/* Copyright (C) 2020  C. McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifndef IMAP_H
#define IMAP_H

#include <err.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>

#define ENUM_ATOM \
	X(AtomNil, "NIL") \
	X(AtomOk, "OK") \
	X(AtomNo, "NO") \
	X(AtomBad, "BAD") \
	X(AtomPreauth, "PREAUTH") \
	X(AtomBye, "BYE") \
	X(AtomAlert, "ALERT") \
	X(AtomBadCharset, "BADCHARSET") \
	X(AtomCapability, "CAPABILITY") \
	X(AtomParse, "PARSE") \
	X(AtomPermanentFlags, "PERMANENTFLAGS") \
	X(AtomReadOnly, "READ-ONLY") \
	X(AtomReadWrite, "READ-WRITE") \
	X(AtomTryCreate, "TRYCREATE") \
	X(AtomUIDNext, "UIDNEXT") \
	X(AtomUIDValidity, "UIDVALIDITY") \
	X(AtomUnseen, "UNSEEN") \
	X(AtomList, "LIST") \
	X(AtomLSub, "LSUB") \
	X(AtomStatus, "STATUS") \
	X(AtomSearch, "SEARCH") \
	X(AtomFlags, "FLAGS") \
	X(AtomExists, "EXISTS") \
	X(AtomRecent, "RECENT") \
	X(AtomExpunge, "EXPUNGE") \
	X(AtomFetch, "FETCH") \
	X(AtomThread, "THREAD") \
	X(AtomUID, "UID") \
	X(AtomEnvelope, "ENVELOPE") \
	X(AtomBodyStructure, "BODYSTRUCTURE") \
	X(AtomBody, "BODY") \
	X(AtomHeaderFields, "HEADER.FIELDS") \
	X(AtomText, "TEXT") \
	X(AtomUntagged, "*")

enum Atom {
#define X(id, str) id,
	ENUM_ATOM
#undef X
	AtomCap = 1024,
};

extern const char *Atoms[AtomCap];

static inline enum Atom atomn(const char *str, size_t len) {
	enum Atom i;
	for (i = 0; i < AtomCap; ++i) {
		if (!Atoms[i]) break;
		if (strlen(Atoms[i]) != len) continue;
		if (!strncasecmp(Atoms[i], str, len)) return i;
	}
	if (i == AtomCap) errx(EX_SOFTWARE, "atom capacity exceeded");
	Atoms[i] = strndup(str, len);
	if (!Atoms[i]) err(EX_OSERR, "strndup");
	return i;
}

static inline enum Atom atom(const char *str) {
	return atomn(str, strlen(str));
}

struct Data {
	enum Type {
		Atom,
		Number,
		String,
		List,
	} type;
	union {
		enum Atom atom;
		uint32_t number;
		char *string;
		struct List {
			size_t cap;
			size_t len;
			struct Data *ptr;
		} list;
	};
};

static inline struct Data dataCheck(struct Data data, enum Type type) {
	const char *Types[] = { "atom", "number", "string", "list" };
	if (data.type != type) {
		errx(
			EX_PROTOCOL, "expected %s, found %s",
			Types[type], Types[data.type]
		);
	}
	return data;
}

static inline void listPush(struct List *list, struct Data data) {
	if (list->len == list->cap) {
		list->cap = (list->cap ? list->cap * 2 : 4);
		list->ptr = realloc(list->ptr, sizeof(*list->ptr) * list->cap);
		if (!list->ptr) err(EX_OSERR, "realloc");
	}
	list->ptr[list->len++] = data;
}

static inline void listFlatten(struct List *flat, struct List nested) {
	for (size_t i = 0; i < nested.len; ++i) {
		if (nested.ptr[i].type == List) {
			listFlatten(flat, nested.ptr[i].list);
		} else {
			listPush(flat, nested.ptr[i]);
		}
	}
}

static inline void dataFree(struct Data data);

static inline void listFree(struct List list) {
	for (size_t i = 0; i < list.len; ++i) {
		dataFree(list.ptr[i]);
	}
	free(list.ptr);
}

static inline void dataFree(struct Data data) {
	if (data.type == String) free(data.string);
	if (data.type == List) listFree(data.list);
}

struct Resp {
	enum Atom tag;
	uint32_t number;
	enum Atom resp;
	struct List code;
	struct List data;
	const char *text;
};

static inline void respFree(struct Resp resp) {
	listFree(resp.code);
	listFree(resp.data);
}

extern bool imapVerbose;
FILE *imapOpen(const char *host, const char *port);
struct Resp imapResp(FILE *imap);

#endif /* IMAP_H */