanced.frag"));
    load(QStringLiteral("pine_instanced"), pineVert, pineFrag);
    const QString oliveVert =
        resolve(kShaderBase + QStringLiteral("olive_instanced.vert"));
    const QString oliveFrag =
        resolve(kShaderBase + QStringLiteral("olive_instanced.frag"));
    load(QStringLiteral("olive_instanced"), oliveVert, oliveFrag);

    const QString firecampVert =
        resolve(kShaderBase + QStringLiteral("firecamp.vert"));
    const QString firecampFrag =
        resolve(kShaderBase + QStringLiteral("firecamp.frag"));
    load(QStringLiteral("firecamp"), firecampVert, firecampFrag);

    const QString groundVert =
        resolve(kShaderBase + QStringLiteral("ground_plane.vert"));
    const QString groundFrag =
        resolve(kShaderBase + QStringLiteral("ground_plane.frag"));
    load(QStringLiteral("ground_plane"), groundVert, groundFrag);

    const QString terrainVert =
        resolve(kShaderBase + QStringLiteral("terrain_chunk.vert"));
    const QString terrainFrag =
        resolve(kShaderBase + QStringLiteral("terrain_chunk.frag"));
    load(QStringLiteral("terrain_chunk"), terrainVert, terrainFrag);

    const QString riverVert =
        resolve(kShaderBase + QStringLiteral("river.vert"));
    const QString riverFrag =
        resolve(kShaderBase + QStringLiteral("river.frag"));
    load(QStringLiteral("river"), riverVert, riverFrag);

    const QString riverbankVert =
        resolve(kShaderBase + QStringLiteral("riverbank.vert"));
    const QString riverbankFrag =
        resolve(kShaderBase + QStringLiteral("riverbank.frag"));
    load(QStringLiteral("riverbank"), riverbankVert, riverbankFrag);

    const QString roadVert = resolve(kShaderBase + QStringLiteral("road.vert"));
    const QString roadFrag = resolve(kShaderBase + QStringLiteral("road.frag"));
    load(QStringLiteral("road"), roadVert, roadFrag);

    const QString bridgeVert =
        resolve(kShaderBase + QStringLiteral("bridge.vert"));
    const QString bridgeFrag =
        resolve(kShaderBase + QStringLiteral("bridge.frag"));
    load(QStringLiteral("bridge"), bridgeVert, bridgeFrag);

    const QString troopShadowVert =
        resolve(kShaderBase + QStringLiteral("troop_shadow.vert"));
    const QString troopShadowFrag =
        resolve(kShaderBase + QStringLiteral("troop_shadow.frag"));
    load(QStringLiteral("troop_shadow"), troopShadowVert, troopShadowFrag);

    const QString bannerVert =
        resolve(kShaderBase + QStringLiteral("banner.vert"));
    const QString bannerFrag =
        resolve(kShaderBase + QStringLiteral("banner.frag"));
    load(QStringLiteral("banner"), bannerVert, bannerFrag);

    const QString healingBeamVert =
        resolve(kShaderBase + QStringLiteral("healing_beam.vert"));
    const QString healingBeamFrag =
        resolve(kShaderBase + QStringLiteral("healing_beam.frag"));
    load(QStringLiteral("healing_beam"), healingBeamVert, healingBeamFrag);

    const QString healingAuraVert =
        resolve(kShaderBase + QStringLiteral("healing_aura.vert"));
    const QString healingAuraFrag =
        resolve(kShaderBase + QStringLiteral("healing_aura.frag"));
    load(QStringLiteral("healing_aura"), healingAuraVert, healingAuraFrag);

    load(QStringLiteral("combat_dust"),
         resolve(kShaderBase + QStringLiteral("combat_dust.vert")),
         resolve(kShaderBase + QStringLiteral("combat_dust.frag")));

    load(QStringLiteral("mode_indicator"),
         resolve(kShaderBase + QStringLiteral("mode_indicator.vert")),
         resolve(kShaderBase + QStringLiteral("mode_indicator.frag")));

    const auto loadBaseShader = [&](const QString &name) {
      const QString vert =
          resolve(kShaderBase + name + QStringLiteral(".vert"));
      const QString frag =
          resolve(kShaderBase + name + QStringLiteral(".frag"));
      load(name, vert, frag);
      return std::pair<QString, QString>{vert, frag};
    };

    const auto [archerVert, archerFrag] =
        loadBaseShader(QStringLiteral("archer"));
    const auto [swordsmanVert, swordsmanFrag] =
        loadBaseShader(QStringLiteral("swordsman"));
    const auto [horseKnightVert, horseKnightFrag] =
        loadBaseShader(QStringLiteral("horse_swordsman"));
    const auto [spearmanVert, spearmanFrag] =
        loadBaseShader(QStringLiteral("spearman"));
    const auto [healerVert, healerFrag] =
        loadBaseShader(QStringLiteral("healer"));

    const QStringList nationVariants = {QStringLiteral("roman_republic"),
                                        QStringLiteral("carthage")};

    auto resourceExists = [](const QString &path) -> bool {
      QFileInfo const info(path);
      return info.exists();
    };

    auto loadVariant = [&](const QString &base_key, const QString &baseVertPath,
                           const QString &baseFragPath) {
      for (const QString &nation : nationVariants) {
        const QString shaderName = base_key + QStringLiteral("_") + nation;
        const QString variantVertRes = kShaderBase + base_key +
                                       QStringLiteral("_") + nation +
                                       QStringLiteral(".vert");
        const QString variantFragRes = kShaderBase + base_key +
                                       QStringLiteral("_") + nation +
                                       QStringLiteral(".frag");

        QString resolvedVert = resolve(variantVertRes);
        if (!resourceExists(resolvedVert)) {
          resolvedVert = baseVertPath;
        }

        QString resolvedFrag = resolve(variantFragRes);
        if (!resourceExists(resolvedFrag)) {
          resolvedFrag = baseFragPath;
        }

        load(shaderName, resolvedVert, resolvedFrag);
      }
    };

    loadVariant(QStringLiteral("archer"), archerVert, archerFrag);
    loadVariant(QStringLiteral("spearman"), spearmanVert, spearmanFrag);
    loadVariant(QStringLiteral("swordsman"), swordsmanVert, swordsmanFrag);
    loadVariant(QStringLiteral("horse_swordsman"), horseKnightVert,
                horseKnightFrag);
    loadVariant(QStringLiteral("healer"), healerVert, healerFrag);
    loadVariant(QStringLiteral("horse_archer"), horseKnightVert,
                horseKnightFrag);
    loadVariant(QStringLiteral("horse_spearman"), horseKnightVert,
                horseKnightFrag);
  }

  void clear() {
    m_named.clear();
    m_byPath.clear();
    m_cache.clear();
  }

private:
  std::unordered_map<QString, std::unique_ptr<Shader>> m_byPath;

  std::unordered_map<QString, std::unique_ptr<Shader>> m_named;

  std::unordered_map<QString, std::unique_ptr<Shader>> m_cache;
};

} // namespace Render::GL