use crate::storage;
use anyhow::{Context, Result};
use base64::{engine::general_purpose::URL_SAFE_NO_PAD, Engine as _};
use qrcode::{render::svg, QrCode};
use rand::{rngs::OsRng, RngCore};
use serde_json::{json, Value};
use std::{
    net::{IpAddr, Ipv4Addr, SocketAddr, UdpSocket},
    path::{Path, PathBuf},
};

#[derive(Debug, Clone)]
pub struct RuntimeConfig {
    pub config_path: PathBuf,
    pub default_bind: SocketAddr,
    pub phone_access_available: bool,
    pub ollama_enabled: bool,
    pub ollama_url: Option<String>,
    pub llama_cpp_enabled: bool,
    pub llama_cpp_url: Option<String>,
}

pub fn load_runtime_config(root: &Path, config_path: &str) -> Result<RuntimeConfig> {
    let path = if Path::new(config_path).is_absolute() {
        PathBuf::from(config_path)
    } else {
        root.join(config_path)
    };
    let text = std::fs::read_to_string(&path)
        .with_context(|| format!("cannot read config {}", path.display()))?;
    let value: toml::Value =
        toml::from_str(&text).with_context(|| format!("cannot parse config {}", path.display()))?;

    let bind_text = value
        .get("bind")
        .and_then(|v| v.as_str())
        .map(str::to_string)
        .or_else(|| {
            let host = value.get("server")?.get("host")?.as_str()?;
            let port = value.get("server")?.get("port")?.as_integer()?;
            Some(format!("{host}:{port}"))
        })
        .unwrap_or_else(|| "127.0.0.1:4891".to_string());
    let default_bind = bind_text
        .parse::<SocketAddr>()
        .with_context(|| format!("invalid bind address: {bind_text}"))?;
    let phone_access_available = value
        .get("phone_access_available")
        .and_then(|v| v.as_bool())
        .or_else(|| {
            value
                .get("security")?
                .get("phone_access_available")?
                .as_bool()
        })
        .unwrap_or(false);
    let (ollama_enabled, ollama_url) = backend_settings(&value, &["ollama"], true);
    let (llama_cpp_enabled, llama_cpp_url) =
        backend_settings(&value, &["llamacpp", "llama_cpp"], true);
    Ok(RuntimeConfig {
        config_path: path,
        default_bind,
        phone_access_available,
        ollama_enabled,
        ollama_url,
        llama_cpp_enabled,
        llama_cpp_url,
    })
}

pub fn effective_bind(root: &Path, config: &RuntimeConfig) -> SocketAddr {
    let settings = storage::read_settings(root);
    let enabled = settings
        .get("phone_access_enabled")
        .and_then(|v| v.as_bool())
        .unwrap_or(false);
    if enabled && config.phone_access_available {
        SocketAddr::new(
            IpAddr::V4(Ipv4Addr::UNSPECIFIED),
            config.default_bind.port(),
        )
    } else {
        config.default_bind
    }
}

pub fn ensure_phone_token(root: &Path) -> Result<String> {
    let mut settings = storage::read_settings(root);
    if let Some(token) = settings.get("phone_access_token").and_then(|v| v.as_str()) {
        if token.len() >= 32 {
            return Ok(token.to_string());
        }
    }
    let mut bytes = [0_u8; 24];
    OsRng.fill_bytes(&mut bytes);
    let token = URL_SAFE_NO_PAD.encode(bytes);
    if let Some(object) = settings.as_object_mut() {
        object.insert("phone_access_token".to_string(), json!(token));
    }
    storage::write_settings(root, &settings)?;
    Ok(token)
}

pub fn set_phone_access(
    root: &Path,
    config: &RuntimeConfig,
    enabled: bool,
    active_bind: SocketAddr,
) -> Result<Value> {
    if enabled && !config.phone_access_available {
        anyhow::bail!("phone access is disabled by the runtime configuration");
    }
    let mut settings = storage::read_settings(root);
    if let Some(object) = settings.as_object_mut() {
        object.insert("phone_access_enabled".to_string(), json!(enabled));
    }
    storage::write_settings(root, &settings)?;
    if enabled {
        ensure_phone_token(root)?;
    }
    Ok(status(root, config, active_bind))
}

pub fn status(root: &Path, config: &RuntimeConfig, active_bind: SocketAddr) -> Value {
    let settings = storage::read_settings(root);
    let enabled = settings
        .get("phone_access_enabled")
        .and_then(|v| v.as_bool())
        .unwrap_or(false);
    let token = settings
        .get("phone_access_token")
        .and_then(|v| v.as_str())
        .unwrap_or("");
    let active = enabled && !active_bind.ip().is_loopback();
    let local_ip = local_ipv4();
    let url = if enabled && !token.is_empty() {
        local_ip.map(|ip| format!("http://{ip}:{}?pair={token}", active_bind.port()))
    } else {
        None
    };
    let qr_svg = url.as_deref().and_then(qr_svg);
    json!({
        "available": config.phone_access_available,
        "enabled": enabled,
        "active": active,
        "bind": active_bind.to_string(),
        "url": url,
        "qr_svg": qr_svg,
        "pairing_required": true,
        "restart_required": enabled != active,
        "config": config.config_path.to_string_lossy()
    })
}

pub fn configured_token(root: &Path) -> Option<String> {
    storage::read_settings(root)
        .get("phone_access_token")
        .and_then(|v| v.as_str())
        .map(str::to_string)
}

fn local_ipv4() -> Option<Ipv4Addr> {
    let socket = UdpSocket::bind("0.0.0.0:0").ok()?;
    socket.connect("192.0.2.1:80").ok()?;
    match socket.local_addr().ok()?.ip() {
        IpAddr::V4(ip) if !ip.is_loopback() && !ip.is_unspecified() => Some(ip),
        _ => None,
    }
}

fn qr_svg(value: &str) -> Option<String> {
    let code = QrCode::new(value.as_bytes()).ok()?;
    Some(
        code.render::<svg::Color>()
            .min_dimensions(220, 220)
            .dark_color(svg::Color("#0b111a"))
            .light_color(svg::Color("#ffffff"))
            .build(),
    )
}

fn backend_settings(
    value: &toml::Value,
    names: &[&str],
    default_enabled: bool,
) -> (bool, Option<String>) {
    let backend = value
        .get("backends")
        .and_then(|backends| names.iter().find_map(|name| backends.get(*name)));
    let enabled = backend
        .and_then(|entry| entry.get("enabled"))
        .and_then(|entry| entry.as_bool())
        .unwrap_or(default_enabled);
    let url = backend
        .and_then(|entry| entry.get("url").or_else(|| entry.get("base_url")))
        .and_then(|entry| entry.as_str())
        .map(str::to_string);
    (enabled, url)
}