ebook-rs 0.13.0

use std::collections::HashMap;
use std::io::{Cursor, Read};
use zip::ZipArchive;

/// Represents an EPUB archive (ZIP container) in memory or from file.
#[derive(Clone)]
pub struct EpubArchive {
    files: HashMap<String, Vec<u8>>,
    files_lower: HashMap<String, String>,
}

impl EpubArchive {
    /// Open an `EpubArchive` from a filesystem path.
    pub fn open(path: &str) -> Result<Self, String> {
        let bytes =
            std::fs::read(path).map_err(|e| format!("Failed to read EPUB file {}: {}", path, e))?;
        Self::from_bytes(&bytes)
    }

    /// Create an empty `EpubArchive` instance.
    pub fn empty() -> Self {
        Self {
            files: HashMap::new(),
            files_lower: HashMap::new(),
        }
    }

    /// Insert or update a file entry in the archive.
    pub fn insert(&mut self, path: impl Into<String>, data: Vec<u8>) {
        let key = path.into();
        self.files_lower.insert(key.to_lowercase(), key.clone());
        self.files.insert(key, data);
    }

    /// Access reference to underlying files map in the archive.
    pub fn files(&self) -> &HashMap<String, Vec<u8>> {
        &self.files
    }

    /// Retrieve `.opf` package document path from `META-INF/container.xml`.
    pub fn get_opf_path(&self) -> Result<String, String> {
        let container_xml = self.read_string("META-INF/container.xml")?;
        crate::opf::parse_container_xml(&container_xml)
    }

    /// Helper to detect MIME type from entry file extension.
    pub fn get_mime_type(path: &str) -> &'static str {
        let lower = path.to_lowercase();
        if lower.ends_with(".xhtml") || lower.ends_with(".html") || lower.ends_with(".htm") {
            "application/xhtml+xml"
        } else if lower.ends_with(".css") {
            "text/css"
        } else if lower.ends_with(".jpg") || lower.ends_with(".jpeg") {
            "image/jpeg"
        } else if lower.ends_with(".png") {
            "image/png"
        } else if lower.ends_with(".gif") {
            "image/gif"
        } else if lower.ends_with(".svg") {
            "image/svg+xml"
        } else if lower.ends_with(".webp") {
            "image/webp"
        } else if lower.ends_with(".ttf")
            || lower.ends_with(".otf")
            || lower.ends_with(".woff")
            || lower.ends_with(".woff2")
        {
            "font/otf"
        } else if lower.ends_with(".ncx") {
            "application/x-dtbncx+xml"
        } else {
            "application/octet-stream"
        }
    }

    /// Create an `EpubArchive` from raw ZIP byte data with Zip Bomb protection.
    pub fn from_bytes(bytes: &[u8]) -> Result<Self, String> {
        let cursor = Cursor::new(bytes);
        let mut zip =
            ZipArchive::new(cursor).map_err(|e| format!("Failed to parse ZIP archive: {}", e))?;
        let mut files = HashMap::new();
        let mut files_lower = HashMap::new();
        let mut total_decompressed_bytes: u64 = 0;
        const MAX_TOTAL_SIZE: u64 = 500 * 1024 * 1024; // 500 MB max total size
        const MAX_ENTRY_SIZE: u64 = 200 * 1024 * 1024; // 200 MB max entry size

        for i in 0..zip.len() {
            let mut file = zip
                .by_index(i)
                .map_err(|e| format!("Failed to read file index {}: {}", i, e))?;
            let name = file.name().to_string();
            // Ignore directories
            if name.ends_with('/') {
                continue;
            }

            if file.size() > MAX_ENTRY_SIZE {
                return Err(format!(
                    "ZIP entry '{}' exceeds maximum allowed uncompressed size of 200MB",
                    name
                ));
            }

            let mut content = Vec::new();
            let mut chunk = [0u8; 8192];
            let mut entry_bytes_read: u64 = 0;

            loop {
                let n = file
                    .read(&mut chunk)
                    .map_err(|e| format!("Failed to read entry content {}: {}", name, e))?;
                if n == 0 {
                    break;
                }
                entry_bytes_read += n as u64;
                total_decompressed_bytes += n as u64;

                if entry_bytes_read > MAX_ENTRY_SIZE {
                    return Err(format!(
                        "ZIP entry '{}' decompressed size exceeded 200MB limit",
                        name
                    ));
                }
                if total_decompressed_bytes > MAX_TOTAL_SIZE {
                    return Err(
                        "ZIP archive total decompressed size exceeded 500MB safety limit"
                            .to_string(),
                    );
                }
                content.extend_from_slice(&chunk[..n]);
            }

            let normalized = normalize_path(&name);
            files_lower.insert(normalized.to_lowercase(), normalized.clone());
            files.insert(normalized, content);
        }

        Ok(Self { files, files_lower })
    }

    /// Read raw bytes of a file in the archive (cloning into a new Vec<u8>).
    pub fn read_bytes(&self, path: &str) -> Result<Vec<u8>, String> {
        self.read_bytes_ref(path).map(|bytes| bytes.to_vec())
    }

    /// Zero-copy reference getter for raw file bytes in the archive (P6 Fix).
    pub fn read_bytes_ref(&self, path: &str) -> Result<&[u8], String> {
        let clean = normalize_path(path);
        let clean_no_frag = clean.split('#').next().unwrap_or(&clean);
        if let Some(data) = self.files.get(clean_no_frag) {
            return Ok(data.as_slice());
        }
        let lower = clean_no_frag.to_lowercase();
        if let Some(orig_key) = self.files_lower.get(&lower) {
            if let Some(data) = self.files.get(orig_key) {
                return Ok(data.as_slice());
            }
        }
        Err(format!("File not found in archive: {}", path))
    }

    /// Read text content of a file in the archive with SIMD UTF-8 decoding.
    pub fn read_string(&self, path: &str) -> Result<String, String> {
        let bytes = self.read_bytes_ref(path)?;
        if let Ok(s) = simdutf8::basic::from_utf8(bytes) {
            Ok(s.to_string())
        } else {
            Ok(String::from_utf8_lossy(bytes).to_string())
        }
    }

    /// Check if a file exists in the archive (P5 Fix: O(1) lookup).
    pub fn contains(&self, path: &str) -> bool {
        let clean = normalize_path(path);
        let clean_no_frag = clean.split('#').next().unwrap_or(&clean);
        self.files.contains_key(clean_no_frag)
            || self.files_lower.contains_key(&clean_no_frag.to_lowercase())
    }

    /// List all unique file entry paths inside the archive.
    pub fn list_files(&self) -> Vec<String> {
        // P2 Fix: Iterate keys directly without double allocation into a HashSet
        let mut paths: Vec<String> = self.files.keys().cloned().collect();
        paths.sort();
        paths.dedup();
        paths
    }
}

/// Helper function to normalize ZIP entry paths.
pub fn normalize_path(path: &str) -> String {
    let clean = path.replace('\\', "/");
    let mut parts = Vec::new();
    for part in clean.split('/') {
        match part {
            "" | "." => {}
            ".." => {
                parts.pop();
            }
            _ => parts.push(part),
        }
    }
    parts.join("/")
}

/// Helper function to resolve relative paths against a base directory.
pub fn resolve_relative_path(base_dir: &str, relative: &str) -> String {
    // 1. Strip URL fragment identifier (#fragment)
    let rel_no_frag = relative.split('#').next().unwrap_or(relative);
    // 1b. Strip URL query string (?v=2, ?cache=...) — CSS versioned hrefs
    let rel_no_query = rel_no_frag.split('?').next().unwrap_or(rel_no_frag);
    // 2. Percent-decode URI path (%20, non-ASCII)
    let decoded = percent_encoding::percent_decode_str(rel_no_query)
        .decode_utf8_lossy()
        .to_string();

    let rel_clean = decoded.replace('\\', "/");
    if rel_clean.starts_with('/') {
        return normalize_path(&rel_clean);
    }
    let combined = if base_dir.is_empty() {
        rel_clean
    } else {
        format!("{}/{}", base_dir, rel_clean)
    };
    normalize_path(&combined)
}

/// Helper for HTTP Range request generation and byte-slice streaming (`bytes=start-end`).
#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub struct HttpRangeRequest {
    pub url: String,
    pub start: u64,
    pub end: Option<u64>,
}

impl HttpRangeRequest {
    /// Create a new HTTP Range byte slice request.
    pub fn new(url: &str, start: u64, end: Option<u64>) -> Self {
        Self {
            url: url.to_string(),
            start,
            end,
        }
    }

    /// Generate standard HTTP Range header tuple ("Range", "bytes=start-end").
    pub fn to_range_header(&self) -> (String, String) {
        let val = match self.end {
            Some(end_byte) => format!("bytes={}-{}", self.start, end_byte),
            None => format!("bytes={}-", self.start),
        };
        ("Range".to_string(), val)
    }

    /// Parse an incoming HTTP Range header string (e.g. "bytes=0-1024").
    pub fn parse_range_header(header_val: &str) -> Option<(u64, Option<u64>)> {
        let clean = header_val.trim();
        let spec = clean.strip_prefix("bytes=")?;
        let mut parts = spec.split('-');
        let start = parts.next()?.parse::<u64>().ok()?;
        let end = parts.next().and_then(|s| s.parse::<u64>().ok());
        Some((start, end))
    }
}

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

    #[test]
    fn test_normalize_and_resolve() {
        assert_eq!(
            normalize_path("OEBPS/../OEBPS/ch1.xhtml"),
            "OEBPS/ch1.xhtml"
        );
        assert_eq!(
            resolve_relative_path("OEBPS/Text", "../Images/cover.jpg"),
            "OEBPS/Images/cover.jpg"
        );
    }
}