// Båndbredde-logging via Caddy-logg-parsing.
//
// Nattlig batch-jobb som leser Caddy JSON-access-logger og
// aggregerer bytes servert til resource_usage_log.
//
// Caddy JSON-format (relevante felter):
//   { "request": { "uri": "/media/...", "headers": { "User-Agent": [...] } },
//     "status": 200, "size": 84000000, "ts": 1710000000.0 }
//
// Ref: docs/features/ressursforbruk.md

use serde::Deserialize;
use sqlx::PgPool;
use uuid::Uuid;

/// Caddy JSON-loggformat (kun feltene vi trenger).
#[derive(Deserialize)]
struct CaddyLogEntry {
    request: CaddyRequest,
    #[serde(default)]
    status: u16,
    #[serde(default)]
    size: u64,
    #[serde(default)]
    #[allow(dead_code)]
    ts: f64,
}

#[derive(Deserialize)]
struct CaddyRequest {
    uri: String,
    #[serde(default)]
    headers: std::collections::HashMap<String, Vec<String>>,
}

/// Aggregert båndbredde per path.
struct BandwidthEntry {
    path: String,
    size_bytes: u64,
    client: String,
}

/// Parser en Caddy JSON-loggfil og returnerer båndbredde-entries
/// for media/CAS/pub-forespørsler med status 200-299.
fn parse_caddy_log(content: &str) -> Vec<BandwidthEntry> {
    let mut entries = Vec::new();

    for line in content.lines() {
        let line = line.trim();
        if line.is_empty() {
            continue;
        }

        let entry: CaddyLogEntry = match serde_json::from_str(line) {
            Ok(e) => e,
            Err(_) => continue,
        };

        // Kun vellykkede forespørsler med innhold
        if entry.status < 200 || entry.status >= 300 || entry.size == 0 {
            continue;
        }

        // Kun media-, CAS- og publiserings-trafikk
        let uri = &entry.request.uri;
        if !uri.starts_with("/media/")
            && !uri.starts_with("/cas/")
            && !uri.starts_with("/pub/")
        {
            continue;
        }

        let client = entry
            .request
            .headers
            .get("User-Agent")
            .or_else(|| entry.request.headers.get("user-agent"))
            .and_then(|vals| vals.first())
            .map(|ua| parse_client_name(ua))
            .unwrap_or_else(|| "unknown".to_string());

        entries.push(BandwidthEntry {
            path: uri.clone(),
            size_bytes: entry.size,
            client,
        });
    }

    entries
}

/// Ekstraher klientnavn fra User-Agent-streng.
fn parse_client_name(ua: &str) -> String {
    let ua_lower = ua.to_lowercase();
    if ua_lower.contains("apple podcasts") || ua_lower.contains("applepodcasts") {
        "Apple Podcasts".to_string()
    } else if ua_lower.contains("spotify") {
        "Spotify".to_string()
    } else if ua_lower.contains("overcast") {
        "Overcast".to_string()
    } else if ua_lower.contains("pocket casts") || ua_lower.contains("pocketcasts") {
        "Pocket Casts".to_string()
    } else if ua_lower.contains("firefox") {
        "Firefox".to_string()
    } else if ua_lower.contains("chrome") {
        "Chrome".to_string()
    } else if ua_lower.contains("safari") {
        "Safari".to_string()
    } else if ua_lower.contains("bot") || ua_lower.contains("crawler") {
        "bot".to_string()
    } else {
        // Returner første token (typisk klientnavn)
        ua.split_whitespace()
            .next()
            .unwrap_or("unknown")
            .chars()
            .take(50)
            .collect()
    }
}

/// Kjør båndbredde-logg-parsing for en gitt loggfil.
/// Leser filen, parser entries, og skriver til resource_usage_log.
///
/// Bruker en "synops_bandwidth_system"-node som target_node_id
/// (systemet selv — ikke en spesifikk brukernode).
pub async fn parse_and_log_bandwidth(db: &PgPool, log_path: &str) -> Result<u64, String> {
    let content = tokio::fs::read_to_string(log_path)
        .await
        .map_err(|e| format!("Kunne ikke lese loggfil {log_path}: {e}"))?;

    let entries = parse_caddy_log(&content);
    if entries.is_empty() {
        tracing::info!(log_path = %log_path, "Ingen bandwidth-entries i loggfilen");
        return Ok(0);
    }

    // Finn en system-node å logge mot. Bruk Sidelinja-samlingsnoden
    // som fallback target for bandwidth-logging.
    let system_node_id: Uuid = sqlx::query_scalar::<_, Uuid>(
        "SELECT id FROM nodes WHERE node_kind = 'collection' ORDER BY created_at ASC LIMIT 1",
    )
    .fetch_optional(db)
    .await
    .map_err(|e| format!("PG-feil: {e}"))?
    .unwrap_or_else(Uuid::nil);

    let mut logged = 0u64;

    for entry in &entries {
        if let Err(e) = crate::resource_usage::log(
            db,
            system_node_id,
            None, // system-jobb, ingen bruker
            None,
            "bandwidth",
            serde_json::json!({
                "size_bytes": entry.size_bytes,
                "path": entry.path,
                "client": entry.client
            }),
        )
        .await
        {
            tracing::warn!(error = %e, path = %entry.path, "Kunne ikke logge bandwidth-entry");
        } else {
            logged += 1;
        }
    }

    tracing::info!(
        log_path = %log_path,
        entries = entries.len(),
        logged = logged,
        "Bandwidth-logging fullført"
    );

    Ok(logged)
}

/// Start periodisk båndbredde-parsing (nattlig batch-jobb, kjører kl 03:00).
pub fn start_bandwidth_parser(db: PgPool) {
    tokio::spawn(async move {
        tracing::info!("Bandwidth-parser startet (nattlig jobb kl 03:00)");

        loop {
            // Beregn tid til neste kjøring (kl 03:00)
            let now = chrono::Utc::now();
            let today_03 = now
                .date_naive()
                .and_hms_opt(3, 0, 0)
                .unwrap();
            let next_run = if now.naive_utc() > today_03 {
                // Allerede passert 03:00 i dag — kjør i morgen
                today_03 + chrono::Duration::days(1)
            } else {
                today_03
            };

            let sleep_duration = (next_run - now.naive_utc())
                .to_std()
                .unwrap_or(std::time::Duration::from_secs(3600));

            tracing::debug!(
                next_run = %next_run,
                sleep_secs = sleep_duration.as_secs(),
                "Bandwidth-parser sover til neste kjøring"
            );

            tokio::time::sleep(sleep_duration).await;

            // Kjør parsing for alle loggfiler
            let log_files = vec![
                "/var/log/caddy/access-sidelinja.log",
                "/var/log/caddy/access-synops.log",
            ];

            for path in &log_files {
                match parse_and_log_bandwidth(&db, path).await {
                    Ok(count) => {
                        if count > 0 {
                            tracing::info!(path = %path, entries = count, "Bandwidth-logging fullført");
                        }
                    }
                    Err(e) => {
                        tracing::warn!(path = %path, error = %e, "Bandwidth-parsing feilet");
                    }
                }
            }
        }
    });
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_caddy_log_basic() {
        let log = r#"{"request":{"uri":"/media/podcast/ep47.mp3","headers":{"User-Agent":["Apple Podcasts/1.0"]}},"status":200,"size":84000000,"ts":1710000000.0}
{"request":{"uri":"/api/health","headers":{}},"status":200,"size":42,"ts":1710000001.0}
{"request":{"uri":"/pub/sidelinja/article-1","headers":{"User-Agent":["Mozilla/5.0 Chrome/120"]}},"status":200,"size":15000,"ts":1710000002.0}
{"request":{"uri":"/media/podcast/ep47.mp3","headers":{}},"status":304,"size":0,"ts":1710000003.0}
"#;

        let entries = parse_caddy_log(log);
        assert_eq!(entries.len(), 2); // /api/health filtreres ut, 304 filtreres ut
        assert_eq!(entries[0].path, "/media/podcast/ep47.mp3");
        assert_eq!(entries[0].size_bytes, 84000000);
        assert_eq!(entries[0].client, "Apple Podcasts");
        assert_eq!(entries[1].path, "/pub/sidelinja/article-1");
        assert_eq!(entries[1].client, "Chrome");
    }

    #[test]
    fn test_parse_client_name() {
        assert_eq!(parse_client_name("ApplePodcasts/3.0"), "Apple Podcasts");
        assert_eq!(parse_client_name("Spotify/8.6.0"), "Spotify");
        assert_eq!(
            parse_client_name("Mozilla/5.0 (compatible; Googlebot/2.1)"),
            "bot"
        );
        assert_eq!(
            parse_client_name("Mozilla/5.0 Chrome/120.0"),
            "Chrome"
        );
    }

    #[test]
    fn test_parse_caddy_log_empty() {
        assert!(parse_caddy_log("").is_empty());
        assert!(parse_caddy_log("\n\n").is_empty());
    }
}