use std::ffi::OsString;

use crate::{
    fallible,
    os::{Os, Target},
    Arch, DesktopEnv, Language, Platform, Result,
};

macro_rules! report_message {
    () => {
        "Please report this issue at https://github.com/ardaku/whoami/issues"
    };
}

const DEFAULT_USERNAME: &str = "Unknown";
const DEFAULT_HOSTNAME: &str = "LocalHost";

/// Get the CPU Architecture.
#[inline(always)]
pub fn arch() -> Arch {
    Target::arch(Os).expect(concat!("arch() failed.  ", report_message!()))
}

/// Get the user's username.
///
/// On unix-systems this differs from [`realname()`] most notably in that spaces
/// are not allowed in the username.
#[inline(always)]
pub fn username() -> String {
    fallible::username().unwrap_or_else(|_| DEFAULT_USERNAME.to_lowercase())
}

/// Get the user's username.
///
/// On unix-systems this differs from [`realname_os()`] most notably in that
/// spaces are not allowed in the username.
#[inline(always)]
pub fn username_os() -> OsString {
    fallible::username_os()
        .unwrap_or_else(|_| DEFAULT_USERNAME.to_lowercase().into())
}

/// Get the user's real (full) name.
#[inline(always)]
pub fn realname() -> String {
    fallible::realname()
        .or_else(|_| fallible::username())
        .unwrap_or_else(|_| DEFAULT_USERNAME.to_owned())
}

/// Get the user's real (full) name.
#[inline(always)]
pub fn realname_os() -> OsString {
    fallible::realname_os()
        .or_else(|_| fallible::username_os())
        .unwrap_or_else(|_| DEFAULT_USERNAME.to_owned().into())
}

/// Get the device name (also known as "Pretty Name").
///
/// Often used to identify device for bluetooth pairing.
#[inline(always)]
pub fn devicename() -> String {
    fallible::devicename()
        .or_else(|_| fallible::hostname())
        .unwrap_or_else(|_| DEFAULT_HOSTNAME.to_string())
}

/// Get the device name (also known as "Pretty Name").
///
/// Often used to identify device for bluetooth pairing.
#[inline(always)]
pub fn devicename_os() -> OsString {
    fallible::devicename_os()
        .or_else(|_| fallible::hostname().map(OsString::from))
        .unwrap_or_else(|_| DEFAULT_HOSTNAME.to_string().into())
}

/// Get the host device's hostname.
///
/// Limited to a-z (case insensitive), 0-9, and dashes.  This limit also applies
/// to `devicename()` with the exeception of case sensitivity when targeting
/// Windows.  This method normalizes to lowercase.  Usually hostnames will be
/// case-insensitive, but it's not a hard requirement.
///
/// Use [`fallible::hostname()`] for case-sensitive hostname.
#[inline(always)]
#[deprecated(note = "use `fallible::hostname()` instead", since = "1.5.0")]
pub fn hostname() -> String {
    let mut hostname = fallible::hostname()
        .unwrap_or_else(|_| DEFAULT_HOSTNAME.to_lowercase());

    hostname.make_ascii_lowercase();
    hostname
}

/// Get the host device's hostname.
///
/// Limited to a-z (case insensitive), 0-9, and dashes.  This limit also applies
/// to `devicename()` with the exeception of case sensitivity when targeting
/// Windows.  This method normalizes to lowercase.  Usually hostnames will be
/// case-insensitive, but it's not a hard requirement.
///
/// Use [`fallible::hostname()`] for case-sensitive hostname.
#[inline(always)]
#[deprecated(note = "use `fallible::hostname()` instead", since = "1.5.0")]
pub fn hostname_os() -> OsString {
    #[allow(deprecated)]
    hostname().into()
}

/// Get the name of the operating system distribution and (possibly) version.
///
/// Example: "Windows 10" or "Fedora 26 (Workstation Edition)"
#[inline(always)]
pub fn distro() -> String {
    fallible::distro().unwrap_or_else(|_| format!("Unknown {}", platform()))
}

/// Get the name of the operating system distribution and (possibly) version.
///
/// Example: "Windows 10" or "Fedora 26 (Workstation Edition)"
#[inline(always)]
#[deprecated(note = "use `distro()` instead", since = "1.5.0")]
pub fn distro_os() -> OsString {
    fallible::distro()
        .map(OsString::from)
        .unwrap_or_else(|_| format!("Unknown {}", platform()).into())
}

/// Get the desktop environment.
///
/// Example: "gnome" or "windows"
#[inline(always)]
pub fn desktop_env() -> DesktopEnv {
    Target::desktop_env(Os)
}

/// Get the platform.
#[inline(always)]
pub fn platform() -> Platform {
    Target::platform(Os)
}

/// Get the user's preferred language(s).
///
/// Returned as iterator of two letter language codes (lowercase), optionally
/// followed by a dash (-) and a two letter country code (uppercase).  The most
/// preferred language is returned first, followed by next preferred, and so on.
#[inline(always)]
#[deprecated(note = "use `langs()` instead", since = "1.5.0")]
pub fn lang() -> impl Iterator<Item = String> {
    let langs_vec = if let Ok(langs) = langs() {
        langs
            .map(|lang| lang.to_string().replace('/', "-"))
            .collect()
    } else {
        ["en-US".to_string()].to_vec()
    };

    langs_vec.into_iter()
}

/// Get the user's preferred language(s).
///
/// Returned as iterator of [`Language`]s.  The most preferred language is
/// returned first, followed by next preferred, and so on.  Unrecognized
/// languages may either return an error or be skipped.
#[inline(always)]
pub fn langs() -> Result<impl Iterator<Item = Language>> {
    // FIXME: Could do less allocation
    let langs = Target::langs(Os)?;
    let langs = langs
        .split(';')
        .map(ToString::to_string)
        .filter_map(|lang| {
            let lang = lang
                .split_terminator('.')
                .next()
                .unwrap_or_default()
                .replace(|x| ['_', '-'].contains(&x), "/");

            if lang == "C" {
                return None;
            }

            Some(Language::__(Box::new(lang)))
        });

    Ok(langs.collect::<Vec<_>>().into_iter())
}