//! System information collectors
//!
//! Each module is responsible for collecting a specific category
//! of system information in a platform-agnostic way.

pub mod command;
pub mod cpu;
pub mod disk;
pub mod memory;
pub mod network;
pub mod os;
pub mod platform;
pub mod session;

use crate::error::Result;

/// Controls how much data to collect
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CollectMode {
    /// Full collection — all fields, all subprocess calls
    Full,
    /// Fast collection — skip slow platform-specific collectors for quick auto-run
    Fast,
}

/// Collected system information used by TR-300 reports
#[derive(Debug, Clone)]
pub struct SystemInfo {
    // OS Section
    pub os_name: String,
    pub os_version: String,
    pub kernel: String,
    pub architecture: String,
    pub machine_model: Option<String>,

    // Network Section
    pub hostname: String,
    pub machine_ip: Option<String>,
    pub client_ip: Option<String>,
    pub dns_servers: Vec<String>,
    pub username: String,

    // CPU Section
    pub processor: String,
    pub cores: usize,
    pub sockets: Option<usize>,
    pub hypervisor: Option<String>,
    pub cpu_freq_ghz: f64,
    pub load_1m: Option<f64>,
    pub load_5m: Option<f64>,
    pub load_15m: Option<f64>,
    pub gpus: Vec<String>,
    pub cpu_core_topology: Option<String>,

    // Disk Section
    pub disk_used_bytes: u64,
    pub disk_total_bytes: u64,
    pub disk_percent: f64,
    pub zfs_health: Option<String>,

    // Memory Section
    pub mem_used_bytes: u64,
    pub mem_total_bytes: u64,
    pub mem_percent: f64,
    pub motherboard: Option<String>,
    pub bios: Option<String>,
    pub ram_slots: Option<String>,

    // Session Section
    pub last_login: Option<String>,
    pub last_login_ip: Option<String>,
    pub uptime_seconds: u64,
    /// Current kernel-session uptime when distinct from `uptime_seconds`
    /// (Windows Fast Startup case). `None` otherwise — drives the
    /// `UPTIME … (session: …)` annotation when `Some(_)`.
    pub session_uptime_seconds: Option<u64>,
    pub shell: Option<String>,
    pub terminal: Option<String>,
    pub locale: Option<String>,
    pub battery: Option<String>,
    pub encryption: Option<String>,

    /// The collection mode used
    pub mode: CollectMode,

    /// Whether the current process is running with elevated privileges
    /// (Unix euid == 0 / Windows admin token under UAC). Drives the
    /// elevation-tier footer hint and gates admin-only collectors.
    pub is_elevated: bool,
}

impl SystemInfo {
    /// Collect all system information with the given mode.
    /// Uses `std::thread::scope` to run collectors in parallel —
    /// the 200ms CPU sleep (full mode) overlaps with disk/network/session/platform.
    pub fn collect_with_mode(mode: CollectMode) -> Result<Self> {
        use crate::error::AppError;

        let (os_info, cpu_info, mem_info, disks, net_info, session_info, platform_info) =
            std::thread::scope(|s| {
                let os_h = s.spawn(|| os::collect(mode));
                let cpu_h = s.spawn(|| cpu::collect(mode));
                let mem_h = s.spawn(memory::collect);
                let disk_h = s.spawn(disk::collect);
                let net_h = s.spawn(|| network::collect_network_info(mode));
                let session_h = s.spawn(|| session::collect(mode));
                let platform_h = s.spawn(|| platform::collect(mode));

                (
                    os_h.join().unwrap_or_else(|_| {
                        Err(AppError::system_info("OS collector thread panicked"))
                    }),
                    cpu_h.join().unwrap_or_else(|_| {
                        Err(AppError::system_info("CPU collector thread panicked"))
                    }),
                    mem_h.join().unwrap_or_else(|_| {
                        Err(AppError::system_info("memory collector thread panicked"))
                    }),
                    disk_h.join().unwrap_or_else(|_| {
                        Err(AppError::system_info("disk collector thread panicked"))
                    }),
                    net_h.join().unwrap_or_else(|_| {
                        Err(AppError::system_info("network collector thread panicked"))
                    }),
                    session_h.join().unwrap_or_else(|_| {
                        Err(AppError::system_info("session collector thread panicked"))
                    }),
                    platform_h
                        .join()
                        .unwrap_or_else(|_| platform::PlatformInfo::default()),
                )
            });

        let os_info = os_info?;
        let cpu_info = cpu_info?;
        let mem_info = mem_info?;
        let disks = disks?;
        let net_info = net_info?;
        let session_info = session_info?;

        // Aggregate disk info (use root/C: or sum all)
        let (disk_used, disk_total) = aggregate_disk_usage(&disks);
        let disk_percent = if disk_total > 0 {
            (disk_used as f64 / disk_total as f64) * 100.0
        } else {
            0.0
        };

        // Memory percentage
        let mem_percent = if mem_info.total_bytes > 0 {
            (mem_info.used_bytes as f64 / mem_info.total_bytes as f64) * 100.0
        } else {
            0.0
        };

        // Hypervisor detection
        let hypervisor = platform_info.virtualization.or_else(|| {
            if mode == CollectMode::Full {
                Some("Bare Metal".to_string())
            } else {
                None
            }
        });

        Ok(Self {
            os_name: os_info.name,
            os_version: os_info.version,
            kernel: os_info.kernel_version,
            architecture: platform_info
                .architecture
                .unwrap_or_else(|| std::env::consts::ARCH.to_string()),
            machine_model: platform_info.machine_model,
            hostname: os_info.hostname,
            machine_ip: net_info.machine_ip,
            client_ip: net_info.client_ip,
            dns_servers: net_info.dns_servers,
            username: session_info.username,
            processor: cpu_info.brand,
            cores: cpu_info.logical_cores,
            sockets: cpu_info.sockets,
            hypervisor,
            cpu_freq_ghz: cpu_info.frequency_mhz as f64 / 1000.0,
            load_1m: cpu_info.load_1m,
            load_5m: cpu_info.load_5m,
            load_15m: cpu_info.load_15m,
            gpus: platform_info.gpus,
            cpu_core_topology: platform_info.cpu_core_topology,
            disk_used_bytes: disk_used,
            disk_total_bytes: disk_total,
            disk_percent,
            zfs_health: platform_info.zfs_health,
            mem_used_bytes: mem_info.used_bytes,
            mem_total_bytes: mem_info.total_bytes,
            mem_percent,
            motherboard: platform_info.motherboard,
            bios: platform_info.bios,
            ram_slots: platform_info.ram_slots,
            last_login: session_info.last_login,
            last_login_ip: session_info.last_login_ip,
            uptime_seconds: os_info.uptime_seconds,
            session_uptime_seconds: os_info.session_uptime_seconds,
            shell: platform_info.shell,
            terminal: platform_info.terminal,
            locale: platform_info.locale,
            battery: platform_info.battery,
            encryption: platform_info.encryption,
            mode,
            is_elevated: crate::is_elevated(),
        })
    }

    /// Collect all system information (full mode, backward compatible)
    pub fn collect() -> Result<Self> {
        Self::collect_with_mode(CollectMode::Full)
    }

    /// Format uptime as human-readable string. When `session_uptime_seconds`
    /// is set (Windows Fast Startup case where the kernel session is shorter
    /// than the cold-boot time), appends a `(session: …)` annotation.
    pub fn uptime_formatted(&self) -> String {
        let primary = format_duration_seconds(self.uptime_seconds);
        match self.session_uptime_seconds {
            Some(s) => format!("{} (session: {})", primary, format_duration_seconds(s)),
            None => primary,
        }
    }

    /// Format bytes as GB
    pub fn format_gb(bytes: u64) -> String {
        let gb = bytes as f64 / (1024.0 * 1024.0 * 1024.0);
        format!("{:.2}", gb)
    }

    /// Format bytes as GiB (for memory)
    pub fn format_gib(bytes: u64) -> String {
        let gib = bytes as f64 / (1024.0 * 1024.0 * 1024.0);
        format!("{:.2}", gib)
    }

    /// Get disk usage string for table output
    pub fn disk_usage_str(&self) -> String {
        format!(
            "{}/{} GB [{:.2}%]",
            Self::format_gb(self.disk_used_bytes),
            Self::format_gb(self.disk_total_bytes),
            self.disk_percent
        )
    }

    /// Get memory usage string for table output
    pub fn memory_usage_str(&self) -> String {
        format!(
            "{}/{} GiB [{:.1}%]",
            Self::format_gib(self.mem_used_bytes),
            Self::format_gib(self.mem_total_bytes),
            self.mem_percent
        )
    }

    /// Get cores string for table output
    pub fn cores_str(&self) -> String {
        if let Some(sockets) = self.sockets {
            format!("{} vCPU(s) / {} Socket(s)", self.cores, sockets)
        } else {
            format!("{} vCPU(s)", self.cores)
        }
    }

    /// Get CPU frequency string
    pub fn freq_str(&self) -> String {
        format!("{:.1} GHz", self.cpu_freq_ghz)
    }
}

/// Format a seconds count as a compact "Nd Nh Nm" / "Nh Nm" / "Nm" string.
fn format_duration_seconds(secs: u64) -> String {
    let days = secs / 86400;
    let hours = (secs % 86400) / 3600;
    let minutes = (secs % 3600) / 60;
    if days > 0 {
        format!("{}d {}h {}m", days, hours, minutes)
    } else if hours > 0 {
        format!("{}h {}m", hours, minutes)
    } else {
        format!("{}m", minutes)
    }
}

/// Aggregate disk usage - prioritize root/C: drive, or sum all non-removable
fn aggregate_disk_usage(disks: &[disk::DiskInfo]) -> (u64, u64) {
    // Try to find the root or C: drive
    for d in disks {
        // v3.15.8: tightened the C: match from `starts_with("C:")` to an
        // exact case-insensitive comparison so a junction-mounted
        // directory at e.g. `C:\mnt\D` doesn't wrongly match as if it
        // were the C: root. (audit finding F18)
        if d.mount_point == "/"
            || d.mount_point.eq_ignore_ascii_case("c:\\")
            || d.mount_point.eq_ignore_ascii_case("c:")
        {
            return (d.used_bytes, d.total_bytes);
        }
    }

    // Otherwise sum all non-removable disks
    let mut total_used = 0u64;
    let mut total_size = 0u64;
    for d in disks {
        if !d.is_removable {
            total_used = total_used.saturating_add(d.used_bytes);
            total_size = total_size.saturating_add(d.total_bytes);
        }
    }

    if total_size == 0 && !disks.is_empty() {
        // Fallback to first disk
        (disks[0].used_bytes, disks[0].total_bytes)
    } else {
        (total_used, total_size)
    }
}
