aria2-core 0.2.1

//! Session Entry module - Core data structure for session serialization
//!
//! This module provides the `SessionEntry` struct which represents a single download
//! task's state that can be serialized to and deserialized from session files.
//!
//! # Overview
//!
//! A `SessionEntry` captures all necessary information about an active or paused download:
//! - **URIs**: One or more source URLs (mirrors) for the download
//! - **GID**: Unique identifier for the download task
//! - **Options**: Download configuration options (split, dir, out, etc.)
//! - **Progress**: Current download/upload statistics
//! - **Status**: Active state of the download (active, waiting, paused, error)
//! - **BT-specific**: Bitfield and piece information for BitTorrent downloads
//!
//! # Architecture
//!
//! ```text
//! session_entry.rs (this file)
//!   ├── SessionEntry struct definition
//!   ├── Builder pattern methods (new, with_options, paused)
//!   └── Re-exports for convenience
//!
//! session_serialize_impl.rs
//!   └── impl SessionEntry { serialize(), deserialize_line() }
//!
//! session_uri_utils.rs
//!   └── escape_uri(), unescape_uri(), decode_hex()
//!
//! session_options.rs
//!   └── download_options_to_map()
//! ```
//!
//! # Examples
//!
//! ```rust
//! use aria2_core::session::session_entry::SessionEntry;
//! use std::collections::HashMap;
//!
//! // Create a basic entry
//! let entry = SessionEntry::new(1, vec!["http://example.com/file.zip".to_string()]);
//!
//! // Add options using builder pattern
//! let entry = SessionEntry::new(2, vec!["http://example.com/big.iso".to_string()])
//!     .with_options({
//!         let mut opts = HashMap::new();
//!         opts.insert("split".to_string(), "4".to_string());
//!         opts.insert("dir".to_string(), "/downloads".to_string());
//!         opts
//!     })
//!     .paused();
//! ```

use std::collections::HashMap;

use crate::error::{Aria2Error, Result};
use crate::request::request_group::DownloadOptions;

// =========================================================================
// URI Utility Functions (consolidated from session_uri_utils.rs)
// =========================================================================

/// Escapes special characters in URIs for safe serialization.
pub fn escape_uri(s: &str) -> String {
    s.replace('\\', "\\\\")
        .replace('\t', "\\t")
        .replace('\n', "\\n")
}

/// Unescapes special characters previously escaped by [`escape_uri()`].
pub fn unescape_uri(s: &str) -> String {
    let mut result = String::with_capacity(s.len());
    let mut chars = s.chars().peekable();

    while let Some(c) = chars.next() {
        if c == '\\' {
            if let Some(&next) = chars.peek() {
                match next {
                    't' => {
                        result.push('\t');
                        chars.next();
                    }
                    'n' => {
                        result.push('\n');
                        chars.next();
                    }
                    '\\' => {
                        result.push('\\');
                        chars.next();
                    }
                    _ => {
                        result.push(c);
                    }
                }
            } else {
                result.push(c);
            }
        } else {
            result.push(c);
        }
    }

    result
}

/// Decodes a hexadecimal string to a byte vector.
pub fn decode_hex(hex: &str) -> Result<Vec<u8>> {
    if !hex.len().is_multiple_of(2) {
        return Err(Aria2Error::Io(format!(
            "Hex string has odd length: {}",
            hex.len()
        )));
    }

    let mut bytes = Vec::with_capacity(hex.len() / 2);

    for i in (0..hex.len()).step_by(2) {
        let byte_str = &hex[i..i + 2];
        let byte = u8::from_str_radix(byte_str, 16).map_err(|e| {
            Aria2Error::Io(format!("Invalid hex character at position {}: {}", i, e))
        })?;
        bytes.push(byte);
    }

    Ok(bytes)
}

// =========================================================================
// Options Conversion (consolidated from session_options.rs)
// =========================================================================

/// Converts DownloadOptions struct to a HashMap for serialization.
///
/// Only non-default / non-empty values are included to keep the session file
/// compact. The load path (`map_entry_to_download_options`) uses
/// `unwrap_or(default)` for every field, so absent keys are safe.
pub fn download_options_to_map(opts: &DownloadOptions) -> HashMap<String, String> {
    let mut map = HashMap::new();

    // --- Basic download options ---
    if let Some(v) = opts.split {
        map.insert("split".to_string(), v.to_string());
    }
    if let Some(v) = opts.max_connection_per_server {
        map.insert("max-connection-per-server".to_string(), v.to_string());
    }
    if let Some(v) = opts.max_download_limit {
        map.insert("max-download-limit".to_string(), v.to_string());
    }
    if let Some(v) = opts.max_upload_limit {
        map.insert("max-upload-limit".to_string(), v.to_string());
    }
    if let Some(ref v) = opts.dir {
        map.insert("dir".to_string(), v.clone());
    }
    if let Some(ref v) = opts.out {
        map.insert("out".to_string(), v.clone());
    }
    if let Some(v) = opts.seed_time {
        map.insert("seed-time".to_string(), v.to_string());
    }
    if let Some(v) = opts.seed_ratio {
        map.insert("seed-ratio".to_string(), v.to_string());
    }

    // --- File allocation ---
    if let Some(ref v) = opts.file_allocation {
        map.insert("file-allocation".to_string(), v.clone());
    }
    if let Some(v) = opts.mmap_threshold {
        map.insert("mmap-threshold".to_string(), v.to_string());
    }
    if opts.secure_falloc {
        map.insert("secure-falloc".to_string(), "true".to_string());
    }

    // --- Checksum ---
    if let Some((ref algo, ref val)) = opts.checksum {
        map.insert("checksum".to_string(), format!("{}={}", algo, val));
    }

    // --- Cookies ---
    if let Some(ref v) = opts.cookie_file {
        map.insert("cookie-file".to_string(), v.clone());
    }
    if let Some(ref v) = opts.cookies {
        map.insert("cookies".to_string(), v.clone());
    }

    // --- BitTorrent options ---
    if opts.bt_force_encrypt {
        map.insert("bt-force-encrypt".to_string(), "true".to_string());
    }
    if opts.bt_require_crypto {
        map.insert("bt-require-crypto".to_string(), "true".to_string());
    }
    // enable_dht defaults to true; only save if disabled
    if !opts.enable_dht {
        map.insert("enable-dht".to_string(), "false".to_string());
    }
    if let Some(v) = opts.dht_listen_port {
        map.insert("dht-listen-port".to_string(), v.to_string());
    }
    if let Some(ref v) = opts.dht_entry_point {
        map.insert("dht-entry-point".to_string(), v.join(","));
    }
    // enable_public_trackers defaults to true; only save if disabled
    if !opts.enable_public_trackers {
        map.insert("enable-public-trackers".to_string(), "false".to_string());
    }
    if !opts.bt_piece_selection_strategy.is_empty() {
        map.insert(
            "bt-piece-selection-strategy".to_string(),
            opts.bt_piece_selection_strategy.clone(),
        );
    }
    if opts.bt_endgame_threshold > 0 {
        map.insert(
            "bt-endgame-threshold".to_string(),
            opts.bt_endgame_threshold.to_string(),
        );
    }
    if let Some(v) = opts.bt_max_upload_slots {
        map.insert("bt-max-upload-slots".to_string(), v.to_string());
    }
    if let Some(v) = opts.bt_optimistic_unchoke_interval {
        map.insert("bt-optimistic-unchoke-interval".to_string(), v.to_string());
    }
    if let Some(v) = opts.bt_snubbed_timeout {
        map.insert("bt-snubbed-timeout".to_string(), v.to_string());
    }
    if !opts.bt_prioritize_piece.is_empty() {
        map.insert(
            "bt-prioritize-piece".to_string(),
            opts.bt_prioritize_piece.clone(),
        );
    }
    if opts.enable_utp {
        map.insert("enable-utp".to_string(), "true".to_string());
    }
    if let Some(v) = opts.utp_listen_port {
        map.insert("utp-listen-port".to_string(), v.to_string());
    }

    // --- Retry options ---
    if opts.max_retries > 0 {
        map.insert("max-retries".to_string(), opts.max_retries.to_string());
    }
    if opts.retry_wait > 0 {
        map.insert("retry-wait".to_string(), opts.retry_wait.to_string());
    }

    // --- DHT file path ---
    if let Some(ref v) = opts.dht_file_path {
        map.insert("dht-file-path".to_string(), v.clone());
    }

    // --- Proxy options ---
    if let Some(ref v) = opts.http_proxy {
        map.insert("http-proxy".to_string(), v.clone());
    }
    if let Some(ref v) = opts.all_proxy {
        map.insert("all-proxy".to_string(), v.clone());
    }
    if let Some(ref v) = opts.https_proxy {
        map.insert("https-proxy".to_string(), v.clone());
    }
    if let Some(ref v) = opts.ftp_proxy {
        map.insert("ftp-proxy".to_string(), v.clone());
    }
    if let Some(ref v) = opts.no_proxy {
        map.insert("no-proxy".to_string(), v.clone());
    }

    // --- HTTP headers ---
    if !opts.header.is_empty() {
        map.insert("header".to_string(), opts.header.join(","));
    }
    if let Some(ref v) = opts.user_agent {
        map.insert("user-agent".to_string(), v.clone());
    }
    if let Some(ref v) = opts.referer {
        map.insert("referer".to_string(), v.clone());
    }

    map
}

/// Represents a single download task in a session file
///
/// This struct contains all information needed to resume a download task,
/// including URIs, options, current progress, and status.
///
/// # Fields
///
/// * `gid` - Unique global identifier for this download task
/// * `uris` - List of source URLs (primary URL + mirrors)
/// * `options` - Download configuration options as key-value pairs
/// * `paused` - Whether this download is currently paused
/// * `total_length` - Total size of the download in bytes
/// * `completed_length` - Number of bytes already downloaded
/// * `upload_length` - Number of bytes uploaded (for seeding)
/// * `download_speed` - Current download speed in bytes/sec
/// * `status` - Current status: "active", "waiting", "paused", or "error"
/// * `error_code` - Error code if status is "error"
/// * `bitfield` - BitTorrent piece completion bitmap (BT only)
/// * `num_pieces` - Number of pieces in torrent (BT only)
/// * `piece_length` - Size of each piece in bytes (BT only)
/// * `info_hash_hex` - Torrent info hash hex string (BT only)
/// * `resume_offset` - File offset for HTTP/FTP resume support
#[derive(Debug, Clone)]
pub struct SessionEntry {
    /// Unique global identifier for this download task
    pub gid: u64,

    /// List of source URIs (primary URL + mirrors), tab-separated in serialized form
    pub uris: Vec<String>,

    /// Download configuration options as key-value pairs
    pub options: HashMap<String, String>,

    /// Whether this download is currently paused
    pub paused: bool,

    // ==================== Progress & Status Fields ====================
    /// Total size of the download in bytes (0 if unknown)
    pub total_length: u64,

    /// Number of bytes already downloaded and verified
    pub completed_length: u64,

    /// Number of bytes uploaded (relevant for BitTorrent seeding)
    pub upload_length: u64,

    /// Current download speed in bytes/second
    pub download_speed: u64,

    /// Current status of the download: "active", "waiting", "paused", "error"
    pub status: String,

    /// Error code if the download is in error state
    pub error_code: Option<i32>,

    // ==================== BitTorrent-Specific Fields ====================
    // These fields are only populated for BitTorrent downloads
    /// Completed piece bitmap encoded as hex string in file format
    /// None for non-BT downloads
    pub bitfield: Option<Vec<u8>>,

    /// Total number of pieces in the torrent
    /// None for non-BT downloads
    pub num_pieces: Option<u32>,

    /// Size of each piece in bytes
    /// None for non-BT downloads
    pub piece_length: Option<u32>,

    /// Info hash of the torrent (hex string) for matching torrent files
    /// None for non-BT downloads
    pub info_hash_hex: Option<String>,

    // ==================== HTTP/FTP Resume Support ====================
    /// File offset where download should resume (for HTTP/FTP range requests)
    /// None if resumption is not applicable
    pub resume_offset: Option<u64>,
}

impl SessionEntry {
    /// Creates a new SessionEntry with default values
    ///
    /// # Arguments
    ///
    /// * `gid` - Unique identifier for this download task
    /// * `uris` - List of source URLs (at least one required)
    ///
    /// # Returns
    ///
    /// A new `SessionEntry` instance with sensible defaults:
    /// - `paused`: false
    /// - All progress fields: 0
    /// - `status`: "active"
    /// - All optional fields: None
    ///
    /// # Example
    ///
    /// ```rust
    /// use aria2_core::session::session_entry::SessionEntry;
    ///
    /// let entry = SessionEntry::new(1, vec!["http://example.com/file.zip".to_string()]);
    /// assert_eq!(entry.gid, 1);
    /// assert_eq!(entry.uris.len(), 1);
    /// assert!(!entry.paused);
    /// assert_eq!(entry.status, "active");
    /// ```
    pub fn new(gid: u64, uris: Vec<String>) -> Self {
        SessionEntry {
            gid,
            uris,
            options: HashMap::new(),
            paused: false,

            // Default values for progress fields
            total_length: 0,
            completed_length: 0,
            upload_length: 0,
            download_speed: 0,
            status: "active".to_string(),
            error_code: None,

            // BT-specific fields (None for non-BT downloads by default)
            bitfield: None,
            num_pieces: None,
            piece_length: None,
            info_hash_hex: None,

            // HTTP/FTP resume info (None by default)
            resume_offset: None,
        }
    }

    /// Sets download options using builder pattern
    ///
    /// # Arguments
    ///
    /// * `options` - HashMap of option key-value pairs
    ///
    /// # Returns
    ///
    /// Self for method chaining
    ///
    /// # Example
    ///
    /// ```rust
    /// use aria2_core::session::session_entry::SessionEntry;
    /// use std::collections::HashMap;
    ///
    /// let mut opts = HashMap::new();
    /// opts.insert("split".to_string(), "4".to_string());
    /// opts.insert("dir".to_string(), "/downloads".to_string());
    ///
    /// let entry = SessionEntry::new(1, vec!["http://example.com/f".to_string()])
    ///     .with_options(opts);
    /// assert_eq!(entry.options.get("split").unwrap(), "4");
    /// ```
    pub fn with_options(mut self, options: HashMap<String, String>) -> Self {
        self.options = options;
        self
    }

    /// Marks this entry as paused using builder pattern
    ///
    /// # Returns
    ///
    /// Self for method chaining
    ///
    /// # Example
    ///
    /// ```no_run
    /// use aria2_core::session::session_entry::SessionEntry;
    ///
    /// let entry = SessionEntry::new(1, vec!["http://example.com/f".to_string()])
    ///     .paused();
    /// assert!(entry.paused);
    /// ```
    pub fn paused(mut self) -> Self {
        self.paused = true;
        self
    }

    /// Gets an option value by key
    ///
    /// # Arguments
    ///
    /// * `key` - Option key to look up
    ///
    /// # Returns
    ///
    /// Some(&str) if the key exists, None otherwise
    #[allow(dead_code)] // Utility method for option retrieval, available for future use
    fn get_option(&self, key: &str) -> Option<&str> {
        self.options.get(key).map(|s| s.as_str())
    }

    // Note: serialize() and deserialize_line() are now implemented in
    // session_serialize_impl.rs as part of impl SessionEntry
    // They are available via the impl block there and accessible normally
}

// ==================== Unit Tests ====================

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_serialize_single_entry() {
        let entry = SessionEntry::new(0xd270c8a2, vec!["http://example.com/file.zip".to_string()]);
        let text = entry.serialize();
        assert!(
            text.contains("http://example.com/file.zip"),
            "Should contain URI"
        );
        assert!(text.contains("GID=d270c8a2"), "Should contain GID");
    }

    #[test]
    fn test_serialize_multiple_entries_roundtrip() {
        let entries = vec![
            SessionEntry::new(1, vec!["http://a.com/1.bin".to_string()]).with_options({
                let mut m = HashMap::new();
                m.insert("split".to_string(), "4".to_string());
                m.insert("dir".to_string(), "/tmp".to_string());
                m
            }),
            SessionEntry::new(
                2,
                vec![
                    "ftp://b.com/2.iso".to_string(),
                    "http://mirror.b.com/2.iso".to_string(),
                ],
            )
            .paused(),
        ];

        let mut serialized = String::new();
        for e in &entries {
            serialized.push_str(&e.serialize());
            serialized.push('\n');
        }

        // Parse individually using deserialize_line
        let parts: Vec<&str> = serialized.split("\n\n").collect();
        assert!(parts.len() >= 2, "Should have at least 2 entries");

        let entry1 = SessionEntry::deserialize_line(parts[0]).unwrap();
        assert_eq!(entry1.uris.len(), 1);
        assert_eq!(entry1.uris[0], "http://a.com/1.bin");
        assert_eq!(entry1.options.get("split").unwrap(), "4");

        let entry2 = SessionEntry::deserialize_line(parts[1]).unwrap();
        assert_eq!(entry2.uris.len(), 2);
        assert!(entry2.paused);
    }

    #[test]
    fn test_deserialize_empty_file() {
        let entry = SessionEntry::deserialize_line("").unwrap();
        assert!(entry.uris.is_empty());

        let entry = SessionEntry::deserialize_line("\n\n\n").unwrap();
        assert!(entry.uris.is_empty());
    }

    #[test]
    fn test_deserialize_skip_comments_and_blanks() {
        let input = r#"# This is a comment
# Another comment

http://example.com/file
 GID=abc123
 dir=/downloads
"#;
        let entry = SessionEntry::deserialize_line(input).unwrap();
        // Should parse first entry and ignore comments
        assert_eq!(entry.uris.len(), 1);
        assert_eq!(entry.uris[0], "http://example.com/file");
    }

    #[test]
    fn test_deserialize_options_parsing() {
        let input = r#"http://example.com/file.zip
 GID=1
 split=4
 max-connection-per-server=2
 dir=C:\Users\test\Downloads
 out=file.zip
"#;
        let entry = SessionEntry::deserialize_line(input).unwrap();
        assert_eq!(entry.options.get("split").unwrap(), "4");
        assert_eq!(entry.options.get("max-connection-per-server").unwrap(), "2");
        assert_eq!(
            entry.options.get("dir").unwrap(),
            "C:\\Users\\test\\Downloads"
        );
        assert_eq!(entry.options.get("out").unwrap(), "file.zip");
    }

    #[test]
    fn test_pause_flag_serialization() {
        let input = r#"http://example.com/pause.me
 GID=42
 PAUSE=true
"#;
        let entry = SessionEntry::deserialize_line(input).unwrap();
        assert!(entry.paused);

        let text = entry.serialize();
        assert!(text.contains("PAUSE=true"));
    }

    #[test]
    fn test_serialize_tab_separated_uris() {
        let entry = SessionEntry::new(
            99,
            vec![
                "http://mirror1.com/f".to_string(),
                "http://mirror2.com/f".to_string(),
                "http://mirror3.com/f".to_string(),
            ],
        );
        let text = entry.serialize();
        let uri_line = text.lines().next().unwrap();
        assert_eq!(
            uri_line.matches('\t').count(),
            2,
            "3 URIs should have 2 tab separators"
        );
    }

    // ==================== New Field Tests (Session Persistence Enhancement) ====================

    #[test]
    fn test_serialize_new_fields() {
        let mut entry = SessionEntry::new(1, vec!["http://example.com/file.bin".to_string()]);
        entry.total_length = 1024 * 1024; // 1MB
        entry.completed_length = 512 * 1024; // 512KB
        entry.upload_length = 1024;
        entry.download_speed = 2048;
        entry.status = "active".to_string();
        entry.error_code = None;

        let text = entry.serialize();

        // Verify new fields appear in output
        assert!(
            text.contains("TOTAL_LENGTH=1048576"),
            "Should contain TOTAL_LENGTH"
        );
        assert!(
            text.contains("COMPLETED_LENGTH=524288"),
            "Should contain COMPLETED_LENGTH"
        );
        assert!(
            text.contains("UPLOAD_LENGTH=1024"),
            "Should contain UPLOAD_LENGTH"
        );
        assert!(
            text.contains("DOWNLOAD_SPEED=2048"),
            "Should contain DOWNLOAD_SPEED"
        );
        assert!(text.contains("STATUS=active"), "Should contain STATUS");
    }

    #[test]
    fn test_deserialize_with_all_fields() {
        let input = r#"http://example.com/bigfile.zip
 GID=1
 TOTAL_LENGTH=10485760
 COMPLETED_LENGTH=5242880
 UPLOAD_LENGTH=2048
 DOWNLOAD_SPEED=4096
 STATUS=active
 ERROR_CODE=
 BITFIELD=
 NUM_PIECES=0
 PIECE_LENGTH=0
 INFO_HASH=
 RESUME_OFFSET=5242880
"#;

        let entry = SessionEntry::deserialize_line(input).unwrap();

        assert_eq!(entry.total_length, 10485760);
        assert_eq!(entry.completed_length, 5242880);
        assert_eq!(entry.upload_length, 2048);
        assert_eq!(entry.download_speed, 4096);
        assert_eq!(entry.status, "active");
        assert_eq!(entry.error_code, None);
        assert_eq!(entry.resume_offset, Some(5242880));
    }

    #[test]
    fn test_deserialize_user_options() {
        // User-defined options should be stored in options map
        let input = r#"http://example.com/file.zip
 GID=1
 split=4
 dir=/downloads
 TOTAL_LENGTH=1000
"#;

        let entry = SessionEntry::deserialize_line(input).unwrap();

        // Known fields parsed normally
        assert_eq!(entry.total_length, 1000);

        // User options stored in options
        assert_eq!(entry.options.get("split").unwrap(), "4");
        assert_eq!(entry.options.get("dir").unwrap(), "/downloads");
    }

    #[test]
    fn test_bitfield_roundtrip() {
        let mut entry =
            SessionEntry::new(1, vec!["http://example.com/torrent.torrent".to_string()]);

        // Set bitfield: [0xFF, 0xF0, 0x0F] - indicates some pieces completed
        entry.bitfield = Some(vec![0xFF, 0xF0, 0x0F]);
        entry.num_pieces = Some(24); // 3 bytes * 8 bits = 24 pieces
        entry.piece_length = Some(262144); // 256KB

        let text = entry.serialize();

        // Verify hex encoding
        assert!(
            text.contains("BITFIELD=fff00f"),
            "bitfield should be encoded as hex string"
        );

        // Deserialize verification
        let restored = SessionEntry::deserialize_line(&text).unwrap();
        assert_eq!(
            restored.bitfield,
            Some(vec![0xFF, 0xF0, 0x0F]),
            "bitfield should be restored correctly"
        );
        assert_eq!(restored.num_pieces, Some(24));
        assert_eq!(restored.piece_length, Some(262144));
    }

    #[test]
    fn test_empty_bitfield_serialized_as_empty() {
        let entry = SessionEntry::new(1, vec!["http://example.com/file.zip".to_string()]);
        // bitfield defaults to None

        let text = entry.serialize();

        // None bitfield should produce empty value
        assert!(
            text.contains("BITFIELD=\n"),
            "None bitfield should be serialized as empty value"
        );

        // Deserialize verification
        let restored = SessionEntry::deserialize_line(&text).unwrap();
        assert_eq!(
            restored.bitfield, None,
            "Empty bitfield should restore to None"
        );
    }

    #[test]
    fn test_default_session_entry_has_zero_progress() {
        let entry = SessionEntry::new(99, vec!["http://test.com/f".to_string()]);

        // Verify all new fields have correct defaults
        assert_eq!(entry.total_length, 0);
        assert_eq!(entry.completed_length, 0);
        assert_eq!(entry.upload_length, 0);
        assert_eq!(entry.download_speed, 0);
        assert_eq!(entry.status, "active", "Default status should be 'active'");
        assert_eq!(entry.error_code, None);
        assert_eq!(entry.bitfield, None);
        assert_eq!(entry.num_pieces, None);
        assert_eq!(entry.piece_length, None);
        assert_eq!(entry.info_hash_hex, None);
        assert_eq!(entry.resume_offset, None);
    }

    #[test]
    fn test_status_field_values() {
        let statuses = ["active", "waiting", "paused", "error"];

        for status in statuses {
            let mut entry = SessionEntry::new(1, vec!["http://example.com/f".to_string()]);
            entry.status = status.to_string();

            let text = entry.serialize();
            assert!(
                text.contains(&format!("STATUS={}", status)),
                "Status '{}' should be serialized correctly",
                status
            );

            // Deserialize verification
            let restored = SessionEntry::deserialize_line(&text).unwrap();
            assert_eq!(
                restored.status, status,
                "Status '{}' should be deserialized correctly",
                status
            );
        }
    }

    #[test]
    fn test_resume_offset_for_http_ftp() {
        let mut entry = SessionEntry::new(1, vec!["http://example.com/large-file.iso".to_string()]);

        // Simulate HTTP download with partial data written
        entry.total_length = 1073741824; // 1GB
        entry.completed_length = 536870912; // 512MB completed
        entry.resume_offset = Some(536870912); // Resume from 512MB
        entry.status = "paused".to_string();

        let text = entry.serialize();

        // Verify resume offset is serialized correctly
        assert!(
            text.contains("RESUME_OFFSET=536870912"),
            "resume offset should be serialized correctly"
        );

        // Deserialize and verify
        let restored = SessionEntry::deserialize_line(&text).unwrap();
        assert_eq!(
            restored.resume_offset,
            Some(536870912),
            "resume offset should be restored correctly"
        );
        assert_eq!(restored.status, "paused");
    }

    #[test]
    fn test_bt_specific_fields_only_when_present() {
        // Test that BT-specific fields are truly optional
        let mut entry = SessionEntry::new(1, vec!["magnet:?xt=urn:btih:abc123".to_string()]);

        // Don't set any BT fields (keep them as None)
        let text_without_bt = entry.serialize();
        let restored_without_bt = SessionEntry::deserialize_line(&text_without_bt).unwrap();

        assert_eq!(restored_without_bt.bitfield, None);
        assert_eq!(restored_without_bt.num_pieces, None);
        assert_eq!(restored_without_bt.piece_length, None);
        assert_eq!(restored_without_bt.info_hash_hex, None);

        // Now set BT fields
        entry.bitfield = Some(vec![0xAA, 0xBB]);
        entry.num_pieces = Some(16);
        entry.piece_length = Some(524288);
        entry.info_hash_hex = Some("abc123def456".to_string());

        let text_with_bt = entry.serialize();
        let restored_with_bt = SessionEntry::deserialize_line(&text_with_bt).unwrap();

        assert_eq!(restored_with_bt.bitfield, Some(vec![0xAA, 0xBB]));
        assert_eq!(restored_with_bt.num_pieces, Some(16));
        assert_eq!(restored_with_bt.piece_length, Some(524288));
        assert_eq!(
            restored_with_bt.info_hash_hex,
            Some("abc123def456".to_string())
        );
    }

    #[test]
    fn test_download_options_to_map_all_fields() {
        // Verify that all non-default fields are serialized to the map
        let opts = DownloadOptions {
            split: Some(8),
            max_connection_per_server: Some(4),
            max_download_limit: Some(102400),
            max_upload_limit: Some(51200),
            dir: Some("/downloads".to_string()),
            out: Some("file.bin".to_string()),
            seed_time: Some(3600),
            seed_ratio: Some(2.0),
            // File allocation
            file_allocation: Some("trunc".to_string()),
            mmap_threshold: Some(128 * 1024 * 1024),
            secure_falloc: true,
            // Checksum
            checksum: Some(("sha256".to_string(), "abc123".to_string())),
            // Cookies
            cookie_file: Some("/tmp/cookies.txt".to_string()),
            cookies: Some("key=value".to_string()),
            // BT
            bt_force_encrypt: true,
            bt_require_crypto: true,
            enable_dht: false,
            dht_listen_port: Some(6881),
            dht_entry_point: Some(vec!["router.bittorrent.com:6881".to_string()]),
            enable_public_trackers: false,
            bt_piece_selection_strategy: "sequential".to_string(),
            bt_endgame_threshold: 10,
            bt_max_upload_slots: Some(4),
            bt_optimistic_unchoke_interval: Some(30),
            bt_snubbed_timeout: Some(60),
            bt_prioritize_piece: "head".to_string(),
            enable_utp: true,
            utp_listen_port: Some(6882),
            // Retry
            max_retries: 5,
            retry_wait: 3,
            // DHT file
            dht_file_path: Some("/tmp/dht.dat".to_string()),
            // Proxy
            http_proxy: Some("http://proxy:8080".to_string()),
            all_proxy: Some("socks5://proxy:1080".to_string()),
            https_proxy: Some("http://proxy:8443".to_string()),
            ftp_proxy: Some("http://proxy:8021".to_string()),
            no_proxy: Some("localhost,127.0.0.1".to_string()),
            // HTTP headers
            header: vec!["X-Custom: foo".to_string(), "X-Other: bar".to_string()],
            user_agent: Some("aria2-rust/1.0".to_string()),
            referer: Some("http://example.com".to_string()),
        };

        let map = download_options_to_map(&opts);

        // File allocation
        assert_eq!(map.get("file-allocation").unwrap(), "trunc");
        assert_eq!(map.get("mmap-threshold").unwrap(), "134217728");
        assert_eq!(map.get("secure-falloc").unwrap(), "true");

        // Checksum
        assert_eq!(map.get("checksum").unwrap(), "sha256=abc123");

        // Cookies
        assert_eq!(map.get("cookie-file").unwrap(), "/tmp/cookies.txt");
        assert_eq!(map.get("cookies").unwrap(), "key=value");

        // BT
        assert_eq!(map.get("bt-force-encrypt").unwrap(), "true");
        assert_eq!(map.get("bt-require-crypto").unwrap(), "true");
        assert_eq!(map.get("enable-dht").unwrap(), "false");
        assert_eq!(map.get("dht-listen-port").unwrap(), "6881");
        assert_eq!(
            map.get("dht-entry-point").unwrap(),
            "router.bittorrent.com:6881"
        );
        assert_eq!(map.get("enable-public-trackers").unwrap(), "false");
        assert_eq!(
            map.get("bt-piece-selection-strategy").unwrap(),
            "sequential"
        );
        assert_eq!(map.get("bt-endgame-threshold").unwrap(), "10");
        assert_eq!(map.get("bt-max-upload-slots").unwrap(), "4");
        assert_eq!(map.get("bt-optimistic-unchoke-interval").unwrap(), "30");
        assert_eq!(map.get("bt-snubbed-timeout").unwrap(), "60");
        assert_eq!(map.get("bt-prioritize-piece").unwrap(), "head");
        assert_eq!(map.get("enable-utp").unwrap(), "true");
        assert_eq!(map.get("utp-listen-port").unwrap(), "6882");

        // Retry
        assert_eq!(map.get("max-retries").unwrap(), "5");
        assert_eq!(map.get("retry-wait").unwrap(), "3");

        // DHT file
        assert_eq!(map.get("dht-file-path").unwrap(), "/tmp/dht.dat");

        // Proxy
        assert_eq!(map.get("http-proxy").unwrap(), "http://proxy:8080");
        assert_eq!(map.get("all-proxy").unwrap(), "socks5://proxy:1080");
        assert_eq!(map.get("https-proxy").unwrap(), "http://proxy:8443");
        assert_eq!(map.get("ftp-proxy").unwrap(), "http://proxy:8021");
        assert_eq!(map.get("no-proxy").unwrap(), "localhost,127.0.0.1");

        // HTTP headers
        assert_eq!(map.get("header").unwrap(), "X-Custom: foo,X-Other: bar");
        assert_eq!(map.get("user-agent").unwrap(), "aria2-rust/1.0");
        assert_eq!(map.get("referer").unwrap(), "http://example.com");
    }

    #[test]
    fn test_download_options_to_map_defaults_excluded() {
        // Default DownloadOptions should produce a minimal map.
        // enable_dht and enable_public_trackers default to true (matching the
        // load path's `unwrap_or(true)`), so they are NOT saved when at the
        // default value — the save logic only serializes them when disabled.
        let opts = DownloadOptions::default();
        let map = download_options_to_map(&opts);

        // secure_falloc defaults to false -> should NOT be in map
        assert!(!map.contains_key("secure-falloc"));
        // file_allocation defaults to None -> should NOT be in map
        assert!(!map.contains_key("file-allocation"));
        // enable_dht and enable_public_trackers default to true -> NOT saved
        assert!(!map.contains_key("enable-dht"));
        assert!(!map.contains_key("enable-public-trackers"));
    }
}