// src/corporate/update_parallel.rs
// PARALLELIZED VERSION of build_companies_jsonl_streaming
// 
// Key improvements:
// - Processes multiple companies concurrently using the ChromeDriverPool
// - Maintains data safety with serialized log writes via channel
// - Respects pool size limits via semaphore
// - All fsync and checkpoint logic preserved

use super::{types::*, yahoo::*};
use crate::util::directories::DataPaths;
use crate::util::logger;
use crate::scraper::webdriver::ChromeDriverPool;

use rand::Rng;
use tokio::sync::mpsc;
use tokio::io::AsyncWriteExt;
use tokio::fs::OpenOptions;
use tokio::time::sleep;
use std::collections::HashMap;
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
use std::time::Duration;
use futures::stream::{FuturesUnordered, StreamExt};
use anyhow::{anyhow, Context, Result};


/// Represents a write command to be serialized through the log writer
enum LogCommand {
    Write(CompanyCrossPlatformInfo),
    Checkpoint,
    Shutdown,
}

/// Result from processing a single company
struct CompanyProcessResult {
    company: CompanyCrossPlatformInfo,
    is_update: bool,
}

/// Abort-safe incremental JSONL persistence with atomic checkpoints (PARALLELIZED)
/// 
/// Implements the data_updating_rule.md specification with concurrent processing:
/// - Append-only JSONL log for all updates
/// - Batched fsync for performance (configurable batch size)
/// - Time-based fsync for safety (max 10 seconds without fsync)
/// - Atomic checkpoints via temp file + rename
/// - Crash recovery by loading checkpoint + replaying log
/// - Partial lines automatically ignored by .lines() iterator
/// - PARALLEL processing of companies using ChromeDriverPool
/// - Serialized log writes for data safety
/// 
/// # Parallelization Strategy
/// 
/// - Multiple companies processed concurrently (limited by pool size)
/// - Each company's Yahoo lookups happen in parallel
/// - Log writes are serialized through a channel
/// - Pool's semaphore naturally limits concurrency
/// - All fsync and checkpoint logic preserved
pub async fn build_companies_jsonl_streaming_parallel(
    paths: &DataPaths, 
    pool: &Arc<ChromeDriverPool>,
    shutdown_flag: &Arc<AtomicBool>,
) -> anyhow::Result<usize> {
    // Configuration constants
    const CHECKPOINT_INTERVAL: usize = 50;
    const FSYNC_BATCH_SIZE: usize = 10;
    const FSYNC_INTERVAL_SECS: u64 = 10;
    const CONCURRENCY_LIMIT: usize = 100; // Max companies processing at once
    
    let path = DataPaths::new(".")?;
    let corporate_path = path.data_dir().join("corporate").join("by_name");
    let securities_path = corporate_path.join("common_stocks.json");
    
    if !securities_path.exists() {
        logger::log_warn("No common_stocks.json found").await;
        return Ok(0);
    }
    
    let content = tokio::fs::read_to_string(securities_path).await?;
    let securities: HashMap<String, CompanyInfo> = serde_json::from_str(&content)?;
    
    let companies_path = paths.data_dir().join("companies.jsonl");
    let log_path = paths.data_dir().join("companies_updates.log");
    
    if let Some(parent) = companies_path.parent() {
        tokio::fs::create_dir_all(parent).await?;
    }
    
    // === RECOVERY PHASE: Load checkpoint + replay log ===
    let mut existing_companies: HashMap<String, CompanyCrossPlatformInfo> = HashMap::new();
    let mut processed_names: std::collections::HashSet<String> = std::collections::HashSet::new();
    
    if companies_path.exists() {
        logger::log_info("Loading checkpoint from companies.jsonl...").await;
        let existing_content = tokio::fs::read_to_string(&companies_path).await?;
        
        for line in existing_content.lines() {
            if line.trim().is_empty() {
                continue;
            }
            
            match serde_json::from_str::<CompanyCrossPlatformInfo>(line) {
                Ok(company) => {
                    processed_names.insert(company.name.clone());
                    existing_companies.insert(company.name.clone(), company);
                }
                Err(e) => {
                    logger::log_warn(&format!("Skipping invalid checkpoint line: {}", e)).await;
                }
            }
        }
        logger::log_info(&format!("Loaded checkpoint with {} companies", existing_companies.len())).await;
    }
    
    if log_path.exists() {
        logger::log_info("Replaying update log...").await;
        let log_content = tokio::fs::read_to_string(&log_path).await?;
        let mut replayed = 0;
        
        for line in log_content.lines() {
            if line.trim().is_empty() {
                continue;
            }
            
            match serde_json::from_str::<CompanyCrossPlatformInfo>(line) {
                Ok(company) => {
                    processed_names.insert(company.name.clone());
                    existing_companies.insert(company.name.clone(), company);
                    replayed += 1;
                }
                Err(e) => {
                    logger::log_warn(&format!("Skipping invalid log line: {}", e)).await;
                }
            }
        }
        if replayed > 0 {
            logger::log_info(&format!("Replayed {} updates from log", replayed)).await;
        }
    }
    
    // === SETUP LOG WRITER TASK ===
    // This task serializes all log writes to maintain data safety
    let (write_tx, mut write_rx) = mpsc::channel::<LogCommand>(1000);
    
    let log_file_init = OpenOptions::new()
        .create(true)
        .append(true)
        .open(&log_path)
        .await?;
    
    let companies_path_clone = companies_path.clone();
    let log_path_clone = log_path.clone();
    let existing_companies_writer = Arc::new(tokio::sync::Mutex::new(existing_companies.clone()));
    
    let writer_task = tokio::spawn(async move {
        let mut log_file = log_file_init; // Move into the task
        let mut writes_since_fsync = 0;
        let mut last_fsync = std::time::Instant::now();
        let mut updates_since_checkpoint = 0;
        let mut count = 0;
        let mut new_count = 0;
        let mut updated_count = 0;
        
        while let Some(cmd) = write_rx.recv().await {
            match cmd {
                LogCommand::Write(company) => {
                    // Write to log
                    let line = serde_json::to_string(&company).unwrap();
                    if let Err(e) = log_file.write_all(line.as_bytes()).await {
                        logger::log_error(&format!("Failed to write to log: {}", e)).await;
                        break;
                    }
                    if let Err(e) = log_file.write_all(b"\n").await {
                        logger::log_error(&format!("Failed to write newline: {}", e)).await;
                        break;
                    }
                    
                    writes_since_fsync += 1;
                    updates_since_checkpoint += 1;
                    count += 1;
                    
                    // Update in-memory state
                    let mut existing_companies = existing_companies_writer.lock().await;
                    let is_update = existing_companies.contains_key(&company.name);
                    existing_companies.insert(company.name.clone(), company);
                    drop(existing_companies);
                    
                    if is_update {
                        updated_count += 1;
                    } else {
                        new_count += 1;
                    }
                    
                    // Batched + time-based fsync
                    let should_fsync = writes_since_fsync >= FSYNC_BATCH_SIZE 
                        || last_fsync.elapsed().as_secs() >= FSYNC_INTERVAL_SECS;
                    
                    if should_fsync {
                        if let Err(e) = log_file.flush().await {
                            logger::log_error(&format!("Failed to flush: {}", e)).await;
                            break;
                        }
                        if let Err(e) = log_file.sync_data().await {
                            logger::log_error(&format!("Failed to fsync: {}", e)).await;
                            break;
                        }
                        writes_since_fsync = 0;
                        last_fsync = std::time::Instant::now();
                    }
                    
                    // Periodic checkpoint
                    if updates_since_checkpoint >= CHECKPOINT_INTERVAL {
                        // Fsync pending writes before checkpoint
                        if writes_since_fsync > 0 {
                            let _ = log_file.flush().await;
                            let _ = log_file.sync_data().await;
                            writes_since_fsync = 0;
                            last_fsync = std::time::Instant::now();
                        }
                        
                        logger::log_info(&format!("Creating checkpoint at {} companies...", count)).await;
                        
                        let checkpoint_tmp = companies_path_clone.with_extension("jsonl.tmp");
                        let mut checkpoint_file = match tokio::fs::File::create(&checkpoint_tmp).await {
                            Ok(f) => f,
                            Err(e) => {
                                logger::log_error(&format!("Failed to create checkpoint: {}", e)).await;
                                break;
                            }
                        };
                        
                        let existing_companies = existing_companies_writer.lock().await;
                        for company in existing_companies.values() {
                            let line = serde_json::to_string(company).unwrap();
                            let _ = checkpoint_file.write_all(line.as_bytes()).await;
                            let _ = checkpoint_file.write_all(b"\n").await;
                        }
                        drop(existing_companies);
                        
                        let _ = checkpoint_file.flush().await;
                        let _ = checkpoint_file.sync_all().await;
                        drop(checkpoint_file);
                        
                        let _ = tokio::fs::rename(&checkpoint_tmp, &companies_path_clone).await;
                        
                        // Clear log and reopen
                        drop(log_file);
                        let _ = tokio::fs::remove_file(&log_path_clone).await;
                        
                        // Reopen log file
                        match OpenOptions::new()
                            .create(true)
                            .append(true)
                            .open(&log_path_clone)
                            .await {
                                Ok(new_file) => {
                                    log_file = new_file;
                                    updates_since_checkpoint = 0;
                                    logger::log_info("✓ Checkpoint created and log cleared").await;
                                }
                                Err(e) => {
                                    logger::log_error(&format!("Failed to reopen log: {}", e)).await;
                                    break;
                                }
                            }
                    }
                    
                    if count % 10 == 0 {
                        logger::log_info(&format!("Progress: {} companies ({} new, {} updated)", count, new_count, updated_count)).await;
                    }
                },
                LogCommand::Checkpoint => {
                    // Force checkpoint - this is the final checkpoint before shutdown
                    if writes_since_fsync > 0 {
                        let _ = log_file.flush().await;
                        let _ = log_file.sync_data().await;
                    }
                    
                    logger::log_info("Creating final checkpoint...").await;
                    let checkpoint_tmp = companies_path_clone.with_extension("jsonl.tmp");
                    if let Ok(mut checkpoint_file) = tokio::fs::File::create(&checkpoint_tmp).await {
                        let existing_companies = existing_companies_writer.lock().await;
                        for company in existing_companies.values() {
                            let line = serde_json::to_string(company).unwrap();
                            let _ = checkpoint_file.write_all(line.as_bytes()).await;
                            let _ = checkpoint_file.write_all(b"\n").await;
                        }
                        drop(existing_companies);
                        
                        let _ = checkpoint_file.flush().await;
                        let _ = checkpoint_file.sync_all().await;
                        drop(checkpoint_file);
                        let _ = tokio::fs::rename(&checkpoint_tmp, &companies_path_clone).await;
                        
                        // Clean up log file after final checkpoint
                        drop(log_file);
                        let _ = tokio::fs::remove_file(&log_path_clone).await;
                        
                        logger::log_info("✓ Final checkpoint created").await;
                    }
                    // After final checkpoint, exit the loop
                    break;
                },
                LogCommand::Shutdown => {
                    // Fsync any pending writes before exit
                    if writes_since_fsync > 0 {
                        logger::log_info(&format!("Fsyncing {} pending writes...", writes_since_fsync)).await;
                        let _ = log_file.flush().await;
                        let _ = log_file.sync_data().await;
                    }
                    break;
                }
            }
        }
        
        (count, new_count, updated_count)
    });
    
    // === PARALLEL COMPANY PROCESSING ===
    logger::log_info(&format!("Processing companies in parallel (max {} concurrent, pool size: {})", 
        CONCURRENCY_LIMIT, pool.get_number_of_instances())).await;
    
    let pool = pool.clone();
    let shutdown_flag = shutdown_flag.clone();
    
    let mut processing_tasks = FuturesUnordered::new();
    let mut pending_companies = Vec::new();
    
    // Collect companies to process
    for (name, company_info) in securities.iter() {
        if processed_names.contains(name) {
            continue;
        }
        pending_companies.push((name.clone(), company_info.clone()));
    }
    
    logger::log_info(&format!("Found {} companies to process", pending_companies.len())).await;
    
    // Process companies in chunks to limit memory usage
    let chunk_size = CONCURRENCY_LIMIT;
    let mut processed = 0;
    
    for chunk in pending_companies.chunks(chunk_size) {
        if shutdown_flag.load(Ordering::SeqCst) {
            break;
        }
        
        // Launch tasks for this chunk
        for (name, company_info) in chunk {
            let name = name.clone();
            let company_info = company_info.clone();
            let pool = pool.clone();
            let shutdown_flag = shutdown_flag.clone();
            let existing_entry = existing_companies.get(&name).cloned();
            
            let task = tokio::spawn(async move {
                process_single_company(
                    name,
                    company_info,
                    existing_entry,
                    &pool,
                    &shutdown_flag
                ).await
            });
            
            processing_tasks.push(task);
        }
        
        // Wait for chunk to complete
        while let Some(result) = processing_tasks.next().await {
            match result {
                Ok(Ok(Some(company_result))) => {
                    // Send to writer
                    if write_tx.send(LogCommand::Write(company_result.company)).await.is_err() {
                        logger::log_error("Writer task died, stopping processing").await;
                        break;
                    }
                    processed += 1;
                }
                Ok(Ok(None)) => {
                    // Company had no ISINs or was skipped
                    processed += 1;
                }
                Ok(Err(e)) => {
                    logger::log_warn(&format!("Company processing error: {}", e)).await;
                    processed += 1;
                }
                Err(e) => {
                    logger::log_error(&format!("Task panic: {}", e)).await;
                    processed += 1;
                }
            }
            
            if shutdown_flag.load(Ordering::SeqCst) {
                break;
            }
        }
        
        if shutdown_flag.load(Ordering::SeqCst) {
            break;
        }
    }
    
    // Signal writer to finish
    let _ = write_tx.send(LogCommand::Shutdown).await;
    drop(write_tx);
    
    // Wait for writer to finish
    let (final_count, final_new, final_updated) = writer_task.await
        .unwrap_or((0, 0, 0));
    
    logger::log_info(&format!(
        "Completed: {} total companies ({} new, {} updated)", 
        final_count, final_new, final_updated
    )).await;
    
    Ok(final_count)
}

async fn scrape_with_retry(
    pool: &Arc<ChromeDriverPool>,
    isin: &str,
    max_retries: u32,
) -> Result<Option<YahooCompanyDetails>> {
    let mut retries = 0;
    
    loop {
        match scrape_company_details_by_isin(pool, isin).await {
            Ok(result) => return Ok(result),
            Err(e) => {
                if retries >= max_retries {
                    return Err(e);
                }
                
                let backoff_ms = 1000 * 2u64.pow(retries);  // 1s, 2s, 4s, 8s
                let jitter_ms = rand::rng().random_range(0..500);  // +0-500ms Jitter
                let total_delay = backoff_ms + jitter_ms;
                
                logger::log_warn(&format!(
                    "Retry {}/{} for ISIN {} after {}ms: {}",
                    retries + 1, max_retries, isin, total_delay, e
                )).await;
                
                sleep(Duration::from_millis(total_delay)).await;
                retries += 1;
            }
        }
    }
}

/// Process a single company: fetch Yahoo data for its ISINs
async fn process_single_company(
    name: String,
    company_info: CompanyInfo,
    existing_entry: Option<CompanyCrossPlatformInfo>,
    pool: &Arc<ChromeDriverPool>,
    shutdown_flag: &Arc<AtomicBool>,
) -> anyhow::Result<Option<CompanyProcessResult>> {
    let is_update = existing_entry.is_some();
    
    let mut isin_tickers_map: HashMap<String, Vec<String>> = 
        existing_entry
            .as_ref()
            .map(|e| e.isin_tickers_map.clone())
            .unwrap_or_default();
    
    let mut sector = existing_entry.as_ref().and_then(|e| e.sector.clone());
    let mut exchange = existing_entry.as_ref().and_then(|e| e.exchange.clone());
    
    // Collect unique ISIN-ticker pairs
    let mut unique_isin_ticker_pairs: HashMap<String, Vec<String>> = HashMap::new();
    
    for figi_infos in company_info.securities.values() {
        for figi_info in figi_infos {
            if !figi_info.isin.is_empty() {
                let tickers = unique_isin_ticker_pairs
                    .entry(figi_info.isin.clone())
                    .or_insert_with(Vec::new);
                
                if !figi_info.ticker.is_empty() && !tickers.contains(&figi_info.ticker) {
                    tickers.push(figi_info.ticker.clone());
                }
            }
        }
    }
    
    // Process each ISIN (these Yahoo lookups will happen in parallel across companies)
    for (isin, figi_tickers) in unique_isin_ticker_pairs {
        if shutdown_flag.load(Ordering::SeqCst) {
            break;
        }

        let tickers = isin_tickers_map
            .entry(isin.clone())
            .or_insert_with(Vec::new);
        
        for figi_ticker in figi_tickers {
            if !tickers.contains(&figi_ticker) {
                tickers.push(figi_ticker);
            }
        }
        
        let has_yahoo_ticker = tickers.iter().any(|t| t.starts_with("YAHOO:"));
        
        if !has_yahoo_ticker && !shutdown_flag.load(Ordering::SeqCst) {
            logger::log_info(&format!("Fetching Yahoo details for {} (ISIN: {})", name, isin)).await;
            match scrape_with_retry(pool, &isin, 3).await {
                Ok(Some(details)) => {
                    logger::log_info(&format!("✓ Found Yahoo ticker {} for ISIN {}", details.ticker, isin)).await;
                    
                    tickers.push(format!("YAHOO:{}", details.ticker));
                    
                    if sector.is_none() && details.sector.is_some() {
                        sector = details.sector.clone();
                        logger::log_info(&format!("  Sector: {}", details.sector.as_ref().unwrap())).await;
                    }
                    
                    if exchange.is_none() && details.exchange.is_some() {
                        exchange = details.exchange.clone();
                        logger::log_info(&format!("  Exchange: {}", details.exchange.as_ref().unwrap())).await;
                    }
                },
                Ok(None) => {
                    logger::log_warn(&format!("◯ No search results for ISIN {}", isin)).await;
                    tickers.push("YAHOO:NO_RESULTS".to_string());
                },
                Err(e) => {
                    if shutdown_flag.load(Ordering::SeqCst) {
                        break;
                    }
                    logger::log_warn(&format!("✗ Yahoo lookup error for ISIN {}: {}", isin, e)).await;
                }
            }
        }
    }
    
    if shutdown_flag.load(Ordering::SeqCst) {
        return Ok(None);
    }

    if !isin_tickers_map.is_empty() {
        let company_entry = CompanyCrossPlatformInfo {
            name: name.clone(),
            isin_tickers_map,
            sector,
            exchange,
        };
        
        Ok(Some(CompanyProcessResult {
            company: company_entry,
            is_update,
        }))
    } else {
        Ok(None)
    }
}