#include "error_handling.h"

#include <errno.h>
#include <stdlib.h> /* for NULL */
#include <stdio.h> /* for fprintf */
#include <assert.h>

static void print_error(int code, const char * action, const char *dirname, const char *basename, const char * constant, const char * description) {
	fprintf(stderr, "Error %s(%i) occured when %s \"%s/%s\": %s\n", constant, code, action, dirname, basename ? basename : "", description);
}

static void default_error(const char ** constant, const char ** description) {
	*constant = "E???";
	*description = "Unknown error";
}

static void describe_opendir_error(int code, const char ** constant, const char ** description) {
	/* http://opengroup.org/onlinepubs/007908799/xsh/opendir.html */
	switch (code) {
	case EACCES: *constant = "EACCES"; *description = "Search permission is denied for the component of the path prefix of dirname or read permission is denied for dirname."; return;
	case ELOOP: *constant = "ELOOP"; *description = "Too many symbolic links were encountered in resolving path."; return;
	case ENOENT: *constant = "ENOENT"; *description = "A component of dirname does not name an existing directory or dirname is an empty string."; return;
	case ENOTDIR: *constant = "ENOTDIR"; *description = "A component of dirname is not a directory."; return;
	case EMFILE: *constant = "EMFILE"; *description = "{OPEN_MAX} file descriptors are currently open in the calling process. "; return;
	case ENAMETOOLONG: *constant = "ENAMETOOLONG"; *description = "Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}."; return;
	case ENFILE: *constant = "ENFILE"; *description = "Too many files are currently open in the system."; return;
	default: default_error(constant, description); return;
	}
	assert(0);
}

static void describe_readdir_error(int code, const char ** constant, const char ** description) {
	/* http://www.opengroup.org/onlinepubs/009695399/functions/readdir.html */
	switch (code) {
	case EOVERFLOW: *constant = "EOVERFLOW"; *description = "One of the values in the structure to be returned cannot be represented correctly."; return;
	case EBADF: *constant = "EBADF"; *description = "The dirp argument does not refer to an open directory stream."; return;
	case ENOENT: *constant = "ENOENT"; *description = "The current position of the directory stream is invalid."; return;
	default: default_error(constant, description); return;
	}
	assert(0);
}

static void describe_stat_error(int code, const char ** constant, const char ** description) {
	/* http://www.opengroup.org/onlinepubs/000095399/functions/stat.html */
	switch (code) {
	case EACCES: *constant = "EACCES"; *description = "Search permission is denied for a component of the path prefix."; return;
	case EIO: *constant = "EIO"; *description = "An error occurred while reading from the file system."; return;
	case ENOENT: *constant = "ENOENT"; *description = "A component of path does not name an existing file or path is an empty string."; return;
	case ENOTDIR: *constant = "ENOTDIR"; *description = "A component of the path prefix is not a directory."; return;
	case ELOOP: *constant = "ELOOP"; *description = "More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument."; return;
	case ENAMETOOLONG: *constant = "ENAMETOOLONG"; *description = "As a result of encountering a symbolic link in resolution of the path argument, the length of the substituted pathname string exceeded {PATH_MAX}."; return;
	case EOVERFLOW: *constant = "EOVERFLOW"; *description = "A value to be stored would overflow one of the members of the stat structure. "; return;
	default: default_error(constant, description); return;
	}
	assert(0);
}

void handle_opendir_error(int code, const char *dirname) {
	const char * constant = NULL;
	const char * description = NULL;
	describe_opendir_error(code, &constant, &description);
	print_error(code, "opening", dirname, NULL, constant, description);
}

void handle_readdir_error(int code, const char *dirname) {
	const char * constant = NULL;
	const char * description = NULL;
	describe_readdir_error(code, &constant, &description);
	print_error(code, "reading", dirname, NULL, constant, description);
}

void handle_stat_error(int code, const char *dirname, const char *basename) {
	const char * constant = NULL;
	const char * description = NULL;
	describe_stat_error(code, &constant, &description);
	print_error(code, "statting", dirname, basename, constant, description);
}