use crate::config::{Config, Launcher};
use anyhow::Result;
use owo_colors::OwoColorize;
use std::os::unix::fs::MetadataExt;
use std::path::Path;
use std::process::{Command, Stdio};

#[derive(Debug, Clone)]
pub struct CheckResult {
    pub label: String,
    pub pass: bool,
    pub detail: String,
}

impl CheckResult {
    fn pass(label: impl Into<String>, detail: impl Into<String>) -> Self {
        Self { label: label.into(), pass: true, detail: detail.into() }
    }
    fn fail(label: impl Into<String>, detail: impl Into<String>) -> Self {
        Self { label: label.into(), pass: false, detail: detail.into() }
    }
}

pub fn run_checks(config: &Config, name: Option<&str>) -> Result<Vec<CheckResult>> {
    let mut checks = vec![
        global_umu_check(),
        global_vulkan_check(),
        global_display_check(),
        compat_dir_check(config),
        wineserver_check(config),
    ];
    let launchers: Vec<&Launcher> = if let Some(n) = name {
        let l = config
            .find(n)
            .ok_or_else(|| anyhow::anyhow!("unknown launcher '{n}'"))?;
        vec![l]
    } else {
        config.launchers.iter().collect()
    };
    for l in launchers {
        checks.extend(launcher_checks(l));
    }
    Ok(checks)
}

pub fn run(config: &Config, name: Option<&str>) -> Result<()> {
    let checks = run_checks(config, name)?;
    let mut issues = 0u32;
    println!();
    for c in &checks {
        if !c.pass {
            issues += 1;
        }
        if c.pass {
            println!("  {} {:24} {}", "✓".green().bold(), c.label, c.detail);
        } else {
            println!("  {} {:24} {}", "✗".red().bold(), c.label, c.detail);
        }
    }
    println!();
    if issues == 0 {
        println!("  {}", "All checks passed.".green().bold());
    } else {
        println!("  {}", format!("{issues} issue(s) found — see ✗ items above.").red().bold());
    }
    println!();
    Ok(())
}

fn global_umu_check() -> CheckResult {
    match which("umu-run") {
        Some(p) => CheckResult::pass("umu-run", format!("found at {p}")),
        None => CheckResult::fail("umu-run", "not found — install umu-launcher"),
    }
}

fn global_vulkan_check() -> CheckResult {
    let ok = Command::new("vulkaninfo")
        .arg("--summary")
        .stdout(Stdio::null())
        .stderr(Stdio::null())
        .status()
        .map(|s| s.success())
        .unwrap_or(false);
    if ok {
        CheckResult::pass("vulkan", "vulkaninfo OK")
    } else {
        CheckResult::fail(
            "vulkan",
            "vulkaninfo failed — check GPU drivers / vulkan-tools",
        )
    }
}

fn global_display_check() -> CheckResult {
    let display = std::env::var("DISPLAY").ok();
    let wayland = std::env::var("WAYLAND_DISPLAY").ok();
    match (display, wayland) {
        (Some(d), Some(_)) => CheckResult::pass("display", format!("XWayland (DISPLAY={d})")),
        (Some(d), None) => CheckResult::pass("display", format!("X11 (DISPLAY={d})")),
        (None, Some(_)) => CheckResult::fail(
            "display",
            "Wayland session but DISPLAY unset; XWayland needed",
        ),
        (None, None) => CheckResult::fail("display", "neither DISPLAY nor WAYLAND_DISPLAY set"),
    }
}

fn compat_dir_check(config: &Config) -> CheckResult {
    let n = count_ge_proton(&config.proton_compat_dir);
    if config.proton_version == "GE-Proton" {
        CheckResult::pass(
            "proton",
            format!(
                "tracking latest; {n} version(s) in {}",
                config.proton_compat_dir.display()
            ),
        )
    } else {
        let path = config.proton_compat_dir.join(&config.proton_version);
        if path.exists() {
            CheckResult::pass("proton", format!("{} installed", config.proton_version))
        } else {
            CheckResult::fail(
                "proton",
                format!(
                    "{} missing — run: umutray update-proton --version={}",
                    config.proton_version, config.proton_version
                ),
            )
        }
    }
}

fn wineserver_check(config: &Config) -> CheckResult {
    let count = wineserver_count();
    if count == 0 {
        return CheckResult::pass("wine procs", "no wineserver running");
    }
    let any_running = config.launchers.iter().any(crate::launcher::is_running);
    if any_running {
        CheckResult::pass(
            "wine procs",
            format!("{count} wineserver process(es); launcher active"),
        )
    } else {
        CheckResult::fail(
            "wine procs",
            format!("{count} stale wineserver process(es) — try: umutray kill"),
        )
    }
}

fn wineserver_count() -> usize {
    Command::new("pgrep")
        .args(["-c", "-f", "wineserver"])
        .output()
        .ok()
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .and_then(|s| s.trim().parse::<usize>().ok())
        .unwrap_or(0)
}

fn launcher_checks(l: &Launcher) -> Vec<CheckResult> {
    let mut out = Vec::new();
    let tag = format!("[{}]", l.name);

    if !l.prefix_dir.exists() {
        out.push(CheckResult::fail(
            format!("{tag} prefix"),
            format!(
                "{} missing — run: umutray setup {}",
                l.prefix_dir.display(),
                l.name
            ),
        ));
        return out;
    }
    out.push(CheckResult::pass(
        format!("{tag} prefix"),
        l.prefix_dir.display().to_string(),
    ));

    let exe = l.full_exe_path();
    if exe.exists() {
        out.push(CheckResult::pass(format!("{tag} exe"), "installed"));
    } else {
        out.push(CheckResult::fail(
            format!("{tag} exe"),
            format!("missing — run: umutray setup {}", l.name),
        ));
    }

    if is_owned_by_current_user(&l.prefix_dir) {
        out.push(CheckResult::pass(format!("{tag} owner"), "owned by current user"));
    } else {
        out.push(CheckResult::fail(
            format!("{tag} owner"),
            "not owned by current user",
        ));
    }

    if crate::launcher::is_running(l) {
        out.push(CheckResult::pass(format!("{tag} process"), "currently running"));
    } else {
        out.push(CheckResult::pass(format!("{tag} process"), "not running"));
    }

    out
}

fn count_ge_proton(dir: &Path) -> usize {
    std::fs::read_dir(dir)
        .ok()
        .map(|entries| {
            entries
                .filter_map(|e| e.ok())
                .filter(|e| {
                    e.file_name()
                        .to_str()
                        .map(|s| s.starts_with("GE-Proton"))
                        .unwrap_or(false)
                })
                .count()
        })
        .unwrap_or(0)
}

fn which(cmd: &str) -> Option<String> {
    Command::new("which")
        .arg(cmd)
        .output()
        .ok()
        .filter(|o| o.status.success())
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .map(|s| s.trim().to_string())
}

fn is_owned_by_current_user(path: &Path) -> bool {
    let file_uid = match std::fs::metadata(path) {
        Ok(m) => m.uid(),
        Err(_) => return true,
    };
    let current_uid: Option<u32> = Command::new("id")
        .arg("-u")
        .output()
        .ok()
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .and_then(|s| s.trim().parse().ok());
    match current_uid {
        Some(uid) => uid == file_uid,
        None => true,
    }
}