#include <iostream>
#include <iomanip>
#include <fstream>
#include <fmt/core.h>
#include <regex>
#include <string>
#include <iterator>
#include <ctime>
#include "dbc.h"
#include <unistd.h>
#include <stdio.h>
#include <git2/sys/errors.h>
#include <git2.h>
#include <efsw/efsw.hpp>
#include <regex>

using namespace std;
using namespace fmt;

#define BUF_MAX 1024

/*
 * No idea what the semantics of this are.  Will need
 * to research git's dumb terminology to figure out why
 * they have 4 different versions of the path for status.
 */
const char *unfuck_path(const git_status_entry *entry) {
  if(entry->head_to_index != nullptr) {
    if(entry->head_to_index->new_file.path) {
      return entry->head_to_index->new_file.path;
    } else {
      return entry->head_to_index->old_file.path;
    }
  }

  if(entry->index_to_workdir != nullptr) {
    if(entry->index_to_workdir->new_file.path) {
      return entry->index_to_workdir->new_file.path;
    } else {
      return entry->index_to_workdir->old_file.path;
    }
  }

  return nullptr;
}

void add_status(const git_status_entry *entry, unsigned int status_flags, vector<string> &updates) {
  const char *path = unfuck_path(entry);

  if(status_flags & GIT_STATUS_WT_NEW
      || status_flags & GIT_STATUS_INDEX_NEW)
  {
    updates.push_back(string{path});
  }

  if(status_flags & GIT_STATUS_WT_MODIFIED
      || status_flags & GIT_STATUS_INDEX_MODIFIED)
  {
    updates.push_back(string{path});
  }

  // need to confirm this gets the new name
  if(status_flags & GIT_STATUS_WT_RENAMED
      || status_flags & GIT_STATUS_INDEX_RENAMED)
  {
    updates.push_back(string{path});
  }
}

class UpdateListener : public efsw::FileWatchListener {
  public:
    bool changes = false;

    void handleFileAction(efsw::WatchID watchid,
        const std::string& dir,
        const std::string& filename,
        efsw::Action action,
        std::string oldFilename) override
    {
      changes = true;

      switch(action) {
        case efsw::Actions::Add:
          print("ADD {} {} {}\n", dir, filename, oldFilename);
          break;
        case efsw::Actions::Delete:
          print("DEL {} {} {}\n", dir, filename, oldFilename);
          break;
        case efsw::Actions::Modified:
          print("MOD {} {} {}\n", dir, filename, oldFilename);
          break;
        case efsw::Actions::Moved:
          print("MOV {} {} {}\n", dir, filename, oldFilename);
          break;
        default:
          dbc::sentinel("Unknown efsw action.");
      }

    }

    void reset_state() {
      changes = false;
    }
};

void list_git_changes(git_repository* repo) {
  git_status_options opts = GIT_STATUS_OPTIONS_INIT;
  git_status_list *statuses = nullptr;

  //TODO: does this leak?
  int err = git_status_list_new(&statuses, repo, &opts);
  dbc::check(err == 0, git_error_last()->message);
  size_t count = git_status_list_entrycount(statuses);

  vector<string> updates;

  for(size_t i=0; i < count; i++) {
    const git_status_entry *entry = git_status_byindex(statuses, i);
    add_status(entry, entry->status, updates);
  }

  for(string path : updates) {
    print("PATH {}\n", path);
  }
}

void run_build(const char* command) {
  regex err_re("(.*?):([0-9]+):([0-9]+):\\s*(.*?):\\s*(.*)");
  char buffer[BUF_MAX]; // BUF_MAX is a define already?
  smatch err;
  ofstream stats_out;
  stats_out.open("stats.csv", ios::out | ios::app);
  auto t = time(nullptr);
  auto tm = *std::gmtime(&t);

  dbc::check(stats_out.good(), "Error opening stats.csv file.");
  dbc::pre("simple test", [&]() { return stats_out.good(); });

  FILE *build_out = popen(command, "r");
  dbc::check(build_out != nullptr, "Failed to run command.");

  while(fgets(buffer, BUF_MAX, build_out) != nullptr) {
    string line(buffer);  // yeah, that's probably a problem

    print("{}\n", line);
    if(regex_match(line, err, err_re)) {
      string file_name = err[1].str();
      string line = err[2].str();
      string col = err[3].str();
      string type = err[4].str();
      string message = err[5].str();

      stats_out << put_time(&tm, "%FT%TZ");
      stats_out << format(",{},{},{},{},{}\n", file_name, line, col, type, message);
    }
  }

  stats_out.close();
  dbc::post("a post test", [&]() { return !stats_out.is_open(); });
}


int main(int argc, char *argv[])
{
  git_repository* repo = nullptr;

  try {
    dbc::check(argc == 3, "USAGE: watchgit PATH BUILD_CMD");
    const char *git_path = argv[1];
    const char *build_cmd = argv[2];

    print("Using build command: {}", build_cmd);
    efsw::FileWatcher* fileWatcher = new efsw::FileWatcher();
    dbc::check(fileWatcher != nullptr, "Failed to create filewatcher.");

    git_libgit2_init();

    int err = git_repository_open(&repo, git_path);
    dbc::check(err == 0, git_error_last()->message);

    UpdateListener* listener = new UpdateListener();
    dbc::check(listener != nullptr, "Failed to create listener.");

    print("Watching directory {} for changes...\n", git_path);
    efsw::WatchID wid = fileWatcher->addWatch(git_path, listener, true);

    while(true) {
      fileWatcher->watch();

      if(listener->changes) {
        sleep(1);
        list_git_changes(repo);
        listener->reset_state();
        run_build(build_cmd);
      }

      sleep(1);
    }

    git_libgit2_shutdown();
  } catch(dbc::Error &err) {
    print("ERROR: {}\n", err.message);
    if(repo != nullptr) git_repository_free(repo);
    return 1;
  }

  git_libgit2_shutdown();
}