use std::ops::{Range, Deref};
use std::fmt;
use lazy_static::lazy_static;
use regex::Regex;
use crate::regex_generator;

#[derive(Clone)]
pub struct Url<S: AsRef<str>> {
    full: S,
    scheme: Option<Range<usize>>,
    user: Option<Range<usize>>,
    password: Option<Range<usize>>,
    host: Option<Range<usize>>,
    port: Option<Range<usize>>,
    path: Option<Range<usize>>,
    query: Option<Range<usize>>,
    fragment: Option<Range<usize>>,
}
#[derive(Debug, PartialEq, Eq)]
pub enum Query<'a> {
    Field(&'a str),
    Form(&'a str, &'a str),
}
impl<S> Url<S> 
    where S: AsRef<str>
{
    /**
    Create a new Url instance.

    Parse the url given in parameter and store it and ranges of several element present in the url into the instance.
    If the url is well formed, it returns theUrl instance in an [`Ok`] value. An empty [`Err`] is returns otherwise (meaning parsing doesn't capture the url well)

    **Note** : To parse the url, it uses a very long regular expression. As it works pretty well, it is planned to be improved.
    */
    pub fn new(v: S) -> Result<Url<S>, &'static str> {
        lazy_static! {
            static ref URL_REGEX: Regex = {
                Regex::new(regex_generator::url_regex())
                    .expect(r"/!\ Regex error from internal string. /!\")
            };
        }
        let test = v.as_ref();
        let captures: regex::Captures = match URL_REGEX.captures(test) {
            Some(captures) => captures,
            None => return Err("Url not valid"),
        };
        let (scheme, user, password, host, port, path, query, fragment) = {
            let to_opt_range = |i| (&captures).get(i).map(|m| m.range());
            (
                to_opt_range(1),
                to_opt_range(2),
                to_opt_range(3),
                to_opt_range(4),
                to_opt_range(5),
                to_opt_range(6),
                to_opt_range(7),
                to_opt_range(8),
            )
        };
        
        Ok(Url {
            full: v,
            scheme, user, password, host, port, path, query, fragment
        })
    }
    /**
    Returns the complete url.
    */
    pub fn full(&self) -> &str {
        self.full.as_ref()
    }
    fn range_to_str(&self, range: &Option<Range<usize>>) -> Option<&str> {
        range.clone().map(|s| &self.full.as_ref()[s])
    }
    /**
    Returns the scheme of the url if present, [`None`] otherwise.

    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.scheme(), Some("https"));
    let url = Url::new("/path/example").unwrap();
    assert_eq!(url.scheme(), None);
    ```
    */
    pub fn scheme(&self) -> Option<&str>
    {
        self.range_to_str(&self.scheme)
    }
    /**
    Returns the username of the url if present, [`None`] otherwise.

    In a URL (to connect ftp for example), you can pass userinfo as `username:password`.

    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.user(), Some("username"));
    let url = Url::new("https://www.example.com").unwrap();
    assert_eq!(url.user(), None);
    ```
    */
    pub fn user(&self) -> Option<&str>
    {
        self.range_to_str(&self.user)
    }
    /**
    Returns the password of the url if present, [`None`] otherwise.

    In a URL (to connect ftp for example), you can pass userinfo as `username:password`.
    Note that the password in the url is deprecated as the data is displayed in clear. 

    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.password(), Some("password"));
    let url = Url::new("https://www.example.com").unwrap();
    assert_eq!(url.password(), None);
    ```
    */
    pub fn password(&self) -> Option<&str>
    {
        self.range_to_str(&self.password)
    }
    /**
    Returns the host of the url if present, [`None`] otherwise.

    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.host(), Some("www.example.com"));
    let url = Url::new("http://localhost:8080").unwrap();
    assert_eq!(url.host(), Some("localhost"));
    let url = Url::new("/path/example").unwrap();
    assert_eq!(url.host(), None);
    ```
    */
    pub fn host(&self) -> Option<&str>
    {
        self.range_to_str(&self.host)
    }
    /**
    Returns the port of the url if present, [`None`] otherwise.
    
    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.port(), Some("8080"));
    let url = Url::new("/path/example").unwrap();
    assert_eq!(url.port(), None);
    ```
    */
    pub fn port(&self) -> Option<&str>
    {
        self.range_to_str(&self.port)
    }
    /**
    Returns the path of the url.

    Even if the path returns an [`Option`], it will never return [`None`], but can return [`Some("")`]
    
    [`Some("")`]: https://doc.rust-lang.org/nightly/core/option/enum.Option.html#variant.Some
    
    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.path(), Some("/path/to/file"));
    let url = Url::new("https://www.example.com").unwrap();
    assert_eq!(url.path(), Some(""));
    ```
    */
    pub fn path(&self) -> Option<&str>
    {
        self.range_to_str(&self.path)
    }
    /**
    Returns the query of the url if present, [`None`] otherwise.

    It returns the full query in a string slice, including the question mark. 
    To format into a [`Vec`], see [`Self::dispatch_query()`].
    
    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.query(), Some("?field=value"));
    let url = Url::new("/path/example").unwrap();
    assert_eq!(url.query(), None);
    ```
    */
    pub fn query(&self) -> Option<&str>
    {
        self.range_to_str(&self.query)
    }
    /**
    Returns the fragment of the url if present, [`None`] otherwise.
    
    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://username:password@www.example.com:8080/path/to/file?field=value#fragment").unwrap();
    assert_eq!(url.frament(), Some("#fragment"));
    let url = Url::new("/path/example").unwrap();
    assert_eq!(url.frament(), None);
    ```
    */
    pub fn fragment(&self) -> Option<&str>
    {
        self.range_to_str(&self.fragment)
    }
    /**
    Split the query into a [`Vec`] of [`Query`].
    
    ## Example
    ```
    use url_compose::Url;
    use url_compose::Query::{Form, Field};

    let url = Url::new("/?field1=value1&field2=value2&present").unwrap();
    assert_eq!(url.dispatch_query(), [Form("field1", "value1"), Form("field2", "value2"), Field("present")]);
    let url = Url::new("/?field1=value1;field2=value2").unwrap();
    assert_eq!(url.dispatch_query(), [Form("field1", "value1"), Form("field2", "value2")]);
    let url = Url::new("/").unwrap();
    assert_eq!(url.dispatch_query(), []);
    ```
    */
    pub fn dispatch_query(&self) -> Vec<Query> {
        let queries = match self.query() {
            Some(v) => v,
            None => return Vec::new()
        };
        let queries = &queries[1..];
        let mut result = vec![];
        for query in queries.split(|c| c=='&' || c==';') {
            result.push(match query.find('=') {
                Some(pos) => Query::Form(&query[0..pos], &query[pos+1..]),
                None => Query::Field(query)
            });
        }
        result
    }
    /**
    Split the host domains into a [`Vec`] of `&str`.

    If the host isn't present in the url, the function returns a empty value.
    
    ## Example
    ```
    use url_compose::Url;

    let url = Url::new("https://www.example.com/").unwrap();
    assert_eq!(url.dispatch_domains(), ["www","example","com"]);
    let url = Url::new("/").unwrap();
    assert_eq!(url.dispatch_domains(), [] as [&str;0]);
    ```
    */
    pub fn dispatch_domains(&self) -> Vec<&str> {
        match self.host() {
            Some(domains) => domains.split('.').collect(),
            None => Vec::new(),
        }
    }
}

impl<S> From<Url<S>> for String 
    where S: AsRef<str>
{
    fn from(v: Url<S>) -> String {
        String::from(v.full.as_ref())
    }
}

impl<S> fmt::Debug for Url<S>
    where S: AsRef<str>
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Url")
         .field("full", &self.full.as_ref())
         .field("scheme", &self.scheme())
         .field("user", &self.user())
         .field("host", &self.host())
         .field("port", &self.port())
         .field("path", &self.path())
         .field("query", &self.query())
         .field("fragment", &self.fragment())
         .finish()
    }
}
impl<S> fmt::Display for Url<S>
    where S: AsRef<str>
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.full.as_ref())
    }
}
impl<S> AsRef<str> for Url<S>
    where S: AsRef<str> 
{
    fn as_ref(&self) -> &str {
        self.full()
    }
}
impl<S> AsRef<[u8]> for Url<S>
    where S: AsRef<str> 
{
    fn as_ref(&self) -> &[u8] {
        self.full().as_ref()
    }
}
impl<S> Deref for Url<S>
    where S: AsRef<str> 
{
    type Target = str;
    fn deref(&self) -> &str {
        self.full()
    }
}