use anyhow::{Context, Result};
use rusqlite::Connection;
use sha2::{Digest, Sha256};
use std::collections::HashMap;
use std::fs;
use std::path::Path;
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Instant;

use crate::filetree::node::{Aliases, FileNode, NodeType};
use crate::filetree::FileTree;

pub struct ScanOptions {
    pub skip_hash: bool,
    pub threads: usize,
}

impl Default for ScanOptions {
    fn default() -> Self {
        ScanOptions {
            skip_hash: true,
            threads: 4,
        }
    }
}

pub fn scan_directory(user_id: &str, dir: &str, batch_size: usize, options: ScanOptions) -> Result<()> {
    let start = Instant::now();
    let dir_path = Path::new(dir);
    
    if !dir_path.exists() {
        anyhow::bail!("Directory not found: {}", dir);
    }
    
    println!("=== File Scan Performance Test ===");
    println!("User ID: {}", user_id);
    println!("Directory: {}", dir);
    println!("Batch size: {}", batch_size);
    println!("Skip hash: {}", options.skip_hash);
    if !options.skip_hash {
        println!("Hash threads: {}", options.threads);
    }
    println!();
    
    println!("[1/4] Scanning directory structure...");
    let scan_start = Instant::now();
    
    let mut folders: Vec<(String, String, Option<String>)> = Vec::new();
    let mut files: Vec<(String, String, u64, String)> = Vec::new();
    
    scan_recursive(dir_path, dir_path, &mut folders, &mut files)?;
    
    let scan_duration = scan_start.elapsed();
    println!("      Scanned {} folders, {} files in {:.2}s", 
        folders.len(), files.len(), scan_duration.as_secs_f64());
    
    println!();
    println!("[2/5] Generating node IDs...");
    let id_start = Instant::now();
    
    let mac = get_mac_address()?;
    
    let mut folder_nodes: Vec<FileNode> = Vec::new();
    let mut file_nodes: Vec<FileNode> = Vec::new();
    let mut file_info: Vec<(String, String)> = Vec::new();
    
    let mac_str = get_mac_address()?;
    
    let root_node_id = generate_uuid(&dir_path.to_string_lossy(), "Home", &mac_str, chrono::Utc::now().timestamp() as u64);
    
    folder_nodes.push(FileNode {
        node_id: root_node_id.clone(),
        label: "Home".to_string(),
        aliases: Aliases::empty(),
        file_uuid: None,
        sha256: None,
        parent_id: None,
        children: Vec::new(),
        node_type: NodeType::Folder,
        icon: Some("🏠".to_string()),
        color: None,
        bg_color: None,
        file_size: None,
        registered_at: None,
        created_at: chrono::Utc::now().timestamp().to_string(),
        updated_at: chrono::Utc::now().timestamp().to_string(),
        sort_order: 0,
    });
    
    let folder_id_map: HashMap<String, String> = {
        let mut map = HashMap::new();
        map.insert(dir_path.to_string_lossy().to_string(), root_node_id.clone());
        
        for (path_str, label, _parent_path) in &folders {
            let mtime = fs::metadata(path_str)
                .and_then(|m| m.modified())
                .unwrap_or(std::time::SystemTime::UNIX_EPOCH);
            let mtime_secs = mtime.duration_since(std::time::SystemTime::UNIX_EPOCH)
                .unwrap_or_default()
                .as_secs();
            
            let node_id = generate_uuid(path_str, label, &mac_str, mtime_secs);
            map.insert(path_str.clone(), node_id);
        }
        
        map
    };
    
    for (path_str, label, parent_path) in &folders {
        let node_id = folder_id_map.get(path_str).cloned().unwrap();
        
        let parent_node_id = if let Some(ref parent_p) = parent_path {
            folder_id_map.get(parent_p).cloned()
        } else {
            Some(root_node_id.clone())
        };
        
        folder_nodes.push(FileNode {
            node_id,
            label: label.clone(),
            aliases: Aliases::empty(),
            file_uuid: None,
            sha256: None,
            parent_id: parent_node_id,
            children: Vec::new(),
            node_type: NodeType::Folder,
            icon: Some("📁".to_string()),
            color: None,
            bg_color: None,
            file_size: None,
            registered_at: None,
            created_at: chrono::Utc::now().timestamp().to_string(),
            updated_at: chrono::Utc::now().timestamp().to_string(),
            sort_order: 0,
        });
    }
    
    for (path_str, filename, size, _ext) in &files {
        let mtime = fs::metadata(path_str)
            .and_then(|m| m.modified())
            .unwrap_or(std::time::SystemTime::UNIX_EPOCH);
        let mtime_secs = mtime.duration_since(std::time::SystemTime::UNIX_EPOCH)
            .unwrap_or_default()
            .as_secs();
        
        let node_id = generate_uuid(path_str, filename, &mac, mtime_secs);
        
        let file_dir = Path::new(path_str).parent().unwrap_or(dir_path);
        let parent_node_id = if file_dir == dir_path {
            Some(root_node_id.clone())
        } else {
            folder_id_map.get(file_dir.to_string_lossy().as_ref()).cloned()
        };
        
        let node_id_clone = node_id.clone();
        
        file_info.push((node_id_clone.clone(), path_str.clone()));
        
        file_nodes.push(FileNode {
            node_id: node_id_clone.clone(),
            label: filename.clone(),
            aliases: {
                let mut aliases = Aliases::empty();
                aliases.set("path", path_str);
                aliases
            },
            file_uuid: Some(node_id_clone.clone()),
            sha256: None,
            parent_id: parent_node_id,
            children: Vec::new(),
            node_type: NodeType::File,
            icon: get_file_icon(filename),
            color: None,
            bg_color: None,
            file_size: Some(*size as i64),
            registered_at: Some(chrono::Utc::now().timestamp().to_string()),
            created_at: chrono::Utc::now().timestamp().to_string(),
            updated_at: chrono::Utc::now().timestamp().to_string(),
            sort_order: 0,
        });
    }
    
    let id_duration = id_start.elapsed();
    println!("      Generated {} folder IDs, {} file IDs in {:.2}s", 
        folder_nodes.len(), file_nodes.len(), id_duration.as_secs_f64());
    
    println!();
    println!("[3/5] Opening database...");
    let db_start = Instant::now();
    
    let db_path = FileTree::user_db_path(user_id);
    if !Path::new(&db_path).exists() {
        FileTree::init_user_db(user_id)?;
    }
    
    let conn = FileTree::open_user_db(user_id)
        .with_context(|| format!("Failed to open database for user {}", user_id))?;
    
    let db_duration = db_start.elapsed();
    println!("      Database opened in {:.2}s", db_duration.as_secs_f64());
    
    println!();
    println!("[4/5] Inserting nodes (batch size: {})...", batch_size);
    let insert_start = Instant::now();
    
    let tx = conn.unchecked_transaction()?;
    
    let folder_count = folder_nodes.len();
    let file_count = file_nodes.len();
    let total_nodes = folder_count + file_count;
    let mut inserted = 0;
    
    for node in folder_nodes {
        insert_node(&conn, &node)?;
        inserted += 1;
        
        if inserted % batch_size == 0 {
            print!("\r      Inserted {}/{} nodes...", inserted, total_nodes);
            use std::io::Write;
            std::io::stdout().flush().ok();
        }
    }
    
    for node in file_nodes {
        insert_node(&conn, &node)?;
        
        if let Some(ref file_uuid) = node.file_uuid {
            let path = node.aliases.get("path").cloned().unwrap_or_default();
            if !path.is_empty() {
                conn.execute(
                    "INSERT OR IGNORE INTO file_locations (file_uuid, location, label, added_at)
                     VALUES (?1, ?2, 'origin', ?3)",
                    rusqlite::params![file_uuid, path, chrono::Utc::now().timestamp().to_string()],
                )?;
            }
        }
        
        inserted += 1;
        
        if inserted % batch_size == 0 {
            print!("\r      Inserted {}/{} nodes...", inserted, total_nodes);
            use std::io::Write;
            std::io::stdout().flush().ok();
        }
    }
    
    tx.commit()?;
    
    let insert_duration = insert_start.elapsed();
    println!("\r      Inserted {} nodes in {:.2}s ({:.0} nodes/sec)", 
        total_nodes,
        insert_duration.as_secs_f64(),
        total_nodes as f64 / insert_duration.as_secs_f64());
    
    println!();
    println!("[5/5] Updating folder children_json...");
    let children_start = Instant::now();
    
    conn.execute(
        "UPDATE file_nodes
         SET children_json = (
            SELECT json_group_array(node_id)
            FROM file_nodes AS child
            WHERE child.parent_id = file_nodes.node_id
         )
         WHERE node_type = 'folder'",
        [],
    )?;
    
    let children_duration = children_start.elapsed();
    println!("      Updated children_json for {} folders in {:.2}s",
        folder_count,
        children_duration.as_secs_f64());
    
    let total_duration = start.elapsed();
    println!();
    println!("=== Summary ===");
    println!("Total time: {:.2}s", total_duration.as_secs_f64());
    println!("Folders: {}", folder_count);
    println!("Files: {}", file_count);
    println!("Total nodes: {}", total_nodes);
    println!("Database: {}", FileTree::user_db_path(user_id));
    println!();
    println!("Performance breakdown:");
    println!("  - Scanning:      {:.2}s ({:.0}%)", 
        scan_duration.as_secs_f64(),
        scan_duration.as_secs_f64() / total_duration.as_secs_f64() * 100.0);
    println!("  - ID gen:        {:.2}s ({:.0}%)", 
        id_duration.as_secs_f64(),
        id_duration.as_secs_f64() / total_duration.as_secs_f64() * 100.0);
    println!("  - DB open:       {:.2}s ({:.0}%)", 
        db_duration.as_secs_f64(),
        db_duration.as_secs_f64() / total_duration.as_secs_f64() * 100.0);
    println!("  - Insertion:     {:.2}s ({:.0}%)", 
        insert_duration.as_secs_f64(),
        insert_duration.as_secs_f64() / total_duration.as_secs_f64() * 100.0);
    println!("  - Children JSON: {:.2}s ({:.0}%)", 
        children_duration.as_secs_f64(),
        children_duration.as_secs_f64() / total_duration.as_secs_f64() * 100.0);
    
    if !options.skip_hash {
        println!();
        println!("=== Starting background hash calculation ===");
        println!("Files to hash: {}", file_info.len());
        println!("Threads: {}", options.threads);
        
        let file_count = file_info.len();
        let hash_start = Instant::now();
        compute_hashes_parallel(user_id, file_info, options.threads)?;
        
        let hash_duration = hash_start.elapsed();
        println!();
        println!("Hash calculation completed in {:.2}s ({:.0} files/sec)",
            hash_duration.as_secs_f64(),
            file_count as f64 / hash_duration.as_secs_f64());
    } else {
        println!();
        println!("ℹ️  SHA256 hashes skipped. Run 'markbase hash --user {}' to compute hashes.", user_id);
    }
    
    Ok(())
}

pub fn compute_hashes(user_id: &str, threads: usize) -> Result<()> {
    println!("=== Background Hash Calculation ===");
    println!("User ID: {}", user_id);
    println!("Threads: {}", threads);
    println!();
    
    let conn = FileTree::open_user_db(user_id)?;
    
    let file_info: Vec<(String, String)> = conn
        .prepare("SELECT node_id, aliases_json FROM file_nodes WHERE node_type = 'file' AND sha256 IS NULL")?
        .query_map([], |row| {
            let node_id: String = row.get(0)?;
            let aliases_json: String = row.get(1)?;
            let aliases: HashMap<String, String> = serde_json::from_str(&aliases_json).unwrap_or_default();
            let path = aliases.get("path").cloned().unwrap_or_default();
            Ok((node_id, path))
        })?
        .filter_map(|r| r.ok())
        .filter(|(_, path)| !path.is_empty())
        .collect();
    
    if file_info.is_empty() {
        println!("No files need hashing. All files already have SHA256.");
        return Ok(());
    }
    
    println!("Files to hash: {}", file_info.len());
    
    let file_count = file_info.len();
    let start = Instant::now();
    compute_hashes_parallel(user_id, file_info, threads)?;
    
    let duration = start.elapsed();
    println!();
    println!("Hash calculation completed in {:.2}s ({:.0} files/sec)",
        duration.as_secs_f64(),
        file_count as f64 / duration.as_secs_f64());
    
    Ok(())
}

fn compute_hashes_parallel(user_id: &str, file_info: Vec<(String, String)>, threads: usize) -> Result<()> {
    let db_path = FileTree::user_db_path(user_id);
    let user_id = user_id.to_string();
    let file_info = Arc::new(file_info);
    let results: Arc<Mutex<HashMap<String, String>>> = Arc::new(Mutex::new(HashMap::new()));
    let processed: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
    let total = file_info.len();
    
    let mut handles = Vec::new();
    
    for i in 0..threads {
        let file_info = Arc::clone(&file_info);
        let results = Arc::clone(&results);
        let processed = Arc::clone(&processed);
        let user_id = user_id.clone();
        
        let handle = thread::spawn(move || {
            let chunk_size = (file_info.len() / threads) + (if i < file_info.len() % threads { 1 } else { 0 });
            let start_idx = i * (file_info.len() / threads) + i.min(file_info.len() % threads);
            let _end_idx = start_idx + chunk_size;
            
            for (node_id, path_str) in file_info.iter().skip(start_idx).take(chunk_size) {
                if let Ok(hash) = compute_file_hash(path_str) {
                    results.lock().unwrap().insert(node_id.clone(), hash);
                }
                
                let mut p = processed.lock().unwrap();
                *p += 1;
                if *p % 100 == 0 {
                    print!("\r      Hashed {}/{} files...", *p, total);
                    use std::io::Write;
                    std::io::stdout().flush().ok();
                }
            }
        });
        
        handles.push(handle);
    }
    
    for handle in handles {
        handle.join().expect("Thread panicked");
    }
    
    println!("\r      Hashed {}/{} files...Done", total, total);
    
    let results = results.lock().unwrap();
    let conn = Connection::open(&db_path)?;
    
    let tx = conn.unchecked_transaction()?;
    
    for (node_id, hash) in results.iter() {
        conn.execute(
            "UPDATE file_nodes SET sha256 = ?1, file_uuid = ?1, updated_at = ?2 WHERE node_id = ?3",
            rusqlite::params![hash, chrono::Utc::now().timestamp().to_string(), node_id],
        )?;
    }
    
    tx.commit()?;
    
    println!("      Updated {} hashes in database", results.len());
    
    Ok(())
}

fn scan_recursive(
    base: &Path,
    current: &Path,
    folders: &mut Vec<(String, String, Option<String>)>,
    files: &mut Vec<(String, String, u64, String)>,
) -> Result<()> {
    let entries: Vec<_> = fs::read_dir(current)?
        .filter_map(|e| e.ok())
        .filter(|e| e.file_name() != ".DS_Store")
        .collect();
    
    for entry in entries {
        let path = entry.path();
        let path_str = path.to_string_lossy().to_string();
        let filename = entry.file_name().to_string_lossy().to_string();
        
        if path.is_dir() {
            let parent_id = if path.parent() == Some(base) {
                None
            } else {
                find_parent_folder_id(&path_str, folders)
            };
            
            folders.push((path_str.clone(), filename, parent_id));
            
            scan_recursive(base, &path, folders, files)?;
        } else {
            let metadata = entry.metadata()?;
            let size = metadata.len();
            let ext = path.extension()
                .and_then(|s| s.to_str())
                .unwrap_or("")
                .to_string();
            
            files.push((path_str, filename, size, ext));
        }
    }
    
    Ok(())
}

fn compute_file_hash(path: &str) -> Result<String> {
    let mut hasher = Sha256::new();
    let mut file = fs::File::open(path)?;
    let mut buffer = [0u8; 8192];
    
    loop {
        let n = std::io::Read::read(&mut file, &mut buffer)?;
        if n == 0 {
            break;
        }
        hasher.update(&buffer[..n]);
    }
    
    let hash = format!("{:x}", hasher.finalize());
    Ok(hash.chars().take(32).collect())
}

fn generate_uuid(path: &str, filename: &str, mac: &str, mtime: u64) -> String {
    let mut hasher = Sha256::new();
    hasher.update(path.as_bytes());
    hasher.update(filename.as_bytes());
    hasher.update(mac.as_bytes());
    hasher.update(mtime.to_string().as_bytes());
    format!("{:x}", hasher.finalize()).chars().take(32).collect()
}

fn get_mac_address() -> Result<String> {
    let output = std::process::Command::new("ifconfig")
        .arg("en0")
        .output()?;
    
    let stdout = String::from_utf8_lossy(&output.stdout);
    for line in stdout.lines() {
        if line.contains("ether") {
            if let Some(mac) = line.split_whitespace().nth(1) {
                return Ok(mac.to_string());
            }
        }
    }
    
    Ok("00:00:00:00:00:00".to_string())
}

fn find_parent_folder(
    file_path: &str,
    _base: &Path,
    folders: &[(String, String, Option<String>)],
) -> Option<String> {
    let file_dir = Path::new(file_path).parent()?;
    
    for (folder_path, _, folder_id) in folders {
        if Path::new(folder_path) == file_dir {
            return folder_id.clone();
        }
    }
    
    None
}

fn find_parent_folder_id(path: &str, folders: &[(String, String, Option<String>)]) -> Option<String> {
    let current = Path::new(path);
    let parent = current.parent()?;
    let parent_str = parent.to_string_lossy();
    
    for (folder_path, _, folder_id) in folders {
        if folder_path == &parent_str {
            return folder_id.clone();
        }
    }
    
    None
}

fn insert_node(conn: &Connection, node: &FileNode) -> Result<()> {
    conn.execute(
        "INSERT OR REPLACE INTO file_nodes (
            node_id, label, aliases_json, file_uuid, sha256, parent_id, children_json,
            node_type, icon, color, bg_color, file_size, registered_at,
            created_at, updated_at, sort_order
        ) VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10, ?11, ?12, ?13, ?14, ?15, ?16)",
        rusqlite::params![
            node.node_id,
            node.label,
            node.aliases.to_json(),
            node.file_uuid,
            node.sha256,
            node.parent_id,
            serde_json::to_string(&node.children)?,
            node.node_type.as_str(),
            node.icon,
            node.color,
            node.bg_color,
            node.file_size,
            node.registered_at,
            node.created_at,
            node.updated_at,
            node.sort_order,
        ],
    )?;
    
    Ok(())
}

fn get_file_icon(filename: &str) -> Option<String> {
    let ext = Path::new(filename)
        .extension()
        .and_then(|s| s.to_str())
        .unwrap_or("")
        .to_lowercase();
    
    let icon = match ext.as_str() {
        "mp4" | "mov" | "avi" | "mkv" | "webm" => "🎬",
        "jpg" | "jpeg" | "png" | "gif" | "webp" | "svg" => "🖼️",
        "pdf" => "📄",
        "doc" | "docx" => "📝",
        "xls" | "xlsx" => "📊",
        "ppt" | "pptx" => "📽️",
        "zip" | "rar" | "7z" | "tar" | "gz" => "📦",
        "mp3" | "wav" | "flac" | "aac" => "🎵",
        "txt" | "md" => "📃",
        _ => "📄",
    };
    
    Some(icon.to_string())
}