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

use super::database::AppImageRecord;

#[derive(Debug)]
pub enum IntegrationError {
    IoError(std::io::Error),
    NoAppName,
}

impl std::fmt::Display for IntegrationError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::IoError(e) => write!(f, "I/O error: {}", e),
            Self::NoAppName => write!(f, "Cannot integrate: no application name"),
        }
    }
}

impl From<std::io::Error> for IntegrationError {
    fn from(e: std::io::Error) -> Self {
        Self::IoError(e)
    }
}

/// Escape a string for use inside a double-quoted Exec argument in a .desktop file.
/// Per the Desktop Entry spec, `\`, `"`, `` ` ``, and `$` must be escaped with `\`.
fn escape_exec_arg(s: &str) -> String {
    let mut out = String::with_capacity(s.len());
    for c in s.chars() {
        match c {
            '\\' | '"' | '`' | '$' => {
                out.push('\\');
                out.push(c);
            }
            _ => out.push(c),
        }
    }
    out
}

pub struct IntegrationResult {
    pub desktop_file_path: PathBuf,
    pub icon_install_path: Option<PathBuf>,
}

fn applications_dir() -> PathBuf {
    crate::config::data_dir_fallback()
        .join("applications")
}

fn icons_dir() -> PathBuf {
    crate::config::data_dir_fallback()
        .join("icons/hicolor")
}

/// Generate a sanitized app ID.
pub fn make_app_id(app_name: &str) -> String {
    let id: String = app_name
        .chars()
        .map(|c| {
            if c.is_alphanumeric() || c == '-' || c == '_' {
                c.to_ascii_lowercase()
            } else {
                '-'
            }
        })
        .collect();
    id.trim_matches('-').to_string()
}

/// Integrate an AppImage: create .desktop file and install icon.
pub fn integrate(record: &AppImageRecord) -> Result<IntegrationResult, IntegrationError> {
    let app_name = record
        .app_name
        .as_deref()
        .or(Some(&record.filename))
        .ok_or(IntegrationError::NoAppName)?;

    let app_id = make_app_id(app_name);
    let desktop_filename = format!("driftwood-{}.desktop", app_id);

    let apps_dir = applications_dir();
    fs::create_dir_all(&apps_dir)?;

    let desktop_path = apps_dir.join(&desktop_filename);

    // Build the .desktop file content
    let categories = record
        .categories
        .as_deref()
        .unwrap_or("");
    let comment = record
        .description
        .as_deref()
        .unwrap_or("");
    let version = record
        .app_version
        .as_deref()
        .unwrap_or("");
    let now = chrono::Utc::now().format("%Y-%m-%d %H:%M:%S").to_string();

    let icon_id = format!("driftwood-{}", app_id);

    let desktop_content = format!("\
[Desktop Entry]
Type=Application
Name={name}
Exec=\"{exec}\" %U
Icon={icon}
Categories={categories}
Comment={comment}
Terminal=false
X-AppImage-Path={path}
X-AppImage-Version={version}
X-AppImage-Managed-By=Driftwood
X-AppImage-Integrated-Date={date}
",
        name = app_name,
        exec = escape_exec_arg(&record.path),
        icon = icon_id,
        categories = categories,
        comment = comment,
        path = record.path,
        version = version,
        date = now,
    );

    fs::write(&desktop_path, &desktop_content)?;

    // Install icon if we have a cached one
    let icon_install_path = if let Some(ref cached_icon) = record.icon_path {
        let cached = Path::new(cached_icon);
        if cached.exists() {
            install_icon(cached, &icon_id)?
        } else {
            None
        }
    } else {
        None
    };

    // Update desktop database (best effort)
    update_desktop_database();

    Ok(IntegrationResult {
        desktop_file_path: desktop_path,
        icon_install_path,
    })
}

/// Install an icon to the hicolor icon theme directory.
fn install_icon(source: &Path, icon_id: &str) -> Result<Option<PathBuf>, IntegrationError> {
    let ext = source
        .extension()
        .and_then(|e| e.to_str())
        .unwrap_or("png");

    let (subdir, filename) = if ext == "svg" {
        ("scalable/apps", format!("{}.svg", icon_id))
    } else {
        ("256x256/apps", format!("{}.png", icon_id))
    };

    let dest_dir = icons_dir().join(subdir);
    fs::create_dir_all(&dest_dir)?;
    let dest = dest_dir.join(&filename);
    fs::copy(source, &dest)?;

    Ok(Some(dest))
}

/// Remove integration for an AppImage.
pub fn remove_integration(record: &AppImageRecord) -> Result<(), IntegrationError> {
    let app_name = record
        .app_name
        .as_deref()
        .or(Some(&record.filename))
        .ok_or(IntegrationError::NoAppName)?;

    let app_id = make_app_id(app_name);

    // Remove .desktop file
    if let Some(ref desktop_file) = record.desktop_file {
        let path = Path::new(desktop_file);
        if path.exists() {
            fs::remove_file(path)?;
        }
    } else {
        // Try the conventional path
        let desktop_path = applications_dir().join(format!("driftwood-{}.desktop", app_id));
        if desktop_path.exists() {
            fs::remove_file(&desktop_path)?;
        }
    }

    // Remove icon files
    let icon_id = format!("driftwood-{}", app_id);
    remove_icon_files(&icon_id);

    update_desktop_database();

    Ok(())
}

fn remove_icon_files(icon_id: &str) {
    let base = icons_dir();
    let candidates = [
        base.join(format!("256x256/apps/{}.png", icon_id)),
        base.join(format!("scalable/apps/{}.svg", icon_id)),
        base.join(format!("128x128/apps/{}.png", icon_id)),
        base.join(format!("48x48/apps/{}.png", icon_id)),
    ];
    for path in &candidates {
        if path.exists() {
            fs::remove_file(path).ok();
        }
    }
}

fn update_desktop_database() {
    let apps_dir = applications_dir();
    Command::new("update-desktop-database")
        .arg(&apps_dir)
        .stdout(std::process::Stdio::null())
        .stderr(std::process::Stdio::null())
        .status()
        .ok();
}

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

    #[test]
    fn test_make_app_id() {
        assert_eq!(make_app_id("Firefox"), "firefox");
        assert_eq!(make_app_id("My Cool App"), "my-cool-app");
        assert_eq!(make_app_id("  Spaces  "), "spaces");
    }

    #[test]
    fn test_integrate_creates_desktop_file() {
        let _dir = tempfile::tempdir().unwrap();
        // Override the applications dir for testing by creating the record
        // with a specific path and testing the desktop content generation
        let record = AppImageRecord {
            id: 1,
            path: "/home/user/Apps/Firefox.AppImage".to_string(),
            filename: "Firefox.AppImage".to_string(),
            app_name: Some("Firefox".to_string()),
            app_version: Some("124.0".to_string()),
            appimage_type: Some(2),
            size_bytes: 100_000_000,
            sha256: None,
            icon_path: None,
            desktop_file: None,
            integrated: false,
            integrated_at: None,
            is_executable: true,
            desktop_entry_content: None,
            categories: Some("Network;WebBrowser".to_string()),
            description: Some("Web Browser".to_string()),
            developer: None,
            architecture: Some("x86_64".to_string()),
            first_seen: "2026-01-01".to_string(),
            last_scanned: "2026-01-01".to_string(),
            file_modified: None,
            fuse_status: None,
            wayland_status: None,
            update_info: None,
            update_type: None,
            latest_version: None,
            update_checked: None,
            update_url: None,
            notes: None,
            sandbox_mode: None,
            runtime_wayland_status: None,
            runtime_wayland_checked: None,
            analysis_status: None,
            launch_args: None,
            tags: None,
            pinned: false,
            avg_startup_ms: None,
            appstream_id: None,
            appstream_description: None,
            generic_name: None,
            license: None,
            homepage_url: None,
            bugtracker_url: None,
            donation_url: None,
            help_url: None,
            vcs_url: None,
            keywords: None,
            mime_types: None,
            content_rating: None,
            project_group: None,
            release_history: None,
            desktop_actions: None,
            has_signature: false,
            screenshot_urls: None,
        };

        // We can't easily test the full integrate() without mocking dirs,
        // but we can verify make_app_id and the desktop content format
        let app_id = make_app_id(record.app_name.as_deref().unwrap());
        assert_eq!(app_id, "firefox");
        assert_eq!(format!("driftwood-{}.desktop", app_id), "driftwood-firefox.desktop");
    }
}