/* 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"

bool exportFetch(FILE *imap, enum Atom tag, struct List threads) {
	struct List uids = {0};
	listFlatten(&uids, threads);
	char path[PATH_MAX];
	for (size_t i = uids.len - 1; i < uids.len; --i) {
		uint32_t uid = dataCheck(uids.ptr[i], Number).number;
		int error = 0
			|| access(pathUID(path, uid, "atom"), F_OK)
			|| access(pathUID(path, uid, "html"), F_OK)
			|| access(pathUID(path, 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 BODYSTRUCTURE"
		" BODY[HEADER.FIELDS (" MBOX_HEADERS ")] BODY[TEXT])\r\n"
	);
	return true;
}

static void exportEnvelope(uint32_t uid, const struct Envelope *envelope) {
	int error;
	FILE *file;
	char path[PATH_MAX];

	file = fopen(pathUID(path, uid, "html"), "w");
	if (!file) err(EX_CANTCREAT, "%s", path);
	error = 0
		|| htmlMessageHead(file, envelope)
		|| htmlMessageTail(file)
		|| fclose(file);
	if (error) err(EX_IOERR, "%s", path);

	file = fopen(pathUID(path, uid, "atom"), "w");
	if (!file) err(EX_CANTCREAT, "%s", path);
	error = 0
		|| atomEntryOpen(file, envelope)
		|| atomEntryClose(file)
		|| fclose(file);
	if (error) err(EX_IOERR, "%s", path);
}

static void exportRaw(
	uint32_t uid, const struct Envelope *envelope,
	const char *header, const char *body
) {
	char src[PATH_MAX];
	FILE *file = fopen(pathUID(src, uid, "mbox"), "w");
	if (!file) err(EX_CANTCREAT, "%s", src);
	int error = 0
		|| mboxFrom(file)
		|| mboxHeader(file, header)
		|| mboxBody(file, body)
		|| fclose(file);
	if (error) err(EX_IOERR, "%s", src);

	char dst[PATH_MAX];
	pathMessage(dst, envelope->messageID, "mbox");
	unlink(dst);
	error = link(src, dst);
	if (error) err(EX_CANTCREAT, "%s", dst);
}

static void exportBodyPart(
	uint32_t uid, const struct BodyPart *structure,
	const struct BodyPart *part, const char *content
) {
}

bool exportData(FILE *imap, enum Atom tag, struct List items) {
	uint32_t uid = 0;
	struct Envelope envelope = {0};
	struct BodyPart structure = {0};
	const char *header = NULL;
	const 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 AtomBodyStructure:
				parseBodyPart(&structure, 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");

	exportRaw(uid, &envelope, header, body);
	exportEnvelope(uid, &envelope);

	if (structure.multipart) {
		// TODO: FETCH each body part.
	} else {
		exportBodyPart(uid, &structure, &structure, body);
	}

	envelopeFree(envelope);
	bodyPartFree(structure);
	return false;
}