#include "core/anime_db.h"
#include "core/anime.h"
#include "core/filesystem.h"
#include "core/json.h"
#include "core/strings.h"

#include "gui/translate/anilist.h"
#include "gui/translate/anime.h"

#include <QDate>

#include <fstream>

#include <exception>
#include <cstdlib>
#include <iostream>
#include <random>

namespace Anime {

size_t Database::GetTotalAnimeAmount() {
	size_t total = 0;

	for (const auto& [id, anime] : items)
		if (anime.IsInUserList())
			total++;

	return total;
}

size_t Database::GetListsAnimeAmount(ListStatus status) {
	if (status == ListStatus::NotInList)
		return 0;

	size_t total = 0;

	for (const auto& [id, anime] : items)
		if (anime.IsInUserList() && anime.GetUserStatus() == status)
			total++;

	return total;
}

size_t Database::GetTotalEpisodeAmount() {
	size_t total = 0;

	for (const auto& [id, anime] : items)
		if (anime.IsInUserList())
			total += anime.GetUserRewatchedTimes() * anime.GetEpisodes() + anime.GetUserProgress();

	return total;
}

/* Returns the total watched amount in minutes. */
size_t Database::GetTotalWatchedAmount() {
	size_t total = 0;

	for (const auto& [id, anime] : items)
		if (anime.IsInUserList())
			total += anime.GetDuration() * anime.GetUserProgress() +
			         anime.GetEpisodes() * anime.GetDuration() * anime.GetUserRewatchedTimes();

	return total;
}

/* Returns the total planned amount in minutes.
   Note that we should probably limit progress to the
   amount of episodes, as AniList will let you
   set episode counts up to 32768. But that should
   rather be handled elsewhere. */
size_t Database::GetTotalPlannedAmount() {
	size_t total = 0;

	for (const auto& [id, anime] : items)
		if (anime.IsInUserList())
			total += anime.GetDuration() * (anime.GetEpisodes() - anime.GetUserProgress());

	return total;
}

/* In Taiga this is called the mean, but "average" is
   what's primarily used in conversation, at least
   in the U.S. */
double Database::GetAverageScore() {
	double avg = 0;
	size_t amt = 0;

	for (const auto& [id, anime] : items) {
		if (anime.IsInUserList() && anime.GetUserScore()) {
			avg += anime.GetUserScore();
			amt++;
		}
	}
	return avg / amt;
}

double Database::GetScoreDeviation() {
	double squares_sum = 0, avg = GetAverageScore();
	size_t amt = 0;

	for (const auto& [id, anime] : items) {
		if (anime.IsInUserList() && anime.GetUserScore()) {
			squares_sum += std::pow(static_cast<double>(anime.GetUserScore()) - avg, 2);
			amt++;
		}
	}

	return (amt > 0) ? std::sqrt(squares_sum / amt) : 0;
}

/*
 * TODO: separate this from the anime DB,
 * provide *some* sort of normalization
 */
int Database::GetAnimeFromTitle(const std::string& title) {
	if (title.empty())
		return 0;

	std::string title_n(title);
	Strings::NormalizeAnimeTitle(title_n);

	for (const auto& [id, anime] : items) {
		std::vector<std::string> synonyms(anime.GetTitleSynonyms());
		synonyms.push_back(anime.GetUserPreferredTitle());

		for (auto& synonym : synonyms) {
			Strings::NormalizeAnimeTitle(synonym);
			if (synonym == title_n)
				return id;
		}
	}

	return 0;
}

static bool GetListDataAsJSON(const Anime& anime, nlohmann::json& json) {
	if (!anime.IsInUserList())
		return false;

	// clang-format off
	json = {
		{"status", Translate::ToString(anime.GetUserStatus())},
		{"progress", anime.GetUserProgress()},
		{"score", anime.GetUserScore()},
		{"started", anime.GetUserDateStarted().GetAsAniListJson()},
		{"completed", anime.GetUserDateCompleted().GetAsAniListJson()},
		{"private", anime.GetUserIsPrivate()},
		{"rewatched_times", anime.GetUserRewatchedTimes()},
		{"rewatching", anime.GetUserIsRewatching()},
		{"updated", anime.GetUserTimeUpdated()},
		{"notes", anime.GetUserNotes()}
	};
	// clang-format on

	return true;
}

static bool GetAnimeAsJSON(const Anime& anime, nlohmann::json& json) {
	// clang-format off
	json = {
		{"id", anime.GetId()},
		{"synonyms", anime.GetTitleSynonyms()},
		{"episodes", anime.GetEpisodes()},
		{"airing_status", Translate::ToString(anime.GetAiringStatus())},
		{"air_date", anime.GetAirDate().GetAsAniListJson()},
		{"genres", anime.GetGenres()},
		{"producers", anime.GetProducers()},
		{"format", Translate::ToString(anime.GetFormat())},
		// {"season", Translate::ToString(anime.GetSeason())},
		{"audience_score", anime.GetAudienceScore()},
		{"synopsis", anime.GetSynopsis()},
		{"duration", anime.GetDuration()},
		{"poster_url", anime.GetPosterUrl()}
	};
	// clang-format on

	/* now for dynamically-filled stuff */
	for (const auto& lang : TitleLanguages) {
		std::optional<std::string> title = anime.GetTitle(lang);
		if (title.has_value())
			json["title"][Strings::ToLower(Translate::ToString(lang))] = title.value();
	}

	for (const auto& service : Services) {
		std::optional<std::string> id = anime.GetServiceId(service);
		if (id.has_value())
			json["ids"][Strings::ToLower(Translate::ToString(service))] = id.value();
	}

	nlohmann::json user;
	if (GetListDataAsJSON(anime, user))
		json.push_back({"list_data", user});

	return true;
}

bool Database::GetDatabaseAsJSON(nlohmann::json& json) {
	for (const auto& [id, anime] : items) {
		nlohmann::json anime_json = {};
		GetAnimeAsJSON(anime, anime_json);
		json.push_back(anime_json);
	}

	return true;
}

bool Database::SaveDatabaseToDisk() {
	std::filesystem::path db_path = Filesystem::GetAnimeDBPath();
	Filesystem::CreateDirectories(db_path);

	std::ofstream db_file(db_path);
	if (!db_file)
		return false;

	nlohmann::json json = {};
	if (!GetDatabaseAsJSON(json))
		return false;

	db_file << std::setw(4) << json << std::endl;
	return true;
}

static bool ParseAnimeUserInfoJSON(const nlohmann::json& json, Anime& anime) {
	if (!anime.IsInUserList())
		anime.AddToUserList();

	anime.SetUserStatus(Translate::ToListStatus(JSON::GetString<std::string>(json, "/status"_json_pointer, "")));
	anime.SetUserProgress(JSON::GetNumber(json, "/progress"_json_pointer, 0));
	anime.SetUserScore(JSON::GetNumber(json, "/score"_json_pointer, 0));
	anime.SetUserDateStarted(Date(JSON::GetValue(json, "/started"_json_pointer)));
	anime.SetUserDateCompleted(Date(JSON::GetValue(json, "/completed"_json_pointer)));
	anime.SetUserIsPrivate(JSON::GetBoolean(json, "/private"_json_pointer, false));
	anime.SetUserRewatchedTimes(JSON::GetNumber(json, "/rewatched_times"_json_pointer, 0));
	anime.SetUserIsRewatching(JSON::GetBoolean(json, "/rewatching"_json_pointer, false));
	anime.SetUserTimeUpdated(JSON::GetNumber(json, "/updated"_json_pointer, 0));
	anime.SetUserNotes(JSON::GetString<std::string>(json, "/notes"_json_pointer, ""));

	return true;
}

static bool ParseAnimeInfoJSON(const nlohmann::json& json, Database& database) {
	int id = JSON::GetNumber(json, "/id"_json_pointer, 0);
	if (!id)
		return false;

	Anime& anime = database.items[id];

	anime.SetId(id);
	for (const auto& lang : TitleLanguages) {
		nlohmann::json::json_pointer p("/title/" + Strings::ToLower(Translate::ToString(lang)));

		if (json.contains(p) && json[p].is_string())
			anime.SetTitle(lang, json[p].get<std::string>());
	}
	anime.SetTitleSynonyms(JSON::GetArray<std::vector<std::string>>(json, "/synonyms"_json_pointer, {}));
	anime.SetEpisodes(JSON::GetNumber(json, "/episodes"_json_pointer, 0));
	anime.SetAiringStatus(
	    Translate::ToSeriesStatus(JSON::GetString<std::string>(json, "/airing_status"_json_pointer, "")));
	anime.SetAirDate(Date(JSON::GetValue(json, "/air_date"_json_pointer)));
	anime.SetGenres(JSON::GetArray<std::vector<std::string>>(json, "/genres"_json_pointer, {}));
	anime.SetProducers(JSON::GetArray<std::vector<std::string>>(json, "/producers"_json_pointer, {}));
	anime.SetFormat(Translate::ToSeriesFormat(JSON::GetString<std::string>(json, "/format"_json_pointer, "")));
	// anime.SetSeason(Translate::ToSeriesSeason(JSON::GetString<std::string>(json, "/season"_json_pointer, "")));
	anime.SetAudienceScore(JSON::GetNumber(json, "/audience_score"_json_pointer, 0));
	anime.SetSynopsis(JSON::GetString<std::string>(json, "/synopsis"_json_pointer, ""));
	anime.SetDuration(JSON::GetNumber(json, "/duration"_json_pointer, 0));
	anime.SetPosterUrl(JSON::GetString<std::string>(json, "/poster_url"_json_pointer, ""));

	if (json.contains("/list_data"_json_pointer) && json.at("/list_data"_json_pointer).is_object())
		ParseAnimeUserInfoJSON(json.at("/list_data"_json_pointer), anime);

	return true;
}

bool Database::ParseDatabaseJSON(const nlohmann::json& json) {
	for (const auto& anime_json : json)
		ParseAnimeInfoJSON(anime_json, *this);

	return true;
}

bool Database::LoadDatabaseFromDisk() {
	std::filesystem::path db_path = Filesystem::GetAnimeDBPath();
	Filesystem::CreateDirectories(db_path);

	std::ifstream db_file(db_path);
	if (!db_file)
		return false;

	/* When parsing, do NOT throw exceptions */
	nlohmann::json json;
	try {
		json = json.parse(db_file);
	} catch (std::exception const& ex) {
		std::cerr << "[anime/db] Failed to parse JSON! " << ex.what() << std::endl;
		return false;
	}

	if (!ParseDatabaseJSON(json)) /* How */
		return false;

	return true;
}

int Database::GetUnusedId() {
	/* TODO: move these out of here */

	std::random_device rd;
	std::mt19937 gen(rd());
	std::uniform_int_distribution<int> distrib(1, INT_MAX);
	int res;

	do {
		res = distrib(gen);
	} while (items.count(res));

	return res;
}

int Database::LookupServiceId(Service service, const std::string& id_to_find) {
	for (const auto& [id, anime] : items) {
		std::optional<std::string> service_id = anime.GetServiceId(service);
		if (!service_id)
			continue;

		if (service_id == id_to_find)
			return id;
	}

	return 0;
}

int Database::LookupServiceIdOrUnused(Service service, const std::string& id_to_find) {
	int id = LookupServiceId(service, id_to_find);
	if (id)
		return id;

	return GetUnusedId();
}

Database db;

} // namespace Anime