#include "parsed-derivations.hh"

#include <absl/strings/str_split.h>

namespace nix {

ParsedDerivation::ParsedDerivation(const Path& drvPath, BasicDerivation& drv)
    : drvPath(drvPath), drv(drv) {
  /* Parse the __json attribute, if any. */
  auto jsonAttr = drv.env.find("__json");
  if (jsonAttr != drv.env.end()) {
    try {
      structuredAttrs = nlohmann::json::parse(jsonAttr->second);
    } catch (std::exception& e) {
      throw Error("cannot process __json attribute of '%s': %s", drvPath,
                  e.what());
    }
  }
}

std::optional<std::string> ParsedDerivation::getStringAttr(
    const std::string& name) const {
  if (structuredAttrs) {
    auto i = structuredAttrs->find(name);
    if (i == structuredAttrs->end()) {
      return {};
    }
    if (!i->is_string()) {
      throw Error("attribute '%s' of derivation '%s' must be a string", name,
                  drvPath);
    }
    return i->get<std::string>();

  } else {
    auto i = drv.env.find(name);
    if (i == drv.env.end()) {
      return {};
    }
    return i->second;
  }
}

bool ParsedDerivation::getBoolAttr(const std::string& name, bool def) const {
  if (structuredAttrs) {
    auto i = structuredAttrs->find(name);
    if (i == structuredAttrs->end()) {
      return def;
    }
    if (!i->is_boolean()) {
      throw Error("attribute '%s' of derivation '%s' must be a Boolean", name,
                  drvPath);
    }
    return i->get<bool>();

  } else {
    auto i = drv.env.find(name);
    if (i == drv.env.end()) {
      return def;
    }
    return i->second == "1";
  }
}

std::optional<Strings> ParsedDerivation::getStringsAttr(
    const std::string& name) const {
  if (structuredAttrs) {
    auto i = structuredAttrs->find(name);
    if (i == structuredAttrs->end()) {
      return {};
    }
    if (!i->is_array()) {
      throw Error("attribute '%s' of derivation '%s' must be a list of strings",
                  name, drvPath);
    }
    Strings res;
    for (const auto& j : *i) {
      if (!j.is_string()) {
        throw Error(
            "attribute '%s' of derivation '%s' must be a list of strings", name,
            drvPath);
      }
      res.push_back(j.get<std::string>());
    }
    return res;

  } else {
    auto i = drv.env.find(name);
    if (i == drv.env.end()) {
      return {};
    }
    return absl::StrSplit(i->second, absl::ByAnyChar(" \t\n\r"));
  }
}

StringSet ParsedDerivation::getRequiredSystemFeatures() const {
  StringSet res;
  for (auto& i : getStringsAttr("requiredSystemFeatures").value_or(Strings())) {
    res.insert(i);
  }
  return res;
}

bool ParsedDerivation::canBuildLocally() const {
  if (drv.platform != settings.thisSystem.get() &&
      (settings.extraPlatforms.get().count(drv.platform) == 0u) &&
      !drv.isBuiltin()) {
    return false;
  }

  for (auto& feature : getRequiredSystemFeatures()) {
    if (settings.systemFeatures.get().count(feature) == 0u) {
      return false;
    }
  }

  return true;
}

bool ParsedDerivation::willBuildLocally() const {
  return getBoolAttr("preferLocalBuild") && canBuildLocally();
}

bool ParsedDerivation::substitutesAllowed() const {
  return getBoolAttr("allowSubstitutes", true);
}

}  // namespace nix