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//! Extracts all cities from a large .osm file.
//!
//! 1) Reads a large .osm file
//! 2) Finds all boundary relations representing cities
//! 3) Calculates the polygon covering that city
//! 4) Uses osmconvert to clip the large .osm to a smaller one with just the city
//!
//! This tool writes all output files (.poly boundaries and .osm extracts) in the current
//! directory!

use abstutil::{CmdArgs, Timer};
use geom::{Circle, Distance, GPSBounds, LonLat, Polygon};
use map_model::osm::OsmID;
use std::process::Command;

fn main() {
    let mut args = CmdArgs::new();
    let input = args.required_free();
    let radius_around_label: Option<Distance> = args
        .optional_parse("--radius_around_label_miles", |s| {
            s.parse::<f64>().map(|x| Distance::miles(x))
        });
    args.done();
    let mut timer = Timer::new(format!("extract cities from {}", input));

    // Infer the boundary of the input from the <bounds> tag
    let doc = convert_osm::reader::read(&input, &GPSBounds::new(), &mut timer).unwrap();
    for (id, rel) in &doc.relations {
        if !rel.tags.is("border_type", "city") && !rel.tags.is("place", "city") {
            continue;
        }
        let name = if let Some(name) = rel.tags.get("name:en").or(rel.tags.get("name")) {
            name
        } else {
            println!("{} has no name?", id);
            continue;
        };

        println!("Found city relation for {}: {}", name, id);

        let clip = if let Some(radius) = radius_around_label {
            // Just draw a circle around the relation's admin_centre or label
            let mut center = None;
            for (role, id) in &rel.members {
                if role == "admin_centre" || role == "label" {
                    if let OsmID::Node(n) = id {
                        center = Some(doc.nodes[n].pt);
                        break;
                    }
                }
            }
            if let Some(pt) = center {
                Circle::new(pt, radius).to_polygon()
            } else {
                println!("... but it has no admin_centre or label member");
                continue;
            }
        } else {
            // Glue together the outer members of the relation
            let polygons = convert_osm::osm_geom::glue_multipolygon(
                *id,
                convert_osm::osm_geom::get_multipolygon_members(*id, rel, &doc),
                None,
            );
            // Simplify the result (which often has thousands of points)
            println!(
                "Extracted {} from {}, using the convex hull of {} polygons",
                name,
                id,
                polygons.len(),
            );
            Polygon::convex_hull(polygons)
        };

        let clipping_polygon = format!("{}.poly", name);
        LonLat::write_osmosis_polygon(
            &clipping_polygon,
            &doc.gps_bounds.convert_back(clip.points()),
        )
        .unwrap();

        abstutil::must_run_cmd(
            Command::new("osmconvert")
                .arg(&input)
                .arg(format!("-B={}", clipping_polygon))
                .arg("--complete-ways")
                .arg(format!("-o={}.osm", name)),
        );
    }
}