//! Conflicting game-streaming host detection.
//!
//! Punktfunk is one of a family of Moonlight-compatible desktop-streaming hosts. The others —
//! Sunshine and its many forks (Apollo, Vibeshine, Vibepollo, LuminalShine, …) — all impersonate
//! NVIDIA GameStream: they bind the **same** ports (47984/47989 nvhttp, 47998-48010 stream,
//! 47990 web UI — which is also our management API), advertise the **same** `_nvstream._tcp`
//! mDNS service, and frequently install a **conflicting virtual-display driver**. Running one of
//! them alongside Punktfunk is unsupported — the symptoms are `address already in use` bind
//! failures, pairing that silently fails, and capture/virtual-display glitches.
//!
//! This module proactively detects such a host (installed and/or running) so we can surface it as
//! early as possible: at host startup (a `warn!` into the log ring + tray/console summary) and via
//! the `detect-conflicts` subcommand the installers/support run.
//!
//! Detection is **fingerprint-first by name**: a small table of the known products (extend
//! [`KNOWN`] as new forks appear) matched against running processes, registered OS services/units,
//! and on-disk install markers. The platform back-ends (`detect/windows.rs`, `detect/linux.rs`)
//! provide the raw facts; the matching + rendering here is portable and unit-tested.

use std::sync::OnceLock;

#[cfg(target_os = "windows")]
#[path = "detect/windows.rs"]
mod platform;
#[cfg(target_os = "linux")]
#[path = "detect/linux.rs"]
mod platform;
#[cfg(not(any(target_os = "windows", target_os = "linux")))]
mod platform {
    //! The host only runs on Windows/Linux; the crate still compiles on macOS (dev) — nothing to
    //! scan there.
    pub fn running_processes() -> Vec<String> {
        Vec::new()
    }
    pub fn static_evidence(_known: &super::Known) -> Vec<super::Evidence> {
        Vec::new()
    }
}

/// A known competing GameStream/Moonlight host.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Product {
    Sunshine,
    Apollo,
    Vibeshine,
    Vibepollo,
    Luminalshine,
}

impl Product {
    /// The name shown to the user.
    pub fn label(self) -> &'static str {
        match self {
            Product::Sunshine => "Sunshine",
            Product::Apollo => "Apollo",
            Product::Vibeshine => "Vibeshine",
            Product::Vibepollo => "Vibepollo",
            Product::Luminalshine => "LuminalShine",
        }
    }
}

/// How a conflicting host was observed on this machine.
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Evidence {
    /// A matching process is running **right now** (process/executable basename).
    Running { process: String },
    /// An OS service / systemd unit for the product is registered (installed; may be stopped).
    Service { name: String },
    /// Installed on disk — a Program Files directory, a flatpak app id, or a binary on `PATH`.
    Installed { at: String },
}

impl Evidence {
    fn render(&self) -> String {
        match self {
            Evidence::Running { process } => format!("running now ({process})"),
            Evidence::Service { name } => format!("service {name}"),
            Evidence::Installed { at } => format!("installed at {at}"),
        }
    }
}

/// A detected conflicting host, with every piece of corroborating evidence found.
#[derive(Clone, Debug)]
pub struct Detection {
    pub product: Product,
    pub evidence: Vec<Evidence>,
}

impl Detection {
    /// True when a matching process is live — the acute case (a guaranteed resource clash the
    /// moment Punktfunk tries to bind its ports).
    pub fn is_running(&self) -> bool {
        self.evidence
            .iter()
            .any(|e| matches!(e, Evidence::Running { .. }))
    }

    /// A compact one-line label for the tray/console summary, e.g. `Sunshine (running)`.
    pub fn label(&self) -> String {
        if self.is_running() {
            format!("{} (running)", self.product.label())
        } else {
            self.product.label().to_string()
        }
    }
}

/// One row of the known-conflicting-host table. Names are matched case-insensitively; process /
/// binary basenames are given **without** an extension (the platform code lowercases + strips
/// `.exe`). Extend this as new Sunshine forks appear — the runtime, the subcommand, and the
/// tray/console summary all key off this one list.
pub struct Known {
    pub product: Product,
    /// Process / executable basenames (lowercase, no extension) that identify this host.
    pub processes: &'static [&'static str],
    /// Windows service names (SCM keys under `HKLM\SYSTEM\CurrentControlSet\Services`).
    pub win_services: &'static [&'static str],
    /// Windows install-dir basenames under `%ProgramFiles%` / `%ProgramFiles(x86)%`.
    pub win_dirs: &'static [&'static str],
    /// Linux systemd unit basenames (without `.service`), checked in the standard unit dirs.
    pub linux_units: &'static [&'static str],
    /// Linux flatpak application ids.
    pub flatpaks: &'static [&'static str],
}

/// The known Moonlight-compatible hosts that clash with Punktfunk. All are Sunshine or Sunshine
/// forks; add new forks here (one row) and every surface picks them up.
pub const KNOWN: &[Known] = &[
    Known {
        product: Product::Sunshine,
        processes: &["sunshine"],
        win_services: &["SunshineService"],
        win_dirs: &["Sunshine"],
        linux_units: &["sunshine"],
        flatpaks: &["dev.lizardbyte.app.Sunshine"],
    },
    Known {
        product: Product::Apollo,
        processes: &["apollo"],
        win_services: &["ApolloService"],
        win_dirs: &["Apollo"],
        linux_units: &["apollo"],
        flatpaks: &["dev.lizardbyte.app.Apollo"],
    },
    Known {
        product: Product::Vibeshine,
        processes: &["vibeshine"],
        win_services: &["VibeshineService"],
        win_dirs: &["Vibeshine"],
        linux_units: &["vibeshine"],
        flatpaks: &[],
    },
    Known {
        product: Product::Vibepollo,
        processes: &["vibepollo"],
        win_services: &["VibepolloService"],
        win_dirs: &["Vibepollo"],
        linux_units: &["vibepollo"],
        flatpaks: &[],
    },
    Known {
        product: Product::Luminalshine,
        processes: &["luminalshine"],
        win_services: &["LuminalShineService"],
        win_dirs: &["LuminalShine"],
        linux_units: &["luminalshine"],
        flatpaks: &[],
    },
];

/// Why running side-by-side breaks — shared by every surface (log, subcommand, installers).
pub const UNSUPPORTED_BLURB: &str =
    "Running Punktfunk alongside another Moonlight-compatible host \
(Sunshine and its forks) is UNSUPPORTED: they bind the same GameStream ports (47984/47989, \
47998-48010), advertise the same _nvstream mDNS name, and often install a conflicting \
virtual-display driver. Expect \"address already in use\" errors, failed pairing, and capture \
glitches. Stop and uninstall the other host, or don't run them at the same time.";

/// Scan the machine for conflicting hosts. Portable; dispatches into the platform back-end. Does
/// real OS work (process enumeration, service/registry queries, filesystem stats) — cheap, but not
/// free, so prefer the cached [`init`]/[`snapshot`] for hot paths.
pub fn scan() -> Vec<Detection> {
    let procs = platform::running_processes();
    let mut out = Vec::new();
    for known in KNOWN {
        let mut evidence: Vec<Evidence> = Vec::new();
        for p in &procs {
            if known.processes.iter().any(|n| p == n) {
                evidence.push(Evidence::Running { process: p.clone() });
            }
        }
        evidence.extend(platform::static_evidence(known));
        if !evidence.is_empty() {
            out.push(Detection {
                product: known.product,
                evidence,
            });
        }
    }
    out
}

static SNAPSHOT: OnceLock<Vec<Detection>> = OnceLock::new();

/// Scan once and cache the result for the life of the process (the conflict set doesn't change at
/// streaming granularity — a snapshot taken at host bring-up is the right resolution and keeps the
/// per-poll `/local/summary` free). Returns the cached detections.
pub fn init() -> &'static [Detection] {
    SNAPSHOT.get_or_init(scan)
}

/// The cached snapshot, or empty if [`init`] hasn't run. Non-scanning: safe to call from hot paths
/// and from tests without touching the OS.
pub fn snapshot() -> &'static [Detection] {
    SNAPSHOT.get().map(Vec::as_slice).unwrap_or(&[])
}

/// Compact labels for the tray / web-console summary (e.g. `["Sunshine (running)", "Apollo"]`).
pub fn summary_labels(detections: &[Detection]) -> Vec<String> {
    detections.iter().map(Detection::label).collect()
}

/// A full human-readable report: the blurb + one bullet per detected host with its evidence.
/// Empty string when nothing was detected (callers gate on `is_empty()`).
pub fn render_report(detections: &[Detection]) -> String {
    if detections.is_empty() {
        return String::new();
    }
    let mut s = String::from("Detected another game-streaming host on this machine.\n");
    s.push_str(UNSUPPORTED_BLURB);
    s.push_str("\n\nDetected:\n");
    for d in detections {
        let ev = d
            .evidence
            .iter()
            .map(Evidence::render)
            .collect::<Vec<_>>()
            .join("; ");
        s.push_str(&format!("  \u{2022} {} \u{2014} {ev}\n", d.product.label()));
    }
    s
}

#[cfg(test)]
mod tests {
    use super::*;

    fn det(product: Product, evidence: Vec<Evidence>) -> Detection {
        Detection { product, evidence }
    }

    #[test]
    fn empty_report_and_labels() {
        assert!(render_report(&[]).is_empty());
        assert!(summary_labels(&[]).is_empty());
    }

    #[test]
    fn running_detection_is_flagged_and_labelled() {
        let d = det(
            Product::Sunshine,
            vec![
                Evidence::Running {
                    process: "sunshine".into(),
                },
                Evidence::Service {
                    name: "SunshineService".into(),
                },
            ],
        );
        assert!(d.is_running());
        assert_eq!(d.label(), "Sunshine (running)");
    }

    #[test]
    fn installed_only_is_not_running() {
        let d = det(
            Product::Apollo,
            vec![Evidence::Installed {
                at: "C:\\Program Files\\Apollo".into(),
            }],
        );
        assert!(!d.is_running());
        assert_eq!(d.label(), "Apollo");
    }

    #[test]
    fn report_lists_every_product_and_the_blurb() {
        let report = render_report(&[
            det(
                Product::Sunshine,
                vec![Evidence::Running {
                    process: "sunshine".into(),
                }],
            ),
            det(
                Product::Apollo,
                vec![Evidence::Installed {
                    at: "/usr/bin/apollo".into(),
                }],
            ),
        ]);
        assert!(report.contains("UNSUPPORTED"));
        assert!(report.contains("Sunshine \u{2014} running now (sunshine)"));
        assert!(report.contains("Apollo \u{2014} installed at /usr/bin/apollo"));
        assert_eq!(
            summary_labels(&[
                det(
                    Product::Sunshine,
                    vec![Evidence::Running {
                        process: "sunshine".into()
                    }]
                ),
                det(
                    Product::Apollo,
                    vec![Evidence::Installed { at: "x".into() }]
                ),
            ]),
            vec!["Sunshine (running)".to_string(), "Apollo".to_string()]
        );
    }

    #[test]
    fn known_table_rows_are_well_formed() {
        // Every known product carries at least a process name and a Windows service so the runtime
        // scan and the installer's registry check stay in agreement.
        for k in KNOWN {
            assert!(
                !k.processes.is_empty(),
                "{:?} has no process name",
                k.product
            );
            assert!(
                !k.win_services.is_empty(),
                "{:?} has no Windows service name",
                k.product
            );
        }
    }
}