parx-rs 0.1.0

/*
 * Copyright 2026 PARX Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use crate::error::{ParxError, Result};
use crate::format::{BundleHeader, Trailer, BUNDLE_HEADER_SIZE, BUNDLE_MAGIC, TRAILER_SIZE};
use crate::proto::{BundleEntry, ParxBundle};
use bytes::Bytes;
use prost::Message;
use std::collections::HashMap;
use std::time::{SystemTime, UNIX_EPOCH};

/// Default bundle filename.
pub const BUNDLE_FILENAME: &str = "_parx_bundle.parx";

/// Data for a single entry in the bundle.
#[derive(Debug, Clone)]
pub struct BundleEntryData {
    /// Relative path to the Parquet file.
    pub parquet_path: String,
    /// Source file size for staleness detection.
    pub source_size: u64,
    /// Raw footer bytes.
    pub footer_bytes: Bytes,
    /// Optional raw page index bytes.
    pub page_index_bytes: Bytes,
}

/// Writer for PARX bundle files.
///
/// Combines multiple Parquet file footers into a single bundle file.
#[derive(Debug)]
pub struct ParxBundleWriter {
    entries: Vec<BundleEntryData>,
}

impl ParxBundleWriter {
    /// Create a new bundle writer.
    pub const fn new() -> Self {
        Self {
            entries: Vec::new(),
        }
    }

    /// Add an entry to the bundle.
    pub fn add_entry(
        &mut self,
        parquet_path: &str,
        source_size: u64,
        footer_bytes: impl Into<Bytes>,
    ) {
        self.add_entry_with_page_indexes(parquet_path, source_size, footer_bytes, Bytes::new());
    }

    /// Add an entry to the bundle with optional page indexes.
    pub fn add_entry_with_page_indexes(
        &mut self,
        parquet_path: &str,
        source_size: u64,
        footer_bytes: impl Into<Bytes>,
        page_index_bytes: impl Into<Bytes>,
    ) {
        self.entries.push(BundleEntryData {
            parquet_path: parquet_path.to_string(),
            source_size,
            footer_bytes: footer_bytes.into(),
            page_index_bytes: page_index_bytes.into(),
        });
    }

    /// Get the number of entries in the bundle.
    #[inline]
    pub fn entry_count(&self) -> usize {
        self.entries.len()
    }

    /// Build the bundle file bytes
    ///
    /// # Panics
    /// Panics if manifest exceeds 4GB.
    pub fn finish(self) -> Vec<u8> {
        let header = BundleHeader::new(self.entries.len() as u64);
        let header_bytes = header.to_bytes();

        let mut current_offset = BUNDLE_HEADER_SIZE as u64;
        let mut payload = Vec::new();
        let mut bundle_entries = Vec::new();

        for entry in &self.entries {
            // Footer section
            let footer_offset = current_offset;
            let footer_length = entry.footer_bytes.len() as u64;
            let footer_checksum = crc32c::crc32c(&entry.footer_bytes).to_le_bytes().to_vec();

            payload.extend_from_slice(&entry.footer_bytes);
            current_offset += footer_length;

            // Optional page index section
            let (page_index_offset, page_index_length, page_index_checksum) =
                if entry.page_index_bytes.is_empty() {
                    (0, 0, Vec::new())
                } else {
                    let page_index_offset = current_offset;
                    let page_index_length = entry.page_index_bytes.len() as u64;
                    let page_index_checksum = crc32c::crc32c(&entry.page_index_bytes)
                        .to_le_bytes()
                        .to_vec();
                    payload.extend_from_slice(&entry.page_index_bytes);
                    current_offset += page_index_length;
                    (page_index_offset, page_index_length, page_index_checksum)
                };

            bundle_entries.push(BundleEntry {
                parquet_path: entry.parquet_path.clone(),
                source_size: entry.source_size,
                footer_offset,
                footer_length,
                footer_checksum,
                page_index_offset,
                page_index_length,
                page_index_checksum,
            });
        }

        // Get current timestamp (safe cast: won't overflow until year 2554)
        #[allow(clippy::cast_possible_truncation)]
        let created_at_ms = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .map(|d| d.as_millis() as u64)
            .unwrap_or(0);

        // Build bundle manifest
        let bundle = ParxBundle {
            version: 1,
            created_at_ms,
            entries: bundle_entries,
        };

        let manifest_bytes = bundle.encode_to_vec();
        let manifest_crc = crc32c::crc32c(&manifest_bytes);

        // Build trailer with bundle magic
        let manifest_len = u32::try_from(manifest_bytes.len()).expect("manifest too large (>4GB)");
        let trailer = Trailer::new(manifest_len, manifest_crc, BUNDLE_MAGIC);
        let trailer_bytes = trailer.to_bytes();

        // Assemble file
        let total_size =
            header_bytes.len() + payload.len() + manifest_bytes.len() + trailer_bytes.len();

        let mut output = Vec::with_capacity(total_size);
        output.extend_from_slice(&header_bytes);
        output.extend_from_slice(&payload);
        output.extend_from_slice(&manifest_bytes);
        output.extend_from_slice(&trailer_bytes);

        output
    }
}

impl Default for ParxBundleWriter {
    fn default() -> Self {
        Self::new()
    }
}

/// Reference to a single entry in a bundle.
#[derive(Debug, Clone)]
pub struct BundleEntryRef<'a> {
    /// Relative path to the Parquet file.
    pub parquet_path: &'a str,
    /// Source file size.
    pub source_size: u64,
    /// Footer bytes.
    pub footer_bytes: &'a [u8],
    /// Optional page index bytes.
    pub page_index_bytes: Option<&'a [u8]>,
}

/// Reader for PARX bundle files.
///
/// Provides access to all cached footers in the bundle.
#[derive(Debug, Clone)]
pub struct ParxBundleReader {
    header: BundleHeader,
    bundle: ParxBundle,
    data: Bytes,
    /// Index for fast path lookup.
    path_index: HashMap<String, usize>,
}

impl ParxBundleReader {
    /// Open a bundle from bytes.
    ///
    /// # Errors
    /// Returns error if file is invalid or corrupted.
    ///
    /// # Panics
    /// Panics if file size is less than minimum header size.
    pub fn open(data: Bytes) -> Result<Self> {
        let file_size = data.len();
        let min_size = BUNDLE_HEADER_SIZE + TRAILER_SIZE;

        if file_size < min_size {
            return Err(ParxError::FileTooSmall {
                size: file_size,
                minimum: min_size,
            });
        }

        // Parse header
        let header_bytes: [u8; BUNDLE_HEADER_SIZE] = data[..BUNDLE_HEADER_SIZE]
            .try_into()
            .expect("header slice length verified above");
        let header = BundleHeader::from_bytes(&header_bytes);

        // Validate header magic
        if !header.is_magic_valid() {
            return Err(ParxError::InvalidBundleMagic(header.magic));
        }

        // Validate version
        if !header.is_version_supported() {
            return Err(ParxError::UnsupportedVersion {
                major: header.version_major,
                minor: header.version_minor,
            });
        }

        // Parse trailer
        let trailer_bytes: [u8; TRAILER_SIZE] = data[file_size - TRAILER_SIZE..]
            .try_into()
            .expect("trailer slice length verified above");
        let trailer = Trailer::from_bytes(&trailer_bytes);

        // Validate trailer magic
        if !trailer.is_magic_valid(BUNDLE_MAGIC) {
            return Err(ParxError::InvalidBundleMagic(trailer.magic));
        }

        // Extract and validate manifest
        let manifest_end = file_size - TRAILER_SIZE;
        let manifest_start = manifest_end
            .checked_sub(trailer.manifest_len as usize)
            .ok_or(ParxError::FileTooSmall {
                size: file_size,
                minimum: min_size + trailer.manifest_len as usize,
            })?;

        let manifest_bytes = &data[manifest_start..manifest_end];

        // Verify manifest CRC
        let actual_crc = crc32c::crc32c(manifest_bytes);
        if actual_crc != trailer.manifest_crc32c {
            return Err(ParxError::ManifestChecksumMismatch {
                expected: trailer.manifest_crc32c,
                actual: actual_crc,
            });
        }

        // Decode bundle manifest
        let bundle = ParxBundle::decode(manifest_bytes)?;

        // Build path index
        let path_index: HashMap<String, usize> = bundle
            .entries
            .iter()
            .enumerate()
            .map(|(i, e)| (e.parquet_path.clone(), i))
            .collect();

        Ok(Self {
            header,
            bundle,
            data,
            path_index,
        })
    }

    /// Get the bundle header.
    #[inline]
    pub const fn header(&self) -> &BundleHeader {
        &self.header
    }

    /// Get the number of entries in the bundle.
    #[inline]
    pub fn entry_count(&self) -> usize {
        self.bundle.entries.len()
    }

    /// Get the creation timestamp in milliseconds.
    #[inline]
    pub const fn created_at_ms(&self) -> u64 {
        self.bundle.created_at_ms
    }

    /// Check if a parquet path exists in the bundle.
    #[inline]
    pub fn contains(&self, parquet_path: &str) -> bool {
        self.path_index.contains_key(parquet_path)
    }

    /// Get the list of parquet paths in this bundle.
    pub fn parquet_paths(&self) -> Vec<&str> {
        self.bundle
            .entries
            .iter()
            .map(|e| e.parquet_path.as_str())
            .collect()
    }

    /// Get footer bytes for a specific parquet file.
    pub fn get_footer(&self, parquet_path: &str) -> Option<&[u8]> {
        let idx = *self.path_index.get(parquet_path)?;
        let entry = &self.bundle.entries[idx];

        let start = usize::try_from(entry.footer_offset).ok()?;
        let length = usize::try_from(entry.footer_length).ok()?;
        let end = start
            .checked_add(length)
            .filter(|&end| end <= self.data.len())?;

        Some(&self.data[start..end])
    }

    /// Get source size for a specific parquet file.
    pub fn get_source_size(&self, parquet_path: &str) -> Option<u64> {
        let idx = *self.path_index.get(parquet_path)?;
        Some(self.bundle.entries[idx].source_size)
    }

    /// Validate that a parquet file matches the expected size.
    pub fn validate_source_size(&self, parquet_path: &str, actual_size: u64) -> bool {
        self.get_source_size(parquet_path)
            .is_some_and(|expected| expected == actual_size)
    }

    /// Get a full entry reference for a parquet file.
    pub fn get_entry(&self, parquet_path: &str) -> Option<BundleEntryRef<'_>> {
        let idx = *self.path_index.get(parquet_path)?;
        let entry = &self.bundle.entries[idx];

        let footer_start = usize::try_from(entry.footer_offset).ok()?;
        let footer_length = usize::try_from(entry.footer_length).ok()?;
        let footer_end = footer_start
            .checked_add(footer_length)
            .filter(|&end| end <= self.data.len())?;

        let footer_bytes = &self.data[footer_start..footer_end];
        let page_index_bytes = self.resolve_page_index_bytes(entry)?;

        Some(BundleEntryRef {
            parquet_path: &entry.parquet_path,
            source_size: entry.source_size,
            footer_bytes,
            page_index_bytes,
        })
    }

    /// Iterate over all entries in the bundle.
    pub fn iter_entries(&self) -> impl Iterator<Item = BundleEntryRef<'_>> {
        self.bundle.entries.iter().filter_map(|entry| {
            let footer_start = usize::try_from(entry.footer_offset).ok()?;
            let footer_length = usize::try_from(entry.footer_length).ok()?;
            let footer_end = footer_start
                .checked_add(footer_length)
                .filter(|&end| end <= self.data.len())?;

            let footer_bytes = &self.data[footer_start..footer_end];
            let page_index_bytes = self.resolve_page_index_bytes(entry)?;

            Some(BundleEntryRef {
                parquet_path: &entry.parquet_path,
                source_size: entry.source_size,
                footer_bytes,
                page_index_bytes,
            })
        })
    }

    fn resolve_page_index_bytes<'a>(&'a self, entry: &BundleEntry) -> Option<Option<&'a [u8]>> {
        if entry.page_index_length == 0 {
            return Some(None);
        }

        let start = usize::try_from(entry.page_index_offset).ok()?;
        let length = usize::try_from(entry.page_index_length).ok()?;
        let end = start
            .checked_add(length)
            .filter(|&end| end <= self.data.len())?;
        Some(Some(&self.data[start..end]))
    }

    /// Validate all entry checksums.
    ///
    /// # Errors
    /// Returns error if any checksum fails or bounds are invalid.
    pub fn validate_all(&self) -> Result<()> {
        for entry in &self.bundle.entries {
            // Validate footer checksum
            let footer_start = usize::try_from(entry.footer_offset).map_err(|_| {
                ParxError::InvalidPayloadBounds {
                    offset: entry.footer_offset,
                    length: entry.footer_length,
                    file_size: self.data.len() as u64,
                }
            })?;
            let footer_length = usize::try_from(entry.footer_length).map_err(|_| {
                ParxError::InvalidPayloadBounds {
                    offset: entry.footer_offset,
                    length: entry.footer_length,
                    file_size: self.data.len() as u64,
                }
            })?;
            let footer_end = footer_start.checked_add(footer_length).ok_or_else(|| {
                ParxError::InvalidPayloadBounds {
                    offset: entry.footer_offset,
                    length: entry.footer_length,
                    file_size: self.data.len() as u64,
                }
            })?;

            if footer_end > self.data.len() {
                return Err(ParxError::InvalidPayloadBounds {
                    offset: entry.footer_offset,
                    length: entry.footer_length,
                    file_size: self.data.len() as u64,
                });
            }

            let footer_bytes = &self.data[footer_start..footer_end];
            let footer_crc = crc32c::crc32c(footer_bytes);

            if footer_crc.to_le_bytes().as_slice() != entry.footer_checksum.as_slice() {
                return Err(ParxError::FooterChecksumMismatch);
            }

            // Validate optional page index checksum
            if entry.page_index_length > 0 {
                let page_index_start = usize::try_from(entry.page_index_offset).map_err(|_| {
                    ParxError::InvalidPayloadBounds {
                        offset: entry.page_index_offset,
                        length: entry.page_index_length,
                        file_size: self.data.len() as u64,
                    }
                })?;
                let page_index_length = usize::try_from(entry.page_index_length).map_err(|_| {
                    ParxError::InvalidPayloadBounds {
                        offset: entry.page_index_offset,
                        length: entry.page_index_length,
                        file_size: self.data.len() as u64,
                    }
                })?;
                let page_index_end =
                    page_index_start
                        .checked_add(page_index_length)
                        .ok_or_else(|| ParxError::InvalidPayloadBounds {
                            offset: entry.page_index_offset,
                            length: entry.page_index_length,
                            file_size: self.data.len() as u64,
                        })?;

                if page_index_end > self.data.len() {
                    return Err(ParxError::InvalidPayloadBounds {
                        offset: entry.page_index_offset,
                        length: entry.page_index_length,
                        file_size: self.data.len() as u64,
                    });
                }

                let page_index_bytes = &self.data[page_index_start..page_index_end];
                let page_index_crc = crc32c::crc32c(page_index_bytes);
                if page_index_crc.to_le_bytes().as_slice() != entry.page_index_checksum.as_slice() {
                    return Err(ParxError::PageIndexChecksumMismatch);
                }
            }
        }

        Ok(())
    }
}

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

    #[test]
    fn test_bundle_roundtrip() {
        let mut writer = ParxBundleWriter::new();
        writer.add_entry("part-00000.parquet", 1000, b"footer0".to_vec());
        writer.add_entry("part-00001.parquet", 2000, b"footer1".to_vec());
        writer.add_entry("part-00002.parquet", 3000, b"footer2".to_vec());

        let bundle_bytes = writer.finish();
        let reader = ParxBundleReader::open(Bytes::from(bundle_bytes)).expect("failed to open");

        assert_eq!(reader.entry_count(), 3);
        assert!(reader.contains("part-00000.parquet"));
        assert!(reader.contains("part-00001.parquet"));
        assert!(reader.contains("part-00002.parquet"));
        assert!(!reader.contains("nonexistent.parquet"));

        assert_eq!(
            reader.get_footer("part-00000.parquet"),
            Some(b"footer0".as_slice())
        );
        assert_eq!(
            reader.get_footer("part-00001.parquet"),
            Some(b"footer1".as_slice())
        );
        assert_eq!(
            reader.get_footer("part-00002.parquet"),
            Some(b"footer2".as_slice())
        );

        assert_eq!(reader.get_source_size("part-00000.parquet"), Some(1000));
        assert_eq!(reader.get_source_size("part-00001.parquet"), Some(2000));

        assert!(reader.validate_source_size("part-00000.parquet", 1000));
        assert!(!reader.validate_source_size("part-00000.parquet", 9999));
    }

    #[test]
    fn test_bundle_iter_entries() {
        let mut writer = ParxBundleWriter::new();
        writer.add_entry("a.parquet", 100, b"fa".to_vec());
        writer.add_entry("b.parquet", 200, b"fb".to_vec());

        let bundle_bytes = writer.finish();
        let reader = ParxBundleReader::open(Bytes::from(bundle_bytes)).expect("failed to open");

        let entries: Vec<_> = reader.iter_entries().collect();
        assert_eq!(entries.len(), 2);
        assert_eq!(entries[0].parquet_path, "a.parquet");
        assert_eq!(entries[0].footer_bytes, b"fa");
        assert!(entries[0].page_index_bytes.is_none());
        assert_eq!(entries[1].parquet_path, "b.parquet");
        assert_eq!(entries[1].footer_bytes, b"fb");
        assert!(entries[1].page_index_bytes.is_none());
    }

    #[test]
    fn test_bundle_validate_all() {
        let mut writer = ParxBundleWriter::new();
        writer.add_entry("test.parquet", 1000, b"footer".to_vec());

        let bundle_bytes = writer.finish();
        let reader = ParxBundleReader::open(Bytes::from(bundle_bytes)).expect("failed to open");

        // Should pass validation
        reader.validate_all().expect("validation should pass");
    }

    #[test]
    fn test_bundle_parquet_paths() {
        let mut writer = ParxBundleWriter::new();
        writer.add_entry("z.parquet", 100, b"f".to_vec());
        writer.add_entry("a.parquet", 200, b"f".to_vec());
        writer.add_entry("m.parquet", 300, b"f".to_vec());

        let bundle_bytes = writer.finish();
        let reader = ParxBundleReader::open(Bytes::from(bundle_bytes)).expect("failed to open");

        let paths = reader.parquet_paths();
        assert_eq!(paths, vec!["z.parquet", "a.parquet", "m.parquet"]);
    }

    #[test]
    fn test_invalid_bundle_magic() {
        let mut data = vec![0u8; 100];
        data[0..4].copy_from_slice(b"NOPE");

        let result = ParxBundleReader::open(Bytes::from(data));
        assert!(matches!(result, Err(ParxError::InvalidBundleMagic(_))));
    }

    #[test]
    fn test_bundle_manifest_crc_mismatch() {
        let mut writer = ParxBundleWriter::new();
        writer.add_entry("test.parquet", 1000, b"footer".to_vec());

        let mut bundle_bytes = writer.finish();
        // Corrupt manifest CRC (bytes -8 to -5 from end)
        let len = bundle_bytes.len();
        bundle_bytes[len - 8] ^= 0xFF;

        let result = ParxBundleReader::open(Bytes::from(bundle_bytes));
        assert!(matches!(
            result,
            Err(ParxError::ManifestChecksumMismatch { .. })
        ));
    }

    #[test]
    fn test_bundle_reader_handles_normal_case() {
        // Create a simple valid bundle as baseline
        let mut writer = ParxBundleWriter::new();

        // Add a normal entry
        let footer = vec![1, 2, 3, 4];
        writer.add_entry("test.parquet", 1000, footer.clone());

        let bundle_bytes = writer.finish();

        // Should open and read successfully
        let reader = ParxBundleReader::open(bundle_bytes.into()).expect("Should open valid bundle");
        let retrieved = reader
            .get_footer("test.parquet")
            .expect("Should find footer");
        assert_eq!(retrieved, &footer[..]);
    }

    #[test]
    fn test_bundle_with_page_indexes_roundtrip() {
        let mut writer = ParxBundleWriter::new();
        writer.add_entry_with_page_indexes(
            "test.parquet",
            1000,
            b"footer".to_vec(),
            b"pi".to_vec(),
        );

        let bundle_bytes = writer.finish();
        let reader = ParxBundleReader::open(bundle_bytes.into()).expect("Should open valid bundle");
        let entry = reader
            .get_entry("test.parquet")
            .expect("Should find bundle entry");

        assert_eq!(entry.footer_bytes, b"footer");
        assert_eq!(entry.page_index_bytes, Some(b"pi".as_slice()));
        reader.validate_all().expect("validation should pass");
    }
}