use crate::client::{ItemInfo, KeepClient};
use crate::compression_engine::CompressionType;
use crate::config::Settings;
use crate::meta_plugin::SaveMetaFn;
use crate::modes::common::settings_compression_type;
use crate::services::meta_service::MetaService;
use anyhow::Result;
use clap::Command;
use is_terminal::IsTerminal;
use log::debug;
use std::collections::HashMap;
use std::io::{Read, Write};
use std::sync::{Arc, Mutex};

/// Streaming save mode for client.
///
/// Uses three threads for true streaming with constant memory:
/// - Reader thread: reads stdin, tees to stdout, runs meta plugins,
///   compresses data, writes to OS pipe
/// - Pipe: zero-copy transfer of compressed bytes between threads
/// - Streamer thread: reads from pipe, streams to server via chunked HTTP
///
/// Meta plugins run on the client side during streaming. Collected metadata
/// is sent to the server via a separate POST after streaming completes.
///
/// Memory usage is O(PIPESIZE) regardless of data size.
pub fn mode(
    client: &KeepClient,
    cmd: &mut Command,
    settings: &Settings,
    tags: &mut Vec<String>,
    metadata: HashMap<String, String>,
) -> Result<(), anyhow::Error> {
    debug!("CLIENT_SAVE: Saving item via remote server (streaming)");

    crate::modes::common::ensure_default_tag(tags);

    // Determine compression type from settings
    let compression_type = settings_compression_type(cmd, settings);
    let server_compress = matches!(compression_type, CompressionType::None);

    // Shared metadata collection: plugins write here via save_meta closure
    let collected_meta: Arc<Mutex<HashMap<String, String>>> = Arc::new(Mutex::new(HashMap::new()));
    let meta_collector = collected_meta.clone();
    let save_meta: SaveMetaFn = Arc::new(Mutex::new(move |name: &str, value: &str| {
        if let Ok(mut map) = meta_collector.lock() {
            map.insert(name.to_string(), value.to_string());
        }
    }));

    // Create MetaService and get plugins (must happen before spawning reader thread)
    let meta_service = MetaService::new(save_meta);
    let mut plugins = meta_service.get_plugins(cmd, settings);

    // Create OS pipe for streaming compressed bytes between threads
    let (pipe_reader, pipe_writer) = os_pipe::pipe()?;

    // Reader thread: stdin → tee(stdout) → meta plugins → compress → pipe
    let compression_type_clone = compression_type.clone();
    let reader_handle = std::thread::spawn(move || -> Result<u64> {
        let stdin = std::io::stdin();
        let stdout = std::io::stdout();
        let mut stdin_lock = stdin.lock();
        let mut stdout_lock = stdout.lock();

        let mut total_bytes = 0u64;
        let mut buffer = [0u8; 8192];

        // Initialize meta plugins
        meta_service.initialize_plugins(&mut plugins);

        // Wrap pipe writer with appropriate compression
        let mut compressor: Box<dyn Write> = match compression_type_clone {
            CompressionType::GZip => {
                use flate2::Compression;
                use flate2::write::GzEncoder;
                Box::new(GzEncoder::new(pipe_writer, Compression::default()))
            }
            CompressionType::LZ4 => Box::new(lz4_flex::frame::FrameEncoder::new(pipe_writer)),
            _ => Box::new(pipe_writer),
        };

        loop {
            let n = stdin_lock.read(&mut buffer)?;
            if n == 0 {
                break;
            }

            // Tee to stdout
            stdout_lock.write_all(&buffer[..n])?;

            // Feed chunk to meta plugins
            meta_service.process_chunk(&mut plugins, &buffer[..n]);

            total_bytes += n as u64;

            // Compress and write to pipe
            compressor.write_all(&buffer[..n])?;
        }

        // Finalize meta plugins (digest, text, tokens produce final output here)
        meta_service.finalize_plugins(&mut plugins);

        // Explicitly flush and finalize compression before dropping.
        compressor.flush()?;
        drop(compressor);

        Ok(total_bytes)
    });

    // Streamer thread: reads compressed bytes from pipe → POST to server
    let client_url = client.base_url().to_string();
    let client_username = client.username().cloned();
    let client_password = client.password().cloned();
    let client_jwt = client.jwt().cloned();
    let tags_clone = tags.clone();

    let streamer_handle = std::thread::spawn(move || -> Result<ItemInfo> {
        let streaming_client =
            KeepClient::new(&client_url, client_username, client_password, client_jwt)?;
        let params = [
            ("compress".to_string(), server_compress.to_string()),
            ("meta".to_string(), "false".to_string()),
            ("tags".to_string(), tags_clone.join(",")),
        ];
        let param_refs: Vec<(&str, &str)> = params
            .iter()
            .map(|(k, v)| (k.as_str(), v.as_str()))
            .collect();

        let mut reader: Box<dyn Read> = Box::new(pipe_reader);
        let item_info = streaming_client.post_stream("/api/item/", &mut reader, &param_refs)?;
        Ok(item_info)
    });

    // Wait for streaming to complete, capture item info
    let item_info = streamer_handle
        .join()
        .map_err(|e| anyhow::anyhow!("Streamer thread panicked: {:?}", e))??;

    // Wait for reader thread (should complete quickly after pipe is drained)
    let uncompressed_size = reader_handle
        .join()
        .map_err(|e| anyhow::anyhow!("Reader thread panicked: {:?}", e))??;

    // Merge plugin-collected metadata with CLI metadata
    let mut local_metadata = metadata;

    // Add plugin-collected metadata (digest, hostname, text stats, etc.)
    if let Ok(plugin_meta) = collected_meta.lock() {
        for (k, v) in plugin_meta.iter() {
            local_metadata.entry(k.clone()).or_insert_with(|| v.clone());
        }
    }

    // Add uncompressed_size (always tracked by client)
    local_metadata.insert(
        "uncompressed_size".to_string(),
        uncompressed_size.to_string(),
    );

    // Record client compression type so the client can decompress on retrieval.
    if !matches!(compression_type, CompressionType::None) {
        local_metadata.insert(
            "_client_compression".to_string(),
            compression_type.to_string(),
        );
    }

    // Send metadata to server
    if !local_metadata.is_empty() {
        client.post_metadata(item_info.id, &local_metadata)?;
    }

    // Print status to stderr
    if !settings.quiet {
        if std::io::stderr().is_terminal() {
            eprintln!("KEEP: New item (streaming)  tags: {}", tags.join(" "));
        } else {
            eprintln!("KEEP: New item (streaming)  tags: {tags:?}");
        }
    }

    debug!("CLIENT_SAVE: Streaming complete, {uncompressed_size} bytes uncompressed");

    Ok(())
}