modde_games/

detection.rs

//! Unified game detection across Steam and Heroic launchers.
//!
//! Scans all known launcher libraries and returns every detected game
//! installation, including launcher metadata. This allows the UI and CLI
//! to present a "pick your game" experience without manual path entry.

use std::path::{Path, PathBuf};
use std::process::{Command, ExitStatus, Stdio};

use anyhow::{Context, Result};
use serde_json::Value;
use tracing::{debug, info, warn};

use modde_core::paths;

/// A game installation detected by scanning launcher libraries.
#[derive(Debug, Clone)]
pub struct DetectedGame {
    /// The modde game_id (e.g. "skyrim-se", "cyberpunk2077").
    pub game_id: &'static str,
    /// Human-readable display name.
    pub display_name: &'static str,
    /// Absolute path to the game's install directory.
    pub install_path: PathBuf,
    /// Which launcher owns this installation.
    pub source: LauncherSource,
}

/// Which launcher/store a detected game belongs to.
#[derive(Debug, Clone)]
pub enum LauncherSource {
    Steam {
        app_id: String,
        library_path: PathBuf,
    },
    HeroicGog {
        app_id: String,
    },
    HeroicEpic {
        app_id: String,
    },
    HeroicSideload {
        app_id: String,
    },
}

impl LauncherSource {
    fn label_and_id(&self) -> (&str, &str) {
        match self {
            LauncherSource::Steam { app_id, .. } => ("Steam", app_id),
            LauncherSource::HeroicGog { app_id } => ("Heroic/GOG", app_id),
            LauncherSource::HeroicEpic { app_id } => ("Heroic/Epic", app_id),
            LauncherSource::HeroicSideload { app_id } => ("Heroic/Sideload", app_id),
        }
    }

    /// Launch the game via its detected launcher.
    ///
    /// Returns `Ok(Some(ExitStatus))` if we could wait for the game process to exit
    /// (Heroic), or `Ok(None)` for fire-and-forget launchers (Steam).
    pub fn launch(&self) -> Result<Option<ExitStatus>> {
        match self {
            LauncherSource::Steam { app_id, .. } => {
                let url = format!("steam://rungameid/{app_id}");
                info!(%url, "launching via Steam");
                open::that(&url)
                    .with_context(|| format!("failed to launch Steam via URI ({url})"))?;
                Ok(None)
            }
            LauncherSource::HeroicGog { app_id }
            | LauncherSource::HeroicEpic { app_id }
            | LauncherSource::HeroicSideload { app_id } => {
                let (bin, base_args) = heroic_command()
                    .context("Heroic Games Launcher not found (checked flatpak and PATH)")?;
                info!(%bin, %app_id, "launching via Heroic");
                let mut cmd = Command::new(&bin);
                for arg in &base_args {
                    cmd.arg(arg);
                }
                let status = cmd
                    .args(["--no-gui", "--launch", app_id])
                    .status()
                    .with_context(|| format!("failed to launch Heroic ({bin} --no-gui --launch {app_id})"))?;
                Ok(Some(status))
            }
        }
    }
}

impl std::fmt::Display for LauncherSource {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let (label, id) = self.label_and_id();
        write!(f, "{label} ({id})")
    }
}

/// Known game identifiers for matching against launcher databases.
///
/// Each entry maps a modde `game_id` to the IDs used by various launchers.
struct KnownGame {
    game_id: &'static str,
    display_name: &'static str,
    /// Steam app ID (None if not on Steam).
    steam_app_id: Option<&'static str>,
    /// Steam directory name under `steamapps/common/`.
    steam_dir: Option<&'static str>,
    /// GOG app ID for Heroic (None if not on GOG).
    gog_app_id: Option<&'static str>,
    /// Epic/Legendary app name (None if not on Epic).
    epic_app_id: Option<&'static str>,
}

/// Registry of all known games and their launcher identifiers.
const KNOWN_GAMES: &[KnownGame] = &[
    KnownGame {
        game_id: "skyrim-se",
        display_name: "The Elder Scrolls V: Skyrim Special Edition",
        steam_app_id: Some("489830"),
        steam_dir: Some("Skyrim Special Edition"),
        gog_app_id: None,
        epic_app_id: None,
    },
    // AE shares the same Steam dir as SE — detected as skyrim-se by default.
    // Users can override to skyrim-ae in settings.
    KnownGame {
        game_id: "fallout4",
        display_name: "Fallout 4",
        steam_app_id: Some("377160"),
        steam_dir: Some("Fallout 4"),
        gog_app_id: Some("1998527297"),
        epic_app_id: None,
    },
    KnownGame {
        game_id: "fallout76",
        display_name: "Fallout 76",
        steam_app_id: Some("1151340"),
        steam_dir: Some("Fallout76"),
        gog_app_id: None,
        epic_app_id: None,
    },
    KnownGame {
        game_id: "starfield",
        display_name: "Starfield",
        steam_app_id: Some("1716740"),
        steam_dir: Some("Starfield"),
        gog_app_id: None,
        epic_app_id: None,
    },
    KnownGame {
        game_id: "cyberpunk2077",
        display_name: "Cyberpunk 2077",
        steam_app_id: Some("1091500"),
        steam_dir: Some("Cyberpunk 2077"),
        gog_app_id: Some("1423049311"),
        epic_app_id: Some("Ginger"),
    },
    KnownGame {
        game_id: "stellar-blade",
        display_name: "Stellar Blade",
        steam_app_id: Some("3489700"),
        // Steam installs under `steamapps/common/Stellar Blade` — if your
        // install uses the trademark glyph ("Stellar Blade™"), update this.
        steam_dir: Some("Stellar Blade"),
        gog_app_id: None,
        epic_app_id: None,
    },
];

/// Detect the Heroic Games Launcher binary.
///
/// - Linux: checks flatpak first, then native binary on `$PATH`
/// - macOS: checks `/Applications/Heroic.app`, then `$PATH`
/// - Windows: checks standard install path, then `%PATH%`
///
/// Returns `(binary, base_args)` — e.g. `("flatpak", ["run", "com.heroicgameslauncher.hgl"])`
/// or `("heroic", [])`.
fn heroic_command() -> Option<(String, Vec<String>)> {
    #[cfg(target_os = "linux")]
    {
        // Check flatpak first (common on NixOS / immutable distros)
        if Command::new("flatpak")
            .args(["info", "com.heroicgameslauncher.hgl"])
            .stdout(Stdio::null())
            .stderr(Stdio::null())
            .status()
            .ok()
            .map(|s| s.success())
            .unwrap_or(false)
        {
            return Some((
                "flatpak".to_string(),
                vec!["run".to_string(), "com.heroicgameslauncher.hgl".to_string()],
            ));
        }

        // Check native binary on PATH
        if let Ok(path) = which::which("heroic") {
            return Some((path.to_string_lossy().to_string(), vec![]));
        }

        None
    }

    #[cfg(target_os = "macos")]
    {
        let app_path = "/Applications/Heroic.app/Contents/MacOS/Heroic";
        if std::path::Path::new(app_path).exists() {
            return Some((app_path.to_string(), vec![]));
        }
        if let Ok(path) = which::which("heroic") {
            return Some((path.to_string_lossy().to_string(), vec![]));
        }
        None
    }

    #[cfg(target_os = "windows")]
    {
        if let Some(exe) = modde_core::paths::heroic_exe_path() {
            return Some((exe.to_string_lossy().to_string(), vec![]));
        }
        if let Ok(path) = which::which("heroic") {
            return Some((path.to_string_lossy().to_string(), vec![]));
        }
        None
    }
}

/// Find a detected game by its modde game_id.
///
/// Convenience wrapper around [`scan_installed_games`] that returns the first
/// match. Used by both CLI and UI to resolve the launcher for a game.
pub fn find_detected_game(game_id: &str) -> Option<DetectedGame> {
    scan_installed_games()
        .into_iter()
        .find(|g| g.game_id == game_id)
}

/// Scan all known launchers for installed games.
///
/// Returns every detected game with its install path and launcher source.
/// A game may appear multiple times if installed via different launchers.
pub fn scan_installed_games() -> Vec<DetectedGame> {
    let mut detected = Vec::new();

    scan_steam_libraries(&mut detected);
    scan_heroic_stores(&mut detected);

    detected
}

/// Scan all Steam library folders for known games.
fn scan_steam_libraries(detected: &mut Vec<DetectedGame>) {
    let libraries = paths::steam_library_folders();

    for lib_path in &libraries {
        let common_dir = lib_path.join("steamapps/common");
        if !common_dir.is_dir() {
            continue;
        }

        for game in KNOWN_GAMES {
            let Some(steam_dir) = game.steam_dir else {
                continue;
            };

            let install_path = common_dir.join(steam_dir);
            if install_path.is_dir() {
                debug!(
                    game_id = game.game_id,
                    path = %install_path.display(),
                    "detected Steam game"
                );
                detected.push(DetectedGame {
                    game_id: game.game_id,
                    display_name: game.display_name,
                    install_path,
                    source: LauncherSource::Steam {
                        app_id: game.steam_app_id.unwrap_or("unknown").to_string(),
                        library_path: lib_path.clone(),
                    },
                });
            }
        }
    }
}

/// Scan Heroic's installed game databases (GOG, Epic/Legendary, Sideload).
fn scan_heroic_stores(detected: &mut Vec<DetectedGame>) {
    let Some(heroic_dir) = paths::heroic_config_dir() else {
        return;
    };

    // GOG store
    scan_heroic_store_file(
        &heroic_dir.join("gog_store/installed.json"),
        |app_id| {
            KNOWN_GAMES
                .iter()
                .find(|g| g.gog_app_id == Some(app_id))
                .map(|g| (g, HeroicStoreKind::Gog))
        },
        detected,
    );

    // Epic/Legendary store
    scan_heroic_store_file(
        &heroic_dir.join("legendary_store/installed.json"),
        |app_id| {
            KNOWN_GAMES
                .iter()
                .find(|g| g.epic_app_id == Some(app_id))
                .map(|g| (g, HeroicStoreKind::Epic))
        },
        detected,
    );

    // Sideloaded apps — match by directory name heuristic
    scan_heroic_sideload(&heroic_dir.join("sideload_apps/installed.json"), detected);
}

#[derive(Clone, Copy)]
enum HeroicStoreKind {
    Gog,
    Epic,
}

/// Parse a Heroic `installed.json` and match entries against known games.
fn scan_heroic_store_file(
    path: &Path,
    matcher: impl Fn(&str) -> Option<(&KnownGame, HeroicStoreKind)>,
    detected: &mut Vec<DetectedGame>,
) {
    let data = match std::fs::read_to_string(path) {
        Ok(d) => d,
        Err(e) => {
            debug!(error = %e, path = %path.display(), "failed to read Heroic store file");
            return;
        }
    };

    let parsed: Value = match serde_json::from_str(&data) {
        Ok(v) => v,
        Err(e) => {
            warn!(error = %e, path = %path.display(), "failed to parse Heroic store JSON");
            return;
        }
    };

    let Some(installed) = parsed.get("installed").and_then(|v| v.as_array()) else {
        debug!(path = %path.display(), "Heroic store file missing 'installed' array");
        return;
    };

    for entry in installed {
        let Some(app_name) = entry.get("appName").and_then(|v| v.as_str()) else {
            continue;
        };
        let Some(install_path) = entry.get("install_path").and_then(|v| v.as_str()) else {
            continue;
        };

        let install_path = PathBuf::from(install_path);
        if !install_path.is_dir() {
            continue;
        }

        if let Some((game, kind)) = matcher(app_name) {
            debug!(
                game_id = game.game_id,
                app_name,
                path = %install_path.display(),
                "detected Heroic game"
            );
            let source = match kind {
                HeroicStoreKind::Gog => LauncherSource::HeroicGog {
                    app_id: game.gog_app_id.unwrap_or(app_name).to_string(),
                },
                HeroicStoreKind::Epic => LauncherSource::HeroicEpic {
                    app_id: game.epic_app_id.unwrap_or(app_name).to_string(),
                },
            };
            detected.push(DetectedGame {
                game_id: game.game_id,
                display_name: game.display_name,
                install_path,
                source,
            });
        }
    }
}

/// Scan Heroic sideloaded apps — match by directory name against known steam_dir names.
fn scan_heroic_sideload(path: &Path, detected: &mut Vec<DetectedGame>) {
    let data = match std::fs::read_to_string(path) {
        Ok(d) => d,
        Err(e) => {
            debug!(error = %e, path = %path.display(), "failed to read Heroic sideload file");
            return;
        }
    };

    let parsed: Value = match serde_json::from_str(&data) {
        Ok(v) => v,
        Err(e) => {
            warn!(error = %e, path = %path.display(), "failed to parse Heroic sideload JSON");
            return;
        }
    };

    let Some(installed) = parsed.get("installed").and_then(|v| v.as_array()) else {
        debug!(path = %path.display(), "Heroic sideload file missing 'installed' array");
        return;
    };

    for entry in installed {
        let Some(app_name) = entry.get("appName").and_then(|v| v.as_str()) else {
            continue;
        };
        let Some(install_path_str) = entry.get("install_path").and_then(|v| v.as_str()) else {
            continue;
        };

        let install_path = PathBuf::from(install_path_str);
        if !install_path.is_dir() {
            continue;
        }

        // Try to match by directory name
        let dir_name = install_path
            .file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("");

        for game in KNOWN_GAMES {
            let matches = game
                .steam_dir
                .map(|sd| sd.eq_ignore_ascii_case(dir_name))
                .unwrap_or(false);

            if matches {
                debug!(
                    game_id = game.game_id,
                    app_name,
                    path = %install_path.display(),
                    "detected Heroic sideloaded game"
                );
                detected.push(DetectedGame {
                    game_id: game.game_id,
                    display_name: game.display_name,
                    install_path,
                    source: LauncherSource::HeroicSideload {
                        app_id: app_name.to_string(),
                    },
                });
                break;
            }
        }
    }
}

/// Find the install path for a specific game by scanning all launchers.
///
/// This is used by `GamePlugin::detect_install()` implementations to check
/// all available sources instead of just hardcoded paths.
pub fn find_game_install(game_id: &str) -> Option<PathBuf> {
    // Check settings override first
    let settings = modde_core::settings::AppSettings::load();
    if let Some(path) = settings.game_path(game_id) {
        if path.is_dir() {
            return Some(path.clone());
        }
    }

    // Scan all launchers
    scan_installed_games()
        .into_iter()
        .find(|g| g.game_id == game_id)
        .map(|g| g.install_path)
}

#[cfg(test)]
mod tests {
    use super::*;
    // ── Heroic store file parsing ─────────────────────────────────────

    fn write_heroic_installed(dir: &std::path::Path, entries: &[(&str, &str)]) {
        let items: Vec<serde_json::Value> = entries
            .iter()
            .map(|(app_name, install_path)| {
                serde_json::json!({
                    "appName": app_name,
                    "install_path": install_path,
                })
            })
            .collect();
        let json = serde_json::json!({ "installed": items });
        std::fs::write(dir, serde_json::to_string(&json).unwrap()).unwrap();
    }

    #[test]
    fn scan_heroic_gog_detects_known_game() {
        let tmp = tempfile::tempdir().unwrap();
        let install_dir = tmp.path().join("cyberpunk");
        std::fs::create_dir_all(&install_dir).unwrap();

        let store_file = tmp.path().join("installed.json");
        write_heroic_installed(&store_file, &[("1423049311", &install_dir.to_string_lossy())]);

        let mut detected = Vec::new();
        scan_heroic_store_file(
            &store_file,
            |app_id| {
                KNOWN_GAMES
                    .iter()
                    .find(|g| g.gog_app_id == Some(app_id))
                    .map(|g| (g, HeroicStoreKind::Gog))
            },
            &mut detected,
        );

        assert_eq!(detected.len(), 1);
        assert_eq!(detected[0].game_id, "cyberpunk2077");
        assert_eq!(detected[0].install_path, install_dir);
        assert!(matches!(detected[0].source, LauncherSource::HeroicGog { .. }));
    }

    #[test]
    fn scan_heroic_gog_unknown_game_ignored() {
        let tmp = tempfile::tempdir().unwrap();
        let install_dir = tmp.path().join("some_game");
        std::fs::create_dir_all(&install_dir).unwrap();

        let store_file = tmp.path().join("installed.json");
        write_heroic_installed(&store_file, &[("9999999999", &install_dir.to_string_lossy())]);

        let mut detected = Vec::new();
        scan_heroic_store_file(
            &store_file,
            |app_id| {
                KNOWN_GAMES
                    .iter()
                    .find(|g| g.gog_app_id == Some(app_id))
                    .map(|g| (g, HeroicStoreKind::Gog))
            },
            &mut detected,
        );

        assert_eq!(detected.len(), 0, "unknown game should not be added");
    }

    #[test]
    fn scan_heroic_nonexistent_install_path_skipped() {
        let tmp = tempfile::tempdir().unwrap();
        let store_file = tmp.path().join("installed.json");
        // Path does not exist on disk
        write_heroic_installed(&store_file, &[("1423049311", "/nonexistent/cyberpunk")]);

        let mut detected = Vec::new();
        scan_heroic_store_file(
            &store_file,
            |app_id| {
                KNOWN_GAMES
                    .iter()
                    .find(|g| g.gog_app_id == Some(app_id))
                    .map(|g| (g, HeroicStoreKind::Gog))
            },
            &mut detected,
        );

        assert_eq!(detected.len(), 0, "nonexistent install path should be skipped");
    }

    #[test]
    fn scan_heroic_missing_file_is_no_op() {
        let mut detected = Vec::new();
        // Should not panic
        scan_heroic_store_file(
            std::path::Path::new("/nonexistent/installed.json"),
            |_| None,
            &mut detected,
        );
        assert_eq!(detected.len(), 0);
    }

    #[test]
    fn scan_heroic_malformed_json_is_no_op() {
        let tmp = tempfile::tempdir().unwrap();
        let store_file = tmp.path().join("installed.json");
        std::fs::write(&store_file, "this is not json").unwrap();

        let mut detected = Vec::new();
        scan_heroic_store_file(
            &store_file,
            |_| None,
            &mut detected,
        );
        assert_eq!(detected.len(), 0);
    }

    #[test]
    fn scan_heroic_empty_installed_array() {
        let tmp = tempfile::tempdir().unwrap();
        let store_file = tmp.path().join("installed.json");
        std::fs::write(&store_file, r#"{"installed":[]}"#).unwrap();

        let mut detected = Vec::new();
        scan_heroic_store_file(
            &store_file,
            |_| None,
            &mut detected,
        );
        assert_eq!(detected.len(), 0);
    }

    #[test]
    fn scan_heroic_sideload_matches_by_dirname() {
        let tmp = tempfile::tempdir().unwrap();
        // Create a dir named like the Cyberpunk Steam dir
        let install_dir = tmp.path().join("Cyberpunk 2077");
        std::fs::create_dir_all(&install_dir).unwrap();

        let store_file = tmp.path().join("installed.json");
        write_heroic_installed(&store_file, &[("some_sideload_id", &install_dir.to_string_lossy())]);

        let mut detected = Vec::new();
        scan_heroic_sideload(&store_file, &mut detected);

        assert_eq!(detected.len(), 1);
        assert_eq!(detected[0].game_id, "cyberpunk2077");
        assert!(matches!(detected[0].source, LauncherSource::HeroicSideload { .. }));
    }

    #[test]
    fn scan_heroic_sideload_unknown_dirname_ignored() {
        let tmp = tempfile::tempdir().unwrap();
        let install_dir = tmp.path().join("Some Unknown Game 2077");
        std::fs::create_dir_all(&install_dir).unwrap();

        let store_file = tmp.path().join("installed.json");
        write_heroic_installed(&store_file, &[("some_id", &install_dir.to_string_lossy())]);

        let mut detected = Vec::new();
        scan_heroic_sideload(&store_file, &mut detected);

        assert_eq!(detected.len(), 0);
    }

    // ── Steam library scanning ────────────────────────────────────────

    #[test]
    fn scan_steam_libraries_detects_game_in_common() {
        let tmp = tempfile::tempdir().unwrap();
        // Create a fake Steam library with "Cyberpunk 2077" in steamapps/common/
        let common = tmp.path().join("steamapps/common/Cyberpunk 2077");
        std::fs::create_dir_all(&common).unwrap();

        // Temporarily override HOME to point to our temp dir so steam_library_folders works
        // Instead, we directly test scan_steam_libraries by injecting a mock path.
        // We can do this by patching the paths module — but since we can't do that easily,
        // we test via the internal helper by constructing the detection directly.
        let detected_game = KNOWN_GAMES.iter().find(|g| g.game_id == "cyberpunk2077").unwrap();
        let install_path = common.clone();
        assert_eq!(install_path.file_name().unwrap(), "Cyberpunk 2077");
        assert!(install_path.is_dir());
        // If we had a real Steam library here, scan_steam_libraries would find this.
        // This is a structural test asserting KNOWN_GAMES has the right steam_dir.
        assert_eq!(detected_game.steam_dir, Some("Cyberpunk 2077"));
    }

    // ── LauncherSource display ────────────────────────────────────────

    #[test]
    fn launcher_source_display_steam() {
        let src = LauncherSource::Steam {
            app_id: "1091500".to_string(),
            library_path: PathBuf::from("/games"),
        };
        assert_eq!(src.to_string(), "Steam (1091500)");
    }

    #[test]
    fn launcher_source_display_heroic_gog() {
        let src = LauncherSource::HeroicGog { app_id: "1423049311".to_string() };
        assert_eq!(src.to_string(), "Heroic/GOG (1423049311)");
    }

    #[test]
    fn launcher_source_display_heroic_epic() {
        let src = LauncherSource::HeroicEpic { app_id: "Ginger".to_string() };
        assert_eq!(src.to_string(), "Heroic/Epic (Ginger)");
    }

    #[test]
    fn launcher_source_display_sideload() {
        let src = LauncherSource::HeroicSideload { app_id: "custom_app".to_string() };
        assert_eq!(src.to_string(), "Heroic/Sideload (custom_app)");
    }

    // ── KNOWN_GAMES integrity ─────────────────────────────────────────

    #[test]
    fn known_games_ids_are_unique() {
        let ids: Vec<_> = KNOWN_GAMES.iter().map(|g| g.game_id).collect();
        let deduped: std::collections::HashSet<_> = ids.iter().collect();
        assert_eq!(ids.len(), deduped.len(), "KNOWN_GAMES has duplicate game_ids");
    }

    #[test]
    fn known_games_includes_supported_games() {
        use crate::SUPPORTED_GAME_IDS;
        for &game_id in SUPPORTED_GAME_IDS.iter()
            .filter(|g| **g != "skyrim-ae")  // AE intentionally shares SE's steam dir
        {
            if ["skyrim-se", "fallout4", "cyberpunk2077"].contains(&game_id) {
                assert!(
                    KNOWN_GAMES.iter().any(|g| g.game_id == game_id),
                    "KNOWN_GAMES missing {game_id}"
                );
            }
        }
    }
}