use std;
use std::rc::Rc;
use std::path::PathBuf;
use std::ops::Index;
use std::str::FromStr;
use std::collections::HashMap;

use failure::Fail;
use http::{StatusCode};
use regex::{Regex, RegexSet, Captures};

use body::Body;
use httpresponse::HttpResponse;
use error::{ResponseError, UriSegmentError};

/// A trait to abstract the idea of creating a new instance of a type from a path parameter.
pub trait FromParam: Sized {
    /// The associated error which can be returned from parsing.
    type Err: ResponseError;

    /// Parses a string `s` to return a value of this type.
    fn from_param(s: &str) -> Result<Self, Self::Err>;
}

/// Route match information
///
/// If resource path contains variable patterns, `Params` stores this variables.
#[derive(Debug)]
pub struct Params {
    text: String,
    matches: Vec<Option<(usize, usize)>>,
    names: Rc<HashMap<String, usize>>,
}

impl Params {
    pub(crate) fn new(names: Rc<HashMap<String, usize>>,
                      text: &str,
                      captures: &Captures) -> Self
    {
        Params {
            names,
            text: text.into(),
            matches: captures
                .iter()
                .map(|capture| capture.map(|m| (m.start(), m.end())))
                .collect(),
        }
    }

    pub(crate) fn empty() -> Self
    {
        Params {
            text: String::new(),
            names: Rc::new(HashMap::new()),
            matches: Vec::new(),
        }
    }

    /// Check if there are any matched patterns
    pub fn is_empty(&self) -> bool {
        self.names.is_empty()
    }

    fn by_idx(&self, index: usize) -> Option<&str> {
        self.matches
            .get(index + 1)
            .and_then(|m| m.map(|(start, end)| &self.text[start..end]))
    }

    /// Get matched parameter by name without type conversion
    pub fn get(&self, key: &str) -> Option<&str> {
        self.names.get(key).and_then(|&i| self.by_idx(i - 1))
    }

    /// Get matched `FromParam` compatible parameter by name.
    ///
    /// If keyed parameter is not available empty string is used as default value.
    ///
    /// ```rust
    /// # extern crate actix_web;
    /// # use actix_web::*;
    /// fn index(req: HttpRequest) -> Result<String> {
    ///    let ivalue: isize = req.match_info().query("val")?;
    ///    Ok(format!("isuze value: {:?}", ivalue))
    /// }
    /// # fn main() {}
    /// ```
    pub fn query<T: FromParam>(&self, key: &str) -> Result<T, <T as FromParam>::Err>
    {
        if let Some(s) = self.get(key) {
            T::from_param(s)
        } else {
            T::from_param("")
        }
    }
}

impl<'a> Index<&'a str> for Params {
    type Output = str;

    fn index(&self, name: &'a str) -> &str {
        self.get(name).expect("Value for parameter is not available")
    }
}

/// Creates a `PathBuf` from a path parameter. The returned `PathBuf` is
/// percent-decoded. If a segment is equal to "..", the previous segment (if
/// any) is skipped.
///
/// For security purposes, if a segment meets any of the following conditions,
/// an `Err` is returned indicating the condition met:
///
///   * Decoded segment starts with any of: `.` (except `..`), `*`
///   * Decoded segment ends with any of: `:`, `>`, `<`
///   * Decoded segment contains any of: `/`
///   * On Windows, decoded segment contains any of: '\'
///   * Percent-encoding results in invalid UTF8.
///
/// As a result of these conditions, a `PathBuf` parsed from request path parameter is
/// safe to interpolate within, or use as a suffix of, a path without additional
/// checks.
impl FromParam for PathBuf {
    type Err = UriSegmentError;

    fn from_param(val: &str) -> Result<PathBuf, UriSegmentError> {
        let mut buf = PathBuf::new();
        for segment in val.split('/') {
            if segment == ".." {
                buf.pop();
            } else if segment.starts_with('.') {
                return Err(UriSegmentError::BadStart('.'))
            } else if segment.starts_with('*') {
                return Err(UriSegmentError::BadStart('*'))
            } else if segment.ends_with(':') {
                return Err(UriSegmentError::BadEnd(':'))
            } else if segment.ends_with('>') {
                return Err(UriSegmentError::BadEnd('>'))
            } else if segment.ends_with('<') {
                return Err(UriSegmentError::BadEnd('<'))
            } else if segment.is_empty() {
                continue
            } else if cfg!(windows) && segment.contains('\\') {
                return Err(UriSegmentError::BadChar('\\'))
            } else {
                buf.push(segment)
            }
        }

        Ok(buf)
    }
}

#[derive(Fail, Debug)]
#[fail(display="Error")]
pub struct BadRequest<T>(T);

impl<T> BadRequest<T> {
    pub fn cause(&self) -> &T {
        &self.0
    }
}

impl<T> ResponseError for BadRequest<T>
    where T: Send + Sync + std::fmt::Debug +std::fmt::Display + 'static,
          BadRequest<T>: Fail
{
    fn error_response(&self) -> HttpResponse {
        HttpResponse::new(StatusCode::BAD_REQUEST, Body::Empty)
    }
}

macro_rules! FROM_STR {
    ($type:ty) => {
        impl FromParam for $type {
            type Err = BadRequest<<$type as FromStr>::Err>;

            fn from_param(val: &str) -> Result<Self, Self::Err> {
                <$type as FromStr>::from_str(val).map_err(BadRequest)
            }
        }
    }
}

FROM_STR!(u8);
FROM_STR!(u16);
FROM_STR!(u32);
FROM_STR!(u64);
FROM_STR!(usize);
FROM_STR!(i8);
FROM_STR!(i16);
FROM_STR!(i32);
FROM_STR!(i64);
FROM_STR!(isize);
FROM_STR!(f32);
FROM_STR!(f64);
FROM_STR!(String);
FROM_STR!(std::net::IpAddr);
FROM_STR!(std::net::Ipv4Addr);
FROM_STR!(std::net::Ipv6Addr);
FROM_STR!(std::net::SocketAddr);
FROM_STR!(std::net::SocketAddrV4);
FROM_STR!(std::net::SocketAddrV6);


pub struct RouteRecognizer<T> {
    prefix: usize,
    patterns: RegexSet,
    routes: Vec<(Pattern, T)>,
}

impl<T> Default for RouteRecognizer<T> {

    fn default() -> Self {
        RouteRecognizer {
            prefix: 0,
            patterns: RegexSet::new([""].iter()).unwrap(),
            routes: Vec::new(),
        }
    }
}

impl<T> RouteRecognizer<T> {

    pub fn new<P: Into<String>, U>(prefix: P, routes: U) -> Self
        where U: IntoIterator<Item=(String, T)>
    {
        let mut paths = Vec::new();
        let mut handlers = Vec::new();
        for item in routes {
            let pat = parse(&item.0);
            handlers.push((Pattern::new(&pat), item.1));
            paths.push(pat);
        };
        let regset = RegexSet::new(&paths);

        RouteRecognizer {
            prefix: prefix.into().len() - 1,
            patterns: regset.unwrap(),
            routes: handlers,
        }
    }

    pub fn set_routes(&mut self, routes: Vec<(&str, T)>) {
        let mut paths = Vec::new();
        let mut handlers = Vec::new();
        for item in routes {
            let pat = parse(item.0);
            handlers.push((Pattern::new(&pat), item.1));
            paths.push(pat);
        };
        self.patterns = RegexSet::new(&paths).unwrap();
        self.routes = handlers;
    }

    pub fn set_prefix<P: Into<String>>(&mut self, prefix: P) {
        let p = prefix.into();
        if p.ends_with('/') {
            self.prefix = p.len() - 1;
        } else {
            self.prefix = p.len();
        }
    }

    pub fn recognize(&self, path: &str) -> Option<(Option<Params>, &T)> {
        let p = &path[self.prefix..];
        if p.is_empty() {
            if let Some(idx) = self.patterns.matches("/").into_iter().next() {
                let (ref pattern, ref route) = self.routes[idx];
                return Some((pattern.match_info(&path[self.prefix..]), route))
            }
        } else if let Some(idx) = self.patterns.matches(p).into_iter().next() {
            let (ref pattern, ref route) = self.routes[idx];
            return Some((pattern.match_info(&path[self.prefix..]), route))
        }
        None
    }
}

struct Pattern {
    re: Regex,
    names: Rc<HashMap<String, usize>>,
}

impl Pattern {
    fn new(pattern: &str) -> Self {
        let re = Regex::new(pattern).unwrap();
        let names = re.capture_names()
            .enumerate()
            .filter_map(|(i, name)| name.map(|name| (name.to_owned(), i)))
            .collect();

        Pattern {
            re,
            names: Rc::new(names),
        }
    }

    fn match_info(&self, text: &str) -> Option<Params> {
        let captures = match self.re.captures(text) {
            Some(captures) => captures,
            None => return None,
        };

        Some(Params::new(Rc::clone(&self.names), text, &captures))
    }
}

pub(crate) fn check_pattern(path: &str) {
    if let Err(err) = Regex::new(&parse(path)) {
        panic!("Wrong path pattern: \"{}\" {}", path, err);
    }
}

fn parse(pattern: &str) -> String {
    const DEFAULT_PATTERN: &str = "[^/]+";

    let mut re = String::from("^/");
    let mut in_param = false;
    let mut in_param_pattern = false;
    let mut param_name = String::new();
    let mut param_pattern = String::from(DEFAULT_PATTERN);

    for (index, ch) in pattern.chars().enumerate() {
        // All routes must have a leading slash so its optional to have one
        if index == 0 && ch == '/' {
            continue;
        }

        if in_param {
            // In parameter segment: `{....}`
            if ch == '}' {
                re.push_str(&format!(r"(?P<{}>{})", &param_name, &param_pattern));

                param_name.clear();
                param_pattern = String::from(DEFAULT_PATTERN);

                in_param_pattern = false;
                in_param = false;
            } else if ch == ':' {
                // The parameter name has been determined; custom pattern land
                in_param_pattern = true;
                param_pattern.clear();
            } else if in_param_pattern {
                // Ignore leading whitespace for pattern
                if !(ch == ' ' && param_pattern.is_empty()) {
                    param_pattern.push(ch);
                }
            } else {
                param_name.push(ch);
            }
        } else if ch == '{' {
            in_param = true;
        } else {
            re.push(ch);
        }
    }

    re.push('$');
    re
}

#[cfg(test)]
mod tests {
    use regex::Regex;
    use super::*;
    use std::iter::FromIterator;

    #[test]
    fn test_path_buf() {
        assert_eq!(PathBuf::from_param("/test/.tt"), Err(UriSegmentError::BadStart('.')));
        assert_eq!(PathBuf::from_param("/test/*tt"), Err(UriSegmentError::BadStart('*')));
        assert_eq!(PathBuf::from_param("/test/tt:"), Err(UriSegmentError::BadEnd(':')));
        assert_eq!(PathBuf::from_param("/test/tt<"), Err(UriSegmentError::BadEnd('<')));
        assert_eq!(PathBuf::from_param("/test/tt>"), Err(UriSegmentError::BadEnd('>')));
        assert_eq!(PathBuf::from_param("/seg1/seg2/"),
                   Ok(PathBuf::from_iter(vec!["seg1", "seg2"])));
        assert_eq!(PathBuf::from_param("/seg1/../seg2/"),
                   Ok(PathBuf::from_iter(vec!["seg2"])));
    }

    #[test]
    fn test_recognizer() {
        let mut rec = RouteRecognizer::<usize>::default();

        let routes = vec![
            ("/name", 1),
            ("/name/{val}", 2),
            ("/name/{val}/index.html", 3),
            ("/v{val}/{val2}/index.html", 4),
            ("/v/{tail:.*}", 5),
        ];
        rec.set_routes(routes);

        let (params, val) = rec.recognize("/name").unwrap();
        assert_eq!(*val, 1);
        assert!(params.unwrap().is_empty());

        let (params, val) = rec.recognize("/name/value").unwrap();
        assert_eq!(*val, 2);
        assert!(!params.as_ref().unwrap().is_empty());
        assert_eq!(params.as_ref().unwrap().get("val").unwrap(), "value");
        assert_eq!(&params.as_ref().unwrap()["val"], "value");

        let (params, val) = rec.recognize("/name/value2/index.html").unwrap();
        assert_eq!(*val, 3);
        assert!(!params.as_ref().unwrap().is_empty());
        assert_eq!(params.as_ref().unwrap().get("val").unwrap(), "value2");
        assert_eq!(params.as_ref().unwrap().by_idx(0).unwrap(), "value2");

        let (params, val) = rec.recognize("/vtest/ttt/index.html").unwrap();
        assert_eq!(*val, 4);
        assert!(!params.as_ref().unwrap().is_empty());
        assert_eq!(params.as_ref().unwrap().get("val").unwrap(), "test");
        assert_eq!(params.as_ref().unwrap().get("val2").unwrap(), "ttt");
        assert_eq!(params.as_ref().unwrap().by_idx(0).unwrap(), "test");
        assert_eq!(params.as_ref().unwrap().by_idx(1).unwrap(), "ttt");

        let (params, val) = rec.recognize("/v/blah-blah/index.html").unwrap();
        assert_eq!(*val, 5);
        assert!(!params.as_ref().unwrap().is_empty());
        assert_eq!(params.as_ref().unwrap().get("tail").unwrap(), "blah-blah/index.html");
    }

    fn assert_parse(pattern: &str, expected_re: &str) -> Regex {
        let re_str = parse(pattern);
        assert_eq!(&*re_str, expected_re);
        Regex::new(&re_str).unwrap()
    }

    #[test]
    fn test_parse_static() {
        let re = assert_parse("/", r"^/$");
        assert!(re.is_match("/"));
        assert!(!re.is_match("/a"));

        let re = assert_parse("/name", r"^/name$");
        assert!(re.is_match("/name"));
        assert!(!re.is_match("/name1"));
        assert!(!re.is_match("/name/"));
        assert!(!re.is_match("/name~"));

        let re = assert_parse("/name/", r"^/name/$");
        assert!(re.is_match("/name/"));
        assert!(!re.is_match("/name"));
        assert!(!re.is_match("/name/gs"));

        let re = assert_parse("/user/profile", r"^/user/profile$");
        assert!(re.is_match("/user/profile"));
        assert!(!re.is_match("/user/profile/profile"));
    }

    #[test]
    fn test_parse_param() {
        let re = assert_parse("/user/{id}", r"^/user/(?P<id>[^/]+)$");
        assert!(re.is_match("/user/profile"));
        assert!(re.is_match("/user/2345"));
        assert!(!re.is_match("/user/2345/"));
        assert!(!re.is_match("/user/2345/sdg"));

        let captures = re.captures("/user/profile").unwrap();
        assert_eq!(captures.get(1).unwrap().as_str(), "profile");
        assert_eq!(captures.name("id").unwrap().as_str(), "profile");

        let captures = re.captures("/user/1245125").unwrap();
        assert_eq!(captures.get(1).unwrap().as_str(), "1245125");
        assert_eq!(captures.name("id").unwrap().as_str(), "1245125");

        let re = assert_parse(
            "/v{version}/resource/{id}",
            r"^/v(?P<version>[^/]+)/resource/(?P<id>[^/]+)$",
        );
        assert!(re.is_match("/v1/resource/320120"));
        assert!(!re.is_match("/v/resource/1"));
        assert!(!re.is_match("/resource"));

        let captures = re.captures("/v151/resource/adahg32").unwrap();
        assert_eq!(captures.get(1).unwrap().as_str(), "151");
        assert_eq!(captures.name("version").unwrap().as_str(), "151");
        assert_eq!(captures.name("id").unwrap().as_str(), "adahg32");
    }
}