#include "LanguageSettings.h"

#include <algorithm>
#include <cstdlib>
#include <iostream>
#include <numeric>
#include <stdexcept>
#include <string>
#include <vector>

#include <fmt/format.h>

#include <libreichwein/stringhelper.h>

#include "env.h"
#include "file.h"

namespace fs = std::filesystem;
using namespace std::string_literals;

LanguageSettings::LanguageSettings():
 // C++
 CXX{env_value("CXX")},
 CXXFLAGS{env_value("CXXFLAGS")},
 LDFLAGS{env_value("LDFLAGS")},
 LDLIBS{env_value("LDLIBS")},
 LIBS{env_value("LIBS")},
 // C
 // CFLAGS

 AR{env_value("AR")}
{
 std::string _default_compiler(find_executable({"g++", "clang++"}));

 if (_default_compiler.empty()) {
  throw std::runtime_error("No default C++ compiler found.");
 }

 // set defaults
 if (CXX.empty()) {
  CXX = _default_compiler;
 }

 if (CXXFLAGS.empty()) {
  CXXFLAGS = "-std=c++17 -Wall -O2";
 }

 if (AR.empty()) {
  AR = "ar";
 }
}

std::string LanguageSettings::getCompileCommand(const std::filesystem::path& target,
                                                const std::filesystem::path& source,
                                                const std::filesystem::path& build,
                                                const std::vector<std::filesystem::path>& includepaths) const
{
 std::string includes{std::accumulate(includepaths.begin(), includepaths.end(), std::string{},
                                      [](const std::string& sum, const fs::path& p){ return sum + " -I" + p.string();})};

 std::string CXXFLAGS_add{is_dynamic_lib(build) ? " -fvisibility=hidden -fPIC"s : ""s};

 // compile: $(CXX) $(CXXFLAGS) -c $< -o $@
 return fmt::format("{}{}{}{} -c {} -o {}",
                    CXX,
                    CXXFLAGS.empty() ? ""s : (" "s + CXXFLAGS),
                    CXXFLAGS_add,
                    includes,
                    source.string(),
                    target.string());
}

std::string LanguageSettings::getLinkCommand(const std::filesystem::path& target,
                                             const std::vector<std::filesystem::path> &inputs,
                                             const std::vector<std::filesystem::path>& link_libs) const
{
 std::string input_string{std::accumulate(inputs.begin(), inputs.end(), std::string{},
                                          [](const std::string& sum, const fs::path& p){
                                            if (is_dynamic_lib(p) || is_dynamic_lib_link(p)) { return sum; }
                                            return sum + " " + p.string();
                                          })};

 if (is_static_lib(target)) {
  // link: $(AR) rcs libxyz.a x.o y.o z.o
  return fmt::format("{} rcs {}{}",
                     AR,
                     target.string(),
                     input_string);
 } else if (is_executable_target(target) || is_dynamic_lib(target)) {
  // dynamic link: -shared -Wl,-soname,libXXX.so.N -o libXXX.so.N.M.O
  std::string LDFLAGS_add{is_dynamic_lib(target) ? fmt::format(" -shared -Wl,-soname,{}",
                                                               soname_shorter(target.string()).string()) : ""s};

  std::string link_libs_string;
  for (const auto& i: link_libs) {
   if (is_static_lib(i.string())) {
    input_string += " " + i.string();
   } else if (is_dynamic_lib(i.string()) || is_dynamic_lib_link(i.string())) {
    input_string += " -L" + lib_path(i).string() + " -l" + dynamic_lib_name(i);
   } else { // link external dynamic lib, e.g. "fmt"
    link_libs_string += " -l" + i.string();
   }
  }

  // link: $(CXX) $(LDFLAGS) $^ $(LDLIBS) $(LIBS) -o $@
  return fmt::format("{}{}{}{}{}{}{} -o {}",
                     CXX,
                     LDFLAGS.empty() ? ""s : (" "s + LDFLAGS),
                     LDFLAGS_add,
                     input_string,
                     LDLIBS.empty() ? ""s : (" "s + LDLIBS),
                     LIBS.empty() ? ""s : (" "s + LIBS),
                     link_libs_string,
                     target.string());
 } else if (is_dynamic_lib_link(target)) {
  // special case for dynamic libs: add links
  if (inputs.size() != 1) {
   throw std::runtime_error("For symlink "s + target.string() + ", can link to exactly one file, found "s + std::to_string(inputs.size()));
  }
  return fmt::format("ln -sf {} {}", inputs[0].filename().string(), target.string());
 } else {
  throw std::runtime_error("No implementation for target type: "s + target.string());
 }
}

std::string LanguageSettings::getDepCommand(const std::filesystem::path& target, const std::filesystem::path &source) const
{
 // g++ -MM -MF <depfile> -c <cppfile>
 return fmt::format("{} -MM -MF {} -c {}", CXX, target.string(), source.string());
}

// TODO:
// variables:
//  CC
//  CFLAGS
//  ARFLAGS
//  AS
//  ASFLAGS