use std::convert::TryInto;
use std::time::Duration;

use http::header::{HeaderValue, IntoHeaderName};
use http::Method;

#[cfg(feature = "charsets")]
use crate::charsets::Charset;
use crate::error::{Error, Result};
use crate::request::proxy::ProxySettings;
use crate::request::{header_append, header_insert, BaseSettings, RequestBuilder};
use crate::tls::Certificate;

/// `Session` is a type that can carry settings over multiple requests. The settings applied to the
/// `Session` are applied to every request created from this `Session`.
#[derive(Debug, Default)]
pub struct Session {
    base_settings: BaseSettings,
}

impl Session {
    /// Create a new `Session` with default settings.
    pub fn new() -> Session {
        Session {
            base_settings: BaseSettings::default(),
        }
    }

    /// Create a new `RequestBuilder` with the GET method and this Session's settings applied on it.
    pub fn get<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::GET, base_url, self.base_settings.clone())
    }

    /// Create a new `RequestBuilder` with the POST method and this Session's settings applied on it.
    pub fn post<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::POST, base_url, self.base_settings.clone())
    }

    /// Create a new `RequestBuilder` with the PUT method and this Session's settings applied on it.
    pub fn put<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::PUT, base_url, self.base_settings.clone())
    }

    /// Create a new `RequestBuilder` with the DELETE method and this Session's settings applied on it.
    pub fn delete<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::DELETE, base_url, self.base_settings.clone())
    }

    /// Create a new `RequestBuilder` with the HEAD method and this Session's settings applied on it.
    pub fn head<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::HEAD, base_url, self.base_settings.clone())
    }

    /// Create a new `RequestBuilder` with the OPTIONS method and this Session's settings applied on it.
    pub fn options<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::OPTIONS, base_url, self.base_settings.clone())
    }

    /// Create a new `RequestBuilder` with the PATCH method and this Session's settings applied on it.
    pub fn patch<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::PATCH, base_url, self.base_settings.clone())
    }

    /// Create a new `RequestBuilder` with the TRACE method and this Session's settings applied on it.
    pub fn trace<U>(&self, base_url: U) -> RequestBuilder
    where
        U: AsRef<str>,
    {
        RequestBuilder::with_settings(Method::TRACE, base_url, self.base_settings.clone())
    }

    //
    // Settings
    //

    /// Modify a header for this `Request`.
    ///
    /// If the header is already present, the value will be replaced. If you wish to append a new header,
    /// use `header_append`.
    ///
    /// # Panics
    /// This method will panic if the value is invalid.
    pub fn header<H, V>(&mut self, header: H, value: V)
    where
        H: IntoHeaderName,
        V: TryInto<HeaderValue>,
        Error: From<V::Error>,
    {
        self.try_header(header, value).expect("invalid header value");
    }

    /// Append a new header for this `Request`.
    ///
    /// The new header is always appended to the request, even if the header already exists.
    ///
    /// # Panics
    /// This method will panic if the value is invalid.
    pub fn header_append<H, V>(&mut self, header: H, value: V)
    where
        H: IntoHeaderName,
        V: TryInto<HeaderValue>,
        Error: From<V::Error>,
    {
        self.try_header_append(header, value).expect("invalid header value");
    }

    /// Modify a header for this `Request`.
    ///
    /// If the header is already present, the value will be replaced. If you wish to append a new header,
    /// use `header_append`.
    pub fn try_header<H, V>(&mut self, header: H, value: V) -> Result<()>
    where
        H: IntoHeaderName,
        V: TryInto<HeaderValue>,
        Error: From<V::Error>,
    {
        header_insert(&mut self.base_settings.headers, header, value)?;
        Ok(())
    }

    /// Append a new header to this `Request`.
    ///
    /// The new header is always appended to the `Request`, even if the header already exists.
    pub fn try_header_append<H, V>(&mut self, header: H, value: V) -> Result<()>
    where
        H: IntoHeaderName,
        V: TryInto<HeaderValue>,
        Error: From<V::Error>,
    {
        header_append(&mut self.base_settings.headers, header, value)?;
        Ok(())
    }

    /// Set the maximum number of headers accepted in responses to this request.
    ///
    /// The default is 100.
    pub fn max_headers(&mut self, max_headers: usize) {
        self.base_settings.max_headers = max_headers;
    }

    /// Set the maximum number of redirections this `Request` can perform.
    ///
    /// The default is 5.
    pub fn max_redirections(&mut self, max_redirections: u32) {
        self.base_settings.max_redirections = max_redirections;
    }

    /// Sets if this `Request` should follow redirects, 3xx codes.
    ///
    /// This value defaults to true.
    pub fn follow_redirects(&mut self, follow_redirects: bool) {
        self.base_settings.follow_redirects = follow_redirects;
    }

    /// Sets a connect timeout for this request.
    ///
    /// The default is 30 seconds.
    pub fn connect_timeout(&mut self, duration: Duration) {
        self.base_settings.connect_timeout = duration;
    }

    /// Sets a read timeout for this request.
    ///
    /// The default is 30 seconds.
    pub fn read_timeout(&mut self, duration: Duration) {
        self.base_settings.read_timeout = duration;
    }

    /// Sets a timeout for the whole request.
    ///
    /// Applies after a TCP connection is established. Defaults to no timeout.
    pub fn timeout(&mut self, duration: Duration) {
        self.base_settings.timeout = Some(duration);
    }

    /// Sets the proxy settigns for this request.
    ///
    /// If left untouched, the defaults are to use system proxy settings found in environment variables.
    pub fn proxy_settings(&mut self, settings: ProxySettings) {
        self.base_settings.proxy_settings = settings;
    }

    /// Set the default charset to use while parsing the response of this `Request`.
    ///
    /// If the response does not say which charset it uses, this charset will be used to decode the request.
    /// This value defaults to `None`, in which case ISO-8859-1 is used.
    #[cfg(feature = "charsets")]
    pub fn default_charset(&mut self, default_charset: Option<Charset>) {
        self.base_settings.default_charset = default_charset;
    }

    /// Sets if this `Request` will announce that it accepts compression.
    ///
    /// This value defaults to true. Note that this only lets the browser know that this `Request` supports
    /// compression, the server might choose not to compress the content.
    #[cfg(feature = "flate2")]
    pub fn allow_compression(&mut self, allow_compression: bool) {
        self.base_settings.allow_compression = allow_compression;
    }

    /// Sets if this `Request` will accept invalid TLS certificates.
    ///
    /// Accepting invalid certificates implies that invalid hostnames are accepted
    /// as well.
    ///
    /// The default value is `false`.
    ///
    /// # Danger
    /// Use this setting with care. This will accept **any** TLS certificate valid or not.
    /// If you are using self signed certificates, it is much safer to add their root CA
    /// to the list of trusted root CAs by your system.
    pub fn danger_accept_invalid_certs(&mut self, accept_invalid_certs: bool) {
        self.base_settings.accept_invalid_certs = accept_invalid_certs;
    }

    /// Sets if this `Request` will accept an invalid hostname in a TLS certificate.
    ///
    /// The default value is `false`.
    ///
    /// # Danger
    /// Use this setting with care. This will accept TLS certificates that do not match
    /// the hostname.
    pub fn danger_accept_invalid_hostnames(&mut self, accept_invalid_hostnames: bool) {
        self.base_settings.accept_invalid_hostnames = accept_invalid_hostnames;
    }

    /// Adds a root certificate that will be trusted.
    pub fn add_root_certificate(&mut self, cert: Certificate) {
        self.base_settings.root_certificates.0.push(cert);
    }
}