use axum::{
    extract::Query,
    http::{header, StatusCode},
    response::{Html, IntoResponse},
    routing::get,
    Router,
};
use qr_core::qr::{QrCode, QrConfig, VersionMode};
use qr_core::version::EcLevel;
use serde::Deserialize;

/// GET /api/qr 查询参数
#[derive(Deserialize)]
struct QrParams {
    text: String,
    #[serde(default = "default_level")]
    level: String,
    #[serde(default = "default_margin")]
    margin: u8,
    #[serde(default = "default_size")]
    size: u8,
    /// fmt=svg 返回 SVG，否则返回 PNG
    #[serde(default)]
    fmt: String,
}

fn default_level() -> String {
    "M".into()
}
fn default_margin() -> u8 {
    4
}
fn default_size() -> u8 {
    8
}

fn parse_level(s: &str) -> Result<EcLevel, String> {
    match s.to_uppercase().as_str() {
        "L" => Ok(EcLevel::L),
        "M" => Ok(EcLevel::M),
        "Q" => Ok(EcLevel::Q),
        "H" => Ok(EcLevel::H),
        _ => Err(format!("无效纠错级别: {}，支持 L/M/Q/H", s)),
    }
}

/// 首页 HTML（编译期嵌入）
async fn index() -> Html<&'static str> {
    Html(include_str!("templates/index.html"))
}

/// QR 码生成 API → PNG 或 SVG
async fn generate_qr(Query(params): Query<QrParams>) -> impl IntoResponse {
    let level = match parse_level(&params.level) {
        Ok(l) => l,
        Err(e) => return (StatusCode::BAD_REQUEST, e).into_response(),
    };

    let config = QrConfig {
        level,
        version: VersionMode::Auto,
        margin: params.margin,
    };

    let qr = match QrCode::encode(&params.text, config) {
        Ok(q) => q,
        Err(e) => return (StatusCode::BAD_REQUEST, e).into_response(),
    };

    if params.fmt == "svg" {
        let svg = qr.to_svg();
        ([(header::CONTENT_TYPE, "image/svg+xml")], svg).into_response()
    } else {
        match qr.to_png_bytes(params.size) {
            Ok(b) => ([(header::CONTENT_TYPE, "image/png")], b).into_response(),
            Err(e) => (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()).into_response(),
        }
    }
}

#[tokio::main]
async fn main() {
    let app = Router::new()
        .route("/", get(index))
        .route("/api/qr", get(generate_qr));

    let addr = "0.0.0.0:3000";
    println!("QRGen Web → http://{}", addr);

    let listener = tokio::net::TcpListener::bind(addr).await.unwrap();
    axum::serve(listener, app).await.unwrap();
}