const std = @import("std");
const os = std.os;
const builtin = @import("builtin");
const path = std.fs.path;
const fs = std.fs;
const lib = @import("./lib.zig");

const fmt = std.fmt;

const Kind = std.fs.File.Kind;
const PermissionsUnix = std.fs.File.PermissionsUnix;

// WON'T: human output => use human command instead
// TODO: error management.

pub const cwd = fs.cwd();

const Options = struct {
    verbose: bool = false,
};

var options: Options = Options {};

fn print_stats(fpath: []const u8, stats: os.system.Stat) !void {
    var buffer = [_]u8 {0} ** (std.fs.MAX_PATH_BYTES + 100);
    var writer = lib.FixedBufferWriter.init(&buffer);

    // print kind (directory, file, pipe, etc.)
    const kind = fs.File.Stat.systemStatKindToFsKind(stats);
    switch (kind) {
        .File             => try writer.put("-"),
        .Directory        => try writer.put("d"),
        .CharacterDevice  => try writer.put("c"),
        .BlockDevice      => try writer.put("b"),
        .NamedPipe        => try writer.put("p"),
        .SymLink          => try writer.put("s"),
        .UnixDomainSocket => try writer.put("s"),
        else              => {
            if (builtin.os.tag == .solaris) switch (kind) {
                .Door      => try writer.put("D"), // TODO: what to print here?
                .EventPort => try writer.put("e"), // TODO: what to print here?
                else       => try writer.put("?"),
            };
        },
    }

    // print rights
    const perms = PermissionsUnix.unixNew(stats.mode);
    const classes = [_]PermissionsUnix.Class {
        PermissionsUnix.Class.user,
        PermissionsUnix.Class.group,
        PermissionsUnix.Class.other
    };
    const rights = [_]PermissionsUnix.Permission {
        PermissionsUnix.Permission.read,
        PermissionsUnix.Permission.write,
        PermissionsUnix.Permission.execute
    };
    for (classes) |c| {
        for (rights) |r| {
             if (perms.unixHas(c,r)) {
                 switch(r) {
                     .read    => try writer.put("r"),
                     .write   => try writer.put("w"),
                     .execute => try writer.put("x"),
                 }
             }
             else {
                 try writer.put("-");
             }
        }
    }

    // TODO: print user & group, not just uid and gid
    try writer.putf("\t{}\t{}\t", .{stats.uid, stats.gid});
    try writer.putf("{}\t",       .{stats.size});
    try writer.putf("{}\t",       .{stats.mtim.tv_sec});
    try writer.putf("{s}\n",      .{fpath});

    return lib.print("{s}", .{writer.getWritten()});
}

fn print_file (fpath: []const u8) !void {
    if (options.verbose == false) {
        return lib.print("{s}\n", .{fpath});
    }

    const dname = path.dirname(fpath);
    var dpath = dname orelse ".";
    var dir: fs.Dir = cwd.openDir(dpath, .{}) catch |err| switch (err) {
        error.AccessDenied => return lib.print("{s}: access denied\n", .{dname}),
        else => return err,
    };

    const bname = path.basename(fpath);
    try print_file_in_dir (dir, bname);
}

fn print_file_in_dir (dir: fs.Dir, entryname: []const u8) !void {
    if (options.verbose == false) {
        return lib.print("{s}\n", .{entryname});
    }

    return try print_stats (entryname, try dir.fstatat(entryname));
}

// Either print directory's content or file.
fn print_directory(fpath: []const u8) !void {
    var dir: fs.Dir = cwd.openDir(fpath, .{.iterate = true}) catch |err| switch (err) {
        error.AccessDenied => return lib.print("{s}: access denied\n", .{fpath}),
        error.NotDir => {
            // fpath is a simple file, just print the file infos
            return try print_file(fpath);
        },
        else => return err,
    };

    // fpath is a directory: print info on each file
    var dir_it = dir.iterate();
    while (try dir_it.next()) |entry| {
        try print_file_in_dir (dir, entry.name);
    }
}

pub fn ls() !void {
    var cli = try lib.CLI.init();
    defer cli.deinit();

    // Skipping the executable binary name.
    var arg_idx: usize = 1;
    var nb_parameters: i32 = 0;

    // case there are parameters
    while(arg_idx < cli.args.len) {
        const element = cli.nextArg(&arg_idx) orelse {
            lib.warn("Null argument\n", .{});
            return error.InvalidArgs;
        };
        if (std.mem.eql(u8, element, "-l")) {
            options.verbose = true;
        }
        else {
            nb_parameters += 1;
            try print_directory(element);
        }
    }

    // case there were no parameter, print current directory
    if (nb_parameters == 0) {
        try print_directory(".");
    }
}

pub fn main() !void {
    try ls();
}