use std::collections::HashMap;

pub enum Selector {
    MinZoom(i32),
    MaxZoom(i32),
    HasTag(&'static str),
    TagEquals(&'static str, &'static str),
    And(&'static [Selector]),
    Or(&'static [Selector]),
}

impl Selector {
    fn matches(&self, zoom: &i32, tags: &HashMap<String, String>) -> bool {
        match self {
            Selector::MinZoom(min_zoom) =>
                zoom >= min_zoom,
            Selector::MaxZoom(max_zoom) =>
                zoom <= max_zoom,
            Selector::HasTag(name) =>
                tags.contains_key(*name),
            Selector::TagEquals(name, value) =>
                tags.get(*name).map(|s| s.as_str()) == Some(*value),
            Selector::And(selectors) =>
                selectors.iter().all(|selector| selector.matches(zoom, tags)),
            Selector::Or(selectors) =>
                selectors.iter().any(|selector| selector.matches(zoom, tags)),
        }
    }
}

type Color = (f64, f64, f64, f64);

pub struct Style {
    pub z_index: i32,
    pub stroke: Option<(f64, Color)>,
    pub fill: Option<Color>,
}

impl Style {
    const DEFAULT: Style = Style {
        z_index: 0,
        stroke: None,
        fill: None,
    };
}

const STYLES: &[(Selector, Style)] = &[
    (Selector::HasTag("tunnel"),
     Style { z_index: -10, ..Style::DEFAULT }),

    (Selector::TagEquals("landuse", "forest"),
     Style { z_index: -8, fill: Some((0.2, 0.7, 0.2, 0.8)), ..Style::DEFAULT }),
    (Selector::TagEquals("leisure", "park"),
     Style { z_index: -8, fill: Some((0.3, 0.7, 0.3, 0.8)), ..Style::DEFAULT }),
    (Selector::TagEquals("landuse", "meadow"),
     Style { z_index: -6, fill: Some((0.2, 0.8, 0.2, 0.8)), ..Style::DEFAULT }),
    (Selector::TagEquals("landuse", "grass"),
     Style { z_index: -5, fill: Some((0.3, 0.9, 0.3, 0.8)), ..Style::DEFAULT }),

    (Selector::TagEquals("landuse", "industrial"),
     Style { z_index: -9, fill: Some((0.3, 0.3, 0.2, 0.8)), ..Style::DEFAULT }),
    (Selector::TagEquals("landuse", "construction"),
     Style { z_index: -9, fill: Some((0.5, 0.5, 0.3, 0.8)), ..Style::DEFAULT }),

    (Selector::TagEquals("highway", "motorway"),
     Style { z_index: 10, stroke: Some((50., (1., 1., 1., 1.))), ..Style::DEFAULT }),
    (Selector::TagEquals("highway", "trunk"),
     Style { z_index: 9, stroke: Some((35., (1., 1., 1., 1.))), ..Style::DEFAULT }),
    (Selector::TagEquals("highway", "primary"),
     Style { z_index: 8, stroke: Some((25., (1., 1., 1., 1.))), ..Style::DEFAULT }),
    (Selector::And(&[Selector::TagEquals("highway", "secondary"), Selector::MinZoom(12)]),
     Style { z_index: 7, stroke: Some((20., (1., 1., 1., 1.))), ..Style::DEFAULT }),
    (Selector::And(&[Selector::TagEquals("highway", "tertiary"), Selector::MinZoom(14)]),
     Style { z_index: 6, stroke: Some((15., (1., 1., 1., 1.))), ..Style::DEFAULT }),
    (Selector::And(&[Selector::TagEquals("highway", "residential"), Selector::MinZoom(16)]),
     Style { z_index: 5, stroke: Some((10., (1., 1., 1., 1.))), ..Style::DEFAULT }),
    (Selector::And(&[Selector::TagEquals("highway", "living_street"), Selector::MinZoom(16)]),
     Style { z_index: 4, stroke: Some((8., (1., 1., 1., 1.))), ..Style::DEFAULT }),
    (Selector::And(&[Selector::HasTag("highway"), Selector::MinZoom(18)]),
     Style { z_index: 3, stroke: Some((6., (1., 1., 1., 1.))), ..Style::DEFAULT }),

    (Selector::And(&[Selector::HasTag("railway"), Selector::MinZoom(10)]),
     Style { z_index: 20, stroke: Some((3., (0., 0., 0., 1.))), ..Style::DEFAULT }),

    (Selector::Or(&[Selector::HasTag("waterway"), Selector::TagEquals("natural", "water")]),
     Style { z_index: -2, fill: Some((0.5, 0.5, 0.7, 1.)), ..Style::DEFAULT }),

    (Selector::And(&[Selector::HasTag("building"), Selector::MinZoom(16)]),
     Style { z_index: 30, fill: Some((0.7, 0.7, 0.7, 1.)), stroke: Some((1., (0., 0., 0., 1.))), ..Style::DEFAULT }),
];

pub fn find(zoom: &i32, tags: &HashMap<String, String>) -> Option<&'static Style> {
    for (selector, style) in STYLES {
        if selector.matches(zoom, tags) {
            return Some(&style);
        }
    }

    None
}