/* Copyright (C) 2019-2021  June 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/>.
 *
 * Additional permission under GNU GPL version 3 section 7:
 *
 * If you modify this Program, or any covered work, by linking or
 * combining it with OpenSSL (or a modified version of that library),
 * containing parts covered by the terms of the OpenSSL License and the
 * original SSLeay license, the licensors of this Program grant you
 * additional permission to convey the resulting work. Corresponding
 * Source for a non-source form of such a combination shall include the
 * source code for the parts of OpenSSL used as well as that of the
 * covered work.
 */

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

#ifdef DECLARE_RPP
#define RPP_STDIN 1
char * readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags);
#else
#include <readpassphrase.h>
#endif

#include "imap.h"

#define FETCH_HEADERS \
	"Date Subject From Sender Reply-To To Cc Bcc " \
	"Message-Id In-Reply-To References " \
	"MIME-Version Content-Type Content-Disposition Content-Transfer-Encoding"

static void mboxrd(char *header, char *body) {
	printf("From mboxrd@z Thu Jan  1 00:00:00 1970\n");
	for (char *crlf; (crlf = strstr(header, "\r\n")); header = &crlf[2]) {
		*crlf = '\0';
		printf("%s\n", header);
	}
	if (!body) return;
	for (char *crlf; (crlf = strstr(body, "\r\n")); body = &crlf[2]) {
		*crlf = '\0';
		char *from = body;
		while (*from == '>') from++;
		if (!strncmp(from, "From ", 5)) {
			printf(">%s\n", body);
		} else {
			printf("%s\n", body);
		}
	}
	printf("\n");
}

static void printNums(FILE *file, struct List nums) {
	for (size_t i = 0; i < nums.len; ++i) {
		uint32_t num = dataCheck(nums.ptr[i], Number).number;
		fprintf(file, "%s%" PRIu32, (i ? "," : ""), num);
	}
}

int main(int argc, char *argv[]) {
	int rppFlags = 0;
	const char *host = NULL;
	const char *port = "imaps";
	const char *mailbox = "INBOX";

	const char *subject = NULL;
	const char *from = NULL;
	const char *to = NULL;
	const char *cc = NULL;
	bool unseen = false;
	bool idle = false;
	bool body = true;

	const char *move = NULL;
	bool seen = false;

	int opt;
	while (0 < (opt = getopt(argc, argv, "C:F:HM:S:T:Uh:im:p:svw"))) {
		switch (opt) {
			break; case 'C': cc = optarg;
			break; case 'F': from = optarg;
			break; case 'H': body = false;
			break; case 'M': move = optarg;
			break; case 'S': subject = optarg;
			break; case 'T': to = optarg;
			break; case 'U': unseen = true;
			break; case 'h': host = optarg;
			break; case 'i': idle = true;
			break; case 'm': mailbox = optarg;
			break; case 'p': port = optarg;
			break; case 's': seen = true;
			break; case 'v': imapVerbose = true;
			break; case 'w': rppFlags |= RPP_STDIN;
			break; default:  return EX_USAGE;
		}
	}

	const char *user = argv[optind];
	if (!user) errx(EX_USAGE, "username required");

	if (!host) {
		host = strchr(user, '@');
		if (!host) errx(EX_USAGE, "no domain in username");
		host++;
	}

	char buf[1024];
	char *pass = readpassphrase(
		(rppFlags & RPP_STDIN ? "" : "Password: "),
		buf, sizeof(buf), rppFlags
	);
	if (!pass) err(EX_UNAVAILABLE, "readpassphrase");

	struct Resp resp;
	struct IMAP imap = imapOpen(host, port);
	respFree(respOk(imapResp(&imap)));

	enum Atom login = atom("login");
	fprintf(imap.w, "%s LOGIN \"%s\" \"%s\"\r\n", Atoms[login], user, pass);
	for (; resp = respOk(imapResp(&imap)), resp.tag != login; respFree(resp));
	respFree(resp);

	enum Atom examine = atom("examine");
	fprintf(
		imap.w, "%s %s \"%s\"\r\n",
		Atoms[examine], (move || seen ? "SELECT" : "EXAMINE"), mailbox
	);
	for (; resp = respOk(imapResp(&imap)), resp.tag != examine; respFree(resp));
	respFree(resp);

search:;
	struct List nums = {0};
	enum Atom search = atom("search");
	fprintf(imap.w, "%s SEARCH CHARSET UTF-8 ALL", Atoms[search]);
	if (subject) fprintf(imap.w, " SUBJECT \"%s\"", subject);
	if (from) fprintf(imap.w, " FROM \"%s\"", from);
	if (to) fprintf(imap.w, " TO \"%s\"", to);
	if (cc) fprintf(imap.w, " CC \"%s\"", cc);
	if (unseen) fprintf(imap.w, " UNSEEN");
	fprintf(imap.w, "\r\n");
	for (; resp = respOk(imapResp(&imap)), resp.tag != search; respFree(resp)) {
		if (resp.resp != AtomSearch) continue;
		nums = resp.data;
		resp.data = (struct List) {0};
	}
	respFree(resp);
	if (!nums.len) {
		if (!idle) errx(EX_TEMPFAIL, "no matching messages");
		respFree(respOk(imapIdle(&imap, atom("idle"))));
		goto search;
	}

	enum Atom fetch = atom("fetch");
	fprintf(imap.w, "%s FETCH ", Atoms[fetch]);
	printNums(imap.w, nums);
	fprintf(
		imap.w, " (BODY[HEADER.FIELDS (" FETCH_HEADERS ")]%s)\r\n",
		(body ? " BODY[TEXT]" : "")
	);
	for (; resp = respOk(imapResp(&imap)), resp.tag != fetch; respFree(resp)) {
		if (resp.resp != AtomFetch) continue;
		if (!resp.data.len) errx(EX_PROTOCOL, "missing fetch data");
		struct List items = dataCheck(resp.data.ptr[0], List).list;
		struct Data header = {0};
		struct Data body = {0};
		for (size_t i = 0; i + 2 < items.len; ++i) {
			struct Data item = items.ptr[i];
			if (item.type != Atom || item.atom != AtomBody) continue;
			if (items.ptr[i + 1].type != List) continue;
			struct List sect = items.ptr[i + 1].list;
			if (!sect.len || sect.ptr[0].type != Atom) continue;
			if (sect.ptr[0].atom == AtomHeader) {
				header = items.ptr[i + 2];
			} else if (sect.ptr[0].atom == AtomText) {
				body = items.ptr[i + 2];
			}
		}
		mboxrd(
			dataCheck(header, String).string,
			(body.type == String ? body.string : NULL)
		);
	}
	respFree(resp);

	if (seen) {
		enum Atom sto = atom("store");
		fprintf(imap.w, "%s STORE ", Atoms[sto]);
		printNums(imap.w, nums);
		fprintf(imap.w, " +FLAGS.SILENT (\\Seen)\r\n");
		for (; resp = respOk(imapResp(&imap)), resp.tag != sto; respFree(resp));
		respFree(resp);
	}

	if (move) {
		enum Atom mov = atom("move");
		fprintf(imap.w, "%s MOVE ", Atoms[mov]);
		printNums(imap.w, nums);
		fprintf(imap.w, " \"%s\"\r\n", move);
		for (; resp = respOk(imapResp(&imap)), resp.tag != mov; respFree(resp));
		respFree(resp);
	}

	fprintf(imap.w, "ayy LOGOUT\r\n");
	fclose(imap.r);
	fclose(imap.w);
}