v2rmp 0.3.5

rmpca — Route Optimization TUI
Documentation 
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use anyhow::Context;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::io::Read;
use std::time::Instant;

use super::clean::{clean_geojson, CleanOptions, CleanStats};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CompileRequest {
    pub input_geojson: String,
    pub output_rmp: String,
    pub compress: bool,
    pub road_classes: Vec<String>,
    pub clean_options: Option<CleanOptions>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CompileResult {
    pub input_size_bytes: u64,
    pub output_size_bytes: u64,
    pub node_count: usize,
    pub edge_count: usize,
    pub elapsed_ms: u64,
}

/// .rmp binary format header (magic + version).
const RMP_MAGIC: &[u8; 4] = b"RMP1";

/// Compile a GeoJSON road network into the .rmp binary format.
///
/// Binary layout:
///   [4]  magic "RMP1"
///   [4]  node count (u32 LE)
///   [4]  edge count (u32 LE)
///   [N]  node entries: lat(f64) lon(f64) = 16 bytes each
///   [E]  edge entries: from(u32 LE) to(u32 LE) weight_m(f64 LE) oneway(u8) = 17 bytes each
///   [4]  CRC32 checksum (LE)
pub fn run_compile(req: &CompileRequest) -> anyhow::Result<CompileResult> {
    let start = Instant::now();

    // 1. Read the GeoJSON file
    let mut input_data = Vec::new();
    {
        let mut file = std::fs::File::open(&req.input_geojson)
            .with_context(|| format!("Failed to open input GeoJSON: {}", req.input_geojson))?;
        file.read_to_end(&mut input_data)?;
    }
    let input_size_bytes = input_data.len() as u64;

    // 2. Parse into FeatureCollection
    let mut geojson: geojson::FeatureCollection = serde_json::from_slice(&input_data)
        .with_context(|| "Failed to parse GeoJSON FeatureCollection")?;

    // 2.5. Clean GeoJSON if options provided
    let mut _clean_stats: Option<CleanStats> = None;
    if let Some(ref clean_opts) = req.clean_options {
        let (cleaned_fc, stats, _warnings) = clean_geojson(&geojson, clean_opts)
            .with_context(|| "Failed to clean GeoJSON")?;
        _clean_stats = Some(stats);
        geojson = cleaned_fc;
    }

    // 3. Deduplicate nodes by snapping coordinates to 1e6 precision
    //    and 4. Build adjacency list of edges
    let mut node_map: HashMap<(i64, i64), u32> = HashMap::new();
    let mut nodes: Vec<(f64, f64)> = Vec::new(); // (lat, lon) in original precision
    let mut edges: Vec<(u32, u32, f64, u8)> = Vec::new(); // (from, to, weight_m, oneway)

    for feature in &geojson.features {
        let geometry = match feature.geometry.as_ref() {
            Some(g) => g,
            None => continue,
        };

        // Determine oneway from properties
        let oneway = feature
            .properties
            .as_ref()
            .and_then(|props| props.get("oneway"))
            .and_then(|v| v.as_str())
            .map(|s| {
                if matches!(s, "yes" | "1" | "true") { 1u8 } else { 0u8 }
            })
            .unwrap_or(0);

        let line_strings: Vec<&Vec<Vec<f64>>> = match &geometry.value {
            geojson::Value::LineString(coords) => vec![coords],
            geojson::Value::MultiLineString(multi) => multi.iter().collect(),
            _ => continue,
        };

        for coords in line_strings {
            if coords.len() < 2 {
                continue;
            }

            let coord_points: Vec<(f64, f64)> = coords
                .iter()
                .filter(|p| p.len() >= 2)
                .map(|p| (p[1], p[0])) // (lat, lon)
                .collect();

            if coord_points.len() < 2 {
                continue;
            }

            for window in coord_points.windows(2) {
                let (lat1, lon1) = window[0];
                let (lat2, lon2) = window[1];

                let weight_m = haversine_distance_m(lat1, lon1, lat2, lon2);

                let from_node = get_or_create_node(&mut node_map, &mut nodes, lat1, lon1);
                let to_node = get_or_create_node(&mut node_map, &mut nodes, lat2, lon2);

                edges.push((from_node, to_node, weight_m, oneway));
            }
        }
    }

    let node_count = nodes.len();
    let edge_count = edges.len();

    // 5. Write the binary .rmp format
    let mut buf: Vec<u8> = Vec::new();

    // Magic
    buf.extend_from_slice(RMP_MAGIC);

    // Node count
    buf.extend_from_slice(&(node_count as u32).to_le_bytes());

    // Edge count
    buf.extend_from_slice(&(edge_count as u32).to_le_bytes());

    // Node entries: lat(f64 LE) lon(f64 LE) = 16 bytes each
    for (lat, lon) in &nodes {
        buf.extend_from_slice(&lat.to_le_bytes());
        buf.extend_from_slice(&lon.to_le_bytes());
    }

    // Edge entries: from(u32 LE) to(u32 LE) weight_m(f64 LE) oneway(u8) = 17 bytes each
    for (from, to, weight_m, oneway) in &edges {
        buf.extend_from_slice(&from.to_le_bytes());
        buf.extend_from_slice(&to.to_le_bytes());
        buf.extend_from_slice(&weight_m.to_le_bytes());
        buf.push(*oneway);
    }

    // CRC32 checksum (LE)
    let crc = crc32fast::hash(&buf);
    buf.extend_from_slice(&crc.to_le_bytes());

    // Write output file
    std::fs::write(&req.output_rmp, &buf)
        .with_context(|| format!("Failed to write output file: {}", req.output_rmp))?;

    let output_size_bytes = buf.len() as u64;
    let elapsed_ms = start.elapsed().as_millis() as u64;

    Ok(CompileResult {
        input_size_bytes,
        output_size_bytes,
        node_count,
        edge_count,
        elapsed_ms,
    })
}

/// Quick validation: check if a file starts with the RMP magic bytes.
pub fn is_rmp_file(data: &[u8]) -> bool {
    data.len() >= 4 && &data[..4] == RMP_MAGIC
}

/// Get or create a node ID for the given (lat, lon) coordinates.
/// Snaps to 1e6 precision for deduplication, but stores original-precision coords.
fn get_or_create_node(
    node_map: &mut HashMap<(i64, i64), u32>,
    nodes: &mut Vec<(f64, f64)>,
    lat: f64,
    lon: f64,
) -> u32 {
    let key = ((lat * 1e6) as i64, (lon * 1e6) as i64);
    *node_map.entry(key).or_insert_with(|| {
        let id = nodes.len() as u32;
        nodes.push((lat, lon));
        id
    })
}

/// Calculate haversine distance in meters between two (lat, lon) points.
fn haversine_distance_m(lat1: f64, lon1: f64, lat2: f64, lon2: f64) -> f64 {
    const EARTH_RADIUS_M: f64 = 6_371_000.0;

    let lat1_rad = lat1.to_radians();
    let lat2_rad = lat2.to_radians();
    let delta_lat = (lat2 - lat1).to_radians();
    let delta_lon = (lon2 - lon1).to_radians();

    let a = (delta_lat / 2.0).sin().powi(2)
        + lat1_rad.cos() * lat2_rad.cos() * (delta_lon / 2.0).sin().powi(2);
    let c = 2.0 * a.sqrt().atan2((1.0 - a).sqrt());

    EARTH_RADIUS_M * c
}