use crate::theme::Settings;
use std::path::Path;

const SETTINGS_FILE: &str = "settings.json";

pub fn settings_dir() -> std::path::PathBuf {
    if let Ok(exe) = std::env::current_exe() {
        if let Some(dir) = exe.parent() {
            return dir.to_path_buf();
        }
    }
    std::path::PathBuf::from(".")
}

pub fn save_settings(dir: &Path, settings: &Settings) -> Result<(), String> {
    let path = dir.join(SETTINGS_FILE);
    let json = serde_json::to_string_pretty(settings)
        .map_err(|e| format!("序列化设置失败: {}", e))?;
    std::fs::write(&path, json)
        .map_err(|e| format!("保存设置失败: {}", e))?;
    Ok(())
}

pub fn load_settings(dir: &Path) -> Result<Settings, String> {
    let path = dir.join(SETTINGS_FILE);
    let json = std::fs::read_to_string(&path)
        .map_err(|e| format!("读取设置失败: {}", e))?;
    let mut settings: Settings = serde_json::from_str(&json)
        .map_err(|e| format!("解析设置失败: {}", e))?;
    // Always refresh profiles from code-defined presets so that updated
    // preset values (font size, spacing, etc.) take effect even when
    // an older settings.json is present on disk.
    let preset_names: Vec<String> = crate::style::StyleProfile::presets()
        .iter()
        .map(|p| p.name.clone())
        .collect();
    settings.profiles = crate::style::StyleProfile::presets();
    if !preset_names.contains(&settings.active_profile) {
        settings.active_profile = "Kindle 默认".into();
    }
    Ok(settings)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::theme::{Settings, Theme};

    #[test]
    fn test_save_and_load_settings() {
        let dir = std::env::temp_dir().join("epub-read-test");
        let _ = std::fs::create_dir_all(&dir);

        let mut s = Settings::default();
        s.font_size = 24.0;
        s.theme = Theme::Dark;
        save_settings(&dir, &s).unwrap();

        let loaded = load_settings(&dir).unwrap();
        assert_eq!(loaded.font_size, 24.0);
        assert_eq!(loaded.theme, Theme::Dark);

        let _ = std::fs::remove_dir_all(&dir);
    }

    #[test]
    fn test_load_settings_nonexistent() {
        let dir = std::env::temp_dir().join("epub-read-test-nonexistent");
        let _ = std::fs::remove_dir_all(&dir);
        let result = load_settings(&dir);
        assert!(result.is_err());
    }
}