use std::cell::RefCell;
use std::collections::HashMap;

thread_local! {
  pub static FEATURES: RefCell<FeatureFlags> = RefCell::new(FeatureFlags::new());
}

/// accepting feature flags from env var with the format FEATURES=key;type;value,key;type;value
/// with type 'b' for boolean, 's' for string, 'i' for i64, value in the expected type
pub struct FeatureFlags {
  features: HashMap<String, Feature>,
}

impl FeatureFlags {
  pub fn new() -> FeatureFlags {
    let mut features = HashMap::new();
    if let Ok(val) = std::env::var("FEATURES") {
      for feature_val in val.split(",") {
        if let Some((key, f)) = parse_feature(feature_val) {
          info!("adding feature flag ({}, {:?})", key, f);
          features.insert(key, f);
        }
      }
    }

    FeatureFlags { features }
  }

  pub fn get(&self, key: &str) -> Option<&Feature> {
    self.features.get(key)
  }
}

#[derive(Clone, Debug, PartialEq)]
pub enum Feature {
  Boolean(bool),
  String(String),
  Number(i64),
}

impl Feature {
  pub fn is_true(&self) -> bool {
    self == &Feature::Boolean(true)
  }

  pub fn is_string(&self, s: &str) -> bool {
    if let Feature::String(ref s1) = self {
      s1 == s
    } else {
      false
    }
  }
}

fn parse_feature(s: &str) -> Option<(String, Feature)> {
  let v = s.split(";").collect::<Vec<_>>();
  if v.len() != 3 {
    return None;
  }

  let f = if v[1] == "b" {
    if let Some(b) = v[2].parse().ok() {
      Feature::Boolean(b)
    } else {
      return None;
    }
  } else if v[1] == "s" {
    Feature::String(v[2].to_string())
  } else if v[1] == "i" {
    if let Some(i) = v[2].parse().ok() {
      Feature::Number(i)
    } else {
      return None;
    }
  } else {
    return None;
  };

  return Some((v[0].to_string(), f));
}