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

#[derive(Debug, Serialize, Deserialize, Default)]
pub struct Config {
    pub database_url: Option<String>,
}

pub fn config_dir() -> PathBuf {
    dirs::config_dir()
        .or_else(|| dirs::home_dir().map(|h| h.join(".config")))
        .unwrap_or_else(|| PathBuf::from(".config"))
        .join("secrets")
}

pub fn config_path() -> PathBuf {
    config_dir().join("config.toml")
}

pub fn load_config() -> Result<Config> {
    let path = config_path();
    if !path.exists() {
        return Ok(Config::default());
    }
    let content = fs::read_to_string(&path)
        .with_context(|| format!("failed to read config file: {}", path.display()))?;
    let config: Config = toml::from_str(&content)
        .with_context(|| format!("failed to parse config file: {}", path.display()))?;
    Ok(config)
}

pub fn save_config(config: &Config) -> Result<()> {
    let dir = config_dir();
    fs::create_dir_all(&dir)
        .with_context(|| format!("failed to create config dir: {}", dir.display()))?;

    let path = config_path();
    let content = toml::to_string_pretty(config).context("failed to serialize config")?;
    fs::write(&path, &content)
        .with_context(|| format!("failed to write config file: {}", path.display()))?;

    // Set file permissions to 0600 (owner read/write only)
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        let perms = fs::Permissions::from_mode(0o600);
        fs::set_permissions(&path, perms)
            .with_context(|| format!("failed to set file permissions: {}", path.display()))?;
    }

    Ok(())
}

/// Resolve database URL by priority:
/// 1. --db-url CLI flag (if non-empty)
/// 2. database_url in ~/.config/secrets/config.toml
/// 3. Error with setup instructions
pub fn resolve_db_url(cli_db_url: &str) -> Result<String> {
    if !cli_db_url.is_empty() {
        return Ok(cli_db_url.to_string());
    }

    let config = load_config()?;
    if let Some(url) = config.database_url
        && !url.is_empty()
    {
        return Ok(url);
    }

    anyhow::bail!("Database not configured. Run:\n\n    secrets config set-db <DATABASE_URL>\n")
}