use std::collections::HashMap;
use std::io::BufReader;
use std::fs::File;
use std::sync::Arc;

use geo::prelude::{Area, Contains};


type Polygon = geo::Polygon<f64>;

struct Location {
    name: Arc<String>,
    poly: Arc<Polygon>,
    area: f64,
}

impl Location {
    pub fn new(name: &str, poly: Arc<Polygon>) -> Self {
        let area = poly.unsigned_area();
        Location {
            name: Arc::new(name.to_owned()),
            poly,
            area,
        }
    }

    pub fn contains(&self, coord: &geo::Coordinate<f64>) -> bool {
        self.poly.contains(coord)
    }
}

pub struct Locations {
    locations: Vec<Location>,
}

impl Locations {
    pub fn load(file: &str) -> Self {
        println!("Loading {}...", file);
        let json: serde_json::Value = serde_json::from_reader(BufReader::new(File::open(file).unwrap()))
            .unwrap();
        println!("parsed JSON");
        let obj = json.as_object().expect("json obj");
        let els = obj.get("elements").and_then(|v| v.as_array()).expect("els");
        println!("{} elements", els.len());

        let mut nodes = HashMap::new();
        for el in els {
            let el = el.as_object().expect("el");

            match el.get("type").and_then(|v| v.as_str()) {
                Some("node") => {
                    let id = el.get("id").and_then(|v| v.as_u64()).expect("id");
                    let lon = el.get("lon").expect("lon")
                        .as_f64().expect("lon f64");
                    let lat = el.get("lat").expect("lat")
                        .as_f64().expect("lat f64");
                    let coord = geo::Coordinate { x: lon, y: lat };
                    nodes.insert(id, coord);
                }
                _ => {}
            }
        }
        println!("{} nodes", nodes.len());

        let mut locations = vec![];
        let mut ways = HashMap::new();
        for el in els {
            let el = el.as_object().expect("el");

            match el.get("type").and_then(|v| v.as_str()) {
                Some("way") => {
                    let id = el.get("id").and_then(|v| v.as_u64()).expect("id");
                    let way_nodes = el.get("nodes").and_then(|v| v.as_array()).expect("nodes")
                        .iter()
                        .map(|way_node| way_node.as_u64().expect("way_node"))
                        .collect::<Vec<_>>();
                    ways.insert(id, way_nodes.clone());

                    if let Some(tags) = el.get("tags").and_then(|v| v.as_object()) {
                        if let Some(name) = tags.get("name").and_then(|v| v.as_str()) {
                            let poly = Arc::new(Polygon::new(
                                geo::LineString(way_nodes.iter()
                                                .map(|node| nodes.get(node).expect("node"))
                                                .cloned()
                                                .collect()),
                                vec![]
                            ));
                            locations.push(Location::new(name, poly));
                        }
                    }
                }
                _ => {}
            }
        }
        println!("{} ways", ways.len());

        for el in els {
            let el = el.as_object().expect("el");

            match el.get("type").and_then(|v| v.as_str()) {
                Some("relation") => {
                    if let Some(name) = el.get("tags")
                        .and_then(|v| v.as_object())
                        .and_then(|tags| tags.get("name"))
                        .and_then(|v| v.as_str())
                    {
                        let mut outers = el.get("members").and_then(|v| v.as_array()).expect("members")
                            .iter()
                            .filter_map(|member| {
                                let member = member.as_object().unwrap();
                                let member_type = member.get("type").and_then(|v| v.as_str()).unwrap();
                                let member_role = member.get("role").and_then(|v| v.as_str()).unwrap();
                                if member_type == "way" && member_role == "outer" {
                                    let member_ref = member.get("ref").and_then(|v| v.as_u64()).unwrap();
                                    let way = ways.get(&member_ref).expect("member way");
                                    Some(way.clone())
                                } else {
                                    None
                                }
                            })
                            .collect::<Vec<_>>();
                        let mut rel_nodes = vec![];
                        while outers.len() > 0 {
                            if rel_nodes.len() == 0 {
                                rel_nodes = outers.pop().unwrap();
                            } else if let Some(next) = outers.iter().position(|outer| outer[0] == rel_nodes[rel_nodes.len() - 1]) {
                                rel_nodes.append(&mut outers.remove(next));
                            } else if let Some(next) = outers.iter().position(|outer| outer[outer.len() - 1] == rel_nodes[0]) {
                                let mut new = outers.remove(next);
                                new.append(&mut rel_nodes);
                                rel_nodes = new;
                            } else if let Some(next) = outers.iter().position(|outer| outer[outer.len() - 1] == rel_nodes[rel_nodes.len() - 1]) {
                                let mut new = outers.remove(next);
                                new.reverse();
                                rel_nodes.append(&mut new);
                            } else {
                                println!("inconclusive polygon for relation {}", el.get("id").unwrap().as_u64().unwrap());
                                println!("rel_nodes: {:?}", rel_nodes);
                                println!("remain: {:?}", outers);
                                rel_nodes = vec![];
                                break;
                            }

                            if rel_nodes[0] == rel_nodes[rel_nodes.len() - 1] {
                                let poly = Arc::new(Polygon::new(
                                    geo::LineString(rel_nodes.drain(..)
                                                    .map(|node| nodes.get(&node).expect("node"))
                                                    .cloned()
                                                    .collect()),
                                    vec![]
                                ));
                                locations.push(Location::new(name, poly));
                            }
                        }
                        if rel_nodes.len() > 0 {
                            println!("unclosed polygon for relation {}", el.get("id").unwrap().as_u64().unwrap());
                        }
                    }
                }
                _ => {}
            }
        }
        locations.sort_by(|a, b| a.area.partial_cmp(&b.area).unwrap());
        println!("{} locations", locations.len());

        Locations {
            locations,
        }
    }

    pub fn find(&self, coord: &geo::Coordinate<f64>) -> Option<Arc<String>> {
        for l in &self.locations {
            if l.contains(coord) {
                return Some(l.name.clone());
            }
        }
        None
    }
}