//! Symlink management for NaK prefixes
//!
//! Creates symlinks FROM NaK prefix TO game prefixes.
//! Data stays in the game prefix, NaK just has links pointing to it.
//!
//! This inverted approach means:
//! - Game saves remain in their original location (Steam cloud sync works)
//! - NaK prefix provides unified access to all game data
//! - No data duplication or sync issues
//!
//! NaK Tools folder contains convenience symlinks pointing INTO the prefix
//! for easy access to Documents, AppData, etc.

// Allow unused items - some functions are public API for future use
#![allow(dead_code)]

use std::fs;
use std::path::Path;

use crate::game_finder::{detect_all_games, Game, GameScanResult};
use crate::logging::{log_info, log_warning};

// ============================================================================
// Public API
// ============================================================================

/// Create symlinks from NaK prefix to game prefixes for all detected games
///
/// This creates symlinks in the NaK prefix pointing to the actual save/config
/// folders in each game's own prefix. The symlink direction is:
///
/// NaK/Documents/My Games/Skyrim -> game_prefix/Documents/My Games/Skyrim
/// NaK/AppData/Local/Skyrim -> game_prefix/AppData/Local/Skyrim
///
/// Data stays in the game prefix (preserving Steam Cloud sync), while NaK
/// provides unified access through symlinks.
pub fn create_game_symlinks(nak_prefix: &Path, games: &[Game]) {
    let users_dir = nak_prefix.join("drive_c/users");
    let username = find_prefix_username(&users_dir);
    let user_dir = users_dir.join(&username);

    let documents = user_dir.join("Documents");
    let my_games = documents.join("My Games");
    let appdata_local = user_dir.join("AppData/Local");
    let appdata_roaming = user_dir.join("AppData/Roaming");

    // Ensure base directories exist (real folders in NaK prefix)
    let _ = fs::create_dir_all(&my_games);
    let _ = fs::create_dir_all(&appdata_local);
    let _ = fs::create_dir_all(&appdata_roaming);

    let mut linked_count = 0;

    for game in games {
        // Skip games without prefixes
        let Some(game_prefix) = &game.prefix_path else {
            log_info(&format!(
                "Symlink skip '{}' (app_id {}): no prefix_path",
                game.name, game.app_id
            ));
            continue;
        };

        // Discover the game prefix's user directory
        let game_users_dir = game_prefix.join("drive_c/users");
        let game_username = find_prefix_username(&game_users_dir);
        let game_user_dir = game_users_dir.join(&game_username);

        let my_games_dir = game_user_dir.join("Documents/My Games");
        log_info(&format!(
            "Symlink checking '{}' (app_id {}): prefix={}, user='{}', my_games_exists={}",
            game.name, game.app_id, game_prefix.display(), game_username, my_games_dir.is_dir()
        ));

        // Scan and symlink ALL folders in the game prefix's Documents/My Games/
        linked_count += scan_and_link_all(
            &my_games,
            &game_user_dir.join("Documents/My Games"),
            "Documents/My Games",
            &game.name,
            game_prefix,
        );

        // Also link the Documents folder itself for non-My Games entries
        // (some games put saves directly in Documents/<GameName>)
        linked_count += scan_and_link_all(
            &documents,
            &game_user_dir.join("Documents"),
            "Documents",
            &game.name,
            game_prefix,
        );

        // Scan and symlink ALL folders in AppData/Local/
        linked_count += scan_and_link_all(
            &appdata_local,
            &game_user_dir.join("AppData/Local"),
            "AppData/Local",
            &game.name,
            game_prefix,
        );

        // Scan and symlink ALL folders in AppData/Roaming/
        linked_count += scan_and_link_all(
            &appdata_roaming,
            &game_user_dir.join("AppData/Roaming"),
            "AppData/Roaming",
            &game.name,
            game_prefix,
        );
    }

    if linked_count > 0 {
        log_info(&format!(
            "Created {} symlinks to game prefixes",
            linked_count
        ));
    }

    // Create "My Documents" symlink for compatibility
    let my_documents = user_dir.join("My Documents");
    if !my_documents.exists() && fs::symlink_metadata(&my_documents).is_err() {
        if let Err(e) = std::os::unix::fs::symlink("Documents", &my_documents) {
            log_warning(&format!("Failed to create My Documents symlink: {}", e));
        }
    }
}

/// Create NaK Tools convenience symlinks pointing INTO the prefix
///
/// Creates symlinks in NaK Tools folder for easy access:
/// - NaK Tools/Prefix Documents -> prefix/drive_c/users/<user>/Documents
/// - NaK Tools/Prefix AppData Local -> prefix/drive_c/users/<user>/AppData/Local
/// - NaK Tools/Prefix AppData Roaming -> prefix/drive_c/users/<user>/AppData/Roaming
pub fn create_nak_tools_symlinks(tools_dir: &Path, prefix_path: &Path) {
    let users_dir = prefix_path.join("drive_c/users");
    let username = find_prefix_username(&users_dir);
    let user_dir = users_dir.join(&username);

    // Symlink: NaK Tools/Prefix Documents -> prefix Documents
    let documents_link = tools_dir.join("Prefix Documents");
    let documents_target = user_dir.join("Documents");
    create_or_update_symlink(&documents_link, &documents_target, "Prefix Documents");

    // Symlink: NaK Tools/Prefix AppData Local -> prefix AppData/Local
    let appdata_local_link = tools_dir.join("Prefix AppData Local");
    let appdata_local_target = user_dir.join("AppData/Local");
    create_or_update_symlink(&appdata_local_link, &appdata_local_target, "Prefix AppData Local");

    // Symlink: NaK Tools/Prefix AppData Roaming -> prefix AppData/Roaming
    let appdata_roaming_link = tools_dir.join("Prefix AppData Roaming");
    let appdata_roaming_target = user_dir.join("AppData/Roaming");
    create_or_update_symlink(&appdata_roaming_link, &appdata_roaming_target, "Prefix AppData Roaming");

    log_info("Created NaK Tools convenience symlinks to prefix folders");
}

/// Create or update a symlink
fn create_or_update_symlink(link_path: &Path, target: &Path, name: &str) {
    // Remove existing symlink or file
    if link_path.exists() || fs::symlink_metadata(link_path).is_ok() {
        let _ = fs::remove_file(link_path);
        let _ = fs::remove_dir_all(link_path);
    }

    // Create symlink
    if let Err(e) = std::os::unix::fs::symlink(target, link_path) {
        log_warning(&format!("Failed to create {} symlink: {}", name, e));
    }
}

/// Create symlinks for all detected games
///
/// Convenience function that detects games and creates symlinks in one call.
pub fn create_game_symlinks_auto(nak_prefix: &Path) -> GameScanResult {
    let result = detect_all_games();
    create_game_symlinks(nak_prefix, &result.games);
    result
}

/// Ensure only the Temp directory exists in AppData/Local
///
/// MO2 and other tools require AppData/Local/Temp to exist.
/// We create only this essential directory, leaving other game-specific
/// folders to be symlinked from game prefixes.
pub fn ensure_temp_directory(prefix_path: &Path) {
    let users_dir = prefix_path.join("drive_c/users");
    let username = find_prefix_username(&users_dir);
    let user_dir = users_dir.join(&username);

    let temp_dir = user_dir.join("AppData/Local/Temp");
    if let Err(e) = fs::create_dir_all(&temp_dir) {
        log_warning(&format!("Failed to create Temp directory: {}", e));
    } else {
        log_info("Ensured AppData/Local/Temp directory exists");
    }
}

// ============================================================================
// Internal Functions
// ============================================================================

/// Directories to skip when scanning prefix folders for symlinking.
/// These are Wine/Proton internal or system dirs, not game data.
const SKIP_DIRS: &[&str] = &[
    "Temp", "Microsoft", "wine", "Public", "root",
    "Application Data", "Cookies", "Local Settings",
    "NetHood", "PrintHood", "Recent", "SendTo",
    "Start Menu", "Templates", "My Documents", "My Music",
    "My Pictures", "My Videos", "Desktop", "Downloads",
    "Favorites", "Links", "Searches",
    "Contacts", "3D Objects",
];

/// Scan all subdirectories in a game prefix folder and create symlinks
/// for each one in the corresponding NaK prefix folder.
///
/// Returns the number of symlinks created.
fn scan_and_link_all(
    nak_base: &Path,
    game_base: &Path,
    label: &str,
    game_name: &str,
    _game_prefix: &Path,
) -> usize {
    if !game_base.is_dir() {
        log_info(&format!(
            "  scan_and_link_all: {} not a dir for '{}', skipping",
            game_base.display(), game_name
        ));
        return 0;
    }

    let Ok(entries) = fs::read_dir(game_base) else {
        log_info(&format!(
            "  scan_and_link_all: cannot read {} for '{}'",
            game_base.display(), game_name
        ));
        return 0;
    };

    let mut count = 0;
    for entry in entries.flatten() {
        // Only symlink directories (game folders), not loose files
        if !entry.path().is_dir() {
            continue;
        }

        let folder_name = entry.file_name().to_string_lossy().to_string();

        // Skip Wine/system internal directories
        if SKIP_DIRS.iter().any(|&s| s.eq_ignore_ascii_case(&folder_name)) {
            continue;
        }

        // Skip if it's "My Games" and we're scanning Documents (handled separately)
        if label == "Documents" && folder_name == "My Games" {
            continue;
        }

        let nak_path = nak_base.join(&folder_name);
        let source_path = entry.path();

        if create_symlink_if_needed(&nak_path, &source_path, game_name, label, &folder_name) {
            count += 1;
        }
    }

    count
}

/// Create a symlink if the target doesn't already exist or is already correct.
///
/// Returns true if a symlink was created (or already existed correctly).
fn create_symlink_if_needed(
    nak_path: &Path,
    source_path: &Path,
    game_name: &str,
    label: &str,
    folder_name: &str,
) -> bool {
    // Check if target already exists
    if nak_path.exists() || fs::symlink_metadata(nak_path).is_ok() {
        // Check if it's already a symlink to the correct location
        if let Ok(target) = fs::read_link(nak_path) {
            if target == source_path {
                return true; // Already correctly linked
            }
        }
        // Something else exists here, don't overwrite
        return false;
    }

    // Ensure parent directory exists
    if let Some(parent) = nak_path.parent() {
        let _ = fs::create_dir_all(parent);
    }

    // Create the symlink
    match std::os::unix::fs::symlink(source_path, nak_path) {
        Ok(()) => {
            log_info(&format!(
                "Linked {}/{} -> {} ({})",
                label,
                folder_name,
                source_path.display(),
                game_name,
            ));
            true
        }
        Err(e) => {
            log_warning(&format!(
                "Failed to create symlink for {} ({}/{}): {}",
                game_name, label, folder_name, e
            ));
            false
        }
    }
}

/// Find the username from a Wine prefix users directory
fn find_prefix_username(users_dir: &Path) -> String {
    if let Ok(entries) = fs::read_dir(users_dir) {
        for entry in entries.flatten() {
            let name = entry.file_name().to_string_lossy().to_string();
            if name != "Public" && name != "root" {
                return name;
            }
        }
    }
    "steamuser".to_string()
}

// ============================================================================
// Oblivion Lowercase INI Symlinks
// ============================================================================

/// Create lowercase INI symlinks for Oblivion (some tools expect lowercase)
pub fn create_oblivion_ini_symlinks(prefix_path: &Path) {
    let users_dir = prefix_path.join("drive_c/users");
    let username = find_prefix_username(&users_dir);
    let oblivion_dir = users_dir
        .join(&username)
        .join("Documents/My Games/Oblivion");

    if !oblivion_dir.exists() {
        return;
    }

    create_lowercase_ini_symlink(&oblivion_dir, "Oblivion.ini", "oblivion.ini");
    create_lowercase_ini_symlink(&oblivion_dir, "OblivionPrefs.ini", "oblivionprefs.ini");
}

/// Create a lowercase symlink for an INI file
fn create_lowercase_ini_symlink(dir: &Path, original: &str, lowercase: &str) {
    let original_path = dir.join(original);
    let lowercase_path = dir.join(lowercase);

    // Only create if original exists and lowercase doesn't
    if original_path.exists()
        && !lowercase_path.exists()
        && fs::symlink_metadata(&lowercase_path).is_err()
    {
        // Create relative symlink (just the filename)
        if let Err(e) = std::os::unix::fs::symlink(original, &lowercase_path) {
            log_warning(&format!(
                "Failed to create lowercase symlink {} -> {}: {}",
                lowercase, original, e
            ));
        } else {
            log_info(&format!(
                "Created lowercase INI symlink: {} -> {}",
                lowercase, original
            ));
        }
    }
}