// 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 std::str::FromStr;
use std::collections::BTreeMap;

use minidom::{Element, IntoElements, IntoAttributeValue, ElementEmitter};

use jid::Jid;

use error::Error;

use ns;

use stanza_error::StanzaError;
use delay::Delay;
use ecaps2::ECaps2;

#[derive(Debug, Clone, PartialEq)]
pub enum Show {
    Away,
    Chat,
    Dnd,
    Xa,
}

impl IntoElements for Show {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        let elem = Element::builder(match self {
            Show::Away => "away",
            Show::Chat => "chat",
            Show::Dnd => "dnd",
            Show::Xa => "xa",
        }).build();
        emitter.append_child(elem);
    }
}

pub type Lang = String;
pub type Status = String;

pub type Priority = i8;

/// Lists every known payload of a `<presence/>`.
#[derive(Debug, Clone)]
pub enum PresencePayload {
    StanzaError(StanzaError),
    Delay(Delay),
    ECaps2(ECaps2),

    Unknown(Element),
}

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

    fn try_from(elem: &'a Element) -> Result<PresencePayload, Error> {
        Ok(match (elem.name().as_ref(), elem.ns().unwrap().as_ref()) {
            ("error", ns::JABBER_CLIENT) => PresencePayload::StanzaError(StanzaError::try_from(elem)?),

            // XEP-0203
            ("delay", ns::DELAY) => PresencePayload::Delay(Delay::try_from(elem)?),

            // XEP-0390
            ("c", ns::ECAPS2) => PresencePayload::ECaps2(ECaps2::try_from(elem)?),

            _ => PresencePayload::Unknown(elem.clone()),
        })
    }
}

impl<'a> Into<Element> for &'a PresencePayload {
    fn into(self) -> Element {
        match *self {
            PresencePayload::StanzaError(ref stanza_error) => stanza_error.into(),
            PresencePayload::Delay(ref delay) => delay.into(),
            PresencePayload::ECaps2(ref ecaps2) => ecaps2.into(),

            PresencePayload::Unknown(ref elem) => elem.clone(),
        }
    }
}

#[derive(Debug, Clone, PartialEq)]
pub enum PresenceType {
    /// This value is not an acceptable 'type' attribute, it is only used
    /// internally to signal the absence of 'type'.
    Available,
    Error,
    Probe,
    Subscribe,
    Subscribed,
    Unavailable,
    Unsubscribe,
    Unsubscribed,
}

impl Default for PresenceType {
    fn default() -> PresenceType {
        PresenceType::Available
    }
}

impl FromStr for PresenceType {
    type Err = Error;

    fn from_str(s: &str) -> Result<PresenceType, Error> {
        Ok(match s {
            "error" => PresenceType::Error,
            "probe" => PresenceType::Probe,
            "subscribe" => PresenceType::Subscribe,
            "subscribed" => PresenceType::Subscribed,
            "unavailable" => PresenceType::Unavailable,
            "unsubscribe" => PresenceType::Unsubscribe,
            "unsubscribed" => PresenceType::Unsubscribed,

            _ => return Err(Error::ParseError("Invalid 'type' attribute on presence element.")),
        })
    }
}

impl IntoAttributeValue for PresenceType {
    fn into_attribute_value(self) -> Option<String> {
        Some(match self {
            PresenceType::Available => return None,

            PresenceType::Error => "error",
            PresenceType::Probe => "probe",
            PresenceType::Subscribe => "subscribe",
            PresenceType::Subscribed => "subscribed",
            PresenceType::Unavailable => "unavailable",
            PresenceType::Unsubscribe => "unsubscribe",
            PresenceType::Unsubscribed => "unsubscribed",
        }.to_owned())
    }
}

#[derive(Debug, Clone)]
pub struct Presence {
    pub from: Option<Jid>,
    pub to: Option<Jid>,
    pub id: Option<String>,
    pub type_: PresenceType,
    pub show: Option<Show>,
    pub statuses: BTreeMap<Lang, Status>,
    pub priority: Priority,
    pub payloads: Vec<Element>,
}

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

    fn try_from(root: &'a Element) -> Result<Presence, Error> {
        if !root.is("presence", ns::JABBER_CLIENT) {
            return Err(Error::ParseError("This is not a presence element."));
        }
        let from = root.attr("from")
            .and_then(|value| value.parse().ok());
        let to = root.attr("to")
            .and_then(|value| value.parse().ok());
        let id = root.attr("id")
            .and_then(|value| value.parse().ok());
        let type_ = match root.attr("type") {
            Some(type_) => type_.parse()?,
            None => Default::default(),
        };
        let mut show = None;
        let mut statuses = BTreeMap::new();
        let mut priority = None;
        let mut payloads = vec!();
        for elem in root.children() {
            if elem.is("show", ns::JABBER_CLIENT) {
                if show.is_some() {
                    return Err(Error::ParseError("More than one show element in a presence."));
                }
                for _ in elem.children() {
                    return Err(Error::ParseError("Unknown child in show element."));
                }
                show = Some(match elem.text().as_ref() {
                    "away" => Show::Away,
                    "chat" => Show::Chat,
                    "dnd" => Show::Dnd,
                    "xa" => Show::Xa,

                    _ => return Err(Error::ParseError("Invalid value for show.")),
                });
            } else if elem.is("status", ns::JABBER_CLIENT) {
                for _ in elem.children() {
                    return Err(Error::ParseError("Unknown child in status element."));
                }
                let lang = elem.attr("xml:lang").unwrap_or("").to_owned();
                if statuses.insert(lang, elem.text()).is_some() {
                    return Err(Error::ParseError("Status element present twice for the same xml:lang."));
                }
            } else if elem.is("priority", ns::JABBER_CLIENT) {
                if priority.is_some() {
                    return Err(Error::ParseError("More than one priority element in a presence."));
                }
                for _ in elem.children() {
                    return Err(Error::ParseError("Unknown child in priority element."));
                }
                priority = Some(Priority::from_str(elem.text().as_ref())?);
            } else {
                payloads.push(elem.clone());
            }
        }
        Ok(Presence {
            from: from,
            to: to,
            id: id,
            type_: type_,
            show: show,
            statuses: statuses,
            priority: priority.unwrap_or(0i8),
            payloads: payloads,
        })
    }
}

impl<'a> Into<Element> for &'a Presence {
    fn into(self) -> Element {
        let mut stanza = Element::builder("presence")
                                 .ns(ns::JABBER_CLIENT)
                                 .attr("from", self.from.clone().and_then(|value| Some(String::from(value))))
                                 .attr("to", self.to.clone().and_then(|value| Some(String::from(value))))
                                 .attr("id", self.id.clone())
                                 .attr("type", self.type_.clone())
                                 .append(self.show.clone())
                                 .append(self.statuses.iter().map(|(lang, status)| {
                                      Element::builder("status")
                                              .attr("xml:lang", match lang.as_ref() {
                                                   "" => None,
                                                   lang => Some(lang),
                                               })
                                              .append(status.clone())
                                              .build()
                                  }).collect::<Vec<_>>())
                                 .append(if self.priority == 0 { None } else { Some(format!("{}", self.priority)) })
                                 .build();
        for child in self.payloads.clone() {
            stanza.append_child(child);
        }
        stanza
    }
}

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

    #[test]
    fn test_simple() {
        let elem: Element = "<presence xmlns='jabber:client'/>".parse().unwrap();
        let presence = Presence::try_from(&elem).unwrap();
        assert_eq!(presence.from, None);
        assert_eq!(presence.to, None);
        assert_eq!(presence.id, None);
        assert_eq!(presence.type_, PresenceType::Available);
        assert!(presence.payloads.is_empty());
    }

    #[test]
    fn test_serialise() {
        let elem: Element = "<presence xmlns='jabber:client' type='unavailable'/>".parse().unwrap();
        let presence = Presence {
            from: None,
            to: None,
            id: None,
            type_: PresenceType::Unavailable,
            show: None,
            statuses: BTreeMap::new(),
            priority: 0i8,
            payloads: vec!(),
        };
        let elem2 = (&presence).into();
        assert_eq!(elem, elem2);
    }

    #[test]
    fn test_show() {
        let elem: Element = "<presence xmlns='jabber:client'><show>chat</show></presence>".parse().unwrap();
        let presence = Presence::try_from(&elem).unwrap();
        assert_eq!(presence.payloads.len(), 0);
        assert_eq!(presence.show, Some(Show::Chat));
    }

    #[test]
    fn test_missing_show_value() {
        // "online" used to be a pretty common mistake.
        let elem: Element = "<presence xmlns='jabber:client'><show/></presence>".parse().unwrap();
        let error = Presence::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Invalid value for show.");
    }

    #[test]
    fn test_invalid_show() {
        // "online" used to be a pretty common mistake.
        let elem: Element = "<presence xmlns='jabber:client'><show>online</show></presence>".parse().unwrap();
        let error = Presence::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Invalid value for show.");
    }

    #[test]
    fn test_empty_status() {
        let elem: Element = "<presence xmlns='jabber:client'><status/></presence>".parse().unwrap();
        let presence = Presence::try_from(&elem).unwrap();
        assert_eq!(presence.payloads.len(), 0);
        assert_eq!(presence.statuses.len(), 1);
        assert_eq!(presence.statuses[""], "");
    }

    #[test]
    fn test_status() {
        let elem: Element = "<presence xmlns='jabber:client'><status>Here!</status></presence>".parse().unwrap();
        let presence = Presence::try_from(&elem).unwrap();
        assert_eq!(presence.payloads.len(), 0);
        assert_eq!(presence.statuses.len(), 1);
        assert_eq!(presence.statuses[""], "Here!");
    }

    #[test]
    fn test_multiple_statuses() {
        let elem: Element = "<presence xmlns='jabber:client'><status>Here!</status><status xml:lang='fr'>Là!</status></presence>".parse().unwrap();
        let presence = Presence::try_from(&elem).unwrap();
        assert_eq!(presence.payloads.len(), 0);
        assert_eq!(presence.statuses.len(), 2);
        assert_eq!(presence.statuses[""], "Here!");
        assert_eq!(presence.statuses["fr"], "Là!");
    }

    #[test]
    fn test_invalid_multiple_statuses() {
        let elem: Element = "<presence xmlns='jabber:client'><status xml:lang='fr'>Here!</status><status xml:lang='fr'>Là!</status></presence>".parse().unwrap();
        let error = Presence::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Status element present twice for the same xml:lang.");
    }

    #[test]
    fn test_priority() {
        let elem: Element = "<presence xmlns='jabber:client'><priority>-1</priority></presence>".parse().unwrap();
        let presence = Presence::try_from(&elem).unwrap();
        assert_eq!(presence.payloads.len(), 0);
        assert_eq!(presence.priority, -1i8);
    }

    #[test]
    fn test_invalid_priority() {
        let elem: Element = "<presence xmlns='jabber:client'><priority>128</priority></presence>".parse().unwrap();
        let error = Presence::try_from(&elem).unwrap_err();
        match error {
            Error::ParseIntError(_) => (),
            _ => panic!(),
        };
    }

    #[test]
    fn test_unknown_child() {
        let elem: Element = "<presence xmlns='jabber:client'><test xmlns='invalid'/></presence>".parse().unwrap();
        let presence = Presence::try_from(&elem).unwrap();
        let payload = &presence.payloads[0];
        assert!(payload.is("test", "invalid"));
    }

    #[test]
    #[ignore]
    fn test_invalid_status_child() {
        let elem: Element = "<presence xmlns='jabber:client'><status xmlns='jabber:client'><coucou/></status></presence>".parse().unwrap();
        let error = Presence::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Unknown child in status element.");
    }

    #[test]
    #[ignore]
    fn test_invalid_attribute() {
        let elem: Element = "<status xmlns='jabber:client' coucou=''/>".parse().unwrap();
        let error = Presence::try_from(&elem).unwrap_err();
        let message = match error {
            Error::ParseError(string) => string,
            _ => panic!(),
        };
        assert_eq!(message, "Unknown attribute in status element.");
    }

    #[test]
    fn test_serialise_status() {
        let status = Status::from("Hello world!");
        let mut statuses = BTreeMap::new();
        statuses.insert(String::from(""), status);
        let presence = Presence {
            from: None,
            to: None,
            id: None,
            type_: PresenceType::Unavailable,
            show: None,
            statuses: statuses,
            priority: 0i8,
            payloads: vec!(),
        };
        let elem: Element = (&presence).into();
        assert!(elem.is("presence", ns::JABBER_CLIENT));
        assert!(elem.children().collect::<Vec<_>>()[0].is("status", ns::JABBER_CLIENT));
    }
}