// Take a look at the license at the top of the repository in the LICENSE file.

use crate::sys::cpu::*;
#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
use crate::sys::process::*;
use crate::sys::utils::{get_sys_value, get_sys_value_by_name};

use crate::{
    Cpu, CpuRefreshKind, LoadAvg, MemoryRefreshKind, Pid, Process, ProcessRefreshKind,
    ProcessesToUpdate,
};

#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
use std::cell::UnsafeCell;
use std::collections::HashMap;
use std::ffi::CStr;
use std::mem;
use std::time::Duration;
#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
use std::time::SystemTime;

use libc::{
    c_int, c_void, host_statistics64, mach_port_t, sysconf, sysctl, timeval, vm_statistics64,
    _SC_PAGESIZE,
};

#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
declare_signals! {
    libc::c_int,
    Signal::Hangup => libc::SIGHUP,
    Signal::Interrupt => libc::SIGINT,
    Signal::Quit => libc::SIGQUIT,
    Signal::Illegal => libc::SIGILL,
    Signal::Trap => libc::SIGTRAP,
    Signal::Abort => libc::SIGABRT,
    Signal::IOT => libc::SIGIOT,
    Signal::Bus => libc::SIGBUS,
    Signal::FloatingPointException => libc::SIGFPE,
    Signal::Kill => libc::SIGKILL,
    Signal::User1 => libc::SIGUSR1,
    Signal::Segv => libc::SIGSEGV,
    Signal::User2 => libc::SIGUSR2,
    Signal::Pipe => libc::SIGPIPE,
    Signal::Alarm => libc::SIGALRM,
    Signal::Term => libc::SIGTERM,
    Signal::Child => libc::SIGCHLD,
    Signal::Continue => libc::SIGCONT,
    Signal::Stop => libc::SIGSTOP,
    Signal::TSTP => libc::SIGTSTP,
    Signal::TTIN => libc::SIGTTIN,
    Signal::TTOU => libc::SIGTTOU,
    Signal::Urgent => libc::SIGURG,
    Signal::XCPU => libc::SIGXCPU,
    Signal::XFSZ => libc::SIGXFSZ,
    Signal::VirtualAlarm => libc::SIGVTALRM,
    Signal::Profiling => libc::SIGPROF,
    Signal::Winch => libc::SIGWINCH,
    Signal::IO => libc::SIGIO,
    // SIGPOLL doesn't exist on apple targets but since it's an equivalent of SIGIO on unix,
    // we simply use the SIGIO constant.
    Signal::Poll => libc::SIGIO,
    Signal::Sys => libc::SIGSYS,
    _ => None,
}
#[cfg(any(target_os = "ios", feature = "apple-sandbox"))]
declare_signals! {
    libc::c_int,
    _ => None,
}

#[doc = include_str!("../../../md_doc/supported_signals.md")]
pub const SUPPORTED_SIGNALS: &[crate::Signal] = supported_signals();
#[doc = include_str!("../../../md_doc/minimum_cpu_update_interval.md")]
pub const MINIMUM_CPU_UPDATE_INTERVAL: Duration = Duration::from_millis(200);

pub(crate) struct SystemInner {
    process_list: HashMap<Pid, Process>,
    mem_total: u64,
    mem_free: u64,
    mem_used: u64,
    mem_available: u64,
    swap_total: u64,
    swap_free: u64,
    page_size_b: u64,
    port: mach_port_t,
    #[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
    clock_info: Option<crate::sys::macos::system::SystemTimeInfo>,
    cpus: CpusWrapper,
}

#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
pub(crate) struct Wrap<'a>(pub UnsafeCell<&'a mut HashMap<Pid, Process>>);

#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
unsafe impl Send for Wrap<'_> {}
#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
unsafe impl Sync for Wrap<'_> {}

fn boot_time() -> u64 {
    let mut boot_time = timeval {
        tv_sec: 0,
        tv_usec: 0,
    };
    let mut len = std::mem::size_of::<timeval>();
    let mut mib: [c_int; 2] = [libc::CTL_KERN, libc::KERN_BOOTTIME];

    unsafe {
        if sysctl(
            mib.as_mut_ptr(),
            mib.len() as _,
            &mut boot_time as *mut timeval as *mut _,
            &mut len,
            std::ptr::null_mut(),
            0,
        ) < 0
        {
            0
        } else {
            boot_time.tv_sec as _
        }
    }
}

#[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
fn get_now() -> u64 {
    SystemTime::now()
        .duration_since(SystemTime::UNIX_EPOCH)
        .map(|n| n.as_secs())
        .unwrap_or(0)
}

impl SystemInner {
    pub(crate) fn new() -> Self {
        unsafe {
            #[allow(deprecated)]
            let port = libc::mach_host_self();

            Self {
                process_list: HashMap::with_capacity(200),
                mem_total: 0,
                mem_free: 0,
                mem_available: 0,
                mem_used: 0,
                swap_total: 0,
                swap_free: 0,
                page_size_b: sysconf(_SC_PAGESIZE) as _,
                port,
                #[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
                clock_info: crate::sys::macos::system::SystemTimeInfo::new(port),
                cpus: CpusWrapper::new(),
            }
        }
    }

    pub(crate) fn refresh_memory_specifics(&mut self, refresh_kind: MemoryRefreshKind) {
        let mut mib = [libc::CTL_VM as _, libc::VM_SWAPUSAGE as _];

        unsafe {
            if refresh_kind.swap() {
                // get system values
                // get swap info
                let mut xs: libc::xsw_usage = mem::zeroed::<libc::xsw_usage>();
                if get_sys_value(
                    mem::size_of::<libc::xsw_usage>(),
                    &mut xs as *mut _ as *mut c_void,
                    &mut mib,
                ) {
                    self.swap_total = xs.xsu_total;
                    self.swap_free = xs.xsu_avail;
                }
            }
            if refresh_kind.ram() {
                mib[0] = libc::CTL_HW as _;
                mib[1] = libc::HW_MEMSIZE as _;
                // get ram info
                if self.mem_total < 1 {
                    get_sys_value(
                        mem::size_of::<u64>(),
                        &mut self.mem_total as *mut u64 as *mut c_void,
                        &mut mib,
                    );
                }
                let mut count: u32 = libc::HOST_VM_INFO64_COUNT as _;
                let mut stat = mem::zeroed::<vm_statistics64>();
                if host_statistics64(
                    self.port,
                    libc::HOST_VM_INFO64,
                    &mut stat as *mut vm_statistics64 as *mut _,
                    &mut count,
                ) == libc::KERN_SUCCESS
                {
                    // From the apple documentation:
                    //
                    // /*
                    //  * NB: speculative pages are already accounted for in "free_count",
                    //  * so "speculative_count" is the number of "free" pages that are
                    //  * used to hold data that was read speculatively from disk but
                    //  * haven't actually been used by anyone so far.
                    //  */
                    self.mem_available = u64::from(stat.free_count)
                        .saturating_add(u64::from(stat.inactive_count))
                        .saturating_add(u64::from(stat.purgeable_count))
                        .saturating_sub(u64::from(stat.compressor_page_count))
                        .saturating_mul(self.page_size_b);
                    self.mem_used = u64::from(stat.active_count)
                        .saturating_add(u64::from(stat.wire_count))
                        .saturating_add(u64::from(stat.compressor_page_count))
                        .saturating_add(u64::from(stat.speculative_count))
                        .saturating_mul(self.page_size_b);
                    self.mem_free = u64::from(stat.free_count)
                        .saturating_sub(u64::from(stat.speculative_count))
                        .saturating_mul(self.page_size_b);
                }
            }
        }
    }

    pub(crate) fn cgroup_limits(&self) -> Option<crate::CGroupLimits> {
        None
    }

    pub(crate) fn refresh_cpu_specifics(&mut self, refresh_kind: CpuRefreshKind) {
        self.cpus.refresh(refresh_kind, self.port);
    }

    pub(crate) fn refresh_cpu_list(&mut self, refresh_kind: CpuRefreshKind) {
        self.cpus = CpusWrapper::new();
        self.cpus.refresh(refresh_kind, self.port);
    }

    #[cfg(any(target_os = "ios", feature = "apple-sandbox"))]
    pub(crate) fn refresh_processes_specifics(
        &mut self,
        _processes_to_update: ProcessesToUpdate<'_>,
        _refresh_kind: ProcessRefreshKind,
    ) -> usize {
        0
    }

    #[cfg(all(target_os = "macos", not(feature = "apple-sandbox")))]
    pub(crate) fn refresh_processes_specifics(
        &mut self,
        processes_to_update: ProcessesToUpdate<'_>,
        refresh_kind: ProcessRefreshKind,
    ) -> usize {
        use crate::utils::into_iter;
        use std::sync::atomic::{AtomicUsize, Ordering};

        unsafe {
            let count = libc::proc_listallpids(::std::ptr::null_mut(), 0);
            if count < 1 {
                return 0;
            }
        }
        if let Some(pids) = get_proc_list() {
            #[inline(always)]
            fn real_filter(e: Pid, filter: &[Pid]) -> bool {
                filter.contains(&e)
            }

            #[inline(always)]
            fn empty_filter(_e: Pid, _filter: &[Pid]) -> bool {
                true
            }

            #[allow(clippy::type_complexity)]
            let (filter, filter_callback): (
                &[Pid],
                &(dyn Fn(Pid, &[Pid]) -> bool + Sync + Send),
            ) = match processes_to_update {
                ProcessesToUpdate::All => (&[], &empty_filter),
                ProcessesToUpdate::Some(pids_to_refresh) => {
                    if pids_to_refresh.is_empty() {
                        return 0;
                    }
                    (pids_to_refresh, &real_filter)
                }
            };

            let nb_updated = AtomicUsize::new(0);
            let now = get_now();
            let port = self.port;
            let time_interval = self.clock_info.as_mut().map(|c| c.get_time_interval(port));
            let timebase_to_ms = self
                .clock_info
                .as_ref()
                .map(|c| c.timebase_to_ms)
                .unwrap_or_default();
            let entries: Vec<Process> = {
                let wrap = &Wrap(UnsafeCell::new(&mut self.process_list));

                #[cfg(feature = "multithread")]
                use rayon::iter::ParallelIterator;

                into_iter(pids)
                    .flat_map(|pid| {
                        if !filter_callback(pid, filter) {
                            return None;
                        }
                        nb_updated.fetch_add(1, Ordering::Relaxed);
                        update_process(
                            wrap,
                            pid,
                            time_interval,
                            now,
                            refresh_kind,
                            false,
                            timebase_to_ms,
                        )
                        .unwrap_or_default()
                    })
                    .collect()
            };
            entries.into_iter().for_each(|entry| {
                self.process_list.insert(entry.pid(), entry);
            });
            nb_updated.into_inner()
        } else {
            0
        }
    }

    // COMMON PART
    //
    // Need to be moved into a "common" file to avoid duplication.

    pub(crate) fn processes(&self) -> &HashMap<Pid, Process> {
        &self.process_list
    }

    pub(crate) fn processes_mut(&mut self) -> &mut HashMap<Pid, Process> {
        &mut self.process_list
    }

    pub(crate) fn process(&self, pid: Pid) -> Option<&Process> {
        self.process_list.get(&pid)
    }

    pub(crate) fn global_cpu_usage(&self) -> f32 {
        self.cpus.global_cpu.percent()
    }

    pub(crate) fn cpus(&self) -> &[Cpu] {
        &self.cpus.cpus
    }

    pub(crate) fn total_memory(&self) -> u64 {
        self.mem_total
    }

    pub(crate) fn free_memory(&self) -> u64 {
        self.mem_free
    }

    pub(crate) fn available_memory(&self) -> u64 {
        self.mem_available
    }

    pub(crate) fn used_memory(&self) -> u64 {
        self.mem_used
    }

    pub(crate) fn total_swap(&self) -> u64 {
        self.swap_total
    }

    pub(crate) fn free_swap(&self) -> u64 {
        self.swap_free
    }

    // TODO: need to be checked
    pub(crate) fn used_swap(&self) -> u64 {
        self.swap_total - self.swap_free
    }

    pub(crate) fn uptime() -> u64 {
        unsafe {
            let csec = libc::time(::std::ptr::null_mut());

            libc::difftime(csec, Self::boot_time() as _) as _
        }
    }

    pub(crate) fn load_average() -> LoadAvg {
        let mut loads = vec![0f64; 3];

        unsafe {
            libc::getloadavg(loads.as_mut_ptr(), 3);
            LoadAvg {
                one: loads[0],
                five: loads[1],
                fifteen: loads[2],
            }
        }
    }

    pub(crate) fn boot_time() -> u64 {
        boot_time()
    }

    pub(crate) fn name() -> Option<String> {
        get_system_info(libc::KERN_OSTYPE, Some("Darwin"))
    }

    pub(crate) fn long_os_version() -> Option<String> {
        #[cfg(target_os = "macos")]
        {
            let Some(os_version) = Self::os_version() else {
                return Some("macOS".to_owned());
            };
            // https://en.wikipedia.org/wiki/MacOS_version_history
            for (version_prefix, macos_spelling, friendly_name) in [
                ("15", "macOS", "Sequoia"),
                ("14", "macOS", "Sonoma"),
                ("13", "macOS", "Ventura"),
                ("12", "macOS", "Monterey"),
                ("11", "macOS", "Big Sur"),
                // Big Sur identifies itself as 10.16 in some situations.
                // https://en.wikipedia.org/wiki/MacOS_Big_Sur#Development_history
                ("10.16", "macOS", "Big Sur"),
                ("10.15", "macOS", "Catalina"),
                ("10.14", "macOS", "Mojave"),
                ("10.13", "macOS", "High Sierra"),
                ("10.12", "macOS", "Sierra"),
                ("10.11", "OS X", "El Capitan"),
                ("10.10", "OS X", "Yosemite"),
                ("10.9", "OS X", "Mavericks"),
                ("10.8", "OS X", "Mountain Lion"),
                ("10.7", "Mac OS X", "Lion"),
                ("10.6", "Mac OS X", "Snow Leopard"),
                ("10.5", "Mac OS X", "Leopard"),
                ("10.4", "Mac OS X", "Tiger"),
                ("10.3", "Mac OS X", "Panther"),
                ("10.2", "Mac OS X", "Jaguar"),
                ("10.1", "Mac OS X", "Puma"),
                ("10.0", "Mac OS X", "Cheetah"),
            ] {
                if os_version.starts_with(version_prefix) {
                    return Some(format!("{macos_spelling} {os_version} {friendly_name}"));
                }
            }
            Some(format!("macOS {os_version}"))
        }

        #[cfg(target_os = "ios")]
        {
            let mut long_name = "iOS".to_owned();
            if let Some(os_version) = Self::os_version() {
                long_name.push(' ');
                long_name.push_str(&os_version);
            }
            Some(long_name)
        }
    }

    pub(crate) fn host_name() -> Option<String> {
        get_system_info(libc::KERN_HOSTNAME, None)
    }

    pub(crate) fn kernel_version() -> Option<String> {
        get_system_info(libc::KERN_OSRELEASE, None)
    }

    pub(crate) fn os_version() -> Option<String> {
        unsafe {
            // get the size for the buffer first
            let mut size = 0;
            if get_sys_value_by_name(b"kern.osproductversion\0", &mut size, std::ptr::null_mut())
                && size > 0
            {
                // now create a buffer with the size and get the real value
                let mut buf = vec![0_u8; size as _];

                if get_sys_value_by_name(
                    b"kern.osproductversion\0",
                    &mut size,
                    buf.as_mut_ptr() as *mut c_void,
                ) {
                    if let Some(pos) = buf.iter().position(|x| *x == 0) {
                        // Shrink buffer to terminate the null bytes
                        buf.resize(pos, 0);
                    }

                    String::from_utf8(buf).ok()
                } else {
                    // getting the system value failed
                    None
                }
            } else {
                // getting the system value failed, or did not return a buffer size
                None
            }
        }
    }

    pub(crate) fn distribution_id() -> String {
        std::env::consts::OS.to_owned()
    }

    pub(crate) fn distribution_id_like() -> Vec<String> {
        Vec::new()
    }

    pub(crate) fn kernel_name() -> Option<&'static str> {
        Some("Darwin")
    }

    pub(crate) fn cpu_arch() -> Option<String> {
        let mut arch_str: [u8; 32] = [0; 32];
        let mut mib = [libc::CTL_HW as _, libc::HW_MACHINE as _];

        unsafe {
            if get_sys_value(
                mem::size_of::<[u8; 32]>(),
                arch_str.as_mut_ptr() as *mut _,
                &mut mib,
            ) {
                CStr::from_bytes_until_nul(&arch_str)
                    .ok()
                    .and_then(|res| match res.to_str() {
                        Ok(arch) => Some(arch.to_string()),
                        Err(_) => None,
                    })
            } else {
                None
            }
        }
    }

    pub(crate) fn physical_core_count() -> Option<usize> {
        physical_core_count()
    }

    // FIXME: Would be better to query this information instead of using a "default" value like this.
    pub(crate) fn open_files_limit() -> Option<usize> {
        #[cfg(target_os = "ios")]
        {
            Some(256)
        }
        #[cfg(not(target_os = "ios"))]
        {
            Some(10_240)
        }
    }
}

fn get_system_info(value: c_int, default: Option<&str>) -> Option<String> {
    let mut mib: [c_int; 2] = [libc::CTL_KERN, value];
    let mut size = 0;

    unsafe {
        // Call first to get size
        sysctl(
            mib.as_mut_ptr(),
            mib.len() as _,
            std::ptr::null_mut(),
            &mut size,
            std::ptr::null_mut(),
            0,
        );

        // exit early if we did not update the size
        if size == 0 {
            default.map(|s| s.to_owned())
        } else {
            // set the buffer to the correct size
            let mut buf = vec![0_u8; size as _];

            if sysctl(
                mib.as_mut_ptr(),
                mib.len() as _,
                buf.as_mut_ptr() as _,
                &mut size,
                std::ptr::null_mut(),
                0,
            ) == -1
            {
                // If command fails return default
                default.map(|s| s.to_owned())
            } else {
                if let Some(pos) = buf.iter().position(|x| *x == 0) {
                    // Shrink buffer to terminate the null bytes
                    buf.resize(pos, 0);
                }

                String::from_utf8(buf).ok()
            }
        }
    }
}
