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// Copyright (C) 2025 Shota FUJI
//
// 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/>.
//
// SPDX-License-Identifier: GPL-3.0-only

const std = @import("std");
const config = @import("config");

const RunOptions = @import("./RunOptions.zig");

const c = @cImport({
    @cInclude("time.h");
    @cInclude("sunriset.h");
});

const ExitCode = enum(u8) {
    ok = 0,
    generic_error = 1,
    day = 2,
    night = 3,
    out_of_memory = 10,
    stdout_write_error = 11,

    pub fn code(self: ExitCode) u8 {
        return @intFromEnum(self);
    }
};

fn writeHelp(writer: anytype, bin: []const u8) !void {
    try std.fmt.format(writer,
        \\[Usage]
        \\{s} [options...] <command> [parameters...]
        \\
        \\[Options]
        \\-v, --version   Prints version to stdout and exits.
        \\-h, --help      Prints this message to stdout and exits.
        \\
        \\[Commands]
        \\poll     Prints whether it's DAY or NIGHT.
        \\wait     Sleep until sunrise and/or sunset, then exits.
        \\report   Prints sunrise and sunset times.
        \\list     List sunrise and sunset times for next <DAYS>.
        \\
        \\[Common Parameters]
        \\TWILIGHT      Twilight type. Valid values are:
        \\              * daylight
        \\              * civil
        \\              * nautical
        \\              * astronomical
        \\              * angle <degree>
        \\EVENT TYPE    Use "rise" for sunrise and "set" for sunset.
        \\              If this parameter is not set, sunwait targets both.
        \\OFFSET        Time offset for sunrise and sunset time, towards noon.
        \\              Format must be "MM" (minutes) or "HH:MM".
        \\LATITUDE      Angle in degree, positive floating point number.
        \\              Must have N or S suffix.
        \\LONGITUDE     Angle in degree, positive floating point number.
        \\              Must have E or W suffix.
        \\
        \\See man page for "sunwait(1)" for more.
        \\
    , .{bin});
}

pub fn main() u8 {
    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    defer arena.deinit();

    const allocator = arena.allocator();

    const opts = RunOptions.init();
    var c_opts = opts.toC();

    var args = std.process.ArgIterator.initWithAllocator(allocator) catch {
        return ExitCode.out_of_memory.code();
    };
    defer args.deinit();

    const bin_name = args.next() orelse {
        std.log.err("Got no arguments, exiting.", .{});
        return ExitCode.generic_error.code();
    };

    while (args.next()) |arg| {
        if (std.mem.eql(u8, "-v", arg) or std.mem.eql(u8, "--version", arg)) {
            std.fmt.format(std.io.getStdOut().writer(), "{s}\n", .{config.version}) catch |err| {
                std.log.err("Unable to write to stdout: {s}", .{@errorName(err)});
                return ExitCode.stdout_write_error.code();
            };

            return ExitCode.ok.code();
        }

        if (std.mem.eql(u8, "-h", arg) or std.mem.eql(u8, "--help", arg)) {
            writeHelp(std.io.getStdOut().writer(), bin_name) catch |err| {
                std.log.err("Unable to write help message to stdout: {s}", .{@errorName(err)});
                return ExitCode.stdout_write_error.code();
            };

            return ExitCode.ok.code();
        }
    }

    return switch (c.sunpoll(&c_opts)) {
        c.EXIT_DAY => ExitCode.day.code(),
        c.EXIT_NIGHT => ExitCode.night.code(),
        else => ExitCode.generic_error.code(),
    };
}