use serde::{Deserialize, Serialize};
use anyhow::Result;
use std::fs;
use std::path::PathBuf;

#[derive(Debug, Deserialize, Serialize, Clone)]
pub struct Config {
    pub server_url: String,
    pub timeout_sec: u64,
    #[serde(default = "default_theme")]
    pub theme: Theme,
    #[serde(default)]
    pub update_api: Option<String>,
}

#[derive(Debug, Deserialize, Serialize, Clone)]
pub struct Theme {
    #[serde(default = "default_selected_bg")]
    pub selected_bg: String,
}

fn default_selected_bg() -> String {
    "blue".to_string()
}

fn default_theme() -> Theme {
    Theme {
        selected_bg: default_selected_bg(),
    }
}

pub fn config_path() -> PathBuf {
    // Respect XDG_CONFIG_HOME; fall back to ~/.config on all platforms.
    let base = std::env::var("XDG_CONFIG_HOME")
        .map(PathBuf::from)
        .unwrap_or_else(|_| {
            dirs::home_dir()
                .unwrap_or_else(|| PathBuf::from("."))
                .join(".config")
        });
    base.join(env!("CARGO_PKG_NAME")).join("config.toml")
}

impl Config {
    /// Returns true when a config file already exists.
    pub fn exists() -> bool {
        config_path().exists()
    }

    /// Load config from disk. Panics-safe: returns error if file is missing or malformed.
    pub fn load() -> Result<Self> {
        let path = config_path();
        let content = fs::read_to_string(&path)?;
        Ok(toml::from_str(&content)?)
    }

    /// Create and persist a new config with the given server URL.
    pub fn create_with_url(server_url: &str) -> Result<Self> {
        let path = config_path();
        let config = Config {
            server_url: server_url.to_string(),
            timeout_sec: 10,
            theme: default_theme(),
            update_api: None,
        };
        fs::create_dir_all(path.parent().unwrap())?;
        fs::write(&path, toml::to_string_pretty(&config)?)?;
        Ok(config)
    }
}