use nu_protocol::{
    ast::Call,
    engine::{Command, EvaluationContext},
    Example, ShellError, Signature, Span, Value,
};
use sysinfo::{ComponentExt, DiskExt, NetworkExt, ProcessorExt, System, SystemExt, UserExt};

pub struct Sys;

impl Command for Sys {
    fn name(&self) -> &str {
        "sys"
    }

    fn signature(&self) -> Signature {
        Signature::build("sys")
            .desc("View information about the current system.")
            .filter()
    }

    fn usage(&self) -> &str {
        "View information about the system."
    }

    fn run(
        &self,
        _context: &EvaluationContext,
        call: &Call,
        _input: Value,
    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
        run_sys(call)
    }

    fn examples(&self) -> Vec<Example> {
        vec![Example {
            description: "Show info about the system",
            example: "sys",
            result: None,
        }]
    }
}

fn run_sys(call: &Call) -> Result<Value, ShellError> {
    let span = call.head;
    let mut sys = System::new();

    let mut headers = vec![];
    let mut values = vec![];

    if let Some(value) = host(&mut sys, span) {
        headers.push("host".into());
        values.push(value);
    }
    if let Some(value) = cpu(&mut sys, span) {
        headers.push("cpu".into());
        values.push(value);
    }
    if let Some(value) = disks(&mut sys, span) {
        headers.push("disks".into());
        values.push(value);
    }
    if let Some(value) = mem(&mut sys, span) {
        headers.push("mem".into());
        values.push(value);
    }
    if let Some(value) = temp(&mut sys, span) {
        headers.push("temp".into());
        values.push(value);
    }
    if let Some(value) = net(&mut sys, span) {
        headers.push("net".into());
        values.push(value);
    }

    Ok(Value::Record {
        cols: headers,
        vals: values,
        span,
    })
}

pub fn trim_cstyle_null(s: String) -> String {
    s.trim_matches(char::from(0)).to_string()
}

pub fn disks(sys: &mut System, span: Span) -> Option<Value> {
    sys.refresh_disks();
    sys.refresh_disks_list();

    let mut output = vec![];
    for disk in sys.disks() {
        let mut cols = vec![];
        let mut vals = vec![];

        cols.push("device".into());
        vals.push(Value::String {
            val: trim_cstyle_null(disk.name().to_string_lossy().to_string()),
            span,
        });

        cols.push("type".into());
        vals.push(Value::String {
            val: trim_cstyle_null(String::from_utf8_lossy(disk.file_system()).to_string()),
            span,
        });

        cols.push("mount".into());
        vals.push(Value::String {
            val: disk.mount_point().to_string_lossy().to_string(),
            span,
        });

        cols.push("total".into());
        vals.push(Value::Filesize {
            val: disk.total_space(),
            span,
        });

        cols.push("free".into());
        vals.push(Value::Filesize {
            val: disk.available_space(),
            span,
        });

        output.push(Value::Record { cols, vals, span });
    }
    if !output.is_empty() {
        Some(Value::List { vals: output, span })
    } else {
        None
    }
}

pub fn net(sys: &mut System, span: Span) -> Option<Value> {
    sys.refresh_networks();
    sys.refresh_networks_list();

    let mut output = vec![];
    for (iface, data) in sys.networks() {
        let mut cols = vec![];
        let mut vals = vec![];

        cols.push("name".into());
        vals.push(Value::String {
            val: trim_cstyle_null(iface.to_string()),
            span,
        });

        cols.push("sent".into());
        vals.push(Value::Filesize {
            val: data.total_transmitted(),
            span,
        });

        cols.push("recv".into());
        vals.push(Value::Filesize {
            val: data.total_received(),
            span,
        });

        output.push(Value::Record { cols, vals, span });
    }
    if !output.is_empty() {
        Some(Value::List { vals: output, span })
    } else {
        None
    }
}

pub fn cpu(sys: &mut System, span: Span) -> Option<Value> {
    sys.refresh_cpu();

    let mut output = vec![];
    for cpu in sys.processors() {
        let mut cols = vec![];
        let mut vals = vec![];

        cols.push("name".into());
        vals.push(Value::String {
            val: trim_cstyle_null(cpu.name().to_string()),
            span,
        });

        cols.push("brand".into());
        vals.push(Value::String {
            val: trim_cstyle_null(cpu.brand().to_string()),
            span,
        });

        cols.push("freq".into());
        vals.push(Value::Int {
            val: cpu.frequency() as i64,
            span,
        });

        output.push(Value::Record { cols, vals, span });
    }
    if !output.is_empty() {
        Some(Value::List { vals: output, span })
    } else {
        None
    }
}

pub fn mem(sys: &mut System, span: Span) -> Option<Value> {
    sys.refresh_memory();

    let mut cols = vec![];
    let mut vals = vec![];

    let total_mem = sys.total_memory();
    let free_mem = sys.free_memory();
    let total_swap = sys.total_swap();
    let free_swap = sys.free_swap();

    cols.push("total".into());
    vals.push(Value::Filesize {
        val: total_mem * 1000,
        span,
    });

    cols.push("free".into());
    vals.push(Value::Filesize {
        val: free_mem * 1000,
        span,
    });

    cols.push("swap total".into());
    vals.push(Value::Filesize {
        val: total_swap * 1000,
        span,
    });

    cols.push("swap free".into());
    vals.push(Value::Filesize {
        val: free_swap * 1000,
        span,
    });

    Some(Value::Record { cols, vals, span })
}

pub fn host(sys: &mut System, span: Span) -> Option<Value> {
    sys.refresh_users_list();

    let mut cols = vec![];
    let mut vals = vec![];

    if let Some(name) = sys.name() {
        cols.push("name".into());
        vals.push(Value::String {
            val: trim_cstyle_null(name),
            span,
        });
    }
    if let Some(version) = sys.os_version() {
        cols.push("os version".into());
        vals.push(Value::String {
            val: trim_cstyle_null(version),
            span,
        });
    }
    if let Some(version) = sys.kernel_version() {
        cols.push("kernel version".into());
        vals.push(Value::String {
            val: trim_cstyle_null(version),
            span,
        });
    }
    if let Some(hostname) = sys.host_name() {
        cols.push("hostname".into());
        vals.push(Value::String {
            val: trim_cstyle_null(hostname),
            span,
        });
    }
    cols.push("uptime".into());
    vals.push(Value::Duration {
        val: 1000000000 * sys.uptime() as u64,
        span,
    });

    let mut users = vec![];
    for user in sys.users() {
        let mut cols = vec![];
        let mut vals = vec![];

        cols.push("name".into());
        vals.push(Value::String {
            val: trim_cstyle_null(user.name().to_string()),
            span,
        });

        let mut groups = vec![];
        for group in user.groups() {
            groups.push(Value::String {
                val: trim_cstyle_null(group.to_string()),
                span,
            });
        }

        cols.push("groups".into());
        vals.push(Value::List { vals: groups, span });

        users.push(Value::Record { cols, vals, span });
    }
    if !users.is_empty() {
        cols.push("sessions".into());
        vals.push(Value::List { vals: users, span });
    }

    Some(Value::Record { cols, vals, span })
}

pub fn temp(sys: &mut System, span: Span) -> Option<Value> {
    sys.refresh_components();
    sys.refresh_components_list();

    let mut output = vec![];

    for component in sys.components() {
        let mut cols = vec![];
        let mut vals = vec![];

        cols.push("unit".into());
        vals.push(Value::String {
            val: component.label().to_string(),
            span,
        });

        cols.push("temp".into());
        vals.push(Value::Float {
            val: component.temperature() as f64,
            span,
        });

        cols.push("high".into());
        vals.push(Value::Float {
            val: component.max() as f64,
            span,
        });

        if let Some(critical) = component.critical() {
            cols.push("critical".into());
            vals.push(Value::Float {
                val: critical as f64,
                span,
            });
        }
        output.push(Value::Record { cols, vals, span });
    }
    if !output.is_empty() {
        Some(Value::List { vals: output, span })
    } else {
        None
    }
}