// Copyright (c) 2017 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

use std::convert::TryFrom;

use minidom::Element;

use error::Error;
use ns;

use data_forms::{DataForm, DataFormType};

#[derive(Debug, Clone, PartialEq)]
pub struct Feature {
    pub var: String,
}

#[derive(Debug, Clone)]
pub struct Identity {
    pub category: String, // TODO: use an enum here.
    pub type_: String, // TODO: use an enum here.
    pub xml_lang: String,
    pub name: Option<String>,
}

#[derive(Debug, Clone)]
pub struct Disco {
    pub node: Option<String>,
    pub identities: Vec<Identity>,
    pub features: Vec<Feature>,
    pub extensions: Vec<DataForm>,
}

impl<'a> TryFrom<&'a Element> for Disco {
    type Error = Error;

    fn try_from(elem: &'a Element) -> Result<Disco, Error> {
        if !elem.is("query", ns::DISCO_INFO) {
            return Err(Error::ParseError("This is not a disco#info element."));
        }

        let mut identities: Vec<Identity> = vec!();
        let mut features: Vec<Feature> = vec!();
        let mut extensions: Vec<DataForm> = vec!();

        let node = elem.attr("node")
                       .and_then(|node| node.parse().ok());

        for child in elem.children() {
            if child.is("feature", ns::DISCO_INFO) {
                let feature = child.attr("var")
                                   .ok_or(Error::ParseError("Feature must have a 'var' attribute."))?;
                features.push(Feature {
                    var: feature.to_owned(),
                });
            } else if child.is("identity", ns::DISCO_INFO) {
                let category = child.attr("category")
                                    .ok_or(Error::ParseError("Identity must have a 'category' attribute."))?;
                if category == "" {
                    return Err(Error::ParseError("Identity must have a non-empty 'category' attribute."))
                }

                let type_ = child.attr("type")
                                 .ok_or(Error::ParseError("Identity must have a 'type' attribute."))?;
                if type_ == "" {
                    return Err(Error::ParseError("Identity must have a non-empty 'type' attribute."))
                }

                let xml_lang = child.attr("xml:lang").unwrap_or("");
                let name = child.attr("name")
                                .and_then(|name| name.parse().ok());
                identities.push(Identity {
                    category: category.to_owned(),
                    type_: type_.to_owned(),
                    xml_lang: xml_lang.to_owned(),
                    name: name,
                });
            } else if child.is("x", ns::DATA_FORMS) {
                let data_form = DataForm::try_from(child)?;
                match data_form.type_ {
                    DataFormType::Result_ => (),
                    _ => return Err(Error::ParseError("Data form must have a 'result' type in disco#info.")),
                }
                match data_form.form_type {
                    Some(_) => extensions.push(data_form),
                    None => return Err(Error::ParseError("Data form found without a FORM_TYPE.")),
                }
            } else {
                return Err(Error::ParseError("Unknown element in disco#info."));
            }
        }

        /*
        // TODO: encode these restrictions only for result disco#info, not get ones.
        if identities.is_empty() {
            return Err(Error::ParseError("There must be at least one identity in disco#info."));
        }
        if features.is_empty() {
            return Err(Error::ParseError("There must be at least one feature in disco#info."));
        }
        if !features.contains(&Feature { var: ns::DISCO_INFO.to_owned() }) {
            return Err(Error::ParseError("disco#info feature not present in disco#info."));
        }
        */

        Ok(Disco {
            node: node,
            identities: identities,
            features: features,
            extensions: extensions
        })
    }
}

impl<'a> Into<Element> for &'a Disco {
    fn into(self) -> Element {
        let mut root = Element::builder("query")
                               .ns(ns::DISCO_INFO)
                               .attr("node", self.node.clone())
                               .build();
        for identity in &self.identities {
            let identity_element = Element::builder("identity")
                                           .ns(ns::DISCO_INFO)
                                           .attr("category", identity.category.clone())
                                           .attr("type", identity.type_.clone())
                                           .attr("xml:lang", identity.xml_lang.clone())
                                           .attr("name", identity.name.clone())
                                           .build();
            root.append_child(identity_element);
        }
        for feature in &self.features {
            let feature_element = Element::builder("feature")
                                          .ns(ns::DISCO_INFO)
                                          .attr("var", feature.var.clone())
                                          .build();
            root.append_child(feature_element);
        }
        for _ in &self.extensions {
            panic!("Not yet implemented!");
        }
        root
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_simple() {
        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity category='client' type='pc'/><feature var='http://jabber.org/protocol/disco#info'/></query>".parse().unwrap();
        let query = Disco::try_from(&elem).unwrap();
        assert!(query.node.is_none());
        assert_eq!(query.identities.len(), 1);
        assert_eq!(query.features.len(), 1);
        assert!(query.extensions.is_empty());
    }

    #[test]
    fn test_invalid() {
        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><coucou/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Unknown element in disco#info.");
    }

    #[test]
    fn test_invalid_identity() {
        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Identity must have a 'category' attribute.");

        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity category=''/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Identity must have a non-empty 'category' attribute.");

        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity category='coucou'/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Identity must have a 'type' attribute.");

        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity category='coucou' type=''/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Identity must have a non-empty 'type' attribute.");
    }

    #[test]
    fn test_invalid_feature() {
        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><feature/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Feature must have a 'var' attribute.");
    }

    #[test]
    #[ignore]
    fn test_invalid_result() {
        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'/>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "There must be at least one identity in disco#info.");

        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity category='client' type='pc'/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "There must be at least one feature in disco#info.");

        let elem: Element = "<query xmlns='http://jabber.org/protocol/disco#info'><identity category='client' type='pc'/><feature var='http://jabber.org/protocol/disco#items'/></query>".parse().unwrap();
        let error = Disco::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "disco#info feature not present in disco#info.");
    }
}