#include "Symlink.h"
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
/* #include <stdio.h> */

#define JNI_COMMIT_AND_RELEASE 0

#define FAILURE_GET_PATH 1
#define FAILURE_LSTAT 2
#define FAILURE_NEW_BUF 3
#define FAILURE_GET_BUF 4
#define FAILURE_READLINK 5
#define FAILURE_SIZE_MISMATCH 6
#define FAILURE_MALLOC_BUF 7
#define FAILURE_SYMLINK 8

jint packStatus(jint failure, jint status) {
	if (failure == 0) return status ;
	else return -((failure * 65536) + status) ;
}

JNIEXPORT jint JNICALL Java_Symlink_readlink(JNIEnv *env, jclass cl, jstring pathStr, jobjectArray bufHolder) {
	int failure ; // 0 is success
	int status = 0 ;
	const jbyte *path = (*env)->GetStringUTFChars(env, pathStr, NULL) ;
	if (path != NULL) {
		struct stat statbuf ;
		int lstatOk = lstat(path, &statbuf) ;
		if (lstatOk == 0) {
			int size = statbuf.st_size ;
			jbyteArray bufArr = (*env)->NewByteArray(env, size) ;
			if (bufArr != NULL) {
				jbyte *buf = (*env)->GetByteArrayElements(env, bufArr, NULL) ;
				if (buf != NULL) {
					int bufReleaseMode ;
					int actualsize = readlink(path, buf, size) ;
					if (actualsize > -1) {
						if (actualsize == size) {
							(*env)->SetObjectArrayElement(env, bufHolder, 0, bufArr) ;
							failure = 0 ; // success!
							status = size ;
							bufReleaseMode = JNI_COMMIT_AND_RELEASE ;
						}
						else {
							failure = FAILURE_SIZE_MISMATCH ;
							bufReleaseMode = JNI_ABORT ;
						}
					}
					else {
						failure = FAILURE_READLINK ;
						status = errno ;
						bufReleaseMode = JNI_ABORT ;
					}
					(*env)->ReleaseByteArrayElements(env, bufArr, buf, bufReleaseMode) ;
				}
				else {
					failure = FAILURE_GET_BUF ; // OutOfMemoryError will already have been thrown
				}
			}
			else {
				failure = FAILURE_NEW_BUF ; // OutOfMemoryError will already have been thrown
			}
		}
		else {
			failure = FAILURE_LSTAT ;
			status = errno ;
		}
		(*env)->ReleaseStringUTFChars(env, pathStr, NULL) ;
	}
	else {
		failure = FAILURE_GET_PATH ; // OutOfMemoryError will already have been thrown
	}
	return packStatus(failure, status) ;
}

JNIEXPORT jint JNICALL Java_Symlink_symlink(JNIEnv *env, jclass cl, jstring pathStr, jbyteArray bufArr) {
	int failure ; // 0 is success
	int status = 0 ;
	const jbyte *path = (*env)->GetStringUTFChars(env, pathStr, NULL) ;
	if (path != NULL) {
		int size = (*env)->GetArrayLength(env, bufArr) ;
		jbyte *buf = malloc((size + 1)) ;
		if (buf != NULL) {
			(*env)->GetByteArrayRegion(env, bufArr, 0, size, buf) ;
			buf[size] = (jbyte)0 ;
			int symlinkOk = symlink(buf, path) ;
			if (symlinkOk == 0) {
				failure = 0 ; // success!
			}
			else {
				failure = FAILURE_SYMLINK ;
				status = errno ;
			}
			free(buf) ;
		}
		else {
			failure = FAILURE_MALLOC_BUF ;
		}
		(*env)->ReleaseStringUTFChars(env, pathStr, NULL) ;
	}
	else {
		failure = FAILURE_GET_PATH ; // OutOfMemoryError will already have been thrown
	}
	return packStatus(failure, status) ;
}