use anyhow::{Context, Result};
use directories::ProjectDirs;
use serde::{Deserialize, Serialize};
use std::path::PathBuf;

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Launcher {
    /// Short CLI name (e.g. "battlenet").
    pub name: String,
    /// Display name for tray / menus.
    pub display: String,
    /// Wine prefix directory for this launcher.
    pub prefix_dir: PathBuf,
    /// Path to the launcher exe, relative to the prefix's drive_c/.
    pub exe_path: PathBuf,
    /// umu GAMEID (used to look up protonfixes).
    pub gameid: String,
    /// pgrep/pkill -f regex matching this launcher's running processes.
    pub process_pattern: String,
    /// Optional URL of the Windows installer (consumed by `setup`).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub installer_url: Option<String>,
    /// Optional per-launcher Proton version override (falls back to
    /// Config::proton_version).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub proton_version: Option<String>,
}

impl Launcher {
    /// Absolute path to the launcher exe inside the prefix.
    pub fn full_exe_path(&self) -> PathBuf {
        self.prefix_dir.join("drive_c").join(&self.exe_path)
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Config {
    /// Directory where GE-Proton versions are installed.
    #[serde(default = "default_compat_dir")]
    pub proton_compat_dir: PathBuf,
    /// Default Proton version passed to PROTONPATH.
    /// The literal "GE-Proton" makes umu-run fetch/use the latest.
    #[serde(default = "default_proton_version")]
    pub proton_version: String,
    /// Configured launchers.
    #[serde(default)]
    pub launchers: Vec<Launcher>,
}

fn home_dir() -> PathBuf {
    std::env::var("HOME")
        .map(PathBuf::from)
        .expect("$HOME is not set; cannot determine default paths")
}

fn default_compat_dir() -> PathBuf {
    home_dir().join(".local/share/Steam/compatibilitytools.d")
}

fn default_proton_version() -> String {
    "GE-Proton".into()
}

fn regex_escape(s: &str) -> String {
    let mut out = String::with_capacity(s.len() + 4);
    for c in s.chars() {
        if matches!(
            c,
            '.' | '*' | '?' | '+' | '(' | ')' | '[' | ']'
                | '{' | '}' | '|' | '\\' | '^' | '$'
        ) {
            out.push('\\');
        }
        out.push(c);
    }
    out
}

/// The six launchers umutray ships out of the box. `exe_path`, `gameid`,
/// and `process_pattern` are best-effort defaults for typical installs —
/// users can adjust per-launcher via `umutray config edit`.
pub fn presets() -> Vec<Launcher> {
    let games = home_dir().join("Games");
    vec![
        Launcher {
            name: "battlenet".into(),
            display: "Battle.net".into(),
            prefix_dir: games.join("battlenet"),
            exe_path: PathBuf::from(
                "Program Files (x86)/Battle.net/Battle.net Launcher.exe",
            ),
            gameid: "umu-battlenet".into(),
            process_pattern: r"Battle\.net".into(),
            installer_url: None,
            proton_version: None,
        },
        Launcher {
            name: "eaapp".into(),
            display: "EA App".into(),
            prefix_dir: games.join("eaapp"),
            exe_path: PathBuf::from(
                "Program Files/Electronic Arts/EA Desktop/EA Desktop/EADesktop.exe",
            ),
            gameid: "umu-eaapp".into(),
            process_pattern: r"EADesktop\.exe".into(),
            installer_url: None,
            proton_version: None,
        },
        Launcher {
            name: "epic".into(),
            display: "Epic Games".into(),
            prefix_dir: games.join("epic"),
            exe_path: PathBuf::from(
                "Program Files (x86)/Epic Games/Launcher/Portal/Binaries/Win32/EpicGamesLauncher.exe",
            ),
            gameid: "umu-epicgameslauncher".into(),
            process_pattern: r"EpicGamesLauncher\.exe".into(),
            installer_url: None,
            proton_version: None,
        },
        Launcher {
            name: "ubisoft".into(),
            display: "Ubisoft Connect".into(),
            prefix_dir: games.join("ubisoft"),
            exe_path: PathBuf::from(
                "Program Files (x86)/Ubisoft/Ubisoft Game Launcher/UbisoftConnect.exe",
            ),
            gameid: "umu-uplay".into(),
            process_pattern: r"UbisoftConnect\.exe|upc\.exe".into(),
            installer_url: None,
            proton_version: None,
        },
        Launcher {
            name: "gog".into(),
            display: "GOG Galaxy".into(),
            prefix_dir: games.join("gog"),
            exe_path: PathBuf::from(
                "Program Files (x86)/GOG Galaxy/GalaxyClient.exe",
            ),
            gameid: "umu-gog".into(),
            process_pattern: r"GalaxyClient\.exe".into(),
            installer_url: None,
            proton_version: None,
        },
        Launcher {
            name: "rockstar".into(),
            display: "Rockstar Games".into(),
            prefix_dir: games.join("rockstar"),
            exe_path: PathBuf::from(
                "Program Files/Rockstar Games/Launcher/Launcher.exe",
            ),
            gameid: "umu-rockstar".into(),
            process_pattern: r"Rockstar Games.*Launcher\.exe".into(),
            installer_url: None,
            proton_version: None,
        },
    ]
}

impl Default for Config {
    fn default() -> Self {
        Self {
            proton_compat_dir: default_compat_dir(),
            proton_version: default_proton_version(),
            launchers: presets(),
        }
    }
}

impl Config {
    pub fn config_path() -> Result<PathBuf> {
        let dirs = ProjectDirs::from("co.aleshym", "", "umutray")
            .context("Could not determine config directory")?;
        Ok(dirs.config_dir().join("config.toml"))
    }

    pub fn load() -> Result<Self> {
        let path = Self::config_path()?;
        if !path.exists() {
            let c = Self::default();
            c.save().context("Failed to write default config")?;
            return Ok(c);
        }
        let content = std::fs::read_to_string(&path)
            .with_context(|| format!("Failed to read config from {path:?}"))?;
        match toml::from_str::<Self>(&content) {
            Ok(mut c) => {
                if c.launchers.is_empty() {
                    c.launchers = presets();
                    c.save().context("Failed to write presets")?;
                }
                Ok(c)
            }
            Err(e) => {
                let bak = path.with_extension("toml.bak");
                std::fs::rename(&path, &bak).with_context(|| {
                    format!("Failed to back up stale config to {bak:?}")
                })?;
                eprintln!("warning: couldn't parse {}: {e}", path.display());
                eprintln!(
                    "         backed up to {} — writing fresh config with presets",
                    bak.display()
                );
                let c = Self::default();
                c.save()?;
                Ok(c)
            }
        }
    }

    pub fn save(&self) -> Result<()> {
        let path = Self::config_path()?;
        if let Some(parent) = path.parent() {
            std::fs::create_dir_all(parent)?;
        }
        let content = toml::to_string_pretty(self)?;
        std::fs::write(&path, content)
            .with_context(|| format!("Failed to write config to {path:?}"))
    }

    pub fn find(&self, name: &str) -> Option<&Launcher> {
        self.launchers.iter().find(|l| l.name == name)
    }

    pub fn show(&self) -> Result<()> {
        let path = Self::config_path()?;
        println!("# {}", path.display());
        let s = toml::to_string_pretty(self)?;
        print!("{s}");
        Ok(())
    }

    pub fn edit() -> Result<()> {
        let _ = Self::load()?;
        let path = Self::config_path()?;
        let editor = std::env::var("EDITOR")
            .or_else(|_| std::env::var("VISUAL"))
            .unwrap_or_else(|_| "nano".into());
        let status = std::process::Command::new(&editor)
            .arg(&path)
            .status()
            .with_context(|| format!("Failed to spawn editor '{editor}'"))?;
        if !status.success() {
            anyhow::bail!("Editor '{editor}' exited non-zero");
        }
        Ok(())
    }

    #[allow(clippy::too_many_arguments)]
    pub fn add_launcher(
        &mut self,
        name: String,
        display: Option<String>,
        exe_path: PathBuf,
        prefix_dir: Option<PathBuf>,
        gameid: Option<String>,
        process_pattern: Option<String>,
        installer_url: Option<String>,
    ) -> Result<()> {
        if self.launchers.iter().any(|l| l.name == name) {
            anyhow::bail!("launcher '{name}' already exists");
        }
        let display = display.unwrap_or_else(|| name.clone());
        let prefix_dir = prefix_dir
            .unwrap_or_else(|| home_dir().join("Games").join(&name));
        let gameid = gameid.unwrap_or_else(|| format!("umu-{name}"));
        let process_pattern = process_pattern.unwrap_or_else(|| {
            exe_path
                .file_name()
                .and_then(|s| s.to_str())
                .map(regex_escape)
                .unwrap_or_else(|| name.clone())
        });
        self.launchers.push(Launcher {
            name: name.clone(),
            display,
            prefix_dir,
            exe_path,
            gameid,
            process_pattern,
            installer_url,
            proton_version: None,
        });
        self.save()?;
        println!("\x1b[1;32m✓\x1b[0m Added launcher '{name}'.");
        Ok(())
    }

    pub fn remove_launcher(&mut self, name: &str) -> Result<()> {
        let before = self.launchers.len();
        self.launchers.retain(|l| l.name != name);
        if self.launchers.len() == before {
            anyhow::bail!("no launcher named '{name}'");
        }
        self.save()?;
        println!(
            "\x1b[1;32m✓\x1b[0m Removed '{name}'. \
             The Wine prefix on disk was left untouched."
        );
        Ok(())
    }

    /// Update global fields non-interactively, then save.
    /// Use `config edit` for per-launcher changes.
    pub fn set_globals(
        &mut self,
        proton_version: Option<String>,
        compat_dir: Option<PathBuf>,
    ) -> Result<()> {
        if proton_version.is_none() && compat_dir.is_none() {
            anyhow::bail!(
                "nothing to set — pass --proton-version or --compat-dir"
            );
        }
        if let Some(v) = proton_version {
            self.proton_version = v;
        }
        if let Some(d) = compat_dir {
            self.proton_compat_dir = d;
        }
        self.save()?;
        println!("\x1b[1;32m✓\x1b[0m Config saved.");
        println!();
        self.show()
    }
}