use anyhow::Result;
use std::path::Path;
use tokio::time;
use tracing::{info, warn};

pub struct WatcherConfig {
    pub directories: Vec<String>,
    pub poll_interval_ms: u64,
}

impl Default for WatcherConfig {
    fn default() -> Self {
        let default_dir = std::env::var("MOMENTRY_SFTP_ROOT")
            .unwrap_or_else(|_| "/Users/accusys/momentry/var/sftpgo/data/demo/".to_string());
        Self {
            directories: vec![default_dir],
            poll_interval_ms: 60000,
        }
    }
}

/// Starts the file watcher in the background.
/// Detects new files and logs them. Does NOT auto-register or auto-pre-process.
pub async fn run_watcher() -> Result<()> {
    let config = WatcherConfig::default();
    let dirs = config.directories.clone();

    if dirs.is_empty() {
        warn!("No directories configured for watching.");
        return Err(anyhow::anyhow!("No watch directories"));
    }

    info!("Starting File Watcher (detection only, no auto-modification)...");
    info!("Watch directories: {:?}", dirs);

    tokio::spawn(async move {
        let mut interval = time::interval(std::time::Duration::from_millis(config.poll_interval_ms));
        // Track known files across cycles
        let mut known = std::collections::HashSet::new();
        loop {
            interval.tick().await;
            report_new_files(&dirs, &mut known).await;
        }
    });

    Ok(())
}

async fn report_new_files(directories: &[String], known: &mut std::collections::HashSet<String>) {
    for dir in directories {
        let dir_path = Path::new(dir);
        if !dir_path.is_dir() {
            continue;
        }
        let entries = match std::fs::read_dir(dir_path) {
            Ok(e) => e,
            _ => continue,
        };

        let mut current_files = std::collections::HashSet::new();
        for entry in entries.flatten() {
            let file_path = entry.path();
            if !file_path.is_file() {
                continue;
            }
            let fname = match file_path.file_name().and_then(|n| n.to_str()) {
                Some(n) if !n.starts_with('.') && !n.ends_with(".pre.json") => n.to_string(),
                _ => continue,
            };
            current_files.insert(fname.clone());
            if !known.contains(&fname) {
                info!("[WATCHER] New file detected: {} in {}", fname, dir);
                known.insert(fname);
            }
        }
        // Remove files that no longer exist (deleted between cycles)
        known.retain(|k| current_files.contains(k));
    }
}

/// Pre-process a single file: compute SHA256 + probe + UUID → .pre.json
/// This is called explicitly from register API, NOT from the watcher.
pub async fn pre_process_file(file_path: &str) -> Option<String> {
    let path = std::path::Path::new(file_path);
    if !path.is_file() {
        return None;
    }
    let canonical = path.canonicalize().ok()?;
    let canonical_str = canonical.to_string_lossy().to_string();
    let filename = path.file_name()?.to_string_lossy().to_string();

    let output_dir = std::env::var("MOMENTRY_OUTPUT_DIR")
        .unwrap_or_else(|_| "/Users/accusys/momentry/output_dev".to_string());

    let birthday = std::fs::metadata(&path).ok()
        .and_then(|m| m.created().ok())
        .map(|t| {
            let secs = t.duration_since(std::time::UNIX_EPOCH).unwrap_or_default().as_secs();
            chrono::DateTime::from_timestamp(secs as i64, 0)
                .map(|dt| dt.to_rfc3339())
                .unwrap_or_else(|| chrono::Utc::now().to_rfc3339())
        })
        .unwrap_or_else(|| chrono::Utc::now().to_rfc3339());

    let mac = crate::core::storage::uuid::get_mac_address();
    let file_uuid = crate::core::storage::uuid::compute_birth_uuid(
        &mac, &birthday, &canonical_str, &filename,
    );

    let pre_path = std::path::PathBuf::from(&output_dir).join(format!("{}.pre.json", file_uuid));
    if pre_path.exists() {
        info!("[PRE-PROCESS] Already pre-processed: {}", filename);
        return Some(file_uuid);
    }

    info!("[PRE-PROCESS] Pre-processing: {} → {}", filename, file_uuid);

    let content_hash = crate::core::storage::content_hash::compute_sha256(&path).unwrap_or_default();

    let probe_json: serde_json::Value = if let Ok(result) = crate::core::probe::probe_video(&canonical_str) {
        serde_json::to_value(&result).unwrap_or_default()
    } else {
        let size = std::fs::metadata(&path).ok().map(|m| m.len()).unwrap_or(0);
        serde_json::json!({
            "format": {"filename": canonical_str, "size": size.to_string(), "format_name": "unknown"},
            "streams": []
        })
    };

    let file_type = if probe_json.get("streams").and_then(|s| s.as_array())
        .map_or(false, |streams| streams.iter().any(|st| st.get("codec_type").and_then(|c| c.as_str()) == Some("video")))
    { "video" } else { "unknown" };

    let pre_data = serde_json::json!({
        "file_name": filename,
        "file_path": canonical_str,
        "content_hash": content_hash,
        "probe_json": probe_json,
        "birthday": birthday,
        "file_uuid": file_uuid,
        "file_size": std::fs::metadata(&path).ok().map(|m| m.len()).unwrap_or(0),
        "file_type": file_type,
        "pre_processed_at": chrono::Utc::now().to_rfc3339(),
    });

    if let Ok(content) = serde_json::to_string_pretty(&pre_data) {
        if std::fs::write(&pre_path, content).is_ok() {
            info!("[PRE-PROCESS] {} → {}.pre.json", filename, file_uuid);
        }
    }
    Some(file_uuid)
}