//! Per-CPU plugin.

use crate::cpu_percent::cpu_percent;
use crate::fields;
use glances_core::plugin::{Field, Plugin, PluginModel, UpdateContext};
use glances_core::{Args, Config};
use serde_json::Value;

pub struct PerCpuPlugin {
    pub model: PluginModel,
    pub max_cpu_display: usize,
}

impl PerCpuPlugin {
    pub fn new(config: &Config, args: &Args) -> Self {
        let fields = fields! {
            "cpu_number" => Field::new("CPU number"),
            "total" => Field::new("Sum of CPU percentages (except idle) for current CPU number.").unit("percent"),
            "system" => Field::new("Percent time spent in kernel space. System CPU time is the time spent running code in the Operating System kernel.").unit("percent"),
            "user" => Field::new("CPU percent time spent in user space. User CPU time is the time spent on the processor running your program's code (or code in libraries).").unit("percent"),
            "iowait" => Field::new("*(Linux)*: percent time spent by the CPU waiting for I/O operations to complete.").unit("percent"),
            "idle" => Field::new("percent of CPU used by any program. Every program or task that runs on a computer system occupies a certain amount of processing time on the CPU. If the CPU has completed all tasks it is idle.").unit("percent"),
            "irq" => Field::new("*(Linux and BSD)*: percent time spent servicing/handling hardware/software interrupts. Time servicing interrupts (hardware + software).").unit("percent"),
            "nice" => Field::new("*(Unix)*: percent time occupied by user level processes with a positive nice value. The time the CPU has spent running users' processes that are *niced*.").unit("percent"),
            "steal" => Field::new("*(Linux)*: percentage of time a virtual CPU waits for a real CPU while the hypervisor is servicing another virtual processor.").unit("percent"),
            "guest" => Field::new("*(Linux)*: percent of time spent running a virtual CPU for guest operating systems under the control of the Linux kernel.").unit("percent"),
            "guest_nice" => Field::new("*(Linux)*: percent of time spent running a niced guest (virtual CPU).").unit("percent"),
            "softirq" => Field::new("*(Linux)*: percent of time spent handling software interrupts.").unit("percent"),
            "dpc" => Field::new("*(Windows)*: percent of time spent handling deferred procedure calls.").unit("percent"),
            "interrupt" => Field::new("*(Windows)*: percent of time spent handling software interrupts.").unit("percent"),
        };
        let mut model = PluginModel::new(
            "percpu",
            fields,
            Vec::new(),
            Value::Array(Vec::new()),
            config,
            args.time.unwrap_or(2.0),
            args.disable_history,
            args.disable_config_exec,
        );
        model.set_item_key("cpu_number");
        let max_cpu_display = config.get_int_value("percpu", "max_cpu_display", 4).max(1) as usize;
        Self { model, max_cpu_display }
    }
}

impl Plugin for PerCpuPlugin {
    fn name(&self) -> &str {
        "percpu"
    }

    fn model(&self) -> &PluginModel {
        &self.model
    }

    fn model_mut(&mut self) -> &mut PluginModel {
        &mut self.model
    }

    fn get_key(&self) -> Option<&'static str> {
        Some("cpu_number")
    }

    fn collect(&mut self, _ctx: &mut UpdateContext) -> anyhow::Result<Value> {
        let mut state = cpu_percent().lock().unwrap();
        Ok(Value::Array(state.get_percpu().to_vec()))
    }

    fn render(&mut self, ctx: &glances_core::RenderContext) -> Vec<glances_core::StatLine> {
        let mut ret = Vec::new();
        let items: Vec<Value> = self.model.stats.as_array().cloned().unwrap_or_default();
        if items.is_empty() || !ctx.runtime.percpu {
            return ret;
        }
        let items = &items;
        let quicklook_disabled = !ctx.runtime.is_plugin_enabled("quicklook");
        let mut header = vec!["user", "system", "iowait", "idle", "irq", "nice", "steal", "guest"];
        if quicklook_disabled {
            ret.push(self.model.curse_add_line(format!("{:5}", "CPU"), glances_core::Decoration::Title, false, false, false));
            header.insert(0, "total");
        }
        for stat in &header {
            ret.push(self.model.curse_add_line(format!("{stat:>7}"), glances_core::Decoration::Default, false, false, false));
        }
        // Sort by total and keep the top max_cpu_display cores.
        let mut sorted: Vec<Value> = items.clone();
        if sorted.len() > self.max_cpu_display {
            sorted.sort_by(|a, b| {
                b.get("total")
                    .and_then(Value::as_f64)
                    .unwrap_or(0.0)
                    .partial_cmp(&a.get("total").and_then(Value::as_f64).unwrap_or(0.0))
                    .unwrap_or(std::cmp::Ordering::Equal)
            });
        }
        let displayed: Vec<Value> = sorted.iter().take(self.max_cpu_display).cloned().collect();
        for cpu in &displayed {
            ret.push(self.model.curse_new_line());
            if quicklook_disabled {
                let cpu_id = cpu.get("cpu_number").and_then(Value::as_i64).unwrap_or(0);
                let msg = if cpu_id < 10 { format!("CPU{cpu_id:1} ") } else { format!("{cpu_id:4} ") };
                ret.push(self.model.curse_add_line(msg, glances_core::Decoration::Default, false, false, false));
            }
            for stat in &header {
                let value = cpu.get(*stat).and_then(Value::as_f64);
                let decoration = match value {
                    Some(value) => self.model.get_alert(value, 0.0, 100.0, true, false, Some(stat), None, false),
                    None => glances_core::Decoration::Default,
                };
                let msg = match value {
                    Some(value) => format!("{value:6.1}%"),
                    None => format!("{:>6}%", "?"),
                };
                ret.push(self.model.curse_add_line(msg, decoration, false, false, false));
            }
        }
        if items.len() > self.max_cpu_display {
            ret.push(self.model.curse_new_line());
            if quicklook_disabled {
                ret.push(self.model.curse_add_line("CPU* ", glances_core::Decoration::Default, false, false, false));
            }
            for stat in &header {
                let values: Vec<f64> = sorted
                    .iter()
                    .skip(self.max_cpu_display)
                    .filter_map(|cpu| cpu.get(*stat).and_then(Value::as_f64))
                    .collect();
                let mean = if values.is_empty() { 0.0 } else { values.iter().sum::<f64>() / values.len() as f64 };
                let decoration = self.model.get_alert(mean, 0.0, 100.0, true, false, Some(stat), None, false);
                ret.push(self.model.curse_add_line(format!("{mean:6.1}%"), decoration, false, false, false));
            }
        }
        ret
    }
}