libfreemkv 0.3.0

//! CLPI clip info parser — maps clips to sector ranges on disc.
//!
//! Each .clpi file in BDMV/CLIPINF/ describes one M2TS clip.
//! The EP (Entry Point) map provides timestamp → SPN mapping.
//! SPN × 192 = byte offset in the m2ts file.
//!
//! Reference: https://github.com/lw/BluRay/wiki/CLPI

use crate::error::{Error, Result};
use crate::disc::Extent;

/// Parsed CLPI clip info.
#[derive(Debug)]
pub struct ClipInfo {
    pub version: String,
    /// Total source packets in the m2ts (each 192 bytes)
    pub source_packet_count: u32,
    /// Coarse EP entries for the primary video stream
    pub ep_coarse: Vec<EpCoarse>,
    /// Fine EP entries for the primary video stream
    pub ep_fine: Vec<EpFine>,
}

#[derive(Debug, Clone)]
pub struct EpCoarse {
    pub ref_to_fine_id: u32,
    pub pts_coarse: u32,
    pub spn_coarse: u32,
}

#[derive(Debug, Clone)]
pub struct EpFine {
    pub pts_fine: u32,
    pub spn_fine: u32,
}

impl ClipInfo {
    /// Reconstruct full PTS from coarse + fine entry.
    pub fn full_pts(coarse: &EpCoarse, fine: &EpFine) -> u32 {
        (coarse.pts_coarse << 19) + (fine.pts_fine << 8)
    }

    /// Reconstruct full SPN from coarse + fine entry.
    pub fn full_spn(coarse: &EpCoarse, fine: &EpFine) -> u32 {
        (coarse.spn_coarse & 0xFFFE0000) + fine.spn_fine
    }

    /// Get all EP entries as (PTS, SPN) pairs, fully resolved.
    pub fn resolved_ep_map(&self) -> Vec<(u32, u32)> {
        let mut entries = Vec::new();

        for (ci, coarse) in self.ep_coarse.iter().enumerate() {
            let fine_start = coarse.ref_to_fine_id as usize;
            let fine_end = if ci + 1 < self.ep_coarse.len() {
                self.ep_coarse[ci + 1].ref_to_fine_id as usize
            } else {
                self.ep_fine.len()
            };

            for fi in fine_start..fine_end.min(self.ep_fine.len()) {
                let fine = &self.ep_fine[fi];
                let pts = Self::full_pts(coarse, fine);
                let spn = Self::full_spn(coarse, fine);
                entries.push((pts, spn));
            }
        }

        entries
    }

    /// Get sector extents for a given in/out time range.
    ///
    /// Converts PTS timestamps to SPN ranges, then SPN to LBA
    /// using the file's starting LBA on disc.
    pub fn get_extents(&self, in_time: u32, out_time: u32) -> Vec<Extent> {
        let ep_map = self.resolved_ep_map();
        if ep_map.is_empty() {
            return Vec::new();
        }

        // Find SPN at or before in_time
        let start_spn = match ep_map.binary_search_by_key(&in_time, |(pts, _)| *pts) {
            Ok(i) => ep_map[i].1,
            Err(0) => ep_map[0].1,
            Err(i) => ep_map[i - 1].1,
        };

        // Find SPN at or after out_time
        let end_spn = match ep_map.binary_search_by_key(&out_time, |(pts, _)| *pts) {
            Ok(i) => ep_map[i].1,
            Err(i) if i < ep_map.len() => ep_map[i].1,
            _ => ep_map.last().unwrap().1 + 1,
        };

        if end_spn <= start_spn {
            return Vec::new();
        }

        // SPN → byte offset: spn × 192
        // Byte offset → sectors: offset / 2048
        // Note: the caller needs to add the file's starting LBA from UDF
        let start_byte = start_spn as u64 * 192;
        let end_byte = end_spn as u64 * 192;
        let start_sector = (start_byte / 2048) as u32;
        let end_sector = ((end_byte + 2047) / 2048) as u32;

        vec![Extent {
            start_lba: start_sector, // relative to m2ts file start
            sector_count: end_sector - start_sector,
        }]
    }
}

/// Parse a CLPI file from raw bytes.
pub fn parse(data: &[u8]) -> Result<ClipInfo> {
    if data.len() < 40 {
        return Err(Error::DiscError { detail: "CLPI too short".into() });
    }

    if &data[0..4] != b"HDMV" {
        return Err(Error::DiscError { detail: "not a CLPI file".into() });
    }
    let version = String::from_utf8_lossy(&data[4..8]).to_string();

    // Header offsets
    let _seq_info_start = u32::from_be_bytes([data[8], data[9], data[10], data[11]]) as usize;
    let _prog_info_start = u32::from_be_bytes([data[12], data[13], data[14], data[15]]) as usize;
    let cpi_start = u32::from_be_bytes([data[16], data[17], data[18], data[19]]) as usize;

    // ClipInfo section at offset 40
    // source_packet_count at offset 40 + 4(len) + 2(reserved) + 1(stream_type) + 1(app_type) + 4(reserved) + 4(ts_rate)
    let source_packet_count = if data.len() > 56 {
        u32::from_be_bytes([data[56], data[57], data[58], data[59]])
    } else {
        0
    };

    // Parse CPI / EP Map
    let (ep_coarse, ep_fine) = if cpi_start > 0 && cpi_start + 8 < data.len() {
        parse_cpi(&data[cpi_start..])?
    } else {
        (Vec::new(), Vec::new())
    };

    Ok(ClipInfo {
        version,
        source_packet_count,
        ep_coarse,
        ep_fine,
    })
}

/// Parse the CPI section containing the EP map.
fn parse_cpi(data: &[u8]) -> Result<(Vec<EpCoarse>, Vec<EpFine>)> {
    if data.len() < 8 {
        return Ok((Vec::new(), Vec::new()));
    }

    let cpi_length = u32::from_be_bytes([data[0], data[1], data[2], data[3]]) as usize;
    if cpi_length < 4 {
        return Ok((Vec::new(), Vec::new()));
    }

    // CPI type at bits 44-47 (byte 5, lower 4 bits)
    // Skip to EP map: offset 4 (after length) + 2 (reserved/type)
    let ep_map = &data[6..];
    if ep_map.len() < 4 {
        return Ok((Vec::new(), Vec::new()));
    }

    // EP map header
    // [0] reserved
    // [1] number of stream PID entries
    let num_streams = ep_map[1] as usize;
    if num_streams == 0 {
        return Ok((Vec::new(), Vec::new()));
    }

    // Stream PID entry headers start at offset 2
    // Each: 2(PID) + 2(reserved+type) + 2(num_coarse) + 4(num_fine) + 4(ep_map_start) = 14 bytes
    // We only care about the first stream (primary video)
    if ep_map.len() < 16 {
        return Ok((Vec::new(), Vec::new()));
    }

    let _stream_pid = u16::from_be_bytes([ep_map[2], ep_map[3]]);
    // ep_map[4..6] = reserved + EP stream type
    let num_coarse = u16::from_be_bytes([ep_map[6], ep_map[7]]) as usize;
    let num_fine = u32::from_be_bytes([ep_map[8], ep_map[9], ep_map[10], ep_map[11]]) as usize;
    let ep_map_offset = u32::from_be_bytes([ep_map[12], ep_map[13], ep_map[14], ep_map[15]]) as usize;

    // EP map for this stream starts at ep_map_offset relative to ep_map start
    if ep_map_offset + 4 > ep_map.len() {
        return Ok((Vec::new(), Vec::new()));
    }

    let stream_ep = &ep_map[ep_map_offset..];
    if stream_ep.len() < 4 {
        return Ok((Vec::new(), Vec::new()));
    }

    // Fine table start address (relative to this stream EP map)
    let fine_start = u32::from_be_bytes([stream_ep[0], stream_ep[1], stream_ep[2], stream_ep[3]]) as usize;

    // Coarse entries start at offset 4, 8 bytes each
    let coarse_data = &stream_ep[4..];
    let mut ep_coarse = Vec::with_capacity(num_coarse);
    for i in 0..num_coarse {
        let off = i * 8;
        if off + 8 > coarse_data.len() {
            break;
        }

        let dword0 = u32::from_be_bytes([coarse_data[off], coarse_data[off + 1],
                                          coarse_data[off + 2], coarse_data[off + 3]]);
        let ref_to_fine_id = dword0 >> 14;
        let pts_coarse = dword0 & 0x3FFF;
        let spn_coarse = u32::from_be_bytes([coarse_data[off + 4], coarse_data[off + 5],
                                              coarse_data[off + 6], coarse_data[off + 7]]);

        ep_coarse.push(EpCoarse {
            ref_to_fine_id,
            pts_coarse,
            spn_coarse,
        });
    }

    // Fine entries at fine_start, 4 bytes each
    let mut ep_fine = Vec::with_capacity(num_fine);
    if fine_start < stream_ep.len() {
        let fine_data = &stream_ep[fine_start..];
        for i in 0..num_fine {
            let off = i * 4;
            if off + 4 > fine_data.len() {
                break;
            }

            let dword = u32::from_be_bytes([fine_data[off], fine_data[off + 1],
                                            fine_data[off + 2], fine_data[off + 3]]);
            // Bits: is_angle(1) + i_end_offset(3) + pts_fine(11) + spn_fine(17)
            let pts_fine = (dword >> 17) & 0x7FF;
            let spn_fine = dword & 0x1FFFF;

            ep_fine.push(EpFine { pts_fine, spn_fine });
        }
    }

    Ok((ep_coarse, ep_fine))
}