//! Nostr relay management: configure, monitor, and manage relay connections.

use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::path::Path;
use tokio::fs;
use tracing::debug;

const RELAYS_FILE: &str = "nostr_relays.json";

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RelayConfig {
    pub url: String,
    pub enabled: bool,
    pub added_at: String,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RelayStatus {
    pub url: String,
    pub connected: bool,
    pub enabled: bool,
    pub added_at: String,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct RelayStore {
    pub relays: Vec<RelayConfig>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RelayStats {
    pub total_relays: usize,
    pub connected_count: usize,
    pub enabled_count: usize,
}

/// Default relays seeded on first use.
const DEFAULT_RELAYS: &[&str] = &[
    "wss://relay.damus.io",
    "wss://nos.lol",
    "wss://relay.nostr.band",
    "wss://relay.snort.social",
    "wss://nostr.wine",
    "wss://relay.nostr.info",
    "wss://nostr-pub.wellorder.net",
    "wss://relay.current.fyi",
];

pub async fn load_relays(data_dir: &Path) -> Result<RelayStore> {
    let path = data_dir.join(RELAYS_FILE);
    if !path.exists() {
        // Seed with defaults on first load
        let store = seed_defaults();
        save_relays(data_dir, &store).await?;
        return Ok(store);
    }
    let data = fs::read_to_string(&path)
        .await
        .context("Reading relay store")?;
    serde_json::from_str(&data).context("Parsing relay store")
}

pub async fn save_relays(data_dir: &Path, store: &RelayStore) -> Result<()> {
    let path = data_dir.join(RELAYS_FILE);
    let data = serde_json::to_string_pretty(store)?;
    fs::write(&path, data).await.context("Writing relay store")
}

fn seed_defaults() -> RelayStore {
    let now = chrono::Utc::now().to_rfc3339();
    RelayStore {
        relays: DEFAULT_RELAYS
            .iter()
            .map(|url| RelayConfig {
                url: url.to_string(),
                enabled: true,
                added_at: now.clone(),
            })
            .collect(),
    }
}

/// List all relays with connection status.
pub async fn list_relays(data_dir: &Path) -> Result<Vec<RelayStatus>> {
    let store = load_relays(data_dir).await?;
    let statuses: Vec<RelayStatus> = store
        .relays
        .into_iter()
        .map(|r| {
            // Connection check: try a quick TCP probe to the relay
            // For now, report enabled relays as connected (actual connectivity
            // is tested via the Nostr SDK when publishing/subscribing)
            RelayStatus {
                url: r.url,
                connected: r.enabled,
                enabled: r.enabled,
                added_at: r.added_at,
            }
        })
        .collect();
    Ok(statuses)
}

/// Add a new relay.
pub async fn add_relay(data_dir: &Path, url: &str) -> Result<RelayConfig> {
    let mut store = load_relays(data_dir).await?;

    let normalized = normalize_relay_url(url)?;

    if store.relays.iter().any(|r| r.url == normalized) {
        return Err(anyhow::anyhow!("Relay already exists: {}", normalized));
    }

    let config = RelayConfig {
        url: normalized,
        enabled: true,
        added_at: chrono::Utc::now().to_rfc3339(),
    };

    debug!(url = %config.url, "Added relay");
    store.relays.push(config.clone());
    save_relays(data_dir, &store).await?;
    Ok(config)
}

/// Remove a relay.
pub async fn remove_relay(data_dir: &Path, url: &str) -> Result<()> {
    let mut store = load_relays(data_dir).await?;
    let original_len = store.relays.len();
    store.relays.retain(|r| r.url != url);
    if store.relays.len() == original_len {
        return Err(anyhow::anyhow!("Relay not found: {}", url));
    }
    save_relays(data_dir, &store).await
}

/// Toggle relay enabled/disabled.
pub async fn toggle_relay(data_dir: &Path, url: &str, enabled: bool) -> Result<()> {
    let mut store = load_relays(data_dir).await?;
    let relay = store
        .relays
        .iter_mut()
        .find(|r| r.url == url)
        .ok_or_else(|| anyhow::anyhow!("Relay not found: {}", url))?;
    relay.enabled = enabled;
    save_relays(data_dir, &store).await
}

/// Get aggregate stats.
pub async fn get_stats(data_dir: &Path) -> Result<RelayStats> {
    let store = load_relays(data_dir).await?;
    let enabled_count = store.relays.iter().filter(|r| r.enabled).count();
    Ok(RelayStats {
        total_relays: store.relays.len(),
        connected_count: enabled_count,
        enabled_count,
    })
}

/// Normalize a relay URL (ensure wss:// prefix).
fn normalize_relay_url(url: &str) -> Result<String> {
    let trimmed = url.trim();
    if trimmed.is_empty() {
        return Err(anyhow::anyhow!("Relay URL cannot be empty"));
    }
    if trimmed.starts_with("wss://") || trimmed.starts_with("ws://") {
        Ok(trimmed.to_string())
    } else {
        Ok(format!("wss://{}", trimmed))
    }
}