/* 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/>.
 */

#include <err.h>
#include <inttypes.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <unistd.h>

#include "archive.h"
#include "imap.h"

static const char *uidPath(uint32_t uid, const char *type) {
	static char buf[PATH_MAX];
	snprintf(buf, sizeof(buf), "UID/%" PRIu32 ".%s", uid, type);
	return buf;
}

static const char *messagePath(const char *messageID, const char *type) {
	static char buf[PATH_MAX];
	snprintf(buf, sizeof(buf), "message/%s.%s", messageID, type);
	return buf;
}

bool exportFetch(FILE *imap, enum Atom tag, struct List threads) {
	struct List uids = {0};
	listFlatten(&uids, threads);
	for (size_t i = uids.len - 1; i < uids.len; --i) {
		uint32_t uid = dataCheck(uids.ptr[i], Number).number;
		int error = 0
			|| access(uidPath(uid, "atom"), F_OK)
			|| access(uidPath(uid, "html"), F_OK)
			|| access(uidPath(uid, "mbox"), F_OK);
		if (!error) uids.ptr[i] = uids.ptr[--uids.len];
	}
	if (!uids.len) {
		listFree(uids);
		return false;
	}

	fprintf(imap, "%s UID FETCH ", Atoms[tag]);
	for (size_t i = 0; i < uids.len; ++i) {
		fprintf(imap, "%s%" PRIu32, (i ? "," : ""), uids.ptr[i].number);
	}
	fprintf(
		imap,
		" (UID ENVELOPE"
		" BODY[HEADER.FIELDS (" MBOX_HEADERS ")] BODY[TEXT])\r\n"
	);
	return true;
}

void exportData(struct List items) {
	uint32_t uid = 0;
	struct Envelope envelope = {0};
	char *header = NULL;
	char *body = NULL;

	for (size_t i = 0; i + 1 < items.len; i += 2) {
		enum Atom name;
		if (items.ptr[i].type == Atom) {
			name = items.ptr[i].atom;
		} else if (
			items.ptr[i].type == List &&
			items.ptr[i].list.len &&
			items.ptr[i].list.ptr[0].type == Atom
		) {
			name = items.ptr[i].list.ptr[0].atom;
		} else {
			errx(EX_PROTOCOL, "invalid data item name");
		}
		
		struct Data data = items.ptr[i + 1];
		switch (name) {
			break; case AtomBody:
				i--;
			break; case AtomUID:
				uid = dataCheck(data, Number).number;
			break; case AtomEnvelope:
				parseEnvelope(&envelope, dataCheck(data, List).list);
			break; case AtomHeaderFields:
				header = dataCheck(data, String).string;
			break; case AtomText:
				body = dataCheck(data, String).string;
			break; default:;
		}
	}

	if (!uid) errx(EX_PROTOCOL, "missing UID data item");
	if (!envelope.subject) errx(EX_PROTOCOL, "missing ENVELOPE data item");
	if (!header) errx(EX_PROTOCOL, "missing BODY[HEADER.FIELDS] data item");
	if (!body) errx(EX_PROTOCOL, "missing BODY[TEXT] data item");

	const char *path;
	FILE *file;
	int error;

	path = uidPath(uid, "mbox");
	file = fopen(path, "w");
	if (!file) err(EX_CANTCREAT, "%s", path);
	error = mboxFrom(file)
		|| mboxHeader(file, header)
		|| mboxBody(file, body)
		|| fclose(file);
	if (error) err(EX_IOERR, "%s", path);

	const char *dest = messagePath(envelope.messageID, "mbox");
	error = link(path, dest);
	if (error) err(EX_CANTCREAT, "%s", dest);

	path = uidPath(uid, "html");
	file = fopen(path, "w");
	if (!file) err(EX_CANTCREAT, "%s", path);
	error = htmlEnvelope(file, &envelope)
		|| fclose(file);
	if (error) err(EX_IOERR, "%s", path);

	path = uidPath(uid, "atom");
	file = fopen(path, "w");
	if (!file) err(EX_CANTCREAT, "%s", path);
	error = atomEntryHead(file, &envelope)
		|| atomEntryTail(file)
		|| fclose(file);
	if (error) err(EX_IOERR, "%s", path);

	envelopeFree(envelope);
}