/*
 * Copyright 2022, Trung Nguyen, trungnt282910@gmail.com
 * All rights reserved. Distributed under the terms of the MIT License.
 */


#include <new>
#include <errno.h>
#include <locale.h>
#include <strings.h>

#include <ErrnoMaintainer.h>

#include "LocaleBackend.h"
#include "LocaleInternal.h"


using BPrivate::Libroot::gGlobalLocaleBackend;
using BPrivate::Libroot::gGlobalLocaleDataBridge;
using BPrivate::Libroot::GetCurrentLocaleInfo;
using BPrivate::Libroot::GetLocalesFromEnvironment;
using BPrivate::Libroot::LocaleBackend;
using BPrivate::Libroot::LocaleBackendData;
using BPrivate::Libroot::LocaleDataBridge;


extern "C" locale_t
duplocale(locale_t l)
{
	LocaleBackendData* locObj = (LocaleBackendData*)l;

	LocaleBackendData* newObj = new (std::nothrow) LocaleBackendData;
	if (newObj == NULL) {
		errno = ENOMEM;
		return (locale_t)0;
	}
	newObj->magic = LOCALE_T_MAGIC;
	newObj->backend = NULL;
	newObj->databridge = NULL;

	LocaleBackend* backend = (l == LC_GLOBAL_LOCALE) ?
		gGlobalLocaleBackend : (LocaleBackend*)locObj->backend;

	if (backend == NULL)
		return (locale_t)newObj;

	// Check if everything is set to "C" or "POSIX",
	// and avoid making a backend.
	const char* localeDescription = backend->SetLocale(LC_ALL, NULL);

	if ((strcasecmp(localeDescription, "POSIX") == 0)
			|| (strcasecmp(localeDescription, "C") == 0)) {
		return (locale_t)newObj;
	}

	LocaleBackend*& newBackend = newObj->backend;
	LocaleDataBridge*& newDataBridge = newObj->databridge;

	status_t status = LocaleBackend::CreateBackend(newBackend);

	if (newBackend == NULL) {
		errno = status;
		delete newObj;
		return (locale_t)0;
	}

	newDataBridge = new (std::nothrow) LocaleDataBridge(false);

	if (newDataBridge == NULL) {
		errno = ENOMEM;
		LocaleBackend::DestroyBackend(newBackend);
		delete newObj;
		return (locale_t)0;
	}

	newBackend->Initialize(newDataBridge);

	// Skipping LC_ALL. Asking for LC_ALL would force the backend
	// to query each other value once, anyway.
	for (int lc = 1; lc <= LC_LAST; ++lc) {
		newBackend->SetLocale(lc, backend->SetLocale(lc, NULL));
	}

	return (locale_t)newObj;
}


extern "C" void
freelocale(locale_t l)
{
	LocaleBackendData* locobj = (LocaleBackendData*)l;

	if (locobj->backend) {
		LocaleBackend::DestroyBackend(locobj->backend);
		LocaleDataBridge* databridge = locobj->databridge;
		delete databridge;
	}
	delete locobj;
}


extern "C" locale_t
newlocale(int category_mask, const char* locale, locale_t base)
{
	if (((category_mask | LC_ALL_MASK) != LC_ALL_MASK) || (locale == NULL)) {
		errno = EINVAL;
		return (locale_t)0;
	}

	bool newObject = false;
	LocaleBackendData* localeObject = (LocaleBackendData*)base;

	if (localeObject == NULL) {
		localeObject = new (std::nothrow) LocaleBackendData;
		if (localeObject == NULL) {
			errno = ENOMEM;
			return (locale_t)0;
		}
		localeObject->magic = LOCALE_T_MAGIC;
		localeObject->backend = NULL;
		localeObject->databridge = NULL;

		newObject = true;
	}

	LocaleBackend*& backend = localeObject->backend;
	LocaleDataBridge*& databridge = localeObject->databridge;

	const char* locales[LC_LAST + 1];
	for (int lc = 0; lc <= LC_LAST; lc++)
		locales[lc] = NULL;

	if (*locale == '\0') {
		if (category_mask == LC_ALL_MASK) {
			GetLocalesFromEnvironment(LC_ALL, locales);
		} else {
			for (int lc = 1; lc <= LC_LAST; ++lc) {
				if (category_mask & (1 << (lc - 1)))
					GetLocalesFromEnvironment(lc, locales);
			}
		}
	} else {
		if (category_mask == LC_ALL_MASK) {
			locales[LC_ALL] = locale;
		}
		for (int lc = 1; lc <= LC_LAST; ++lc) {
			if (category_mask & (1 << (lc - 1)))
				locales[lc] = locale;
		}
	}

	if (backend == NULL) {
		// for any locale other than POSIX/C, we try to activate the ICU
		// backend
		bool needBackend = false;
		for (int lc = 0; lc <= LC_LAST; lc++) {
			if (locales[lc] != NULL && strcasecmp(locales[lc], "POSIX") != 0
					&& strcasecmp(locales[lc], "C") != 0) {
				needBackend = true;
				break;
			}
		}
		if (needBackend) {
			status_t status = LocaleBackend::CreateBackend(backend);
			if (backend == NULL) {
				errno = status;
				if (newObject) {
					delete localeObject;
				}
				return (locale_t)0;
			}
			databridge = new (std::nothrow) LocaleDataBridge(false);
			if (databridge == NULL) {
				errno = ENOMEM;
				LocaleBackend::DestroyBackend(backend);
				if (newObject) {
					delete localeObject;
				}
				return (locale_t)0;
			}
			backend->Initialize(databridge);
		}
	}

	BPrivate::ErrnoMaintainer errnoMaintainer;

	if (backend != NULL) {
		for (int lc = 0; lc <= LC_LAST; lc++) {
			if (locales[lc] != NULL) {
				locale = backend->SetLocale(lc, locales[lc]);
				if (lc == LC_ALL) {
					// skip the rest, LC_ALL overrides
					break;
				}
			}
		}
	}

	return (locale_t)localeObject;
}


extern "C" locale_t
uselocale(locale_t newLoc)
{
	locale_t oldLoc = (locale_t)GetCurrentLocaleInfo();
	if (oldLoc == NULL) {
		oldLoc = LC_GLOBAL_LOCALE;
	}

	if (newLoc != (locale_t)0) {
		// Avoid expensive TLS reads with a local variable.
		locale_t appliedLoc = oldLoc;

		if (newLoc == LC_GLOBAL_LOCALE) {
			appliedLoc = NULL;
		} else {
			if (((LocaleBackendData*)newLoc)->magic != LOCALE_T_MAGIC) {
				errno = EINVAL;
				return (locale_t)0;
			}
			appliedLoc = newLoc;
		}

		SetCurrentLocaleInfo((LocaleBackendData*)appliedLoc);

		if (appliedLoc != NULL) {
			LocaleDataBridge*& databridge = ((LocaleBackendData*)appliedLoc)->databridge;
			// Happens when appliedLoc represents the C locale.
			if (databridge == NULL) {
				LocaleBackend*& backend = ((LocaleBackendData*)appliedLoc)->backend;
				status_t status = LocaleBackend::CreateBackend(backend);
				if (backend == NULL) {
					if (status == B_MISSING_LIBRARY) {
						// This means libroot-addon-icu is not available.
						// Therefore, the global locale is still the C locale
						// and cannot be set to any other locale. Do nothing.
						return oldLoc;
					}
					errno = status;
					return (locale_t)0;
				}

				databridge = new (std::nothrow) LocaleDataBridge(false);
				if (databridge == NULL) {
					LocaleBackend::DestroyBackend(backend);
					errno = ENOMEM;
					return (locale_t)0;
				}

				backend->Initialize(databridge);
			}
			databridge->ApplyToCurrentThread();
		} else {
			gGlobalLocaleDataBridge.ApplyToCurrentThread();
		}
	}

	return oldLoc;
}


extern "C" locale_t
__current_locale_t()
{
	locale_t locale = (locale_t)GetCurrentLocaleInfo();
	if (locale == NULL) {
		static LocaleBackendData global_locale_t;
		global_locale_t.backend = gGlobalLocaleBackend;
		global_locale_t.databridge = &gGlobalLocaleDataBridge;
		return (locale_t)&global_locale_t;
	}

	return locale;
}


extern "C" locale_t
__posix_locale_t()
{
	static LocaleBackendData posix_locale_t;
	posix_locale_t.backend = NULL;
	posix_locale_t.databridge = NULL;
	return &posix_locale_t;
}