/*
 * esv: read the Bible from your terminal
 *
 * The GPLv2 License (GPLv2)
 * Copyright (c) 2023-2024 Jeremy Baxter
 * 
 * esv 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 2 of the License, or
 * (at your option) any later version.
 * 
 * esv 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 esv.  If not, see <http://www.gnu.org/licenses/>.
 */

module esv;

import std.algorithm : startsWith;
import std.conv    : to, ConvException;
import std.file    : exists, mkdirRecurse, write, FileException;
import std.format  : format;
import std.getopt  : getopt, GetOptException;
import std.path    : baseName, dirName, expandTilde, isValidPath;
import std.process : environment, executeShell;
import std.stdio   : writef, writeln, writefln, File;
import std.string  : splitLines;

import esvapi;
import initial;

import cf = config;

@safe:

bool   aFlag;        /* audio */
string CFlag;        /* config */
bool   fFlag, FFlag; /* footnotes */
bool   hFlag, HFlag; /* headings */
int    lFlag;        /* line length */
bool   lFlagSpecified;
bool   nFlag, NFlag; /* verse numbers */
bool   rFlag, RFlag; /* passage references */
string sFlag;        /* search passages */
bool   VFlag;        /* show version */

string[] mainArgs;
File stderr;

version (OpenBSD) {
	immutable(char) *promises;
}

int
main(string[] args)
{
	string apiKey;
	string configPath;
	INIUnit ini;
	ESVApi esv;

	mainArgs = args;

	version (OpenBSD) () @trusted {
		import core.sys.openbsd.unistd : pledge;
		import std.string : toStringz;

		promises = toStringz("stdio rpath wpath cpath inet dns tty proc exec prot_exec");
		pledge(promises, null);
	}();

	/* @safe way of opening stderr on Unix */
	stderr = File("/dev/stderr", "w");

	/* Parse command-line options */
	try {
		import std.getopt : config;
		getopt(args,
			config.bundling,
			config.caseSensitive,
			"a", &aFlag,
			"C", &CFlag,
			"F", &FFlag, "f", &fFlag,
			"H", &HFlag, "h", &hFlag,
			"l", &onLineLength,
			"N", &NFlag, "n", &nFlag,
			"R", &RFlag, "r", &rFlag,
			"s", &sFlag,
			"V", &VFlag,
		);
	} catch (GetOptException e) {
		string opt = extractOpt(e);

		enforceDie(!e.msg.startsWith("Unrecognized option"),
			"unknown option " ~ opt);
		enforceDie(!e.msg.startsWith("Missing value for argument"),
			"missing argument for option " ~ opt);

		die(e.msg); /* catch-all */
	}

	if (VFlag) {
		writeln("esv " ~ cf.esvVersion);
		return 0;
	}

	if (sFlag != "") {
		/* skip argument validation */
		goto config;
	}

	if (args.length < 3) {
		stderr.writefln(
			"usage: %s [-aFfHhNnRrV] [-C config] [-l length] [-s query] book verses",
				baseName(args[0]));
		return 1;
	}

	enforceDie(bookValid(parseBook(args[1])),
		"book '%s' does not exist", args[1]);
	enforceDie(verseValid(args[2]),
		"invalid verse format '%s'", args[2]);

	/* determine configuration file: options take first priority,
	 * then environment variables, and then the default path */
config:
	configPath = environment.get(cf.configEnv, cf.configPath)
		.expandTilde();
	try {
		if (CFlag != "") { /* if -C was given */
			enforceDie(CFlag.isValidPath(), CFlag ~ ": invalid path");
			configPath = CFlag.expandTilde();
		} else {
			enforceDie(configPath.isValidPath(),
				configPath ~ ": invalid path");

			if (!configPath.exists()) {
				mkdirRecurse(dirName(configPath));
				configPath.write(format!
"## Configuration file for esv.

# An API key is required to access the ESV Bible API.
[api]
key = %s

# Settings that modify how passages are displayed:
[passage]
#footnotes = false
#headings = false
#passage-references = false
#verse-numbers = false
"(cf.apiKey));
			}
		}
		readINIFile(ini, configPath);
	} catch (FileException e) {
		/* filesystem syscall errors */
		die(e.msg);
	}

	enforceDie(!(aFlag && sFlag), "cannot specify both -a and -s flags");

	apiKey = ini["api"].key("key");
	enforceDie(apiKey != null,
		"API key not present in configuration file; cannot proceed");

	esv = new ESVApi(apiKey);

	if (aFlag) {
		string tmpf, player;

		try
			tmpf = esv.getAudioPassage(args[1], args[2]);
		catch (CurlException e)
			die(e.msg);
		player = environment.get(cf.playerEnv, cf.mp3Player);

		/* check for an audio player */
		enforceDie(
			executeShell(
				format!"command -v %s >/dev/null 2>&1"(player)
			).status == 0,
			player ~ " is required for audio mode; cannot continue");

		/* esv has built-in support for mpg123 and mpv.
		 * Other players will work, just set ESV_PLAYER */
		player ~=
			player == "mpg123" ? " -q " :
			player == "mpv"    ? " --msg-level=all=no " : " ";
		/* spawn the player */
		executeShell(player ~ tmpf);
		return 0;
	}

	if (sFlag) {
		try
			writeln(esv.searchFormat(sFlag));
		catch (ESVException)
			die("no results for search");
		catch (CurlException e)
			die(e.msg);
		return 0;
	}

	esv.extraParameters = ini["api"].key("parameters", "");

	/* Get [passage] keys */
	foreach (string key; [
		"footnotes",
		"headings",
		"passage-references",
		"verse-numbers"
	]) {
		try
			esv.opts.b["include-" ~ key] =
				ini["passage"].keyAs!bool(key, true);
		catch (INITypeException e)
			die(configPath ~ ": " ~ e.msg);
	}
	/* Get line-length ([passage]) */
	try
		esv.opts.i["line-length"] =
			lFlagSpecified ? lFlag :
			ini["passage"].keyAs!int("line-length", terminalColumns());
	catch (INITypeException e)
		die(configPath ~ ": " ~ e.msg);

	if (fFlag) esv.opts.b["include-footnotes"]          = true;
	if (hFlag) esv.opts.b["include-headings"]           = true;
	if (nFlag) esv.opts.b["include-verse-numbers"]      = true;
	if (rFlag) esv.opts.b["include-passage-references"] = true;
	if (FFlag) esv.opts.b["include-footnotes"]          = false;
	if (HFlag) esv.opts.b["include-headings"]           = false;
	if (NFlag) esv.opts.b["include-verse-numbers"]      = false;
	if (RFlag) esv.opts.b["include-passage-references"] = false;

	try
		writeln(esv.getPassage(parseBook(args[1]), args[2]));
	catch (CurlException e)
		die(e.msg);
	return 0;
}

private void
warn(string mesg)
{
	stderr.writeln(baseName(mainArgs[0]) ~ ": " ~ mesg);
}

private void
die(string mesg) @trusted
{
	import core.runtime : Runtime;
	import core.stdc.stdlib : exit;

	warn(mesg);
	Runtime.terminate();
	exit(1);
}

private ushort
terminalColumns() @trusted
{
	import core.sys.posix.sys.ioctl;

	winsize w;

	ioctl(1, TIOCGWINSZ, &w);
	return w.ws_col > 72 ? 72 : w.ws_col;
}

private void
enforceDie(A...)(bool cond, string fmt, A a)
{
	import std.format : format;

	if (!cond)
		die(format(fmt, a));
}

private string
extractOpt(in GetOptException e)
{
	import std.regex : matchFirst;

	return e.msg.matchFirst("-.")[0];
}

private void
onLineLength(string flag, string value)
{
	lFlagSpecified = true;
	try
		lFlag = value.to!int();
	catch (ConvException e)
		die("illegal argument to -l option -- must be a positive integer");
}

private string
parseBook(in string book)
{
	import std.string : tr;

	return book.tr("-_", "  ");
}